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Background: Establishing patient-matched cohorts can be a valuable technique for minimizing selection bias in outcomes research pertaining to shoulder arthroplasty. This systematic review evaluated the variety and inconsistency with which matching techniques are employed in matched studies assessing outcomes following shoulder arthroplasty., Methods: The PubMed, EMBASE, and Cochrane computerized databases were queried from their inception through December 2023 to identify clinical outcome studies of shoulder arthroplasty that employed a matched study design. Study quality was assessed via the Methodological Index for Non-Randomized Studies criteria. Matching techniques, covariates included, and covariate justification were aggregated., Results: Among 110 studies encompassing 483,738 shoulder arthroplasties, 82 (74.6%) studies employed direct matching and 28 (25.5%) employed propensity score matching. Seventy-four distinct covariates were used in at least one study, with 86 unique combinations of covariates employed. Studies used a median of 4 covariates (range 1-27). The most common covariates were age (94.5%), sex (89.1%), body mass index (26.4%), smoking (19.1%), and follow-up duration (19.1%). Only 16 (14.6%) studies reported justification for the covariates included., Conclusions: There are marked methodological discrepancies among studies using covariate matching methods in the shoulder arthroplasty literature. Future matched studies in shoulder arthroplasty should provide justification for included covariates and properly account for matching in their statistical analyses to enhance the validity of study findings. When patient matching is deemed appropriate, key variables to consider for matching may include patient age, sex, comorbidity burden and, when analyzing multiple clinical conditions, surgical indication., (Copyright © 2025. Published by Elsevier Inc.)

Background: Glenoid version is a critical anatomic parameter relied upon by many surgeons to inform preoperative planning for shoulder arthroplasty. Advancements in imaging technology have prompted measurements of glenoid version on various imaging modalities with different techniques. However, discrepancies in how glenoid version is measured within the literature have not been well characterized., Methods: A literature search was performed by querying PubMed, EMBASE, CINAHL, and Cochrane computerized databases from their inception through December 2023 to identify studies that assessed the relationship between preoperative glenoid version and at least one clinical or radiologic outcome following shoulder arthroplasty. Study quality was assessed via the Methodologic Index for Nonrandomized Studies criteria. Imaging modalities and techniques for measuring glenoid version, along with their association with clinical outcomes, were aggregated., Results: Among 61 studies encompassing 17,070 shoulder arthroplasties, 27 studies (44.3%) described explicitly how glenoid version was measured. The most common imaging modality to assess preoperative glenoid version was computed tomography (CT) (63.9%), followed by radiography (23%); 11.5% of studies used a combination of imaging modalities within their study cohort. Among the studies using CT, 56.5% utilized two-dimensional (2D) CT, 41.3% utilized three-dimensional (3D) CT, and 2.2% used a combination of 2D and 3D CT. The use of 3D CT increased from 12.5% of studies in 2012-2014 to 25% of studies in 2018-2020 to 52% of studies in 2021-2023 (p trend  = 0.02). Forty-three (70.5%) studies measured postoperative version, most commonly on axillary radiograph (22 [51.2%]); 34.9% of these studies used different imaging modalities to assess pre- and postoperative version., Conclusions: This systematic review revealed marked discrepancies in how glenoid version was measured and reported in studies pertaining to shoulder arthroplasty. A temporal trend of increased utilization of 3D CT scans and commercial preoperative planning software was identified. Improved standardization of the imaging modality and technique for measuring glenoid version will enable more rigorous evaluation of its impact on clinical outcomes., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Patients who rely on their upper extremities for ambulation, or upper extremity ambulators (UEAs), place considerable stress on their shoulders through the use of assistive devices like walkers, crutches, canes, and wheelchairs. It has been postulated that UEAs may be at increased risk for complications following shoulder arthroplasty. This study aimed to systematically review the literature related to (1) patient-reported outcomes measures (PROMs), (2) functional outcomes, and (3) complications in UEAs who undergo shoulder arthroplasty., Methods: A systematic review of the PubMed/MEDLINE, Embase, and Cochrane databases was performed to identify studies reporting clinical outcomes of shoulder arthroplasty in UEAs. Patient demographics, clinical characteristics, patient-reported outcomes measures, radiographic outcomes, and postoperative range of motion were collected and compared to control patients (ie bipedal ambulators) from the constituent studies., Results: A total of eight studies evaluating 248 UEA cases and 206 control cases were included for review. Ambulatory assistive devices utilized by UEAs included walkers (39%), wheelchairs (38%), canes (22%), and a crutch (<1%). Among UEA cases, 197 (79%) reverse total shoulder arthroplasty (TSA), 37 (15%) anatomic TSA, and 14 (6%) hemiarthroplasty were performed. Overall, patients exhibited significant improvements in mean American Shoulder and Elbow Surgeons scores, Constant-Murley scores, Simple Shoulder Test scores, and Visual Analog Scale scores postoperatively. Among 3 studies that included comparison with control groups of bipedal ambulators, no significant differences in outcomes were identified. The overall clinical complication rate was 17% for UEAs compared to 9.1% for controls. The rate of revision surgery was 7.7% for UEAs and 4.9% for bipedal ambulators., Conclusions: UEAs experience satisfactory pain relief, functional improvements, and good subjective outcomes following shoulder arthroplasty. However, complication and revision rates are higher compared to those for bipedal ambulators, and the majority of UEAs undergo reverse shoulder arthroplasty compared to anatomic TSA., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Patients undergoing reverse total shoulder arthroplasty (rTSA) for rotator cuff arthropathy may present with an external rotation (ER) lag due to posterior rotator cuff insufficiency. As a result, the addition of a latissimus dorsi (LD) tendon transfer in combination with rTSA has become increasingly utilized. Initial descriptions of LD tendon transfer involved rerouting of the LD tendon posterior to the long head of the triceps tendon. However, more recent techniques involve rerouting the LD tendon anterior to the long head of the triceps tendon via the deltopectoral approach utilized for rTSA. The purpose of this cadaveric study was to assess the biomechanical effect on ER force of LD tendon