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Background: The ABC classification has recently been proposed as a comprehensive classification system for posterior shoulder instability (PSI). The purpose of this study was to analyze the comprehensiveness as well as inter-rater and intrarater reliability of the ABC classification., Methods: All consecutive patients presenting with unidirectional PSI from June 2019 to June 2021 were included in a prospective study. No patients were excluded, leaving a consecutive series of 100 cases of PSI in 91 patients. All recorded clinical and imaging data were used to create anonymized clinical case vignettes, which were evaluated twice according to the ABC classification at the end of the recruitment period in random sequential order by 4 independent raters (2 experienced shoulder surgeons and 2 orthopedic residents) to analyze the comprehensiveness as well as inter-rater and intrarater reliability of the ABC classification for PSI and to describe differences in characteristics among subtypes. Group A was defined as a first-time singular PSI event <3 months in the past regardless of etiology and is further subdivided into type 1 and type 2 depending on the occurrence of a subluxation (A1) or dislocation (A2). Group B comprises recurrent dynamic PSI regardless of time since onset and is further subdivided by the cause of instability into functional (B1) and structural (B2) dynamic PSI. Group C includes chronic static PSI with posterior humeral decentering that can be either constitutional (C1) or acquired (C2)., Results: None of the cases was deemed unsuitable to be classified based on the proposed system by the observers. After consensus agreement between the 2 expert raters, 16 cases were attributed to group A (8 type A1 and 8 type A2); 64, to group B (33 type B1 and 31 type B2); and 20, to group C (11 type C1 and 9 type C2). The expert raters agreed on the classification subtypes in 99% and 96% of the cases during the first rating and second rating, respectively (intraclass correlation coefficients [ICCs], 0.998 and 0.99, respectively). The intraobserver reliability was excellent for both raters. The beginners reached the same conclusion as the consensus agreement in 94% of the cases (ICC, 0.99) and 89% of the cases (ICC, 0.97) during the first round and 94% each (ICC, 0.97) during the second round. The intraobserver reliability was excellent for both beginners. Overall, discrepancies between raters were found between groups B1 and B2 (n = 14), groups B2 and C2 (n = 4), groups B1 and C1 (n = 1), and groups A1 and B2 (n = 1). In general, each subtype showed distinctive clinical and imaging characteristics that facilitated the diagnosis., Conclusion: The presented ABC classification for PSI is a comprehensive classification with a high reliability and reproducibility. However, a gradual transition and potential progression between the subtypes of PSI must be considered. The reliable distinction between different subtypes of PSI based on etiology and pathomechanism provides a standardized basis for future investigations on treatment recommendations., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Implementation of a system anchored in patient outcomes is challenged to gain widespread adoption required to demonstrate the value of care provided for shoulder conditions. This is in large part because of the administrative burden created by current tools and clinical implementation barriers that limit practical use and therefore leave most clinicians, administrators, payers, and patients without a measure of what matters most: Are patients improving? Thus, we must ask ourselves, How do we accurately and efficiently measure and report quality of care in a simple, reliable, and easily communicated manner? We propose that the Single Assessment Numeric Evaluation (SANE) score is the best solution to measure patient improvement and can be used universally for all shoulder conditions. The measure is simple, valid, reliable, and sensitive to change and has the lowest implementation barrier compared with all other outcome measures., Methods: We synthesized the available literature (11 studies) that demonstrates strong psychometrics comparable to legacy measures across >4000 patients with a wide range of shoulder conditions., Results: SANE scores range from 40% to 60% at baseline for most patients before treatment and range from 75% to 85% at 1 year after therapy depending on the condition, similar to legacy scores such as the American Shoulder and Elbow Surgeons score. Additionally, the SANE score shows similar baseline and post-care measures across conditions that can be used to guide clinical care. This finding shows that the observed baseline and improvement scores can provide valuable patient assessment and can be used in aggregate for quality improvement and other value-based purposes., Conclusion: We strongly recommend the SANE score as the primary patient outcome measure for patients with all shoulder conditions, given the value of measuring every patient's progress and growing pressure to quantify patient outcomes., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Preoperative teres minor insufficiency has been identified as a risk factor for poor restoration of external rotation (ER) after reverse total shoulder arthroplasty (RTSA). However, there has been little investigation regarding muscle activation patterns generating ER. This prospective study sought to determine the timing and activation levels of the shoulder girdle musculature during ER in well-functioning RTSAs with an intact teres minor using a lateralized design., Methods: Patients who underwent RTSA ≥1 year previously with functional ER, an American Shoulder and Elbow Surgeons (ASES) score >70, superior rotator cuff deficiency, and an intact teres minor were identified. Electrophysiological and kinematic analyses were performed during ER in the modified neutral position (arm at side with 90° of elbow flexion) and in abduction (AB) (shoulder abducted 90° with 90° of elbow flexion). Dynamometer-recorded torque and position were pattern matched to electromyography during ER. The root-mean-square and integrated electromyography (in microvolts × milliseconds with standard deviation [SD]), as well as median frequency (MF) (in hertz with SD), were calculated to determine muscle recruitment. Pair-wise t test analysis compared muscle activation (P < .05 indicated significance)., Results: After an a priori power analysis, 16 patients were recruited. The average ASES score, visual analog scale pain score, and ASES subscore for ER in AB ("comb hair") were 87.7, 0.5, and 2.75 of 3, respectively. In AB, muscle activation began with the upper trapezius, middle trapezius, and latissimus dorsi, followed by the anterior deltoid activating to neutral. With ER beyond neutral, the teres major (9.6 μV × ms; SD, 9.2 μV × ms) initiated ER, followed by the teres minor (14.1 μV × ms; SD, 18.2 μV × ms) and posterior deltoid (11.1 μV × ms; SD, 9.3 μV × ms). MF analysis indicated equal contributions of the teres major (1.1 Hz; SD, 0.5 Hz), teres minor (1.2 Hz; SD, 0.4 Hz), and posterior deltoid (1.1 Hz; SD, 0.4 Hz) in ER beyond neutral. In the modified neutral position, the upper trapezius and middle trapezius were not recruited to the same level as in AB. For ER beyond neutral, the teres major (9.5 μV × ms [SD, 9 μV × ms]; MF, 1.1 Hz [SD, 0.5 Hz]), teres minor (11.4 μV × ms [SD, 15.1 μV × ms]; MF, 1.1 Hz [SD, 0.5 Hz]), and posterior deltoid (8.5 μV × ms [SD, 8 μV × ms]; MF, 1.2 Hz [SD, 0.3 Hz]) were activated in similar sequence and intensity as AB. No differences in muscle activation duration or intensity were noted among the teres major, teres minor, and posterior deltoid (P > .05)., Conclusion: Active ER after RTSA is complex and is not governed by a single muscle-tendon unit. This study establishes a sequence, duration, and intensity of muscle activation for ER in well-functioning RTSAs. In both tested positions, the teres major, teres minor, and posterior deltoid function equally and sequentially to power ER., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

The shoulder joint complex in the overhead athlete is organized to effectively transfer the proximally generated forces distally into the arm. The organization also protects the joints and anatomic structures against the repetitive high velocities, large ranges of motions, and compressive, shear, translational, and distraction loads in the overhead motion while placing the hand in the "launch window." Coupling of the movements of the scapula, clavicle, and humerus results in scapulohumeral rhythm (SHR). Effective SHR requires the clavicle and scapula-and, at times, the mechanically linked claviscapular segment-to move the arm into the task-specific position and motion and requires the humerus to move through the ranges of motion to achieve the specific task in the throwing motion. Alterations in SHR can negatively affect effective shoulder joint complex function in the overhead throwing motion and increase injury risk. There are 4 phases of clavicular, scapular, and claviscapular motion that are coupled with arm motion in SHR. The first 3 phases occur in arm elevation motions from 0°-90° and result in the claviscapula and humerus being placed in task-specific positions. The fourth phase is coupling of claviscapular motion with humeral motion to maintain ball-and-socket kinematics throughout the throwing motion. Alterations in this composite motion are termed "scapular dyskinesis." The dyskinesis is considered an impairment of the efficient mobility of the claviscapular segment of the shoulder complex. The most prevalent problem with scapular dyskinesis is the association of scapular protraction and consequent glenoid antetilt with alterations in humeral rotation and posterior humeral head translation to produce shoulder joint internal impingement. Task effectiveness in overhead throwing is also based on and determined by humeral range of motion, precision of humeral motion, and velocity of humeral motion, as well as humeral and arm position in 3-dimensional space. This activity requires maximum ball-and-socket kinematics to create the highest amount of concavity-compression that creates stability for the joint. There are bony and soft-tissue contributions to this stability. Injuries to the glenoid labrum are among the most common deficits that alter concavity-compression. Clinical evaluation of the shoulder joint complex in the injured throwing athlete should be comprehensive and systematic, following an evaluation pathway for proximal and distal causative factors and including observation of humeral motion. This type of evaluation can result in intervention protocols that address the pathoanatomic, pathophysiological, and pathomechanical deficits identified., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Proper proprioceptive and neuromuscular control is crucial for the overhead athlete's performance. The aim of the present study was to evaluate the shoulder joint position sense (JPS) levels in overhead throwing athletes. The secondary aim was to confront the proprioceptive abilities with glenohumeral adaptive changes and pathologies among athletes., Methods: Ninety professional handball players and 32 healthy volunteers were recruited. JPS levels were measured by an electronic goniometer and expressed as values of an active reproduction of the joint position (ARJP) and as error of ARJP (EARJP) in 3 different reference positions for each movement (abduction and flexion at 60°, 90°, and 120°; internal [IR] and external rotation [ER] at 30°, 45°, and 60°)., Results: Side-to-side differences revealed significantly better values of EARJP for the throwing shoulders in abduction at 90° and 120°, flexion at 90° and 120°, IR at 60°, and ER at 30° and 60° compared with the nonthrowing shoulders. Handball players showed significantly better proprioceptive levels in their throwing shoulder compared to the dominant shoulder of the control group in abduction at 90° (P = .037) and 120° (P = .001), flexion at 120° (P = .035), IR at 60° (P = .045), and in ER at 60° (P = .012)., Discussion: Handball players present superior shoulder JPS in their dominant throwing shoulder at high range of motion angles when compared to a nonathlete population and to their own nondominant shoulder., (Copyright © 2023. Published by Elsevier Inc.)

