Subacromial Impingement Syndrome

Review Article Subacromial Impingement Syndrome

Abstract Alicia K. Harrison, MD Subacromial impingement syndrome (SIS) represents a spectrum Evan L. Flatow, MD of pathology ranging from subacromial bursitis to rotator cuff tendinopathy and full-thickness rotator cuff tears. The relationship between subacromial impingement and rotator cuff disease in the etiology of rotator cuff injury is a matter of debate. Both extrinsic compression and intrinsic degeneration may play a role. Management includes physical therapy, injections, and, for some patients, surgery. There remains a need for high-quality studies of the pathology, etiology, and management of SIS.

ubacromial impingement syn- ment requires a thoughtful and Sdrome (SIS) is a common cause of thorough history and physical exam- shoulder pain.1 Possible etiologies of ination as well as appropriate imag- shoulder pain related to SIS include a ing. spectrum ranging from subacromial bursitis and rotator cuff tendinopathy to partial- and full-thickness ro- History tator cuff tears. Localizing and ad- From the Department of Much of the early literature is diffi- dressing the etiology of shoulder Orthopaedic Surgery, University of cult to interpret in the context of SIS Minnesota Medical School, dysfunction can be challenging due because glenohumeral conditions, es- Minneapolis, MN (Dr. Harrison), and to the interplay of pathology in SIS. the Department of Orthopaedic pecially arthritis and frozen shoulder, Surgery, Mt. Sinai Medical Center, For example, the etiology of rotator were conflated with rotator cuff and New York, NY (Dr. Flatow). cuff disease has long been debated bursal conditions. Duplay2 was likely Dr. Harrison or an immediate family and the cause is likely multifactorial, focusing on glenohumeral disease member serves as a board member, with contributions from external when he described “périarthrite,” owner, officer, or committee member compression, age-related degenera- of the American College of but he also spoke of the role of bur- Surgeons. Dr. Flatow or an tion, trauma, and vascular compro- sal inflammation under the acro- immediate family member serves as mise. Despite controversy regarding mion. Beginning in 1904, Codman3-15 a board member, owner, officer, or the importance of these factors, most wrote a series of articles that drew committee member of the American Shoulder and Elbow Surgeons and investigators believe that external attention to the bursa and the adja- the Arthroscopy Association of North compression from the anterior acro- cent rotator cuff tendons. In hind- America; has received royalties from mion, coracoacromial ligament sight, Codman’s detailed writings Innomed and Zimmer; is a member (CAL), and acromioclavicular joint of a speakers’ bureau or has made can be interpreted in many ways; paid presentations on behalf of and plays a significant role in rotator cuff however, he generally favored a trau- serves as an unpaid consultant to disease by the time treatment is con- matic explanation for supraspinatus Zimmer; and has received research sidered. Secondary causes of im- tears, whereas Meyer16-22 argued for or institutional support from Wyeth. pingement include tuberosity frac- “use attrition,” in which the rotator J Am Acad Orthop Surg 2011;19: ture nonunion or malunion, a mobile cuff tendon and biceps were “ground 701-708 os acromiale, calcific tendinitis, in- between the acromion and the hu- Copyright 2011 by the American stability, and iatrogenic factors. Ac- meral head.” Codman rejected this Academy of Orthopaedic Surgeons. curate diagnosis and effective treat- theory. In his description of supraspi-

