The Potential Use of Intraoperative Ultrasound to Locate the Axillary Nerve

Home , Deltopectoral groove, Lateral pectoral nerve

Along Its Course Around the Humerus

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the

Graduate School of The Ohio State University

Eric S. Lenko, BS, MPT, OCS

Graduate Program in Anatomy

The Ohio State University

2018

Dissertation Committee:

Professor John Bolte IV, PhD, Advisor

Professor Laura Boucher, PhD, AT, ATC

Professor Yun Seok Kang, PhD

James Latshaw, MD

Eric S. Lenko, MPT, OCS

2018

Abstract

Proximal humerus fractures account for nearly nine percent of all upper extremity fractures. Many of these fractures can be managed conservatively. However, surgical reduction of greater than one centimeter-displaced fractures requires surgical exposure that risks damage to the axillary nerve. There is significant variability in the location of the axillary nerve as it travels around the surgical neck of the humerus, based on how the measurements are taken.

Given the variability in the vertical position of the axillary nerve in the literature, the surgeon is not able to assume the axillary nerve lies within the safe zone, since a percentage of all measured are located closer than five centimeters from the chosen bony landmarks on the scapula. Therefore, the axillary nerve must be specifically identified in each patient in order to avoid iatrogenic injury. Ultrasound imaging may be beneficial in identifying the axillary nerve location intraoperatively to guide the surgeon, since its utility has been previously supported when tracking needle location for axillary nerve blocks. The goal of the study was to compare the location of the axillary nerve along its course around the humerus via dissection and ultrasound imaging. Additionally, this study aimed to determine a prevalence of lateral pectoral nerve branching to the anterior deltoid. The initial study compared the location of the axillary nerve along its course around the surgical neck of the humerus at three divisions, anterior, lateral, and posterior via cadaver dissection. There was no significant difference between the six positions measured. There were three measurements locating the axillary nerve less than five centimeters from the origin of the deltoid. The axillary nerve terminates less than two centimeters from the medial border of the anterior deltoid making it vulnerable to injury during anterior approaches to the shoulder. Ultrasound and dissection was performed on seven

ii shoulders of fresh cadavers to correlate the location of the axillary nerve with respect to the bony landmarks. There was a strong correlation (.831) between the measurements suggesting ultrasound may provide accuracy of the real-time location of the axillary nerve for potential use in the operative environment. The third portion of the study repeated the same six test positions utilizing ultrasound imaging on human volunteers. There was a significant different between the posterior and both the anterior and lateral positions with respect to the deltoid origin on the clavicle and scapula. Again, seven measurements located the axillary nerve proximal to the established safe zone. Finally, the lateral pectoral nerve was found branching to the undersurface of the deltoid after traveling across the deltopectoral groove in four percent of the cadaver samples. Future studies are necessary to derive a comparable percentage from a larger sample size. The four portions of the study contribute to the understanding of locating the axillary nerve within the deltoid. The next step would be to incorporate ultrasound imaging while performing these surgeries on cadavers to determine vulnerability of the axillary nerve and the potential effects on surgical time.

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Dedication

I dedicate the completion of this dissertation to my late mother, Darlene Lenko, who I love and

miss dearly. I want to also dedicate this manuscript to my wife and daughters who mean the

world to me.

Acknowledgements

I would like to first acknowledge a group of individuals who were willing to bend the mold and interview an individual wanting more from the University than he could provide to the

University. My interview committee, Robert DePhilip, PhD, George Martin, PhD, Kenneth Jones,

PhD, and Doug Gould, PhD allowed me to participate in this rigorous graduate degree path as a part-time student while I continued my commitment to my patients.

Dr. Ken Jones took me under his wing early on in this adventure. I expect that his guidance to the committee ensured my acceptance. His passion for teaching made the difficult subjects seem easier to grasp. He was so good at finding structures, when we, newbies, were lost up to our elbows, that a nerve or blood vessel would seemingly “appear” right before our eyes.

Although my path did not often intersect with Dr. Martin, I do recall the panic within me as he approached our table during gross. His questions were challenging, thought provoking, and demanded the deepest understanding of interactions of anatomy and function.

Dr. Bob DePhilip was one of the stalwarts of the program during my long, part-time journey. There were many changes to the department, regarding personnel, direction, and expectation. Dr. DePhilip was always there. He was very approachable and displayed a passion for the uniqueness of the human body. I appreciate the guidance and assistance throughout the process. I credit him for the lateral pectoral nerve portion of this study.

Mark Whitmer and Michelle Whitmer are two individuals that often miss out on the acknowledgments. They, too, have remained dedicated to the school throughout my time at

Ohio State. Without their flexibility and understanding, I would still be looking and begging for cadavers to dissect for the various parts of my studies.

David Bahner, MD and the Ultrasound Special Interest Group lead by Samantha King and

Antoinette Pusateri met the challenge of supplying me with ultrasound equipment for tracking the axillary nerve. They gained much of nothing to assist me as I added additional stress to their already busy lives completing their own degrees and running a very successful Ultrafest 2017.

Tim Best, PhD has been a motivator, guidance counselor, and positive example for completing my degree. I value him as a friend and mentor.

Matt Warren, sales representative for SonoSite, provided access to ultrasound units throughout this process and was very flexible with his time and donation. I appreciate the friendship and hope to see him on the golf course frequently.

My employer, Orthopedic One (formerly Ohio Orthopedic Center of Excellence), has been very flexible with my time and has rarely asked questions about this pursuit. I could not have completed this phase of my life without the support, particularly from Geoff Omiatek.

Dr. John Bolte, IV was lucky enough to take me on as his pupil for most of the research phase of this degree as an advisor. We had many of discussions regarding the progress of my work, the changes in the University, and The Ohio State Buckeyes.

Finally, I would like to thank my Dissertation Committee, Professor John Bolte IV, PhD,

Professor Laura Boucher, PhD, and Professor Yun Seok Kang, PhD for the time and energy to keep me on my toes while writing this manuscript. Though not all of you were part of my candidacy committee, I do appreciate your willingness to guide me through the completion of this degree process. James Latshaw, MD has been a great asset to me as a clinician and his addition to the committee has helped guide our understanding of the surgical difficulties.

Vita

June 1997……………………………………………………………………. Indian Lake High School, Lewistown, OH

June 2…………………….………….………….……. Bachelor of Science, Exercise Physiology, Ohio University

June 2003……………………………………………….………………. Master of Physical Therapy, Ohio University

2002-2003……………………..……………….. Graduate Teaching Assistant, College of Health and Human

Services, Ohio University

June 2003…………………………... Pennation Angle and Fascicle Length of the Tibialis Anterior, Poster

Presentation, American College of Sports Medicine, Annual

Conference, San Francisco, CA

January – June 2010……………..…… Adjunct Faculty, Anatomy, Columbus State Community College

June 2003-July 2007……………….… Physical Therapist, Clinical Instructor, Physiotherapy Associates

August 2007-Present…………………… PhD Student, Division of Anatomy, The Ohio State University

July 2007-Present……………………….… Assistant Director of Physical Therapy and Sports Medicine,

Physical Therapist, Clinical Instructor, Mentor, Orthopedic One

Field of Study

Major Field: Anatomy

vii

Table of Contents

Abstract…………………………………………………………………………………………………………………………..………….ii

Dedication…………………………………………………………………………………………………………………………….……iv

Acknowledgements……………………………………………………………………………………….……………………………v

Vita……………………………………………………………………………………………………………………………..……..……..vii

Table of Contents………………………………………………………………………………………………………………….....viii

List of Tables………………………………………………………………………………………………………………..……….….xiii

List of Figures……………………………………………………………………………………………….…………………………..xiv

Chapter 1: Introduction and Significance……………………………………………………………………………………1

1.1: Anatomical Variations………………………………………………………………………………………………………….2

1.1.1: Axillary Nerve…………………………………………………………………………………………………….…3

1.1.2: Lateral Pectoral Nerve…………………………………………………………………………………..……..4

1.2: Ultrasound Imaging………………………………………………………………………………………………………………5

1.2.1: Significance of Ultrasound Imaging……………………………………………………………………….5

1.2.2: Basics of the Ultrasound Image…………………………………………………………………………….7

1.2.3: Ultrasound Characteristics of Vessels, Nerve, Muscle, and Bone………………………….9

1.3: Research Design…………………………………………………………………………………………………………..…….11

1.3.1: Chapter 3 Research Question and Specific Aims………………………………………………...12

1.3.2: Chapter 4 Research Question and Specific Aims…………………………………………………13

1.3.3: Chapter 5 Research Question and Specific Aims………………………………………………...14

1.3.4: Chapter 6 Research Question and Specific Aims…………………………………………………15

1.4: Significance and Future Directions………………………………………………………………………………….….15

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1.5: Conclusion………………………………………………………………………………………………………………………….16

Chapter 2: Shoulder and Upper Extremity: Anatomy, Injury, and Reconstruction……………………..17

2.1: Embryologic Development…………………………………………………………………………………………………17

2.2: Anatomy of the Shoulder Girdle…………………………………………………………………………………….…..18

2.2.1: Surface Anatomy…………………………………………………………………………………………….….19

2.2.2: Musculoskeletal Anatomy……………………………………………………………………………….….21

2.2.3: Joint Anatomy…………………………………………………………………………………………………….25

2.2.4: Neuroanatomy of the Brachial Plexus…………………………………………………………………27

2.2.5: Functional Anatomy…………………………………………………………………………………………...31

2.3: Common Injuries of the Shoulder Girdle………………………………………………………………………..…..32

2.3.1: Dislocations/Subluxations………………………………………………………………………………..…33

2.3.2: Neer Classification of Proximal Humerus Fractures…………………………………………….34

2.3.3: Muscle/Tendon Injuries………………………………………………………………………………………36

2.4: Operative Management of the Axillary Nerve in Shoulder Injuries……………………………………..37

2.4.1: Proximal Humerus Fractures……………………………………………………………………………...37

2.4.2: Bi-cortical Biceps Tenodesis………………………………………………………………………………..39

2.4.3: Superior approach to Total Shoulder Arthroplasty………………………………………….….40

Chapter 3: A cadaver dissection comparing the vertical position of the axillary nerve along its course………………………………………………………………………………………………..…41

3.1: Abstract………………………………………………………………………………………………………………………..……41

3.2: Introduction…………………………………………………………………………………………………………………….…41

3.2.1: Hypothesis…………………………………………………………………………………………………….……43

3.3: Materials and Methods……………………………………………………………………………………………………...44

3.4: Data Analysis……………………………………………………………………………………………………………………..49

3.5: Results…………………………………………………………………………………………………………………………….…49

3.6: Discussion…………………………………………………………………………………………………………………….……52

3.7: Limitations………………………………………………………………………………………………………………………...54

3.8: Hypothesis and Key Findings………………………………………………………………………………………………54

3.8.1: Hypothesis………………………………………………………………………………………………………….54

3.8.2: Key Findings……………………………………………………………………………………………………….57

Chapter 4: Comparing the Ultrasound location of the Axillary Nerve to Cadaver

Dissection: A Feasibility Study…………………………………………………………………………………………….…….58

4.1: Abstract……………………………………………………………………………………………………………………………..58

4.2: Introduction……………………………………………………………………………………………………………….………59

4.2.1: Hypotheses…………………………………………………………………………………………………………62

4.3: Materials and Methods………………………………………………………………………………………………………62

4.3.1: US Data Collection………………………………………………………………………………………………62

4.3.2: Dissection and Data Collection…………………………………………………………………………...65

4.4: Data Analysis………………………………………………………………………………………………………………………66

4.5: Results ..…………………………………………………………………………………………………………………………….66

4.6: Discussion………………………………………………………………………………………………………………………….69

4.7: Limitations…………………………………………………………………………………………………………………………70

4.8: Summary and Key Findings………………………………………………………………………………………………..70

4.8.1: Hypotheses……………………………………………………………………………………………..………..70

4.8.2: Key Findings………………………………………………………………………………………….…………..71

Chapter 5: Location of the Axillary Nerve along its course via Ultrasound Imaging……………………72

5.1: Abstract……………………………………………………………………………………………………………………………..72

5.2: Introduction……………………………………………………………………………………………………………………….73

5.2.1 Hypothesis…………………………………………………………………………………………………………..75

5.3: Methods…………………………………………………………………………………………………………………………….76

5.4: Data Analysis……………………………………………………………………………………………………………………..80

5.5: Results……………………………………….………………………………………………………………………………………80

5.6: Discussion………………………………………………………………………………………………………………………….82

5.7: Limitations…………………………………………………………………………………………………………………………83

5.8: Hypothesis and Key Findings………………………………………………………………………………………………84

5.8.1: Hypothesis………………………………………………………………………………………………………….84

5.8.2: Key Findings……………………………………………………………………………………………………….86

Chapter 6: Accessory Innervation to the Anterior Deltoid from the Lateral Pectoral Nerve…..…87

6.1: Abstract……………………………………………………………………………………………………….…………………….87

6.2: Introduction………………………………………………………………………………………………………..……………..88

6.2.1: Hypothesis…………………………………………………………………………………………………….……89

6.3: Materials and Methods………………………………………………………………………………………………………89

6.4: Results……………………………………………………………………………………………………………………………….90

6.5: Discussion……………………………………………………………………………………………………………………..…..91

6.6: Limitations and Conclusion………………………………………………………………………………………………..92

Chapter 7: Conclusion and Future Direction……………………………………………………………..…………..….93

Bibliography………………………………………………………………………………………………………………….…..……..95

Appendix A: Consent Forms………………………………………………………………………………………………..…101

Appendix B: Participant Recruitment Materials……………………………………………………………………..106

Appendix C: SPSS Output for Chapter 3 Cadaver Dissection……………………………………………………109

Appendix D: SPSS Output for Chapter 4 Correlation……………………………….………………………………119

Appendix E: SPSS Output for Chapter 5 Ultrasound…………………………………………….………………….122

Appendix F: Ultrasound Images and Pictures for Correlation Study…………………..……………………132

Appendix G: Ultrasound Images for Location of Axillary Nerve………………………………………………141

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List of Tables

Table 1: Muscles of the shoulder complex including innervation, attachments, and primary action………………………………………………………………………………………………………………………………….…….24

Table 2: Raw data for cadaver measurements…………………………………………………………………………..51

Table 3: Descriptive statistics for Chapter 3………………………………………………………………………………51

Table 4: Between Subjects Variable Results………………………………………………………………………..…….52

Table 5: Within Subjects Results……………………………………………………………………………………………….52

Table 6: Hypothesis Outcome for Laterality……………………………………………………………………………...55

Table 7: Hypothesis Outcomes for Location……………………………………………………………………………...56

Table 8: Hypothesis Outcome Proximity to Anterior Border of the Deltoid……………………………....57

Table 9: Raw data for ultrasound and cadaver dissection………………………………………………………….68

Table 10: Descriptive Statistics for axillary nerve position……………………………………………………..….68

Table 11: Correlation between dissection and ultrasound measurements of the axillary nerve position…………………………………………………………………………………………………………………………………….68

Table 12: Hypothesis Results……………………………………………………………………………………………….…...71

Table 13: Raw Data for ultrasound……………………………………………………………………………………………80

Table 14: Descriptive statistics for Chapter 5……………………………………………..……………………..………80

Table 15: Hypothesis testing for laterality…………………………………………………………………………………84

Table 16: Hypothesis testing for location and laterality……………………………………………………….……85

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List of Figures

Figure 1: Branching of the Lateral Pectoral Nerve………………………………………………………………..……..5

Figure 2: Ultrasound-Guided Axillary Nerve Block…………………………………………………………..…………..6

Figure 3: Basics of Ultrasound Imaging………………………………………………………………………..……………..8

Figure 4: Fetal Ultrasound Imaging………………………………………………………………………………………….….9

Figure 5: Characteristics of Vessels and Nerves………………………………………………..……………………….10

Figure 6: Kibler Scapular Dyskinesia………………………………………………………………………..………………..20

Figure 7: Posterior View…………………………………………………………………………………………………..……….20

Figure 8: Anterior View……………………………………………………………………………………………………………..21

Figure 9: Proximal Humerus with long head of biceps (LHB)………………………………………………..……22

Figure 10: Anterior View of the Scapula……………………………………………………………………………….…..22

Figure 11: Posterior View of the Scapula………….……………………………………………………………………….24

Figure 12: Anterior View of the Acromioclavicular Joint…………………………………………………..……….26

Figure 13: Quadrangular Space………………………………………………………………………………….………..……30

Figure 14: Neer Classification of Proximal Humerus Fractures…………………………………………….…….36

Figure 15: Removal of skin overlying the clavicular head of the pectoralis major (black triangle) and anterior deltoid (green triangle) in a left shoulder………………………………………………………….….45

Figure 16: Left posterior shoulder (skin reflected inferiorly)……………………………………………………..46

Figure 17: Posterior Left Shoulder: Posterior deltoid removed from origin and reflected laterally………………………………………………………………………………………………………………………48

Figure 18: Branching Pattern of the Axillary Nerve (deltoid reflected)………..…………………………….48

Figure 19: Measurement of Vertical Position of Axillary nerve……………………….…………………………59

Figure 20: Comparison of the Anterior, Lateral, and Posterior Axillary Nerve Position……………..50

Figure 21: Ultrasound imaging of the axillary nerve……………………………………………………………….…63 Figure 22: Ultrasound measurement of the axillary nerve……………………..…………………………………64

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Figure 23: Neurovascular bundle containing the axillary nerve and the circumflex humeral vessels………………………………………………………………………………………………………………………..65 Figure 24: Measurement of the axillary nerve position……….…………………………………………………….66

Figure 25: Comparison of Ultrasound and Dissection Measurements…………………………………….…67

Figure 26: X-ray of the left shoulder surgical neck……………………………………………………………………74

Figure 27: Plate and screws of right proximal humerus fracture ………………….…………………………..74

Figure 28: Identifying the origin of the deltoid…………………………………………………………………..……..77

Figure 29: Superior View of Left Shoulder Deltoid Origin………………………………………………….……….78

Figure 30: Ultrasound image of the axillary nerve……………………………………………………………………..79

Figure 31: Anterior view of the right shoulder with skin reflected……………………………………….……90

Figure 32: Anterior view of the left shoulder...... 90

Figure 33: Anterior view of the left shoulder……………………………………………………………………..……..91

Chapter 1: Introduction and Significance

Fractures of the proximal humerus are highly prevalent in the aging population most often because of high velocity impact on outstretched arms typically referred to as FOOSH injuries (Fall on Outstretched Hand) resulting in the number one cause of proximal humerus fractures (PHF) ahead of motor vehicle crashes (Roux et al., 2012; Rothe et al., 2012). Karl et al. estimated over two million upper extremity fractures occur annually (67.6 per 10000 persons)

(Karl et al., 2015). At nearly nine percent of all upper extremity fractures (6.0 per 10000 persons), PHF in the United States account for the third highest fracture rate of the upper extremity behind only distal radius/ulna fractures and hand fractures (Karl et al., 2015). Of the total PHF, an estimated 55 and 82 percent occur because of falls in men and women, respectively (Roux et al., 2012). The risk of falling has been correlated with increasing age, increase in daily medications known as polypharmacy, and balance disorders (Ambrose, 2013).