transfer anterior vs. posterior to the long head of the triceps tendon in combination with rTSA., Methods: Eight fresh frozen cadaveric shoulders were utilized. A shoulder fellowship trained orthopedic surgeon performed rTSA in each specimen. The rotator cuff tendon attachments were cut to simulate a massive rotator cuff tear. The LD tendon was transferred to the greater tuberosity first anterior to the long head of the triceps, and then posterior to the long head of the triceps. The specimens underwent biomechanical testing for each condition using an established cadaveric shoulder simulator with 6 degrees of freedom for glenohumeral joint motion., Results: Both anterior and posterior LD tendon transfers successfully achieved ER of the humerus when force was applied to the LD tendon. Posterior LD tendon transfer resulted in less required force to achieve ER of the arm throughout range of motion compared to anterior LD tendon transfer (33.4 N vs. 48.6 N, P < .001), which was maintained irrespective of glenohumeral abduction angle. Loading of the long head of the triceps tendon was associated with significantly increased force required for generation of ER only in the anterior LD tendon transfer condition (48.6 N loaded vs. 39.4 N unloaded; P < .001)., Conclusion: LD tendon transfer posterior to the long head of the triceps resulted in more efficient humeral ER movements in the setting of rTSA, irrespective of degree of shoulder abduction. Our results also demonstrate that long head of the triceps tension results in decreased efficiency of the LD tendon transfer when performed anterior to the long head of the triceps. While technically more difficult, transfer of the LD tendon posterior to the long head of the triceps provides a mechanical advantage that may improve clinical outcomes in patients with rTSA lacking ER., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Massive proximal humeral bone loss (PHBL) poses a technical challenge during reverse shoulder arthroplasty (RSA). Surgical treatment strategies include allograft-prosthetic composite (APC) reconstructions, endoprostheses, and other reverse shoulder arthroplasty constructs; however, there is a paucity of literature summarizing the outcomes and complications unique to this complex patient population. This study aimed to systematically review the literature to evaluate (1) patient-reported outcome measures, (2) functional outcomes, and (3) complications according to surgical treatment strategy for patients with massive PHBL who undergo primary or revision shoulder arthroplasty., Methods: A systematic review of the PubMed/MEDLINE, Embase, and Cochrane databases was performed to identify studies reporting clinical outcomes and complications of reverse shoulder arthroplasty in patients with significant PHBL. Methodological quality was assessed for included studies. Patient-reported outcome measures, radiographic outcomes, and postoperative functional outcomes were collected., Results: Eleven studies evaluating clinical outcomes and complications of reverse shoulder arthroplasty in the setting of PHBL comprising 277 patients were included for review. The mean age was 66 years (range, 60-79 years). American Shoulder and Elbow Surgeons score, Visual Analog Scale, and range of motion were the most common outcomes collected, and patients exhibited significant improvements in mean scores postoperatively. Of the types of prostheses reported, there were 155 reverse shoulder arthroplasty (RSA) with allograft-prosthetic composite (APC) reconstructions, 48 proximal humeral replacement (PHR) endoprostheses, 41 RSA, 15 custom RSA, and 2 RSA with fibular strut allografts. The overall pooled complication rate was 30.1% (82/272) with revision/reoperation as the most common complication at 21% (57/272). The overall complication rate for RSA-APC reconstructions was 51% (79/155). The overall complication rate for PHR endoprostheses was 64.6% (31/48). Revision/reoperation rates were the most complication for both RSA-APC and PHR endoprostheses with rates of 20% and 31.3%, respectively., Conclusions: Treatment by APC reconstruction is the most common surgical technique described in the setting of massive PHBL. While shoulder arthroplasty can yield acceptable results for patients with substantial PHBL, such patients are at increased risk for complications and revision surgery., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Patients who undergo total shoulder arthroplasty usually have excellent long-term outcomes. However, a subset of patients is diagnosed with a prosthetic joint infection (PJI) requiring revision procedures and prolonged recovery. The purpose of this study was to evaluate rates of recurrent shoulder PJI in patients undergoing débridement, antibiotics, and implant retention (DAIR), single-stage revision, and 2-stage revision. We also sought to compare outcomes and complications across procedures., Methods: Retrospective chart review was conducted for patients diagnosed with PJI after primary shoulder arthroplasty between January 2010 and August 2021. Patients were included if they underwent treatment with DAIR, single-stage revision, or 2-stage revision. Demographic information, surgical details, complications, laboratory data, postoperative antibiotic regimen, and infectious pathogen were collected. Postoperative patient-reported outcomes were collected: American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, Single Assessment Numeric Evaluation, Shoulder Activity Scale, and PROMIS Upper Extremity. Chi-square, t test, and 1-way analysis of variance were used as appropriate to evaluate each factor., Results: Sixty-five patients were included in the study, 26% treated with DAIR, 9% treated with single-stage revision, and 65% treated with 2-stage revision. There were no significant differences in patient comorbidities. Patients undergoing DAIR were diagnosed significantly earlier than those undergoing single- and 2-stage revision procedures (12.6 ± 22.9 months vs. 49.6 ± 48.4 vs. 25.0 ± 26.6, P = .010). Recurrent PJI was noted in 23.1% of patients: 29.4% of DAIR patients, no single-stage patients, and 23.8% of 2-stage patients (P = .330). Patients undergoing 2-stage revision with treatment failure had a significantly higher Elixhauser Comorbidity Index (0.2 ± 3.7 vs. 3.7 ± 3.9, P = .027). There was no significant difference in patient-reported outcomes across groups., Conclusion: Patients undergoing treatment of shoulder PJI with DAIR did not have an increased rate of reinfection compared with single-stage and 2-stage revision procedures. Patients treated with DAIR were diagnosed with PJI significantly earlier than those undergoing single-stage and 2-stage revision procedures. There was no difference in complication rates between groups. This information adds to the body of work detailing outcomes after DAIR for shoulder PJI and provides encouraging data for use in this patient population. Future studies with a larger sample size may be conducted to further investigate specific pathogens, infection timelines, and antibiotic regimens that reduce the risk of treatment failure., (Copyright © 2024. Published by Elsevier Inc.)