November 2011, Vol 19, No 11 701 Subacromial Impingement Syndrome

3 natus tears, Codman noted that of the impingement process. Stage I in- Figure 1 “Dr. Meyer finds similar lesions al- volves acute bursitis with subacromial though he explains them as the result edema and hemorrhage. If extrinsic of attrition,” a mechanism that Cod- compression continues, the bursa no man found “unlikely” except as a longer lubricates the underlying rota- secondary effect. He concluded, tor cuff, leading to tendinopathy of the however, that “one is tempted to rotator cuff tendons, which is classified compromise by saying that many as stage II (Figure 1). In this stage, the causes or combinations of causes anterior fibers of the supraspinatus may produce the same lesion” (ie, may become frayed and may progress rotator cuff tear). to a partial-thickness tear. Stage III is characterized by progression of a partial-thickness tear to a full-thickness Theories tear. Variations in acromial morphology The connection between SIS and ro- were originally described by Bigliani tator cuff disease has been controver- et al31 and classified into three types sial. Some believe that rotator cuff based on acromial shape: type I, flat; disease is due to primary extrinsic type II, curved; and type III, hooked. 23-25 compression; others think that They also noted that a hook-shaped the disease is generally due to intrin- acromion was associated with cuff 26,27 sic tendon degeneration, with degeneration. Since then, others have Coronal T2-weighted magnetic resonance image demonstrating subacromial impingement secondary reported a higher incidence of cuff to cuff weakness and humeral ascent rotator cuff disease and a partial- tears with type III acromial impinge- thickness tear (arrow) in a patient against the overlying structures. ment.32,33 It has been suggested that with subacromial impingement the spurs and excrescences are the re- syndrome. Extrinsic Compression sult of ossification of the CAL inser- The theory of subacromial impinge- tion.30 Chambler et al34 proposed ment has been dominated by debate that this ossification is secondary to anatomic study of CAL morphology regarding the precise location of tensile forces on the ligament and demonstrated that variants with an extrinsic compression source. demonstrated that shoulder abduc- more than one band were associated 37 Watson-Jones28 described impinge- tion places a tensile force on the liga- with rotator cuff degeneration. ment of the lateral acromion on the ment. A recent cadaver study of con- Confusion regarding whether acro- cuff in the midarc of abduction. The tact and forces between the cuff and mial shape is a primary or secondary corrective surgery, lateral or even subacromial arch revealed that sub- factor in cuff disease likely resulted radical (ie, total) acromionectomy, acromial contact and CAL bending from confusing acquired spurs with caused deltoid damage; Neer and occurred in all motions in normal native acromial shape. Nicholson 38 Marberry29 felt that the procedure shoulders.35 The authors suggest that et al helped to reduce this confu- was unnecessary. In his dissection of repetitive contact and bending of the sion in a study of age cohorts of 100 cadaver scapulae, Neer30 identi- CAL may lead to degenerative scapulae from a museum collection. fied spurs and excrescences on the changes, including the proliferative They found that the incidence of undersurface of the anterior acro- acromial spurs. spurs increased with age, whereas mion. He proposed that these Detailed anatomic studies of the overall acromial shape remained un- changes, resulting from impingement CAL have further illustrated aspects changed. of the rotator cuff and humeral head of subacromial space anatomy that against the undersurface of the ante- may play a role in the development Intrinsic Degeneration rior acromion and CAL, were pri- of impingement. In a study of 56 ca- Citing intrinsic characteristics of the marily anterior, not lateral.30 This daver shoulders, Fealy et al36 identi- rotator cuff, some authors assert that finding led Neer to propose the use fied two distinct ligamentous bands: extrinsic compression is not the pri- of anterior acromioplasty to manage an anterolateral and a posteromedial mary cause of rotator cuff disease. this pattern of impingement.24 band. Spurs were commonly found Proposed intrinsic etiologies include Neer30 initially identified three stages in the anterolateral band. Another diminished vascular supply, aging,

