2019 IWIW Meeting Abstracts, Las Vegas, Wed. Sept. 4th

SESSION 1: Carpal Ligament

1 Stable Central Column Theory of Carpal Mechanics

Michael Sandow FRACS Wakefield Orthopaedic Clinic Adelaide, Australia

Background:

The carpus is a complicated and functionally challenged mechanical system and advancements in the understanding have been compromised by the recognition that there is no standard carpal mechanical system and no typical wrist. This paper cover component of a larger project that seeks to develop a kinetic model of wrist mechanics to allow reverse analysis of the specific biomechanical controls or rule of a specific patient's carpus, and then use those to create a forward mathematical model to reproduce the unique individual's anatomical motion based on the extracted rules.

Objectives and Methods:

Based on previous observations, the carpus essentially moves with only 2 degrees of freedom - pitch (flexion / extension) and yaw (radial deviation / ulnar deviation), while largely preventing roll (pronation / supination). The object of this paper is therefore to present the background and justification to support the rules based motion (RBM) concept states that the motion of a mechanical system, such as the wrist, is the net interplay of 4 rules - morphology, constraint, interaction and load. The Stable Central Column Theory (SCCT) of wrist mechanics applies the concept of RBM to the carpus, and by using a reverse engineering computational analysis model, identified a consistent pattern of isometric constraints, creating a "Two-Gear Four-Bar" linkage. This study assessed the motion of the carpus using a 3D dynamic visualization model, and the hypothesis was that the pattern and direction of motion of the proximal row, and the distal row with respect the immediately cephalad carpal bones or radius would be very similar in all directions of wrist motion. To identify the unique motion segments, 3D models were created from 5 normal wrists that underwent CT scanning in multiple positions of radial and ulnar deviation as well as flexion and extension. Each carpal row (proximal and distal) was animated with the cephalad carpal bones or radius held immobile. The rotational axis and position of each bone and each row was then compared in sagittal (Flexion-extension) and coronal (radial and ulnar deviation) motion.

Results:

The carpus would appear to have only two degrees of freedom, and yet is stable in those arcs, with the controlling motion loads applied proximally in the forearm. The proximal row moved in a singular arc, but with a varying extent of the unitary arc during sagittal and coronal motion. The isometric constraints were consistent in both directions. The distal row moved on an axis formed by a pivot joint laterally (between the trapezium and scaphoid), and a saddle joint medially (between hamate and triquetrum). This axis changed as the proximal row moved. This created a distinct pattern of row motion to achieve the various required positions of wrist motion. On wrist radial deviation, the scaphoid (with the proximal row) flexed, and the distal row extended, whereas in wrist flexion, the scaphoid flexed (with the proximal row) and so did the distal row. The pattern was reversed in the opposite wrist movements. While the general direction of motion of each row was consistent, the extent was quite variable.

Conclusion:

The project overview and more specific review supports the Stable Central Column Theory of carpal mechanics and the carpus acting as a Two-Gear Four-Bar linkage, as well as the concept of RBM as a means to achieve a quantitative analysis of the normal and injured wrist. This provides a basis for the theory driven quantitative analysis and understanding of the normal and injured wrist. More sophisticated 3 Dimensional modelling will be required to better understand the specifics of carpal motion however the reverse engineering of the specific rules that define each individual wrist can then be applied to a mathematical model to provide a what if test of particular surgical interventions for a proposed injury and this provides one of the first examples of quantitative 3 Dimensional CT analysis, virtual surgical intervention and surgical planning and when the provided surgical solutions are then applied to the model an outcome analysis and expectations as well as prognosis can be defined.

This concept has allowed the theory to be extended to define the deficiencies in the injured wrist, and the solutions to address them.

Ref: https://www.ncbi.nlm.nih.gov/pubmed/?term=Sandow+FRACS+%5BAuthor%5D https://www.ncbi.nlm.nih.gov/pubmed/24072199

https://patentimages.storage.googleapis.com/6b/06/ff/30010d26293bbc/US7236817.pdf

2 Sequential Restraints of Carpal Motion; A 4D CT Analysis Gregory Bain, Melanie Amarasooriya, Neil Kruger, Kim Bryant, Flinders University, Adelaide Australia Introduction The carpus has a complex mechanism of motion which has remained a challenge. 4D CT scan provides new insight into the dynamic motion of the normal and abnormal carpus (1). Methods The authors have assessed the motion of the carpus throughout the range of motion with 4D CT scans. We have developed a tracking systems to allow a greater understanding of the kinematics. Results Assessment of motion analysis of the carpus has demonstrated that throughout carpal motion, there is a reproducible sequential motion of the carpus, which is linked to the sequential restraints. In radial deviation (fig 1)of the wrist, the radial deviators pull the trapezium and trapezoid down onto the scaphoid which leads to ulnar translation of the proximal carpal row. This is then restrained by the volar long radiolunate ligament and the dorsal radiocarpal ligament. The scaphoid then commences to flex over the radioscaphocapitate ligament until restrained by the dorsal scapholunate ligament. The scaphoid then pronates until there is no further motion. In ulnar deviation (fig 2), FCU and ECU pull down the ulnar side of the DCR, which rotates around the capitate. The hamate slides on the triquetrum, extending the triquetrum, and until it screws home. The proximal carpal row then translates radially, and then the STT ligaments extend the scaphoid. Conclusion The sequential motion and restraints of the carpus are important aspects of the normal motion of the carpus. It helps explain why ligaments are at risk during certain motions. It also guides us on how to prevent the scapholunate ligament from being stressed during restricted arcs of motion.

Reference Carr R, MacLean S, Slavotinek J, Bain GI. 4D Computed Tomography Scanning for Dynamic Wrist Disorders: Prospective Analysis and Recommendations for Clinical Utility. Journal of Wrist Surgery. 2019.

3 The Dorsal Lunate Bare Area: Clinical Significance, Identifocation and Management Mark Ross1,2,3, Gregory B Couzens1,4, Scott W Wolfe5

1. Brisbane Hand and Upper Limb Research Institute, Brisbane, Australia 2. Orthopaedic Department, Princess Alexandra Hospital, Brisbane, Australia 3. University of Queensland, Brisbane, Australia 4. Queensland University of Technology, Brisbane, Australia 5. Hospital for Special Surgery, New York, New York

Purpose There is increasing interest in the importance of the dorsal capsular ligaments in stabilising the proximal row of the carpus, in relation to both partial and complete intrinsic ligament injuries.

Materials and Methods The attachment of both the dorsal intercarpal and dorsal radiocarpal ligaments to the dorsal aspect of the lunate was previously assessed in cadaveric dissections. We will discuss the imaging and arthroscopic findings, both in normal anatomy and in patients that have had a disruption of this extrinsic capsular connection to the dorsal lunate.

Results We previously confirmed the consistent and robust capsular connections to the dorsal lunate through cadaveric dissections. We examined MRI and the arthroscopic assessments of these capsular connections in a series of ligamentous injuries of the wrist and have documented both the normal MRI and arthroscopic appearances as well as the abnormal appearances where capsular connections to the dorsal lunate have been disrupted. We propose a technique for arthroscopically assisted mini open reconstruction of the dorsal capsular attachment to the dorsal lunate. We propose that this be termed the RADICL procedure (repair/augmentation of dorsal intercarpal ligament). We will discuss the implications for operative exposure when performing open ligamentous reconstructions around the wrist and the need to consider re-attachment of this capsular disruption as an adjunct to any intrinsic ligament reconstructions.

Conclusions Growing evidence suggests that the extrinsic capsular ligaments may play at least as important, if not, more important role in proximal row stability than the intrinsic ligaments. This warrants a more rigorous assessment of these capsular ligaments and their attachments to the proximal row. We propose that the extrinsic capsular ligaments should no longer be called the secondary stabilisers but rather the extrinsic stabilisers of the proximal row.

4 Anatomy of the Dorsal ScaphoLunoTriquetral Ligament Complex Wessel, L., Kim, D., Ayala-Gamboa, U.A., Ross, M., Couzens, G., Wolfe, S.W.

Introduction Considerable controversy surrounds the anatomy of the dorsal ligament complex of the proximal carpal row. There is little consensus on the precise origin and insertion points of the extrinsic dorsal radiocarpal (DRC) ligament and the intrinsic dorsal intercarpal (DIC) ligaments. Whether or not the DIC and DRC insert on the lunate is debated. The dorsal scaphotriquetral ligament (DST) has been variably described as a labral-like extension of the proximal row over the dorsal capitate, or a component of the dorsal intercarpal ligament. The purpose of our study is to describe the frequency and dimensions of the insertion sites of the DRC, DST and DIC on the lunate, and the anatomic relationship of the DST and DIC ligaments. We hypothesize that the intracapsular DST and DRC ligaments consistently insert on the dorsal lunate, and the DST represents the deep component of the DIC, intimately bound to the dorsal scapholunate and lunotriquetral ligaments.

Methods Fourteen fresh-frozen cadaveric specimens (6 M, 8F), age 70.6 (range 61 to 86) were imaged under fluoroscopy to confirm anatomic posture and alignment of the proximal carpal row. Wrists were excluded is they demonstrated arthritis in the radiocarpal or intercarpal joints, or carpal malalignment, as defined by abnormal radio-lunate and scapholunate angles and scapholunate widening. The DRC and DIC ligaments were visually inspected, photographed and measured in situ. All measurements were made in radial-ulnar direction and proximal distal-direction at the midpoints of the insertion. The conjoined DRC/DIC ligament insertion on the triquetrum was measured and osteotomized tangentially and lifted radially. The insertion sites of the DIC-DST and DRC on the lunate were measured and divided tangentially to expose the dSLIL. Finally, the DIC-DST insertion on the scaphoid ridge and trapezium-trapezoid were measured in a similar fashion. Insertion areas were approximated by multiplying the two distances, assuming a rectangular shape, and then were mapped to anatomic models.

Results The conjoined triquetral insertion of the DIC-DST and DRC measures 89.6  6.2 mm2. In each specimen, the DST represented an inseparable deep subsection of the DIC, and had strong attachments to the lunate 65.0  28.3 mm2, and scaphoid ridge 67.4  26.8 mm2. The DRC consistently inserted on the lunate just proximal to the DIC-DST insertion over a smaller surface area, 29.3±27.6 mm2. The DIC-DST is intimately integrated with the dSLIL, and inserts along the entire dorsal scaphoid ridge 67.4±26.8 mm2, creating a labral-like covering of the dorsal capitate. The DIC consistently inserted on the trapezoid 56.92±27.0 mm2.