Background: There is no agreement on the best choice of proximal humeral reconstruction following tumor resection in pediatric patients. We reviewed the functional outcomes, oncologic outcomes, and surgical complications in pediatric patients after proximal humeral reconstruction with cemented osteoarticular allograft., Methods: Eighteen patients aged 8-13 years who underwent proximal humeral osteoarticular allograft reconstruction following resection of primary bone sarcoma were included. The mean follow-up period was 88 ± 31.7 months. At the last follow-up assessment, limb function was evaluated based on shoulder range of motion, Musculoskeletal Tumor Society score, and Toronto Extremity Salvage Score. Tumor recurrence and postoperative complications were extracted from the patients' medical records., Results: Mean active forward flexion of the shoulder was 38° ± 18°. Mean active abduction was 48° ± 18°. Mean active external rotation was 23° ± 9°. The mean Musculoskeletal Tumor Society score was 73.4% ± 11.2%. The mean Toronto Extremity Salvage Score was 75.6% ± 12.9%. Local recurrence occurred in 1 patient. Metastasis developed after the operation in 2 additional patients. We recorded 6 postoperative complications in this series, including 1 superficial infection, 1 late-onset deep infection, 1 allograft fracture, 2 cases of nonunion, and 2 cases of shoulder instability. Two complications required allograft removal., Conclusion: In pediatric patients, reconstruction of the proximal humerus with cemented osteoarticular allograft results in acceptable oncologic and functional outcomes while the postoperative complication rate seems to be lower than that of other available techniques., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Obesity influences the outcomes of orthopedic surgeries such as total knee arthroplasty and spinal surgery. However, the effect of obesity on the outcomes of rotator cuff repair is unknown. This systematic review and meta-analysis aimed to examine the effect of obesity on rotator cuff repair outcomes., Methods: PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched to identify relevant studies published from their inception till July 2022. Two reviewers independently screened titles and abstracts using the specified criteria. Articles were included if they indicated the effect of obesity on rotator cuff repair and the related outcomes after surgery. Review Manager 5.4.1 software was used to perform statistical analysis., Results: Thirteen articles involving 85,497 patients were included. Obese patients had higher retear rates than nonobese patients (odds ratio [OR] 2.58, 95% confidence interval [CI] 1.23-5.41, P = .01), lower American Shoulder and Elbow Surgeons scores (mean difference [MD]: -3.59, 95% CI: -5.45 to [-1.74]; P = .0001), higher visual analog scale for pain (mean difference: 0.73, 95% CI: 0.29-1.17; P = .001), higher reoperation rates (OR 1.31, 95% CI 1.21-1.42, P < .00001), and higher rates of complications (OR 1.57, 95% CI 1.31-1.87, P = .000). Obesity did not affect the duration of surgery (MD: 6.03, 95% CI: -7.63 to 19.69; P = .39) or external rotation of the shoulder (MD: -1.79, 95% CI: -5.30 to 1.72; P = .32)., Conclusion: Obesity is a significant risk factor for retear and reoperation after rotator cuff repair. Furthermore, obesity increases the risk of postoperative complications and leads to lower postoperative American Shoulder and Elbow Surgeons scores and higher shoulder visual analog scale for pain., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Primary idiopathic adhesive capsulitis (AC) is characterized by shoulder pain and global limitations in range of motion (ROM). The aim of this study was to determine (1) if a spectrum of symptom severity exists during the freezing phase of AC and (2) identify factors associated with patient selection of corticosteroid injection (CSI) for treatment., Methods: Patients presenting within 6 months of symptom onset of AC (freezing phase) were enrolled in this single-site retrospective case control study. Visual analog pain scale (VAS) score, shoulder ROM, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores, and Patient-Reported Outcomes Measurement Information System (PROMIS function and pain) scores were collected. Each patient was offered oral anti-inflammatory medication, physical therapy, and intra-articular CSI. Patients were divided into 2 cohorts: those electing vs. those deferring CSI. Multivariable logistic regression was performed to identify patient or symptom characteristics predictive of electing CSI., Results: A total of 112 patients (mean age = 54.7 ± 8.8 years, female = 76 [67.9%], mean symptom duration = 13.2 ± 7.9 weeks, elected CSI = 74 [66.1%]) were included in our analysis. The overall study population demonstrated a wide spectrum of VAS pain scores (6.0 ± 2.8, range: 0-10) and ROM: forward elevation (99° ± 27°, range: 30°-150°), abduction (82° ± 24°, range: 30°-130°), external rotation (47° ± 13°, range: 0°-90°), internal rotation (38° ± 26°, range: 5°-90°). The CSI group had higher mean VAS pain score (6.6 ± 2.5 vs. 4.9 ± 3.0, P = .005) and greater limitations in ROM for forward elevation (92° ± 27° vs. 113° ± 25°, P = .001) and abduction (77° ± 24° vs. 90° ± 21°, P = .005) compared with the non-CSI cohort. The CSI group demonstrated significantly worse shoulder function based on Constant (P < .05), ASES (P = .001), P-UE (P = .016), P-Intensity (P = .002), and P-Interference (P = .004). Logistic regression demonstrated decreased total shoulder ROM in forward elevation and abduction plane (OR = 0.98, 95% CI = 0.97-0.99, P = .004). Hispanic ethnicity and increased VAS pain score (OR = 1.20, 95% CI = 1.01-1.43, P = .04) were associated with increased likelihood of electing CSI., Conclusion: A spectrum of symptom severity exists during the freezing phase of primary AC, despite similar etiology. AC patients with greater pain severity, and greater limitations in ROM at initial evaluation were associated with patient selection of CSI., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The glenoid labrum acts as a bumper, deepening glenoid concavity and amplifying the concavity-compression mechanism, and serves as the scapular attachment for glenohumeral ligaments. The role of the posterosuperior labrum in anteroinferior glenohumeral stability, and the role of the anterior labrum in posterior stability has been debated. The purpose of this study was to quantify the contribution of anteroinferior and posterosuperior labral tears to loss of glenohumeral stability in multiple directions., Methods: Fourteen fresh-frozen cadaveric shoulders were tested on a custom stability ratio measurement apparatus. The peak force that was required to translate the humeral head in anterior, anteroinferior, posterior, and posteroinferior directions was measured under 5 conditions: intact labrum (n = 14), anteroinferior labral tear (n = 7), posterosuperior labral tear (n = 7), combined labral tear (n = 14), and no labrum (n = 14). The stability ratio was defined as the peak translational force divided by the compressive force. Within force-translation curves, we defined the suction cup effect as the force required to release the negative pressure created by an intact labrum., Results: The suction cup effect was usually present with the intact labrum and always disappeared after removal of the labrum for anterior (100% vs. 0%) and posterior (86% vs. 0%) translations (P < .001). After creation of an anteroinferior labral tear, the stability ratio for posterior direction decreased (P < .001) and the suction cup effect disappeared (P < .001). After creation of a posterosuperior labral tear, stability ratios in the anterior and anteroinferior directions decreased (P ≤ .006) and the suction cup effect disappeared (P ≤ .015). The stability ratio for anterior and anteroinferior testing was more diminished by posterosuperior labral tears than anteroinferior labral tears, and the stability ratio for posterior testing was more diminished by anteroinferior labral tears than posterosuperior labral tears., Conclusion: Anteroinferior labral tears decreased posterior stability and posterosuperior labral tears decreased anterior and anteroinferior stability, largely because of loss of the suction cup effect., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The term shoulder instability refers to a variety of mechanisms and clinical presentations. One of the common pathologies of throwing disorders is internal impingement with anterior instability. Most throwing athletes with symptomatic internal impingement with anterior instability exhibit positive apprehension and relocation test results, whereas those with recurrent anterior shoulder instability display positive apprehension test results. While the glenoid labrum-inferior glenohumeral ligament complex is a significant critical stabilizer for the prevention of anterior shoulder dislocation, the characteristics of the essential lesion in internal impingement with anterior instability have not been determined yet. This study aimed to compare the intra-articular lesion of athletes with internal impingement related to the overhead throwing motion in athletes with a traumatic shoulder dislocation., Methods: Sixty-one athletes (all men; mean age, 25.2 ± 12.6 yr) who underwent an arthroscopic procedure were divided into 2 groups: 25 in the throwing group and 36 in the dislocation group. All shoulders had subtle glenohumeral instability defined by a positive anterior apprehension test and a relocation test. Those with voluntary and multidirectional instability and large glenoid bone loss (more than 25%) were excluded from the current study. All shoulders were evaluated for the following evidence: rotator cuff injury, superior labrum tear anterior and posterior lesions, labral pathologies including Bankart lesions, osteochondral lesions to the humeral head, biceps tendon fraying or rupture, and inferior glenohumeral ligament and middle glenohumeral ligament (MGHL) conditions., Results: Arthroscopic findings of the throwing group showed more supraspinatus injuries (92% and 25%, P < .001), type II superior labrum tear anterior and posterior lesions (60% and 3%, P < .001), posterosuperior labral lesions (92% and 39%, P < .001), and hypoplastic MGHLs (56% and 6%, P < .001) and lesser Bankart lesions (8% and 92%, P < .05) than those of the dislocation group., Conclusions: These results indicate that the characteristic lesions of internal impingement with anterior instability in throwing athletes include partial thickness rotator cuff tears, superior labrum tear anterior and posterior lesions, posterosuperior labral tears, and hypoplastic MGHLs. As expected, the physiopathology of internal impingement with anterior instability in throwing athletes may be related to the dysfunction of the anterosuperior glenohumeral capsular ligament, including the MGHL, rather than the inferior glenohumeral ligament as in traumatic anterior shoulder dislocations. These findings would be useful for defining treatment strategies for internal impingement with anterior instability in overhead throwing athletes., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Osteoarthritis (OA) is a disease of joint degeneration and impaired function. Muscle atrophy, fatty infiltration, and fibrosis are degenerative features of muscle injury and predict poor outcomes in some degenerative and exercise-related injuries. Patients with glenohumeral joint OA usually have rotator cuff muscle degeneration, even though the rotator cuff is intact. However, the mechanism and correlation between OA and degeneration of muscles around joints are still unknown., Methods: Forty-five 12-month-old C57BL/6J mice received a single injection of monoiodoacetic acid into the right glenohumeral joint. The sham group was injected with saline on the same day in the right glenohumeral joint. Three and 6 weeks after the operation, gait analysis was conducted to evaluate the function of the forelimb. Then, the shoulder joint and supraspinatus muscle were collected for histologic staining, reverse transcription quantitative polymerase chain reaction, and biomechanics test. Correlations between fat area fraction in muscle, percentage wet muscle weight change or Osteoarthritis Research Society International score, and gait analysis/muscle mechanics tests were assessed using Pearson's correlation coefficient or Spearman's correlation coefficient., Results: Compared with the sham group, the monoiodoacetic acid group developed significant glenohumeral joint OA and the supraspinatus muscle developed significant fatty infiltration and muscle atrophy. Shoulder function correlated with glenohumeral joint OA/rotator cuff muscle severity, weight loss, and fatty infiltration., Conclusion: In mice, glenohumeral joint OA can lead to rotator cuff degeneration and inferior limb function. The small animal model could be a powerful tool to further study the potential mechanisms between glenohumeral OA and rotator cuff muscle degeneration., (Copyright © 2022. Published by Elsevier Inc.)