702 Journal of the American Academy of Orthopaedic Surgeons Alicia K. Harrison, MD, and Evan L. Flatow, MD and tensile forces leading to rotator acromion. Once this occurs, the phyte formation, acromial entheso- cuff failure. Interestingly, Ogata and changes commonly associated with phytes or sclerosis, and cystic Uhthoff39 found that the incidence SIS are seen: osteophytic spurring of changes of the humeral head are the and severity of cuff tears increased the acromion and tuberosity erosion. more common radiographic findings with age, whereas acromial degener- Supporters of the intrinsic theory related to impingement. However, all ation did not. The authors also iden- cite results in patients with partial- of these findings may be present in tified degenerative changes on the thickness cuff tears treated with asymptomatic subjects, making the acromial undersurface in 31 of 36 débridement without formal acro- relationship of such findings to the (86%) shoulders with articular-sided mioplasty and the frequency of iso- diagnosis of impingement controver- partial cuff tears. They found that lated articular-sided, partial-thick- sial. A recent study found that acro- bursal surface tears were relatively 42 ness tears. Based on results of their miohumeral distance better reflected uncommon, suggesting that cuff ten- study of this management method, the clinical status of patients with dinopathy occurs primarily within Budoff et al42 proposed that “pri- subacromial impingement than did the tendon. mary failure of the rotator cuff most acromial shape.44 It has been hypothesized that the likely occurs by eccentric tension MRI provides detail of potential hypovascular critical zone of the su- overload rather than by impingement sites of subacromial impingment praspinatus tendon is a possible in- from aberrant acromial morphol- through the supraspinatus outlet. trinsic factor, causing tendon degen- ogy.” eration. In a cadaver study, Lohr and Ossification of the CAL or the pres- Uhthoff27 identified a zone of hypo- ence of a subacromial spur can be vascularity within the supraspinatus Diagnosis best identified in the sagittal oblique tendon and specifically noted that no plane; however, differentiation of a vessels were present distally on the Accurate diagnosis of impingement pathologic spur and the normal CAL articular portion of the tendon. They requires a thorough history and can be difficult. MRI also may dem- proposed that such a region of hypo- physical examination as well as ap- onstrate findings of subacromial sub- vascularity is more susceptible to de- propriate imaging. Many patients deltoid bursitis. Findings that indi- generative tendinopathy and rotator with impingement report cuff-related cate this condition include bursal cuff tears. Recently, Benson et al40 re- symptoms such as anterolateral arm thickness >3 mm, the presence of ported evidence of apoptosis and hy- pain, as was reported by Gerber fluid medial to the acromioclavicular 43 poxic damage to the rotator cuff in et al in their study of pain patterns joint, and the presence of fluid in the 45 shoulders with impingement and cuff caused by subacromial space irrita- anterior aspect of the bursa. Typi- tears. However, other studies have tion. Exacerbation of symptoms is cally, MRI is performed with the arm suggested that regions of impaired frequently reported with shoulder el- adducted; however, this position blood supply may be the result, not evation at or above 90° or with lift- does not recreate the position of im- the cause, of tendon injury because ing items away from the body. pingement. injury to the tendon causes ischemia These imaging modalities can be or necrosis through secondary dam- Imaging useful in identifying possible sources age of the vessels.41 Radiographs should be obtained to of mechanical impingement. Diagno- Proponents of the intrinsic theory evaluate for bony abnormality of the sis of SIS is typically determined via do not refute that the acromion plays coracoacromial arch. Routine radio- a combination of physical examina- a role in SIS; rather, they argue that graphs include AP and Grashey tion and radiographic findings. the primary, inciting factor in SIS views (ie, AP radiograph of the stems from weakness and damage to shoulder in the plane of the scapula) Physical Examination the supraspinatus. In the intrinsic as well as outlet and axillary views. Physical examination of the patient theory model, degenerative changes Outlet and axillary views are of par- with shoulder pain must include an or trauma weaken the supraspinatus, ticular importance. The outlet view evaluation of range of motion, rota- and it is then no longer able to center provides visualization of acromial tor cuff strength, and provocative the humeral head on the glenoid. morphology, and the axillary view testing. Previous studies have dem- When the humeral head migrates su- best demonstrates evidence of os ac- onstrated that these tests are com- periorly, the subacromial space nar- romiale, which may lead to second- monly either very specific or very rows, abutting the tuberosity and ary impingement. Acromioclavicular sensitive, which suggests that diag- cuff against the undersurface of the osteoarthritis with inferior osteo- nosis should be determined based on

