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Background: Controversy exists regarding the optimal technique of subscapularis tendon mobilization during shoulder arthroplasty. The purpose of the present randomized double-blind study was to compare two of these techniques-lesser tuberosity osteotomy and subscapularis peel-with regard to muscle strength and functional outcomes.Methods: Patients undergoing shoulder arthroplasty were randomized to undergo either a lesser tuberosity osteotomy or a subscapularis peel. The primary outcome was subscapularis muscle strength as measured with an electronic handheld dynamometer at twenty-four months postoperatively. Secondary outcomes included the Western Ontario Osteoarthritis of the Shoulder Index and American Shoulder and Elbow Surgeons scores. A sample size calculation determined that eighty-six patients provided 90% power with a 0.79 effect size to detect a significant difference between groups.Results: Forty-three patients were allocated to subscapularis osteotomy, and forty-four patients were allocated to subscapularis peel. Eighty-three percent of the study cohort returned for the twenty-four-month follow-up. The primary outcome of subscapularis muscle strength at twenty-four months revealed no significant difference (p = 0.131) between the lesser tuberosity osteotomy group (mean [and standard deviation], 4.4 ± 2.9 kg) and the subscapularis peel group (mean, 5.5 ± 2.6 kg). Comparison of secondary outcomes, including the Western Ontario Osteoarthritis of the Shoulder Index and American Shoulder and Elbow Surgeons scores, demonstrated no significant differences between groups at any time point. Compared with baseline measures, mean subscapularis muscle strength, Western Ontario Osteoarthritis of the Shoulder Index score, and American Shoulder and Elbow Surgeons score all improved significantly in both groups at twenty-four months (p < 0.001).Discussion: No significant differences in the primary or secondary outcomes of function were identified between the lesser tuberosity osteotomy group and the subscapularis peel group. For the parameters investigated, this trial does not demonstrate any clear advantage of one subscapularis treatment technique over the other. [ABSTRACT FROM AUTHOR]

Background: This clinical trial was done to evaluate outcomes of the single and double-incision techniques for acute distal biceps tendon repair. We hypothesized that there would be fewer complications and less short-term pain and disability in the two-incision group, with no measureable differences in outcome at a minimum of one year postoperatively.Methods: Patients with an acute distal biceps rupture were randomized to either a single-incision repair with use of two suture anchors (n = 47) or a double-incision repair with use of transosseous drill holes (n = 44). Patients were followed at three, six, twelve, and twenty-four months postoperatively. The primary outcome was the American Shoulder and Elbow Surgeons (ASES) elbow score. Secondary outcomes included muscle strength, complication rates, and Disabilities of the Arm, Shoulder and Hand (DASH) and Patient-Rated Elbow Evaluation (PREE) scores.Results: All patients were male, with no significant differences in the mean age, percentages of dominant hands affected, or Workers' Compensation cases between groups. There were also no differences in the final outcomes (at two years) between the two groups (p = 0.4 for ASES pain score, p = 0.10 for ASES function score, p = 0.3 for DASH score, and p = 0.4 for PREE score). In addition, there were no differences in isometric extension, pronation, or supination strength at more than one year. A 10% advantage in final isometric flexion strength was seen in the patients treated with the double-incision technique (104% versus 94% in the single-incision group; p = 0.01). There were no differences in the rate of strength recovery. The single-incision technique was associated with more early transient neurapraxias of the lateral antebrachial cutaneous nerve (nineteen of forty-seven versus three of forty-three in the double-incision group, p < 0.001). There were four reruptures, all of which were related to patient noncompliance or reinjury during the early postoperative period and appeared to be unrelated to the fixation technique (p = 0.3).Conclusions: There were no significant differences in outcomes between the single and double-incision distal biceps repair techniques other than a 10% advantage in final flexion strength with the latter. Most complications were minor, with a significantly greater prevalence in the single-incision group. [ABSTRACT FROM AUTHOR]

Background: The remplissage procedure may be performed as an adjunct to Bankart repair to treat recurrent glenohumeral dislocation associated with an engaging Hill-Sachs humeral head defect. The purpose of this in vitro biomechanical study was to examine the effects of the remplissage procedure on glenohumeral joint motion and stability.Methods: Cadaveric shoulders (n = 8) were mounted on a biomechanical testing apparatus that applies simulated loads to the rotator cuff and the anterior, middle, and posterior heads of the deltoid muscle. Testing was performed with the shoulder intact, after creation of the Bankart lesion, and after repair of the Bankart lesion. In addition, testing was performed after Bankart repair with and without remplissage in shoulders with 15% and 30% Hill-Sachs defects. Shoulder motion and glenohumeral translation were recorded with an optical tracking system. Outcomes measured included stability (joint stiffness and defect engagement) and internal-external glenohumeral rotational motion in adduction and in 90° of composite shoulder abduction.Results: In specimens with a 15% Hill-Sachs defect, Bankart repair combined with remplissage resulted in a significant reduction in internal-external range of motion in adduction (15.1° ± 11.1°, p = 0.039), but not in abduction (7.7° ± 9.9, p = 0.38), compared with the intact condition. In specimens with a 30% Hill-Sachs defect, repair that included remplissage also significantly reduced internal-external range of motion in adduction (14.5° ± 11.3°, p = 0.049) but not in abduction (6.2° ± 9.3°, p = 0.60). In specimens with a 15% Hill-Sachs defect, addition of remplissage significantly increased joint stiffness compared with isolated Bankart repair (p = 0.038), with the stiffness trending toward surpassing the level in the intact condition (p = 0.060). In specimens with a 30% Hill-Sachs defect, addition of remplissage restored joint stiffness to approximately normal (p = 0.41 compared with the intact condition). All of the specimens with a 30% Hill-Sachs defect engaged and dislocated after Bankart repair alone. The addition of remplissage was effective in preventing engagement and dislocation in all specimens. None of the specimens with a 15% Hill-Sachs defect engaged or dislocated after Bankart repair.Conclusions: In this experimental model, addition of remplissage provided little additional benefit to a Bankart repair in specimens with a 15% Hill-Sachs defect, and it also reduced specific shoulder motions. However, Bankart repair alone was ineffective in preventing engagement and recurrent dislocation in specimens with a 30% Hill-Sachs defect. The addition of remplissage to the Bankart repair in these specimens prevented engagement and enhanced stability, although at the expense of some reduction in shoulder motion. [ABSTRACT FROM AUTHOR]