Background: Optimal implant placement in reverse total shoulder arthroplasty (rTSA) remains controversial. Specifically, the optimal glenoid inclination is unknown. Therefore, a cadaveric shoulder simulator with 3-dimentional human motion specific to rTSA was used to study joint contact and muscle forces as a function of glenoid component inclination., Methods: Eight human cadaver shoulders were tested before and after rTSA implantation. Scapular plane abduction kinematics from control subjects and those with rTSA drove a cadaveric shoulder simulator with 3-dimentional scapulothoracic and glenohumeral motion. Glenoid inclination varied from -20° to +20°. Outputs included compression, superior-inferior (S/I) shear, and anterior-posterior shear forces from a 6° of freedom load cell in the joint, and deltoid and rotator cuff muscle forces. Data were evaluated with statistical parametric mapping and t-tests., Results: Inferior glenoid inclination (-) reduced S/I shear by up to 125% relative to superior inclination, with similar compression to the neutral condition (0°). Superior inclinations (+) increased the S/I shear force by approximately the same magnitude, yet decreased compression by 25% in the most superior inclination (+20°). There were few differences in deltoid or rotator cuff forces due to inclination. Only the middle deltoid decreased by approximately 7% for the most inferior inclination (-20°). Compared with native shoulders, the neutral (0°) rTSA inclination showed reduced forces of 30%-75% in the anterior deltoid and a trend toward decreased forces in the middle deltoid. Force demands on the rotator cuff varied as a function of elevation, with a trend toward increased forces in rTSA at peak glenohumeral elevation., Conclusions: Inferior inclination reduces superior shear forces, without influencing compression. Superior inclination increased S/I shear, while decreasing compression, which may be a source of component loosening and joint instability after rTSA. Inferior inclination of the rTSA glenoid may reduce the likelihood of glenoid loosening by reducing the magnitude of cyclic shear and compressive loading during arm elevation activities, although this may be altered by specific-subject body habitus and motion. These factors are especially important in revision rTSA or glenoid bone grafting where there is already a 3-fold increase in glenoid baseplate loosening vs. primary rTSA., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Depth sensor-based motion analysis systems are of interest to researchers with low cost, fast analysis capabilities, and portability; thus, their reliability is a matter of interest. Our study examined the agreement and reliability in estimating the basic shoulder movements of Azure Kinect, Microsoft's state-of-the-art depth sensor, and its predecessor, Kinect v2, by comparing them with the gold standard marker-based motion analysis system., Methods: In our study, the shoulder joint ranges of motion of 20 healthy individuals were analyzed during dominant-side flexion, abduction, and rotation movements. The reliability and agreement between methods were evaluated using the intraclass correlation coefficient (ICC) and the Bland-Altman method., Results: Compared to the gold standard method, the old- and new-generation Kinect showed similar performance in terms of reliability in the estimation of flexion (ICC = 0.86 vs. 0.82) and abduction (ICC = 0.78 vs. 0.79) movements, respectively. In contrast, the new-generation sensor showed higher reliability than its predecessor in internal (ICC = 0.49 vs. 0.75) and external rotation (ICC = 0.38 vs. 0.67) movement., Conclusion: Compared to its predecessor, Kinect Azure has higher reliability in analyzing movements in a lower range and variability, thanks to its state-of-the-art hardware. However, the sensor should also be tested on multiaxial movements, such as combing hair, drinking water, and reaching back, which are the tasks that simulate extremity movements in daily life., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Preoperative skin preparations for total shoulder arthroplasty (TSA) are not standardized for Cutibacterium acnes eradication. Topical benzyl peroxide (BPO) and benzyl peroxide with clindamycin (BPO-C) have been shown to reduce the bacterial load of C acnes on the skin. Our aim was to investigate whether preoperative application of these topical antimicrobials reduced superficial colonization and deep tissue inoculation of C acnes in patients undergoing TSA., Methods: In a prospective, single-blinded randomized controlled trial, 101 patients undergoing primary TSA were randomized to receive either topical pHisoHex (hexachlorophene [1% triclosan; sodium benzoate, 5 mg/mL; and benzyl alcohol, 5 mg/mL]) (n = 35), 5% BPO (n = 33), or 5% BPO with 1% clindamycin (n = 33). Skin swabs obtained prior to topical application and after topical application before surgery, as well as 3 intraoperative swabs (dermis after incision, on joint capsule entry, and dermis at wound closure), were cultured. The primary outcome was positive culture findings and successful decolonization., Results: All 3 topical preparations were effective in decreasing the rate of C acnes. The application of pHisoHex reduced skin colonization by 50%, BPO reduced skin colonization by 73.7%, and BPO-C reduced skin colonization by 81.5%. The topical preparation of BPO-C was more effective in decreasing the rate of C acnes at the preoperative and intraoperative swab time points compared with pHisoHex and BPO (P = .003). Failure to eradicate C acnes with topical preparations consistently resulted in deep tissue inoculation. There was an increase in the C acnes contamination rate on the skin during closure (33%) compared with skin cultures taken at surgery commencement (22%)., Conclusion: Topical application of BPO and BPO-C preoperatively is more effective than pHisoHex in reducing colonization and contamination of the surgical field with C acnes in patients undergoing TSA., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.)

Background: The Watson Instability Program (WIP1) is current best evidence for conservative management of atraumatic shoulder instability, but it is unknown if this program can be effectively delivered via tele-consultation. The purpose of this longitudinal pre-post intervention study was to determine the effects of the WIP1 on patient-reported outcome measures, scapular position, shoulder strength, and handstand stability in student circus performers with atraumatic shoulder instability when delivered via tele-consultation., Methods: Student circus performers aged between 15 and 35 years from the National Institute of Circus Arts were recruited. A 12-week shoulder exercise program was delivered via tele-consultation during the Melbourne, Australia COVID-19 (coronavirus disease 2019) lockdown. The primary outcome measures were the Western Ontario Shoulder Instability Index score and the Melbourne Instability Shoulder Scale score. Secondary outcomes measures included the Orebro Musculoskeletal Pain Questionnaire, the Tampa Scale for Kinesiophobia, and physical assessment measures including strength via handheld dynamometry, scapular position using an inclinometer, and handstand stability via center-of-pressure fluctuation. Patient-reported outcomes were collected at baseline and 6-week, 12-week, 6-month, and 9-month time points, and physical outcomes were measured at baseline and 9-month time points. A repeated-measures mixed model (with effect sizes [ESs] and 95% confidence intervals [CIs]) was used to analyze patient-reported outcomes, handstand data, strength, and scapular measures. Significance was set at P < .05., Results: Twenty-three student circus arts performers completed the study. Significant improvements were found in both Western Ontario Shoulder Instability Index scores (effect size [ES], 0.79 [95% CI, 0.31-1.33] at 6 weeks; ES, 1.08 [95% CI, 0.55-1.6] at 12 weeks; ES, 1.17 [95% CI, 0.62-1.78] at 6 months; and ES, 1.31 [95% CI, 0.74-1.95] at 9 months; P < .001) and Melbourne Instability Shoulder Scale scores (ES, 0.70 [95% CI, 0.22-1.22] at 6 weeks; ES, 0.83 [95% CI, 0.34-1.37] at 3 months; ES, 0.98 [95% CI, 0.46-1.54] at 6 months; and ES, 0.98 [95% CI, 0.43-1.50] at 9 months; P < .001), as well as Orebro Musculoskeletal Pain Questionnaire scores at all follow-up time points. The Tampa Scale for Kinesiophobia scores reached significance at 6 weeks and 12 weeks. Following rehabilitation, we found statistically significant increases in shoulder strength in all positions tested and increased scapular upward rotation measured at end-of-range abduction, as well as during loaded external rotation. The affected arm showed greater instability than the unaffected arm with a significant intervention effect on the affected arm showing a greater consistent anterior-posterior movement pattern., Conclusion: In a group of circus performers with atraumatic shoulder instability, treatment with the WIP1 via telehealth resulted in clinically and statistically significant improvements in shoulder symptoms and function., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

This review sets forth an approach to performing and interpreting shoulder ultrasound in patients with prior rotator cuff repair and presents a comprehensive review of normal expected findings, postsurgical complications and common artifacts encountered in clinical practice., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Despite the fact that primary adhesive capsulitis of the glenohumeral joint is often considered a self-limiting condition, not all patients make a full recovery. Manipulation under anesthesia (MUA) is performed to forcibly rupture the contracted capsule in a controlled manner. However, the technique, timing, and use of additional injections are often debated. In this study, we report the outcomes following the addition of capsular distension and countertraction to MUA as a treatment for adhesive capsulitis., Methods: We performed a retrospective case-cohort study comparing 3 groups: Group 1 underwent MUA alone (n = 54); group 2, MUA with capsular distension (n = 114); and group 3, MUA with capsular distension and countertraction (n = 167). The re-MUA rate, Constant-Murley shoulder (CMS) score, and visual analog scale (VAS) score (for pain) were measured after 6 weeks and 6 months., Results: The re-MUA rate fell with the addition of both capsular distension and countertraction: 63% in group 1, 39% in group 2, and 18% in group 3. Patients in group 3 recorded the greatest improvement in the CMS score after 6 weeks (+90% vs. +68% in group 2 and +58% in group 1), with all groups showing improvements compared with before treatment. The only independent risk factor identified for re-MUA was smoking. If a second MUA was performed, the CMS (+67%) and VAS (+61%) scores improved, but at 6 months, the CMS score (74.57 ± 7.6 vs. 83.30 ± 5.5) and VAS score (10.57 ± 1.8 vs. 12.96 ± 1.5) remained inferior to those of patients who only needed a single MUA., Discussion and Conclusion: MUA combined with capsular distension and countertraction reduces the need for a second MUA and results in a faster improvement in functional outcome (CMS score) and reduction of pain (VAS score) compared with MUA alone or MUA with capsular distension. The results of this case-cohort study are of clinical relevance because they show that the efficacy of an MUA can be improved through relatively simple adaptations of the treatment protocol., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The scapular structures that have not yet been assigned anatomic terms generate a challenge in clinical diagnostics and surgical application, as well as in scientific observation. The aim of this study was to solve the lack in terminology concerning the scapula and the scapular region., Methods: Observation and description of 29 structures were carried out on both dry scapulae and radiographs of the shoulder joint. In addition, several terms commonly encountered throughout the literature concerning the scapula were revised. A degree of consensus was reached by using the Delphi method surveying the opinions of 21 invited experts in the field. Taxonomy panels and etymology of anatomic terminology were considered in the generation of the proposed terms., Results: The scapula was redefined as a lamina with projecting processes, and several landmarks demarcating certain newly defined topographic spaces were highlighted via 2 rounds of Delphi systematic voting and discussion. The overall level of the peer nominees' consensus was high. Few terms received a neutral opinion., Conclusions: This study communicates a proposal of 16 new terms defining grossly visible structures on the scapula that have not yet been described by officially recognized terms, including a call to unify 13 previously contributed terms that have not been codified and are often used interchangeably within different surgical and scientific fields. Incorporating these terms into the anatomic nomenclature would facilitate communication accuracy and eliminate ambiguity among clinicians, surgeons, and anatomists., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Diabetic patients have a greater incidence of adhesive capsulitis (AC) and a more protracted disease course than patients with idiopathic AC. The purpose of this study was to compare gene expression differences between AC with diabetes mellitus and AC without diabetes mellitus., Methods: Shoulder capsule samples were prospectively obtained from diabetic or nondiabetic patients who presented with shoulder dysfunction and underwent arthroscopy (N = 16). Shoulder samples of AC with and without diabetes (n = 8) were compared with normal shoulder samples with and without diabetes as