November 2011, Vol 19, No 11 703 Subacromial Impingement Syndrome all available information, including jection and physical therapy as well ical component of nonsurgical treat- history, physical examination, and as a variety of surgical options, such ment of SIS, subacromial injections imaging studies.46,47 Neer and Haw- as bursectomy alone or subacromial also are frequently used in initial kins tests are typically used to evalu- decompression. In a recent study, treatment of patients presenting with 52 ate for evidence of impingement, and Dorrestijn et al compared surgical symptomatic SIS. In a study of 60 these tests were shown to be highly and nonsurgical treatment in four shoulders with impingement syn- sensitive but not specific.48 randomized controlled trials (RCTs) drome, Kang et al55 reviewed the Further evaluation of the physio- in an effort to determine which treat- accuracy and effectiveness of these logic change that occurs with posi- ment provided better outcomes. injections. The shoulders were ran- tioning during Neer and Hawkins However, the authors could identify domized to receive a subacromial in- no high-quality RCTs that demon- testing has recently been evaluated in jection of corticosteroids, local anes- strated differences in outcome; they vivo with MRI.49 Imaging of shoul- thetic, and contrast dye from one of concluded that, in terms of pain and ders in eight normal volunteers dem- three locations: anterolateral, lateral, shoulder function, no evidence exists onstrated that the Neer and Hawkins or posterior. The authors evaluated for differences in outcome between tests substantially decreased the dis- the accuracy of the injection by ob- nonsurgical and surgical treatment tance from the supraspinatus inser- taining three radiographic views of of SIS. Given the fact that few RCTs tion to the acromion and posterior the shoulder and reported a 70% ac- met the criteria to be included in this glenoid. The Hawkins maneuver curacy rate for each of the portals. review, further high-quality research produced greater subacromial space Although clinical improvement did on the treatment of SIS is needed. narrowing and subacromial rotator not correlate with accuracy in this Nonsurgical management of SIS cuff contact than did the Neer ma- study, an overall improvement in the continues to be successful in most neuver. In a study of 10 subjects with University of California Los Angeles patients.23,53 In a recent prospective normal shoulders (average age, 32 (UCLA) shoulder score and a de- study, Cummins et al53 reported the years), Roberts et al50 found that the crease in the pain score at 3 months results of 100 consecutive patients rotator cuff insertion was closest to were noted. Another study reported with SIS treated with a nonsurgical the anteroinferior acromion at 90° of that the accuracy of blind and treatment protocol consisting of a flexion (ie, Hawkins sign position) ultrasound-guided injections was the subacromial cortisone injection and but not at full elevation (ie, Neer same.56 In a double-blind RCT that physical therapy. In this group, 79% sign position). A cross-sectional compared the effectiveness of sub- of patients did not require surgery analysis of nine cadaver specimens acromial injections of tenoxicam, after two-year follow-up. Of the pa- placed in the Neer and Hawkins po- a nonsteroidal anti-inflammatory tients who did not require surgery, sitions demonstrated similar find- drug, with that of corticosteroid in- the average American Shoulder and ings.51 All shoulders in the Neer posi- jections, the authors found that the Elbow Surgeons outcome score in- tion demonstrated contact between outcomes were not equivalent when creased from 56 to 95, and the aver- the soft tissues and the medial acro- evaluated at time points between 2 age pain score decreased from 4.8 to mion. Shoulders in the Hawkins po- and 6 weeks.57 Improvements in 0.6. The authors did not find evi- sition had contact between soft tis- Constant and Disabilities of the dence of any improvement beyond 1 sues and the CAL. Although these Arm, Shoulder, and Hand scores year. The total number of subacro- studies were done in normal shoul- were significantly greater in the ste- mial steroid/lidocaine injections and ders or cadavers, which may influ- roid group than in the tenoxicam patient response to the initial injec- ence the results, these tests for sub- group at 6 weeks after injection (P < tion were predictors of future surgi- acromial impingement seem to 0.020). cal intervention. Kuhn54 examined demonstrate contact consistent with the role of exercise for the treatment mechanical impingement. of rotator cuff impingement in a sys- Surgical Management tematic review of 11 RCTs. He Nonsurgical Management found that exercise had both statisti- Surgery is indicated in patients with cally and clinically significant effects persistent pain who fail a trial of The most appropriate and beneficial in decreasing pain and improving nonsurgical treatment. Historically, course of treatment for patients with function but did not have such ef- open anterior acromioplasty, as de- SIS is widely debated. Management fects on range of motion or strength. scribed by Neer,30 has been per- options include various types of in- Although physical therapy is a crit- formed in these patients. Neer noted