Background: Accurate and rapid identification of implant manufacturer and model is critical in the evaluation and management of patients requiring revision total shoulder arthroplasty (TSA). Failure to correctly identify implant designs in these circumstances may lead to delay in care, unexpected intraoperative challenges, increased morbidity, and excess health care costs. Deep learning (DL) permits automated image processing and holds the potential to mitigate such challenges while improving the value of care rendered. The purpose of this study was to develop an automated DL algorithm to identify shoulder arthroplasty implants from plain radiographs., Methods: A total of 3060 postoperative images from patients who underwent TSA between 2011 and 2021 performed by 26 fellowship-trained surgeons at 2 independent tertiary academic hospitals in the Pacific Northwest and Mid-Atlantic Northeast were included. A DL algorithm was trained using transfer learning and data augmentation to classify 22 different reverse TSA and anatomic TSA prostheses from 8 implant manufacturers. Images were split into training and testing cohorts (2448 training and 612 testing images). Optimized model performance was assessed using standardized metrics including the multiclass area under the receiver operating characteristic curve (AUROC) and compared with a reference standard of implant data from operative reports., Results: The algorithm classified implants at a mean speed of 0.079 seconds (±0.002 seconds) per image. The optimized model discriminated between 8 manufacturers (22 unique implants) with AUROCs of 0.994-1.000, accuracy of 97.1%, and sensitivities between 0.80 and 1.00 on the independent testing set. In the subset of single-institution implant predictions, a DL model identified 6 specific implants with AUROCs of 0.999-1.000, accuracy of 99.4%, and sensitivity >0.97 for all implants. Saliency maps revealed key differentiating features across implant manufacturers and designs recognized by the algorithm for classification., Conclusion: A DL model demonstrated excellent accuracy in identifying 22 unique TSA implants from 8 manufacturers. This algorithm may provide a clinically meaningful adjunct in assisting with preoperative planning for the failed TSA and allows for scalable expansion with additional radiographic data and validation efforts., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Recent advances in implant technology have allowed for modular or platform humeral stem insertion during initial anatomic total shoulder arthroplasty (TSA). These systems allow for humeral stem retention during conversion to reverse TSA (RTSA). However, some patients still require humeral stem revision when undergoing revision to RTSA. The purpose of this study was to evaluate the association between patient-specific factors and radiographic parameters with humeral stem revision vs. retention during conversion from TSA to RTSA., Methods: Retrospective chart review was conducted for patients who underwent a revision TSA to RTSA between January 2010 and May 2022 at a single institution. Patients were included if their prosthesis included a convertible humeral stem. Patient demographic information, surgical details, and postoperative outcomes and complications were collected. Radiographic parameters were measured by 2 graders on radiographs taken prior to the revision procedure. The need for humeral stem revision and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores (preoperative and 2 years) were also noted. Statistical analysis was performed using chi-square test for categorical variables and t test for continuous variables., Results: One hundred seven patients were included, with 52 undergoing humeral stem revision. Patients were revised an average of 51.0 ± 54 months after primary TSA. Younger patient age (63.6 vs. 68.5 years, P = .017) and use of a lateralized glenosphere (1.6 mm vs. 0.4 mm, P < .001) were significantly associated with need for humeral stem revision. Glenoid to humeral head cut distance (28.3 mm vs. 26.3 mm, P = .076) approached significant association with the need for humeral stem revision. All other measurements were not associated with the need for humeral stem revision. Improvement of ASES scores at 2 years' follow-up was higher in the nonrevised group (increase of 33.4 points) than the revision group (23.3), but this did not reach significance (P = .149). Estimated blood loss and surgical time were significantly higher in the stem revision group than the non-revised group (P = .048 and P < .001, respectively)., Conclusion: Younger patients and those receiving a lateralized glenosphere were more likely to undergo humeral stem revision during conversion from TSA to RTSA. Glenoid to the humeral head cut distance should be studied further as a potential indication for humeral stem revision, as it correlates with the space available for a revision implant. This information can guide surgeons with preoperative planning for a revision arthroplasty., (Copyright © 2023. Published by Elsevier Inc.)