Although not all falls result in injury, osteoporosis is a significant co-morbidity that predisposes one to fracture and it is estimated that nearly 55 percent of men and women over the age of 50 have low bone density or osteoporosis (Roux et al., 2012). Of particular interest to the proximal humerus, there appears to be variable bone quality that may direct fracture patterns towards the greater tuberosity, especially as one ages (Kirchhoff et al., 2010).

The goal of surgical management is to closely restore anatomic alignment and improve the possibility of healing. As with any surgical intervention, the surgeon needs to be aware of anatomical variations. These variations in vascular and neural supply exist throughout the body

(Bergmann et al., 2016). Some anatomical variations are accepted norms while others may be more of an anomaly than a definable variation. When such anomalies are present, it becomes important to further investigate the frequency of occurrence to identify potential vulnerabilities

1 that may exist. It is quite valuable to understand the variability in the course of these structures when surgical interventions are required to restore function in order to avoid intraoperative transection. Damage to neurovascular bundles through surgical technique or acute injury may lead to additional surgical interventions or result in short- and long-term functional deficits.

These neurovascular injuries may ultimately limit recovery (Galvin, Eichinger, 2016; Silliman,

Dean, 1993).

1.1: Anatomical Variations

The paths of larger nerves are rather consistent, but origin and termination may be variable. The pectoral nerves and the axillary nerve (AN) have various origins from the brachial plexus but their main trunks travel in predictable directions within the thorax and shoulder, respectively. The path of the AN makes it vulnerable to injury from fractures of the proximal humerus, open reconstruction of the shoulder through various surgical procedures including deltoid splitting or deltopectoral groove approaches, and dislocation of the glenohumeral joint

(Silliman, Dean, 1993; Junior et al., 2011; Traver et al., 2016; Westphal et al., 2017; Galvin,

Eichinger, 2016). There has been important research to determine the branching of the main trunks into anterior and posterior divisions as it relates to the quadrangular space (Kontakis et al., 1999; Loukas et al., 2009; Stecco et al., 2010; Tenor et al., 2011; Gurushantappa, Kuppasad,

2015). However, the proximity of termination of the anterior division of the AN and its vertical position within the anterior deltoid as it relates to anterior approaches to the shoulder has been quite variable in the literature (Jerome, Rahmohan, 2012; Chen et al., 2012). In fact, there may even be a difference between patient populations in regard to ethnicity, sex, height and weight

(Chen et al., 2012; Lui et al., 2011). An understanding of the typical end-point medially and 2 superiorly of the anterior division of the AN compared to the location at the quadrangular space may formally determine its at-risk location during common surgical approaches to the shoulder.

A comprehensive review of the location of the AN through cadaver dissection will further the awareness of the predictable position as it relates to proximal humerus fractures.

The primary function of the lateral pectoral nerve (LPN) is to innervate the clavicular and a portion of the sternal heads of the pectoralis major (Beheiry, 2012). However, supplemental or secondary functions of peripheral nerves exist as new research builds our understanding of anatomy and function. Supplemental innervation of the anterior deltoid by the lateral pectoral nerve has been described previously in the literature through case studies but no definitive frequency has been established (Hovelacque, 1927; Porzionato et al., 2012; Solomon et al.,

1997; http://anatomyatlases.org accessed 10/2015). The briefly described course of this supplemental innervation makes it vulnerable to injury during open deltopectoral and other anterior approaches to shoulder reconstruction. A thorough investigation of the presence of this accessory innervation is necessary, first, to determine the overall frequency of occurrence and, second, to ultimately establish the functional deficits that occur from its disruption or damage.

1.1.1: Axillary Nerve

The vertical position of the AN has been variable in the literature and full agreement on the “safe zone” within the deltoid has not been met (Cetik et al., 2006; Kontakis et al., 1999;

Loukas et al., 2009; Stecco et al., 2010; Uz et al., 2007; Jerome, Rajmohan, 2012; Chen et al.,

2012). Traditionally, 5cm inferior from the lateral border of the acromion has provided safety to the AN. However, recent studies have challenged this thought as a wide range of

3 measurements have been recommended to provide a “safe zone” for the AN (Westphal et al.,

2017; Traver et al., 2016). However, most do not specifically differentiate the posterior, middle, and anterior thirds of the nerve. Additional cadaver dissections will help to build a stronger case for the true safe zone to protect from iatrogenic injury. The anterior portion itself, however, requires more specific investigation as it lies in a more critical area for surgical approaches to the shoulder and appears to travel more proximally than the location exiting the quadrangular space.

1.1.2: Lateral Pectoral Nerve

The primary function of the LPN is to provide innervation to the pectoralis muscle group.

However, the LPN has been described in case studies to provide innervation of the anterior deltoid

(Solomon et al., 1997). As this nerve may travel through the deltopectoral groove laterally, it may be vulnerable to transection during the deltopectoral approaches. Figure 1 shows an example of a branch from the LPN traveling through the deltopectoral groove to the undersurface of the deltoid.

Figure 1: Branching of the Lateral Pectoral Nerve. The yellow arrow indicates a branch of the LPN. The red and blue arrows indicate a branch of the thoracoacromial artery and vein, respectively.

1.2: Ultrasound Imaging

1.2.1: Significance of Ultrasound Imaging

Real-time ultrasound (US) imaging has been used to assist in placement of nerve blocks of the brachial plexus and has recently been described for more peripheral applications (Rothe et al., 2011; Schafhalter-Zoppoth, Gray, 2005). For instance, US can be utilized to evaluate not only the location of peripheral nerves but also grade damage and healing of these nerves

(Lawande et al., 2014; Kowalska, Sudot-Szopiska, 2012; Padua et al., 2012). The structures are identified with diagnostic, portable US units and have been shown to be superior to fluoroscopic guidance and EMG-response nerve blocks (Clendenen et al., 2013; Lewis et al., 2015). During the procedure, the tip of the needle is visualized for proximity to the target and the injected material is seen bathing the nerve for a successful block (Figure 2). 5

Figure 2: Ultrasound-Guided Axillary Nerve Block. White Arrows indicate the needle. A is the Axillary Nerve. TM is the Teres Minor (Rothe et al., 2011).

The benefits of US continue to grow with our understanding of the usefulness in screening procedures. It would be beneficial to utilize this technology pre-operatively to identify the location of vulnerable structures to avoid intra-operative damage. For instance, US may be useful in identifying the path of the AN prior to open, anterior reconstructions of the shoulder and may dictate the choice of approach. A portion of operative time is devoted to locating and avoiding the AN, extending the length of the procedure and the need for anesthesia. If US can be used preoperatively or intraoperatively to identify its location, then surgical times may be improved, and injury rates may be lessened. Therefore, US may be used to locate vulnerable structures prior to skin incisions to direct the surgeon’s decision making and may offer real-time location while making incisions or inserting cortical screws.

1.2.2: Basics of the Ultrasound Image

The basics of the ultrasound image are diagrammed in Figure 3. The depth of the US image contains the near field (most superficial) and far fields (deepest). The leading edge of the transducer is identified by a line or dot on the casing and is typically oriented proximally or anteriorly on extremity images. Each image has hyper- and hypoechoic structures based on the amount of sound energy that is reflected back to the transducer. For instance, the density of the cortex of bone will reflect a majority of the sound waves back to the transducer. This will appear very white, or hyperechoic. Striated muscle is easily noticeable on the ultrasound image as sound was are reflected by the connective tissue that surrounds muscle fascicles. Sound travels rather easily through fat and water so very little of the sound waves are absorbed or reflected back to the transducer. This area will appear very dark, even black, making them hypoechoic. Soundwaves travel back to the transducer best when they are perpendicular to the soundhead. If there is an angle to the penetration of sound waves, the structure will not appear as well-defined due to reflection, scattering, and attenuation. Reflection is caused by the soundwaves bouncing off the surface of a structure in a given direction. Scattering occurs when the soundwaves is reflected in multiple directions. Attenuation is the loss of sound energy as it penetrates different tissue densities. Some of the sound waves are absorbed.

Figure 3: Basics of Ultrasound Imaging. A is the striations of the deltoid muscle. B is the hyperechoic surface of the humerus.

The type of soundhead will determine the view seen. Linear soundheads show a rectangular view as in Figure 3 and a curvilinear soundhead will display a triangular-shaped view as typically seen with US of the growing fetus as in Figure 4. There are adjustments in gain and magnification to help improve the clarity of the image or focus on certain depths, respectively.

Figure 4: Fetal Ultrasound Imaging

1.2.3: Ultrasound Characteristics of Vessels, Nerve, Muscle, and Bone

Blood vessels are seen as a hollow tube with anechoic, black lumen (Figure 5). The outer layers of the vessel wall will vary in shade based on the density of its components but are often unidentifiable in arterioles and venules. Large arteries have more connective tissue and muscle in the outer wall, so this area will reflect sound waves back to the transducer.

Depending on the angle of the slice, the vessel my look like a circle, oval, or a linear tube.

Consider what a straw would look like if it were cut perpendicular to its length, longitudinally, or at an oblique angle to its length. Arteries can often be distinguished from veins by adding pressure to the probe. The veins will compress easily while the arteries will often hold shape.

Pulsing of the artery can also be used to distinguish it from veins.

Nerves have a characteristic honeycomb sign with hyperechoic spots within a hypoechoic center when the slice is perpendicular to the long axis of the nerve as seen in 9

Figures 3 and 5. However, much like arteries and veins, the shape of a nerve will depend on the angle of the slice. A longitudinal view of a nerve will show stacks of hyperechoic layers of perineurium with the outer connective tissue of large nerves showing the brightest due to the connective tissue of the epineurium. The hyperechoic portions represent the soundwaves reflecting off the density of the perineurium and epineurium (Lawande et al., 2014). Nerves are not easily compressible and often run near blood vessels.

Shadow created by humerus

Figure 5: Characteristics of Vessels and Nerves. “A” and “V” point to the posterior circumflex humeral artery and vein, respectively. “N” points to the honeycomb shape of the axillary nerve.

Skeletal muscle is very easy to identify by the layered bands of hyperechoic fascicles.

Muscle structure can be identified by the angles of the fascicles to compare pennated versus fusiform muscle groups. Fascial planes can be identified between muscles as bright, hyperechoic images with no shadow effect in the far field. Often, nerves and blood vessels are found running within these fascial planes.

Bone has a hyperechoic surface with a shadow effect in the far field. This is due to the sound waves reflecting back to the transducer. The bone surface does not allow additional sound to travel beyond the bony surfaces (Figure 5).

1.3: Research Design

Chapter 2 will review the pertinent background including the embryologic development of the upper extremity, typical anatomy of the shoulder girdle, common injuries to the shoulder that may impact function most notably proximal humerus fractures, and the surgical procedures to correct pathology associated with these injuries. The remaining portion of the manuscript is divided into a series of studies that contribute to the body of knowledge associated with anatomical variation important for surgeons to understand when operating around this joint, written separately.

The first goal of this portion of the study was to determine if there is a difference in vertical positioning of the AN as it travels around the humerus. The importance of this variability lies in planning surgical interventions of the proximal humerus, rotator cuff, and glenohumeral joint. The highlight procedures include percutaneous reduction of proximal humerus fractures, trans-cortical biceps tenodesis, and deltopectoral approach to various surgical procedures. Once we understand the typical position along the course of the nerve, it 11 may be helpful to screen for its location utilizing real-time ultrasound imaging or use it to visualize the nerve when placing locking screws to reduce the fracture.

The second goal of this study is to compare the relative position of the cadaver dissections with the position visualized through US in order to determine the feasibility of intraoperative utilization. The final portion of the study is an investigation into the frequency of lateral pectoral nerve branching to supply the anterior deltoid as it may cross the deltopectoral groove making it vulnerable to transection during this approach to the shoulder. The following research questions and hypotheses were investigated:

1.3.1: Chapter 3: A cadaver dissection comparing the vertical position of the axillary nerve along its course

Aim: To compare the vertical position of the axillary nerve along its course from the exit through the quadrangular space to the termination in the anterior deltoid by embalmed cadaver dissection

Research Question #1:

Does the AN vary in vertical displacement from typical surgical bony

landmarks along its course between posterior, lateral, and anterior divisions?

Hypothesis 1:

H1: There is a difference between sides of the body for each of the three test

positions (anterior, lateral, posterior divisions)

H0: There is no a difference in vertical position between sides of the body at

each of the three test positions (anterior, lateral, posterior divisions)

Hypothesis 2:

H1: There is a difference in vertical position between test positions

H0: There is no difference in vertical position between all six test positions

Research Question #2:

Does the AN terminate nearer than two centimeters from the medial border

of the deltoid increasing the risk of injury during deltopectoral surgical

approaches to the shoulder

Hypothesis 1:

H1: The AN terminates nearer than two centimeters from the medial border

of the deltoid.

H0: The AN does not terminate within two centimeters of the medial border

of the deltoid.

1.3.2: Chapter 4: Comparing the Ultrasound location of the Axillary Nerve to Cadaver

Dissection: A Feasibility Study

Aim: To compare the vertical position of the AN measured from a common location between fresh cadaver dissection and ultrasound imaging.

Research Question #1:

Can the location of the axillary nerve be identified accurately via ultrasound

imaging?

Hypothesis 1:

H1: There is a difference between the ultrasound-derived location of the AN and

the cadaver dissection on the same subject.

H0: There is no difference between the ultrasound-derived location of the AN

and the cadaver dissection on the same subject.

1.3.3: Chapter 5: Location of the Axillary Nerve along its course via Ultrasound Imaging

Aim: To compare the vertical position of the axillary nerve along its course from the exit through the quadrangular space to the termination in the anterior deltoid by ultrasound imaging of healthy volunteers

Research Question #1:

Does the AN vary in vertical displacement from bony landmarks along its

course between posterior, lateral, and anterior divisions via ultrasound

imaging?

Hypothesis 1:

H1: There is a difference between sides of the body for each of the three test

positions (anterior, lateral, posterior divisions)

H0: There is no a difference in vertical position between sides of the body at

each of the three test positions (anterior, lateral, posterior divisions)

Hypothesis 2:

H1: There is a difference in vertical position between test positions

H0: There is no difference in vertical position between all six test positions

1.3.4: Chapter 6: Accessory Innervation of the Anterior Deltoid from the Lateral Pectoral

Nerve

Aim: The aim of this portion is to determine the prevalence of nerve supply to the anterior deltoid from the lateral pectoral nerve. Accessory innervation of the anterior deltoid has been described in case studies previously, but no specific frequency of occurrence has been established.

Research Question:

Does the lateral pectoral nerve send branches to the anterior deltoid?

Hypothesis 1:

H0: The lateral pectoral nerve does not supply innervation to the anterior

deltoid

H1: The lateral pectoral nerve supplies a branch to the anterior deltoid

1.4: Significance and Future Directions

This study contributes to the body of knowledge regarding the location of the axillary nerve as it travels around the surgical neck of the humerus. Much like previous studies, the data suggests the majority of nerves are located within the safe zone of 5-7 centimeters from the bony landmarks. However, there are several measurements that show some nerves do fall in a location outside the safe zone. These are the nerves that most concern the surgeon.

This study is a first step in determining the feasibility and usefulness of ultrasound imaging in the operating room for identifying vulnerable structures. A significant portion of the operating time is spent identifying landmarks and retracting them out of the way. In fact, some

15 surgeons choose approaches to specifically avoid these structures though the approach may not be the most desirable.

Regarding proximal humerus fractures, it appears ultrasound may be valuable at locating the axillary nerve when placing locking screws into the plate much like ultrasound is used to track the needle in order to bathe peripheral nerves with local anesthetic. The most vulnerable screws are those placed to correct the valgus deformity resulting from fracture at the surgical neck, given the typical location of the axillary nerve in this area.

Future studies are necessary to improve the statistical power to allow more generalizability of the results. It would also be beneficial to utilize ultrasound imaging while performing these procedures on cadavers to determine the risk of injury to the axillary nerve.

Simulated proximal humerus fractures may be reduced while using ultrasound guidance for placement of percutaneous screws on cadavers to identify accuracy of this method.

1.5: Conclusion

It is often difficult for surgeons to change the way they perform common procedures unless there is substantial evidence to support the potential for improvement in outcomes. This study does not provide a strong basis for changing patterns. However, there is promise that ultrasound may aide the surgeon in utilizing a less invasive technique while providing a structurally sound reduction of proximal humerus fractures. This is a first step to potentially modify surgical approaches to the shoulder. Additional studies utilizing ultrasound while performing these procedures on cadavers may provide additional evidence for its utility.

Chapter 2: Shoulder Girdle and Upper Extremity: Anatomy, Injury, and Reconstruction

The shoulder girdle and upper extremity, consisting of the clavicle, scapula, humerus, radius, ulna, and the eight bones of the wrist and the nineteen bones of the hand, contribute substantially to human function and performance. The structural anatomy is rivaled by the complex functional mechanics of the shoulder and upper extremity. To fully understand the mechanisms of upper extremity movement, it is important to recognize the embryologic development, the bony and muscular anatomy, and the functional interaction of these components. This chapter will emphasize the shoulder girdle with minimal discussion regarding the distal portion of the upper extremity.

2.1: Embryologic Development

The embryologic development of the human is defined as the first eight weeks of development, beginning at conception. Growth beyond the first eight weeks is considered the fetal period and continues until birth. The embryological development phase is the time period when body structures are defined while the fetal period contributes to the growth and maturation of these body structures in order to become functioning components of the body systems. Somites begin to condense from the mesenchymal tissue of the sclerotomes during the third week and will develop into the axial skeleton and its musculature (Moore et al., 2008).

Mesenchymal tissue cells from the mesoderm begin to proliferate and coordinate the development of the appendicular skeleton including the upper limb buds by day 26 or 27 of development (Moore et al., 2008). Over the next week, the limb buds flatten out like paddles and expand to form the terminal ends of each limb. These flattened limbs further differentiate

17 with digital notches around week seven. At this time, there will be spontaneous movements of the upper limbs.

Mesenchymal bone models begin chondrification to form hyaline cartilage at week six and begin endochondral ossification by week 8. Primary ossification centers in the diaphysis of long bones starts at various times for each long bone but nearly all will be present by the 12th week. Typically, only the distal end of the femur and proximal end of the tibia secondary ossification centers are present in the epiphysis at birth (Moore et al., 2008). Synovial joints are formed by breakdown of intervening mesenchymal cells between the long bones. These joints are typically recognizable by week 8 (Moore et al., 2008).

The muscles of the extremities are derived from myogenic precursor cells of the mesoderm that surround the bone. Islands of myogenic cells condense into myotubes and further into myofilaments and myofibrils during fetal development (Moore, et al., 2008). This formation pattern contributes to the occasional fusion of some muscles during development.

For instance, the clavicular portion of the pectoralis major and anterior deltoid have been shown to fuse making it difficult to differentiate the division (Barberini F, 2014; Soni S et al.,

2008).