704 Journal of the American Academy of Orthopaedic Surgeons Alicia K. Harrison, MD, and Evan L. Flatow, MD

Figure 2 throscopic subacromial decompres- Shoulder, and Hand scores and vi- sion. The arthroscopic technique sual analog scale scores 6 months af- permits direct visualization of evi- ter surgery (P < 0.001). dence of arch abrasion and allows Although Neer24 and others who the surgeon to manage possible support the extrinsic compression sources of impingement (Figure 2). A theory recommend a formal acro- meta-analysis of nine studies that mioplasty, review of the literature re- compared open with arthroscopic veals the ongoing controversy re- subacromial decompression reported garding the role of subacromial equivalent surgical times, complica- decompression for SIS. The debate tion rates, and clinical outcomes at a has focused on the necessary compo- minimum 1-year follow-up.59 In ad- nents of subacromial decompression. dition, patients treated with ar- Authors have described subacromial throscopic acromioplasty returned to decompression as bursectomy alone Arthroscopic view of the work sooner and had fewer hospital as well as bursectomy and anterior coracoacromial ligament (CAL) inpatient days than did those who acromioplasty. Much of the debate from a posterior portal. The CAL underwent an open procedure. In a involves whether decompression is has evidence of abrasion and prospective cohort study, Odenbring necessary in the setting of rotator fraying consistent with that seen in 60 63 subacromial impingement. et al reported on 31 shoulders cuff repair. Goldberg et al propose treated with arthroscopic acromio- that acromioplasty is not necessary, plasty and 29 shoulders treated with reporting significant improvement in that “it seems important that the open acromioplasty. They reported Medical Outcomes Study 36-Item rough surface on which the supraspi- excellent or good results in 77% of Short Form comfort and Simple natus is rubbing be removed” and shoulders in the arthroscopic acro- Shoulder Test functions in 27 full- advised removing the undersurface mioplasty cohort, and good results thickness open cuff repairs done of the anterior acromial edge and were maintained 12 to 14 years after without acromioplasty. However, the CAL. In patients with mechanical surgery. Notably, long-term out- authors note that they did make an impingement, the goals of open ante- comes of arthroscopic acromioplasty, effort to “reestablish the normal rior acromioplasty include pain re- which were measured with the smoothness of the undersurface of lief, improvement of surgical expo- UCLA shoulder scoring system, were the coraco-acromial arch,” which sure when cuff repair is necessary, superior to those of open acromio- may reproduce some benefit of acro- and prevention of wear and degener- plasty. mioplasty. ation of the rotator cuff and biceps Other studies have reported good Budoff et al64 reported the long- tendon. Long-term results of this clinical results in patients who under- term results (mean, 9.5 years) of 62 procedure have been good. In a went arthroscopic acromioplasty. In shoulders (60 patients) with partial- study of 32 patients treated with a retrospective study, 162 patients thickness tears treated with débride- open anterior acromioplasty, Chin treated with arthroscopic subacro- ment without acromioplasty. The au- et al58 reported an 88% patient satis- mial decompression without rotator thors reported that 79% of shoulders faction rate, and 23 shoulders (72%) cuff repair were evaluated at a 10- to had excellent or good results based had minimal or no pain at 25-year 13-year follow-up (mean, 11.2 on UCLA shoulder scores and that, follow-up. Five shoulders required years).61 The authors found that iso- of the 60 patients, 77% had no or additional surgery, including distal lated supraspinatus tears did not only minimal pain. Paulos and clavicle excision (one patient), revi- progress clinically, and they con- Franklin65 reported the results of 80 sion anterior acromioplasty (one pa- cluded that subacromial decompres- arthroscopic subacromial decom- tient), and repair of a new rotator sion for subacromial impingement pressions in 76 patients. At an aver- cuff tear (three patients). These find- yields good long-term results. Addi- age follow-up of 32 months, patients ings suggest good long-term results tionally, in a prospective study of 50 had decreased pain with activity and with this procedure and a relatively patients with SIS and persistent at night and showed decreased im- low reoperation rate. symptoms after 6 months of nonsur- pingement signs at final follow-up. With the evolution of arthroscopic gical treatment, Bengtsson et al62 Poorer results were seen in patients shoulder surgery, open anterior acro- found a significant improvement in with full-thickness cuff tears. In a mioplasty has evolved toward ar- median Disabilities of the Arm, prospective randomized study, Garts-

