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Background: The purpose of this study was to determine whether the addition of hydrogen peroxide to the preoperative skin preparation for primary total shoulder arthroplasty is associated with a difference in patient-reported outcomes, risk for postoperative infection, and risk for revision surgery at a minimum of 2-year follow-up., Methods: This was a prospective, blinded, and controlled trial, which included a consecutive series of patients undergoing primary shoulder arthroplasty. The control group underwent standard sterile skin preparation using ethyl alcohol and ChloraPrep applicators, and the peroxide group had the same preparation with the addition of hydrogen peroxide between the alcohol and ChloraPrep applications. We then compared patient-reported outcome scores (American Shoulder and Elbow Surgeons Shoulder Score [ASES], simple shoulder test [SST], visual analog scale [VAS]), infections, and revision surgeries between the two groups at 2-year follow-up., Results: Of the 61 patients included in the original study, 52 of 58 (85%) living patients agreed to participate in this study. No preoperative differences were observed between groups. No difference was observed in ASES, SST, or VAS scores at 2 years. More revision surgeries were done in the control group (7 versus 2, P = 0.268) and Cutibacterium acnes infections (2 versus 0, P = 0.168)., Conclusion: The addition of hydrogen peroxide to the preoperative skin preparation before primary shoulder arthroplasty is safe, and additional research is warranted to investigate whether it may decrease the risk for revision surgery and postoperative C acnes infection., Level of Evidence: III., (Copyright © 2024 by the American Academy of Orthopaedic Surgeons.)

Background: Over-prescription of opioids in the United States increases risks of opioid dependence, overdose, and death. Increased perioperative and postoperative opioid use during orthopedic shoulder surgery is a significant risk factor for long term opioid dependence. The authors hypothesized that a multidisciplinary perioperative pain management program (Transitional Pain Service or TPS) for major shoulder surgery would lead to a reduced amount of opioids required postoperatively., Methods: A TPS was implemented at a Veterans Affairs Medical Center focused on non-opioid pain management and cessation support. Opioid consumption during the implementation of the TPS was compared to a historical cohort. All patients undergoing shoulder arthroplasty or rotator cuff repair were included. The primary outcome was the proportion of patients continuing opioid use at 90 days postoperatively. Secondary outcomes included postoperative pain scores, time to opioid cessation, and median opioid tablets consumed at 90-days. A multivariable model was developed to predict total opioid use at 90-days postoperatively. Kaplan Meier curves were calculated for time to opioid cessation., Results: The TPS group demonstrated decreased persistent opioid use at 90 days post-discharge (12.6% vs. 28.6%; p=0.018). Independent predictors associated with increased total opioid tablet prescriptions at 90 days included length of stay (β=19.17), anxiety diagnosis (β=37.627), and number of tablets prescribed at discharge (β=1.353). Shoulder arthroplasty surgery (TSA) was associated with decreased 90-day opioid utilization (β= -32.535) when compared to cuff repair (RCR). Median time to cessation was shorter in TSA (6 days) when compared with RCR (8 days). Pain scores were reduced compared to population mean by post-discharge day 2 for TSA and by post-discharge day 7 for RCR. Median number of post-discharge opioid tablets (oxycodone 5 mg) consumed under TPS management was 25 in both RCR and TSA surgery groups (180 MME)., Discussion and Conclusions: This study demonstrates that a TPS reduces the amount of opioid use of patients undergoing shoulder arthroplasty or cuff repair at 90 days when compared with a historical control. Multivariable regression indicated that fewer opioid tablets at discharge was a modifiable factor that may aid in reducing opioid consumption and that anxiety diagnosis, increased length of stay, and cuff repair surgery were other factors independently associated with increased opioid consumption. This data will assist surgeons in counseling patients, setting narcotic use expectations, and minimizing overprescribing. Use of a similar multidisciplinary perioperative pain management program may greatly reduce opioid over prescriptions nationally., (Copyright © 2024. Published by Elsevier Inc.)