2.2: Anatomy of the Shoulder Girdle

The anatomy of the shoulder girdle can be divided into structural and functional components. The structural anatomy includes the bones, joints, nerves, and blood vessels defining the surface and musculoskeletal anatomy. The functional components can be described as the interaction between these structures in order to evaluate movement pathology or dyskinesia of the joints. 18

2.2.1: Surface Anatomy

The surface anatomy of the shoulder girdle defines borders and landmarks of deeper structures including muscle, tendon, and bone. When reviewing the surface anatomy, it is valuable to have a systematic approach to the visual and palpation scan. Typically, the first item to note is the static posture of the scapula. The medial border of the scapula should rest against the dorsal surface of the ribcage. The spine of the scapula should angle slightly superior to the horizontal from medial to lateral. Kibler et al. (1991) described three abnormal positions of the scapula that relate to muscular imbalances in strength or length and correspond to expected pathology (Burkhart et al., 2003). Figure 6 demonstrates type one, two, and three winging patterns. The relative side to side comparison of muscle size is the second item to scan. The contours of the upper trapezius, the full breadth of the deltoid, and the volume of the pectoralis major are compared for potential deficits. Figures 7 and 8 show the typical surface anatomy of the shoulder girdle of both the anterior and posterior views. Further, particularly for the clinician, palpation of specific structures is utilized to help pinpoint to location of pathology. A typical palpation scan of the shoulder scan includes bone and soft tissue anatomy as the clinician attempts to define tenderness.

Figure 6: Kibler scapular dyskinesia. Slide A shows the inferior angle type. Slide B shows the medial border type. Slide C shows the superior border or “shrug” type. (Image from www.sciencedirect.com accessed 3/10/2018)

UT D

T R I

Figure 7: Posterior View. T-triceps, L-latissimus dorsi, UT-upper trapezius, D-deltoid, I-infraspinatus, R-rhomboids Major/Minor, Dotted blue line-spine of the scapula

UT AD

B PM T

Figure 8: Anterior View. AD-anterior deltoid, UT-upper trapezius, PM-pectoralis major, B-biceps brachii, T-triceps brachii

2.2.2: Musculoskeletal Anatomy

The shoulder girdle consists of three bones: the clavicle, the scapula, and the humerus.

Figure 9 and 10 display the shape and contours of these bones with typical muscular attachment. The clavicle is an S-shaped, flat bone that connects the manubrium to the scapula.

The pectoralis major and deltoid originate for its anterior surface. The subclavius muscle originates from the undersurface of the medial end of the clavicle to attach to the ribs. The trapezius inserts on a portion of the lateral end of the clavicle.

The scapula supports the origin and insertion of many muscles to help control the dynamic movements of the upper extremity and shoulder girdle. It is a triangular-shaped, flat bone with unique projections including the coracoid process and acromion. The scapula articulatesB with the clavicle at the acromioclavicular joint and the humerus at the glenohumeral joint. The scapulothoracic “joint” between the scapula and the ribs is not a true joint but is described more by the functional interaction as it relates to upper extremity movement.

LHB GT S Clavicle LT

Sub

Figure 9: Proximal Humerus with long head of biceps Figure 10: Anterior View of the Scapula. S- (LHB). LT-lesser tuberosity, GT-greater tuberosity, supraspinatus, TM-teres major, Sub-subscapularis. Blue line indicates anatomic neck, Red line indicates surgical neck

The pectoralis major is divided into three portions based on the origin medially on the anterior chest wall. The clavicular, sternal, and abdominal portions originate from the medial one-third of the clavicle, the sternum, and the abdominal aponeurosis, respectively. It inserts onto the medial border of the greater tuberosity. It is a strong adductor and internal rotator of the humerus. The pectoralis minor originates medially on ribs 3-5 and attaches to the coracoid process of the scapula. The pectoralis minor is often tight, causing the scapula to tip anteriorly.

The latissimus dorsi is a large, fan-shaped muscle originating from the thoracic spine levels four through eight and the thoracolumbar fascia. It inserts into the humerus at the medial side of the bicipital groove. The latissimus dorsi is a strong extender and internal rotator of the humerus.

The trapezius muscle extends from the nuchal lines on the posterior skull, along the spinous processes of the cervical and thoracic vertebrae. It attaches laterally along the spine of

22 the scapula. The trapezius is often divided into functional portions, the upper, middle, and lower, that produce elevation, retraction, and upward rotation of the scapula, respectively.

The serratus anterior is important for protraction of the scapula and upward rotation of the glenoid. It originates from the lateral border of ribs two through eight and inserts onto the medial border of the scapula. The serratus anterior is often deficient in “winging” of the scapula, typically a type one or two (Burkhart et al., 2003).

There are four rotator cuff muscles all originating on the surface of the scapula to insert onto the proximal humerus with a collective goal of maintaining the humeral head on the glenoid including the subscapularis, supraspinatus, infraspinatus, and teres minor. The broadest and strongest of these is the subscapularis on the anterior surface of the scapula (Figure 10). It inserts onto the lesser tuberosity of the humerus to produce internal rotation. The supraspinatus fills the supraspinatus fossa of the scapula and inserts onto the anterosuperior surface of the greater tuberosity on the superior facet. Its primary role is to initiate humeral abduction and assist in depression of the humeral head during elevation. The infraspinatus occupies the inferior side (posterior) of the scapular spine to insert onto the superior margin of the greater tuberosity just posterior to the supraspinatus at the middle facet and produce the most external rotation force of the humerus (Figure 11). The teres minor is a lessor external rotator of the humerus, extending from the lateral border of the scapula to insert onto the posterosuperior portion of the greater tuberosity onto the inferior facet.

I Tm

Figure 11: Posterior View of the Scapula. S-supraspinatus, I-infraspinatus, Tm-teres minor, TM-teres major

The primary focus of this manuscript is the innervation of the deltoid muscle. It originates along the lateral clavicle, the acromion and spine of the scapula to insert on the deltoid tuberosity midway down the lateral surface of the humerus. This is a triangular-shaped muscle often divided into functional thirds; anterior, lateral, and posterior. A general description of each muscle group around the clavicle and scapula is presented in Table 1.

Muscle Innervation (cord Proximal Distal Primary Action levels) Attachment/Origin Attachment/Insertion Pectoralis Major Medial and Lateral Medial Half of Lateral border of Adduct and Pectoral Nerves clavicle, bicipital groove internally rotate (C5-T1) manubrium, the humerus sternum, first six ribs, abdominal aponeurosis Pectoralis Minor Medial Pectoral Ribs 3-5 Coracoid Process of Stabilizes the Nerve (C8, T1) the Scapula scapula Serratus Anterior Long Thoracic Lateral surface of Medial border of the Protracts and Nerve (C5-7) first 8 ribs scapula upwardly rotates the scapula Table 1: Muscles of the shoulder complex including innervation, attachments, and primary action.

Trapezius Spinal Accessory Superior nuchal Lateral clavicle, Elevates, retracts, Nerve (CN XI) line, nuchal acromion and spine of upwardly rotates ligament, and SP of scapula glenoid T7-12 Latissimus Dorsi Thoracodorsal SP of T6-12, Base of bicipital Extends, adducts, Nerve (C6-8) thoracolumbar groove and internally fascia, iliac crest rotates humerus Rhomboid Dorsal Scapular M: SP of T2-5 M: Med border of Scapular retraction Maj/minor Nerve (C4-5) m: nuchal ligament scap and downward SP C7-T1. m: Med border rotation of the scapula at spine glenoid Deltoid Axillary Nerve Lateral third of Deltoid tuberosity of Abduction of (C5,C6) clavicle, acromion, humerus humerus. Anterior and spine of scapula will flex and horizontally adduct humerus, Posterior will extend and horizontally abduct the humerus Supraspinatus Suprascapular Supraspinatus Fossa Greater tuberosity of Initiates humeral Nerve (C4-6) humerus abduction Infraspinatus Suprascapular Infraspinatus Fossa Greater tuberosity of External rotation of Nerve (C5-6) humerus humerus Subscapularis Upper and Lower Subscapular Fossa Lesser tuberosity of Internal rotation of Subscapular Nerve humerus humerus C5-7) Teres Minor Axillary Nerve (C5- Lateral border of Greater tuberosity External rotation of 6) scapula humerus Teres Major Lower Subscapular Inferior Angle of Medial border of Adduction and Nerve (C5-6) Scapula bicipital groove internal rotation of humerus Table 1: Muscles of the shoulder complex including innervation, attachments, and primary action (continued)

2.2.3: Joint Anatomy

There are three main joints of the shoulder girdle including the sternoclavicular joint, the acromioclavicular joint, and the glenohumeral joint. The sternoclavicular joint is the articulation between the manubrium of the sternum and the medial end of the clavicle. It is a diarthrosis, synovial joint with a fibrocartilaginous disc. This is the only bony connection between the shoulder girdle and the axial skeleton. The clavicle rotates, translates anteriorly

25 and posteriorly, and elevates at this joint. The remaining connections to the trunk are muscular and require dynamic control.

The distal end of the clavicle articulates with the acromion of the scapula to form the acromioclavicular joint. This is a plane synovial joint with ligamentous thickenings of the joint capsule on the superior and inferior margins as seen in Figure 12. This joint is further supported by a ligament complex arising from the coracoid process as shown in Figure 12, specifically the conoid and trapezoid ligaments. The scapula will pivot around the joint to allow for internal and external rotation of the body and upward and downward rotation of the glenoid.

1 2 3

Figure 12: Anterior View of the Acromioclavicular joint. 1-Coracoacromial ligament. 2 and 3- coracoclavicular ligaments including trapezoid and conoid ligaments, respectively.

The most complex joint of the shoulder girdle is the glenohumeral joint between the glenoid fossa of the lateral border of the scapula and the humeral head. Inherently unstable due to the many degrees of freedom for movement, the glenohumeral joint has a very shallow

26 socket surrounded by the glenoid labrum. The ligamentous support of this joint are primarily thickenings of the joint capsule concentrated at various positions around the circumference of the joint.

2.2.4: Neuroanatomy of the Brachial Plexus

The brachial plexus is a coordinated network of branching nerves that supply motor and sensory innervation to portions of the trunk and the upper extremity. Originating primarily from spinal cord levels C5 through T1, it is divided into segments beginning with the roots, progressing through the trunks, divisions, cords, branches, and ending in the terminal branches.

Many students recall this segmentation by the mnemonic “Randy Travis Drinks Cold Beer.” The lateral pectoral nerve and the axillary nerve are of particular interest to this study and will be described next.

Pectoral Nerves:

The pectoral nerves have been investigated to determine the extent of branching to supply the pectoralis major and minor muscles (Porzionato et al., 2012; Solomon et al., 1997;

Corten et al., 2003; Aszmann et al., 2000; Beheiry, 2012; Lee, 2007; Macchi et al., 2007). Two main pectoral nerves are named by their branching off the brachial plexus. The medial pectoral nerve (MPN), known also as the internal anterior thoracic nerve and the nerve thoracicus ventralis II, arises from either the medial cord (49.3%) or the anterior division of the lower trunk

(43.8%) to wrap around the posterior side of the lateral thoracic artery just distal to the thoracoacromial trunk (60%) (Porzionato et al., 2012; Solomon et al., 1997; Macchi et al., 2007) .

It consists mainly of C8 and T1 cord levels (78%) to innervate the sternal and costal portion of

27 the pectoralis major (Lee, 2007; Porzionato et al., 2012). In addition, it supplies the pectoralis minor at the third intercostal space on the mid-clavicular line as it travels either through it as one nerve (22%), through it and around it as two separate nerves (32%), or around the lateral surface as one nerve (38%) while giving branches to innervate it (Porzionato et al., 2012;

Aszmann et al., 2000; Beheiry, 2012; Lee, 2007; Macchi et al., 2007).

The lateral pectoral nerve (LPN), also known as the external anterior thoracic nerve, lateral anterior thoracic nerve, nerve thoracicus ventralis I, has a more inconsistent exit from the brachial plexus containing C5-7 (50%) or C6-7 (50%) cord levels (Porzionato et al., 2012;

Solomon et al., 1997; Corten et al., 2003; Aszmann et al., 2000; Beheiry, 2012; Lee, 2007; Macchi et al., 2007). It arises variably from the anterior division of the upper (7.1%) or middle (9.9%) trunks, from both the upper and middle trunks (33.8%), the lateral cord (23%), or a portion of all the above (Porzionato et al., 2012; Solomon et al., 1997; Macchi et al., 2007). After combining to form one LPN, it crosses anterior to the axillary artery to run a straight course with the pectoral branches of the thoracoacromial trunk (Solomon et al., 1997; Macchi et al., 2007). The

LPN divides into two primary branches. The superficial, or ventral, division supplies the clavicular head of the pectoralis major via a medial and lateral branch and the deep, or dorsal, division innervates the medial clavicular and sternal portions of the pectoralis major. The LPN and MPN combine to form an ansa pectoralis consisting of a variety of combination of C5-C7.

The location of this ansa is quite variable or may not exist at all. There have been various sensory functions associated with the LPN including temperature, pain and proprioception of the subacromial bursa, the coracoclavicular ligaments, the shoulder joint, the periosteum of the clavicle, while providing touch and temperature sensation to the skin over the anterior deltoid

(Akita et al., 2002). The distribution of these sensory functions for the LPN have similar courses as the branches of the thoracoacromial trunk, particularly the acromial and deltoid branches.

Axillary Nerve:

The axillary nerve (AN) contains nerve fibers primarily from the C5 and C6 nerve roots of the brachial plexus (Loukas et al., 2009). Branching from the posterior cord as one of its two main terminal branches (radial nerve being the other), the AN travels deep to the coracoid process and conjoined tendon and wraps around the inferior border of the glenoid neck adjacent to the inferior glenohumeral joint capsule to exit through the quadrangular (or quadrilateral) space bordered by the teres minor superiorly, the teres major inferiorly, the long head of the triceps medially and the surgical neck of the humerus laterally (Figure 13).

The AN divides into anterior and posterior divisions. More frequently, this division occurs within the quadrangular space (65% of the time) and less frequently (35% of the time) occurs more distally, within the deltoid itself (Loukas et al., 2009).

Quadrangular Space

LHT

Figure 13: Quadrangular Space. Tm-teres minor, LHT-Long Head Triceps Brachii

The anterior division of the AN continues anteromedially around the humeral neck on the deep surface of the deltoid to supply the middle (6 secondary branches) and anterior (2 secondary branches) portions (Stecco et al., 2010). The branching pattern of the main trunks within the deltoid muscle has been investigated extensively to determine the risk of damage during traumatic injury and surgical reconstruction, particularly with proximal humerus fractures. Peker et al. (2005) described branching patterns that match the shape of the muscle.

The main trunks typically enter the muscle at a near perpendicular angle to the muscle fibers.

The minor and terminal branches generally run in a parallel course with the muscle fibers. Given the triangular shape of the deltoid, the terminal branches of each division should turn and travel in a proximal direction, in line with the muscle fibers. Therefore, the studies describing the position of the AN within the deltoid may not account for the regional differences in location of

30 the terminal branches. One would suspect a slight proximal/superior migration of the distal portion of the AN as it terminates in the anterior deltoid. The extent of this superior migration has not yet been quantified.

2.2.5: Functional Anatomy

The deltoid is a primary elevator of the humerus into both flexion and abduction with innervation from the axillary nerve (Moore et al., 2007). It has a strong mechanical advantage for lifting and reaching over shoulder height once the humerus elevates greater the 30 degrees from the vertical in the frontal plane, an action controlled by the supraspinatus. Loss of axillary nerve innervation of the deltoid results in significant movement dysfunction of the shoulder joint and may result in the common “shrug sign’, a compensation for humeral elevation by the scapula (Figure 6). This can also be seen with the Akimbo test (Fujihara et al., 2012). The patient is simply asked to place the hands on the iliac crest. Loss of axillary nerve function does not allow the deltoid to abduct the arm to enable placing the hands onto the iliac crests.

The AN does innervate the teres minor via a branch off the posterior division. Loss of function of the teres minor will result in weakness of external rotation of the shoulder though complete loss of strength is not realized due to the difference in cross-sectional area compared to the infraspinatus, which contributes the majority of external rotation strength (Kronberg et al., 1990).

In addition to motor supply at the shoulder joint, the AN provides some superolateral shoulder sensation. A common way to test for AN integrity is to brush the surface of the skin to examine the presence of sensation to light touch in the area known as the “regimental badge” over the antero-lateral deltoid carried by the superior lateral brachial cutaneous nerve.

The pectoralis major is a powerful adductor of the humerus in both the frontal and transverse planes. It draws innervation from the lateral pectoral and medial pectoral nerves.

We use the pectoralis major to push ourselves up from a prone position, to hug someone, and to push luggage into the overhead bin of an airplane. The clavicular head of the pectoralis major and the anterior portion of the deltoid share fiber orientation, proximity of attachments, and, therefore, functional movements.

The pectoralis minor plays a stabilizing role for the scapula with innervation primarily from the medial pectoral nerve. Through the attachment on the coracoid process, the pectoralis minor tips the scapula anteriorly along a transverse access, downwardly rotates the glenoid, and will also internally rotate the scapula along a superior-inferior access. Tightness of the pectoralis minor contributes to impingement episodes of the rotator cuff (Wei Dong, 2015).

2.3: Common Injuries of the Shoulder Girdle

Injury to the shoulder joint is fairly common in most all age groups though there is variability in the type of injury typically sustained. For instance, younger individuals (teenagers and young adults) typically have injuries related to instability or dislocation while order individuals (greater than fifty) may sustain proximal humerus fractures (Kroner et al., 1989; Karl et al., 2015; Roux et al., 2012). Middle-aged individuals typically encounter injuries to the rotator cuff or may develop adhesive capsulitis, often diagnosed as “Frozen Shoulder” (Diaz et al., 2005). Injuries related to the axillary nerve are presented.

2.3.1: Dislocations/Subluxations

It is common for inferior glenohumeral dislocations to cause a stretch injury to the AN resulting in weakness and paresthesia. This occurs in 9-18% of all dislocations (Lee et al., 2011) in addition to labral pathology and failure of the ligamentous support structure. The AN wraps inferiorly around the glenoid as it travels in an anterior to posterior direction aiming towards the quadrangular space. In inferior dislocations, the head of the humerus will disengage the glenoid and fall over the lip to rest in either an anterior or posterior position. This changes the relative length of the AN creating a traction injury.

It is estimated that the AN is damaged in 6-42% of all brachial plexus injuries (Loukas et al., 2009; Stecco et al., 2010; Uz et al., 2007; Lee et al., 2011). Some of these injuries occur at birth and result in Erb’s Palsy, a traction injury to the brachial plexus while the newborn exits the birth canal. The extent of injury and functional loss associated with Erb’s Palsy is variable, depending on the degree of damage to the plexus (Evans-Jones et al., 2003).

The axillary nerve is also vulnerable to compression within the quadrangular space resulting in “Quadrangular Space Syndrome”, typically with overhead athletes (Lee et al., 2011;

Lester et al., 1999). Athletes can develop hypertrophy of the triceps and teres major/minor resulting in narrowing of the quadrangular space. Fortunately, the symptoms may be transient based on activity level (Lester et al., 1999).

Acromioclavicular (AC) separation or subluxations typically occur when falling on the lateral shoulder (Moore, Agur, 2007). The compressive force of the acromion on the distal clavicle damages the AC ligaments and more severely the coracoclavicular ligaments. These injuries are graded 1-6 depending on the amount of displacement and the number of ligaments damaged utilizing the Rockwood Classification scheme (Rockwood, 1985). Low grade injury

33 results in minimal to no displacement of the distal clavicle. However, high grade injury with damage to the coracoclavicular ligaments results in instability of the distal end of the clavicle known as a piano key sign (Magee, 1997)

2.3.2: Neer Classification of Proximal Humerus Fractures

Proximal humerus fractures, on the other hand, account for 4-6% of all fractures and are one of the most common ways to damage the axillary nerve (Saran et al., 2010). Multiple fracture patterns occur in the proximal humerus making understanding of the location of the AN critical for post-fracture decision making. The fracture patterns of the proximal humerus were most notably reported by Neer and are the standard for describing current injuries (Neer, 1970;

Carofino, Leopold, 2013). The threshold for displacement is typically 1 cm or angulation greater than 45 degrees though some factors may influence the surgeon to surgically stabilize the fracture, including age, angulation, and extremity dominance. One-part fractures have no fragment that meets the threshold for displacement but may have more than one fracture site.