Background: Insertion of a radial head implant that results in radial overlengthening has been associated with altered elbow kinematics, increased radiocapitellar joint forces, capitellar erosions, early-onset arthritis, and loss of elbow flexion. The purpose of this study was to identify clinical and radiographic features that may be used to diagnose overlengthening of the radius intraoperatively and on postoperative radiographs.Methods: Radial head implants of varying thicknesses were inserted into seven cadaver specimens, which were then assessed clinically and radiographically. Eight stages were examined: the intact specimen (stage 1); repair of the lateral collateral ligament (stage 2); radial head resection with repair of the lateral collateral ligament (stage 3); insertion of an implant of the correct thickness (stage 4); and insertion of an implant that resulted in radial overlengthening of 2 mm (stage 5), 4 mm (stage 6), 6 mm (stage 7), or 8 mm (stage 8). The specimens were tested with and without muscle loading to simulate resting muscle tone and surgical paralysis, respectively. At each stage, radiographs were made to measure the ulnohumeral joint space and the lateral ulnohumeral joint was visually assessed.Results: We identified no difference, with regard to medial ulnohumeral joint incongruity as seen radiographically, among stages 1 through 6 during the tests with muscle loading. A significant difference in medial ulnohumeral joint incongruity was found in stages 7 (p = 0.003) and 8 (p < 0.001). The clinical (visually assessed) lateral ulnohumeral joint space gap was negligible in stages 1 through 4 but increased significantly at all stages involving overlengthening (gross gap, 0.9 mm with 2 mm of erlengthening [p = 0.005], 2.3 mm with 4 mm of overlengthening [p < 0.001], 3.4 mm with 6 mm [p < 0.001], and 4.7 mm with 8 mm [p < 0.001]).Conclusions: Incongruity of the medial ulnohumeral joint becomes apparent radiographically only after overlengthening of the radius by ≥6 mm. Intraoperative visualization of a gap in the lateral ulnohumeral joint is a reliable indicator of overlengthening following the insertion of a radial head prosthesis. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Prospective cohort study with repeated measures. OBJECTIVE: To establish the responsiveness of the Simple Shoulder Test (SST) in comparison to other commonly used clinical outcomes in patients undergoing shoulder arthroplasty. BACKGROUND: Responsiveness statistics are a useful means to compare different outcomes in terms of their ability to detect clinical change. While the responsiveness of the SST has been established for rotator cuff repair, it has not been determined for patients undergoing arthroplasty. METHODS: Patients undergoing shoulder arthroplasty (n = 120) were evaluated prior to surgery and 6 months after. The evaluation included the SST, Disabilities of the Arm, Shoulder and Hand questionnaire, range of motion, and isometric strength. Responsiveness to change was assessed using standardized response mean (SRM), while longitudinal construct validity was evaluated using Pearson correlation. Receiver operating characteristics curves were plotted to determine clinically important difference of SST. RESULTS: The SST and Disabilities of the Arm, Shoulder and Hand questionnaire were highly responsive (SRM, >1.70) for this population. For the assessment of impairment, range of motion (SRM, 0.64-1.03) was moderately to highly responsive, while isometric strength was minimally to moderately responsive (SRM, 0.32-0.69). The clinically important difference of the SST was established at 3.0 SST points. Pearson correlations indicated moderate associations between the change scores of the SST and the Disabilities of the Arm, Shoulder and Hand questionnaire (r = 0.49). CONCLUSIONS: The SST has been previously shown to be valid and highly reliable. The present results show that the SST is also responsive following shoulder arthroplasty and that it has a clinically important difference of 3.0 SST points. This should provide confidence to clinicians who wish to use a brief shoulder-specific measure in their practice.J Orthop Sports Phys Ther 2010;40(7):413-421, Epub 15 April 2010. doi:10.2519/jospt.2010.3209. [ABSTRACT FROM AUTHOR]

Distal humerus fractures are common and represent 2% of all fractures and approximately 30% of those affecting the humerus. The management of distal humerus fractures is complicated by the complex 3-dimensional anatomy of the elbow, the limited bone stock for internal fixation, and often comminuted and osteopenic nature of the articular segment. Surgical treatment should be conducted in a systematic manner to minimize complications. Using the principles of anatomic articular reconstruction with stable fixation to allow early range to motion, good to satisfactory outcomes can be expected in most patients. Copyright © 2010 by Elsevier Inc. [ABSTRACT FROM AUTHOR]

Correct identification of the center point of the glenoid surface guides glenoid component placement. It is unknown whether the center point on the glenoid surface corresponds to the center of the glenoid vault at the medial extent of the glenoid prosthesis. We reviewed 20 consecutive computed tomography scans obtained preoperatively in patients with primary osteoarthritis. A glenoid center point was chosen on the glenoid surface and then projected back into the glenoid vault along the scapular axis and perpendicular to glenoid inclination. The difference from the projection of the glenoid surface center point to the center point at a 1.5-cm depth into the glenoid vault was then measured. The mean deviation of the glenoid center point at a depth of 1.5 cm from the center point at the glenoid articular surface was 1.7 mm anterior and 3.9 mm inferior. The most common deviation of the center point of the glenoid vault at the projected medial limit of the glenoid prosthesis was slightly anterior and inferior to the center point on the glenoid surface. Identifying the center of the glenoid surface coupled with alignment of the glenoid prosthesis in neutral version and anatomic inclination provides a reliable means to guide placement of glenoid components. [ABSTRACT FROM AUTHOR]

Clostridium perfringens is a rare, life-threatening infection. We present an atypical evolution of spontaneous Clostridium perfringens myonecrosis in a monitored healthy patient. After a head injury, the hemodynamically stable patient became febrile and grew cultures of Clostridium perfringens with no identifiable focus. Antibiotics were initiated. Seventy-two hours after culture results, the patient complained of shoulder pain and imaging revealed periscapular subcutaneous emphysema. Multiple surgical débridements of the necrotic supraspinatus muscle were required to eradicate the infection. The unique features of this patient include the opportunity to (1) follow the progression of clostridial myonecrosis in a healthy patient in a monitored setting and (2) study the extended period of time between positive cultures and the onset of clinical myonecrosis, a feature at odds with the classic rapid progression. [ABSTRACT FROM AUTHOR]

Background: Fractures of total elbow arthroplasty components are uncommon, and the literature provides little guidance regarding the management and outcomes of treatment of these complications. The goal of this report was to investigate the prevalence and management of fractures of ulnar and humeral components following total elbow arthroplasty and to review our experience with cement-within-cement reconstruction for revision following such fractures.Methods: Between 1979 and 2003, twenty-four patients with a total of twenty-seven fractured total elbow arthroplasty components (seventeen ulnar and ten humeral) of different designs presented to our institution. Twenty-six implants underwent subsequent revision elbow arthroplasty at our institution. Fourteen of those revisions were done with a cement-within-cement technique, and twelve, with traditional methods. Twenty-one patients (twenty-three implants) were available for final follow-up, and data that had been acquired prospectively and entered into the institutional arthroplasty database were reviewed retrospectively. At the time of final follow-up, the Mayo Elbow Performance Score (MEPS) was calculated and preoperative, postoperative, and most recent radiographs were examined for bone loss, bushing wear, and integrity of the bone-cement interface.Results: The prevalences of humeral and ulnar component fracture following primary total elbow arthroplasties performed at our institution were 0.65% and 1.2%, respectively. At a mean of 5.1 years following revisions for those fractures, the MEPS was excellent for eight patients, good for five, fair for six, and poor for two. The average MEPS was 82 points following the revision total elbow arthroplasties done with the cement-within-cement technique and 78 points following the revisions done with the traditional method of cement removal and insertion of a revision component. Complications included seven intraoperative cortical perforations; five nerve injuries, two of which were permanent; three triceps avulsions; and one deep infection.Conclusions: Implant fractures following total elbow arthroplasty are uncommon. They occur for several reasons, such as notch sensitivity, component design, and high stresses due to bone deficiency. Revision techniques, such as cement-within-cement reimplantation, are reliable for relieving pain and restoring function; however, the rate and spectrum of complications are a cause for concern.Level Of Evidence: Therapeutic Level IV. [ABSTRACT FROM AUTHOR]

A computer-assisted technique using computed tomography and three-dimensional imaging for the localization and excision of osteoid osteoma allows minimal bone resection, shortened hospital stay, and prompt weight bearing. [ABSTRACT FROM AUTHOR]