the control group (n = 8). Shoulder capsule samples were subjected to whole-transcriptome RNA sequencing, and differential expression was analyzed with EdgeR. Only genes with a false discovery rate < 5% were included for further functional enrichment analysis., Results: The sample population had a mean age of 47 years (range, 24-62 years), and the mean hemoglobin A 1c level for nondiabetic and diabetic patients was 5.18% and 8.71%, respectively. RNA-sequencing analysis revealed that 66 genes were differentially expressed between diabetic patients and nondiabetic patients with AC whereas only 3 genes were differentially expressed when control patients with and without diabetes were compared. Furthermore, 286 genes were differentially expressed in idiopathic AC patients, and 61 genes were differentially expressed in diabetic AC patients. On gene clustering analysis, idiopathic AC was enriched with multiple structural and muscle-related pathways, such as muscle filament sliding, whereas diabetic AC included a greater number of hormonal and inflammatory signaling pathways, such as cellular response to corticotropin-releasing factor., Conclusions: Whole-transcriptome expression profiles demonstrate a fundamentally different underlying pathophysiology when comparing diabetic AC with idiopathic AC, suggesting that these conditions are distinct clinical entities. The new genes expressed explain the differences in the disease course and suggest new therapeutic targets that may lead to different treatment paradigms in these 2 subsets., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Rotator cuff fatty infiltration (FI) is one of the most important parameters to predict the outcome of certain shoulder conditions. The primary objective of this study was to define a new computed tomography (CT)-based quantitative 3-dimensional (3D) measure of muscle loss (3DML) based on the rationale of the 2-dimensional (2D) qualitative Goutallier score. The secondary objective of this study was to compare this new measurement method to traditional 2D qualitative assessment of FI according to Goutallier et al and to a 3D quantitative measurement of fatty infiltration (3DFI)., Materials and Methods: 102 CT scans from healthy shoulders (46) and shoulders with cuff tear arthropathy (21), irreparable rotator cuff tears (18), and primary osteoarthritis (17) were analyzed by 3 experienced shoulder surgeons for subjective grading of fatty infiltration according to Goutallier, and their rotator cuff muscles were manually segmented. Quantitative 3D measurements of fatty infiltration (3DFI) were completed. The volume of muscle fibers without intramuscular fat was then calculated for each rotator cuff muscle and normalized to the patient's scapular volume to account for the effect of body size (NV fibers ). 3D muscle mass (3DMM) was calculated by dividing the NV fibers value of a given muscle by the mean expected volume in healthy shoulders. 3D muscle loss (3DML) was defined as 1 - (3DMM). The correlation between Goutallier grading, 3DFI, and 3DML was compared using a Spearman rank correlation., Results: Interobserver reliability for the traditional 2D Goutallier grading was moderate for the infraspinatus (ISP, 0.42) and fair for the supraspinatus (SSP, 0.38), subscapularis (SSC, 0.27) and teres minor (TM, 0.27). 2D Goutallier grading was found to be significantly and highly correlated with 3DFI (SSP, 0.79; ISP, 0.83; SSC, 0.69; TM, 0.45) and 3DML (SSP, 0.87; ISP, 0.85; SSC, 0.69; TM, 0.46) for all 4 rotator cuff muscles (P < .0001). This correlation was significantly higher for 3DML than for the 3DFI for SSP only (P = .01). The mean values of 3DFI and 3DML were 0.9% and 5.3% for Goutallier 0, 2.9% and 25.6% for Goutallier 1, 11.4% and 49.5% for Goutallier 2, 20.7% and 59.7% for Goutallier 3, and 29.3% and 70.2% for Goutallier 4, respectively., Conclusion: The Goutallier score has been helping surgeons by using 2D CT scan slices. However, this grading is associated with suboptimal interobserver agreement. The new measures we propose provide a more consistent assessment that correlates well with Goutallier's principles. As 3DML measurements incorporate atrophy and fatty infiltration, they could become a very reliable index for assessing shoulder muscle function. Future algorithms capable of automatically calculating the 3DML of the cuff could help in the decision process for cuff repair and the choice of anatomic or reverse shoulder arthroplasty., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Decreases in bone density of the scapula due to age and disease can make orthopedic procedures such as arthroplasty and fracture fixation challenging. There is limited information in the literature regarding the effect of age and sex on the patterns of these density changes across the bone. Characterizing these changes could assist the surgeon in planning optimal instrumentation placement., Methods: Ninety-seven 3-dimensional models of the scapula were segmented from routine clinical computed tomography scans, and an opportunistic quantitative computed tomography approach was used to obtain detailed calibrated bone density measurements for each bone model. The effects of age and sex on cortical and trabecular bone density were assessed for the entire scapula. Specific regions (eg, scapular spine) where these factors had a significant effect were identified. Three-dimensional models were generated to allow clear visualization of the changes in density patterns., Results: Cortical bone loss averaged 1.0 mg/cm 3 and 0.3 mg/cm 3 per year for female and male subjects, respectively, and trabecular bone loss averaged 1.6 mg/cm 3 and 1.2 mg/cm 3 , respectively. However, several regions had loss rates several times greater. Areas that were significantly affected by age included the acromion, scapular spine, base of the coracoid, inferior glenoid neck, and glenoid vault. Areas that were significantly affected by sex were the scapular spine and body., Conclusions: These findings provide evidence that the bone density distribution across the scapula changes non-uniformly because of factors including sex and age. Despite overall trends of bone loss, there remains significant variability between individuals, and subject-specific tools for planning surgical procedures in which scapular fixation is required may be beneficial., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Humeral torsion (HT) has been linked to pitching arm injury risk after controlling for shoulder range of motion. Currently measuring HT uses expensive equipment, which inhibits clinical assessment. Developing an HT predictive model can aid clinical baseball arm injury risk examination. Therefore, the purpose of this study was to develop and internally validate an HT prediction model using standard clinical tests and measures in professional baseball pitchers., Methods: An 11-year (2009-2019) prospective professional baseball cohort was used for this study. Participants were included if they were able to participate in all practices and competitions and were under a Minor League Baseball contract. Preseason shoulder range of motion (external rotation [ER], internal rotation [IR], horizontal adduction [HA]) and HT were collected each season. Player age, arm dominance, arm injury history, and continent of origin were also collected. Examiners were blinded to arm dominance. An a priori power analysis determined that 244 players were needed for accurate prediction models. Missing data was low (<3%); thus, a complete case analysis was performed. Model development followed the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD) recommendations. Regression models with restricted cubic splines were performed. Following primary model development, bootstrapping with 2000 iterations were performed to reduce overfitting and assess optimism shrinkage. Prediction model performance was assessed through root mean square error (RMSE), R 2 , and calibration slope with 95% confidence intervals (CIs). Sensitivity analyses included dominant and nondominant HT., Results: A total of 407 professional pitchers (age: 23.2 [standard deviation 2.4] years, left-handed: 17%; arm history prevalence: 21%) participated. Predictors with the highest influence within the model include IR (0.4, 95% CI 0.3, 0.5; P < .001), ER (-0.3, 95% CI -0.4, -0.2; P < .001), HA (0.3, 95% CI 0.2, 0.4; P < .001), and arm dominance (right-handed: -1.9, 95% CI -3.6, -0.1; P = .034). Final model RMSE was 12, R 2 was 0.41, and calibration was 1.00 (95% CI 0.94, 1.06). Sensitivity analyses demonstrated similar model performance., Conclusions: Every 3° of IR explained 1° of HT. Every 3° of ER explained 1° less of HT, and every 7° of HA explained 1° of HT. Right-handers had 2° less HT. Models demonstrated good predictive performance. This predictive model can be used by clinicians to infer HT using standard clinical test and measures. These data can be used to enhance professional baseball arm injury examination., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The purpose of this study was to compare the efficacy of blue light therapy (BLT) and 5% topical benzoyl peroxide (BPO) gel in combination with standard chlorhexidine (CHX) preparation in eradicating Cutibacterium acnes at the deltopectoral interval measured by positive, quantitative culture findings., Methods: Adult male volunteers were randomized to 1 of 3 treatment groups: BPO, BLT, and BPO followed by BLT. Contralateral shoulders served as matched controls. Volunteers randomized to BPO applied the gel for a total of 5 treatments. In the BLT group, a single 23-minute treatment was administered at an estimated irradiance of 40 mW/cm 2 (radiant exposure, 55.2 J/cm 2 ). In the BPO-BLT group, volunteers received both treatments as described earlier. After treatment with either BPO, BLT, or both, a single swab culture was taken from the treatment shoulder. Next, control and treatment shoulders were prepared with CHX, and cultures were taken from each shoulder. Cultures were sent for anaerobic quantitative growth analysis with both polymerase chain reaction and Sanger sequencing confirmation of presumptive C acnes colonies., Results: This study enrolled 60 male volunteers, 20 per group, with no loss to follow-up. After treatment but prior to CHX administration, all culture samples in the BPO group and BLT group grew C acnes. Prior to CHX, 16 samples (80%) in the BPO-BLT group grew C acnes. On quantitative analysis, the BPO group and BPO-BLT group had significantly less growth of C acnes compared with the BLT group after treatment but prior to CHX (P < .05 for each). Following CHX administration, the BPO and BPO-BLT groups had significantly fewer positive culture findings (odds ratios of 0.03 and 0.29, respectively) and less quantity of growth compared with their control arms (P < .05). This was not seen in the BLT group. For quantitative between-group analysis, no significant synergistic effects were seen with BPO-BLT compared with BPO alone (P = .688). There was no difference in side effects between groups., Conclusion: The combination of topical BPO and CHX was effective at eliminating C acnes in most cases. BLT alone did not demonstrate effective antimicrobial properties against C acnes at the radiant exposure administered in this study. Combining BPO and BLT did not lead to significant synergistic antimicrobial effects. Both BPO and BLT are safe with few, transient side effects reported. More work is needed to determine whether BLT at higher radiant exposures or serial treatment results in bactericidal effects against C acnes in vivo., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the effects of diabetes and corticosteroid injected in the joints on the shoulder motion, gait, and joint capsular properties in a rat stiffness model., Methods: A total of 27 rats were randomly distributed into 3 groups-nondiabetes group (group A), diabetes group (group B), and diabetes plus steroid injection group (group C). The diabetes model was developed by inducing hyperglycemia with a submaximal dose of streptozotocin and the stiffness model by completely immobilizing the right shoulder of each animal in all groups with sutures passed between the scapula and humeral shaft. The left shoulder was used as an untreated control in all groups. Three weeks after immobilization, the sutures were removed in all groups, and a single dose of triamcinolone acetonide (0.5 mg/kg) was injected into the glenohumeral joint in group C. After 3 weeks of free activity, range of motion (ROM) evaluation, gait analysis by stride length, and capsular area measurement were performed in all rats., Results: Hyperglycemia was successfully induced with a mean blood glucose level of 448.9±55.9 mg/dL in group B and 431.6±17.8 mg/dL in group C, which were significantly higher than 136.5±13.4 mg/dL in group A (P < .001). A significantly smaller ROM and stride length were found in the right (stiffness-induced) shoulder than that in the left (control) shoulder only in group B, and significantly larger capsular area in the right shoulder than that in the left shoulder in groups A and B (all P < .05). However, in group C, there were no differences between the right and left shoulders in all measurements (all P > .05). In case of the right shoulders in each group, group C showed significantly larger ROM (68° ± 11° vs. 42° ± 7°) and smaller capsular area (3934.4 ± 537.1 pixels vs. 7402.3 ± 1840.3 pixels) than group B (all P < .0167)., Conclusions: The diabetic model had a detrimental effect on the development of stiffness by thickening the joint capsule, and an intra-articular steroid injection resolved the thickened joint capsule and restored shoulder motion., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The biomechanical relationship