Background: One method to augment rotator cuff repair is to pass dermal allograft pledgets along the sutures that bridge from the medial to the lateral row. It remains unclear whether this augmentation method alters repair biomechanics., Methods: This was a controlled laboratory study. After an a priori power analysis, 9 pairs of rotator cuffs underwent double-row suture bridge rotator cuff repair, half randomized to augmentation with dermal allograft pledgets passed along the suture bridge sutures. Repairs were then mounted on a material testing system and loaded cyclically 500 cycles to measure applied force and displacement. Repairs then underwent ultimate failure testing, and stiffness, ultimate failure force, and ultimate failure displacement were measured. Paired t tests were performed to compare between groups., Results: There were no differences between groups in construct gapping with cyclic loading after 500 cycles (P = .885). There were no differences between the augmented and control groups in yield force (103.5 ± 5.0 vs. 101.4 ± 5.9 N, respectively, P = .183), stiffness (94.2 ± 13.9 vs. 90.9 ± 13.8, P = .585), or ultimate failure force (255.3 ± 65.8 vs. 285.3 ± 83.2, P = .315). There were no differences between groups in failure modes, with most specimens failing by cuff tissue tearing within or medial to the construct., Conclusion: The addition of dermal allograft pledgets does not positively or negatively influence the time-zero biomechanical characteristics of double-row suture bridge rotator cuff repair., (Copyright © 2024. Published by Elsevier Inc.)

Background: Both inlay and onlay humeral implants are available for reverse total shoulder arthroplasty (rTSA), but biomechanical data comparing these components remain limited. This study investigated the effects of inlay and onlay rTSA humeral components on shoulder biomechanics using a biorobotic shoulder simulator., Methods: Twenty fresh-frozen cadaveric shoulders were tested before and after rTSA with either an inlay or onlay humeral implant. Comparisons were performed between the most commonly implanted configurations for each implant (baseline) and with a modification to provide equivalent neck-shaft angles (NSAs) for the inlay and onlay configurations. Specimens underwent passive range-of-motion (ROM) assessment with the scapula held static, and scapular-plane abduction was performed, driven by previously collected human-subject scapulothoracic and glenohumeral kinematics. Passive ROM glenohumeral joint angles were compared using t tests, whereas muscle force and excursion data during scapular-plane elevation were evaluated with statistical parametric mapping and t tests., Results: Maximum passive elevation was reduced for the inlay vs. onlay humeral components, although both implants caused reduced passive elevation vs. the native joint. Inlay rTSA also demonstrated reduced passive internal rotation at rest and increased external rotation at 90° of humerothoracic elevation vs. the native joint. All preoperative planning estimates of ROM differed from experiments. Rotator cuff forces were elevated with an onlay vs. inlay humeral implant, but simulated muscle excursions did not differ between systems. Compared with the native joint, rotator cuff forces were increased for both inlay and onlay implants and deltoid forces were reduced for inlay implants. Muscle excursions were dramatically altered by rTSA vs. the native joint. Comparisons of inlay and onlay humeral implants with equivalent NSAs were consistent with the baseline comparisons., Conclusions: Rotator cuff forces required to perform scapular-plane abduction increase following rTSA using both inlay and onlay implants. Rotator cuff forces are lower with inlay implants compared with onlay implants, although inlay implants also result in reduced passive-elevation ROM. Deltoid forces are lower with inlay implants in comparison to the native joint but not with onlay implants. The differences between inlay and onlay components are largely unaffected by NSA, indicating that these differences are inherent to the inlay and onlay designs. In those patients with an intact rotator cuff, decreased rotator cuff forces to perform abduction with an inlay humeral implant compared with an onlay implant may promote improved long-term outcomes owing to reduced deltoid muscle fatigue when using an inlay implant., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Preoperative planning is an integral aspect of managing complex deformity in reverse shoulder arthroplasty (RSA). The purpose of this study was to compare the success of patient specific instrumentation (PSI) and 3D computer-assisted planning with standard instrumentation (Non-PSI) in achieving planned corrections of the glenoid among patients undergoing RSA with severe bony deformity requiring glenoid bone grafts., Methods: A retrospective case-control study was performed, including all patients that underwent RSA with combined bone grafting procedures (BIO-RSA or structural bone grafting) for severe glenoid deformity by a single between June 2016 and July 2023. Patients were required to have preoperative and postoperative CT scans as well as preoperative 3D planning performed for inclusion. Patients were divided into two groups based on the use of 3D computer-assisted planning with or without PSI (PSI vs. Non-PSI). The corrected inclination and version were measured by two separate reviewers on preoperative and postoperative 2D CT scans and compared to their corresponding preoperative planning goals utilizing bivariate analyses., Results: We identified 45 patients that met our inclusion criteria (22 PSI and 23 Non-PSI). Preoperative inclination (mean ± SD) (PSI 10.12° ± 15.86°, Non-PSI 9.43° ± 10.64°; P = 0.864) and version (PSI -18.78° ± 18.3°, Non-PSI -17.82° ± 11.49°; P = 0.835) measurements were similar between groups. No significant differences in the mean deviation (error) between the postoperative and planned inclination (PSI 5.49° ± 3.72; Non-PSI 6.91° ± 5.05; P = 0.437) and version (PSI 8.37° ± 5.7; Non-PSI 5.37° ± 4.43; P = 0.054) were found between groups. No difference in the rate of outliers (>10° error) was noted in inclination (P = 0.135) or version (P = 0.445) between groups. Greater planned version correction was correlated with greater error when PSI was utilized (PSI r = 0.519, P = 0.013; Non-PSI r = 0.362, P = 0.089)., Conclusion: Both PSI and 3D computer-assisted planning without PSI (Non-PSI) appear to be useful techniques to achieve version and inclination correction among patients undergoing RSA with severe glenoid deformity required glenoid bone grafting with no clear superiority of one method over the other. Surgeons should be aware that when utilizing PSI, slightly greater error in achieving version goals may occur as version correction is increased., (Copyright © 2024. Published by Elsevier Inc.)