Discussion These data demonstrate a consistent insertion of both the DIC and DRC on the lunate, confirming Viegas’ findings. We found the DST to be intimately related to the DIC, and that it constituted a stout deep subsection of the DIC that spanned the entire proximal row with robust insertion sites on each bone. This may be better identified as the “deep DIC” or the “dorsal scapholunotriquetral” ligament (DSLT), and we believe that the DSLT represents the insertion of the DIC on the three bones of the proximal carpal row. The dorsal lunate ligament insertion zone, or “bare area” is an important anatomic landmark, and should be respected in surgical exposures of the wrist. Finally, we disagree with Viegas that the DIC attachment on the trapezoid is variable, finding a consistent extension across the midcarpal joint to the trapezoid, increasing its labral-like enclosure of the capitate.

Figure 1. Anatomic mapping of ligament insertions in comparison to Hagert, 2008.

Figure 2. The DIC-DST is intimately integrated with the dSLIL, creating a labral-like covering of the dorsal capitate.

5 Are All Dorsal Perilunate Injuries Variants Amenable to Arthroscopy? Guillaume Herzberg, Marion Burnier, Lyon, France

Introduction: The use of arthroscopy (ARIF) for dorsal perilunate injuries (PLI) is a recent well-established concept. This concept was recently extended to perilunate injuries non dislocated (PLIND) which are equivalents of PLD-PLFD. Given the wide spectrum of pathology involved in dorsal perilunate dislocations and fracture-dislocations or PLIND injuries, it is unclear whether ARIF can be a useful adjunct for all PLD-PLFD-PLIND variants.The purpose of this study was to retrospectively review our indications for ARIF within a large group of PLI.

Methods Between 2001 and 2019, we managed 269 cases of acute closed unilateral dorsal PLI in our academic single center specialized unit. We began ARIF for PLI in 2004. A total of 123 acute closed unilateral PLI was treated between January 2010 and July 2019. We investigated the number of cases where ARIF was used for PLI between 2010 and 2019. We studied the relationship between the PLI radiological type and the use of ARIF.

Results During the index period, ARIF was used for dorsal PLI in 39/123 cases (32%). ARIF was neither used for polytrauma patients nor for Stage IIB (including Fenton Syndrome) or Stage IIC. We could identify a group 1 (I.D.1) where ARIF was used routinely (depending of arthroscope availability) and a group 2 (I.D.2) where ARIF was not attempted. Group 2 included dorsal PLD-PLFD stage II B (including Fenton Syndrome) and Stage IIC.

Conclusion Our current results suggest that ARIF is not recommended for PLI “I.D.2”, i.e. dorsal PLD-PLFD stage II B (including Fenton Syndrome) and Stage IIC. The use of ARIF is recommended as a routine procedure for PLIND injuries.

6 The capitate sagittal shift. R.Medoff

Purpose: Abnormal angular position of the lunate is often characteristic of carpal instability. The mechanism controlling sagittal rotation of the lunate remains controversial. The purpose of this study was to determine whether capitate sagittal shift is a controlling mechanism of angular rotation of the lunate. Methods: Five normal wrists were studied radiographically in different angles of flexion. Outlines of the radius, scaphoid, lunate, and capitate were outlined and best fit circles applied to the proximal articular surface of the base of the capitate and lunate, and the center of each circle identified. Wrist flexion angle was measured between the longitudinal axis of the capitate and a zero reference line extended from the volar cortex of the radius. Capitate sagittal shift was measured as the shortest distance from the center of the base of the capitate to the zero reference line. Angular alignment of the lunate relative to the angular alignment of the midcarpal axis was also measured. Results: The base of the capitate shifted in a sagittal direction from a palmar to a dorsal position in relation to the zero reference line as the wrist moved from flexion to extension. This translational motion occurred in a predominantly linear fashion showing a high correlation coefficient, although some suggestion of flattening of the displacement curve occurred in positions of extension. For all angular positions of the wrist, however, the lunate angular position maintained nearly perfect alignment with the midcarpal axis. Conclusions: Angular movement of the lunate during flexion and extension of the wrist tracks sagittal shift of the capitate and appears to be an important control mechanism of midcarpal kinematics and stability. Recognition of this component of normal midcarpal kinematics may be a potentially significant element both in the recognition as well as treatment of many carpal instabilities.

7 Wrist traction interferes with the arthroscopic evaluation and surgical repair of the scapholunate misalignment. A kinetic study in cadavers. Mireia Esplugas,MD; Marc Garcia-Elias, MD, PhD; Guillem Salva-Coll, MD, PhD; Alex Lluch- Bergada, MD; Inma Puig-de-la-Bellacasa, MD; Nuria Fernandez, MD; Alfonso Rodriguez- Baeza, MD, PhD. Purposes: The axial loading of a deficient scapholunate ligament (SLL) wrist induces a scaphoid flexion/pronation and the radioscaphoid peak pressure displacing dorsoradially. We designed this study to document the alignment of the scaphoid and the lunate under axial traction to answer two questions: 1) Are there any significant changes in the scapholunate joint alignment between carpal axial loading and carpal axial traction? 2) May carpal axial traction lead to underestimate a scapholunate joint misalignment in a SLL deficient wrist?

Material and Method: We assessed the changes in the alignment of both, the scaphoid and the tandem lunate- triquetrum, with an electromagnetic motion-tracking device. We, first, axially loaded five fresh normal cadaver wrists and, then, axially tractioned them. We subsequently repeated those experiments after a complete scapholunate ligament sectioning. We registered the scaphoid and the tandem lunate- triquetrum 3D alignment results in each condition and compared them using a Wilcoxon signed- rank test. Significance was set at p<0.05.

Results:

Scaphoid (n : 5) Lunate-Triquetrum (n : 5)

SLL intact SLL sectioned SLL intact SLL sectioned Pronation Pronation Pronation Supination

Axial Loading Flexion Flexion Extension Flexion * Dorsoradial Voloulnar Translation Translation Supination Supination Supination Supination Axial Traction Extension Extension Extension Extension * Volar Volar Translation Translation * p< 0.05

Conclusions: 1) There are substantial changes in the scapholunate joint alignment between carpal axial loading and carpal axial traction. 2) Carpal axial traction modifies the scaphoid misalignment typically found in the axially loaded SLL deficient wrists.

Clinical Applications: It is mandatory to completely release the arthroscopic traction: (1) when testing the scapholunate joint gap from the midcarpal joint, (2) when checking the dorsoradial radioscaphoid impingement in the radiocarpal joint.

It is advisable to increase the arthroscopic traction just before tightening and fixing a SLL repair to facilitate the scapholunate joint misalignment reduction.

8 Arthroscopic Staging and Treatment of Stage III Scaphoid Instability with and without Carpal Chondromalacia Houshang Seradge, MD

PURPOSE; We report on the prevalence of associated chondromalacia and other pathologies in patients with dynamic scaphoid instability (DSI) Garcia Elias (GE) stage III and report on the efficacy of arthroscopic treatment for stage III with and without chondromalacia. MATERIALS & METHODS From 191 consecutive wrist arthroscopies, 150 (79%) were diagnosed with DSI. Of the 150 wrists, the average age at time of arthroscopy was 42 years old and the average follow-up was 5.1 years. (range 1-10 years). They were divided into 2 groups. Group A: 53% (79/150) were classified as GE stage III. Group B: 47% (71/150) were classified as GE stage III with additional chondromalacia and other associated intercarpal pathologies (including 52% radial styloid impingement, 23% hamate chondromalacia, 16% triquetrum chondromalacia, 50% TFCC tear, and 11% ulna head chondromalacia). RESULTS Group A: 58% of wrists in this group were treated by arthroscopic debridement alone and did not require further treatment. 42% required dynamic stabilization of the scaphoid (Dynadesis). Group B: 62% of wrists in this group were treated by arthroscopic debridement with concomitant abrasion arthroplasty, partial carpectomy, TFCC excision, and/or radial styloidectomy. Subsequent open surgeries were required in 38% of wrists in this group (67% Dynadesis and/or 33% other indicated stabilization procedures). CONCLUSIONS  Dynamic scaphoid instability of GE stage III can include chondromalacia and other associated wrist pathology. We suggest this group be called stage GE3+.  Arthroscopic treatment alone was successful in more than 50% of the GE 3 and GE 3+ with an average of 5 years follow-up.  Acknowledging the natural history of uncorrected scaphoid instability and the fact that it happens in a younger, active age group, we conclude that medium-term relief can be accomplished by arthroscopic surgery in more than 50% of patients. However, we recommend a longer follow-up for determination of long-term results.

9 Long-term outcomes of delayed scapholunate ligament repair following complete rupture of the ligament: a 9.4-year follow-up

Moheb S Moneim, MD; Camille Aubin-Lemay, MD; Mark S. Anderson, MD; Deana Mercer, MD. Department of Orthopaedics & Rehabilitation, The University of New Mexico, Albuquerque, New Mexico, USA

Purpose: Scapholunate ligament (SLL) injuries are common; however, treatment of isolated tears is challenging owing to difficulty with diagnosis and limited data from other studies. In 1981, the senior author (MSM) described a radiographic view to help directly visualize the scapholunate gap and plan treatment accordingly.1 The purpose of this study was to determine 1) whether delayed repair of only the SLL is an option without other reconstruction procedures and 2) whether functional outcomes are possible despite radiographic presence of arthritis.

Material and Methods: Patients were included who had complete ligament tear at exploration, underwent only SLL repair without capsulodesis or tenodesis, and agreed to return for follow-up (Figure 1). Mean time between injury and surgical treatment was 6 months. Fifteen patients returned for physical and radiographic examinations (11 male; mean age, 48 years). Follow-up measurements included grip strength, range of motion (ROM), disability of the arm, shoulder, and hand (DASH), visual analogue scale (VAS), and radiographic scapholunate gap and angle.

Results: The mean follow-up was 133 months (range, 48-164 months). Mean clinical values versus the uninjured hand were as follows: grip, 38 kg vs 42 kg; extension, 52° vs 57°; flexion, 57° vs 65°; radial deviation, 22° vs 25°; and ulnar deviation, 30° vs 36° (Figure 2). Mean DASH and VAS scores were 5.47 and 1.5, respectively. Preoperatively, the mean scapholunate gap was 2.9 mm and 4.58 mm on posteroanterior (PA) and Moneim views, respectively. Postoperatively, the final mean gap was 2.5 mm and 3.9 mm on the PA and Moneim views, respectively (Figure 3). The mean preoperative and final scapholunate angles were 74 and 72.6 degrees, respectively (Figure 4). Radio scaphoid arthritis was detected intraoperatively in four patients. Seven patients had radiographic arthritis at final follow-up (Figure 5). No patients required additional surgery.