between irreparable rotator cuff tear size and glenohumeral joint stability in the setting of superiorly directed forces has not been characterized. The purpose of this study was to quantify kinematic alterations of the glenohumeral joint in response to superiorly directed forces in a progressive posterosuperior rotator cuff tear model., Methods: Nine fresh-frozen cadaveric shoulders (mean age; 58 years) were tested with a custom shoulder testing system. Three conditions were tested: intact, stage II (supraspinatus) tear, stage III (supraspinatus + anterior half of infraspinatus) tear. At each condition, range of motion and humeral head positions were measured with a "balanced" loading condition, and with a superiorly directed force ("unbalanced loading condition"). At each of the 0°, 20°, and 40° of glenohumeral abduction positions, all measurements were made at 0°, 30°, 60°, and 90° of external rotation (ER). Two-way repeated measures analysis of variance with Tukey post hoc tests were performed for statistical analyses., Results: With the balanced load, no significant change in superior humeral head position was observed in stage II tears. Stage III tears significantly changed the humeral head position superiorly at 30° and 60° ER at each abduction angle compared with the intact condition (P ≤ .028). With superiorly directed load, stage II and stage III tears both showed statistically significant increases in superior translation at all degrees of ER for all degrees of abduction (P ≤ .035), except stage II tears at 0° ER and 40° abduction (P = .185) compared with the intact condition. Stage II tears showed posterior translations with 30° and 60° ER, both at 20° and 40° of abduction. Stage III tears also showed posterior translations with 90° ER for all abduction angles (P ≤ .039)., Conclusion: With superiorly directed loads, complete supraspinatus tendon tears created superior translations at all abduction angles, and posterior instability in the middle ranges of rotation for 20° and 40° of abduction. Larger tears involving the anterior half of the infraspinatus tendon caused significant superior and posterior translations within the middle ranges of ER for all abduction angles. In addition to superior instability, posterior translation should be considered when selecting or developing surgical techniques for large posterosuperior rotator cuff tears., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The impact of surgical timing on outcomes involving traumatic rotator cuff tears (RCTs) remains uncertain. The purpose of this study was to determine how functional outcomes are affected by surgical timing in traumatic RCTs., Methods: We performed a retrospective review of patients with repair of traumatic full-thickness RCTs. Preoperative magnetic resonance imaging scans were evaluated by 2 blinded reviewers to measure RCT area and muscular atrophy. Functional outcomes were assessed via the American Shoulder and Elbow Surgeons (ASES) score, Single Assessment Numeric Evaluation (SANE) score, Simple Shoulder Test score, and visual analog scale (VAS) pain score. Patients were divided into 4 groups based on the time from injury to surgery: 0-2 months (group 1), 2-4 months (group 2), 4-6 months (group 3), and 6-12 months (group 4). Multivariate analysis was performed to assess the impact of surgical timing on functional outcomes. A subanalysis was performed to assess outcomes in patients who underwent surgery within 3 weeks of injury., Results: The study included 206 patients (150 men and 56 women) with a mean age of 60.0 ± 9.7 years and a minimum of 24 months' clinical follow-up (mean, 35.5 months; range, 24-54.4 months). The average tear area was 8.4 ± 6.3 cm 2 in group 1 (66 patients), 5.8 ± 5.1 cm 2 in group 2 (76 patients), 5.1 ± 4.6 cm 2 in group 3 (29 patients), and 3.7 ± 3.1 cm 2 in group 4 (35 patients) (P < .001). There were significant differences between the 4 cohorts in the final postoperative ASES score (P = .030) and VAS pain score (P = .032). The multivariate regression demonstrated that patients who underwent surgery within 4 months of injury had estimated improvements of 10.3 points in the ASES score (P = .008), 1.8 points in the Simple Shoulder Test score (P = .001), 8.6 points in the SANE score (P = .033), and 0.93 points in the VAS pain score (P = .028) compared with patients who underwent surgery later. The subanalysis demonstrated that patients who underwent surgery within 3 weeks of injury (n = 13) had significantly better VAS (P = .003), ASES (P = .008), and SANE (P = .019) scores than patients who underwent surgery at between 3 weeks and 4 months after injury (n = 129)., Conclusions: This study demonstrates that surgical repair of traumatic RCTs results in significant improvements in functional outcomes for all patients; however, patients who undergo surgery within 3 weeks can expect the best functional outcomes, with a drop in function in patients who undergo surgery >4 months after injury., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Rotator cuff (RC) tears have been widely studied as many treatment strategies have been recommended. However, optimal management for patients with RC tears is still unclear., Purpose: The main aim of this systematic review was to analyze randomized controlled trials using meta-analysis to compare repair to conservative treatments for patients with any type of RC tear., Methods: MEDLINE, Cochrane Library (CENTRAL database), PEDro, and Scopus databases were used. Two independent reviewers selected randomized controlled trials that compared surgical to conservative treatments for RC tear patients. The studies included were assessed using Cochrane Risk of Bias 2 tools, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was used to evaluate the certainty of evidence and to summarize the study conclusions., Results: Six trials were included. Pooled results showed improvement in function and pain perception in favor of the repair group at 6 months (mean difference 1.26, 95% CI -2.34, 4.85, P = .49; and -0.59, 95% CI -0.84, -0.33, P < .001, respectively), at 12 months (mean difference 5.25, 95% CI 1.55, 8.95, P = .005, for function; and -0.41, 95% CI -0.70, -0.12, P = .006, for pain) and at 24 months (mean difference 5.57, 95% CI 1.86, 9.29, P = .003, for function; and -0.92, 95% CI -1.31, -0.52, P < .001, for pain) in RC tear patients. However, these differences did not reach the minimum clinically important difference. The certainty of evidence ranged from low to moderate because of imprecision in the studies included., Conclusions: Overall analysis showed that in patients with RC tear, repair compared with conservative treatment could result in increased pain reduction and functional improvement at 6, 12, and 24 months. Even if these effects were often statistically significant, their clinical relevance was limited. Moreover, the certainty of body of evidence ranged from low to moderate., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Follow-up magnetic resonance imaging (MRI) after rotator cuff repair can sometimes demonstrate healing with nontendinous tissue that extends from the footprint to the retracted tendon end, which is inferred as fibrous tissue formation. The aim was to investigate this particular finding and its significance., Methods: There were 494 eligible cases of healed supero-posterior medium-sized to massive rotator cuff repairs, after the exclusion of retears. A retrospective review was performed for the 3 groups that were divided according to their MRI appearances of healing: type I described the direct healing of the tendon to the footprint, whereas type II demonstrated the distinctive continuity of nontendinous tissue from the footprint to the retracted tendinous portion, and type III also showed a similar appearance but with obvious thinning of the tissue, without any evidence of defect confirmed on the routine outpatient ultrasonograph., Results: Only 108 of 494 patients (21.9%) demonstrated type I healing, whereas the signs of nontendinous healing were evident for the rest, with the 116 patients (23.5%) being classified as type III with attenuation. Comparing the preoperative tendon retraction, 34.8% and 37.2% of the Patte stages 2 and 3, respectively, resulted in type III healing, which were significantly higher compared with that of stage 1 (15.3%, P < .001). Type III healing had the highest average preoperative Goutallier grades. The average postoperative visual analog scale and the American Shoulder and Elbow Surgeons (ASES) scores have improved significantly for all 3 groups (P < .05), with the ASES score being 86.1±15.9 for type I, 93.7±36.1 for type II, and 87.8±15.1 for type III without significant differences between the groups (P = .3)., Conclusions: Only a fifth of the rotator cuff repairs led to a direct healing to the footprint, and the rest healed with MRI appearance of nontendinous tissue formation bridging the retracted tendinous portion and the footprint. These MRI appearances did not represent the true tendinous tissue formation between the torn end of the tendon and the bone after healing. Such appearances did not seem to affect the clinical outcomes., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Acellular dermal matrix (ADM) allografts are commonly used in the surgical treatment of complex and irreparable rotator cuff tears. Multiple studies report that superior capsule reconstruction (SCR) using ADM has resulted in short-term clinical success as assessed via radiographic and patient-reported outcomes. However, limited information is available regarding the biologic fate of these grafts in human subjects. This case series describes histologic results from 8 patients who had reoperations, during which the previously implanted ADMs were removed. These explanted ADMs were subjected to histologic analysis with the hypothesis that they would have evidence of recellularization, revascularization, and active remodeling., Methods: Eight patients, 38-82 years old, underwent reoperation 6-38 months after undergoing SCR. ADM explants were voluntarily shipped to the manufacturer for histologic analysis. Each graft's structure and composition were qualitatively evaluated by 1 or more of the following histologic stains: hematoxylin and eosin, safranin O, and Russell-Movat pentachrome. Pan-muscle actin staining also assessed the level of neovascularization, potential myoblast or myocyte infiltration, and muscle tissue development in the graft, and was analyzed to determine the proportion of graft that had been recellularized in situ., Results: Grafts showed varying levels of gross and microscopic incorporation with the host. An uneven, but high, overall degree of recellularization, revascularization, and active remodeling was observed. The degree of remodeling correlated with implant duration. These results are consistent with successful biologic reconstruction of the superior shoulder capsule., Conclusions: The present histologic analysis suggests that ADMs used in SCR undergo active recellularization, revascularization, and remodeling as early as 6 months after implantation, and that graft recellularization positively correlates with duration of implantation. These results represent a significant advancement in our knowledge regarding biologic incorporation of ADMs used in SCR., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Because nerve injury of muscles around the shoulder can be easily disguised by "trick movements" of the trunk, shoulder dysfunction following brachial plexus injury is difficult to quantify with conventional clinical tools. Thus, to evaluate brachial plexus injury and quantify its biomechanical consequences, we used inertial measurement units, which offer the sensitivity required to measure the trunk's subtle movements., Methods: We calculated 6 kinematic scores using inertial measurement units placed on the upper arms and the trunk during 9 functional tasks. We used both statistical and machine learning techniques to compare the bilateral asymmetry of the kinematic scores of 15 affected and 15 able-bodied individuals (controls)., Results: Asymmetry indexes from several kinematic scores of the upper arm and trunk showed a significant difference (P < .05) between the affected and control groups. A bagged ensemble of decision trees trained with trunk and upper arm kinematic scores correctly classified all controls. All but 2 patients were also correctly classified. Upper arm scores showed correlation coefficients ranging from 0.55-0.76 with conventional clinical scores., Conclusions: The proposed wearable technology is a sensitive and reliable tool for objective outcome evaluation of brachial plexus injury and its biomechanical consequences. It may be useful in clinical research and practice, especially in large cohorts with multiple follow-ups., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Studies on the effects of manipulation under anesthesia (MUA) for primary stiff shoulder when different comorbidities are present are lacking. Our aim was to assess how comorbidities influence the recovery speed and clinical outcomes after MUA., Methods: Between April 2013 and September 2018, 281 consecutive primary stiff shoulders in the frozen phase treated with MUA were included in this study. We investigated the comorbidities of patients and divided them into the control (n = 203), diabetes mellitus (DM) (n = 32), hyperlipidemia (n = 26), and thyroid disorder (n = 20) groups. The range of motion (ROM) and clinical scores for each group before MUA and 1 week, 6 weeks, and 3 months after MUA were comparatively analyzed. We identified the ROM recovery time after MUA and the responsiveness to MUA. Then, subjects were subdivided into early and late recovery groups based on their recovery time and into