Background: The purpose of this study was to evaluate the relationship between multiple radiographic measures of lateralization and distalization and clinical outcome scores after a reverse total shoulder arthroplasty (RTSA)., Methods: We retrospectively evaluated all RTSAs performed by the senior author between January 1, 2007, and November 1, 2017. We then evaluated the visual analog scale for pain (VAS pain), Simple Shoulder Test (SST), and American Shoulder and Elbow Surgeons (ASES) scores and complication and reoperation rates at a minimum of 2-year follow-up. We measured preoperative and postoperative (2-week) radiographs for the lateralization shoulder angle (LSA), the distalization shoulder angle (DSA), lateral humeral offset, and the distance from the glenoid to the lateral aspect of the greater tuberosity. A multivariable analysis was performed to evaluate the effect of the postoperative radiographic measurements on final patient-reported outcomes (ASES scores, SST, and VAS pain)., Results: The cohort included 216 shoulders from unique patients who had patient-reported outcome scores available at a minimum of 2-year follow-up (average, 4.0 ± 1.9 years) for a total follow-up rate of 70%. In the multivariable models, more lateralization (LSA) was associated with worse final ASES scores -0.52 (95% confidence interval [CI]: -0.88, -0.17; P = .004), and more distalization (DSA) was associated with better final ASES scores 0.40 (95% CI: 0.11, 0.69; P = .007). More lateralization (LSA) was associated with worse final SST scores -0.06 (95% CI: -0.11, -0.003; P = .039). Finally, greater distalization (DSA) was associated with lower final VAS pain scores, ratio = 0.98 (95% CI: 0.96, 1.00; P = .021)., Conclusions: Greater distalization and less lateralization are associated with better function and less pain after a Grammont-style RTSA. When using a Grammont-style implant, remaining consistent with Grammont's principles of implant placement will afford better final clinical outcomes., (Copyright © 2024 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 preoperative planning software (PPS) accurately predicts clinical range of motion (ROM) in patients with reverse total shoulder arthroplasty 1 year postoperatively with preoperative and postoperative computed tomography (CT) scans., Methods: This was a retrospective study of 16 reverse total shoulder arthroplasty patients with preoperative and postoperative (CT) scans obtained at least 1 year postoperatively. Clinical ROM was measured in abduction, external rotation at resting abduction, extension, and flexion at a minimum of 1 year postoperatively. All clinical measurements were obtained before generation of PPS ROM values. Using postoperative CT scans, the achieved implant component positions were quantified and then replicated in PPS on the preoperative CT scans. The preoperative predicted ROM was then recorded, both with and without osteophyte removal. Bland-Altman plots were generated within each motion comparing the differences between clinically measured motion and software-predicted motion., Results: The variation in clinically measured ROM in abduction, external rotation at resting abduction, extension, and flexion were 118 ± 27 (65° to 180°), 33 ± 16 (10° to 75°), 56 ± 8 (50° to 65°), and 137 ± 25 (80° to 160°), respectively. Clinically measured motion differed greatly from PPS-predicted ROM, with mean differences of 33 ± 29 (-32 to 93) for abduction, 44 ± 25 (-38 to 57) for external rotation, 44 ± 25 (-35 to 65) for extension, and 54 ± 50 (-51 to 147) for flexion with no significant correlations between clinically measured and PPS-predicted ROM ( P > 0.05). With humeral or humeral and glenoid osteophyte resection, correlations for only flexion became significant ( P = 0.002 for both)., Conclusion: The passive glenohumeral impingement-free ROM generated from PPS incompletely predicts clinically measured active humerothoracic ROM, possibly because of the unmeasured factors of soft-tissue tension, muscular strength, humeral torsion, resting scapular posture, and, most importantly, scapulothoracic motion., Level of Evidence: IV., (Copyright © 2023 by the American Academy of Orthopaedic Surgeons.)