Two-part fractures include one fragment that is displaced including the tuberosities or head at the surgical or anatomical necks. One- and two-part fractures can often be managed conservatively with immobilization provided there is minimal to no displacement. In these types of fractures, the risk of non-union is generally low since the fracture surfaces are in close proximity. Three-part fractures feature a displaced tuberosity in addition to a surgical neck fracture that is displaced or angled greater than 45 degrees. Four-part fractures result in displacement of all four segments including both tuberosities, the articular head, and humeral shaft. With the multiple fragments being displaced in four-part fractures, there is higher incidence of avascular necrosis (AVN) (Campochiaro et al., 2015). Due to the risk of AVN and

34 non-union, these fracture patterns are often treated with hemiarthroplasty instead of open- reduction internal fixation (ORIF). Figure 14 differentiates the classifications of proximal humerus fractures. It is extremely important to understand the path of the AN in order to avoid injury during open surgical reconstruction or transcutaneous reduction of fractures. The choice of surgical approach is often dictated by physician experience and preference as to closely approximate the fragments. Failure to secure adequate reduction is the primary reason for avascular necrosis (Campochiaro et al., 2015). This is the area of most debate when deciding which surgical approach to use for reduction of the fracture and these surgical procedures will be described in subsequent sections.

Figure 14: Neer Classification of Proximal Humerus Fractures (Neer, 1970).

2.3.3: Muscle/Tendon Injuries

The primary muscle/tendon injury to the shoulder girdle is rotator cuff pathology.

Ranging from tendinitis to complete tear, the rotator cuff tendinopathy can significantly limit upper extremity function and sleep patterns. Rotator cuff repair has transitioned from a fully open procedure requiring deltoid reflection to a mini-open, lateral deltoid split approach, and currently, most procedures are completed arthroscopically limiting the vulnerability of the AN.

2.4: Operative Management of the Axillary Nerve for Shoulder Injuries

Not only can the AN be damaged by the fracture, the AN is vulnerable throughout the operative management due to its location around the surgical neck and may incur an iatrogenic injury. The course around the humerus makes it vulnerable during a variety of procedures in addition to treatment of proximal humerus fractures, including, but not limited to, biceps tenodesis and a superior approach to total shoulder arthroplasty commonly performed in

Europe.

2.4.1: Proximal Humerus Fractures

The main concern for surgical management of type three proximal humerus fractures is avoiding damage to the axillary nerve. For all procedures, significant surgical time is used to locate and protect the AN as it travels around the proximal humerus as the “safe zone” is not a reliable reference as previously discussed. The surgeon has at least three options for management of these fractures, a deltopectoral approach, lateral deltoid split approach, and a mini-open deltoid splitting approach.

The deltopectoral approach is the most conservative in nature as the AN can be directly visualized and tagged to protect when placing the locking plate. A longitudinal incision is carried through the skin at approximately the coracoid process or more laterally at the anterior edge of the AC joint. The inferior termination of this incision is dependent on the amount of exposure necessary for the given procedure. For instance, the incision may need to extend more inferiorly for a proximal humerus fracture with a surgical neck component versus a pectoralis major repair. Within the subcutaneous tissue, the cephalic vein is identified and directed out of the field. The surgeon will bluntly identify the septum between the anterior deltoid and 37 pectoralis major to separate this plane. The anterior deltoid is retracted laterally to improve the window for visualizing the deeper structures. This provides direct visualization of the conjoint tendon, the subscapularis tendon. The surgeon as able to locate the neurovascular bundle containing the AN and PCHA on the under-surface of the deltoid. Despite direct visualization of the neurovascular bundle, prolonged retraction of the nerve may still contribute to variant nerve injury (Apaydin et al., 2010; Traver et al., 2016; Westphal et al., 2017). In addition, this procedure does create the largest incision and may contribute to unsatisfactory scar.

A lateral deltoid spitting approach, as the name implies, carries the incision more laterally than the deltopectoral groove. It is typically located off the anterolateral edge of the acromion. The vulnerability of the AN increases with this procedure as the surgeon cannot directly visualize its location. An incision carried too far inferiorly may inadvertently transect the

AN. Therefore, these incisions are often short of the desired exposure creating a blind spot for placement of locking screws for plate fixation in PHF. Once the incision is complete, retractors are often placed within the field to keep the borders of the deltoid split open for ease of visualization. As described above, retractors may place traction on the AN resulting in damage.

The mini-open proximal humerus approach reduces the size of the incision while limiting visualization of the AN. The mini-open is a modification of the lateral deltoid split minimizing the inferior migration of the split by more than fifty percent. Despite careful consideration,

Westphal et al. (2017) described iatrogenic nerve injuries associated with this approach. For

PHF, the surgeon will feed the locking plate inferiorly down the surface of the humerus to fit deep to the neurovascular bundle. This is a “blind” procedure, in regard to the AN, as the surgeon will either predict its vertical location or extend the long finger deep to the deltoid and palpate the neurovascular bundle. The main risk for this approach involves the positioning of

38 the surgical neck screws for correcting the angulation of the fracture that are typically located at the predicted level of the AN. These are often placed percutaneously through very small lateral incisions. An intermedullary rod may be placed for humeral shaft fractures with a mini-open approach. Although the placement of the rod is of minor concern for damage to neurovascular structures, the AN is at risk when placing the locking screws percutaneously. Ultrasound confirmation of the AN location may allow the surgeon to locate the surgical neck screws in a more optimal position to improve reduction of the fracture angulation. Intraoperative US imaging may be a valuable tool for improving procedure time and for decreasing risk of injury resulting from prolonged tensioning, compression, or penetration of the nerve.

2.4.2: Bi-cortical Biceps Tenodesis

Historically the biceps tenodesis would be fixed within the bicipital groove with either suture anchors or an interference screw (Mazzocca et al., 2005). Recently, to improve the length-tension relationship of the muscle and improve pull-out strength, a bicortical fixation placed subpectorally has been described (Ding et al., 2014). The position inferior to the pectoralis major tendon does increase the risk of accessing the AN, especially posteriorly, if the surgeon is not careful of the angulation of the tunnel. The AN may lie within two centimeter of the posterior cortical hole making surgical precision a necessity (Saithna et al., 2017). The benefits of this type of procedure include ease of accessibility in regards to the local anatomy, a small incision and short surgical time, and removal of nearly the entire tendon and sheath that may contribute to prolonged symptoms

(https://www.healio.com/orthopedics/arthroscopy/news/print/orthopedics- today/%7B95443cbd-bc23-4f6a-adfb-0f4df8a0330b%7D/surgical-technique-arthroscopic-and-

39 subpectoral-long-head-of-biceps-tenodesis. Accessed 2/10/2018). Real-time US for evaluation of the course of the AN posteriorly may assist the surgeon in positioning the bone tunnel more confidently, thereby shortening the surgical time and limiting risk of injury.

2.4.3: Superior approach to Total Shoulder Arthroplasty

The anterosuperior approach to total shoulder arthroplasty, first described in 1993, is an alternative to the deltopectoral approach with a few advantages including simplicity, more direct exposure of the glenoid, and preservation of the subscapularis (Mackenzie, 1993).

However, the chief risk of this procedure is AN palsy (Mole et al., 2011). Although not a common approach in the United States, the anterosuperior approach is often used in Europe as the primary exposure for total shoulder arthroplasty. This procedure is not unlike the mini-open rotator cuff procedure performed with a deltoid splitting just off the anterolateral edge of the acromion. However, since the incision is carried more inferiorly, the risk to the AN increases.

US imaging may be of great value during this surgical procedure in order to limit the damage to the AN.

Chapter 3: A cadaver dissection comparing the vertical position of the axillary nerve along its

course.

3.1: Abstract

The axillary nerve (AN) is of great concern when performing surgery in and around the glenohumeral joint. There is variability in the methods to measure the distance from the acromion, so the reliability of the anatomic safe zone is limited. The purpose of the present study is to compare the vertical position of the axillary nerve as it relates to the origin of the deltoid along the clavicle and scapula. Ten embalmed cadavers were available for dissection of the axillary nerve. The proximal attachment of the deltoid was sharply debrided and reflected inferiorly. The overall length of the deltoid origin was measured using a flexible tape measure to determine the anatomic thirds. The distance between the proximal bony attachment of the deltoid and the axillary nerve was measured at three positions corresponding the anterior, lateral, and posterior thirds of the deltoid. The results of the present study indicate no difference based on laterality nor position (anterior, lateral, and posterior). Additional cadaver studies with larger samples may provide stronger information regarding the relationship between each position along the course of the axillary nerve. A power analysis to meet .80 power would require an additional seventeen donors (twenty-seven total).

3.2: Introduction

The axillary nerve exits the quadrangular space in the posterior shoulder approximately

5-7 centimeters from the posterolateral acromion (Gurushantappa, Kuppasad, 2015; Tenor et al., 2011; Abhinav et al., 2008). It then travels anteromedially, adjacent to the surgical neck of 41 the humerus on the undersurface of the deltoid in a neurovascular bundle with the posterior circumflex humeral artery (PCHA) (Moore, Agur, 2007). Either within, or just out of the quadrangular space, the AN splits into an anterior and posterior division (Loukas et al., 2009).

The posterior division supplies motor innervation to the posterior deltoid and extends a branch to the teres minor muscle. The anterior division supplies motor innervation to the lateral and anterior deltoid muscle. Both divisions support the afferent innervation to portions of the humeral head, the glenohumeral joint capsule, the rotator cuff, and a portion of the skin overlying the majority of the anterolateral deltoid known as the regimental patch (Loukas et al.,

2009).

Cadaver dissection studies vary in the way the vertical location of the AN is measured making it difficult to compare results from one study to the next. Therefore, the instructions given to surgeons on the relative safe zone for making incisions within the anterior, lateral, and posterior shoulder may not be accurate (Abhinav et al., 2008; Traver et al., 2016; Westphal et al., 2017). The acromion is a common landmark to initiate measurements from. However, even the location on the lateral acromion has been variable; including the anterior angle, the lateral border, and the posterior angle. Given the variability in methods, it is difficult to understand if there is a difference in vertical position of the AN along its course or is the difference strictly a measurement variability. There is limited information on the difference in vertical position of the AN when comparing its exit posteriorly through the quadrangular space and the anterior termination within the deltoid. There may be a different relative safe zone based on the surgical approach chosen, posteriorly versus anteriorly, should the AN travel more proximally as it travels around the humerus. The deltopectoral approach often extends beyond the inferior border of the pectoralis major, exposing the anterior border of the deltoid to surgical trauma as

42 it is split from the pectoralis major (Traver et al., 2016). Typically, blunt separation of the deltoid from the pectoralis major is sufficient to create the deep exposure necessary to get down to the subscapularis and the glenohumeral joint. However, embryologically these tissues may fuse to some extent making a true deltopectoral approach impossible (Soni et al., 2008;

Barberini, 2014). The surgeon may intend to take a deltopectoral approach, but the anatomy dictates the surgeon to perform what may be a true deltoid split approach anteriorly. If the AN travels proximally and near the medial border of the deltoid, then injury to the AN may result.

Therefore, the primary aim of the present study is to compare the vertical position of the axillary nerve along its course from the exit through the quadrangular space to the termination in the anterior deltoid by cadaver dissection by separating into three divisions of the deltoid (anterior, lateral, posterior). The secondary aim is to measure how closely to the medial border the AN terminates within the deltoid as this location may also contribute to unwanted nerve injury during deltoid split or deltopectoral approaches to the shoulder.

3.2.1: Hypothesis

Research Question #1:

Does the AN vary in vertical displacement from typical surgical bony

landmarks along its course between posterior, lateral, and anterior divisions?

Hypothesis 1:

H1: There is a difference between sides of the body for each of the three test

positions (anterior, lateral, posterior divisions)

H0: There is no difference in vertical position between sides of the body at

each of the three test positions (anterior, lateral, posterior divisions)

Hypothesis 2:

H1: There is a difference in vertical position between test positions

H0: There is no difference in vertical position between all six test positions

Research Question #2:

Does the AN terminate nearer than two centimeters from the medial border

of the deltoid increasing the risk of injury during deltopectoral surgical

approaches to the shoulder?

Hypothesis 1:

H1: The AN terminates nearer than two centimeters from the medial border

of the deltoid.

H0: The AN does not terminate within two centimeters of the medial border

of the deltoid.

3.3: Materials and Methods

Ten embalmed cadavers (5 male, 5 female) were available for dissection from the Body

Donor Program at the Ohio State University. Permission was obtained from the Division of

Anatomy in the College of Medicine. The cadavers were initially positioned in supine with the arms along the sides of the thorax. The skin of the anterior and lateral shoulder, along with the arm down to the deltoid tuberosity, was reflected inferiorly according to common dissection technique exposing the entire origin and muscle belly of the anterior and lateral deltoid (Tank,

2009). This was completed bilaterally (Figure 15). The subject was then propped into a modified side-lying position to gain access to the remainder of the skin overlying the posterior deltoid and scapula. Consistent with established dissection protocol, the skin of the posterior 44 shoulder was reflected inferiorly (Figure 16). The anterior and posterior margins of the deltoid were bluntly separated along the fascial separations between the pectoralis major and the teres major, infraspinatus, and triceps, respectively.

Figure 15: Removal of skin overlying the clavicular head of the pectoralis major (black triangle) and anterior deltoid (green triangle) in a left shoulder

Upper Trap

Lower Trap

Sup Posterior Skin Lat Med reflected Inferiorly Inf

Figure 16: Left posterior shoulder (skin reflected inferiorly). Blue Line indicated inferior margin of posterior deltoid.

The origin of the deltoid along the clavicle and scapula was measured with a string and taken to a stationary tape measure for the overall length of the deltoid origin. A straight pin was placed in the clavicle and scapula at the anteromedial and posteromedial terminations, respectively. This overall distance was used to determine the anterior, lateral, and posterior thirds of the deltoid which mark the sites of measurement for the vertical position of the axillary nerve. The string was first folded in half to determine location on the acromion for the center of the lateral third of the deltoid. A straight pin was placed into the acromion at this location. The midpoints of the anterior and posterior thirds of the deltoid were determined next. The overall length of the origin was divided by six in order to locate the center of each third corresponding to the anterior, lateral, and posterior portions of the deltoid. The center of the anterior third is

1/6 the overall length. Therefore, a pin was placed into the clavicle at this location for the

46 proximal end of the measurement. The center of the posterior third of the deltoid is 1/6 the overall distance from the posteromedial termination and a pin similarly placed in this position on the spine of the scapula.

The deltoid was then sharply debrided from its proximal origin entirely, allowing it to be reflected inferiorly exposing the under surface of the deltoid (Figure 17 and 18). The neurovascular bundle was easily identified adhered to the deltoid. The AN was blunted separated from the circumflex artery and vein to confirm identification of the nerve versus the blood vessels. To measure the vertical position of the AN, a string was used at each location and the length was transferred to a stationary tape measure (Figure 19). A knot was tied on one end of the string. A straight pin placed from an outside-in approach (superficial to deep) secured the knot to the AN distally. The deltoid was flipped up to its origin and the string was directed along the fibers towards the pins placed proximally. A hemostat was secured to the string at the location of the pin corresponding to the origin of each third of the deltoid placed along the origin. Distance measurements were taken to the nearest millimeter at all six test positions

(Figure 19).

Figure 17: Posterior Left Shoulder: Posterior deltoid removed from origin and reflected laterally.

Ant Post

Axillary Nerve

Figure 18: Branching Pattern of the Axillary Nerve (deltoid reflected). TM=Teres Minor

Figure 19: Measurement of Vertical Position of Axillary nerve

3.4: Data Analysis

Raw data was entered into IBM SPSS Software (Version 23.0) for analysis. A nested, repeated measures general linear model was performed for determining significance with a P- value set at .05.

3.5: Results

The raw data is presented in Table 2. The descriptive statistics are summarized in Table

3. The average age was 75 (±13) years. The overall length of the deltoid origin was 225 (±16) and 233 (±20) millimeters for the right and left sides, respectively. The nested average vertical distance of the anterior, lateral, and posterior portions of the AN on the right was 58, 61, and 65 millimeters, respectively. In comparison, the average vertical distance of the left AN for the anterior, lateral, and posterior portions was 60, 64, and 65 millimeters, respectively (Figure 20)

Vertical Position of Axillary Nerve From Bony Landmarks 66

54 Anterior Lateral Posterior

Right Left

Figure 20: Comparison of Anterior, Lateral, and Posterior AN position

The range for all positions, regardless of laterality, was 41 to 95 millimeters. There was no significant difference when comparing sides (p=.370) though this had very low power (.135)

(Table 4 between subjects, Table 5 within subjects). There was no significant difference when comparing locations, anterior, lateral, and posterior (p=.171), with a slightly higher power (.327).

The termination of the AN within the anterior deltoid measures 19 (±6) and 20 (±7) millimeters from the anteromedial border of the right and left deltoid, respectively.

Right (mm) Left (mm) Subject- Ant Lat Post Ant Ant Lat Post Ant Sex-Age margin margin 1-M-53 73 85 85 8 75 95 95 10 2-M-89 53 63 76 10 60 57 65 10 3-M-81 46 57 66 22 54 63 78 24 4-F-82 60 50 72 22 55 53 70 24 5-F-59 65 75 59 17 67 72 53 19 6-F-87 53 59 65 21 58 55 62 18 7-M-78 72 70 65 22 67 76 67 23 8-F-60 53 52 60 14 55 60 58 15 9-F-75 60 57 50 27 55 52 55 32 10-M-85 47 41 52 25 50 56 56 22 Table 2: Raw data for cadaver measurements

Descriptive Statistics Std. N Range Minimum Maximum Mean Deviation Variance Std. Statistic Statistic Statistic Statistic Statistic Error Statistic Statistic

Age 10 36 53 89 74.90 4.081 12.905 166.544 DeltoidR 10 49 205 254 225.10 5.036 15.927 253.656 DeltoidL 10 62 215 277 232.90 6.290 19.891 395.656 AntR 10 27 46 73 58.20 3.014 9.531 90.844 AntL 10 25 50 75 59.60 2.441 7.720 59.600 LatR 10 44 41 85 60.90 4.076 12.888 166.100 LatL 10 43 52 95 63.90 4.275 13.519 182.767 PostR 10 35 50 85 65.00 3.376 10.677 114.000 PostL 10 43 52 95 64.90 4.270 13.503 182.322 AntBorderR 10 19 8 27 18.80 2.004 6.339 40.178 AntBorderL 10 22 10 32 19.70 2.155 6.816 46.456 Valid N 10 (listwise) Table 3: Descriptive Statistics Chapter 3. Highlighted measurements less than 5 cm)

Variable Tests Significance Power Laterality .370 .135 Location .171 .327 Location*Laterality .415 .166 Table 4: Between Subjects Variable Results

Variable Tests Significance Power Laterality .370 .135 Location .142 .386 Location*Laterality .541 .140 Table 5: Within Subjects Results

3.6: Discussion

The values for the vertical distance measured from the deltoid origin along the clavicle and scapula are consistent with established data. The averages for each location fall between

58 and 65 millimeters (SD < 5 mm throughout) and there was no statistical difference between sides of the body. However, not all measurements were within the relative safe zone of the axillary nerve (5-7cm) considering the range of measures in this study was 41 to 95 millimeters.