successful and nonsuccessful MUA groups based on their responsiveness to MUA., Results: Significant improvements in ROM and clinical scores at 3 months after MUA were observed in all groups. Significant differences in ROM among the 4 groups were also observed during follow-up (P < .05). The DM group had significantly lower ROM values, even at 3 months after MUA, compared with the control group. The ROM recovery speed after MUA was slowest in the DM group, followed by the thyroid disorder, hyperlipidemia, and control groups. Most (90.6%) of the DM group experienced late recovery. The proportion of nonsuccessful MUA was higher in the DM and thyroid disorder groups than that in the control and hyperlipidemia groups (P = .004). During follow-up, there were no differences among groups regarding the visual analog scale, University of California at Los Angeles shoulder, and Constant scores., Conclusion: The ROM recovery speed and responsiveness to MUA for primary stiff shoulder were poorer for the DM and thyroid disorder groups than for the control group. In particular, compared with any other disease, outcomes were poorer when the comorbidity was DM. If patients have comorbidities, then they should be informed before MUA that the comorbidity could affect the outcomes of treatment., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study is to evaluate the short-term complication rate following the open and arthroscopic Latarjet procedures and to meta-analyze the studies comparing the 2 approaches., Methods: PubMed was searched according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines to find clinical and biomechanical studies comparing complication rates in open and arthroscopic Latarjet procedures. A literature search of MEDLINE, Embase, and the Cochrane Library was performed based on the PRISMA guidelines. Clinical studies reporting on the complications following the open or arthroscopic Latarjet were included. Meta-analysis was performed for comparative studies using Review Manager, version 5.3. A P value of <.05 was considered statistically significant., Results: Overall, 89 studies (Level of Evidence [LOE] I: 2, LOE II: 2, LOE III: 24, LOE IV: 61) met inclusion criteria, with 7175 shoulders. Following the open Latarjet procedure, the overall complication rate was 6.1%, with a 1.9% occurrence of graft-related complications, 1.1% hardware, 1.1% wound, 0.9% nerve, and 1.2% other complications. Following the arthroscopic Latarjet procedure, the overall complication rate was 6.8%, with a 3.2% occurrence of graft-related complications, 1.9% hardware, 0.5% wound, 0.7% nerve, and 0.5% other complications. Complications were reported in 7 studies comparing 379 patients treated with the open Latarjet and 531 treated with the arthroscopic Latarjet, with no statistically significant difference between the two (P = .81)., Conclusion: Our study established that the overall complication rate following the Latarjet procedure was 6%-7%, with the most common complication being graft-related. Furthermore, based on the current evidence, there is no significant difference in the complication rate between the open and arthroscopic Latarjet procedures., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Superior capsular reconstruction (SCR) treatment of massive, symptomatic, irreparable rotator cuff tears (RCTs) has become a more recently used procedure. However, there is a lack of consensus surrounding optimal graft choice for the SCR technique, and current dermal grafts have increased cost and are technically challenging because of a need for multiple implants. The purpose of this study was to biomechanically investigate a biological lower-cost alternative as a support for the superior capsule reconstruction concept: an isolated semitendinosus tendon (STT) allograft and a combination graft with the long head of the biceps tendon (LHBT) in an established massive posterosuperior RCT cadaver model., Methods: Ten fresh-frozen cadaveric shoulders (53.3 ± 12.4 years: range: 26-65) were tested on an established dynamic shoulder simulator using dynamic muscle loading. Cumulative deltoid forces, maximum abduction angle, and superior humeral head translation were compared across 4 testing conditions: (1) intact state, (2) massively retracted (Patte III), irreparable posterosuperior RCT, (3) SCR repair using an STT allograft, and (4) SCR repair using a combined STT-LHBT repair., Results: Intact shoulders required a mean deltoid force of 154.2 ± 20.41 N to achieve maximum glenohumeral abduction (55.3° ± 2.3°). Compared with native shoulders, the maximum abduction angle decreased following a massively retracted posterosuperior RCT by 52% (28.3° ± 8.4°; P < .001), whereas the cumulative deltoid forces increased by 48% (205.3 ± 40.9 N; P = .001). The STT repair and the STT-LHBT repair improved shoulder function compared with the tear state, with a mean maximum abduction angle of 30.6° ± 9.0° and 31.8° ± 7.7° and a mean deltoid force of 205.3 ± 40.9 N and 201.0 ± 34.0 N, respectively, but this was not statistically significant (P > .05). The STT-LHBT repair significantly improved the range of motion with respect to the tear state (P = .04)., Conclusions: In a dynamic shoulder simulator model, both the STT and the STT-LHBT repair techniques improved glenohumeral joint kinematics in an amount similar to previously reported "traditional" SCR techniques for treatment of an irreparable posterosuperior RCT., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Rotator cuff tears (RCTs) remain a significant source of pain and disability in the shoulder. Although much work has been done in the study of the effects of rotator cuff tears on glenohumeral joint motion, much less has been done in understanding the effect of rotator cuff tearing on scapular motion or activation. It remains unknown whether scapular dyskinesis is causative or adaptive. The purpose of this study was to systematically review the literature to determine the relationship between rotator cuff tear presence and size on scapular motion, and if rotator cuff repair restored normal motion., Methods: A systematic review using PRISMA guidelines was accomplished to include all studies with biomechanical or clinical outcomes of scapular motion in the presence of RCTs. Studies were excluded if they involved shoulder arthroplasty, rotator cuff tendinopathy, or shoulder impingement without an RCT. From 530 initial references, 42 manuscripts were selected for full review and cross referenced. All studies were evaluated for inclusion and exclusion criteria., Results: Sixteen studies including 335 rotator cuff tears were included in the final review. There were several findings of interest in the literature. First, although all studies demonstrated scapular dyskinesis, they did not report a consistent pattern of motion in the presence of an RCT. In general, scapular posterior tilt was decreased, and scapular upward rotation was increased, especially in large tears, but the literature was unclear as to whether this was a result of the RCT or an adaptive attempt to maintain elevation. Larger RCTs resulted in more pronounced scapular dysfunction, but there was significant variability within studies. Further, dyskinesis was confounded by pain with more abnormal movement in symptomatic vs. asymptomatic RCTs, the latter of which were not different from normal healthy controls. Four studies addressed the effect of RCT on scapular mechanics and found that repair consistently improved it compared to the normal side, but the time to normalization varied between 5 months and 2 years., Conclusion: Scapular motion is abnormal in the presence of an RCT, but the literature is inconsistent regarding a universally affected variable or consistent degree of scapular dysfunction in this setting. Furthermore, it remains unknown which changes are adaptive vs. pathologic. Understanding the relationship between rotator cuff tearing and scapular dyskinesis will require better biomechanical models that consider scapular dyskinesis in their design., (Copyright © 2021. Published by Elsevier Inc.)

Background: Anterior shoulder instability is a common complaint of young athletes. Posterior instability in this population is less well understood, and the standard of care has not been defined. The purpose of the study is to compare index frequency, treatment choice, and athlete disability following an incident of anterior or posterior shoulder instability in high school and collegiate athletes., Methods: A total of 58 high school and collegiate athletes (n=30 athletes with anterior instability; n=28 athletes with posterior instability) were included. Athletes suffering from a traumatic sport-related shoulder instability episode during a team-sponsored practice or game were identified by their school athletic trainer. Athletes were referred to the sports medicine physician or orthopedic surgeon for diagnosis and initial treatment choice (operative vs. nonoperative). Athletes diagnosed with traumatic anterior or posterior instability who completed the full course of treatment and provided pre- and post-treatment patient-reported outcome measures were included in the study. The frequency of shoulder instability was compared by direction, mechanism of injury (MOI), and treatment choice through χ 2 analyses. A repeated measures analysis of variance was used to compare the functional outcomes by treatment type and direction of instability (α = 0.05)., Results: Athletes diagnosed with anterior instability were more likely to report a chief complaint of instability (70%), whereas those diagnosed with posterior instability reported a primary complaint of pain interfering with function (96%) (P = .001). The primary MOI classified as a contact event was similar between anterior and posterior instability groups (77% vs. 54%, P = .06) as well as the decision to proceed with surgery (60% vs. 72%, P = .31). In patients with nonoperative care, athletes with anterior instability had significantly more initial disability than those with posterior instability (32±6.1 vs. 58±8.1, P = .001). Pre- and post-treatment Penn Shoulder Scores for athletes treated with early surgery were similar (P > .05). There were no differences in functional outcomes at discharge in those treated nonoperatively regardless of direction of instability (P = .24); however, change in Penn score was significantly greater in those with anterior (61±18.7) than those with posterior (27 ± 25.2) instability (P = .002)., Conclusion: Athletes with anterior instability appear to have different mechanisms and complaints than those with posterior instability. Among those that receive nonoperative treatment, athletes with anterior instability have significantly greater initial disability and change in disability than those with posterior disability during course of care., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The infraspinatus muscle has a crucial role in shoulder stability. Although axial shoulder rotation is useful for selective activation of the infraspinatus, no study has examined the influence of exercise position on axial shoulder rotation during shoulder external rotation (ER) exercises. Thus, this study investigated the muscle activity in the infraspinatus, posterior deltoid, and middle trapezius during shoulder ER exercises performed with and without controlled axial shoulder rotation in 2 different positions., Methods: Twenty healthy subjects performed prone external rotation (PER) exercises with and without pressure biofeedback and seated external rotation (SITER) exercises with and without posterior humeral head gliding. Muscle activity during each ER exercise was measured using surface electromyography., Results: Exercise strategy (P < .001) and position (P < .001) had a significant main effect on muscle activity in the infraspinatus and posterior deltoid. However, no significant interaction between strategy and position was observed. For muscle activity in the middle trapezius, strategy and position had a significant interaction effect (P = .014). Muscle activity in the infraspinatus increased significantly with the use of strategies to control axial shoulder rotation, whereas muscle activity in the posterior deltoid and middle trapezius decreased significantly. For all 3 muscles, greater activity was observed in the prone position than the seated position., Conclusion: We suggest that PER with pressure biofeedback can be useful to improve selective activation of the infraspinatus muscle while further eliciting infraspinatus muscle activity., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Introduction: Most surgical site infections after shoulder surgery are caused by Cutibacterium acnes. Topically applied benzoyl peroxide (BPO) has for years been used to decrease the skin load of C acnes in treatment of acne vulgaris. The purpose of this study was to examine this effect on bacterial colonization in patients subjected to elective shoulder surgery at different stages of the procedure., Methods: A total of 100 patients scheduled for primary elective open shoulder surgery were randomized to prepare either with BPO or according to local guidelines-with soap (control group). Four skin swabs were taken in a standardized manner at different times, before and after surgical skin preparation, 1 in dermis, and finally after the skin was sutured. Before skin incision, 5 punch biopsies (3 mm in diameter and maximum 4 mm deep) were retrieved spaced 2 cm apart in the planned skin incision. On culturing, quantification of C acnes was made by serial dilutions., Results: Men had a 5-fold higher amount of C acnes on untreated skin. Treatment with BPO considerably lowered this count (P = .0001) both before and after skin disinfection compared to the control group. This