Background: Knowledge of premorbid glenoid parameters at the time of shoulder arthroplasty, such as inclination, version, joint line position, height, and width, can assist with implant selection, implant positioning, metal augment sizing, and/or bone graft dimensions. The objective of this study was to validate a scapular statistical shape model (SSM) in predicting patient-specific glenoid morphology in scapulae with clinically relevant glenoid erosion patterns., Methods: Computed tomography scans of 30 healthy scapulae were obtained and used as the control group. Each scapula was then virtually eroded to create 7 erosion patterns (Walch A1, A2, B2, B3, D, Favard E2, and E3). This resulted in 210 uniquely eroded glenoid models, forming the eroded glenoid group. A scapular SSM, created from a different database of 85 healthy scapulae, was then applied to each eroded scapula to predict the premorbid glenoid morphology. The premorbid glenoid inclination, version, height, width, radius of best-fit sphere, and glenoid joint line position were automatically calculated for each of the 210 eroded glenoids. The mean values for all outcome variables were compared across all erosion types between the healthy, eroded, and SSM-predicted groups using a 2-way repeated measures analysis of variance., Results: The SSM was able to predict the mean premorbid glenoid parameters of the eroded glenoids with a mean absolute difference of 3° ± 2° for inclination, 3° ± 2° for version, 2 ± 1 mm for glenoid height, 2 ± 1 mm for glenoid width, 5 ± 4 mm for radius of best-fit sphere, and 1 ± 1 mm for glenoid joint line. The mean SSM-predicted values for inclination, version, height, width, and radius were not significantly different than the control group (P > .05)., Discussion: An SSM has been developed that can reliably predict premorbid glenoid morphology and glenoid indices in patients with common glenoid erosion patterns. This technology can serve as a useful template to visually represent the premorbid healthy glenoid in patients with severe glenoid bony erosions. Knowledge of the premorbid glenoid preoperatively can assist with implant selection, positioning, and sizing., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Accurate insertion of the glenoid guide pin in shoulder arthroplasty (RSA) is important for obtaining optimized glenoid component position and orientation. The objective of this study was to evaluate and compare the accuracy of 3 glenoid guide pin insertion techniques: (1) traditional software planning using freehand guide pin insertion (freehand), (2) guide pin insertion utilizing patient-specific instrumentation (PSI), and (3) using a mixed-reality navigation (MR-NAV) system., Methods: Twenty (20) computed tomography (CT) scans were obtained from patients exhibiting glenoid erosion patterns according to the Walch and Favard classifications. Cases were planned using validated 3-dimensional (3D) preoperative planning software. The CT data were then used to 3D print triplicate plastic models of each glenoid to evaluate the 3 guide pin insertion techniques. The first technique employed traditional software planning with freehand guide pin insertion. The second method used preoperatively planned PSI guides, whereas the third used an MR-NAV system, which provided real-time holographic guidance during guide pin insertion. Once all guide pins had been inserted into the models, an independent optical tracking system and custom digitization device was used to quantify the position and orientation of each guide pin relative to the glenoid. The outcomes for this study included the absolute mean error in guide pin inclination, version, and entry point relative to the preoperative plan. The absolute Total Global Error was also assessed, which was defined as the sum of the absolute guide pin orientation and position error relative to the preoperative plan., Results: No statistically significant differences between MR-NAV and PSI were found for the inclination error (2° ± 1° vs. 2° ± 1°; P = .056), version error (1° ± 1° vs. 1° ± 1°; P > .99), and Total Global Error (5 ± 1 [mm + deg] vs. 5 ± 1 [mm + deg], P > .99), respectively. The freehand technique produced significantly greater error than MR-NAV and PSI for inclination (5° ± 3°, P ≤ .017), version (4° ± 3°, P ≤ .032), and Total Global Error (8 ± 3 [mm + deg], P < .001). No statistically significant differences in the entry point error were observed between all guide pin insertion methods (P ≥ .058)., Discussion: These results demonstrate that the precision and accuracy of MR-NAV is comparable to PSI and superior to a freehand technique for glenoid guide pin insertion in vitro. Further study is needed to compare the accuracy of these techniques intraoperatively, in addition to assessing a potential learning curve between surgeons of varying experience with the MR-NAV system., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: In 1993, Kouvalchouk described an acromial bone block with a pedicled deltoid flap for the treatment of posterior shoulder instability. This procedure provides a "double blocking" effect in that the acromial autograft restores posterior glenoid bone loss and the deltoid flap functions as a muscular "hammock" resembling the sling effect of the conjoint in the Latarjet procedure. The primary aim of this study was to compare the Kouvalchouk procedure to distal tibial allograft (DTA) reconstruction for the management of posterior shoulder instability with associated bone loss, while the secondary aim was to evaluate the deltoid hammock effect., Methods: Ten upper extremity cadavers were evaluated using a validated shoulder testing apparatus in 0° and 60° of glenohumeral abduction in the scapular plane. Testing was first performed on the normal shoulder state and was followed by the creation of a 20% posterior glenoid defect. Subsequently, the Kouvalchouk and DTA procedures were conducted. Forces of 0N, 5N, 10N, and 15N were applied to the posterior deltoid tendinous insertion on the Kouvalchouk graft along the physiological muscle line-of-action to evaluate the 'hammock" effect of this procedure. Testing was additionally performed on the Kouvalchouk bone graft with the deltoid muscle sectioned from its bony attachment. For all test states, a posteriorly directed force was applied to the humeral head perpendicular to the direction of the glenoid bone defect, with the associated translation quantified using an optical tracking system. The outcome variable was posterior translation of the humeral head at an applied force magnitude of 30N., Results: The Kouvalchouk procedure with the loaded deltoid flap (10N: P = .039 and 15N: P < .001) was significantly better at reducing posterior humeral head translation than the DTA. Overall, increased glenohumeral stability was observed with increased force applied to the posterior deltoid flap in the Kouvalchouk procedure. The 15 N Kouvalchouk was most effective at preventing posterior humeral translation, and the difference was statistically significant compared with the 20% glenoid defect (P = .003), detached Kouvalchouk (P < .001), and 0N Kouvalchouk (P < .001). The 15 N Kouvalchouk procedure restored posterior shoulder joint stability to near normal levels, such that it was not significantly different from the intact state (P = .203)., Conclusions: The Kouvalchouk procedure with load applied to the deltoid was found to be biomechanically superior to the DTA for the management of posterior shoulder instability with associated bone loss. Additionally, the results confirmed the presence and effectiveness of the deltoid "hammock" effect., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Purpose: The aim of this study was to develop and train a machine learning (ML) algorithm to create a clinical decision support tool (i.e., ML-driven probability calculator) to be used in clinical practice to estimate recurrence rates following an arthroscopic Bankart repair (ABR)., Methods: Data from 14 previously published studies were collected. Inclusion criteria were (1) patients treated with ABR without remplissage for traumatic anterior shoulder instability and (2) a minimum of 2 years follow-up. Risk factors associated with recurrence were identified using bivariate logistic regression analysis. Subsequently, four ML algorithms were developed and internally validated. The predictive performance was assessed using discrimination, calibration and the Brier score., Results: In total, 5591 patients underwent ABR with a recurrence rate of 15.4% (n = 862). Age <35 years, participation in contact and collision sports, bony Bankart lesions and full-thickness rotator cuff tears increased the risk of recurrence (all p < 0.05). A single shoulder dislocation (compared to multiple dislocations) lowered the risk of recurrence (p < 0.05). Due to the unavailability of certain variables in some patients, a portion of the patient data had to be excluded before pooling the data set to create the algorithm. A total of 797 patients were included providing information on risk factors associated with recurrence. The discrimination (area under the receiver operating curve) ranged between 0.54 and 0.57 for prediction of recurrence., Conclusion: ML was not able to predict the recurrence following ABR with the current available predictors. Despite a global coordinated effort, the heterogeneity of clinical data limited the predictive capabilities of the algorithm, emphasizing the need for standardized data collection methods in future studies., Level of Evidence: Level IV, retrospective cohort study., (© 2024 The Author(s). Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Summary: Monteggia fracture is a complex fracture consisting of a proximal ulna fracture with a dislocation of the radial head. This review article highlights the relevant anatomy, clinical evaluation, classification, surgical management, recent innovation, and advancements with treating these injuries. A thorough understanding of these fractures allows for detailed operative plans and reconstitution of normal anatomy., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Managing persistent elbow instability and chronic dislocations presents challenges despite traditional treatments. Supplementary methods like immobilization and various fixations, though common, can carry high complication rates. This study assesses the efficacy of bridge plating in treating complex elbow instability through a retrospective review of patients. Data on characteristics, treatment duration, range of motion, complications, and evaluation scores were analyzed, providing insights into outcomes complications associated with bridge plating., Results: Eleven patients were reviewed at a mean follow-up of 80 ± 68 weeks postoperatively. The mean age was 53 ± 14 years and there were 5 females and 6 males. The mean body mass index was 38. Bridge plating was used for a spectrum of complex elbow injuries. The mean time from injury to bridge plating in acute cases was 29 ± 19 days and 344 ± 381 days in chronic cases. The mean duration of bridge plating was 121 ± 72 days. At the time of plate removal, mean intraoperative elbow motion was extension 58° ± 12°, flexion 107° ± 14°, supination 66° ± 23° and pronation 60° ± 26°. At the latest follow-up visit, mean elbow motion was extension 37° ± 22°, flexion 127° ± 17°, supination 72° ± 15°, and pronation 63° ± 18°. There were 6 complications (55%): heterotopic ossification, ulnar neuropathy, wound failure over the plate in a thin patient, an ulnar shaft periprosthetic fracture due to a seizure-induced fall, and persistent elbow subluxation despite bridge plate fixation. Finally, 1 patient sustained a fracture of a 3.5-mm locking bridge plate. One patient required a contracture release for persistent stiffness. Four of these complications can be directly attributed to the use of the bridge plate (36%). At final follow-up, the mean patient-rated elbow evaluation score was 34, with 0 indicating no pain and disability. The mean Single Assessment Numeric Evaluation score was 66% for the 8 patients who had this available, with 100% being the best possible attainable score., Conclusion: Bridge plating effectively maintains joint reduction in selected complex elbow instability cases. However, patients with bridge plates often require a second surgery for removal and experience high rates of general complications because of the complexity of their condition., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Massive irreparable rotator cuff tears (MIRCTs) treated with superior capsular reconstruction (SCR) using the long head of the biceps tendon have shown satisfactory early results. Different techniques and positions for biceps tenodesis have been described. This study aimed to evaluate the effect of tenodesis location and glenohumeral fixation angle for graft tensioning on the biomechanics of an SCR using a single-strand biceps technique., Methods: Eight cadaveric shoulders were mounted onto a custom biomechanical simulator that used static tone loads to the deltoid and rotator cuff muscles. All cadavers were first tested in the intact condition, and then in the simulated MIRCT condition by sectioning the tendinous insertions of the supraspinatus and upper border of the infraspinatus. SCR using the long head of the biceps tendon was then evaluated. Three biceps tenodesis locations relative to the greater tuberosity (anterior, middle, and posterior) and 2 glenohumeral fixation angles (0° and 30°) for graft tensioning were tested. An optical tracking system was used to quantify superior-inferior and anterior-posterior humeral head translation relative to the glenoid, whereas the functional abduction force was quantified using a load sensor. All tests were conducted at 0°, 30°, and 60° of glenohumeral abduction in a randomized fashion., Results: When assessing isolated superior humeral head migration, all biceps tenodesis locations were effective at decreasing superior migration, with no tenodesis location significantly better than the other (P = .213). However, biceps grafts tensioned at 30° of glenohumeral abduction were significantly better at reducing proximal humeral migration as compared to graft tensioning at 0° abduction (P = .008). Posterior humeral head translation observed in the MIRCT condition was significantly reduced when tensioning the biceps tendon at 30° of glenohumeral abduction compared with 0° for all tenodesis locations (P ≤ .043). The tenodesis location also significantly influenced posterior humeral head translation (P = .001), with the middle and posterior positions restoring near normal humeral head position when fixed at 30° glenohumeral abduction. All SCR techniques using the biceps tendon improved the functional abduction force relative to the MIRCT condition, although no statistically significant differences were observed relative to the intact condition (P ≥ .448)., Discussion: SCR using the long head of the biceps tendon is biomechanically effective in reducing posterosuperior translation of the humeral head in the setting of an MIRCT. Graft tensioning and fixation at 30° of glenohumeral abduction combined with either a middle or posterior tenodesis location on the greater tuberosity most effectively restores near normal time-zero humeral head kinematics., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Reverse total shoulder arthroplasty (RTSA) accounts for over half of shoulder replacement surgeries. At present, the optimal position of RTSA components is unknown. Previous biomechanical studies have investigated the effect of construct placement to quantify mobility, stability and functionality postoperatively. While studies have provided valuable information on construct design and surgical placement, they have not systematically evaluated the importance of scapular morphology on biomechanical outcomes. The aim of this study was to assess the influence of scapular morphology variation on RTSA biomechanics using statistical models, musculoskeletal modeling and predictive simulation. The scapular geometry of a musculoskeletal model was altered across six modes of variation at four levels (±1 and ±3 SD) from a clinically derived statistical shape model. For each model, a standardized virtual surgery was performed to place RTSA components in the same relative position on each model then implemented in 50 predictive simulations of upward and lateral reaching tasks. Results showed morphology affected functional changes in the deltoid moment arms and recruitment for the two tasks. Variation of the anatomy that reduced the efficiency of the deltoids showed increased levels of muscle force production, joint load magnitude and shear. These findings suggest that scapular morphology plays an important role in postoperative biomechanical function of the shoulder with an implanted RTSA. Furthermore a "one-size-fits-all" approach for construct surgical placement may lead to suboptimal patient outcomes across a clinical population. Patient glenoid as well as scapular anatomy may need to be carefully considered when planning RTSA to optimize postoperative success., (© 2024 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