November 2011, Vol 19, No 11 705 Subacromial Impingement Syndrome man and O’Connor66 compared 47 though debate persists regarding the 5. Codman EA: On stiff and painful patients treated with cuff repair and etiology of impingement and rotator shoulders: The anatomy of the subdeltoid or subacromial bursa and its a formal subacromial decompression cuff disease, SIS is likely multifacto- clinical importance. Subdeltoid bursitis. with 46 patients treated with cuff re- rial and may involve both extrinsic Boston Med Surg J 1906;154(22):613- 620. pair alone. All patients had a full- compression and intrinsic degenera- 6. Codman EA: Bursitis subacromialis, or thickness supraspinatus tear and a tive factors. For most patients with periarthritis of the shoulder-joint type II acromion (patients with a SIS, nonsurgical treatment is success- (subdeltoid bursitis). Boston Med Surg J 1908;159(17):533-537. type III acromion were excluded). ful. Surgical intervention is success- The authors found no significant dif- ful in patients who fail nonsurgical 7. Codman EA: Bursitis subacromialis, or periarthritis of the shoulder-joint ference in American Shoulder and El- treatment. Surgeon experience and (subdeltoid bursitis). Boston Med Surg J bow Surgeons scores between the intraoperative assessment may guide 1908;159(18):576-582. groups, even when controlled for the method of surgical treatment. 8. Codman EA: Bursitis subacromialis, or periarthritis of the shoulder-joint tear length. Studies have shown that many surgi- (subdeltoid bursitis). Boston Med Surg J Additional studies have directly cal interventions, including débride- 1908;159(19):615-616. compared various types of decom- ment and open and arthroscopic 9. Codman EA: Bursitis subacromialis, or pression. Henkus et al67 prospec- acromioplasty, have been successful. periarthritis of the shoulder-joint (subdeltoid bursitis). Boston Med Surg J tively evaluated 57 patients with However, there remains a need for 1908;159(22):723-727. primary subacromial impingement high-quality clinical research on the 10. Codman EA: Bursitis subacromialis, or without a rupture of the rotator cuff diagnosis and treatment of SIS. periarthritis of the shoulder-joint who failed nonsurgical management. (subdeltoid bursitis). Boston Med Surg J 1908;159(23):756-759. Patients were randomized to treatment with either bursectomy alone References 11. Codman EA: Complete rupture of the supraspinatus tendon: Operative or bursectomy with acromioplasty. treatment with report of two successful At a mean follow-up of 2.5 years Evidence-based Medicine: Levels of cases. Boston Med Surg J 1911;164(20): 708-710. (range, 1 to 5 years) both bursec- evidence are described in the table of tomy and acromioplasty demon- contents. In this article, references 40, 12. Codman EA: Abduction of the shoulder: An interesting observation in connection strated good clinical results without 47, 56, 57, and 66 are level I studies. with subacromial bursitis and rupture of statistically significant differences be- References 48, 52-55, 58, 60, and 67 the tendon of the supraspinatus. Boston Med Surg J 1912;166(24):890-891. tween the two treatments. However, are level II studies. References 43, 46, there was a trend toward better clini- and 59 are level III studies. References 13. Codman EA: Obscure lesions of the 11, 13, 15, 19, 20, 29, 30, and 61-65 shoulder; Rupture of the supraspinatus cal results with acromioplasty; this tendon. Boston Med Surg J 1927; trend did not reach significance, but are level IV studies. References 1-10, 196(10):381-387. the study was underpowered for this 12, 14, 16-18, 21-28, 31-39, 41, 42, 14. Codman EA, Akerson IB: The pathology finding. The type of acromion and 44, 45, 49-51, and 68-70 are level V associated with rupture of the expert opinion. supraspinatus tendon. Ann Surg 1931; severity of symptoms were found to 93(1):348-359. be more predictive of clinical out- References printed in bold type are 15. Codman EA: Rupture of the come than was the type of treatment. those published within the past 5 supraspinatus: 1834 to 1934. J Bone Even when bone is taken, basic sci- years. Joint Surg Am 1937;19:643-652. ence studies suggest that modest an- 16. Meyer AW: Anatomic specimens of 1. Michener LA, McClure PW, Karduna terior removal is all that is needed to unusual clinical interest. Am J Orthop AR: Anatomical and biomechanical Surg (Phila Pa) 1915;13:86-95. reduce pathologic contact on the ro- mechanisms of subacromial impingement syndrome. Clin Biomech (Bristol, Avon) 17. Meyer AW: Unrecognized occupational tator cuff, and that complete flatten- 2003;18(5):369-379. destruction of the tendon of the long ing of the acromion is rarely head of the biceps brachii. Arch Surg 2. Duplay S: De la peri-arthrite scapulo- 68-70 1921;2:130-144. needed. humerale et de raideurs de l’epaule qui en sont la consequence. Arch Gen Med 18. Meyer AW: Further observations upon 1872;20:513-542. use-destruction in joints. J Bone Joint Surg Am 1922;4:491-511. Summary 3. Codman EA: The Shoulder. New York, NY, G. Miller & Co. Medical Publishers, 19. Meyer AW: Spontaneous dislocation of SIS is one of the most common 1934. the tendon of the long head of the biceps brachii: Report of four cases. Arch Surg causes of shoulder pain and is the 4. Codman EA: Some points on the 1926;13:109-119. diagnosis and treatment of certain subject of ongoing debate in the or- neglected minor surgical lesions. Boston 20. Meyer AW: Spontaneous dislocation and thopaedic surgery community. Al- Med Surg J 1904;150(14):371-374. destruction of tendon of long head of