positive effect of BPO persisted until skin closure, the point at which some recolonization of C acnes had occurred, but to a higher degree in the control group (P = .040)., Conclusion: Preoperative BPO treatment of the shoulder may be an effective method to decrease bacterial skin load of C acnes from skin incision until wound closure., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: We aimed to evaluate the short-term outcomes of arthroscopic biceps rerouting (ABR) for the treatment of large to massive rotator cuff tears (LMRCTs)., Methods: A prospective evaluation of patients treated with ABR for the repair of LMRCTs was performed, with a minimum follow-up period of 18 months. Range of motion and functional outcomes (visual analog scale pain score, American Shoulder and Elbow Surgeons score, and Korean Shoulder Scale score) were assessed preoperatively and at final follow-up. Radiographs were used to evaluate the acromiohumeral interval (AHI). Magnetic resonance imaging was performed at 2 and 12 months postoperatively to examine the integrity of the repaired rotator cuff tendons., Results: Eighty patients who met the study criteria underwent ABR from March 2017 to January 2019 in our hospital. Of these patients, 61 could be evaluated ≥18 months after surgery. The average age of the enrolled patients was 64.5 years. The visual analog scale pain score decreased from 3.7 preoperatively to 1.6 at final follow-up (P = .019), the American Shoulder and Elbow Surgeons score improved from 60.0 to 85.2 (P < .001), and the Korean Shoulder Scale score improved from 64.3 to 85.3 (P = .001). Assessment of range of motion showed significant improvement in forward flexion (from 138° to 146°, P < .001), external rotation at 90° of abduction (from 80° to 85°, P = .037), and internal rotation (from spinal level 9 to spinal level 10, P = .015) from preoperatively to last follow-up. The AHI was 7.1 mm at baseline and improved significantly to 9.7 mm at 3 months postoperatively (P < .001). The mean AHI at last follow-up was only 9 mm, but this was still significantly better than the mean preoperative AHI (P < .001). Of the patients, 16 (26%) exhibited a retear of the repaired rotator cuff on magnetic resonance imaging at 12 months postoperatively. Male sex was the only significant risk factor for retear (P = .037)., Conclusion: ABR improved the functional and radiologic outcomes of patients with LMRCTs. The ABR technique can be a useful treatment option for LMRCTs., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate midterm outcomes of arthroscopic superior capsular reconstruction (SCR) using a decellularized porcine dermal xenograft in patients with massive, irreparable rotator cuff tears and to determine the influence of concomitant, repairable subscapularis tears., Methods: This is a retrospective study of 56 patients with a minimum 2-year follow-up. Preoperative and postoperative range of motion, American Shoulder and Elbow Surgeons score, Subjective Shoulder Value, and visual analog score for pain were measured. Postoperative data were collected at 3, 6, 12, 24, and 36 months., Results: Of the 56 patients who underwent arthroscopic SCR, there were 39 men and 17 women. The mean age at operation was 65 ± 9 years, and the mean follow-up was 34 ± 8 months. The mean preoperative American Shoulder and Elbow Surgeons improved from 41 ± 19 to 78 ± 18 at 24 weeks, to 86± 16 at 12 months, and to 90±9 at 24 months, P < .0001. Similarly, the mean preoperative Subjective Shoulder Value improved from 39 ± 17 to 74 ± 18 at 24 weeks, to 80 ± 18 at 12 months, and to 80 ± 11 at 24 months, P < .0001. The mean preoperative visual analog score improved from 6.5 ± 2.1 to 1.4 ± 2.2 at 24 weeks, to 0.7± 1.1 at 12 months, and to 0.2 ± 0.4 at 24 months, P < .0001. There were no differences in outcome scores between patients with intact vs. repaired subscapularis. Similarly, no statistically significant differences were found in forward flexion or external rotation after SCR between patients with an intact vs. repaired subscapularis. Failure of the SCR graft was observed on magnetic resonance imaging in 14 patients, 4 of whom opted for revision to reverse shoulder arthroplasty. Eleven patients were truly pseudoparalytic before surgery; in 5 cases, pseudoparalysis was reversed after SCR., Conclusions: SCR can alleviate pain and disability from irreparable rotator cuff tears and provide significant improvements in shoulder function; however, the xenograft technique resulted in inconsistent reversal of true pseudoparalysis. No difference was found between patients who required concomitant subscapularis repair vs. those who did not., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: There is currently disagreement among experts in the field of shoulder surgery when attempting to define the term "pseudoparalysis." Multiple surgical techniques to address this condition have been investigated; however, many studies have recruited heterogeneous patient populations and have used varying definitions of pseudoparalysis. This makes it difficult to compare outcomes among various techniques. To our knowledge, no previous study has surveyed international experts regarding the definition of pseudoparalysis using a questionnaire and video-based patient assessment. The purpose of this study was to evaluate the level of agreement among shoulder surgeons in defining and applying the term "pseudoparalysis." We hypothesized that inter-rater agreement for classifying patients as having pseudoparalysis would be poor., Methods: Members of the American Shoulder and Elbow Surgeons, the European Society for Surgery of the Shoulder and the Elbow, and our national shoulder and elbow society were surveyed on 2 occasions using an electronic questionnaire. All surgeons were asked to identify their preferred definition of pseudoparalysis from 1 of 4 options. The surgeons then viewed video examinations of 10 patients and labeled them as having pseudoparalysis or not. Inter-rater reliability and intrarater reliability were calculated as κ coefficients. The Pearson χ 2 test was used to detect associations between the preferred definition and demographic information., Results: A total of 246 surgeons responded to at least 1 survey. Overall inter-rater agreement on classifying patients as having pseudoparalysis based on video consultation showed a κ value of 0.59 (95% confidence interval [CI], 0.58-0.60). The same verbal definition was selected by 56.1% of surgeons. The surgeons were not internally consistent in their choice of definition, with intrarater reliability showing a κ value of 0.64 (95% CI, 0.48-0.81). Intrarater reliability for classifying patients as having pseudoparalysis was better, with a κ value of 0.78 (95% CI, 0.72-0.83). An association was observed between how surgeons defined pseudoparalysis and their age (P = .03), as well as their shoulder caseload percentage (P = .04)., Conclusion: Shoulder surgeons do not agree on how best to define pseudoparalysis of the shoulder. Inter-rater agreement based on video consultation was weak overall and improved with the elimination of an outlier video. Intrarater agreement was less frequent when selecting a preferred definition compared with classifying patients as having pseudoparalysis based on video examinations. Surgeons may rely less on explicit criteria and more on a conceptual framework when assigning a "pseudoparalytic" label. Care should be taken with use of the term "pseudoparalysis" in clinical outcome studies when there is clearly a lack of consensus among experts in defining this term., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Although massive rotator cuff tears occasionally lead to severe impairment of shoulder function, the criteria for losing the ability to elevate the arm are unclear. This study aimed to analyze the features of both tear size and 3-dimensional (3D) shoulder kinematics that correspond to the loss of the ability to elevate the arm in patients with large and massive rotator cuff tears., Methods: We prospectively enrolled patients with rotator cuff tears, including the supraspinatus and more than half of the subscapularis or more than two-thirds of the infraspinatus, without severe pain. A total of 13 patients (15 shoulders) were divided into 2 groups: 9 shoulders in the pseudoparesis (P) group and 6 shoulders in the non-pseudoparesis (NP) group. Fluoroscopic images were collected during active scapular-plane elevation, and 3D shoulder kinematics was analyzed using 2-dimensional-3D registration techniques. The radiographic findings and 3D kinematic results were compared between the groups. The correlation between tear size and 3D kinematics was also investigated., Results: The most superior position of the humeral head center was significantly higher in the P group (6.7 ± 3.0 mm in P group vs. 3.6 ± 1.3 mm in NP group, P = .0321). Superior migration, which was defined as the most superior position > 5 mm, was significantly more frequent in the P group (7 shoulders and 1 shoulder in the P and NP groups, respectively; P = .0201). Thoracohumeral external rotation was significantly smaller in the P group (16° ± 31° in P group vs. 91° ± 21° in NP group, P < .0001). The total tear size and the tear sizes of the anterior and posterior rotator cuffs were significantly correlated with the superior (r = 0.68, P = .0056), anterior (r = 0.68, P = .0058), and posterior (r = -0.80, P = .0004) positions of the humeral head center. The tear size of the posterior rotator cuff also tended to be correlated with glenohumeral external rotation (r = -0.48, P = .0719)., Conclusion: Anterior and posterior rotator cuff tears cause significant superior and anteroposterior translations of the humeral head, and posterior cuff tears may lead to loss of glenohumeral external rotation. With these abnormal kinematics, superior migration and loss of thoracohumeral external rotation were identified as features of pseudoparesis., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Hypothesis: College pitchers with increased external rotation gain (ERG) produce increased medial elbow torque (elbow stress) whereas those with reduced total rotational range of motion (ROM) have reduced medial elbow torque during pitching., Methods: Pitchers were recruited from 3 college baseball teams. Players with prior injury or on pitching restrictions because of pain were excluded. Players were evaluated within 2 weeks before their first game of the season. Pitchers completed an intake survey, and shoulder and arm measurements were taken. Pitchers were fitted with a baseball sleeve that included a sensor at the medial elbow. The sensor calculated elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. After adequate warm-up, pitchers threw 5 fastballs in a standardized manner off the mound at game-speed effort. The primary outcome evaluated the relationship between shoulder ROM and medial elbow torque. Additional outcomes evaluated pitcher characteristics and demographic characteristics in the context of shoulder ROM., Results: Twenty-eight pitchers were included in the preseason analysis. The average age and playing experience were 20.1 years (standard deviation [SD], 1.3 years) and 15.3 years (SD, 1.8 years), respectively, with 2.5 years (SD, 1.2 years) playing at collegiate level. The dominant shoulder showed decreased internal rotation and increased external rotation (ER) relative to the nondominant side (P < .001). The average glenohumeral internal rotation deficit and ERG were 11.3° (SD, 9.87°) and 5.71° (SD, 8.8°), respectively. ERG ≥ 5° was a significant predictor of elbow stress during pitching (47.4 Nm [SD, 0.7 Nm] vs. 45.1 Nm [SD, 0.6 Nm], P = .014). Univariate associations showed that each additional degree of ER resulted in increased elbow torque (β estimate, 0.35 ± 0.06 Nm; P = .003). Conversely, decreased medial elbow torque was found in pitchers with reduced shoulder ROM (glenohumeral internal rotation deficit ≥ 20°: 43.5 Nm [SD, 1.1 Nm] vs. 46.6 Nm [SD, 0.5 Nm], P = .011; loss of total rotational ROM ≥ 5°: 43.6 Nm [SD, 1.1 Nm] vs. 46.6 Nm [SD, 0.5 Nm], P = .013) and in those with greater arm length (P < .05)., Conclusions: College pitchers with increased ER produce greater medial elbow torque during the pitching movement. Each degree of increased ER was found to correlate with increased elbow torque and ball velocity. On the contrary, arm length and reduced shoulder ROM were associated with reduced medial elbow torque. This study suggests that increased ER in pitchers is associated with greater elbow stress during pitching., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Humeral head-preserving procedures may be needed for chronic neglected shoulder dislocation because the presenting age of the patient is often reported to be less than 45 years. The aim of this systematic review was to evaluate the results of the various head-preserving procedures for chronic anterior dislocation (CAD) and chronic posterior dislocation (CPD). This review also aimed to evaluate the results of conservative neglect for CAD., Methods: PubMed, Embase, and Cochrane library databases were queried for studies that reported on results of head-preserving procedures for CAD or CPD and for studies that reported on the results of conservative neglect for CAD. Case reports, review articles, acute dislocations, and fracture-dislocations were excluded. The results of the different techniques were pooled for further evaluation., Results: Seventeen studies were selected for qualitative analysis. These were further subdivided into 9 studies for the CAD group and 11 studies for the CPD group. In the CAD intervention group, 53 shoulders in 7 studies were managed by 5 different head-preserving techniques. The choice of procedure to stabilize the