Background: The concordance between preoperative synovial fluid cultures and intraoperative tissue cultures for identifying pathogenic microorganisms in shoulder periprosthetic joint infection (PJI) remains poorly understood. The purpose of our study was to examine the diagnostic accuracy of positive synovial fluid culture results in early pathogen identification for shoulder PJI., Methods: A total of 35 patients who met the Musculoskeletal Infection Society criteria for PJI following primary anatomic or reverse arthroplasty and the study inclusion criteria were identified retrospectively from a single institution (multiple surgeons) from January 2011 to June 2021. The inclusion criteria required a positive preoperative intra-articular synovial fluid sample within 90 days analyzed within the same institution and intraoperative tissue cultures at the time of arthrotomy. Concordance was determined when the organism(s) identified from the aspirate correlated with the intraoperative specimens., Results: Overall concordance was identified in 28 of 35 patients (80%), with similar concordance for anatomic (21 of 24, 88%) and reverse (7 of 11, 64%) shoulder arthroplasties (P = .171). Culture discordance occurred in 7 of 35 patients (20%): of these, 5 (14%) had no corresponding intraoperative culture growth whereas 2 (6%) had polymicrobial intraoperative cultures. Monomicrobial Cutibacterium acnes PJI cases were the most common (24 of 35, 69%) and had an overall concordance rate of 79%. Of 5 discordant C acnes patients, 2 had polymicrobial intraoperative cultures and 3 had negative intraoperative culture results; all the patients with negative intraoperative culture results had received antibiotics between the time of aspiration and surgery. Considered separately, concordance in patients who had a positive aspirate finding for C acnes and did not receive antibiotics prior to surgery was 19 of 21 (90%), with a sensitivity of 100% (95% confidence interval, 82%-100%) and a corresponding positive predictive value of 0.91 (95% confidence interval, 58%-93%)., Conclusion: Preoperative positive aspiration culture results demonstrated favorable sensitivity and specificity when compared with intraoperative tissue cultures in identifying pathogenic microorganisms in shoulder PJI patients. These findings are congruent with literature from hip and knee arthroplasty. Ultimately, confidence in the accuracy of positive preoperative aspiration culture results in shoulder PJI may facilitate the development of early, targeted treatment strategies while directing patient expectations and risk., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The US Food and Drug Administration (FDA) oversees medical device regulation and oversight in the United States, and the majority of shoulder arthroplasty devices are cleared via the 510(k) pathway, in which a device demonstrates "substantial equivalence" to a previously cleared predicate. The purpose of this study was to determine an interconnected ancestral network of shoulder arthroplasty devices and determine equivalency ties to devices subsequently recalled by the FDA for design-related issues., Methods: The FDA 510(k) database was used to identify all legally marketed shoulder arthroplasty devices from May 28, 1976, to July 1, 2021. Direct predicate information obtained via clearance summary documents associated with each device was used to generate an ancestral genealogy network for all shoulder arthroplasty devices cleared between July 1, 2020, and July 1, 2021. FDA design recalls were analyzed, and the number of descendant devices was calculated for each recalled device., Results: An evaluation of all 476 510(k) premarket notification pathway-cleared shoulder devices since 1976 identified 0-313 descendant devices for each. Eighty of these devices (16.8%) have since been recalled, of which 10 recalls were directly related to implant design issues. Furthermore, among 29 of the most recently cleared devices (July 1, 2020-July 1, 2021), 16 (55.2%) claim predicates devices that have subsequently been withdrawn from the market because of design-related failures., Conclusions: Shoulder arthroplasty devices are linked together via an interconnected FDA 510(k) equivalency approval network dating back to 1976 despite substantive changes in material specifications and device design, many of which have since been recalled. Many of the cleared modern devices claim predicates based on subsequently recalled prostheses., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Dynamic anterior shoulder stabilization (DAS) with Bankart repair is a recently described stabilization technique thought to be more robust than an isolated Bankart repair while avoiding many coracoid transfer-related complications and technical demands. DAS involves transfer of the long head biceps through a subscapularis split to the anterior glenoid to create a sling effect. We hypothesize that DAS with Bankart repair will restore anterior stability in a human-cadaveric model with subcritical (15%) glenoid bone loss., Methods: Eight cadaveric shoulders were tested using an established shoulder simulator to record glenohumeral translations with an accuracy of ±0.2 mm. Shoulders were tested in 5 states-intact soft tissues, Bankart defect with 15% bone loss, isolated Bankart repair, DAS with Bankart repair, isolated DAS, and Latarjet. A 45 N anterior force was applied through the pectoralis major tendon, and translation of the humeral head was recorded and compared with repeated measures analysis of variance., Results: The anterior translation in the intact (native) glenoid was 4.7 mm at neutral position and 4.6 mm at 45° external rotation. Anterior translation significantly increased after introducing a Bankart defect with 15% glenoid bone loss to 9.1 mm (neutral, P = .002) and 9.5 mm (45° external rotation, P < .001). All repair conditions showed a significant decrease in anterior translation relative to Bankart defect. DAS with Bankart repair decreased anterior translation compared with the Bankart defect: 2.7 mm (neutral, P < .001) and 2.1 mm (45° external rotation, P < .001). DAS with Bankart repair significantly decreased anterior translation compared with the isolated Bankart repair (2.7 mm vs. 4.7 mm, P = .023) and the isolated DAS (2.7 mm vs. 4.3 mm, P = .041) in neutral position. The Latarjet procedure resulted in the greatest reduction in anterior translation compared with the Bankart defect: 1.2 mm (neutral, P < .001) and 1.9 mm (45° external rotation, P < .001)., Conclusions: DAS with Bankart repair is a viable alternative to restore anterior glenohumeral stability with a 15% glenoid defect at a greater degree than either DAS or Bankart repair alone. The Latarjet procedure was the most effective in reducing anterior translation but restrained the anterior translation significantly more than the native glenoid., (Copyright © 2022. Published by Elsevier Inc.)

Background and Hypothesis: Arthroscopic rotator cuff repair surgery is one of the most common shoulder procedures performed in the United States. Although several studies have shown considerable symptomatic relief in the short term following surgery, a relatively high rate of recurrent defects has led surgeons to question the long-term durability of this operation. We hypothesized that outcomes at a minimum of 15 years of follow-up in patients who underwent all-arthroscopic rotator cuff repair would be maintained and would remain significantly improved compared with the preoperative status., Methods: All-arthroscopic rotator cuff repairs were performed in 193 patients from 2003 to 2005. Patient-reported outcomes were collected preoperatively and at 1, 2, 5, and ≥15 years postoperatively. The primary outcome was the American Shoulder and Elbow Surgeons (ASES) score. Secondary outcomes included Single Assessment Numeric Evaluation (SANE), Shoulder Activity Scale (SAS), visual analog scale, and Patient-Reported Outcomes Measurement Information System (PROMIS)-Upper Extremity (UE) scores. Patient demographic characteristics, revision surgical procedures, and complications were recorded. Generalized estimating equations were used to model scores over time, and multiple comparisons between time points were performed using Tukey adjustment., Results: This study included 60 patients with a mean follow-up period of 16.5 years (range, 15.8-17.7 years). The mean ASES score improved from 60.2 ± 18.8 preoperatively to 93.0 ± 9.4 at ≥15 years (P < .0001). The mean visual analog scale pain score decreased from 4.1 ± 0.7 preoperatively to 0.7 ± 0.3 at ≥15 years (P < .0001). The average SANE, SAS, and PROMIS-UE scores at ≥15 years were 87.8 ± 14.8, 8.8 ± 4.3, and 49.6 ± 10.2, respectively. Of 60 patients, 7 underwent revision surgery. Older age and female sex were associated with lower SAS scores at 15 years, whereas female sex was associated with lower PROMIS-UE scores. There were no factors predictive of ASES or SANE scores., Conclusion: At long-term follow-up (≥15 years), the patient-reported outcomes of all-arthroscopic rotator cuff repair show significant improvement from baseline preoperative function and remain durable over a period of 15 years. This information is useful in counseling patients regarding the long-term results of this procedure., (Copyright © 2022. Published by Elsevier Inc.)