The Latarjet procedure is a frequently used stabilization procedure in case of anterior shoulder instability with critical glenoid bone loss and/or off-track Hill Sachs lesions. Although uncommon, intra-operative graft fractures do occur. When confronted with this potentially challenging intra-operative complication, having a secondary solution is paramount to achieve a successful outcome. This technical note provides a treatment algorithm that may function as a useful guideline to assist surgeons that experience this potentially complex unintended event during a Latarjet procedure. LEVEL OF EVIDENCE: Level IV, therapeutic case series., (Copyright © 2024. Published by Elsevier Masson SAS.)

Background: Mixed reality may offer an alternative for computer-assisted navigation in shoulder arthroplasty. The purpose of this study was to determine the accuracy and precision of mixed-reality guidance for the placement of the glenoid axis pin in cadaver specimens. This step is essential for accurate glenoid placement in total shoulder arthroplasty., Methods: Fourteen cadaveric shoulders underwent simulated shoulder replacement surgery by 7 experienced shoulder surgeons. The surgeons exposed the cadavers through a deltopectoral approach and then used mixed-reality surgical navigation to insert a guide pin in a preplanned position and trajectory in the glenoid. The mixed-reality system used the Microsoft Hololens 2 headset, navigation software, dedicated instruments with fiducial marker cubes, and a securing pin. Computed tomography scans obtained before and after the procedure were used to plan the surgeries and determine the difference between the planned and executed values for the entry point, version, and inclination. One specimen had to be discarded from the analysis because the guide pin was removed accidentally before obtaining the postprocedure computed tomography scan., Results: Regarding the navigated entry point on the glenoid, the mean difference between planned and executed values was 1.7 ± 0.8 mm; this difference was 1.2 ± 0.6 mm in the superior-inferior direction and 0.9 ± 0.8 mm in the anterior-posterior direction. The maximum deviation from the entry point for all 13 specimens analyzed was 3.1 mm. Regarding version, the mean difference between planned and executed version values was 1.6° ± 1.2°, with a maximum deviation in version for all 13 specimens of 4.1°. Regarding inclination, the mean angular difference was 1.7° ± 1.5°, with a maximum deviation in inclination of 5°., Conclusions: The mixed-reality navigation system used in this study allowed surgeons to insert the glenoid guide pin on average within 2 mm from the planned entry point and within 2° of version and inclination. The navigated values did not exceed 3 mm or 5°, respectively, for any of the specimens analyzed. This approach may help surgeons more accurately place the definitive glenoid component., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Stemless humeral components are being clinically investigated for reverse shoulder arthroplasty (RSA) procedures. There is, however, a paucity of basic science literature on the surgical parameters that influence the success of these procedures. Therefore, this cadaveric biomechanical study evaluated the neck shaft angle (NSA) of implantation on the survivability and performance of stemless RSA humeral components during cyclical loading., Methods: Twelve paired cadaveric humeri were implanted with stemless RSA humeral components at NSAs of 135° and 145°. Implant-bone motion at the periphery of the implant was measured with 3 optical machine vision USB3 cameras outfitted with c-mount premium lenses and quantified with ProAnalyst software. A custom 3-dimensional loading apparatus was used to cyclically apply 3 loading directions representative of physiological states at 5 progressively increasing loading magnitudes. Stemless 135° and 145° implants were compared based on the maximum implant-bone relative distraction detected, as well as the survivorship of the implants throughout the loading protocol., Results: Primary fixation and implant biomechanical survivorship were substantially better in the 145° NSA implants. The 135° NSA implants elicited significantly higher implant-bone distractions during cyclical loading ( P  = .001), and implant survivorship was considerably lower in the 135° NSA specimens when compared to the 145° NSA specimens (135° NSA: 0%, 145° NSA: 50%) ( P  < .001)., Conclusion: NSA is a modifiable parameter that influences time-zero implant stability, as well as the early survivorship of the stemless RSA humeral components tested in this study. NSA resections of 145° appear to promote better stability than those utilizing 135° NSAs during early postoperative eccentric loads. Further studies are required to assess if other stemless reversed humeral implant designs have improved time-zero fixation at higher NSAs., (© 2024 The Author(s).)