Conclusions: Delayed SLL repair is possible after complete rupture of the ligament. At long-term follow-up, clinical functional outcomes may not correlate with radiographic presence of degenerative arthritis. Reference 1. Moneim MS. The tangential posteroanterior radiograph to demonstrate scapholunate dissociation. J Bone Joint Surg Am. 1981;63(8):1324-1326.

Figure 1. Intraopertaive repair with drill holes in scaphoid.

Figure 2. Mean range of motion (ROM) values at final follow-up on the injured and contralateral wrists. 80 60 40 20 0 EXT EXT FLEX FLEX RD INJ RD UD INJ UD INJ CON INJ CON CON CON ROM

Figure 3. Mean scapholunate gap preoperatively, early postoperatively, and at final follow-up, through the posteroanterior (PA) and Moneim (M) views.

Figure 4. Radiographic scapholunate (SL) angle preoperatively (PRE), early postoperatively (POST), and at final follow-up (FIN).

76 74 72 70 68 66 SL Angle SLA PRE SLA POST SLA FIN Figure 5. Radiographic posteroanterior view and Moneim view. (A) Preoperatively and (B) at final 10-year follow-up, note the presence radio scaphoid arthritis. DASH and VAS scores were both 0 for this patient.

A B

10 Radiotriquetral Ligament Reconstruction with Internal Splint and Capsular Shrinkage for Midcarpal Instability

Randall W. Culp, MD Philadelphia Hand to Shoulder Center, Thomas Jefferson University Department of Orthopaedic Surgery

PURPOSE To report the results of a technique of soft tissue stabilization using capsular shrinkage, palmaris longus graft and internal splint for midcarpal instability.

MATERIALS and METHODS In patient’s symptomatic wrists with midcarpal instability that had failed nonoperative treatment, I used an arthroscopic approach to electrothermally shrink the volar radial and ulnar ligaments and the arcuate ligament. In addition, the radiotriquetral ligament was reconstructed with a palmaris longus graft and internal splinting. 4 consecutive patients were available for follow-up greater than 2 years.

RESULTS There was an overall meaningful improvement of DASH score from 51 preoperative to 27 postoperatively. All patients had mild or no pain. Grip strength increased by 32% while range of motion decreased by 11%. Midcarpal “clunk” test became negative and this was confirmed by fluoroscopy and videotape. All patients returned to their previous occupation or activity. There were no revision surgeries.

CONCLUSION This technique shows good median term results in all 4 patients. Reasonable mobility was maintained despite eliminating the “clunk”. Noteworthy improvements were seen in grip strength and function. I continue to use this promising technique but longer follow-up with larger patient numbers will be required to assess its overall value.

11 Clinical Case: Carpal Ligament Guillaume Herzberg, Marion Burnier, Lyon France

SESSION 2: Distal Radius Fractures

12 Flexor carpi radialis tendon insertion on the trapezial ridge: anatomical description Deana Mercer, MD; Lauren Vernon, MD; Nathan Hoekzema, MD; Robert Gray, MD; Francisco Rubio, MD; Jorge Orbay, MD Introduction: The trapezial ridge is the ulnar portion of the trapezium, which contains a groove in which the flexor carpi radialis (FCR) tendon lies. However, specifics of this insertion are not well described. The purpose of this anatomical dissection was to describe and quantify the zone of insertion of the flexor carpi radialis (FCR) tendon on the trapezial ridge.

Materials & Methods: Fellowship-trained hand surgeons dissected 42 fresh-frozen cadaveric wrists by use of an extended FCR approach through the tendon sheath. The FCR tendon was exposed from the distal third of the forearm across the wrist to the level just proximal to its insertion on the second metacarpal base. The trapezium was exposed with the volar surface clearly visualized. The insertion on the trapezial ridge was quantified using a caliper. Any fiberous attachments to the trapezium were included in the measurement. The measurement was repeated 3 times and then averaged. Results: The zone of insertion was present and apparent in all specimens. In every specimen, the FCR tendon had an insertion on the trapezial ridge. The insertion length was variable (average, 11 mm; range, 3-18 mm).

Conclusions: Mobilizing the FCR is necessary in multiple procedures involving tendon harvest such as tendon transfer, reconstruction, and distal radius metaphysis exposure. The findings of the current study may assist surgeons with surgically exposing and mobilizing the FCR tendon.

13 Flexor carpi radialis tendon insertion on the trapezial ridge: robustness and strength of insertion Deana Mercer, MD; Lauren Vernon, MD; Nathan Hoekzema, MD; Robert Gray, MD; Francisco Rubio, MD; Jorge Orbay, MD

Introduction: The flexor carpi radialis (FCR) tendon is harvested during tendon reconstruction, tendon transfers, and exposure of the distal radius. However, the FCR tendon insertion at the trapezial ridge is not well described. The purpose of this study was to quantify the visual robustness and strength of the FCR tendon insertion.

Materials & Methods: Using 16 fresh-frozen cadaveric wrists, we visually defined the robustness of the FCR tendon insertion as type 1 or 2 based on the fibrous density of the tissue. Type 1 had minimal and translucent fibers, whereas type 2 was more tendinous with obvious Sharpey’s fibers. Afterward, the load to failure of the tendon insertion on the trapezium was measured in the following steps: 1) dissect the FCR tendon through its insertion on the trapezial ridge, 2) pull the tendon in line with the muscle pull using a strain gauge, and 3) load the tendon with the strain gauge looped through a Krakow stitch secured to the proximal end of the tendon. We loaded the tendon at 3 mm/sec until failure, defined as complete rupture of the tendon from the trapezial ridge. For each specimen, robustness was described and strength was quantified.

Results: At the FCR tendon insertion, 12 specimens had very thin translucent tissue, 14 had an area of Sharpey’s fibers and an area of thin translucent tissue, and 16 had a robust insertion with thick Sharpey’s fibers. The load to failure of the FCR tendon insertion on the trapezial ridge varied considerably (average, 43 N; range, 5-130 N).

Conclusions: The current study is clinically relevant owing to the common use of the FCR tendon in surgical reconstruction. When mobilizing the FCR tendon in a zone proximal or distal to the trapezial ridge, the tendon may not mobilize until this area of insertion is released. Understanding the anatomy may be helpful to surgeons when manipulating the FCR tendon.

14 Morphology of the VUC fragment in a cohort of patients receiving CT scans for intra-articular distal radius fracture. Abrams,R.A. Purpose: Intra-articular distal radius fractures have been demonstrated to predictably produce several characteristic fracture fragments. Of these, the volar-ulnar corner (VUC) fragment has presented a particularly difficult clinical challenge. The purpose of our study was to characterize the morphology of the VUC fragment in a consecutive cohort of patients receiving CT scans of the wrist for intra-articular distal radius fracture. Materials and Methods: Between 2010 and 2017, 43 patients with intra-articular distal radius fractures obtained a pre-operative CT scan of the wrist. These images were evaluated to determine: (1) the presence or absence of a VUC fragment, (2) the cross-sectional area of the VUC fragment parallel to the articular surface, and (3) the angle of the articular surface relative to the long axis of the radius in the sagittal plane. Results: Of the 43 CT scans reviewed, 37 (86%) demonstrated the presence of an independent VUC fragment. Of the scans demonstrating a VUC fragment, three major morphologic types were identified: (1) the volar shear type (Fig 1; 21, 48.8%), (2) the dorsally extended type (Fig 2; 9, 20.9%), and (3) the rim avulsion or comminution type (Fig 3; 6, 14.0%). The mean ± stdev surface area and dorsal angulation of the VUC fragment are reported in table 1. Conclusions: To our knowledge this is the first CT based study to focus on description of the pathoanatomic morphology of the VUC fragment in the setting of intra-articular distal radius fracture. We identified 3 major VUC fragment morphologies based on cross-sectional surface area of the fragment and displacement in the sagittal plane on CT. The 3 VUC fragment types identified in this study suggest the need for individualized surgical strategies for each of the different types. Pre-op CT may help the surgeon to best determine the appropriate fixation strategy.

Fig 1- Type 1 Fragment

Fig 2 – Type 2 Fragment

Fig 3 – Type 3 Fragment

Table 1

Dorsal Angulation of Articular Fragment Surface Area (mean ± stdev; Surface Relative to Long Axis Type cm^2) of Radius (mean ± stdev; deg)

1 1.39 ± 0.44 12.19 ± 14.93

2 2.22 ± 0.68 35.46 ± 15.90

3 1.02 ± 0.50 18.52 ± 24.62

15 Threaded Distal Radius Pin and Volar Plate Fixation of Distal Radius Fractures: Early Functional Recovery Michael Kessler, MD MPH, Lucy McCabe BS, John S. Taras, MD

Purpose: To assess the results of threaded distal radius pin (TDRP) fixation when compared to volar plate fixation (VP) of extraarticular distal radius fractures.

Figure 1.

Threaded Distal Radius Pin (T-Pin®) Fixation Volar Plate Fixation

Materials and Methods: A prospective, nonrandomized evaluation of patients undergoing operative fixation of distal radius fracture and postoperative therapy at 1 hand clinic was performed. Clinical variables included implant type, volar tilt, radial height, postoperative wrist flexion, extension, pronation, supination, key pinch and grip strength. The number and duration of therapy visits was recorded. An independent T-test was used to compare 2 groups.

Results: A total of 43 patients were identified (21 TDRP; 22 volar plate). The mean age was 46.3 years for the TDRP group and 53.7 years for the volar plate group, p= 0.170. Preoperative and postoperative radiographic parameters were similar for both groups. Fractures in both groups maintained the reduced position, and no loss of reduction was observed. There were no statistically significant differences for postoperative ROM or pinch or grip strength at the time of discharge from therapy. The mean follow-up duration was 7.4 months. Longer-term follow-up was compromised, because

20% of the volar plate cases required hardware removal. No threaded pins required hardware removal.

The number of postoperative therapy visits was 10.8 for the TDRP and 17.2 for the volar plate group, p=0.034. For TDRP, the mean duration of therapy was 68 days, while for the volar plate it was 132 days, p=0.046.

Figure 2.

Grip Strength and Key Pinch at Therapy Discharge ROM at Therapy Discharge

Conclusions: Both groups achieved equivalent ROM and functional recovery; however, the threaded pin group recovered in significantly less time than the volar plate group.

At the time of discharge from therapy, radiographic and clinical outcomes were similar for both types of implants; but patients treated with TDRD required significantly fewer therapy visits and were discharged an average of 64 days sooner than patients undergoing volar plate fixation.