Of the 30 measurements taken across all locations, three were less than five centimeters vertical distance from the bony landmarks chosen (10%). However, these measurements were seen in only two of the ten subjects (20%). Chen and his colleagues described some relative differences with respect to sex and humeral length (Chen et al. 2012; Lui et al., 2011). Generally female subjects have a shorter humerus and potentially an AN that lies nearer the acromion.

This study included both male and female subjects. All measurements taken outside the

52 anatomic safe zone in this study were in female cadavers. The humeral length was not chosen as a variable to use to normalize the data. However, using percentage of humeral length as a relative guide to the location of the axillary nerve has not yet been established.

The anteromedial termination of the AN is less than two centimeters from the medial border of the anterior deltoid in nine of the twenty shoulders measured (45%) and found in at least one shoulder of five of the ten subjects (50%). This is less than the distance measured by

Gurushantappa and Kuppasad (2015). The AN terminated at 3.22 centimeters from the medial border of the deltoid in their study. Given the closer proximity measured in this study (18.8 millimeters), the AN may be more vulnerable to injury during an extended deltoid split approach to the anterior shoulder such as that sued to place intramedullary rods into the humerus. Care must be taken to ensure identification of the leading edge of the deltoid to avoid an unintended deltoid split approach that is started too far laterally.

Given the low power associated with these variables, it is difficult to project these numbers for surgical planning purposes. When applying this information clinically, despite the averages falling within the anatomical safe zone, the surgeon must still actively pursue the vertical position of the axillary nerve given the potential that a high percentage of individuals may have some portion of the axillary nerve that is outside the established safe zone. He or she cannot rely on estimates of the location. It may be helpful for the surgeon to locate the axillary nerve prior to dissection in order to choose an approach that avoids its path. Ultrasound may be useful in determining the location of the axillary nerve prior to making an incision.

3.7: Limitations

Power is significantly limited in the study based on the limited number of cadavers available at the time of data collection. This dissection exposes a significant portion of the shoulder. Therefore, these cadavers are not able to be used for subsequent dissections of the upper extremity or shoulder girdle. Power analysis utilizing these statistics suggest a sample size of twenty-seven (27) to reach a power of at least 0.80 (PS Power and Sample Size Calculations,

Version 3.0, Dupont WD and Plummer, 2009). Intra-rater reliability was not measured in this study. Therefore, measurement could be a source of error. Additional dissections are necessary to build the case for the location of the axillary nerve as it travels around the surgical neck with reference to each third of the deltoid and to establish the intra- and inter-rater reliability of this method.

3.8: Hypotheses and Key Findings

3.8.1: Hypotheses

Research Question #1:

Does the AN vary in vertical displacement from typical surgical bony

landmarks along its course between posterior, lateral, and anterior divisions?

Hypothesis 1 (Table 6):

H1: There is a difference between sides of the body for each of the three test

positions (anterior, lateral, posterior divisions)

H0: There is no difference in vertical position between sides of the body at

each of the three test positions (anterior, lateral, posterior divisions)

Hypothesis 2 (Table 7): 54

H1: There is a difference in vertical position between test positions

H0: There is no difference in vertical position between all six test positions

Research Question #2:

Does the AN terminate nearer than two centimeters from the medial border

of the deltoid increasing the risk of injury during deltopectoral surgical

approaches to the shoulder?

Hypothesis 1 (Table 8):

H1: The AN terminates nearer than two centimeters from the medial border

of the deltoid.

H0: The AN does not terminate within two centimeters of the medial border

of the deltoid.

Laterality H1: There is a difference between sides of H0: There is no the body for each of the three test difference in vertical positions (anterior, lateral, posterior position between sides divisions) of the body at each of the three test positions (anterior, lateral, posterior divisions) Anterior Reject Accept Lateral Reject Accept Posterior Reject Accept Table 6: Hypothesis Outcome for Laterality

Anterior Right H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right N/A N/A Anterior Left Reject Accept Lateral Right Reject Accept Lateral Left Reject Accept Posterior Right Reject Accept Posterior Left Reject Accept

Anterior Left H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right Reject Accept Anterior Left N/A N/A Lateral Right Reject Accept Lateral Left Reject Accept Posterior Right Reject Accept Posterior Left Reject Accept

Lateral Right H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right Reject Accept Anterior Left Reject Accept Lateral Right N/A N/A Lateral Left Reject Accept Posterior Right Reject Accept Posterior Left Reject Accept

Lateral Left H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right Reject Accept Anterior Left Reject Accept Lateral Right Reject Accept Lateral Left N/A N/A Posterior Right Reject Accept Posterior Left Reject Accept Table 7: Hypothesis Outcomes for Location

Posterior Right H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right Reject Accept Anterior Left Reject Accept Lateral Right Reject Accept Lateral Left Reject Accept Posterior Right N/A N/A Posterior Left Reject Accept

Posterior Left H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right Reject Accept Anterior Left Reject Accept Lateral Right Reject Accept Lateral Left Reject Accept Posterior Right Reject Accept Posterior Left N/A N/A Table 7: Hypothesis Outcomes for Location (continued)

< 2cm H1: The AN terminates H0: The AN does not terminate nearer than two centimeters within two centimeters of the from the medial border of medial border of the deltoid. the deltoid. Anterior Border Accept Reject Table 8: Hypothesis Outcome Proximity to Anterior Border of the Deltoid

3.8.2: Key Findings

• The Axillary Nerve terminates less than 2 centimeters from the medial

border of the anterior deltoid.

• There is no difference in vertical position of the AN between sides.

• There is no difference in vertical position of the AN at each of the six test

positions.

Chapter 4: Comparing the Ultrasound location of the Axillary Nerve to Cadaver Dissection: A

Feasibility Study

4.1: Abstract

The axillary nerve is vulnerable to iatrogenic injury during various surgical procedures.

Ultrasound has been valuable for locating peripheral nerves and visualizing the needle tip for placement of peripheral nerve blocks. Ultrasound may be valuable for locating the axillary nerve intraoperatively in order to avoid damage when making incisions or when placing percutaneous screws for fixation of proximal humerus fractures. The location of the axillary nerve in four fresh cadavers (total of seven shoulders) was compared between ultrasound imaging and dissection. The donors were placed prone and the axillary nerve position was located by ultrasound and measured from the acromion directly proximal to this position along the fiber orientation. An incision was made along the location of the soundhead to the deep margin of the deltoid. The axillary nerve was located and measured to the same bony landmark.

The results indicate high correlation (.831) between the measurements establishing the initial criteria for feasibility of ultrasound utilization during certain surgical procedures of the shoulder.

Given the correlation between measurements, the location of the axillary nerve between thirds of the deltoid may be measured via ultrasound to avoid the need for fresh donor cadavers.

Additional studies utilizing ultrasound intraoperatively are necessary to understand the benefits for protecting the axillary nerve or for decreasing operative time dedicated to locating the nerve.

4.2: Introduction

A relative, surgical safe zone has been described in the literature to occupy an area along the lateral circumference of the humerus at the level of the anatomical neck in order to protect the axillary nerve from iatrogenic injury. There has been some disagreement, however, in the vertical displacement of this safe zone ranging from four to eight centimeters from the acromion (Apaydin et al., 2010; Traver et al., 2016; Westphal et al., 2017). Further, the measurements are taken from a number of locations along the lateral acromion including the anterolateral edge, the midpoint of the lateral, and the posterolateral corner making it difficult to compare the vertical position of the axillary nerve along the entire course from exit through the quadrangular space to termination in the anterior deltoid near the deltopectoral groove

(Gurushantappa, Kuppasad, 2015; Apaydin et al., 2010). Therefore, it is imperative that the surgeon take some surgical time to palpate for the AN location or bluntly dissect to visually see the neurovascular bundle within which the AN lies, when working near its location.

The lack of confidence in the anatomic safe zone contributes to the reason some surgeons choose the deltopectoral approach to proximal humerus fractures rather than a mini- open approach with percutaneous screw fixation. The deltopectoral groove approach allows for expanded surgical field visualization of much of the shoulder but is very limited in its exposure to the greater tuberosity and the posterior/superior rotator cuff. This can create difficulties in reducing and fixating greater tuberosity fractures. In contrast, the smaller incisions from the mini-open allows for limited disruption of the deltoid musculature while greatly increasing the visualization and access to the greater tuberosity and infraspinatus. However, the exposure distally is limited by the axillary nerve, which must be located and protected. Additionally, some

59 screws that may be otherwise important for fixation cannot be placed percutaneously due to risk of injury to the axillary nerve.

Once the nerve is located, it is often tagged with suture and retracted out of harm’s way while completing the surgical procedure (Tenor et al., 2011). Iatrogenic injuries have been correlated with tensioning of the nerve from retractors that help to widen the field of view and from bluntly dissecting to find the AN location (Apaydin et al., 2010). In regards to proximal humerus fractures, plate and screw placement, depending on the surgical approach used, have also been shown to cause injury to the AN resulting in loss of power from the deltoid (Traver et al., 2016).

The axillary nerve is also vulnerable in other surgical procedures around the anterior shoulder. There has been a transition in the common fixation of biceps to the proximal humerus when performing a biceps tenodesis. In the past, the long head of the biceps would be trimmed from the superior labrum and pulled out of the rotator interval. The base of the intertubercular

(bicipital) groove would be roughened with a burr to create a bleeding bed. Suture anchors with

2-3 nylon sutures would be placed in the groove and the proximal tendon of the long head of the biceps would be sutured down. The maturation of this procedure and the desire to increase the force to failure has resulted in drilling a hole into the bicipital groove. The proximal tendon would be fixed with an interference screw. More recently, subpectoral, bicortical suture button tunnel fixation has become more utilized because it can more consistently restore the length- tension relationship of the muscle and the possibility for future pathology within the long head of the biceps is eliminated. In addition, the pullout or failure rate may be improved with this fixation (Werner et al., 2015). However, the location of the bicortical tunnel for subpectoral

60 biceps tenodesis places the AN at some risk posteriorly due to its proximity to the humeral cortex (Ding et al., 2014).

Ultrasound (US) has been beneficial in finding and tracking peripheral nerves for placement of nerve blocks (Desroches et al., 2013; Schafhalter-Zoppoth, Gray, 2005). The physician is able to visualize both the nerve and needle tip in real-time to approximate the tip nearest the nerve to bathe with anesthesia. Utilization of US to assist in placement of medication for peripheral nerve blocks, including brachial plexus blocks, may be superior to concurrent electromyography. Real-time US may have additional surgical benefits to visualize peripheral nerves in a similar way.

Ideally, the AN would be visualized prior to dissection to potentially guide the surgeon’s choice of approach (deltopectoral versus deltoid split, etc.). This would provide a more accurate representation of the location of the nerve than to simply assume a safe zone and may allow the surgeon to choose a less invasive path for completion of the surgical intervention. This may require less surgical time and potentially a faster recovery. In addition, US is quick and inexpensive ideally suited for the operating room when time under anesthesia may be a concern. The aim of the current study is to compare the vertical position of the AN measured from a common location between cadaver dissection and ultrasound imaging on fresh cadavers.

This is the first step to justify the feasibility of US as a means to identify the AN for applications within the surgical environment. In addition, this may limit the need for additional cadaver donors when comparing the position of the axillary nerve along its course around the humerus in order to increase the sample size necessary to improve the power.

4.2.1: Hypotheses

Research Question #1:

Can the location of the axillary nerve be identified accurately via ultrasound

imaging?

Hypothesis 1:

H1: There is a difference between the ultrasound-derived location of the AN and

the cadaver dissection on the same subject.

H0: There is no difference between the ultrasound-derived location of the AN

and the cadaver dissection on the same subject.

4.3: Materials and Methods

Four, fresh cadavers were available for dissection from the Ohio State University Donor

Program. A total of seven shoulders (four left, three right) met the inclusion criteria of no prior surgery or injury that would change the anatomy. One right shoulder was excluded due to prior shoulder surgery. Each subject was positioned prone with a block placed under the anterior shoulder to align the scapula into neutral retraction and the arm resting along the trunk in forearm pronation.

4.3.1: US Data Collection

A 6-13MHz, linear ultrasound transducer with a high-definition output (M-Turbo,

Fujifilm SonoSite, Inc. Bothell, WA) was placed along the posterolateral humerus, perpendicular to the contour of the skin surface with the leading edge of the transducer directed cranially. The depth was set to maximize clarity of the image next to the humerus and ranged from 2.7

62 centimeters to 6.0 centimeters. The size of the patient dictated the depth required to optimize visualization of the AN. The US unit was switched to “M mode” to produce a line on the screen that corresponds to the center point of the soundhead and allow for movement to find the axillary nerve (Figure 21).

“M Line” Deltoid

Teres Minor A V

AN Tricep Humeral Surface

Figure 21: US Imaging of the Axillary Nerve. A locates the PCHA and V locates the PCHV. AN shows the axillary nerve located at the M line.

Caudal Cranial

Leading Edge

Figure 22: US measurement of the axillary nerve

The soundhead was gradually moved towards the head of the humerus maintaining perpendicular orientation to the shaft of the humerus until the neurovascular bundle containing the posterior circumflex humeral artery (PCHA), veins and AN were visualized. The location of the neurovascular bundle can be seen within the facial separation of the proximal long head of the triceps, the inferior border of the teres minor both lying deep to the deltoid (Figure 21). The honeycomb appearance of the nerve was confirmed, and the nerve was placed at the level of the image bisecting line. A flexible tape measure was fixed to the skin proximally and distally using straight pins penetrating into the acromion and the humerus, respectively. A measurement was taken at the surface of the skin corresponding to the midpoint of the soundhead to the nearest millimeter, as seen in Figure 22. All US measurements were taken prior to the dissection portion of the study and the author was blinded to this data.

4.3.2: Dissection and data collection

After collection of all US data, a perpendicular incision was made along the side of the flexible tape measure for dissection of the posterolateral shoulder along the same line as the US transducer head which allowed for localization of the AN deep to the deltoid. Sharp dissection with a scalpel carried the incision through the skin and subcutaneous tissue to the deep edge of the deltoid. Next, small, pointed scissors were used to separate the remaining fibers of the deltoid just superficial to the AN. Blunt dissection freed the AN from the PCHA (Figure 23). The distance from the acromion to the AN was measured to the nearest millimeter with the flexible tape measure and recorded (Figure 24).

Inferior Superior

NV Bundle

Figure 23: Neurovascular (NV) bundle containing the axillary nerve and circumflex humeral vessels. (Posterior view of the R shoulder)

Sup Inf

Figure 24: Measurement of the axillary nerve (AN) via dissection (Posterior view of the right shoulder)

4.4: Data Analysis

The dataset was entered into IBM SPSS Statistics (version 23) software for analysis. A paired samples T-test was used to determine differences in the measurements. A paired samples correlation between measurements was also calculated. The level of significance was set at p = 0.05.

4.5: Results

The average age was 75 (± 12 years) and they were all male donors. Height and weight of the donors were not recorded for this study. The data is presented in Table 9, including the descriptive statistics in Table 10. Graphic representation of the data is presented in Figure 25. 66

The ultrasound images can be found in Appendix F. The ultrasound position of the AN was 68 (±

8) millimeters and the dissected vertical distance was 66 (± 8) millimeters from the posterolateral acromion. There is a 0.831 correlation between these paired data points with a p-value of 0.021 (Table 11). The paired samples t-test produced a p-value of 0.444 with no significant difference between modes of identifying the location of the axillary nerve.

Vertical Distance (mm)

Subject 4 L

Subject 3 R

Subject 3 L

Subject 2 R

Subject 2 L

Subject 1 R

Subject 1 L

0 10 20 30 40 50 60 70 80 90

Dissection Ultrasound

Figure 25: Comparison of Ultrasound and Dissection Measurement

Subject Number Age (yrs.) US position (mm) Cadaver position (laterality) (mm) Subject 1 (L) 88 65 58 Subject 1 (R) 55 54 Subject 2 (L) 79 80 72 Subject 2 (R) 72 76 Subject 3 (L) 72 68 70 Subject 3 (R) 63 65 Subject 4 (L) 60 72 70 Table 9: Raw data for US and Cadaver Dissection

Descriptive Statistics Std. N Range Minimum Maximum Mean Deviation Variance Std. Statistic Statistic Statistic Statistic Statistic Error Statistic Statistic Age 4 28.00 60.00 88.00 74.7500 5.90727 11.81454 139.583 USdistance 7 25.00 55.00 80.00 67.8571 3.00340 7.94625 63.143 CadaverDistance 7 22.00 54.00 76.00 66.4286 2.99092 7.91322 62.619 Valid N (listwise) 4 Table 10: Descriptive statistics for axillary nerve position (Chapter 4)

Paired Samples Correlations N Correlation Sig. Pair 1 USdistance & 7 .831 .021 CadaverDistance Table 11: Correlation between dissection and ultrasound measurements of axillary nerve position

4.6: Discussion

The location of the axillary nerve from the lateral acromion is consistent with many other studies and does happen to fall within the established safe zone (Abhinav et al., 2008;

Apaydin et al., 2010). The minimum distance measured in this study was 54 millimeters and the maximum was 80 millimeters. There were no measurements taken outside the safe zone in this study though the AN has been reported to travel as near as three centimeters to the acromion

(Gurushantappa and Kuppasad, 2015; Abhinav et al., 2008). This is the main fear of physicians as most nerves lie within the safe zone, but it is possible the nerve travels elsewhere. The high correlation (0.831) between the US-derived location and the dissection provides confidence to the clinician that US may be utilized within the operating room with accuracy. The null hypothesis for no difference between measurements is accepted. By knowing the location of the AN prior to making incisions, the surgeon may opt to choose an alternative approach, potentially with less risk to the AN and improve overall recovery. Further, the surgeon may be able to place percutaneous locking screws into the locking plate for reduction of proximal humerus fractures while directly visualizing both the nerve and screw tip as seen with ultrasound-guided injections for axillary nerve blocks.

The results of the present study are an indication that further investigation of the utilization of US imaging for real-time localization of peripheral nerves, particularly the AN, is necessary to determine feasibility of US within the surgical environment. This is the first step to advancing use of ultrasound to locate vulnerable structures pre-operatively for planning purposes or intraoperatively for direct visualization. The addition of US may have minimal economic impact to the patient, given the relatively low cost of the modality, but may improve surgical times to allow for additional procedures on a yearly basis. 69

4.7: Limitations

The obvious limitation to the study is the limited sample size. For this portion of the manuscript there were few available cadavers that did not have prior dissection nor prior surgery to the shoulder. The anthropometric data for height and weight was not available for these subjects. Given the contour of the lateral shoulder and arm, the size of the patient may contribute to a difference between measurements. Inter- and intra-rater reliability was not completed for these measurements. There may, in fact, be a learning curve and difference between investigators in regard to locating the bony origin of the deltoid proximally. However, there remains high correlation between the measurements taken by this investigator so the value of US within the surgical setting may continue to be investigated with additional studies specifically utilizing US for this purpose. Finally, these were all male donors. There may be differences in the success of locating the AN between sexes utilizing US.