Background: The role of the long head of the biceps tendon (LHBT) in glenohumeral stability is not fully understood. Most objects are lifted in the sagittal plane with forward flexion, which stresses the posterior aspect of the unconstrained glenohumeral joint. Determining the mechanism by which the shoulder maintains stability with functional motions is important to understanding the pathoanatomy of degenerative shoulders. Our hypothesis was that the LHBT resists posterior translation of the humeral head (HH) during forward flexion by tensioning the posterior capsuloligamentous complex., Methods: Ten fresh-frozen cadaveric shoulders were tested using an established shoulder simulator that loads the LHBT, rotator cuff, and deltoid tendons through a system of pulleys. A motion tracking system recorded glenohumeral translations with an accuracy of ±0.2 mm. In each subject, the scapula was fixed and the humerus was tested in 6 positions: 30° and 60° of glenohumeral forward flexion at (1) maximum internal rotation (IR), (2) neutral rotation, and (3) maximum external rotation (ER). The deltoid was loaded with 100 N, and the infraspinatus and subscapularis were loaded with 22 N each. The difference in glenohumeral translation was calculated at each position comparing the LHBT loaded with 45 N or unloaded., Results: At 30° of glenohumeral forward flexion, unloading the LHBT increased HH posterior translation by 2.5 mm (±0.9 mm; P < .001), 1.7 mm (±1.0 mm; P < .001), and 1.0 mm (±0.9 mm; P = .01) at maximum ER, neutral rotation, and maximum IR, respectively. At 60° of glenohumeral forward flexion, unloading the LHBT increased HH posterior translation by 2.8 mm (±1.2 mm; P < .001), 2.4 mm (±1.6 mm; P < .001), and 1.7 mm (±1.4 mm; P < .001) at maximum ER, neutral rotation, and maximum IR, respectively., Conclusion: LHBT loading resists posterior translation of the HH during forward flexion. These data support the role of the LHBT as a posterior stabilizer of the shoulder, specifically when a person is carrying objects in front of them. Further work is needed to determine if unloading the LHBT, as is done with biceps tenotomy or tenodesis, may eventually lead to posterior labral pathology, or to the posterior glenoid wear commonly seen with osteoarthritis., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Reverse total shoulder arthroplasty is often performed to treat rotator cuff tear arthropathy with irreparable rotator cuff tears. Patients with full-thickness tears involving the posterior cuff and teres minor specifically lose active external rotation of the humerus, limiting activities of daily living. A latissimus dorsi transfer has been described as one potential solution, but few studies have compared different latissimus dorsi transfer sites. This study assesses the biomechanics of 3 latissimus dorsi transfer sites, examining external rotation, deltoid muscle forces, and force across the glenoid for specific activities., Methods: The Newcastle Shoulder Model was modified to include a Delta III reverse shoulder arthroplasty and was used to model the effects of 3 latissimus dorsi transfer sites-anterior, posterolateral, and posterodistal-in the setting of teres minor deficiency. The latissimus dorsi was represented by 5 muscle elements approximating anatomic fascicle divisions. Kinematic data sets representing common activities were input into the model, allowing calculation of muscle forces and glenoid loads., Results: Each of the 3 latissimus dorsi transfer sites demonstrated a change of moment arm from internal to external rotation with increased magnitude. Average maximum deltoid muscle forces and glenoid loading across all motions decreased for each of the 3 transfer sites, with the greatest decreased force noted for the posterior deltoid. This decrease in deltoid force and glenoid loading was significantly greater with the anterior and posterolateral transfer sites, relative to the posterodistal site., Discussion: Latissimus dorsi transfer to all 3 sites in the setting of reverse total shoulder arthroplasty and posterior rotator cuff deficiency resulted in large external rotation moment arms. The transferred latissimus dorsi shared the external rotation load and resulted in decreased deltoid forces and glenoid loading with very small differences between the 3 transfer sites. The posterodistal location reduced deltoid force and glenoid loading to a lower degree compared with other sites, but it also showed that it did not alter the tendon length compared with the native shoulder., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Aseptic loosening from implant-associated osteolysis in reverse shoulder arthroplasty (RSA) may contribute to premature implant failure. Although articular side polyethylene (PE) damage has been well documented in the literature, no studies to date have investigated backside wear in RSA. The aims of this investigation were to (1) document and compare the damage between the backside and articular surface in explanted RSA components, (2) assess whether certain quadrants have a greater propensity for damage, and (3) report the most common mode(s) of backside PE damage., Methods: Twenty-one RSA humeral liners retrieved during revision procedures between 2005 and 2014 were included for analysis. The mean time between implantation and extraction was 16 months (10 days-88 months). Diagnoses at the time of revision included dislocation (10), infection (4), mechanical failure (3), loosening (2), and unknown (2). Liners were examined under light microscopy (×10-30 magnification) and damage on the articular and backside of the liner surface was graded using the modified Hood score. The location and damage modality were compared between the articular side and backside of the implant., Results: Damage was noted on the articular surfaces of all 21 liners and on the backside surface of 20 liners. The total damage in all the quadrants was higher on the articular surface than on the backside of the component, with a mean difference in total quadrant damage scores of 11.74 ± 3.53 (P < .001). There was no difference in damage among the quadrants on the backside (P = .44) or the articular surface (P = .08). The articular side exhibited greater scratching, abrasion, and surface deformation than the backside (P < .001)., Conclusions: This short-term retrieval study demonstrated that backside PE damage occurs on the humeral component of RSA implants. There was greater damage to the articular side of the liner but wear to the backside was present in almost all liners. The clinical importance of backside wear in RSA and its overall contribution to PE particulate disease and osteolysis needs further investigation., (Copyright © 2021. Published by Elsevier Inc.)