16 When do we need to repair TFCC in distal radius fractures? Fok MWM, Fang CX, Lau TW, Fung YK, Fung BKK, Leung FKL

Purpose

Distal radius fractures were associated with a high incidence of trianglular fibrocartilage complex (TFCC) tear. However not all patients were noted to have signs and symptoms of TFCC insufficiency We evaluate the status of TFCC after the union of distal radius fractures with plate fixation and the outcome for those who were symptomatic and underwent a delayed repair.

Method and materials:

88 patients with an average age of 52 years old who were elected for the removal of implants after union of distal radius fractures were recruited. Concomitant wrist arthroscopy was performed to assess the status of TFCC. Repair of TFCC was attempted for patients with symptomatic distal radioulnar joint (DRUJ) instability.

Results

There were 17 extra-articular distal radius fractures. 35 patients had ulnar wrist pain and 55 were noted to have DRUJ instability on examinations. The findings of wrist arthroscopies revealed 16 patients with intact TFCC while 69 were noted to have TFCC tears. 13 patients had combined tears. 32 tears were repaired and 37 were not repaired, based on patients’ symptoms and whether the tear was deemed repairable. There was no association between DRUJ or ulnar styloid pain and TFCC tears. However the presence of TFCC tears was significantly associated with clinical features of DRUJ instability (85%V vs 15% p=0.038)

At 6 months post wrist arthroscopy, the average range of wrist movement, power and the DASH score were noted to be improved for all 3 groups i.e. patients with intact TFCC, patients with unrepaired TFCC tear and patients with repaired TFCC, though the improvement of DASH score was only statistically significant for the unrepaired group. There was no difference in the DASH score and power between all groups for pre-arthroscopic period and post-arthroscopic period.

Conclusion

A large majority of TFCC tears remained to be unhealed after the union of distal radius fracture. However, their functional outcome may not differ from those with intact TFCC. For those with symptomatic DRUJ instability, a delayed TFCC repair can improve their outcome.

17 Extraneous DRUJ Subluxation Michael Sandow FRACS Wakefield Orthopaedic Clinic Adelaide

DRUJ instability is typically due to some loss of the intra-articular or extra-articular stabilisers of the distal Radioulnar joint.

A range of causes outside the DRUJ can also cause subluxation or dislocation of the joint, and need to be defined and addressed as repairing or reconstruction only the primary joint stabilisers may fail to correct the joint instability.

These causes included.

1.Ulnar carpal impaction 2. Ulnar capsular tether 3. Ulnar compartment loose body 4. Radial fracture malunion 5. Ulnar styloid impingement 6. Carpal malalignment

Corrective measures have been used to address examples of each of these causes, and will be presented.

18 Ulnar-sided wrist pain and ligament injury in patients with persisting inferior subjective outcome after distal radius fracture. A long-term register study

Magnus Tägil1, Ante Mrkonjic 1,2, Antonio Abramo1,2, Philippe Kopylov1,, Vendela Teurneau1, Mats Geijer3 Marcus Landgren1

1Department of Orthopedics, Clinical Sciences, Lund University and Skåne University Hospital, Lund; 2Department of Hand Surgery Malmö, Skåne University Hospital, Malmö, Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg.

Introduction; The outcome of a distal radius fracture is good, but at one year about 15% still have major disability including pain at rest. The reason is multifactorial. We selected a younger cohort, with inferior subjective outcome at one year from a prospective register, with the specific aim to evaluate the influence of ulnar ligament injuries for long term disability. Methods; Prospective register data from an 8-year period was used, and patients 18-55 years with a DASH score exceeding 35 at 12 months identified. In 2018, 6-13 years after the fracture, the patients were invited for a clinical and radiographic follow-up. Coexisting comorbidity was recorded as well as range of motion, grip strength, ligament laxity, patient-reported outcome (Disabilities of Arm, Shoulder, and Hand, DASH) and pain (VAS). Results; 33 patients, 7 men and 26 women, mean age 47 years at fracture, completed a full clinical and radiographic examination. Six patients had been operated primarily and 11 secondarily. One patient had returned to pre-fracture status with a DASH between 0-10. Ulnar laxity was common and found in 11/33 patients, 5 in the intermediate (DASH 11-35, n=14) and 6 in the poor (DASH >35, n=18) outcome group. Ulnar laxity accompanied by a DRUJ osteoarthritis was found in 6/33 patients and malunion in 10/33. Fifteen patients had coexisting comorbidity and 16 chronic musculoskeletal conditions. Conclusions; - the majority (18/33) remained at a DASH score > 35 - only one patient returned to normal DASH 0-10 - most patients back at work (31/33), half in manual labor! - high incidence of ulnar laxity (6/33), none stabilized surgically - DRUJ osteoarthritis common (14/33) - ulnar laxity combined with DRUJ osteoarthritis more rare (6/33) - coexistent comorbidity common (15/33) - musculoskeletal chronic conditions common (16/33) - mild malunion common (10/33), none exceeding 20 degrees dorsal compression

19 Non-dissociative Carpal Instability Following Intra-articular Distal Radius Fractures Fok MWM, .Fernandez DL and Esplugas M

Purpose

Adaptive carpal instability following mal-united extra-articular Colles’ fracture is a well- recognized condition. Yet carpal instability non-dissociative (CIND) after intra-articular distal radius fractures or radiocarpal dislocation has not been reported.

Method

12 patients with an average age of 32 years old were identified with CIND, 9 after intra- articular fractures and 3 after radiocarpal fracture-dislocations between 2013 and 2018. Ten patients exhibited CIND- palmar radiographically at different post-operative periods, while 2 patients were noted to have CIND-dorsal in initial post-operative x rays.

Results

In cadaveric dissections, CIND-palmar displacement could be reproduced by applying an axial loading and dorsal shearing force on a wrist with sectioned short radiolunate ligament and dorsal radiotriquetral ligament. For the intra-articular fractures with CIND-dorsal displacement the cause is most likely a result of a volar radiocarpal extrinsic ligament injury combined with intra-articular incongruity of the scaphoid fossa.

Eight out of 12 CIND patients suffered from severe wrist pain and underwent subsequent surgeries. Three patients with reducible CIND-palmar had open capsular repair and temporary radiocarpal trans-fixation while 5 patients with fixed non-reducible malalignment were treated with radioscapholunate arthrodesis. At an average follow up of 2.3 years, pain relief was noted, together with an improvement in grip strength and functional range of movement of the wrist. Radiographically the wrist alignment was corrected and maintained in the 8 patients. No surgical complications were observed.

Conclusion

A new CIND entity may present after intra-articular distal radius fractures. Most of the patients were young and were involved in high energy trauma. High index of suspicion is warranted in patients presenting with stiffness during the sub-acute period.

Early detection of the malalignment can preserve the joint mobility by capsular repair. In cases with fixed deformity, a limited radiocarpal fusion maybe beneficial.

20 One third of of patients > 80 years have inferior subjective outcome one year after a distal radius fracture. A register based study.

Magnus Tägil1, Linnea Arvidsson1, Antonio Abramo1,2, Philippe Kopylov1, Marcus Landgren1.

1Department of Orthopedics, Clinical Sciences, Lund University and Skåne University Hospital, Lund; 2Department of Hand Surgery Malmö, Skåne University Hospital, Malmö, Department of Radiology,

Introduction; The subjective outcome after a distal radius fracture is good in the majority of the adult patients, but still one year after the fracture about 15% have major subjective disability, including pain at rest. The reason is multifactorial. In younger patients, the fracture is often due to high energy trauma and associated soft tissue injuries are common. The outcome of a wrist fracture in the elderly is regarded favorable, but data is scarce and evidence absent. We used data from a prospective register evaluating the subjective outcome at 3 and 12 months using a subjective outcome score, the Disabilities of Arm, Shoulder and Hand (DASH).

Methods; Prospective register data from 2005-2012 period was used, and patients > 80 years selected. DASH data was collected from our register and coexisting comorbidity from the medical record.

Results; 563 patients older than 80 years (70 men and 493 women, mean age 86 (80-98) years at fracture) had a fracture during the period. 333/563 patients returned a valid DASH at one year and the median DASH score was 27. One third had a good subjective outcome (DASH 0-10), one-third an intermediate (DASH 11-35) and one-third (DASH > 35) still had substantial problems. 60 patients had been operated. The operated were younger (84 and 85 years, p<0.001) but the DASH scores were similar (32 and 27, p=0.20). None in the operated group had a secondary operation.

Conclusion;

-The subjective outcome one year after distal radius fracture in elderly is not as good as believed.

-The median DASH in superelderly is substantially worse than in the younger.

-Sixty/ 563 patients older than 80 years were operated.

-The subjective outcome was similar in the operated and non-operated group.

- Increased attention may be warranted to improve treatment and subjective outcome in the elderly patients.

21 Clinical Case: Distal Radius Fracture Guillaume Herzberg, Marion Burnier, Lyon France

SESSION 3: Miscellaneous

22 Preliminary Model of the Midcarpal Joint. R Wollstein

Purpose:

A major challenge to deciphering the way structure affects function of the wrist, involves difficulty in obtaining in vivo information. In an attempt to provide a platform for the study of wrist mechanics using in-vivo acquired forces, we built a model of the midcarpal joint based on computed tomography (CT) scans of normal wrists.

Our purpose was to:

1) Provide a preliminary model of the midcarpal joint of the wrist based on CT scans of normal wrists.

2) Compare measurements and evaluation of bone shape within the midcarpal joints based on the model with different methods of measurement based on plain radiographs and CT scans.

Materials and Methods:

Thirty-five CT scans, (dicom files, anonymized, 2mm/slice resolution) were selected from a normal patient database and converted to 3-dimensional .stl files using OsiriX software (version 9, 2016, GNU LGPL), for classification. Solid Mechanics study in stationary conditions was used through the COMSOL library. Material properties for these models were generated from COMSOL materials library (table 1). Simulated loads were applied in the most distal articular surface of the model. A load of 200N was applied in a distal to proximal direction, consistent with other studies.

Results:

The midcarpal joint measurements estimated from the model did not differ significantly from measurements as assessed on plain radiographs and CT scans.

There is a 33% of individuals showing a Type 1 joint, and a 67% of individuals in the sample with a Type 2 joint.

The movements or displacement of the components in the midcarpal joint differed between wrist types 1 and 2.

The angle between the lunate and the capitate was significantly different between lunates type 1 and 2.

Conclusions:

The proposed model estimated midcarpal measurements similar to the radiographs and CT scans.

The model can be used to predict movement through the midcarpal joint on loading.

Further study will delineate disparate measurements calculated from the model. And improve the model’s ability to predict force transfer and kinematics.