4.8: Summary and Key Findings

4.8.1: Research Question #1:

Can the location of the axillary nerve be identified accurately via ultrasound

imaging?

Hypothesis 1 (Table 12):

H1: There is a difference between the ultrasound-derived location of the AN and

the cadaver dissection on the same subject.

H0: There is no difference between the ultrasound-derived location of the AN

and the cadaver dissection on the same subject.

Correlation H1: There is a difference H0: There is no difference between the ultrasound- between the ultrasound- derived location of the AN derived location of the AN and the cadaver dissection and the cadaver dissection on the same subject. on the same subject.

US-Cadaver Reject Accept Table 12: Hypothesis Results

4.8.2: Key Findings

• All values for vertical position of the AN fall within the estimated safe

zone.

• There is high correlation between the dissected and ultrasound

measured locations of the axillary nerve confirming the feasibility of

utilizing US for locating peripheral nerves.

Chapter 5: Location of the Axillary Nerve along its course via Ultrasound Imaging

5.1: Abstract

Ultrasonography is a valuable tool for diagnostic evaluation of muscles and tendons, ligaments, and arteries and veins due primarily to its low cost. It has been used to visualize needle penetration for peripheral nerve blocks. The utility within the orthopedic operating room for identifying the location of the axillary nerve has not been established though there is strong correlation between measurements as determined in Chapter 4. The purpose of this study was to identify the location of the axillary nerve within each third of the deltoid muscle utilizing ultrasound imaging. A convenience sample of fifteen volunteers were available for testing. The subjects were seated with the arms in zero abduction and approximately thirty degrees of internal rotation to allow the hands to rest on the thighs in forearm pronation. A 6-

13MHz linear transducer was used to locate the axillary nerve in each of the three test positions.

The average vertical distance from the proximal bony landmark of the axillary nerve was 61, 62, and 64 millimeters for the anterior, lateral, and posterior thirds of the right shoulder respectively. The average vertical distance from the proximal bony landmark of the axillary nerve was 61, 61, and 68 millimeters for the anterior, lateral, and posterior thirds of the left shoulder respectively. There was no difference between right and left sides at any of the three test positions. The posterior location was significantly different from both the anterior and lateral locations. However, the anterior and lateral locations were not statistically different.

The results of the present study suggest some superior migration of the axillary nerve from the exit out of the quadrangular space to its termination in the anterior deltoid measured by ultrasound imaging. 72

5.2: Introduction

The axillary nerve exits the quadrangular space in the posterior shoulder approximately

5-7 centimeters from the acromion (Gurushantappa, Kuppasad, 2015; Tenor et al., 2011;

Abhinav et al., 2008). However, the AN has been located more superiorly at approximately three centimeters from the lateral acromion making it susceptible to injury during deltoid splitting procedures around the shoulder (Gurushantappa and Kuppasad, 2015). A significant portion of the surgical time is devoted to identifying the location of the AN, depending on the approach taken and the skill level of the surgeon, in order to avoid compression, traction, or cutting injuries (Flatow, 1992). This requires palpation and dissection of the nerve once the incision is made. There may be value in knowing the location of the nerve prior to choosing the surgical approach or prior to inserting percutaneous screws for fixation of proximal humerus fractures utilizing ultrasonography.

Three-part proximal humerus fractures are often treated operatively when displacement of the fracture fragments exceeds one centimeter (Figure 26) (Berkes et al., 2013;

Campochiaro et al., 2015). The tuberosities are proximal to the location of the AN so placement of screws for reduction of these fragments does not risk damage to the nerve. The AN is most vulnerable to injury when placing the percutaneous screws to correct the valgus deformity of the humeral shaft as these are located superior and inferior to the surgical neck (Figure 27).

Surgical Neck Fx

Figure 26: X-ray of Left Shoulder Surgical Neck Fracture

Figure 27: Plate and screws of right proximal humerus fracture (Berkes et al., 2013)

Utilization of ultrasound has come a long way from just imaging the growing fetus during pregnancy. Visualizing structures within the abdomen is common within the ER and for

74 diagnosing pathology of the viscera (Whitson, Mayo, 2016). More recently, the value of ultrasound has expanded to orthopedics for real-time imaging of tendons and ligaments for diagnostic purposes to determine the extent of injury (Blankstein, 2011). There are many advantages of using ultrasound within the orthopedic environment when magnetic resonance imaging and computed tomography are the alternatives. Ultrasonography is cost-effective, comfortable, and portable. It can be used on patients with pacemakers and cardiac stents.

Most importantly, as it may relate to use within the operating room, it is quick. However, significant training is required to master the utilization of ultrasound imaging for orthopedic purposes.

The arc of the AN has not been measured with ultrasound. Therefore, the purpose of the present study is to identify the AN using ultrasound imaging and measure the inferior distance from common landmarks associated with the origin of the deltoid. This is one of the first steps for determining the feasibility of US use for planning orthopedic surgeries.

5.2.1 Hypothesis

Research Question #1:

Does the AN vary in vertical displacement from bony landmarks along its

course between posterior, lateral, and anterior divisions via ultrasound

imaging?

Hypothesis 1:

H1: There is a difference between sides of the body for each of the three test

positions (anterior, lateral, posterior divisions)

H0: There is no a difference in vertical position between sides of the body at

each of the three test positions (anterior, lateral, posterior divisions)

Hypothesis 2:

H1: There is a difference in vertical position between test positions

H0: There is no difference in vertical position between all six test positions

5.3: Methods

The study was approved by the Ohio State University Institutional Review Board for human subjects testing. Fifteen subjects (11 males, 4 female) volunteered for the study and satisfied the inclusion criteria including age between 18-50 and no history of shoulder surgery.

The subjects exposed a modest portion of the shoulder to allow access to the clavicle, scapula, and deltoid as shown (Figure 28). The origin of the deltoid was marked along the clavicle and scapula by first having the subject elevate the humerus into 90 degrees of anatomical flexion.

This engaged the anterior deltoid as seen in Figure 28a. The medial border of the deltoid was palpated and marked on the clavicle. The subject then rested the arm at the side. The origin of the anterior and lateral deltoid was palpated and marked along the attachment to the clavicle and acromion, respectively. The subject then elevated the arm to 60 degrees abduction with the elbow bent to 90 degrees in slight humeral internal rotation. Firm pressure was applied to the posterior elbow in an anterior-medial direction while the subject resisted to engage the posterior deltoid (Figure 28b) as described by Kendall and McCreary (2005). The origin of the deltoid was palpated and marked through the postero-medially termination on the spine of the scapula (Figure 29). A flexible tape measure was used to determine the overall length of the deltoid origin on these bony landmarks. This distance was divided in half for the center location 76 corresponding to the lateral third of the deltoid on the lateral border of the acromion. One- sixth of the distance was measured from each end, anteromedial and posteromedial for the location of the anterior and posterior thirds of the deltoid, respectively. These locations were marked as the proximal end of the vertical distance measurements.

Anterior Deltoid Origin

Posterior Deltoid Origin

a b

Figure 28: Identifying the origin of the deltoid. a. Anterior View. b. Posterior View

Med

Ant Post

Lat

Figure 29: Superior View of Left Shoulder Deltoid Origin

A 6-13MHz, linear ultrasound transducer and high-definition ultrasound system (M- turbo Ultrasound System, Fujifilm SonoSite, Inc. Bothell, WA) was used for subjects 1-10. A 5-

10MHz, linear ultrasound transducer and high-definition ultrasound system (M-turbo

Ultrasound System, Fujifilm SonoSite, Inc. Bothell, WA) was used for subjects 11-15. The soundhead was placed along the posterolateral humerus, perpendicular to the contour of the skin surface with the leading edge of the transducer facing cephalad. The depth ranged from 2.7 centimeters to 6.0 centimeters depending on the side of the subject. The US unit was switched to “M mode” to produce a line on the screen that corresponds to the center point of the soundhead and allow for movement of the soundhead to locate the axillary nerve (Figure 30).

“M Line”

Deltoid

Teres Minor

A V

Humeral Surface AN Tricep

Figure 30: Ultrasound Image of the Axillary Nerve. AN: axillary nerve. A: Posterior circumflex humeral artery. V: Posterior circumflex humeral vein

The soundhead was gradually moved towards the head of the humerus maintaining perpendicular orientation until the neurovascular bundle containing the posterior circumflex humeral artery (PCHA) and veins and AN were visualized. The location of the neurovascular bundle can be seen within the facial separation of the proximal long head of the triceps, the inferior border of the teres minor both lying deep to the deltoid (Figure 30). The ultrasound transducer was then positioned along the line connecting the proximal mark for each third and the deltoid insertion. The honeycomb appearance of the nerve was visible, and the nerve was placed at the level of the image bisecting line by moving the transducer superiorly or inferiorly and keeping it perpendicular to the humerus and contour of the shoulder. A flexible tape measure was used to determine the distance from the bony, proximal landmark and the line on the outside of the transducer corresponding the M line bisecting the image. This process was repeated for each location posterior, lateral, and anterior.

5.4: Data Analysis

The data was entered into IBM SPSS Software for data analysis utilizing a nested, repeated measures design with threshold for significance set at p=.05.

5.5: Results

The raw data is displayed in Table 13. Table 14 contains the descriptive statistics. The average age was 32 years (range 20-41). The mean vertical distance from the bony landmarks of the right shoulder was 61 (± 13), 62 (± 9), and 64 (± 11) millimeters for the anterior, lateral, and posterior thirds, respectively. The mean vertical distance from the bony landmarks of the left shoulder was 61 (± 10), 61 (± 10), and 68 (± 12) millimeters for the anterior, lateral, and posterior thirds, respectively.

Right (mm) Left (mm)

Subject Total Ant Lat Post Total Ant Lat Post 1 195 65 72 68 205 60 70 80 2 220 60 60 55 242 58 60 68 3 190 55 55 62 185 48 55 70 4 180 60 65 65 165 55 60 70 5 230 76 65 65 215 65 60 70 6 250 91 80 90 250 80 75 98 7 180 65 65 65 200 55 55 70 8 210 55 60 65 210 60 55 60 9 180 45 55 60 180 50 45 55 10 165 46 45 60 170 52 50 55 11 155 48 48 42 160 52 54 54 12 205 70 68 74 210 76 72 72 13 140 52 61 56 155 60 50 55 14 225 65 72 69 15 210 64 65 71 212 74 74 75 Table 13: Raw Data for Ultrasound.

Descriptive Statistics N Minimum Maximum Mean Std. Deviation Age 15 20.00 41.00 31.6000 7.41427 TotalR 14 140.00 250.00 193.5714 29.89910 TotalL 15 155.00 250.00 198.9333 29.08231 AnteriorR 14 45.00 91.00 60.8571 12.56281 AnteriorL 15 48.00 80.00 60.6667 9.71499 LateralR 14 45.00 80.00 61.7143 9.14354 LateralL 15 45.00 75.00 60.4667 9.78969 PosteriorR 14 42.00 90.00 64.1429 10.77645 PosteriorL 15 54.00 98.00 68.0667 11.62796 Valid N (listwise) 14 Table 14: Descriptive Statistics Chapter 5

There was no difference between right and left sides at any test position (p=.690).

However, there is very low power for this statistic (.067). The posterior location, nearest the quadrangular space, was significantly different to both the anterior and lateral locations (p=.002 and p=.001, respectively). The power for this measure was .918. There is no difference between anterior and lateral locations (p=.953). When including location and laterality, both posterior locations were significantly different than all other locations bilaterally (p=.040). The minimum vertical position of the AN was 45, 48, 45, 45, 42, 54 millimeters for the anterior right and left, the lateral right and left, and the posterior right and left, respectively (Table 14).

5.6: Discussion

The purpose of the study was to compare the vertical position of the axillary nerve at three locations around the humerus. Of the 87 measurements taken across all locations, eight were less than five centimeters from the bony landmarks chosen (9.2%). However, these measurements were taken in only four of the fifteen subjects (26.7%). Chen and his colleagues described some relative differences with respect to sex and humeral length (Chen et al. 2012;

Lui et al. 2011). Generally female subjects have a shorter humerus and potentially an AN that lies nearer the acromion. This study included both male and female subjects. Two subjects each, male and female, included measurements less than five centimeters from the origin so sex was not a determining factor in measurements outside of the anatomic safe zone.

The axillary nerve exits the quadrangular space at 64 millimeters on the right and 68 millimeters on the left as the posterior third measurements. It is significantly different than the lateral (p=.001) and anterior (p=.002) portions suggesting some superior migration of the axillary nerve beginning laterally. Five of the six locations included a measurement outside the safe zone of 5-7 centimeters. The safe zone includes the vast majority of measurements, including the averages for each location. However, there are still some measurements that do not fit within this guideline making the AN vulnerable to intraoperative trauma should deltoid split procedures extend too far inferiorly. This is seen in several of the previous studies on AN position, regardless of the location of the measurement (Cetik et al., 2006; Abhinav et al., 2008;

Apaydin et al., 2010; Gurushantappa, Kappasad, 2015).

When applying this information clinically, despite the averages falling within the anatomical safe zone, the surgeon must still actively pursue the vertical position of the axillary nerve given the potential that a high percentage of individuals may have some portion of the 82 axillary nerve that is outside the established safe zone. He or she cannot rely on estimates of the location. Ultrasound may be a valuable tool to use for locating the AN intraoperatively to directly visualize the nerve. The AN is vulnerable when placing tunnels and buttons for subpectoral biceps tenodesis and the critical locking screw for correcting valgus deformities of proximal humerus fractures.

Given the results of the present study and Chapter 4, ultrasound may be a valuable tool to visualize penetration of these screws while monitoring the position of the AN much like tracing a needle for peripheral nerve blocks. Additional studies are necessary to specifically study the benefits of ultrasonography for placement of pins, screws, and plates during orthopedic surgery. Performing these procedures on cadavers with simulated proximal humerus fractures may build the role of ultrasound within orthopedics.

5.7: Limitations

There was no normalization procedure with regard to humeral length as seen in a prior study (Abhinav, 2008). However, this concept is not fully developed so it is not a reliable measure for protecting the nerve intraoperatively. Inter- and intra-rater reliability was not performed for this study. Therefore, the repeatability of the study results is limited.

5.8: Hypotheses and Key Findings

5.8.1: Hypotheses

Research Question #1:

Does the AN vary in vertical displacement from bony landmarks along its

course between posterior, lateral, and anterior divisions via ultrasound

imaging?

Hypothesis 1 (Table 15):

H1: There is a difference between sides of the body for each of the three test

positions (anterior, lateral, posterior divisions)

H0: There is no a difference in vertical position between sides of the body at

each of the three test positions (anterior, lateral, posterior divisions)

Anterior Reject Accept Lateral Reject Accept Posterior Reject Accept Table 15: Hypothesis Testing for Laterality

Hypothesis 2 (Table 16):

H1: There is a difference in vertical position between test positions

H0: There is no difference in vertical position between all six test positions

Posterior Right H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right Accept Reject Anterior Left Accept Reject Lateral Right Accept Reject Lateral Left Accept Reject Posterior Right Reject Accept Posterior Left N/A N/A

Posterior Left H1: There is a difference in H0: There is no difference in vertical position between vertical position between all six test positions test positions Anterior Right Accept Reject Anterior Left Accept Reject Lateral Right Accept Reject Lateral Left Accept Reject Posterior Right Reject Accept Posterior Left N/A N/A Table 16: Hypothesis testing for location and laterality (continued)

5.8.2: Key Findings

• The AN within the posterior deltoid is located inferiorly compared to

anterior and lateral.

• There is no difference between right and left sides at all test positions.

Chapter 6: Accessory Innervation to the Anterior Deltoid from the Lateral Pectoral Nerve

6.1: Abstract

The lateral pectoral nerve (LPN) has been reported to send a branch through the deltopectoral groove to the anterior deltoid. Two separate case studies show a similar branching pattern of the LPN to the anterior deltoid. There is evidence the LPN provides superficial sensation to an area over the anterior deltoid and anterior acromion, but none have shown motor innervation. Should this nerve cross the deltopectoral groove, it would be likely to be compromised with anterior surgical approaches to the shoulder. The prevalence of this anomaly, however, has not been defined. The purpose of this study was to estimate the frequency of this anatomic variation within a population of embalmed cadavers. Twenty-five embalmed cadavers from the Ohio State University Donor Program were made available for this study. The skin was reflected over the deltopectoral groove and blunt dissection split the deltoid and pectoralis major within the groove. Blunt dissection carried deeply to the subscapularis and conjoined tendons. One branch was identified connecting the lateral pectoral nerve to the anterior deltoid in one of twenty-five cadavers (4%). Given the small sample size, the prevalence of this branching pattern cannot be confidently explained. Additional studies including large samples are necessary to expand the understanding of this accessory innervation. In addition, the components of the nerve should be studied in order to estimate the functional loss post-surgery that may result from transecting the nerve intra-operatively.

6.2: Introduction

The lateral pectoral nerve is named by the origin off the lateral cord and innervates the clavicular and a portion of the sternal pectoralis major muscle. In addition to the motor innervation to the pectoralis major, the lateral pectoral nerve has also been shown to supply sensory information to the skin overlying the distal clavicle, the acromion, and the anterior deltoid (Porzionato et al., 2012). Solomon et al. (1997) reported bilateral branching of the lateral pectoral nerve to the anterior deltoid in a case study of one subject.

Embryologically, the pectoralis major and the anterior deltoid develop from a common pool of myogenic precursor cells that differentiate into the two muscle groups. Occasionally, these muscle groups may not fully separate blurring the septum between these muscles within the deltopectoral groove (Barberini, 2014; Soni et al., 2008). The common embryological origin and common function of these muscles makes it possible they could share innervation.

As described extensively in this manuscript, surgeons are concerned with the axillary nerve location when performing deltopectoral approaches to the shoulder. Given the potential that the LPN extends laterally across the deltopectoral groove, it may be valuable to the surgeon to understand this anatomic variant in order to use caution when making these incisions.

Further, ultrasonographic screening may be able to locate the nerve prior to the procedure.

Despite evidence of this anatomic variant, there are no known studies that measure the frequency or prevalence of this anomaly. The purpose of the present study is to investigate the frequency of lateral pectoral nerve branching into the anterior deltoid muscle as has only been described in case studies to date. Should this variant occur in a substantial portion of the population, the next step would be to determine the amount of contribution to muscle activation the LPN may provide to the deltoid. 88

6.2.1: Hypothesis

Research Question:

Does the lateral pectoral nerve send branches to the anterior deltoid?

Hypothesis 1:

H0: The lateral pectoral nerve does not supply innervation to the anterior

deltoid

H1: The lateral pectoral nerve supplies a branch to the anterior deltoid

6.3: Materials and Methods

Twenty-five embalmed cadavers were available for dissection of right and left anterior shoulder along the deltopectoral groove to investigate the lateral tracking of the lateral pectoral nerve. The subjects were positioned in supine with the arms resting along the lateral trunk. A longitudinal incision was made along the deltopectoral groove from the level of the clavicle down to the superior margin of the axillary fold through the skin and subcutaneous tissue down to the deltoid muscle consistent with the surgical approach to the shoulder (Tenor et al., 2011).

The cephalic vein was identified and bluntly dissected. It was mobilized laterally. Blunt dissection separated the deltoid and pectoralis major muscles and carried down to the conjoint tendon and the anterior surface of the subscapularis muscle. Adipose tissue was grossly removed throughout the dissection to clear the field. The entire length of the deltopectoral groove was visualized to search for any nerves that track laterally to the deltoid (Figure 31).