shoulder after open reduction varied between coracoid transfer, capsulolabral repair, remplissage, and Putti-Platt procedure and acromiohumeral K-wire fixation. High resubluxation rates and early arthrosis were reported after open reduction techniques for CAD. In the CAD conservative group, 8 shoulders in 2 studies were managed by conservative methods. In the CPD group, the 2 most common techniques, McLaughlin or modified McLaughlin and bone grafting, were used to treat 74 shoulders in 7 studies and showed good functional outcomes., Conclusion: The choice of open reduction and stabilization technique for CAD was highly variable between the different studies and led to a wide variation in the reported outcomes with a high number of complications such as resubluxation and early arthrosis. The conservative treatment of CAD led to poor functional results. The choice of treatment for CPD was mostly between 2 techniques-McLaughlin and modified McLaughlin reconstruction or the bone graft reconstruction-and they consistently led to good functional outcomes with less complications., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Decreased glenohumeral (GH) horizontal adduction range of motion (ROM) among baseball pitchers has been associated with the development of various shoulder and elbow pathologies. No research has examined how this tightness may affect the forces placed on the shoulder and elbow during the pitching motion., Methods: Fifty-five asymptomatic National Collegiate Athletic Association Division I baseball pitchers participated. Twenty-five participants had -10° or less horizontal adduction ROM in their throwing shoulder. The remaining 30 participants had greater than -10° of horizontal adduction. A digital inclinometer was used to measure GH horizontal adduction, internal rotation, and external rotation ROM while in 90° of shoulder abduction. Forces produced in the throwing shoulder and elbow were assessed with a 3-dimension, high-speed video capture system and based on the sum of angular momenta of the kinetic chain segments around the center of gravity. Separate 2-tailed t tests were run to determine significant differences between groups (P < .05)., Results: Both groups presented with significant bilateral differences in their total arcs of motion (P < .04). This suggests that the loss of horizontal adduction in these groups was at least partially due to soft tissue tightness. There were no significant between-group differences for shoulder external rotation torque or shoulder and elbow distraction (P > .10). The restricted ROM group had significantly more shoulder abduction torque (P = .04), shoulder horizontal abduction torque (P = .004), elbow flexion torque (P = .002), and elbow valgus torque (P = .02) compared with the control group., Conclusions: These results demonstrate that collegiate pitchers with -10° or less of horizontal adduction ROM in their throwing shoulder create significantly more shoulder abduction and horizontal abduction torque, as well as more elbow flexion and valgus torque, during the pitching motion than those with more ROM., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Cutibacterium acnes (C acnes) is a mysterious member of the shoulder microbiome and is associated with chronic postoperative complications and low-grade infections. Nevertheless, it is unclear whether it represents a contaminant or whether it accounts for true infections. Because it can persist intracellularly in macrophages at several body sites, it might in fact be an intra-articular commensal of the shoulder joint., Methods: In 23 consecutive, otherwise healthy patients (17 male, 6 female; 58 years) who had no previous injections, multiple specimens were taken from the intra-articular tissue during first-time arthroscopic and open shoulder surgery. The samples were investigated by cultivation, genetic phylotyping, and immunohistochemistry using C acnes-specific antibodies and confocal laser scanning microscopy., Results: In 10 patients (43.5%), cultures were C acnes-positive. Phylotype IA1 dominated the subcutaneous samples (71%), whereas type II dominated the deep tissue samples (57%). Sixteen of 23 patients (69.6%) were C acnes-positive by immunohistochemistry; in total, 25 of 40 samples were positive (62.5%). Overall, 56.3% of glenohumeral immunohistochemical samples, 62.5% of subacromial samples, and 75% of acromioclavicular (AC) joint samples were positive. In 62.5% of the tested patients, C acnes was detected immunohistochemically to reside intracellularly within stromal cells and macrophages., Discussion: These data indicate that C acnes is a commensal of the human shoulder joint, where it persists within macrophages and stromal cells. Compared with culture-based methods, immunohistochemical staining can increase C acnes detection. Phylotype II seems to be most prevalent in the deep shoulder tissue. The high detection rate of C acnes in osteoarthritic AC joints might link its intra-articular presence to the initiation of osteoarthritis., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Painful shoulders create a substantial socioeconomic burden and significant diagnostic challenge for shoulder surgeons. Consensus with respect to the anatomic location of sensory nerve branches is lacking. The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches (ABs) (1) innervating the shoulder joint and (2) the distribution of sensory receptors about its capsule and bursae., Materials and Methods: Four electronic databases were queried, between January 1945 and June 2019. Thirty original articles providing a detailed description of the distribution of sensory receptors about the shoulder joint capsule (13) and its ABs (22) were reviewed., Results: The suprascapular, lateral pectoral, axillary, and lower subscapular nerves were found to provide ABs to the shoulder joint. The highest density of nociceptors was found in the subacromial bursa. The highest density of mechanoreceptors was identified within the insertion of the glenohumeral ligaments. The most frequently identified innervation pattern comprised 3 nerve bridges (consisting of ABs from suprascapular, axillary, and lateral pectoral nerves) connecting the trigger and the identified pain generator areas rich in nociceptors., Conclusion: Current literature supports the presence of a common sensory innervation pattern for the human shoulder joint. Anatomic studies have demonstrated that the most common parent nerves supplying ABs to the shoulder joint are the suprascapular, lateral pectoral, and axillary nerves. Further studies are needed to assess both the safety and efficacy of selective denervation of the painful shoulders, while limiting the loss of proprioceptive function., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: There is an increasing trend toward the use of reverse total shoulder arthroplasty (RTSA) over stemmed hemiarthroplasty (HA) for the management of proximal humeral fractures. There are limited data available comparing the revision rates for RTSA and HA in the setting of a fracture. The aim of this study was to compare the revision rates for RTSA and HA when used for the treatment of a fracture and to analyze the effect of demographics and prosthesis fixation on these revision rates., Methods: Data obtained from the Australian Orthopaedic Association National Joint Replacement Registry from April 16, 2004, to December 31, 2017, included all procedures for primary diagnosis proximal humeral fracture. The analyses were performed using Kaplan-Meier estimates of survivorship and hazard ratios from Cox proportional hazards models., Results: Over the study period, there were 3049 (51%) RTSA and 2897 (49%) HA procedures. The cumulative percent revision rate at 9 years was lower for the RTSA than for the HA: 7.0% (95% confidence interval [CI], 4.8-10.1) compared with 11.7% (95% CI, 10.3-13.2). Between 0 and 6 months, the HA had a significantly lower revision rate than the RTSA (hazard ratio, 0.50; 95% CI, 0.34-0.72; P < .001). Between 6 month and 3 years, the HA had a significantly higher revision rate. For the RTSA, males have a significantly higher rate of revision compared with females. There is a higher rate of early revision due to instability in younger persons (55-64) and males. For both RTSA and HA, cemented prostheses have lower revision rates compared with cementless prostheses., Conclusions: RTSA has a significantly lower revision rate compared with HA for the treatment of proximal humeral fractures in females. Younger patients (<65) and males are at risk of early revision secondary to instability. In these patient groups, either alternatives to RTSA or further attention to fixation of tuberosities and shoulder rehabilitation may be indicated., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The purpose of this study was to investigate the clinical efficacy of the "suspension bridge" external fixation technique for the treatment of proximal humeral fractures with or without soft tissue defects and infection, as well as postoperative revision., Methods: From August 2013 to June 2018, 9 patients with proximal humeral fractures were selected. There were 5 males and 4 females, with an average age of 55.2 years (range: 32-74 years). Five patients were diagnosed with acute fractures (soft tissue defects in 2 patients). Of these patients, 1 patient was diagnosed with a fracture of the anatomic neck, 2 patients with 3-part fractures, and 2 patients with 4-part fractures. Internal fixation failure occurred in 4 patients, who needed revision surgery. Of these 4 patients, 1 patient was diagnosed with an anatomic neck fracture and 3 patients with 4-part fractures before surgery. Postoperative plate and screw fixation failure was the main cause of revision. One patient had an accompanying skin defect, and 1 had an infection. The "suspension bridge" external fixation technique was used to treat the fractures in the revision surgeries., Results: The operative time was 84.1 minutes (range: 63-120 minutes), and the blood loss was 224.4 mL (range: 140-320 mL). The follow-up period was 35.1 months (range: 16-72 months). All fractures unioned, with an average unioning time of 12.7 weeks (range: 8-16 weeks). At the final follow-up, the flexion was 131.8° (range 108°-152°), extension 39.9° (range 32°-47°), abduction 128.6° (range 110°-150°), internal rotation 43.9° (range 34°-55°), and external rotation 60.7° (range 46°-72°); the mean visual analog scale score for pain was 1.3 (range 0-3), and the mean Neer score was 87.4 points (range 75-98 points). Efficacy was assessed as excellent in 4 patients, good in 3 patients, and acceptable in 2 patients; the excellent or good rate was 77.8%. No adverse events, such as postoperative infection, fixation failure, and nonunion, occurred during the follow-up., Conclusion: The "suspension bridge" external fixation technique is an effective method for the treatment of proximal humerus fractures, and it can also be used for the treatment of skin defects and infections., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Total shoulder arthroplasty (TSA) is commonly performed for shoulder osteoarthritis (OA). Uncemented metal-backed (MB) glenoid components were introduced in an attempt to avoid glenoid loosening. New Zealand and Australian Joint Registry studies have shown significantly higher revision rates when uncemented MB glenoids are used. We used the New Zealand Joint Registry (NZJR) to compare all-cause revision rates and functional scores for TSA and investigated the trends of glenoid fixation used in New Zealand., Methods: The NZJR was accessed for all primary TSA undertaken for OA from January 2000 to December 2017. Patient demographics were collated. All-cause revision rates were reported as rate per 100 component-years. Analysis was repeated excluding the uncemented SMR L2 glenoid (LimaCorporate), as it was a potential confounder. Kaplan-Meier survival analysis was performed. Oxford Shoulder Scores at both 6 months and 5 years were analyzed., Results: A total of 2613 TSAs were performed for OA during the study period, representing 85.0% of all TSAs in New Zealand. Overall, 62.1% of the patients were female. In addition, 69.6% of glenoids were cemented and 30.4% uncemented. The most common uncemented MB glenoid was SMR 86.6% (LimaCorporate), and cemented was Global (DePuy) 49.8%. The revision rate for TSA with uncemented glenoids was significantly higher at 2.03 compared with cemented at 0.41 per 100 component-years (P < .001). Hazard ratio 5.0 for revision of uncemented glenoids. No significant difference was found in Oxford Scores at 6 months (39.7 vs. 40.3, P = .13) or 5 years (42.1 vs. 42.8, P = .22). The most common mode of failure was glenoid loosening in cemented glenoids (44.4%), and component failure in uncemented (34.8%). Revision for rotator cuff, deep infection, and instability were comparable between groups. When excluding SMR L2, uncemented MB glenoid all-cause revision rates remained significantly higher than cemented (1.42 vs. 0.41 per 100 component-years, P < .001). SMR L1 uncemented MB glenoids had a higher revision rate than the non-SMR uncemented glenoids (1.61 vs. 0.18 per 100 component-years, P = .009). Uncemented glenoid use peaked in New Zealand in 2011 at 46.7% of TSAs but declined to 20.1% in 2017., Conclusions: In the NZJR, primary TSAs undertaken for OA have a significantly higher all-cause revision rate when the glenoid component is uncemented. Uncemented glenoids have a 5.0 times higher revision rate. Excluding SMR L2 glenoids from the analysis, the significantly higher revision rate remained for uncemented glenoids. These data reaffirm that uncemented MB glenoids are associated with higher revision rates., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)