Background: The Latarjet procedure is an effective shoulder stabilizing surgery, however, the procedure results in an alteration of anatomy that may result in shoulder and elbow weakness. Thus, the purpose of this study was to assess post-operative shoulder and elbow strength after the Latarjet procedure. We hypothesized that shoulder and elbow strength are not affected after the procedure., Methods: The study group consisted of patients that had undergone the arthroscopic Latarjet procedure. An isokinetic dynamometer was used to evaluate the strength of bilateral shoulder internal rotation, elbow flexion, forearm supination using peak torque (N/m), as well as grip strength (kilograms). Shoulder range of motion and the potential effects of hand dominance were further analysed., Results: Nineteen patients with a mean age of 29 years and an average follow up of 47 months were included. Shoulder internal rotation strength, elbow flexion and forearm supination strength and grip strength were not significantly different when compared to the non-operative side ( p  > 0.13). The range of shoulder external rotation was significantly reduced ( p  < 0.001) on the Latarjet side., Conclusion: The results from this study demonstrate no statistically significant differences in the strength of shoulder internal rotation, elbow flexion, forearm supination or grip strength despite the surgical alterations to the subscapularis and conjoint tendon., Competing Interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2023.)

The treatment of proximal humerus fractures remains controversial. Although treatment modalities may vary, the goal of obtaining the best outcomes for patients remains the same. Most proximal humerus fractures can be treated nonsurgically but should still be managed actively. Deciding on surgical management requires a good understanding of indications and options. Indications for open reduction and internal fixation include younger or active patients with displaced two-, three-, and four-part fractures as well as fracture-dislocations with head-split patterns. Obtaining ideal outcomes requires anatomic reduction with restoration of the medial calcar as well as optimal position of implants to favor biomechanical stability. Reverse total shoulder arthroplasty is indicated for patients with severe and displaced fractures in older or low-demand patients. Obtaining the best functional outcomes depends on implant position, tuberosity healing, and early surgical intervention. Regardless of the treatment modality, these fractures can be challenging, and proper patient rehabilitation must be implemented. Future research will focus on patient selection and improving surgical techniques to maximize outcomes.

Background: Stemless anatomic humeral components are commonly used and are an accepted alternative to traditional stemmed implants in patients with good bone quality. Presently, little literature exists on the design and implantation parameters that influence primary time-zero fixation of stemless reverse humeral implants. Accordingly, this finite element analysis study assessed the surgical implantation variable of neck-shaft angle, and its effect on the primary time-zero fixation of reversed stemless humeral implants., Methods: Eight computed tomography-derived humeral finite element models were used to examine a generic stemless humeral implant at varying neck-shaft angles of 130°, 135°, 140°, 145°, and 150°. Four loading scenarios (30° shoulder abduction with neutral forearm rotation, 30° shoulder abduction with forearm supination, a head-height lifting motion, and a single-handed steering motion) were employed. Implantation inclinations were compared based on the maximum bone-implant interface distraction detected after loading., Results: The implant-bone distraction was greatest in the 130° neck-shaft angle implantation cases. All implant loading scenarios elicited significantly lower micromotion magnitudes when neck-shaft angle was increased (P = .0001). With every 5° increase in neck-shaft angle, there was an average 17% reduction in bone-implant distraction., Conclusions: The neck-shaft angle of implantation for a stemless reverse humeral component is a modifiable parameter that appears to influence time-zero implant stability. Lower, more varus, neck-shaft angles increase bone-implant distractions with simulated activities of daily living. It is therefore suggested that humeral head osteotomies at a higher neck-shaft angle may be beneficial to maximize stemless humeral component stability., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Introduction: Despite technological advancements in recent years, glenoid component loosening remains a common complication after anatomical total shoulder arthroplasty (ATSA) and is one of the main causes of revision surgery. Increasing emphasis is placed on the prevention of glenoid component failure. Previous studies have successfully predicted range of motion, patient-reported outcomes and short-term complications after ATSA using machine learning methods, but an accurate predictive model for (glenoid component) revision is currently lacking. This study aims to use a large international database to accurately predict aseptic loosening of the glenoid component after ATSA using machine learning algorithms., Methods and Analysis: For this multicentre, retrospective study, individual patient data will be compiled from previously published studies reporting revision of ATSA. A systematic literature search will be performed in Medline (PubMed) identifying all studies reporting outcomes of ATSA. Authors will be contacted and invited to participate in the Machine Learning Consortium by sharing their anonymised databases. All databases reporting revisions after ATSA will be included, and individual patients with a follow-up less than 2 years or a fracture as the indication for ATSA will be excluded. First, features (predictive variables) will be identified using a random forest feature selection. The resulting features from the compiled database will be used to train various machine learning algorithms (stochastic gradient boosting, random forest, support vector machine, neural network and elastic-net penalised logistic regression). The developed and validated algorithms will be evaluated across discrimination (c-statistic), calibration, the Brier score and the decision curve analysis. The best-performing algorithm will be used to create an open-access online prediction tool., Ethics and Dissemination: Data will be collected adhering to the WHO regulation on data sharing. An Institutional Review Board review is not applicable. The study results will be published in a peer-reviewed journal., Competing Interests: Competing interests: LL received consultancy fees from Depuy Stryker and royalties from Depuy-Synthes. TL received consultancy fees from Depuy Mitek and Stryker. GAB received consultancy fees from Depuy-Synthes and Stryker. The remaining authors certify that they have received no funding and have no commercial associations that might pose a conflict of interest in connection with the submitted article., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The reverse shoulder arthroplasty conceived by Paul Grammont in 1985 has gradually gained popularity as a treatment for multiple shoulder diseases. Unlike previous reverse shoulder prosthesis characterized by unsatisfactory results and a high glenoid implant failure rate, the Grammont design has immediately shown good clinical outcomes. This semi constrained prosthesis solved the issues of the very first designs by medializing and distalizing the center of rotation with an increased stability of the replacement of the component. The indication was initially limited to cuff tear arthropathy (CTA). It has then been expanded to irreparable massive cuff tears and displaced humeral head fractures. The most frequent problems of this design are a limited postoperative external rotation and scapular notching. Different modifications to the original Grammont design have been proposed with the aim of decreasing the risk of failure and complications and improving the clinical outcomes. Both the position and version/inclination of the glenosphere and the humeral configuration (e.g. neck shaft angle) influence the RSA outcomes. A lateralized glenoid (whether with bone or metal) and a 135° Inlay system configuration leads to a moment arm which is the closest to the native shoulder. Clinical research will focus on implant designs reducing bone adaptations and revision rate, strategies to prevent more effectively infections. Furthermore, there is still room for improvement in terms of better postoperative internal and external rotations and clinical outcomes after RSA implanted for humeral fracture and revision shoulder arthroplasty., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

This work developed, validated, and compared statistical shape, statistical intensity, and statistical shape and intensity models (SSMs, SIMs, SSIMs) of scapulae from a clinical population. SSMs efficiently describe bone shape variation while SIMs describe bone material property variation, and SSIM's combine description of both variables. This work establishes these models' efficacy and whether they can be used in surgical planning. Models were developed using shoulder arthroplasty data of patients with bone erosion, which is challenging to treat and would benefit from improved surgical planning. Models were created using previously validated nonrigid registration and material property assignment processes that were optimized for scapula characteristics. The models were assessed using standard metrics, anatomical measurements, and correlation analyses. The SSM and SIM specificity and generalization error metrics were 3.4 mm and <1 mm and 184 HU and 156 HU, respectively. The SSIM did not achieve the same level of performance as the SSM and SIM in this study (e.g., shape generalization: SSIM-2.2 mm versus SSM-<1 mm). Anatomical correlation analysis showed that the SSM more effectively and efficiently described shape variation compared to the SSIM. The SSM and SIM modes of variation were not strongly correlated (e.g., rmax = 0.56 for modes explaining ≤2.1% of variance). The SSIM is outperformed by the SSM and SIM and the latter two are not strongly correlated; therefore, using the SSM and SIM in conjunction will generate synthetic bone models with realistic characteristics and thus can be used for biomechanical surgical planning applications., (Copyright © 2023 by ASME.)