The deltoid branches of the thoracoacromial artery were identified (Figure 232).

Sup

Lat Med Thoracoacromial A/V

Inf

Sup

Med Lat Cephalic Vein

Inf

Figure 32: Anterior View of Left Shoulder: Deltoid Figure 31: Anterior View of the Right Shoulder with branching of thoracoacromial artery and vein, skin reflected. Yellow line indicates the deltopectoral including cephalic vein groove including the cephalic vein.

6.4: Results

A nerve running horizontally through the deltopectoral groove to the undersurface of the anterior deltoid was identified in one of the twenty-five cadavers (4%). Figure 33 shows the left shoulder with a nerve running laterally through the deltoid pectoral groove. It was in a neurovascular bundle with one of the deltoid branches of the thoracoacromial artery. The nerve was traced back to the lateral pectoral nerve.

M L

Nerve Branch

Figure 33: Anterior view of the left shoulder. LPN branching across deltopectoral groove to the undersurface of the deltoid (yellow arrow). Purple line indicates the medial border of the anterior deltoid.

6.5: Discussion

This is the second known identification of branching from the lateral pectoral nerve to the anterior deltoid. Solomon et al. (1997) in a case study reported bilateral nerves traveling in this manner in one cadaver. In the present study it was only found in the left shoulder of one cadaver. Neither study was able to show whether the nerve carried motor impulses, afferent information, or both. Although there is some evidence the lateral pectoral nerve contributes to some sensation superficially over the distal clavicle and anterior deltoid, the nerve identified in this study entered the underside of the deltoid and may contribute more to motor supply. The importance of this anatomic variant is not yet known as the nerve may only occur in a small percentage of the population. It is not yet known what information this nerve carries, whether 91 motor or sensory. Additionally, if this branching of the lateral pectoral nerve carries motor innervation to the anterior deltoid, it is not known what percentage of the anterior deltoid it supplies. Severing the axillary nerve can create significant electrophysiologic impairment

(Westphal et al., 2017). However, the loss of function or strength associated with severing this nerve is not quantified at this time.

Given the low frequency of presence within a small sample, it is difficult to state confidently that this nerve is present within the population at a frequency that should concern the surgeon.

6.6: Limitations and Conclusion

One out of twenty-five cadavers, one out of fifty shoulders, is hardly enough to consider this an anatomical variation. The chief limitation to this study is the low number of cadavers available for determining the prevalence of accessory innervation. This potential variant should be studied over several years within an anatomy department in order to review hundreds of shoulders. The nerve was traced back to the lateral pectoral nerve. However, the contribution to the nerve was not studied so it may only be a superficial nerve carrying afferent information centrally having little to no effect on shoulder function should it be damaged during open procedures of the anterior shoulder. Additional investigation is necessary to gain further understanding of the components within the nerve once an established frequency is reported with a larger sample.

Chapter 7: Conclusion and Future Direction

The vulnerability of the axillary nerve is without question. Management of this vulnerability takes surgical time and may alter the choices surgeons make when accessing the shoulder for corrective interventions but is necessary to avoid the sequelae associated with accidental transection. The deltopectoral and deltoid splitting approaches are of particular interest with proximal humerus fractures as some fractures may extend inferiorly beyond the surgical neck. Additionally, the tunnel placement and position of the fixation button for subpectoral biceps tenodesis is located in close proximity to the axillary nerve posteriorly.

The preceding study suggests multiple occurrences when the axillary nerve is located less than five centimeters from the bony landmarks typically used to predict the safe zone utilizing both cadaver dissection and ultrasound imaging. Given the frequency of nerves measured outside of the safe zone of the axillary nerve (3/30 in Chapter 3 and 7/87 in Chapter

5), it remains necessary for the surgeon to locate its position on each subject. There is some evidence the axillary nerve may travel proximally as it wraps around the surgical neck of the humerus as seen in both Chapter 3 and 5 of the present study though only significantly so in

Chapter 5. Further, it appears ultrasound may accurately measure the location of the axillary nerve compared to cadaver dissections. It would be valuable to the surgeon to have real-time imaging of the location of the axillary nerve to ensure its safety.

The maturation of this study requires advancing use of ultrasound when performing these procedures. These surgeries should be performed next on cadavers with simulated proximal humerus fractures while utilizing ultrasound imaging to locate the axillary nerve and guide the positioning of percutaneous screws. This will test the value of real-time ultrasound

93 within the surgical setting in relation to proximal humerus fracture fixation. Secondly, ultrasound may be used when performing subpectoral biceps tenodesis on fresh cadaver donors. In addition, the time to complete each surgical procedure may be compared to current norms to estimate the financial benefit of direct visualization of the axillary nerve.

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Appendix A: Consent Form

The Ohio State University Consent to Participate in Research

Study Title: Ultrasound tracking of the axillary nerve and circumflex humeral artery

Principal Investigator: John Bolte, PhD

Co-investigators: Laura Boucher, ATC, PhD and Eric Lenko, PhD candidate

Sponsor: None

• This is a consent form for research participation. It contains important information about this study and what to expect if you decide to participate. Please consider the information carefully. Feel free to discuss the study with your friends and family and to ask questions before making your decision whether or not to participate. • Your participation is voluntary. You may refuse to participate in this study. If you decide to take part in the study, you may leave the study at any time. No matter what decision you make, there will be no penalty to you and you will not lose any of your usual benefits. Your decision will not affect your future relationship with The Ohio State University. If you are a student or employee at Ohio State, your decision will not affect your grades or employment status. • You may or may not benefit as a result of participating in this study. Also, as explained below, your participation may result in unintended or harmful effects for you that may be minor or may be serious depending on the nature of the research. • You will be provided with any new information that develops during the study that may affect your decision whether or not to continue to participate. If you decide to participate, you will be asked to sign this form and will receive a copy of the form. You are being asked to consider participating in this study for the reasons explained below.

1. Why is this study being done? To identify the location of the axillary nerve in the shoulder using ultrasound imaging. An understanding of the location of the axillary nerve is important to know when assessing for injury or when surgical repair of shoulder structures is needed.

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2. How many people will take part in this study? Twenty

3. What will happen if I take part in this study? You will be asked to remove enough clothing to allow ultrasound imaging of the posterior, lateral, and anterior shoulder. Women will be asked to wear a tank top, sports bra, or swimsuit top so that the full deltoid can be accessed. During the data collection you will be asked to first sit comfortably in a standard chair with your arms relaxed on your thighs. The initial measurements will be taken in the seated position. You will then be asked to lie down on your back where measurements will be taken with your arm at your and with your arm out to the side. The ultrasound itself is painless. However, a water-based ultrasound gel will be used as a medium to transmit the sound waves from the transducer to your shoulder. Once the investigator has located the structures for measurement, a felt-tipped pen will mark this location on your skin. A tape measure will be used the document the distance from the acromion at three locations around your shoulder.

4. How long will I be in the study? The enrollment procedures, set-up and testing combined should take no more than one hour.

5. Can I stop being in the study?

You may leave the study at any time. If you decide to stop participating in the study, there will be no penalty to you, and you will not lose any benefits to which you are otherwise entitled. Your decision will not affect your future relationship with The Ohio State University.

6. What risks, side effects or discomforts can I expect from being in the study? There is no expected discomfort from the ultrasound procedure. There is minimal risk of skin irritation from the water-based gel but this is highly unlikely.

7. What benefits can I expect from being in the study? There are no personal benefits to you for participating. However, your participation may enhance the overall understanding of innervation anomalies that may exist.

8. What other choices do I have if I do not take part in the study?

You may choose not to participate without penalty or loss of benefits to which you are otherwise entitled.

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9. Will my study-related information be kept confidential?

Efforts will be made to keep your study-related information confidential. However, there may be circumstances where this information must be released. For example, personal information regarding your participation in this study may be disclosed if required by state law.

Also, your records may be reviewed by the following groups (as applicable to the research): • Office for Human Research Protections or other federal, state, or international regulatory agencies; • U.S. Food and Drug Administration; • The Ohio State University Institutional Review Board or Office of Responsible Research Practices; • The sponsor supporting the study, their agents or study monitors; and • Your insurance company (if charges are billed to insurance).

If this study is related to your medical care, your study-related information may be placed in your permanent hospital, clinic, or physician’s office records. Authorized Ohio State University staff not involved in the study may be aware that you are participating in a research study and have access to your information.

You may also be asked to sign a separate Health Insurance Portability and Accountability Act (HIPAA) research authorization form if the study involves the use of your protected health information.

10. What are the costs of taking part in this study? There are no costs to participate in the study. However, you will be required to pay for your own parking if you need to park on campus to participate.

11. Will I be paid for taking part in this study? No

12. What happens if I am injured because I took part in this study?

If you suffer an injury from participating in this study, you should notify the researcher or study doctor immediately, who will determine if you should obtain medical treatment at The Ohio State University Wexner Medical Center.

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The cost for this treatment will be billed to you or your medical or hospital insurance. The Ohio State University has no funds set aside for the payment of health care expenses for this study.

13. What are my rights if I take part in this study?

If you choose to participate in the study, you may discontinue participation at any time without penalty or loss of benefits. By signing this form, you do not give up any personal legal rights you may have as a participant in this study.

You will be provided with any new information that develops during the course of the research that may affect your decision whether or not to continue participation in the study.

You may refuse to participate in this study without penalty or loss of benefits to which you are otherwise entitled.

An Institutional Review Board responsible for human subjects research at The Ohio State University reviewed this research project and found it to be acceptable, according to applicable state and federal regulations and University policies designed to protect the rights and welfare of participants in research.

14. Who can answer my questions about the study?

For questions, concerns, or complaints about the study you may contact John Bolte, PhD at 614-688-4015.

For questions about your rights as a participant in this study or to discuss other study- related concerns or complaints with someone who is not part of the research team, you may contact Ms. Sandra Meadows in the Office of Responsible Research Practices at 1-800-678-6251.

If you are injured as a result of participating in this study or for questions about a study-related injury, you may contact John Bolte, PhD at 614-688-4015.

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Signing the consent form

I have read (or someone has read to me) this form and I am aware that I am being asked to participate in a research study. I have had the opportunity to ask questions and have had them answered to my satisfaction. I voluntarily agree to participate in this study.

I am not giving up any legal rights by signing this form. I will be given a copy of this form.

Printed name of subject Signature of subject

AM/PM Date and time

Printed name of person authorized to consent for subject Signature of person authorized to consent for subject (when applicable) (when applicable)

AM/PM Relationship to the subject Date and time

Investigator/Research Staff

I have explained the research to the participant or his/her representative before requesting the signature(s) above. There are no blanks in this document. A copy of this form has been given to the participant or his/her representative.

Printed name of person obtaining consent Signature of person obtaining consent

AM/PM Date and time

Witness(es) - May be left blank if not required by the IRB

Printed name of witness Signature of witness

AM/PM Date and time

Printed name of witness Signature of witness

AM/PM Date and time 105

Appendix B: Participant Recruitment Materials

Recruitment Email:

Study Volunteers Requested:

The Division of Anatomy and the School of Health and Rehabilitation Sciences is offering you the opportunity to participate in a research study to determine the location of the axillary nerve

(AN) using ultrasound (US) imaging. There are no costs to participate.

PURPOSE: To identify the location of the AN within the deltoid using US imaging

ELIGIBILITY: Normal BMI without history of metal implants in the shoulder

BENEFITS: No direct benefits to the subjects though an understanding of nerve anomalies may assist surgeons to avoid damaging these nerves during anterior shoulder procedures. Participation is voluntary, and participation or not will have no influence on the individual’s grades or their relationship with any faculty member or study investigators.

COMPENSATION: There is no monetary compensation for volunteers.

CONTACT: The study will take place in the Injury Biomechanics Research Center,

2063 Graves Hall, 333 West 10th Ave.

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John Bolte, PhD. Principle Investigator. 614-688-4015

Eric Lenko, Researcher, PhD Candidate. 631-832-5014

If you would like to participate in the study or have additional questions related to participation, including risks, benefits, and discomforts, you may also reply to this email. A study investigator will contact you.

Recruitment Flyer: Research Participation

Opportunity

As part of the Division of Anatomy within the College of Health and Rehabilitation

Sciences, research subjects are needed to support the advancement of knowledge regarding Ultrasound (US) evaluation of the Brachial Plexus, specifically the Axillary nerve (AN)

PURPOSE: To identify the location of the AN within the deltoid using US imaging 107

ELIGIBILITY: Normal BMI without history of metal implants in the shoulder

BENEFITS: No direct benefits to the subjects though an understanding of nerve anomalies may assist surgeons to avoid damaging these nerves during arthroscopic and open shoulder procedures

COMPENSATION: There is no monetary compensation for volunteers.

CONTACT: The study will take place in the Injury Biomechanics Research Center,

2063 Graves Hall, 333 West 10th Ave.

John Bolte, PhD Or Eric Lenko

Principle Investigator Researcher, PhD Candidate

614-688-4015 614-832-5014

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Appendix C: SPSS Output for Chapter 3 Cadaver Dissection

GET FILE='C:\Users\Eric\Documents\PhD\Cadaver Study\Cadaver Stats\Cadaver 1.sav'. DATASET NAME DataSet1 WINDOW=FRONT. GLM AntR LatR PostR AntL LatL PostL /WSFACTOR=Laterality 2 Polynomial Position 3 Polynomial /MEASURE=Distance /METHOD=SSTYPE(3) /EMMEANS=TABLES(OVERALL) /EMMEANS=TABLES(Laterality) COMPARE ADJ(LSD) /EMMEANS=TABLES(Position) COMPARE ADJ(LSD) /EMMEANS=TABLES(Laterality*Position) /PRINT=DESCRIPTIVE ETASQ OPOWER /CRITERIA=ALPHA(.05) /WSDESIGN=Laterality Position Laterality*Position.

General Linear Model

Notes Output Created 05-JUN-2017 21:32:06 Comments Input Data C:\Users\Eric\Documents\PhD\Cadaver Study\Cadaver Stats\Cadaver 1.sav Active Dataset DataSet1 Filter Weight Split File N of Rows in Working Data 20 File Missing Value Handling Definition of Missing User-defined missing values are treated as missing. Cases Used Statistics are based on all cases with valid data for all variables in the model. 109

Syntax GLM AntR LatR PostR AntL LatL PostL /WSFACTOR=Laterality 2 Polynomial Position 3 Polynomial /MEASURE=Distance /METHOD=SSTYPE(3) /EMMEANS=TABLES(OVERALL) /EMMEANS=TABLES(Laterality) COMPARE ADJ(LSD) /EMMEANS=TABLES(Position) COMPARE ADJ(LSD)

/EMMEANS=TABLES(Laterality*Position) /PRINT=DESCRIPTIVE ETASQ OPOWER /CRITERIA=ALPHA(.05) /WSDESIGN=Laterality Position Laterality*Position. Resources Processor Time 00:00:00.05 Elapsed Time 00:00:00.04

[DataSet1] C:\Users\Eric\Documents\PhD\Cadaver Study\Cadaver Stats\Cadaver 1.sav

Within-Subjects Factors Measure: Distance Dependent Laterality Position Variable 1 1 AntR 2 LatR

3 PostR 2 1 AntL 2 LatL 3 PostL

110

Descriptive Statistics Mean Std. Deviation N AntR 5.8200 .95312 10 LatR 6.0900 1.28880 10 PostR 6.5000 1.06771 10 AntL 5.9600 .77201 10 LatL 6.3900 1.35191 10 PostL 6.4900 1.35027 10

Multivariate Testsa Partial Hypothesis Error Eta Noncent. Observed Effect Value F df df Sig. Squared Parameter Powerc Laterality Pillai's Trace .090 .892b 1.000 9.000 .370 .090 .892 .135 Wilks' .910 .892b 1.000 9.000 .370 .090 .892 .135 Lambda Hotelling's .099 .892b 1.000 9.000 .370 .090 .892 .135 Trace

Roy's Largest .099 .892b 1.000 9.000 .370 .090 .892 .135 Root Position Pillai's Trace .357 2.222b 2.000 8.000 .171 .357 4.444 .327 Wilks' .643 2.222b 2.000 8.000 .171 .357 4.444 .327 Lambda Hotelling's .555 2.222b 2.000 8.000 .171 .357 4.444 .327 Trace Roy's Largest .555 2.222b 2.000 8.000 .171 .357 4.444 .327 Root Laterality * Pillai's Trace .198 .985b 2.000 8.000 .415 .198 1.970 .166 Position Wilks' .802 .985b 2.000 8.000 .415 .198 1.970 .166 Lambda

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Hotelling's .246 .985b 2.000 8.000 .415 .198 1.970 .166 Trace Roy's Largest .246 .985b 2.000 8.000 .415 .198 1.970 .166 Root a. Design: Intercept Within Subjects Design: Laterality + Position + Laterality * Position b. Exact statistic c. Computed using alpha = .05

Mauchly's Test of Sphericitya Measure: Distance Epsilonb Within Subjects Mauchly's Approx. Greenhouse- Huynh- Lower- Effect W Chi-Square df Sig. Geisser Feldt bound Laterality 1.000 .000 0 . 1.000 1.000 1.000 Position .728 2.536 2 .281 .786 .924 .500 Laterality * .800 1.784 2 .410 .833 1.000 .500 Position Tests the null hypothesis that the error covariance matrix of the orthonormalized transformed dependent variables is proportional to an identity matrix. a. Design: Intercept Within Subjects Design: Laterality + Position + Laterality * Position b. May be used to adjust the degrees of freedom for the averaged tests of significance. Corrected tests are displayed in the Tests of Within-Subjects Effects table.