Background: Common genetic variants with small effect sizes have been associated with rotator cuff tearing although very few rare, highly penetrant variants have been identified. The purpose of this pilot study was to identify dominant coding variants that segregated with affected individuals in pedigrees at high risk for rotator cuff tears (RCTs). We hypothesize that rare variants contribute to symptomatic RCTs and that they can be identified in related cases with a full-thickness tear requiring surgical management., Methods: We used the Utah Population Database to identify pedigrees that exhibited a significant excess of individuals who had undergone surgical repair of a full-thickness RCT. We analyzed whole exome sequence analysis to identify rare coding variants in 9 independent affected cousin pairs (first or second cousins) who had undergone arthroscopic surgery for repair of a full-thickness RCT (mean age at diagnosis 68 years). Validation of association of the candidate variants with risk for rotator cuff tearing was accomplished utilizing data from the UK Biobank and a separate cohort of unrelated cases of full-thickness RCTs., Results: A total of 82 rare (minor allele frequency <0.005) coding variants were identified as shared in at least one cousin pair affected with full-thickness rotator cuff tearing belonging to a high-risk pedigree, which included variants in RUNX1, ADAM12 , TGFBR2 , APBB1 , PDLIM7, LTBP1 , MAP3K4, and MAP3K1 . Analysis of 39 of these variants with data available in the UK Biobank (3899 cases with rotator cuff injury and 11,697 matched controls; mean case age 59.9 years) identified a significant association with the APBB1 gene (OR = 2.37, P  = .007, uncorrected). The PDLIM7 allele was found to be in significant excess in RCT cases in a separate cohort of Utah patients with full-thickness RCTs (10 carriers out of 458 independent, unrelated patients; minor allele frequency of 0.022) compared to a minor allele frequency of 0.0058 for the European (non-Finnish) control population rate (749 carriers out of 128612 tested) (chi-square test: 19.3 [ P  < .001])., Discussion: The analysis of closely related individuals with confirmed full-thickness RCTs from high-risk pedigrees has identified 82 rare, shared candidate genetic predisposition coding variants. Association of the PDLIM7 allele with risk for tear was confirmed in an independent cohort of RCTs. Further analysis of the variant alleles is required for confirmation of these genes in rotator cuff tearing., (© 2024 The Authors.)