706 Journal of the American Academy of Orthopaedic Surgeons Alicia K. Harrison, MD, and Evan L. Flatow, MD

biceps brachii: Fifty-nine instances. Arch J Shoulder Elbow Surg 2005;14(5):542- 49. Pappas GP, Blemker SS, Beaulieu CF, Surg 1928;17:493-506. 548. McAdams TR, Whalen ST, Gold GE: In vivo anatomy of the Neer and Hawkins 21. Meyer AW: The minuter anatomy of 37. Kesmezacar H, Akgun I, Ogut T, Gokay sign positions for shoulder impingement. S, Uzun I: The coracoacromial ligament: attritional lesions. J Bone Joint Surg Am J Shoulder Elbow Surg 2006;15(1):40- The morphology and relation to rotator 1931;13:341-360. 49. cuff pathology. J Shoulder Elbow Surg 22. Meyer AW: Chronic functional lesions of 2008;17(1):182-188. 50. Roberts CS, Davila JN, Hushek SG, the shoulder. Arch Surg 1937;35:646- Tillett ED, Corrigan TM: Magnetic 674. 38. Nicholson GP, Goodman DA, Flatow EL, Bigliani LU: The acromion: resonance imaging analysis of the 23. Bigliani LU, Levine WN: Subacromial Morphologic condition and age-related subacromial space in the impingement impingement syndrome. J Bone Joint changes. 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impingement syndrome: A prospective 64. Budoff JE, Rodin D, Ochiai D, Nirschl compared with acromioplasty in the cohort study with a minimum of 12 RP: Arthroscopic rotator cuff management of subacromial impinge- years’ follow-up. Arthroscopy 2008; debridement without decompression for ment syndrome: A prospective 24(10):1092-1098. the treatment of tendinosis. Arthroscopy randomised study. J Bone Joint Surg Br 2005;21(9):1081-1089. 2009;91(4):504-510. 61. Norlin R, Adolfsson L: Small full- thickness tears do well ten to thirteen 65. Paulos LE, Franklin JL: Arthroscopic 68. Bigliani LU, Ticker JB, Flatow EL, years after arthroscopic subacromial shoulder decompression development Soslowsky LJ, Mow VC: The decompression. J Shoulder Elbow Surg and application: A five year experience. relationship of acromial architecture to 2008;17(1 suppl):12S-16S. Am J Sports Med 1990;18(3):235-244. rotator cuff disease. Clin Sports Med 62. Bengtsson M, Lunsjö K, Hermodsson Y, 66. Gartsman GM, O’Connor DP: 1991;10(4):823-838. Nordqvist A, Abu-Zidan FM: High Arthroscopic rotator cuff repair with and 69. Flatow EL, Soslowsky LJ, Ticker JB, patient satisfaction after arthroscopic without arthroscopic subacromial subacromial decompression for shoulder decompression: A prospective, et al: Excursion of the rotator cuff under impingement: A prospective study of 50 randomized study of one-year outcomes. the acromion: Patterns of subacromial patients. Acta Orthop 2006;77(1):138- J Shoulder Elbow Surg 2004;13(4):424- contact. Am J Sports Med 1994;22(6): 142. 426. 779-788. 63. Goldberg BA, Lippitt SB, Matsen FA III: 67. Henkus HE, de Witte PB, Nelissen RG, 70. Colman WW, Kelkar R, Flatow EL, et al: Improvement in comfort and function Brand R, van Arkel ER: Bursectomy The effect of anterior acromioplasty on after cuff repair without acromioplasty. rotator cuff contact: An experimental Clin Orthop Relat Res 2001;390:142- and computer simulation. J Shoulder 150. Elbow Surg 1996;5:S8-S9.

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