Background: Irreparable subscapularis (SSc) tears alter the dynamic force coupling of the shoulder, resulting in pain, weakness, and impaired shoulder function. Pectoralis major (Pma), pectoralis minor (Pmi), and latissimus dorsi (LD) transfers are treatment options for irreparable SSc tears, but clinical outcomes vary. The purpose of this study was to compare the biomechanical properties of Pma, Pmi, and LD transfers in an SSc-deficient shoulder using a computational model., Methods: A computer shoulder model was used to investigate the moment arms of Pma, Pmi, and LD tendon transfers compared with an intact SSc. Nine computed tomography scans from subjects without osteoarthritis were used. Virtual Pma, Pmi, and LD transfers were performed to the upper border of the SSc insertion site on the lesser tuberosity of the humerus. Muscle moment arms were computed for functional motions of 0°-80° of internal rotation with the arm in 20° and 90° of shoulder abduction and 0°-150° of shoulder abduction. The results were compared with those of the native SSc moment arms. A repeated-measures analysis of variance was then performed to determine significant differences., Results: Internal rotation moment arms of the transferred Pma and Pmi decreased significantly after 30° and 40° of internal rotation compared with the SSc moment arm of the intact shoulder, whereas the moment arm of LD transfer more closely mimicked that of the native SSc through 0°-80° of internal rotation. All 3 tendon transfer configurations demonstrated weak abductive moment arms (7.6-8.0 mm), comparable to the intact SSc (7.8 mm) but significantly lower than the intact adductive moment arms of the native Pma and LD (26.8 mm and 28.2 mm, respectively)., Conclusion: LD transfer most closely approximates the native SS regarding internal rotation moment arms. However, LD transfer also showed a reduction in adductive moment arms., (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 determine whether postoperative patient-reported outcomes improved over time following anatomic total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RTSA)., Methods: We performed a retrospective analysis of prospectively collected patient-reported outcomes from our institution's registry between 2008 and 2018 (N = 1899). American Shoulder and Elbow Surgeons (ASES) scores at a minimum of 2 years postoperatively were required. Univariable linear models were used to test the association between year of surgery and improvement in ASES scores at 2- and 5-year follow-up, as well as any association with age, sex, primary or revision surgery, hand dominance, American Society of Anesthesiologists classification, rotator cuff status, primary diagnosis, and Walch classification. Multivariable models were created to analyze ASES score improvement by index year while controlling for significant factors., Results: In the univariable analysis, 5-year ASES difference scores increased each year by a mean of 1.65 (P < .001; 95% confidence interval [CI], 0.75-2.55) for TSA, 2.50 (P = .014; 95% CI, 0.52-4.49) for RTSA, and 1.64 (P < .001; 95% CI, 0.81-2.47) for the overall population. Patient sex, American Society of Anesthesiologists classification, rotator cuff status, primary diagnosis, Walch classification, and revision procedures were also significant factors affecting ASES scores. On multivariable analysis controlling for these factors, 5-year ASES difference scores were still significantly associated with year of surgery, increasing each year by a mean of 2.20 (P < .001; 95% CI, 0.91-3.50) for TSA, 4.83 (P < .001; 95% CI, 1.17-8.49) for RTSA, and 1.66 (P < .001; 95% CI, 0.81-2.51) for the entire population., Conclusion: Both anatomic TSA and RTSA patients reported increasing ASES difference scores at 5-year follow-up as time passed. These findings may indicate that advances in shoulder arthroplasty have resulted in better patient outcomes over time. Further research is needed to clarify which factors influence improvements in outcomes, particularly for revision procedures., (Copyright © 2021. Published by Elsevier Inc.)