Objective: To investigate patient and clinician preferences regarding a preoperative educational program for patients undergoing shoulder replacement surgery., Methods: This study used a cross-sectional survey of patients awaiting shoulder replacement surgery and clinicians. The survey was comprised of 41 questions for patients and clinicians, regarding preferences for receiving information, content preferences and device preferences. Descriptive statistics were reported for survey questions., Results: 180 patients and 175 clinicians completed the survey. Patients and clinicians' top choices for ways to receive information were: in-person, website and booklets, with use of CD/DVD being extremely unlikely. Patients and clinicians had different preferences regarding content choices. Patients rated the following content topics as important to include in a program: including other patient's previous experiences with this surgery (83 % patients; 40 % clinicians), information for caregivers (84 % patients; 65 % clinicians), expectations for hospital stay (89 % patients; 57 % clinicians), process of anesthesia (87 % patients; 51 % clinicians), and how the surgery is performed (94 % patients; 60 % clinicians)., Conclusions: Clinicians and patients have differing priorities and perspectives on the content and delivery of preoperative education programs, however, therapeutic goals and accessibility should be considered when designing programs., Practice Implications: Creating education programs should include the lens of both clinicians and patients., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Heterotopic ossification is a frequent complication following surgical treatment of elbow trauma. The use of indomethacin to prevent heterotopic ossification is reported in the literature; however, its effectiveness is controversial. The purpose of this randomized, double-blind, placebo-controlled study was to determine whether indomethacin is effective in reducing the incidence and severity of heterotopic ossification after surgical management of elbow trauma., Methods: Between February 2013 and April 2018, 164 eligible patients were randomized to receive postoperative indomethacin or placebo medication. The primary outcome was the incidence of heterotopic ossification on elbow radiographs at 1-year follow-up. Secondary outcomes included the Patient Rated Elbow Evaluation score, Mayo Elbow Performance Index score, and Disabilities of the Arm, Shoulder and Hand score. Range of motion, complications, and nonunion rates were also obtained., Results: At 1-year follow-up, there was no significant difference in the incidence of heterotopic ossification between the indomethacin group (49%) and the control group (55%) (relative risk, 0.89; P = .52). There were no significant differences in postoperative Patient Rated Elbow Evaluation, Mayo Elbow Performance Index, and Disabilities of the Arm, Shoulder and Hand scores or range of motion (P = .16). The complication rate was 17% in both the treatment and control groups (P > .99). There were no nonunions in either group., Conclusion: This Level I study demonstrated that indomethacin prophylaxis against heterotopic ossification in the setting of surgically treated elbow trauma was not significantly different from placebo., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Preoperative traditional software planning (TSP) is a method used to assist surgeons with implant selection and glenoid guide-pin insertion in shoulder arthroplasty. Mixed-Reality (MR) is a new technology that uses digital holograms of the preoperative plan and guide-pin trajectory projected into the operative field. The purpose of this study was to compare TSP to MR in a simulated surgical environment involving insertion of guide-pins into models of severely deformed glenoids., Methods: Eight surgeons inserted guide-pins into eight randomized three-dimensional-printed severely eroded glenoid models in a simulated surgical environment using either TSP or MR. In total, 128 glenoid models were used and statistically compared. The outcomes compared between techniques included procedural time, difference in guide-pin start point, difference in version and inclination, and surgeon confidence via a confidence rating scale., Results: When comparing traditional preoperative software planning to MR visualization as techniques to assist surgeons in glenoid guide pin insertion, there were no statistically significant differences in terms of mean procedure time (P=0.634), glenoid start-point (TSP = 2.2 ± 0.2 mm , MR = 2.1 ± 0.1 mm; P=0.760), guide-pin orientation (P=0.586), or confidence rating score (P=0.850)., Conclusions: The results demonstrate that there were no significant differences between traditional preoperative software planning and MR visualization for guide-pin placement into models of eroded glenoids. A perceived benefit of MR is the real-time intraoperative visibility of the surgical plan and the patient's anatomy; however, this did not translate into decreased procedural time or improved guide-pin position. Level of evidence: Basic Science Study; Biomechanics.

The objective of this structured review was to review how computed tomography (CT) scanning has been used to measure the kinematics of the shoulder. A literature search was conducted using Evidence-based Medicine Reviews (Embase) and PubMed. In total, 29 articles were included in the data extraction process. Forty percent of the studies evaluated healthy participants' shoulder kinematics. The glenohumeral joint was the most studied, followed by the scapulothoracic, acromioclavicular, and sternoclavicular joints. Three-dimensional computed tomography (3DCT) and 3DCT with biplane fluoroscopy are the two primary imaging techniques that have been used to measure shoulder joints' motion under different conditions. Finally, many discrepancies in the reporting of the examined motions were found. Different authors used different perspectives and planes to report similar motions, which results in confusion and misunderstanding of the actual examined motion. The use of 3DCT has been widely used in the examination of shoulder kinematics in a variety of populations with varying methods employed. Future work is needed to extend these methodologies to include more diverse populations, to examine the shoulder complex as a whole, and to standardize their reporting of motion examined to make study to study comparisons possible., (© 2023. International Federation for Medical and Biological Engineering.)

Purpose: To determine the return-to-sport rate following arthroscopic Bankart repair with remplissage (ABR), including overall rate of return to sport, rate of return to preinjury level of sport, and the rate of return for specific subgroups such as contact or throwing athletes., Methods: EMBASE, PubMed, and MEDLINE were searched from database inception until February 2022. Studies were screened by 2 reviewers independently and in duplicate for data regarding rates of return to sport following ABR. Data on return to sport and functional outcomes were recorded. Data are presented in a descriptive fashion., Results: Overall, 20 studies were included with a total of 736 patients (738 shoulders) who underwent ABR. These patients had a mean age of 28 years (range 14-72 years) and were 83% male. Mean follow-up time after surgery was 45 months (range 12-127 months). The rate of return to any level of sport ranged from 60% to 100%, whereas the rate of return to the preinjury level ranged from 63% to 100%. When we excluded those who underwent ABR as a revision procedure, the rate of return to any level of sport was 68% to 100%. Lastly, the return to sport rates for contact or collision athletes ranged from 80% to 100%, whereas for overhead or throwing athletes it was 46% to 79%. The rate of recurrence of instability postoperatively ranged from 0% to 20% in included studies., Conclusions: For athletes with anterior shoulder instability, ABR led to a high rate of return to sport along with a low rate of recurrence of instability. Although most athletes are able to return to the same level of sport, certain groups such as throwing athletes may face greater difficulty., Level of Evidence: Level IV, systematic review of Level III and IV studies., (Copyright © 2023 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Postoperative periprosthetic humeral shaft fractures represent a growing and difficult complication to treat given the aging patient population and associated bone loss. Determining the best treatment option is multifactorial, including patient characteristics, fracture pattern, remaining bone stock, and implant stability. Possible treatment options include nonoperative management with bracing or surgical intervention. Nonoperative treatment has been shown to have higher nonunion rates, thus should only be selected for a specific patient population with minimally displaced fractures or those that are unfit for surgery. Surgical management is recommended with prosthetic loosening, fracture nonunion, or failure of nonoperative treatment. Surgical options include open reduction and internal fixation, revision arthroplasty, or hybrid fixation. Careful evaluation, decision making, and planning is required in the treatment of these fractures., (Copyright © 2023 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Orthopaedic Trauma Association.)