Table 1

23 Development of a patient-derived expectations survey for degenerative wrist arthritis surgery

Aviva Wolff, EdD, OT, CHT, Esther Zusstone, BS, Carol Mancuso, MD, Scott Wolfe, MD Hospital for Special Surgery, New York

Purpose: Develop and validate a patient-derived expectations survey for degenerative wrist arthritis surgery. Methods: Patients scheduled for for degenerative wrist arthritis surgery were recruited in-person or by telephone. Inclusion criteria were: scapholunate advanced collapse, scaphoid nonunion advanced collapse, scapholunate interosseous ligament tear, post-traumatic arthritis, and Kienböck disease. The survey was developed in 2 phases. Phase 1: 22 patients were interviewed preoperatively with open-ended questions about their expectations of surgery; a draft survey was assembled by categorizing responses. Phase 2: The survey was administered twice to another group of 27 patients preoperatively to assess test-retest reliability. Concordance was measured with weighted kappa values and intraclass correlations. All patients completed the Patient Rated Wrist Evaluation and Canadian Occupational Performance Measure. Results: Phase 1: 244 expectations were volunteered from which 22 distinct categories were discerned to become items for the draft survey. The final survey items addressed pain, mobility, sports, resumption of functional activities, active lifestyle, future function, and psychological well-being. An overall score is calculated from the number of items expected and the amount of improvement expected, and ranges from 0-100; higher represents increased expectations.

Phase 2: Mean scores for administrations were 74.5(±17.8, range = 37.5-98.9) and 76(±21.2, range 30.7-100). Cronbach alpha coefficients were .91 and .93, and the intraclass correlation coefficient between administrations was .85. The range of endorsement for items was 63%-100%. The range of weighted kappa values was .39-.96, and for 18/22 items the weighted kappa value was > .60.

Conclusions: We developed a patient-derived survey that is reliable and addresses a spectrum of expectations for patients undergoing degenerative wrist arthritis surgery. Information from this tool can be used to define expectations, choose the right treatment, and measure post-operatively how closely expectations have been met.

24 Single Assessment Numeric Evaluation (SANE) in Hand Surgery - Does a One Question Outcome Instrument Compare Favorably?

Jacob D Gire, MD, Jayme C B Koltsov, PhD, Nicole A Segovia, BS, Deborah E Kenney, MS,

Jeffrey Yao, MD, Amy L Ladd, MD

Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Redwood City, CA 94063

Level of Evidence: Therapeutic Level III

Abstract (300 words)

Purpose – Patient-reported outcome measures are increasingly used to measure surgeon performance, but often require lengthy surveys and place a considerable burden on patients. We hypothesized that the one-question Single Assessment Numeric Evaluation (SANE) would be a valid and responsive instrument when compared with the Patient-Reported Outcomes Measurement

Information System upper extremity (PROMIS-UE) and QuickDASH.

Methods – The SANE, PROMIS-UE, and QuickDASH are routinely collected electronically in our

Hand and Upper Extremity Center. To identify our cohort, we used current procedural terminology

(CPT) codes to query our electronic medical record research data repository for the seven most common hand surgery procedures performed over two years from December 2016 to 2018. These procedures include: carpal tunnel release, trigger finger release, carpometacarpal arthroplasty, wrist arthroscopy, distal radius fracture fixation, first dorsal compartment release, and cubital tunnel release. Patients undergoing a single, isolated procedure with questionnaires obtained in the preoperative and/or postoperative time period were included in the analysis. Convergent validity, coverage, and responsiveness for each instrument were assessed.

Results – We identified 214 patients for inclusion. The SANE score correlated strongly with the

QuickDASH and PROMIS-UE. Floor and ceiling effects were <10% at baseline and follow up. Overall, the QuickDASH was the most responsive, followed by SANE and PROMIS-UE, with all three instruments exceeding the acceptable thresholds for responsiveness and demonstrating significant changes pre- to postoperatively. Responsiveness of the instruments varied by procedure, but were acceptable for carpal tunnel release, CMC arthroplasty, wrist arthroscopy, and trigger finger release, with the exception of the PROMIS-UE in carpal tunnel patients, which did not change significantly pre- to postoperatively and did not meet the minimum threshold for responsiveness.

Conclusion –The single item SANE is a reasonable measure to evaluate outcomes in patients undergoing common hand procedures and demonstrates comparable psychometric properties to the

PROMIS-UE and QuickDASH outcome scores.

25 Radiocarpal Dislocation

David J Slutsky MD

Dumontier et al classified radiocarpal dislocations based on the type of ligamentous injury. 1 Group 1 injuries include pure ligamentous radiocarpal dislocations or dislocations with a small radial styloid avulsion fracture. In this group the volar radiocarpal ligaments are torn, which can be assessed arthroscopically through the standard dorsal portals. Posteriorly, the ligamentous injury consists of a capsuloperiosteal avulsion rather than a rupture of the dorsal radiocarpal ligaments per se. Group 2 injuries include dislocations with a large radial styloid fracture fragment 1/3 or more of the scaphoid fossa of the distal radius. Dorsally, the ligamentous injury consists of a capsuloperiosteal avulsion rather than a tear of the dorsal radiocarpal ligaments. Group 1 dislocations consist of a global ligamentous injury, which have the potential for multidirectional instability as compared to Group 2 injuries where the radiocarpal ligaments remain attached to the fractured large radial styloid fragment. Carpal stability can usually be restored with rigid anatomic fixation of the fracture. The most common complications following radiocarpal dislocation or fracture–dislocation include a loss of motion, post traumatic OA and chronic radiocarpal and distal radioulnar instability or ulnar translocation of the carpus.

1. Dumontier C, Meyer zu Reckendorf G, Sautet A, Lenoble E, Saffar P, Allieu Y. Radiocarpal dislocations: classification and proposal for treatment. A review of twenty-seven cases. J Bone Joint Surg Am. 2001; 83:212–218.

26 Analyzing Dogma in the Treatment of Wrist Arthritis

Wagner,E. Purpose: The purpose of this series of studies was to examine the various treatment options and considerations in the treatment of wrist arthritis in high risk patients, such as young, high demand, or those with bilateral disease. I will review projects examining long-term outcomes of proximal row carpectomy (PRC) alone or in comparison with four corner arthrodesis (4CA), bilateral wrist arthrodesis, and finally implant considerations historically in total wrist arthroplasties. PRC Study: In this analysis we analyzed 144 PRCs with a mean follow-up of 13.4 years. Although patients clinically improved and maintained these improvements, factors that improved the clinical outcomes included age >40 years, non-laborers, Kienbock’s disease, concomitant PIN/AIN, and surgery after 1990. The survival-free of fusion was 86% at 20 years, with higher rates of failure in patients >40 years, non-laborers, Kienbock’s disease, and surgery after 1990. Overall 45% developed radiocapitate arthritis, with a higher rate in type 2 and 3 capitates and type 2 lunates. PRC vs 4CA in Young Patients: In the next study we analyzed patients <45 years undergoing 4CA (n=51) at a mean follow-up of 11 years or PRC (n=38) at a mean follow-up of 16 years. Clinically, the only differences were that patients who underwent PRC had improved wrist motion, while 4CA had improved grip strength. The 10 year survival-free of revision surgery was 84% for PRC and 80% for 4CA. There was a higher reoperation rate after 4CA (29%) than PRC (21%). In particular, there were significantly worse outcomes in smokers and laborers after 4CA, but not PRC. Bilateral Wrist Arthrodesis: We examined 13 patients (26 wrists) at a mean follow-up of 14 years who underwent bilateral total wrist arthrodesis. Patients had improvements in their clinical outcomes, with predictable rates of pain relief and overall satisfaction. There was a 19% nonunion rate, with a 69% 10 year survival-free of nonunion. Patients who had worse functional outcomes included those with ipsilateral elbow pathology, increasing age, and smokers. Position of fusion had no impact on functional scores. Total Wrist Arthroplasty: We examined 425 total wrist arthroplasties over a 40 year experience with a mean follow-up of 11 years. There were 109 (26%) revision surgeries performed, while there was an additional 36 reoperations. The most common etiologies leading to revision surgery including distal loosening alone (n=54), dislocation alone (n=28), and distal loosening concomitantly with dislocation (n=4). The 10 and 20-year implant survival rates were 74%, and 63%, respectively. Implant analysis demonstrated that the Meuli had an increased risk of revision surgery and reoperation, the Biaxial implant had an increased risk of revision for distal loosening, while the Swanson had a decreased risk. Patients with inflammatory arthritis had a slightly decreased risk of revision surgery, but this was not significant. The most common postoperative complication was dislocation (n=40), which were higher in the Meuli implants, while lower with the Swanson implants.

27 Rapid Osteophyte Formation is Associated with Increased Dorsal Subluxation of the MC1 in Trapeziometacarpal OA Joseph J. Crisco, PhD1, Amy M. Morton, MSc1, Douglas C. Moore, MS1, Amy L. Ladd, M.D.3, Arnold-Peter C. Weiss, M.D.2 1Bioengineering Laboratory, Department of Orthopaedics, The Warren Alpert Medical School of Brown University and Rhode Island Hospital, 1 Hoppin Street, CORO West Suite 404, Providence, RI 02903. 2Department of Orthopaedics, The Warren Alpert Medical School of Brown University/University Orthopedics, 2 Dudley Street, Suite 200, Providence, RI 02905. 3 Robert A. Chase Hand & Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA, USA. [email protected]

PURPOSE: Subluxation of the first metacarpal (MC1) is a common feature of trapeziometacarpal osteoarthritis (TMC OA) progression. However, the orientation of the TMC joint and the limitations of 2-D radiographies make measurements of subluxation challenging, which has resulted in investigators proposing numerous approaches. With CT images the position of the MC1 with respect to the trapezium can be accurately measured in 3-D. The goal of this study was to quantify the progression of MC1 subluxation in 3-D in a longitudinal, observational study of early thumb TMC OA progression over a six-year period. MATERIAL AND METHODS: Ninety (90) patients with early (Eaton 0/1) TMC OA were recruited and assessed at enrollment (time 0), and at 1.5, 3, 4.5 and 6 yrs. CT scans of the wrists were acquired at each time point and digital models of the trapezia and first metacarpals were analyzed. Osteophyte volume (OP) was quantified via Boolean subtraction of a best-fit healthy bone model and controlled for bone size by a scaling to a median bone model. Subluxation was defined by the location of the centroid of the MC1 articular facet with respect to the trapezium articular coordinate system and reported as percent facet size. The rates of OP formation and subluxation were calculated for each patient via linear fits of the OP and subluxation data across follow-up intervals. Linear regression was used to assess the association between the rates of dorsal subluxation and osteophyte growth. RESULTS: Subluxation in the sagittal plane occurred almost exclusively in the dorsal direction. The rate of sagittal subluxation ranged from 13%/yr. in the dorsal direction to 0.7%/yr. in the volar direction; the mean (±SD) rate of dorsal subluxation was 1.6±2.4%/yr. Radial-volar subluxation ranged from 6.6%/yr in the radial direction to 2.9%/yr in the volar direction. In our 6 years of observation, the average rate of osteophyte growth was 22.0±30.4 mm3/yr. The rate of dorsal subluxation was strongly correlated with the rate of osteophyte growth (Figure 1). There was no correlation between osteophyte growth and subluxation in the radial-ulnar direction (P = 0.72). CONCLUSIONS: Progression of TMC OA, as measured by osteophyte growth, was strongly associated with MC1 subluxation in the dorsal direction, but not in the radial-ulnar direction. ACKNOWLEDGMENTS: This research was supported in part by funding from NIH AR059185

Figure 1. The rate of dorsal subluxation (volar direction negative) over a six-year period significantly (P < 0.0001) increased as the rate of osteophyte growth increased. Gray band is 95% confidence interval.