Background: Success of superior capsule reconstruction (SCR) using both fascia lata (FL) and human acellular dermal (ACD) allografts have been reported. One possible explanation for a discrepancy in outcomes may be attributed to graft thickness. SCR with commercially available 3-mm-thick ACD allograft is not biomechanically equivalent to FL. Our hypothesis was that SCR with a single 6-mm-thick ACD allograft will restore the subacromial space distance (SubDist) and peak subacromial contact pressures (PSCPs) to intact shoulder and will be comparable to SCR with an 8-mm FL allograft., Methods: Eight cadaveric shoulders were tested in 4 conditions: intact, irreparable supraspinatus tear (SST), SCR FL allograft (8-mm-thick), and SCR single ACD allograft (6-mm-thick). SubDist and PSCP were measured at 0°, 30°, and 60° of glenohumeral abduction in the scapular plane. Parameters were compared using a repeated measures analysis of variance with Tukey post hoc test, and graft dimensions were compared using a Student t test., Results: SST had decreased SubDist (P < .05) and increased PSCP (P < .05) compared with the intact state. At all angles, the SCR ACD allograft demonstrated increased SubDist compared with the tear condition (P < .001), with no difference between grafts. Furthermore, there was decreased PSCP after both ACD and FL SCR compared with the intact condition, with no difference between grafts at 0° (P = .006, P = .028) and 60° abduction (P = .026, P = .013). Both ACD and FL grafts elongated during testing., Conclusions: Our results suggest SCR with a single 6-mm-thick ACD allograft is noninferior to FL regarding SubDist and PSCP while completely restoring the superior stability of the glenohumeral joint compared with the intact state., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Patients frequently undergo interventions before shoulder arthroplasty, including injections and arthroscopy. Although the potential impact of injections on postoperative outcomes such as infection has been well studied, it is less clear whether prior arthroscopy has an impact on infection rates after shoulder arthroplasty. The purpose of this study was to determine whether prior ipsilateral shoulder arthroscopy is associated with an increased risk of postoperative infection after shoulder arthroplasty., Methods: Patients who underwent shoulder arthroplasty, including hemiarthroplasty, total shoulder arthroplasty, or reverse shoulder arthroplasty with a minimum of 1-year preoperative database exposure, were queried using Current Procedural Terminology codes from 2 large insurance databases, including both private-payer (Humana, 2008-2017) and Medicare (2006-2014) data. Patients with procedures for infection, fractures, or without laterality data were excluded. Those who underwent ipsilateral shoulder arthroscopy within 2 years before their arthroplasty were identified and compared with controls who did not undergo prior arthroscopy. Each database was analyzed separately. Periprosthetic infection within 1 year after arthroplasty was queried for each group and compared using a logistic regression analysis with control for demographic and comorbidity confounders., Results: A total of 9362 Medicare patients and 17,716 private-payer patients were included in the study. Of these, 486 (5.2%) Medicare patients and 685 (3.9%) private-payer patients underwent prior arthroscopy. In the Medicare database, prior arthroscopy was also associated with a postarthroplasty infection rate of 3.9% as compared with 1.9% in the control group (odds ratio: 1.96, 95% confidence interval: 1.20-3.22, P = .003). Similarly, in the private insurance cohort, prior shoulder arthroscopy was associated with a postarthroplasty infection rate of 2.9% as compared with 1.4% in the control group (odds ratio: 1.85, 95% confidence interval: 1.13-3.03, P = .005)., Conclusion: Shoulder arthroscopy performed within 2 years before shoulder arthroplasty is associated with a higher infection rate in the first year after shoulder arthroplasty., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The purpose was to analyze the influence of deltoid lengthening due to different implant designs and anatomic variations of the acromion and scapular spine (SS) in the parasagittal plane on strain patterns after reverse shoulder arthroplasty (RSA)., Methods: Ten cadaveric shoulders with strain rosettes placed on the surface of the acromial body (Levy II) and SS (Levy III) were tested using a shoulder simulator. RSA using humeral onlay (+3, +5, +8, +10, +13 mm) and glenosphere lateralization (0, +6 mm) was performed. Arm lengthening and magnitude of strain on acromion/SS were measured. The length of deltoid was assessed using validated computer modeling. Anatomic variance of the SS angle and position of acromion in relation to the scapular plane was examined. For comparison of strain as a function of deltoid lengthening, 25 mm was used as a threshold value for comparison based on previous literature demonstrating a decrease in Constant score and active anterior elevation in patients with arm lengthening >25 mm., Results: At maximal deltoid lengthening (30.8 mm), average strains were 1112 με (acromion) and 1165 με (SS) (P < .01). There was an 82.6% increase in acromial strain at maximum lengthening compared with 25 mm (P = .02) and a strain increase of 79 με/mm deltoid lengthening above a threshold of 25 mm. The strain results delineated 2 anatomic groups: 5 of 10 specimens (group A) showed higher strain on SS (1445 με) vs. acromion (862 με, P = .02). Group A had a more posteriorly oriented acromion, whereas group B was anteriorly oriented (P < .001)., Conclusion: Deltoid lengthening above 25 mm produced large strains on the acromion/SS. Anatomic variation may indicate that as the acromion is more posteriorly oriented, the SS takes more strain from the deltoid vs. the acromion. Our study's data may help surgeons identify a high-risk population for increased strain patterns after RSA., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Hypothesis/purpose: The objective is to develop and validate an artificial intelligence model, specifically an artificial neural network (ANN), to predict length of stay (LOS), discharge disposition, and inpatient charges for primary anatomic total (aTSA), reverse total (rTSA), and hemi- (HSA) shoulder arthroplasty to establish internal validity in predicting patient-specific value metrics., Methods: Using data from the National Inpatient Sample between 2003 and 2014, 4 different ANN models to predict LOS, discharge disposition, and inpatient costs using 39 preoperative variables were developed based on diagnosis and arthroplasty type: primary chronic/degenerative aTSA, primary chronic/degenerative rTSA, primary traumatic/acute rTSA, and primary acute/traumatic HSA. Models were also combined into diagnosis type only. Outcome metrics included accuracy and area under the curve (AUC) for a receiver operating characteristic curve., Results: A total of 111,147 patients undergoing primary shoulder replacement were included. The machine learning algorithm predicting the overall chronic/degenerative conditions model (aTSA, rTSA) achieved accuracies of 76.5%, 91.8%, and 73.1% for total cost, LOS, and disposition, respectively; AUCs were 0.75, 0.89, and 0.77 for total cost, LOS, and disposition, respectively. The overall acute/traumatic conditions model (rTSA, HSA) had accuracies of 70.3%, 79.1%, and 72.0% and AUCs of 0.72, 0.78, and 0.79 for total cost, LOS, and discharge disposition, respectively., Conclusion: Our ANN demonstrated fair to good accuracy and reliability