Tests of Within-Subjects Effects Measure: Distance Type III Partial Sum of Mean Eta Noncent. Observe Square Squar Square Paramet d Source s df e F Sig. d er Powera Laterality Sphericity .37 .308 1 .308 .892 .090 .892 .135 Assumed 0 112

Greenhous .37 .308 1.000 .308 .892 .090 .892 .135 e-Geisser 0 Huynh- .37 .308 1.000 .308 .892 .090 .892 .135 Feldt 0 Lower- .37 .308 1.000 .308 .892 .090 .892 .135 bound 0 Error(Laterality) Sphericity 3.110 9 .346 Assumed Greenhous 3.110 9.000 .346 e-Geisser Huynh- 3.110 9.000 .346 Feldt Lower- 3.110 9.000 .346 bound Position Sphericity 2.17 .14 3.690 2 1.845 .195 4.352 .386 Assumed 6 2 Greenhous 2.17 .15 3.690 1.573 2.346 .195 3.422 .336 e-Geisser 6 6 Huynh- 2.17 .14 3.690 1.848 1.997 .195 4.022 .369 Feldt 6 7 Lower- 2.17 .17 3.690 1.000 3.690 .195 2.176 .262 bound 6 4 Error(Position) Sphericity 15.263 18 .848 Assumed Greenhous 14.15 15.263 1.078 e-Geisser 5 Huynh- 16.63 15.263 .918 Feldt 4 Lower- 15.263 9.000 1.696 bound Laterality * Position Sphericity .54 .240 2 .120 .635 .066 1.270 .140 Assumed 1 Greenhous .51 .240 1.667 .144 .635 .066 1.058 .131 e-Geisser 6 Huynh- .54 .240 2.000 .120 .635 .066 1.270 .140 Feldt 1

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Lower- .44 .240 1.000 .240 .635 .066 .635 .110 bound 6 Error(Laterality*Positio Sphericity 3.406 18 .189 n) Assumed Greenhous 15.00 3.406 .227 e-Geisser 1 Huynh- 18.00 3.406 .189 Feldt 0 Lower- 3.406 9.000 .378 bound a. Computed using alpha = .05

Tests of Within-Subjects Contrasts Measure: Distance Type III Sum Partial of Mean Eta Noncent. Observe Lateralit Square d Squar Sig Square Paramet d Source y Position s f e F . d er Powera

Laterality Linear .37 .308 1 .308 .892 .090 .892 .135 0 Error(Laterality) Linear 3.110 9 .346 Position Linear 3.45 .09 3.660 1 3.660 .277 3.454 .383 4 6 Quadrati .83 .030 1 .030 .047 .005 .047 .054 c 3 Error(Position) Linear 9.537 9 1.060 Quadrati 5.726 9 .636 c Laterality * Position Linear Linear .65 .056 1 .056 .214 .023 .214 .070 4 Quadrati 1.58 .24 .184 1 .184 .150 1.585 .204 c 5 0 Linear Linear 2.361 9 .262

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Error(Laterality*Positi Quadrati 1.045 9 .116 on) c a. Computed using alpha = .05

Tests of Between-Subjects Effects Measure: Distance Transformed Variable: Average Type III Sum of Mean Partial Eta Noncent. Observed Source Squares df Square F Sig. Squared Parameter Powera Intercept 2312.604 1 2312.604 417.710 .000 .979 417.710 1.000 Error 49.828 9 5.536 a. Computed using alpha = .05

Estimated Marginal Means

1. Grand Mean Measure: Distance 95% Confidence Interval Mean Std. Error Lower Bound Upper Bound 6.208 .304 5.521 6.895

2. Laterality

Estimates Measure: Distance 115

95% Confidence Interval Laterality Mean Std. Error Lower Bound Upper Bound 1 6.137 .297 5.464 6.809 2 6.280 .328 5.538 7.022

Pairwise Comparisons Measure: Distance 95% Confidence Interval for Mean Differencea (I) Laterality (J) Laterality Difference (I-J) Std. Error Sig.a Lower Bound Upper Bound 1 2 -.143 .152 .370 -.487 .200 2 1 .143 .152 .370 -.200 .487 Based on estimated marginal means a. Adjustment for multiple comparisons: Least Significant Difference (equivalent to no adjustments).

Multivariate Tests Hypothesis Partial Eta Noncent. Observed Value F df Error df Sig. Squared Parameter Powerb

Pillai's trace .090 .892a 1.000 9.000 .370 .090 .892 .135 Wilks' lambda .910 .892a 1.000 9.000 .370 .090 .892 .135 Hotelling's .099 .892a 1.000 9.000 .370 .090 .892 .135 trace Roy's largest .099 .892a 1.000 9.000 .370 .090 .892 .135 root Each F tests the multivariate effect of Laterality. These tests are based on the linearly independent pairwise comparisons among the estimated marginal means. a. Exact statistic b. Computed using alpha = .05

3. Position

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Estimates Measure: Distance 95% Confidence Interval Position Mean Std. Error Lower Bound Upper Bound 1 5.890 .263 5.295 6.485 2 6.240 .402 5.331 7.149 3 6.495 .362 5.677 7.313

Pairwise Comparisons Measure: Distance 95% Confidence Interval for Mean Differencea (I) Position (J) Position Difference (I-J) Std. Error Sig.a Lower Bound Upper Bound 1 2 -.350 .202 .116 -.806 .106 3 -.605 .326 .096 -1.341 .131 2 1 .350 .202 .116 -.106 .806 3 -.255 .328 .457 -.998 .488 3 1 .605 .326 .096 -.131 1.341 2 .255 .328 .457 -.488 .998 Based on estimated marginal means a. Adjustment for multiple comparisons: Least Significant Difference (equivalent to no adjustments).

Multivariate Tests Hypothesis Partial Eta Noncent. Observed Value F df Error df Sig. Squared Parameter Powerb

Pillai's trace .357 2.222a 2.000 8.000 .171 .357 4.444 .327 Wilks' lambda .643 2.222a 2.000 8.000 .171 .357 4.444 .327 Hotelling's .555 2.222a 2.000 8.000 .171 .357 4.444 .327 trace Roy's largest .555 2.222a 2.000 8.000 .171 .357 4.444 .327 root 117

Each F tests the multivariate effect of Position. These tests are based on the linearly independent pairwise comparisons among the estimated marginal means. a. Exact statistic b. Computed using alpha = .05

4. Laterality * Position Measure: Distance 95% Confidence Interval Laterality Position Mean Std. Error Lower Bound Upper Bound

1 1 5.820 .301 5.138 6.502 2 6.090 .408 5.168 7.012 3 6.500 .338 5.736 7.264 2 1 5.960 .244 5.408 6.512 2 6.390 .428 5.423 7.357 3 6.490 .427 5.524 7.456

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Appendix D: SPSS Output for Chapter 4 Correlation

NEW FILE. DATASET NAME DataSet1 WINDOW=FRONT. DESCRIPTIVES VARIABLES=USdistance CadaverDistance /STATISTICS=MEAN STDDEV MIN MAX.

Descriptives

Notes Output Created 06-JAN-2018 15:05:49 Comments Input Active Dataset DataSet1 Filter Weight Split File N of Rows in Working Data 7 File Missing Value Handling Definition of Missing User defined missing values are treated as missing. Cases Used All non-missing data are used. Syntax DESCRIPTIVES VARIABLES=USdistance CadaverDistance /STATISTICS=MEAN STDDEV MIN MAX. Resources Processor Time 00:00:00.00 Elapsed Time 00:00:00.00

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[DataSet1]

Descriptive Statistics N Minimum Maximum Mean Std. Deviation USdistance 7 55.00 80.00 67.8571 7.94625 CadaverDistance 7 54.00 76.00 66.4286 7.91322 Valid N (listwise) 7

T-TEST PAIRS=USdistance WITH CadaverDistance (PAIRED) /CRITERIA=CI(.9500) /MISSING=ANALYSIS.

T-Test

Notes Output Created 06-JAN-2018 15:08:00 Comments Input Active Dataset DataSet1 Filter Weight Split File N of Rows in Working Data 7 File Missing Value Handling Definition of Missing User defined missing values are treated as missing. Cases Used Statistics for each analysis are based on the cases with no missing or out-of-range data for any variable in the analysis.

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Syntax T-TEST PAIRS=USdistance WITH CadaverDistance (PAIRED) /CRITERIA=CI(.9500) /MISSING=ANALYSIS. Resources Processor Time 00:00:00.00 Elapsed Time 00:00:00.00

Paired Samples Statistics Mean N Std. Deviation Std. Error Mean

Pair 1 USdistance 67.8571 7 7.94625 3.00340 CadaverDistance 66.4286 7 7.91322 2.99092

Paired Samples Correlations N Correlation Sig. Pair 1 USdistance & CadaverDistance 7 .831 .021

Paired Samples Test Paired Differences 95% Confidence Interval of the Std. Std. Error Difference Sig. (2- Mean Deviation Mean Lower Upper t df tailed) Pair USdistance - 1.42857 4.61364 1.74379 -2.83834 5.69548 .819 6 .444 1 CadaverDistance

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Appendix E: SPSS Output for Chapter 5 Ultrasound

GLM AnteriorR LateralR PosteriorR AnteriorL LateralL PosteriorL /WSFACTOR=Laterality 2 Polynomial Location 3 Polynomial /MEASURE=Distance /METHOD=SSTYPE(3) /EMMEANS=TABLES(OVERALL) /EMMEANS=TABLES(Laterality) COMPARE ADJ(LSD) /EMMEANS=TABLES(Location) COMPARE ADJ(LSD) /EMMEANS=TABLES(Laterality*Location) /PRINT=DESCRIPTIVE ETASQ OPOWER /CRITERIA=ALPHA(.05) /WSDESIGN=Laterality Location Laterality*Location.

General Linear Model

Notes Output Created 28-FEB-2018 21:26:44 Comments Input Data C:\Users\Eric\Documents\PhD\US Study\US stats\US Data Set.sav Active Dataset DataSet1 Filter Weight Split File N of Rows in Working Data 15 File Missing Value Handling Definition of Missing User-defined missing values are treated as missing. Cases Used Statistics are based on all cases with valid data for all variables in the model.

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Syntax GLM AnteriorR LateralR PosteriorR AnteriorL LateralL PosteriorL /WSFACTOR=Laterality 2 Polynomial Location 3 Polynomial /MEASURE=Distance /METHOD=SSTYPE(3) /EMMEANS=TABLES(OVERALL) /EMMEANS=TABLES(Laterality) COMPARE ADJ(LSD) /EMMEANS=TABLES(Location) COMPARE ADJ(LSD)

/EMMEANS=TABLES(Laterality*Location) /PRINT=DESCRIPTIVE ETASQ OPOWER /CRITERIA=ALPHA(.05) /WSDESIGN=Laterality Location Laterality*Location. Resources Processor Time 00:00:00.11 Elapsed Time 00:00:00.10

Within-Subjects Factors Measure: Distance Dependent Laterality Location Variable 1 1 AnteriorR 2 LateralR 3 PosteriorR 2 1 AnteriorL 2 LateralL

3 PosteriorL

Descriptive Statistics

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Mean Std. Deviation N AnteriorR 60.8571 12.56281 14 LateralR 61.7143 9.14354 14 PosteriorR 64.1429 10.77645 14 AnteriorL 60.3571 10.00467 14 LateralL 59.6429 9.60454 14 PosteriorL 68.0000 12.06393 14

Multivariate Testsa

Partial Hypothesis Error Eta Noncent. Observed Effect Value F df df Sig. Squared Parameter Powerc Laterality Pillai's .013 .166b 1.000 13.000 .690 .013 .166 .067 Trace Wilks' .987 .166b 1.000 13.000 .690 .013 .166 .067 Lambda Hotelling's .013 .166b 1.000 13.000 .690 .013 .166 .067 Trace Roy's Largest .013 .166b 1.000 13.000 .690 .013 .166 .067 Root Location Pillai's .594 8.773b 2.000 12.000 .004 .594 17.546 .918 Trace Wilks' .406 8.773b 2.000 12.000 .004 .594 17.546 .918 Lambda Hotelling's 1.462 8.773b 2.000 12.000 .004 .594 17.546 .918 Trace Roy's Largest 1.462 8.773b 2.000 12.000 .004 .594 17.546 .918 Root Laterality * Pillai's .416 4.281b 2.000 12.000 .040 .416 8.562 .630 Location Trace Wilks' .584 4.281b 2.000 12.000 .040 .416 8.562 .630 Lambda

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Hotelling's .714 4.281b 2.000 12.000 .040 .416 8.562 .630 Trace Roy's Largest .714 4.281b 2.000 12.000 .040 .416 8.562 .630 Root a. Design: Intercept Within Subjects Design: Laterality + Location + Laterality * Location b. Exact statistic c. Computed using alpha = .05

Mauchly's Test of Sphericitya Measure: Distance Epsilonb Within Subjects Mauchly's Approx. Greenhouse- Huynh- Lower- Effect W Chi-Square df Sig. Geisser Feldt bound Laterality 1.000 .000 0 . 1.000 1.000 1.000 Location .946 .666 2 .717 .949 1.000 .500 Laterality * .593 6.276 2 .043 .711 .773 .500 Location Tests the null hypothesis that the error covariance matrix of the orthonormalized transformed dependent variables is proportional to an identity matrix. a. Design: Intercept Within Subjects Design: Laterality + Location + Laterality * Location b. May be used to adjust the degrees of freedom for the averaged tests of significance. Corrected tests are displayed in the Tests of Within-Subjects Effects table.

Tests of Within-Subjects Effects Measure: Distance Type III Sum Partial of Mean Eta Noncent. Observe Square Squar Sig Square Paramet d Source s df e F . d er Powera

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Laterality Sphericity .69 3.857 1 3.857 .166 .013 .166 .067 Assumed 0 Greenhous .69 3.857 1.000 3.857 .166 .013 .166 .067 e-Geisser 0 Huynh- .69 3.857 1.000 3.857 .166 .013 .166 .067 Feldt 0 Lower- .69 3.857 1.000 3.857 .166 .013 .166 .067 bound 0 Error(Laterality) Sphericity 302.14 13 23.242 Assumed 3 Greenhous 302.14 13.00 23.242 e-Geisser 3 0 Huynh- 302.14 13.00 23.242 Feldt 3 0 Lower- 302.14 13.00 23.242 bound 3 0 Location Sphericity 550.16 275.08 11.19 .00 2 .463 22.391 .985 Assumed 7 3 6 0 Greenhous 550.16 289.92 11.19 .00 1.898 .463 21.245 .981 e-Geisser 7 8 6 0 Huynh- 550.16 275.08 11.19 .00 2.000 .463 22.391 .985 Feldt 7 3 6 0 Lower- 550.16 550.16 11.19 .00 1.000 .463 11.196 .871 bound 7 7 6 5 Error(Location) Sphericity 638.83 26 24.571 Assumed 3 Greenhous 638.83 24.66 25.896 e-Geisser 3 9 Huynh- 638.83 26.00 24.571 Feldt 3 0 Lower- 638.83 13.00 49.141 bound 3 0 Laterality * Location Sphericity 132.07 .07 2 66.036 2.838 .179 5.676 .508 Assumed 1 7 Greenhous 132.07 .09 1.421 92.928 2.838 .179 4.034 .419 e-Geisser 1 8

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Huynh- 132.07 .09 1.546 85.445 2.838 .179 4.387 .439 Feldt 1 3 Lower- 132.07 132.07 .11 1.000 2.838 .179 2.838 .345 bound 1 1 6 Error(Laterality*Locati Sphericity 604.92 26 23.266 on) Assumed 9 Greenhous 604.92 18.47 32.741 e-Geisser 9 6 Huynh- 604.92 20.09 30.105 Feldt 9 4 Lower- 604.92 13.00 46.533 bound 9 0

a. Computed using alpha = .05

Tests of Within-Subjects Contrasts Measure: Distance Type III Sum Partial of Mean Eta Noncent. Observ Laterali Locatio Squar Squar Sig Square Paramet ed Source ty n es df e F . d er Powera Laterality Linear .69 3.857 1 3.857 .166 .013 .166 .067 0 Error(Laterality) Linear 302.14 1 23.242 3 3 Location Linear 418.01 418.01 14.08 .00 1 .520 14.088 .934 8 8 8 2 Quadrat 132.14 132.14 .02 1 6.788 .343 6.788 .674 ic 9 9 2 Error(Location) Linear 385.73 1 29.672 2 3 Quadrat 253.10 1 19.469 ic 1 3 Laterality * Location Linear Linear .20 66.446 1 66.446 1.744 .118 1.744 .232 9

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Quadrat .01 65.625 1 65.625 7.782 .374 7.782 .732 ic 5 Error(Laterality*Locati Linear Linear 495.30 1 38.100 on) 4 3 Quadrat 109.62 1 8.433 ic 5 3 a. Computed using alpha = .05

Tests of Between-Subjects Effects Measure: Distance Transformed Variable: Average Type III Sum of Mean Partial Eta Noncent. Observed Source Squares df Square F Sig. Squared Parameter Powera Intercept 327625.190 1 327625.190 568.277 .000 .978 568.277 1.000 Error 7494.810 13 576.524 a. Computed using alpha = .05

Estimated Marginal Means

1. Grand Mean Measure: Distance 95% Confidence Interval Mean Std. Error Lower Bound Upper Bound 62.452 2.620 56.793 68.112

2. Laterality

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Estimates Measure: Distance 95% Confidence Interval Laterality Mean Std. Error Lower Bound Upper Bound 1 62.238 2.729 56.343 68.133 2 62.667 2.614 57.019 68.315

Pairwise Comparisons Measure: Distance 95% Confidence Interval for Mean Differencea (I) Laterality (J) Laterality Difference (I-J) Std. Error Sig.a Lower Bound Upper Bound 1 2 -.429 1.052 .690 -2.701 1.844 2 1 .429 1.052 .690 -1.844 2.701 Based on estimated marginal means a. Adjustment for multiple comparisons: Least Significant Difference (equivalent to no adjustments).

Multivariate Tests Hypothesis Partial Eta Noncent. Observed Value F df Error df Sig. Squared Parameter Powerb Pillai's trace .013 .166a 1.000 13.000 .690 .013 .166 .067 Wilks' lambda .987 .166a 1.000 13.000 .690 .013 .166 .067 Hotelling's .013 .166a 1.000 13.000 .690 .013 .166 .067 trace Roy's largest .013 .166a 1.000 13.000 .690 .013 .166 .067 root

Each F tests the multivariate effect of Laterality. These tests are based on the linearly independent pairwise comparisons among the estimated marginal means. a. Exact statistic b. Computed using alpha = .05

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3. Location

Estimates Measure: Distance 95% Confidence Interval Location Mean Std. Error Lower Bound Upper Bound

1 60.607 2.862 54.425 66.790 2 60.679 2.358 55.584 65.774 3 66.071 2.931 59.739 72.404

Pairwise Comparisons Measure: Distance 95% Confidence Interval for Mean Differenceb (I) Location (J) Location Difference (I-J) Std. Error Sig.b Lower Bound Upper Bound

1 2 -.071 1.189 .953 -2.641 2.498 3 -5.464* 1.456 .002 -8.609 -2.319 2 1 .071 1.189 .953 -2.498 2.641 3 -5.393* 1.316 .001 -8.235 -2.550 3 1 5.464* 1.456 .002 2.319 8.609 2 5.393* 1.316 .001 2.550 8.235 Based on estimated marginal means *. The mean difference is significant at the .05 level. b. Adjustment for multiple comparisons: Least Significant Difference (equivalent to no adjustments).

Multivariate Tests Hypothesis Partial Eta Noncent. Observed Value F df Error df Sig. Squared Parameter Powerb Pillai's trace .594 8.773a 2.000 12.000 .004 .594 17.546 .918 130

Wilks' lambda .406 8.773a 2.000 12.000 .004 .594 17.546 .918 Hotelling's 1.462 8.773a 2.000 12.000 .004 .594 17.546 .918 trace Roy's largest 1.462 8.773a 2.000 12.000 .004 .594 17.546 .918 root Each F tests the multivariate effect of Location. These tests are based on the linearly independent pairwise comparisons among the estimated marginal means. a. Exact statistic b. Computed using alpha = .05

4. Laterality * Location Measure: Distance 95% Confidence Interval Laterality Location Mean Std. Error Lower Bound Upper Bound 1 1 60.857 3.358 53.604 68.111 2 61.714 2.444 56.435 66.994 3 64.143 2.880 57.921 70.365 2 1 60.357 2.674 54.581 66.134 2 59.643 2.567 54.097 65.188

3 68.000 3.224 61.034 74.966

DATASET ACTIVATE DataSet1.

SAVE OUTFILE='C:\Users\Eric\Documents\PhD\US Study\US stats\US Data Set.sav' /COMPRESSED.

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Appendix F: Ultrasound Images and Pictures for Correlation Study

Subject 1-L

Subject 1-R

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Subject 2-L

Subject 2-R

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Subject 3-L

Subject 3-R

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Subject 4-L

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Appendix G: Ultrasound Images for Location of Axillary Nerve

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