28 Lunocapitate Fusion vs. Four-Corner Fusion in the Treatment of SLAC Wrist: A Retrospective Comparison of Outcomes

Ather Mirza, MD, Justin Mirza, DO, Terence Thomas, BS, Amanda Milburn, BS

Purpose: A retrospective study was designed to compare clinical outcomes of lunocapitate fusion (LCF) versus 4-corner intercarpal fusion (4CF) for the treatment of Scapholunate Advanced Collapse (SLAC) wrist.

Methods: We retrospectively identified 38 patients (42 cases) seen between July 2007 and January 2017 with SLAC wrist changes. Twenty-nine patients underwent LCF and 13 underwent 4CF. Fusions were carried out with a distal radius bone graft and internal fixation with screws (n=30), staples (n=1), or a combination of screws and staples (n=3). Objective outcomes included time of fusion, return to work time, grip and pinch strength, range of motion, and non-union frequency. Subjective outcomes included the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire.

Results: We report on 42 cases (7 female) with SLAC wrist; mean age of 58 years (Range: 15-85). Average follow-up for both groups was 45 weeks. When comparing LCF and 4CF patients, there was no significant difference in the mean rate of fusion (p = 0.817), range of motion, gross grip and precision pinch strength, or mean return to work time (p = 0.585). Percent recovery of lateral pinch strength was greater in 4CF patients (p < 0.05). Average DASH scores were 28.38 and 20.13 for LCF and 4CF patients, respectively at final follow-up (mean: 2.84-years, range: 0.4-9.23 years). There were three non-unions (7%) for the LCF procedure. These patients underwent subsequent 4CFs and presented with satisfactory outcomes.

Conclusions: LCF and 4CF showed similar clinical outcomes at final follow-up. However, LCF is a less taxing procedure, requiring shorter operating time and a decreased need for bone grafts. This suggests that LCF is the more favorable approach for treating SLAC wrist as it reduces complexity while producing similar results as a 4CF technique.

29 Volar Tilt of the Radial Component in Total Wrist Arthroplasty is Associated with Increasing Wrist Range of Motion

Bardiya Akhbari1, Amy M. Morton2, Kalpit N. Shah2, Douglas C. Moore2, Arnold-Peter C. Weiss2,

Scott W. Wolfe3, Joseph J. Crisco1, 2 1Brown University, Providence, RI, 2Rhode Island Hospital, Providence, RI, 3Hospital for Special Surgery, NewYork, NY [email protected]

PURPOSE: Alignment of knee and hip joint replacements strongly correlate with implant performance, and malalignment is a known contributor to implant failure. The effcts of implant alignment has not been studied in wrist replacements. The aims of this retrospective study were to define the alignment of total wrist arthroplasty (TWA) components using three-dimensional analysis and to determine how alignment affects wrist range of motion (ROM).

MATERIALS AND METHODS: Six non-rheumatoid patients (74.7±5.6 yrs, > 6 mo. post-op. 2F, 2R.) who received Freedom® wrist arthroplasties (Integra LifeSciences) were recruited and consented after IRB approval. CT scans were acquired of each wrist, and the TWA carpal component, third metacarpal, and radius were segmented using Mimics (Materialise, Leuven, BE). A digital model of the radial component was generated using an industrial 3D surface scanner. Biplane videoradiography (BVR) was used to capture implant and wrist motion as each subject moved their wrist in flexion-extension, radial-ulnar deviation, and circumduction. Maximum ROMs in flexion, extension, radial deviation, and ulnar deviation were calculated from the BVR data. Radial component alignment was defined by the orientation of the component coordinate system compared to radius-based anatomic coordinate system in the sagittal, frontal, and axial planes (volar-dorsal tilt, radial-ulnar tilt and pronosupination rotation, respectively). Linear regression was used (p <0.05) to evaluate the correlation between TWA alignment and wrist ROM.

RESULTS: The alignment of the radial components ranged from -3.2° to 6.1° and from -2.8° to 20.0° in the volar-dorsal and radial-ulnar directions, respectively. Linear regression analysis demonstrated that flexion, radial deviation, and ulnar deviation ROMs were significantly (P = 0.06, 0.001, and 0.02, respectively) higher for patients who had a larger volar tilt of the radial component (Figure 1). Radial tilt of the carpal component was also correlated with higher flexion ROM (P = 0.03).

CONCLUSIONS: Larger ranges of flexion-extension and radial-ulnar deviation wrist motion are associated with volarly tilted radial components. The impact of the alignment on the long-term success wrist arthroplasty remains to be investigated. ACKNOWLEDGMENTS: This research was supported in part by funding from NIH P30- GM122732 and American Federation for Surgery of the Hand.

Figure 1. Wrist range-of-motion (ROM) increased as the radial component’s volar tilt increased in this retrospective study of six TWA patients. 30 Differences in Complication Rate between Percutaneous and Mini- open Scaphoid Fracture Repair

Seth D. Dodds, M.D.Augustus J Rush, M.D.Abdul K. Zalikha, M.D.Natalia Fullerton, M.D.

Introduction: Complication rates from percutaneous screw fixation of scaphoid fractures in the reported literature range widely from 0-30%. We retrospectively review of scaphoid fracture repairs from a single surgeon’s practice, comparing percutaneous fixation to mini-open fixation, all from a dorsal approach. We hypothesized more complications in the percutaneous group from inability to directly see scaphoid instrumentation. Methods: We assessed 44 consecutive percutaneous scaphoid fracture repairs (Age 24 +/- 10) and 36 consecutive mini-open scaphoid fracture repairs (Age 30 +/- 16). Complications included intra- operative guide wire breakage, intra-operative fracture, extensor tendon rupture or dysfunction, infection, delayed union, nonunion, persistent pain, radial sensory nerve irritation, CRPS, scar problems, scaphoid screw removal, and intra-articular screw prominence. Results: One intra-op guide wire broke in each group, necessitating a 1 cm incision at the radial aspect of the thenar musculature for removal. There were no problems with intra-op fracture, extensor tendon dysfunction or rupture, infection, nonunion, RSN irritation, CRPS, scar problems, or scaphoid screw removal in either group. One patient in the mini-open group had persistent pain for 6 months post-operatively despite 50% bridging bone on CT scan at 3 months post-operatively. There were 2 screws prominent at the STT joint on plain films in the percutaneous group and one in the mini-open group, all asymptomatic. None of the screws were prominent at the radiocarpal joint. Conclusions: We had 3 complications in the percutaneous group (7%) and 3 complications in the mini-open group (8%), not significantly different, p > 0.05. When contrasting these results to a prior published reports with up to 29% complications (5 major, 2 minor) in 24 patients using a dorsal percutaneous technique, our percutaneous group of 44 patients had a 7% complication rate, all 3 were minor, using their criteria. References: 1. Brandon D. Bushnell, Andrew D. McWilliams, Terry M. Messer, Complications in Dorsal Percutaneous Cannulated Screw Fixation of Nondisplaced Scaphoid Waist Fractures, In The Journal of Hand Surgery, 32(6): 827-833. 2007 2. Fixation of nondisplaced scaphoid fractures: making treatment cost effective. Arora, R. 1; Gschwentner, M. 1; Krappinger, D. 1; Lutz, M. 1; Blauth, M. 1; Gabl, M. Archives of Orthopaedic & Trauma Surgery. 127(1):39-46. 2007. 3. Matson, Andrew P., et al. “Percutaneous Treatment of Unstable Scaphoid Waist Fractures.”Hand, vol. 12, no. 4, 2016, pp. 362–368. 4. Vinnars, B., Af Ekenstam, F., & Gerdin, B. (2007). Comparison of direct and indirect costs of internal fixation and cast treatment in acute scaphoid fractures: A randomized trial involving 52 patients. Acta Orthopaedica, 2007, Vol.78(5), P.672-679.

31 Biomechanical Analysis of Reconstruction of Proximal Pole of the Scaphoid with Proximal Hamate Graft in a Cadaveric Model

Marion Burnier1, MD, Joseph A. Gil1, MD, Alexander Hooke1, MS, Bassem Elhassan1, MD,

Sanjeev Kakar1, MD 1 Mayo Clinic, Rochester, Minnesota

Purpose: To determine if reconstruction of the proximal pole of the scaphoid with a proximal hamate graft restores native carpal kinematics.

Materials and Methods: 8 fresh-frozen mid-forearm cadaver specimens were chosen for this institutionally approved study. Wireless sensors were mounted to the carpus using a custom pin and suture anchor system. The flexor carpi ulnaris, flexor carpi radialis, extensor carpi ulnaris and extensor carpi radialis longus and brevis were loaded during testing. A wrist simulator was used to move the wrist through a cyclical motion about the flexion/extension and radial/ulnar deviation axes. Each specimen was tested under a series of three conditions: 1) a native state, “Intact”; 2) fractured scaphoid proximal pole, “Fracture”; and, 3) post reconstruction of the proximal pole of the scaphoid using a proximal hamate graft and scapholunate ligament repair with the volar capito hamate ligament “Graft”. Kinematic motion was captured using a combination of Moiré Phase Tracking 3D motion tracking sensor hardware (MPT, Metria Innovation, Inc., Milwaukee, WI). Data were collected at 60Hz using The Motion Monitor toolbox software (Innovative Sports Training, Inc., Chicago, IL). The last 5 of the 100 cycles performed were averaged and used for kinematic analysis. Scapholunate, lunocapitate, and scaphoradial kinematics were evaluated during wrist flexion/extension and radial/ulnar deviation motions for each of the three conditions.