for predicting inpatient cost, LOS, and discharge disposition in shoulder arthroplasty for both chronic/degenerative and acute/traumatic conditions. Machine learning has the potential to preoperatively predict costs, LOS, and disposition using patient-specific data for expectation management between health care providers, patients, and payers., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Instability arthropathy is a known cause of glenohumeral osteoarthritis (OA) among patients with and without prior shoulder stabilization. This study aims to compare the clinical, radiographic, and patient-reported outcome measure (PROM) scores among total shoulder arthroplasty (TSA) patients with and without a history of shoulder stabilization., Methods: A case-control study was performed comparing 20 patients with a history of anterior shoulder stabilization (11 open, 9 arthroscopic) who underwent TSA to a matched cohort of 20 TSA patients without a history of shoulder surgery (mean follow-up = 2.8 years). Patients were matched by sex, age, and baseline American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score within 10 points (mean age 59.6 ± 9.6 years). Patient characteristics, operative findings, and preoperative and postoperative radiographic characteristics for both groups were reported. Comparisons were made regarding PROM scores (ASES, 12-Item Short Form Health Survey (SF-12), Shoulder Activity Scale [SAS], numeric rating scale for pain) at baseline, 2 years, and 5 years and patient satisfaction at 2 years., Results: Intraoperative findings of subscapularis scarring or attenuation was common among patients with prior anterior stabilization. The instability cohort did have a higher percentage of B2/B3 glenoid types than the OA cohort (45% vs. 15%), but this was not significantly different possibly because of the small sample size. At 2 years, both instability and OA groups reported significant improvement in pain, function, and activity level. There was no difference between groups on any PROMs or patient satisfaction level. At 5 years, instability patients had significantly lower scores on the ASES and the SF-12 PCS than the OA group., Conclusion: There was notable alterations in both soft tissue and bony morphology among patients with prior anterior stabilization. After TSA, both instability and primary OA groups showed significant improvements at 2 years. However, PROMs for instability patients deteriorated at 5 years compared with the control group. Complex bony and soft tissue imbalances may contribute to more unpredictable long-term PROM scores. Thoughtful preoperative consideration of these factors should influence decision making regarding selection of TSA for management of OA in this complex patient cohort., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Although anatomic total shoulder arthroplasty (TSA) successfully improves pain and function, not all patients improve clinically. This study was conducted to determine patient-related factors for failure to achieve improvement after primary TSA for osteoarthritis at 2 years postoperatively., Methods: This prospective study reviewed an institutional shoulder registry for consecutive patients who underwent primary TSA for osteoarthritis from 2007 to 2013 with baseline and 2-year postoperative American Shoulder and Elbow Surgeons (ASES) Standardized Shoulder Assessment Form scores. A failed outcome was defined as (1) a failure to reach the ASES minimal clinically important difference of 16.1 points or (2) revision surgery within 2 years of the index procedure, or both. Univariate and multivariable analyses of clinical and demographic patient factors were performed using logistic regression., Results: Of 459 arthroplasties that met inclusion criteria, 411 were deemed successful by the aforementioned criteria, and 48 (10.5%) failed to achieve a desirable outcome. Clinical risk factors associated with failure included previous surgery to the shoulder (P = .047), presence of a torn rotator cuff (P = .025), and presence of diabetes (P = .036), after adjusting for age, sex, race, and body mass index. A higher preoperative ASES score at baseline was associated with failure (P < .001)., Conclusion: Previous shoulder surgery, a rotator cuff tear requiring repair during TSA, presence of diabetes, surgery on the nondominant arm, and a higher baseline ASES score were associated with a higher risk of failing to achieve improvement after anatomic TSA., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The bicipital tunnel is the extra-articular, fibro-osseous structure that encloses the long head of the biceps tendon., Methods: Twelve cadaveric shoulder specimens underwent in situ casting of the bicipital tunnel with methyl methacrylate cement to demonstrate structural competence (n = 6) and en bloc harvest with gross and histologic evaluation (n = 6). The percentage of empty tunnel was calculated histologically by subtracting the proportion of cross-sectional area of the long head of the biceps tendon from that of the bicipital tunnel for each zone., Results: Cement casting demonstrated that the bicipital tunnel was a closed space. Zone 1 extended from the articular margin to the distal margin of the subscapularis tendon. Zone 2 extended from the distal margin of the subscapularis tendon to the proximal margin of the pectoralis major tendon. Zone 3 was the subpectoral region. Zones 1 and 2 were both enclosed by a dense connective tissue sheath and demonstrated the presence of synovium. Zone 3 had significantly greater percentage of empty tunnel than zones 1 and 2 did (P < .01)., Conclusion: The bicipital tunnel is a closed space with 3 distinct zones. Zones 1 and 2 have similar features, including the presence of synovium, but differ from zone 3. A significant bottleneck occurs between zone 2 and zone 3, most likely at the proximal margin of the pectoralis major tendon. The bicipital tunnel is a closed space where space-occupying lesions may produce a bicipital tunnel syndrome. Careful consideration should be given to surgical techniques that decompress both zones 1 and 2 of the bicipital tunnel., (Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Surgical management of shoulder pathologies has evolved tremendously during the past 3 decades, such that many lesions previously treated with open techniques are now addressed arthroscopically. Despite this movement, many surgeons and outcome studies continue to prefer open repairs as the gold standard, criticizing--with good reason--the reliability, reproducibility, and extended operative time of arthroscopic repairs, particularly with respect to anterior stabilizations and subscapularis repairs. With this in mind, we present the arthroscopic "subdeltoid approach," a novel standardized exposure technique for extracompartmental anterior shoulder arthroscopy. We define the subdeltoid space as the fascial plane bound superiorly by the acromion and coracoacromial ligament, medially by the coracoid and the conjoint tendon, inferiorly by the musculotendinous insertion of the pectoralis major to the humerus, and laterally by the lateral border of the humerus. When coupled with existing arthroscopic tools, this space dramatically enhances our ability to apply open techniques to some of the more challenging anterior shoulder pathoanatomy and expand the indications and efficacy of arthroscopy. This exposure technique has been used in more than 300 cases during the past decade to treat a myriad of shoulder pathologies, without any longstanding postoperative complications., (Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)