Introduction: The effectiveness of rotator cuff tear repair surgery is influenced by multiple patient-related, pathology-centred and technical factors, which is thought to contribute to the reported retear rates between 17% and 94%. Adequate patient selection is thought to be essential in reaching satisfactory results. However, no clear consensus has been reached on which factors are most predictive of successful surgery. A clinical decision tool that encompassed all aspects is still to be made. Artificial intelligence (AI) and machine learning algorithms use complex self-learning models that can be used to make patient-specific decision-making tools. The aim of this study is to develop and train an algorithm that can be used as an online available clinical prediction tool, to predict the risk of retear in patients undergoing rotator cuff repair., Methods and Analysis: This is a retrospective, multicentre, cohort study using pooled individual patient data from multiple studies of patients who have undergone rotator cuff repair and were evaluated by advanced imaging for healing at a minimum of 6 months after surgery. This study consists of two parts. Part one: collecting all potential factors that might influence retear risks from retrospective multicentre data, aiming to include more than 1000 patients worldwide. Part two: combining all influencing factors into a model that can clinically be used as a prediction tool using machine learning., Ethics and Dissemination: For safe multicentre data exchange and analysis, our Machine Learning Consortium adheres to the WHO regulation 'Policy on Use and Sharing of Data Collected by WHO in Member States Outside the Context of Public Health Emergencies'. The study results will be disseminated through publication in a peer-reviewed journal. Institutional Review Board approval does not apply to the current study protocol., Competing Interests: Competing interests: AL is a paid consultant for Arthrex, Medacta and Stryker. He receives royalties from Stryker. He is the founder of BeeMed, Med4Cast and FORE. He owns stock options from Medacta. LL is a consultant for Depuy Stryker, received royalties from Depuy. TL is consultant for Depuy Mitek and Stryker. GAB received consultancy fees from Depuy-Synthes and Research Funds from SECEC, Vivalto Santé. The remaining authors certify that neither he or she has funding or commercial associations that might pose a conflict of interest in connection with the submitted article., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Finite element analysis has suggested that stemless implants may theoretically decrease stress shielding. The purpose of this study was to assess the radiographic proximal humeral bone adaptations seen following stemless anatomic total shoulder arthroplasty., Methods: A retrospective review of 152 prospectively followed stemless total shoulder arthroplasty utilizing a single implant design was performed. Anteroposterior and lateral radiographs were reviewed at standard time points. Stress shielding was graded as mild, moderate, and severe. The effect of stress shielding on clinical and functional outcomes was assessed. Also, the influence of subscapularis management on the occurrence of stress shielding was determined., Results: At 2 years postoperatively, stress shielding was noted in 61 (41%) shoulders. A total of 11 (7%) shoulders demonstrated severe stress shielding with 6 occurring along the medial calcar. There was one instance of greater tuberosity resorption. At the final follow-up, no humeral implants were radiographically loose or migrated. There was no statistically significant difference in clinical and functional outcomes between shoulders with and without stress shielding. Patients undergoing a lesser tuberosity osteotomy had lower rates of stress shielding, which was statistically significant ( p  = 0.021)., Discussion: Stress shielding does occur at higher rates than anticipated following stemless total shoulder arthroplasty, but was not associated with implant migration or failure at 2 years follow-up., Level of Evidence: IV, Case series., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2021.)

Background: In a simple isolated capitellar/trochlear fracture without extensive posterior comminution, arthroscopic reduction and internal fixation (ARIF) can provide an alternative option to open reduction internal fixation. The purpose of this retrospective case series was to report on the technique and outcomes of arthroscopic reduction and internal fixation of capitellar/trochlear fractures., Methods: All patients that underwent ARIF at a single upper extremity referral centre in the last twenty years were reviewed. Patient demographics, preoperative, intraoperative, and postoperative records were obtained through chart review and telephone followup., Results: Ten cases of ARIF were identified over a twenty year period performed by two surgeons. The average age of patients was 37 years (17-63 years), with nine females and one male. With an average followup of eight years, nine of ten patients had a mean range of motion from 0 to 142 degrees. Their average MEPI and PREE score were 93 ± 7 and 8 ± 14, respectively. Four patients had focal cartilage collapse with three that required a reoperation. There were no infections, nonunions, or arthroscopy related complications., Conclusion: ARIF offers an alternative to ORIF for capitellar/trochlear fractures producing good results while providing better visualization of the fracture reduction and minimizing soft tissue dissection., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2021.)

Purpose: This study aimed to assess the accuracy and reproducibility of four common segmentation techniques measuring subchondral bone cyst volume in clinical-CT scans of glenohumeral OA patients., Methods: Ten humeral head osteotomies collected from cystic OA patients, having undergone total shoulder arthroplasty, were scanned within a micro-CT scanner, and corresponding preoperative clinical-CT scans were gathered. Cyst volumes were measured manually in micro-CT and served as a reference standard (n = 13). Respective cyst volumes were measured on the clinical-CT scans by two independent graders using four segmentation techniques: Qualitative, Edge Detection, Region Growing, and Thresholding. Cyst volume measured in micro-CT was compared to the different clinical-CT techniques using linear regression and Bland-Altman analysis. Reproducibility of each technique was assessed using intraclass correlation coefficient (ICC)., Results: Each technique outputted lower volumes on average than the reference standard (-0.24 to -3.99 mm 3 ). All linear regression slopes and intercepts were not significantly different than 1 and 0, respectively (p < 0.05). Cyst volumes measured using Qualitative and Edge Detection techniques had the highest overall agreement with reference micro-CT volumes (mean discrepancy: 0.24, 0.92 mm 3 ). These techniques showed good to excellent reproducibility between graders., Conclusions: Qualitative and Edge Detection techniques were found to accurately and reproducibly measure subchondral cyst volume in clinical-CT. These findings provide evidence that clinical-CT may accurately gauge glenohumeral cystic presence, which may be useful for disease monitoring and preoperative planning., Level of Evidence: Retrospective cohort Level 3 study., (© 2023. The Author(s).)

Background: Several techniques have been described for mobilizing the subscapularis tendon in anatomic total shoulder arthroplasty (TSA). The purpose of this study was to compare subscapularis tendon healing rates, as determined by ultrasound, in patients following anatomic TSA with either a subscapularis tenotomy or subscapularis peel., Methods: This study was a secondary analysis of patients from a previous randomized controlled trial in which patients underwent anatomic TSA and were randomized to either a tenotomy or peel approach. The primary outcome was postoperative tendon healing rates determined on ultrasound at >12 months after surgery. Secondary outcomes included postoperative tendon thickness measured on ultrasound; elbow position (neutral alignment in the belly-press position vs. posterior); internal rotation function measured with the third and fourth questions of the American Shoulder and Elbow Surgeons questionnaire; and Western Ontario Osteoarthritis of the Shoulder index. Radiographs were analyzed in patients with torn tendons., Results: One hundred patients were randomized to a tenotomy (n = 47) or peel (n = 53) approach. Postoperative ultrasound results were available in 88 patients. Tendon healing rates were 95% for tenotomy vs. 75% for peel (P = .011). The mean postoperative tendon thickness was 4 mm (standard deviation, 1.0 mm) and 4 mm (standard deviation, 1 mm) in the tenotomy and peel groups, respectively (P = .37). Internal rotation function was not associated with healing status (P = .77 and P = .22 for questions 3 and 4, respectively, of the American Shoulder and Elbow Surgeons questionnaire), nor was elbow position (P = .2) in the belly-press position., Discussion: We observed that subscapularis tenotomy had a higher healing rate than peel as determined by ultrasound in TSA patients. There was no statistically significant difference in postoperative tendon thickness in intact tendons as measured on ultrasound when comparing subscapularis mobilization techniques, nor was there any association between healing status and internal rotation function or elbow position., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: A transverse force couple (TFC) functional imbalance has been demonstrated in osteoarthritic shoulders by recent 3-dimensional (3D) muscle volumetric studies. Altered rotator cuff vectors may be an additional factor contributing to a muscle imbalance and the propagation of glenoid deformity., Methods: Computed tomography images of 33 Walch type A and 60 Walch type B shoulders were evaluated. The 3D volumes of the entire subscapularis, supraspinatus, and infraspinatus-teres minor (ISP-Tm) and scapula were manually segmented. The volume masks and scapular landmarks were imported into MATLAB to create a coordinate system, enabling calculation of muscle force vectors. The direction of each muscle force vector was described in the transverse and vertical plane, calculated with respect to the glenoid. Each muscle vector was then resolved into compression and shear force across the glenoid face. The relationship between muscle force vectors, glenoid retroversion or inclination, compression/shear forces on the glenoid, and Walch type was determined using linear regression., Results: In the transverse plane with all rotator cuff muscles combined, increasing retroversion was significantly associated with increasing posterior drag (P < .001). Type B glenoids had significantly more posterior drag than type A (P < .001). In the vertical plane for each individual muscle group and in combination, superior drag increases as superior inclination increases (P < .001). Analysis of individual muscle groups showed that the anterior thrust of ISP-Tm and supraspinatus switched to a posterior drag at 8° and 10° of retroversion respectively. The compression force on the glenoid face by ISP-Tm and supraspinatus did not change with increasing retroversion for type A shoulders (P = .592 and P = .715, respectively), but they did for type B shoulders (P < .001 for both). The glenoid shear force ratio in the transverse plane for the ISP-Tm and supraspinatus moved from anterior to posterior shear with increasing glenoid retroversion, crossing zero at 8° and 10° of retroversion, whereas the subscapularis exerted a posterior shear force for every retroversion angle., Conclusion: Increased glenoid retroversion is associated with increased posterior shear and decreased compression forces on the glenoid face, explaining some of the pathognomonic bone morphometrics that characterize the osteoarthritic shoulder. Although the subscapularis always maintains a posterior thrust, the ISP-Tm and supraspinatus together showed an inflection at 8° and 10° of retroversion, changing from an anterior thrust to a posterior drag. This finding highlights the importance that in anatomic TSA the rotator cuff functional balance might be better restored by correcting glenoid retroversion to less than 8°., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