Results: The fracture condition resulted in a statistically significant change in scapholunate kinematics across the entire arc of wrist radial-ulnar deviation motion relative to the intact condition (scapholunate flexion: p = 0.005, scapholunate radial-ulnar deviation: p = 0.05- Figure 1). Additionally, the fracture condition resulted in an increase in lunocapitate radial-ulnar deviation during wrist radial ulnar deviation (p = 0.04-Figure 2). Proximal hamate to scaphoid transfer resulted in restoration of carpal kinematics to the intact state.

Conclusions: Proximal pole scaphoid fracture results in altered wrist kinematics. The proximal hamate graft restored scapholunate and lunocaptiate joint native carpal kinematics in a cadaveric model.

Figure 1. Scapholunate flexion extension during wrist radio-ulnar deviation

Figure 2. Lunocapitate radio-ulnar deviation during wrist radio-ulnar deviation.

32 Systematic Review of Non-operative treatment of Kienbock’s

Disease, and report on two cases

Mark S. Anderson, MD1; Bryce N. Clinger, MD1; Moheb S. Moneim, MD1

1Department of Orthopaedics and Rehabilitation, University of New Mexico School of Medicine, Albuquerque, NM 87131

-Purpose: Evaluate patient outcomes after non-operative treatment for Kienbock’s Disease.

-Methods: A systematic review of literature using CINAL, Cochrane and PubMed Databases was performed by the authors. The following keywords were searched: “Kienböck’s Disease”, “Kienböcks Disease”, “Lunatomalacia”, “Aseptic Necrosis of Lunate”, and “Avascular Necrosis of Lunate.” The search was limited to articles published less than 40 years ago and those in English. The bibliographies of all relevant results were manually searched for any additional potential references. The authors also hand searched the Journal of the American Academy of Orthopaedic Surgeons. Duplicates and pediatric articles were removed and abstracts were reviewed for relevance. Each eligible study was independently reviewed in its entirety by two investigators with a third investigator adjudicating in cases of disagreements. Two cases of patients with stage II Kienbock’s Disease on MRI treated conservatively with regular follow up are also presented.

-Results: 10 of 967 articles met inclusion criteria. (Fig.1) Various surgical techniques were compared to nonoperative treatment. It was found that surgery was largely no better than conservative treatment with symptom relief. Wrist mobility, grip strength, and activity modification was also reviewed showing the nonoperative group having better long-term outcomes. The cases of 2 patients with stage II Kienbock’s on MRI treated nonoperatively are also presented. At follow up, patients reported improved pain and function. One patient demonstrated improved vascularity on repeat MRI exam.

-Conclusions: Based off the results of this systematic review along with the successful outcomes of two cases presented by the authors; nonoperative treatment of Kienbock’s Disease may be more beneficial than previously thought or described regardless of the stage of Kienbock’s Disease.

33 Clinical Outcomes of Arthroscopic Treatment of Partial

Scapho-lunate Ligament Tear

Libby Anderson1,,2Mark Ross1,2,3Ruby Strauss1Silvia Manzanero1Benjamin Hope1,2Gregory B Couzens1,4

1. Brisbane Hand and Upper Limb Research Institute, Brisbane, Australia 2. Orthopaedic Department, Princess Alexandra Hospital, Brisbane, Australia 3. University of Queensland, Brisbane, Australia 4. Queensland University of Technology, Brisbane, Australia

Purpose Various wrist arthroscopy techniques can be used in the management of scapho-lunate ligament (SLL) partial tears but their success is not confirmed. We hypothesised that arthroscopic capsular tightening yields reliable and satisfactory results.

Materials and Methods 21 wrists (20 patients) underwent SLL treatment by thermal capsular shrinkage (15 wrists) or dorsal capsular abrasion (6 wrists). 14 wrists had Geissler grade II, two had grade II-III, two had grade I and three had grade III or IV lesions, and all wrists but one had symptoms for greater than 6 months. Pre- and post-operative outcome scores were recorded at 3, 6, 12 and 24 months. Median age at surgery was 40 years (range 18 – 57) and median follow-up time was 12 months (range 3 – 24). Patients were assessed for the following: pain and satisfaction, Patient-Rated Wrist and Hand Evaluation (PRWHE), QuickDASH, Global Rating of Change (GRC), range of motion, grip and pinch strength. Data are reported as median (25% – 75%) and comparisons were drawn between pre-op and last follow-up greater than or equal to 12 months (n=12).

Results Pain decreased from 58 (31 – 71) to 24 (12 – 46) and satisfaction increased from 15 (1 – 35) to 71 (31 – 91). PRWHE and QuickDASH improved from 62 (38 – 75) to 35 (15 – 64) and from 41 (26 – 55) to 30 (5 – 58) respectively. Median grip strength increased from 26 kg (15 – 45) to 32 kg (25 – 45) at final review. Range of movement and pinch strength were satisfactory maintained. Complications were limited to two wrist fusions over a year after surgery, a reinjury at 12 months requiring cortisone injection and a denervation at two years.

Conclusions The data indicate that this procedure is safe and effective but confirmation will require longer term follow-up.

SESSION 4: TFCC

34 Definition, components, and structure of the TFCC. David L. Nelson

Purpose The definition, components, and structure of the TFCC as originally described by Palmer in 1981 and confirmed by Kleinman in 2007, as well as previously published by the current authors, need revision. Materials and methods A literature review of the papers cited by Palmer and prior historical papers from 1742 onwards was performed. A histological analysis of 7 fresh cadaver specimens, gross anatomy specimens, and surgical data was reviewed. Results The term ulnar collateral ligament was found to be firmly established in the anatomic literature as far back as 1742 (Weitbrecht). The term ulnar collateral ligament was repeated in many standard anatomy texts, including texts published in the last 5 years by the ASSH. However, our examination demonstrated that there was no ligament on the ulnar side of the wrist based on histology, gross anatomy, or surgery. There is no ulnar collateral ligament of the wrist. The term meniscus homologue was proposed by Lewis (1970) based only on gross anatomy comparisons of humans and primates. He found a synovial structure which he felt was homologous to a primate meniscus. However, our histological sections in fresh human tissue indicated only loosely oriented fibers in this location, showing a thickened joint capsule. No meniscus-like structure was found. Additionally, gross anatomic dissections and wrist arthroscopy over 28 years also fail to demonstrate any such consistent structure in this area. There is no meniscus homologue of the wrist. The term ligamentum subcruentum was coined by Henle (1872). He stated that this was a vascular structure, not a ligamentous structure. Kleinman in 2007 cited Henle, stating “the ligamentum subcruentum is technically not a ligament at all”, yet went on to state that “it is now commonly used by many investigators as interchangeable with the term ‘deep TFC radioulnar ligaments.’ ” This use of the term ligamentum subcruentum has spread, and was used in the ASSH Self-assessment Exam of 2018. However, Henle, who originated the term, specifically said it was vascular, not ligamentous. Our histological examination confirms Henle's description of bundles of vessels between the superficial and deep radioulnar ligaments. Conclusion Contrary to our previous papers and that of Palmer and of Kleinman, there is no ulnar collateral ligament or meniscus homologue in the wrist, and the term ligamentum subcruentum should be used as it was originally, for a vascular structure and not as a term for the deep ligament. The term “TFCC sensu lato” should be to refer to the description of Palmer and of Kleinman, the term “TFCC sensu strictu “ should be used to refer to the TFCC as described by this paper.

Henle’s 1872 Illustration Grey’s 1858 Anatomy of the Toshi Nakamura’s

of the “lig. Subcruentum” ulnar collateral ligament histology of the 35 Histological Analysis of the TFCC: A Re-Examination on the Meniscus Homologue, Ulnar Collateral Ligament and Ligamentum Subcruentum Toshiyasu Nakamura and David L. Nelson PURPOSE The components of the TFCC were originally defined by Palmer and Werner in 19811, including the meniscus homologue and the ulnar collateral ligament, among other structures. Nakamura et al. in 1996 2 examined the TFCC anatomically and histologically, and defined the functional ulnar collateral ligament as the sheath floor of the ECU and surrounding loose ligamentous structures. Kleinman in 20073 described the ligamentum subcruentum as the deep layer of the RUL. Our experience since the publication of these papers, in both arthroscopic surgery and in the anatomy lab, raised the question as to the existence of the meniscus homologue, the ulnar collateral ligament, or the ligamentum subcruentum, as described by the previously cited authors. The definitions of these 3 structures was determined by a historical study of the authors who originally introduced the terms (this study is the subject of a separate presentation). To clarify existence and nature of these 3 structures, a, histological analysis was again performed. METHODS A histological analysis was performed using 6 fresh frozen cadavers (age 17-44). Before sectioning, each upper extremity was fixed in the neutral position of the forearm with two 1.2 mm diameter K-wires, 2 and 3 cm proximal to the distal radioulnar joint (DRUJ) and the radius and scaphoid were fixed in the neutral position of the wrist with two 1.2 mm diameter K-wires to prevent changes in the ulnar variance or rotation of the DRUJ or wrist position. The wrist was cut 6 cm proximal to the DRUJ, preserved in phosphate buffered 10% formalin, embedded in paraffin, and 10μ coronal sections were made to obtain serial sections from dorsal to volar. Sections were stained with Azan, and light microscopic observation was made. RESULTS The meniscus homologue was noted as internal wall area of distal component of the TFCC, which faced to the triquetrum. These are loosely oriented fibers mostly showing a thickened joint capsule and in the very palmar area the well-oriented fibers to the triquetrum was seen, corresponding to the ulnotriquetral ligament. No meniscus-like structure was found, but there were fibrocartilaginous tissue against the triquetrum in one specimen. This may be fibrocartilaginous transformation by the pressure from the triquetrum. There is no meniscus homologue of the wrist in this analysis. There were loosely-oriented fibers from the ulnar styloid to the triquetrum, without ligamentous insertion neither to the ulnar styloid or the triquetrum. There was adipose tissue just beneath the not well- oriented fibers inside. There is no ligament on the ulnar side of the TFCC based on histology. Our histological examination showed vacant space between the styloid fibers and fovea fibers of the radioulnar ligament which may confirm Henle's description of bundles of vessels between the superficial and deep radioulnar ligaments. SUMMARY Contrary to papers of Palmer, Nakamura and Kleinman, there is no ulnar collateral ligament or meniscus homologue in the human wrist, and the term ligamentum subcruentum should be used as it was originally, for a vascular structure and not as a term for the deep ligament.