The increased utilization of shoulder arthroplasty, including revision procedures, combined with rises in life expectancy, is expected to translate into a substantial increase in periprosthetic humeral fractures. The evaluation and management of these fractures needs to be updated to consider fractures that complicate anatomic and reverse arthroplasties and contemporary short-stem and stemless implants. Although conservative treatment is successful in a large proportion of these fractures, several surgical reconstructive techniques are required for the management of all fracture types. Surgical options include internal fixation, graft augmentation, standard revision procedures, and occasionally complex reconstructions including modular segmental prosthesis and allograft prosthetic composites. Most studies on the outcomes of periprosthetic humeral fractures have analyzed small samples and have typically reported on anatomic total shoulders with a standard-length humeral implant. Additional research is required to optimize the management of periprosthetic postoperative humeral fractures in the era of reverse arthroplasty, short stems, and stemless arthroplasty., (Copyright © 2022 by the American Academy of Orthopaedic Surgeons.)

Introduction: Shoulder instability is a common injury, with a reported incidence of 23.9 per 100 000 person-years. There is still an ongoing debate on the most effective treatment strategy. Non-operative treatment has recurrence rates of up to 60%, whereas operative treatments such as the Bankart repair and bone block procedures show lower recurrence rates (16% and 2%, respectively) but higher complication rates (<2% and up to 30%, respectively). Methods to determine risk of recurrence have been developed; however, patient-specific decision-making tools are still lacking. Artificial intelligence and machine learning algorithms use self-learning complex models that can be used to make patient-specific decision-making tools. The aim of the current study is to develop and train a machine learning algorithm to create a prediction model to be used in clinical practice-as an online prediction tool-to estimate recurrence rates following a Bankart repair., Methods and Analysis: This is a multicentre retrospective cohort study. Patients with traumatic anterior shoulder dislocations that were treated with an arthroscopic Bankart repair without remplissage will be included. This study includes two parts. Part 1, collecting all potential factors influencing the recurrence rate following an arthroscopic Bankart repair in patients using multicentre data, aiming to include data from >1000 patients worldwide. Part 2, the multicentre data will be re-evaluated (and where applicable complemented) using machine learning algorithms to predict outcomes. Recurrence will be the primary outcome measure., Ethics and Dissemination: For safe multicentre data exchange and analysis, our Machine Learning Consortium adhered to the WHO regulation 'Policy on Use and Sharing of Data Collected by WHO in Member States Outside the Context of Public Health Emergencies'. The study results will be disseminated through publication in a peer-reviewed journal. No Institutional Review Board is required for this study., Competing Interests: Competing interests: GSA reports as ‘financial activities outside the submitted work’ to be a consultant for ConMed Linvatec. LL is a consultant for Depuy Stryker, received royalties from Depuy. TL is consultant for Depuy Mitek and Stryker. GAB received consultancy fees from Depuy-Synthes and Research Funds from SECEC, Vivalto Santé. The remaining authors certify that neither he or she has funding or commercial associations that might pose a conflict of interest in connection with the submitted article., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Glenoid bone loss is one of the main challenges in revision of failed shoulder arthroplasties. The concept of a hemi-reverse procedure is to implant a glenoid baseplate and glenosphere to protect the glenoid reconstruction to allow it to heal and to preserve the joint space for a potential second-stage humeral component implantation. The purpose of this study was to report the results of hemi-reverse procedures., Methods: Revision to a hemi-reverse procedure was performed in 15 patients: 8 with a failed anatomic total shoulder arthroplasty, 3 with a failed reverse shoulder arthroplasty, 3 with a failed humeral hemiarthroplasty, and 1 with placement of a cement spacer owing to sepsis after a total shoulder arthroplasty. After complete removal of the initial prosthesis, all patients underwent glenoid reconstruction with bone grafting and implantation of a reverse arthroplasty baseplate and glenosphere. A humeral implant was not placed in any case. The patients were prospectively followed up and underwent complete clinical and radiologic studies preoperatively and postoperatively at a minimum of 2 years after the surgical procedure., Results: Thirteen hemi-reverse implants and glenoid bone grafts healed (86%) and remained radiographically stable. One hemi-reverse construct migrated and became mechanically loose, which was attributed to absent fixation of the central post in the native glenoid bone. In 1 patient, an implant-related infection developed; irrigation and debridement were performed, in addition to revision to a resection arthroplasty. After documented radiographic healing of the hemi-reverse glenoid reconstruction, 5 patients underwent a second-stage revision to a reverse procedure with insertion of a humeral component at a median of 6 months (interquartile range [IQR], 6-8 months). In this group, the median follow-up period was 73 months (IQR, 45-153 months), the median Constant score was 48 (IQR, 41-56), median active forward elevation was 135° (IQR, 100°-150°), and the median Subjective Shoulder Value was 50% (IQR, 50%-60%). In the group of 9 patients with remaining hemi-reverse implants, the median follow-up period was 38 months (IQR, 29-60 months), the median Constant score was 41 (IQR, 38-46), median active forward elevation was 100° (IQR, 80°-100°), and the median Subjective Shoulder Value was 50% (IQR, 40%-60%)., Conclusion: The hemi-reverse procedure is an effective revision procedure to reconstruct a severely deficient glenoid. The hemi-reverse procedure may function as the definitive procedure, with satisfactory outcomes. Additionally, in patients who undergo the hemi-reverse procedure, second-stage revision to a total reverse procedure can be performed once imaging confirms bone graft and construct stability., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.)

Subchondral trabecular bone (STB) undergoes adaptive changes during osteoarthritic (OA) disease progression. These changes alter both the mineralization patterns and structure of bone and may contribute to variations in the mechanical properties. Similarly, when images are downsampled - as is often performed in micro finite element model (microFEM) generation - the morphological and mineralization patterns may further alter the mechanical properties due to partial volume effects. MicroFEMs accounting for material heterogeneity can account for these tissue variations, but no studies have validated these with robust full-field testing methods. As such, this study compared homogeneous and heterogeneous microFEMs to experimentally loaded trabecular bone cores from the humeral head combined with digital volume correlation (DVC). These microFEMs were used to compare apparent mechanical properties between normal and OA STB. Morphological and mineralization patterns between groups were also compared. There were no significant differences in tissue or bone mineral density between groups. The only significant differences in morphometric parameters were in trabecular thickness between groups. There were no significant differences in linear regression parameters between normal and OA STB apparent mechanical properties estimated using heterogeneous microFEMs with an element-wise bilinear elastic-plastic constitutive model. Clinical significance: Validated heterogeneous microFEMs applied to STB of the humeral head have the potential to significantly improve our understanding of mechanical variations in the bone that occur during OA progression., (© 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)