1. Palmer AK, Werner FW. The triangular fibrocartilage complex of the wrist--anatomy and function. The Journal of hand surgery. 1981;6(2):153-162. 2. Nakamura T, Yabe Y, Horiuchi Y. Functional anatomy of the triangular fibrocartilage complex. J Hand Surg Br. 1996;21(5):581-586. 3. Kleinman WB. Stability of the distal radioulna joint: biomechanics, pathophysiology, physical diagnosis, and restoration of function what we have learned in 25 years. The Journal of hand surgery. 2007;32(7):1086-1106.

36 Ulnar Head Offset and its Role in DRUJ Stability. Orbay,J.

Purpose: In some cases of DRUJ dysfunction, an ulnar head replacement and soft tissue repair are necessary to provide DRUJ stability. We hypothesize that by incorporating an increased offset in the ulnar head replacement, tension will be increased in the DIOL and stability improved without additional soft tissue repair.

Materials & Methods: We measured stability of cadaveric forearms with push-pull (piano key sign) testing of the DRUJ, by comparing displacement under load (stiffness) of the specimens. We rigidly fixed the ulna and displaced the distal radius at a rate of 0.5mm/sec (up to 10mm of translation or loads of 50N).

We measured specimens in their intact native state, then completely excised the TFCC to simulate DRUJ instability. We replaced the native ulnar head with experimental ulnar heads of the closest possible diameter using two different offsets (standard/ increased).

We defined offset as the distance from the center of ulnar articular surface to the axis of the ulnar shaft. The standard offset head had the same offset as the average native ulnar head of the same diameter. The increased offset head had twice the offset as the average native ulnar head of the same diameter.

Results: Excising the TFCC decreased the average stiffness of the DRUJ to 47.8% of the intact state (p<0.05). Replacing the ulnar head with the standard offset increased average stiffness (relative to the cut state) by 17.6% (p<0.05). Replacing the ulnar head with the increased offset increased average stiffness (relative to the cut state) by 60.1% (p<0.05) restoring stiffness to near intact state.

Conclusions: Increasing the offset in ulnar head replacement improves DRUJ stability. In pronation and supination, the increased offset ulnar head restored DRUJ stiffness near to the intact native state despite no soft tissue repair. We postulate that this increased stability may result from increased soft tissue tension of the DIOL.

37 Biomechanical Evaluation of Distal Radioulnar Joint Instability and Adams Procedure

Frederick W. Werner, Holden D. Heitner, Salvatore M. Cavallaro, Sarah R. Willsey, Brian J. Harley SUNY Upstate Medical University, Syracuse, New York USA

Purpose: DRUJ instability may occur after an injury, resulting in pain, reduced strength, and mechanical difficulties. When primary repair is not possible or initial fixation has failed, resulting in chronic instability, a reconstructive procedure such as the Adams procedure may be performed. The purpose of this study was to quantify the stability of the Adams reconstruction procedure compared to various states of disruption through dynamic forearm supination/pronation and provocative testing.

Methods: Eight fresh cadaver forearms were dynamically moved through an average range of 56.8o of pronation to 54.8 o of supination with the forearm intact, following sectioning of the dorsal (DRUL) and palmar radioulnar ligaments (PRUL), after sectioning of the distal interosseous membrane, after sectioning of the central band, and then after reconstruction using the Adams procedure. During each forearm motion and provocative shuck, the motion of the radius and ulna were measured using an optical motion analysis system and the radial attachments of the DRUL/PRUL/sigmoid notch and ulnar fovea were computed.

Results: Significant increases in the gap between the ulnar fovea and the attachment sites of the DRUL and PRUL were observed with incremental sectioning but especially after sectioning of the central band. Reconstruction significantly reduced the gap at the DRUL and PRUL sites during dynamic motion but slight visual gapping was still observed.

Conclusion: This study reinforces the thinking that DRUJ stability is dependent upon more than just the radioulnar ligaments, ulnocarpal ligaments and TFCC, but also is significantly affected by the distal and central interosseous membrane, as it was only after sectioning the central band that significant differences in gap lengths were seen. Clinical Relevance: These results suggest that the Adams reconstruction is a reasonable option to address DRUJ instability, but is an incomplete solution in the setting of a ruptured interosseous ligament.

38 Ulnar shortening osteotomy as a treatment of symptomatic ulnar impaction syndrome with a new locking plate Sauerbier M, Terzis A Department for Plastic, Hand and Reconstructive Surgery, BG Trauma Center Frankfurt, Germany

Purpose Ulnar impaction syndrome appears due to a pathological ulnar plus variance, which could either be congenital or acquired, most frequently after a malunited distal radius fracture. After failure of conservative treatment and/or arthroscopic ulnocarpal debridement, the treatment of choice is the ulnar shortening in order to decompress the ulnocarpal wrist compartment and restore the biomechanics of the distal radioulnar joint. Aim of this study was to investigate the effectiveness of ulnar shortening osteotomy using a new, low-profile, locking plate with the ulnopalmar approach. Materials and Methods Between June 2016 and March 2019 ulnar shortening osteotomy was performed in 31 patients using a new, low-profile, locking plate with the ulnopalmar approach. 15 patients were female and 16 patients male at a mean age of 45 years. The indication for ulnar shortening was in 14 patients a malunion after distal radius fracture, in 16 patients a congenital positive ulna-plus variance and one patient had a madelung deformity. 25 of the 31 patients underwent a previous arthroscopic ulnocarpal debridement. Ulnar osteotomy was performed in all patients in an ulnopalmar approach with the osteotomy at an angle of 45°. Arc of motion, grip strength (Jamar Dynamometer), pain (Visual Analogue Scale) and activities of daily living (DASH Score) as well as radiological outcome were assessed. Results All of the patients were reevaluated with complete follow-up data in a mean follow-up time of 10.6 months. There was a significant pain reduction (VAS; 7.4 to 2.2, p<0.05) and improvement of function (DASH; 50.44 to 27.4, p<0.05). Range of motion and grip strength improved as well compared to the contralateral side. The mean ulnar shortening was 3.8 mm. Bony union was observed in all patients after a mean time of 10 weeks. Overall patient satisfaction was rated by 29/31 patients as very good, 1/31 as good and 1/31 as not good. There were no implant associated complications. The mean time required to return to work was 3 months. Conclusions Ulnar shortening osteotomy with a new, low-profile, locking plate allows for an exactly defined oblique osteotomy as well as a safe closure of the osteotomy gap using a compression spindle. There was no nonunion or other implant associated complication in our series. Functional early outcome was very good and overall patient satisfaction was high.

39 Ligamentoplasty of the palmar ulnoradial ligament at the DRUJ by bone ligament transplant from the extensor retinaculum -Technique and preliminary results.

Tünnerhoff,H. Marbach, Germany

Purpose: For painful instability of the distal radioulnar joint (DRUJ) in some cases a ligament reconstruction is necessary. The ulnoradial ligaments may be replaced by a free tendon graft either by reconstructing the whole complex or -more simply- by replacing only the ulnar part ascending from the fovea fixing this to the remnants of the ligaments at the radius. In the many cases, in which due to the secondary stabilizers only the palmar translation of the radius in relation to the ulna is clinically evident and needs to be addressed a reconstruction of only the palmar ulnoradial ligament is sufficient. However all these reconstructions using tendons as a graft are prone to secondary loosening. A new technique of a bone ligament transplant to overcome these problems is presented.

Methods: A bone ligament transplant taken from the extensor retinaculum is used. The bone taken as graft by chisels between the 2nd an 3rd compartment is cut to shape by a fine rongeur and pressed by a template block to be a cylinder which fits into a 6,0 mm drill whole made in a oblique direction from the ulnar neck towards the fovea. The exit at the fovea is only drilled to 4 mm, so the exit of this channel is narrower than the entry and the graft is firmly pressed into the bone. The ligamentous part, which includes fibres from the extensor retinaculum towards the 6th and the 1st compartment is grasped by a multiple looped thread and pulled out of the end of the channel in the fovea and is interwoven to the remnants of the palmar ulnoradial ligament under adequate tension. The arm is immobilized for 6 weeks.

Results and Conclusions: From 2016, 7 joints in 6 patients (5 female ,1 male, average age 36 y), all cases of recurrent instability after previous surgery, have been operated by this technique with a minimum of 6 months follow up. All of them regained free motion and stability of their DRUJ. Standard - X rays of the wrist taken after 6 weeks showed good healing of the transplanted bone in all cases. No complications referred to the technique of taking and inserting the graft occurred. In one case an additional ulnar shortening was done at the same time. 5 patients are free of pain, one has a stable joint but pain due to arthritic changes at the radiolunate joint. Replacing the ulnar part of the palmar ulnoradial ligament by a free bone ligament graft from the extensor retinaculum is an option to stabilize the DRUJ in the numerous cases of unidirectional palmar instability (palmar subluxation of the radius against the ulnar head).

Keywords: DRUJ, instability, ligament reconstruction, bone ligament graft

40 Open repair of chronic Triangular Fibrocartilage Complex injuries utilizing volar approach and pinning: 10 cases. Dodds, SD. Greene, JD.

Purpose: To describe the outcomes after surgical management of chronic distal radioulnar joint (DRUJ) instability using an open volar surgical approach for repair of the triangular fibrocartilage complex (TFCC) foveal tear and temporary arthrodesis of the DRUJ.

Methods: We conducted a retrospective case review of 10 patients with foveal tears. All patients underwent open repair of the TFCC using a previously described volar surgical approach and temporary arthrodesis of the DRUJ using two kirschner wires, which were removed 8 weeks later. Pain, instability, and arc of motion were evaluated at final follow up.

Results: Patients ranged from 16 to 56 years old. All patients reported mild to moderate pain on initial exam. Average chronicity of injury prior to surgery was 3 months (range 0.5-8 mo), where one patient had acute on chronic presentation of DRUJ instability, and one patient had underwent prior open dorsal surgical approach for attempted repair of TFCC. Two patients were participants in worker’s compensation claims. Average follow up was 6 months (range 0-17.5 mo), with one patient lost to follow up. All patients seen in clinic for follow up had a stable DRUJ on clinical exam. Average forearm rotation was 61° supination to 63.5° pronation (average total arc of motion 124°). All but one patient’s pain scores improved to no to mild pain at final follow up, and this patient had radiologic evidence of DRUJ osteoarthritis.

Conclusion: In cases of chronic DRUJ instability greater than 3 months, pinning the DRUJ after TFCC repair leads to consistent and reliable improved outcomes post-operatively regarding pain, stability, and final arc of motion.

41 Clinical Case: TFCC Guillaume Herzberg, Marion Burnier, Lyon France

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