Failure of healing after rotator cuff repair (RCR) is common. The purpose of the current study was to evaluate the effect of systemic estrogen or testosterone supplementation on tendon healing after RCR. Seventy-two adult male mice were utilized for all experiments. The supraspinatus tendon was transected and repaired with 6-0 Prolene suture on the left shoulder of 51 animals. Mice were segregated into three groups postoperative: (1) vehicle group (VG; n = 18), (2) estrogen group (EST; n = 17), and (3) testosterone group (TST; n = 16). An unrepaired control group (unrepaired, n = 21) did not have surgery. Utilizing these animals, histological analysis, activity testing, biomechanical testing and RNA sequencing (RNA-seq) was performed. At 8 weeks post-RCR, TST, and EST supplementation improved the overall histologic structure of the repaired enthesis site. No differences in ultimate failure loads or stiffness were detected between VG, EST, and TST groups after biomechanical testing. RCR caused a reduction in wheel activity compared to unrepaired controls and supplementation with TST restored wheel activity. RNA-seq analysis indicated that estrogen and testosterone regulated different pathways associated with enthesis healing, including a suppression of inflammatory signaling. Supplementation with sex hormones improved the structure of the repaired tendon enthesis and significantly regulated expression of diverse pathways regulating multiple biological processes. Testosterone administration following RCR restored wheel activity without having a detrimental impact on biomechanical strength. Future human studies of sex hormone supplementation after RCR are warranted as supplementation in an animal model may improve tendon enthesis healing., (© 2023 Orthopaedic Research Society.)

Introduction: This study examined 2-year outcomes of patients who underwent delayed rotator cuff repair (RCR) compared with those who underwent RCR without delay., Methods: In this prospective comparative study, two groups were formed: (1) patients planning RCR during a 6-week elective surgery ban and (2) patients undergoing RCR at least 6 weeks after the ban. The Simple Shoulder Test, American Shoulder and Elbow Surgeon score, and visual analog scale for pain were collected preoperatively and at 2 years postoperatively. Magnetic resonance imaging assessed healing 6 months postoperatively., Results: With a 93.3% 2-year follow-up (13/15 delay group, 15/15 control), there was an 87-day difference in presentation to surgery (P = 0.001), with no significant preoperative demographic or tear characteristic differences between groups. Intraoperatively, there were no differences between groups in repair characteristics. Preoperative versus postoperative differences in American Shoulder and Elbow Surgeon score (P < 0.001), visual analog scale (P < 0.001), and Simple Shoulder Test scores (P < 0.001) were significant but not between groups (P = 0.650, 0.586, 0.525). On MRI, 58% in the delay group and 85% in the control group had healed (P = 0.202)., Discussion: Although a 3-month delay showed no statistically significant effect on outcomes, the delay group had an approximately 27% higher failure rate. Thus, although a 3-month period of nonsurgical treatment before RCR may be reasonable, larger studies are warranted for definitive conclusions., (Copyright © 2024 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)

Rotator cuff repair is commonly performed, and stiffness represents one of the most common complications. Unique characteristics of postoperative stiffness, including its natural history and pathoanatomy, differentiate it from other etiologies of shoulder stiffness. Patient risk factors that have been associated with postoperative stiffness should be reviewed to better help clinicians tailor their presurgical risk assessment. Although stiffness in this setting has clinical consequences for patients' postoperative shoulder function, it is important to discuss the important implications of stiffness as it relates to rotator cuff healing. Multiple strategies have been proposed to decrease the incidence of postoperative stiffness. There is evidence to support these preventive strategies, and it has led to author recommendations for treatment of refractory cases and prevention.

Purpose: To clinically evaluate a subset of patients who underwent a revision subpectoral biceps tenodesis for a clinically failed proximal biceps tenodesis., Methods: This is a retrospective case series of patients with at least 2-year follow-up who had undergone a revision biceps tenodesis after clinical failure of a proximal biceps tenodesis between January 2008 and February 2020 by a single surgeon. Patients who underwent concomitant procedures, such as revision cuff repair, were excluded. Patients with a minimum of 2 years duration status postrevision subpectoral tenodesis were contacted for informed consent and outcome data, which included Simple Shoulder Test, American Shoulder and Elbow Surgeons score, visual analog scale for pain, and subjective reporting of arm weakness and satisfaction., Results: Fourteen patients were initially identified as meeting inclusion criteria with a minimum 2-year follow-up achieved for 11 of 14 patients (78.5% follow-up). The mean follow-up time was 8.1 years (range, 2.7-14.8 years). After the primary biceps tenodesis, a mean of 8.0 ± 9.6 months passed before the revision subpectoral biceps tenodesis was performed. The average postoperative active forward elevation and adducted external rotation were 159 ± 7° and 47 ± 17°, respectively. The mean ± standard deviation (range) follow-up American Shoulder and Elbow Surgeons score was 79 ± 23 (30-100), Simple Shoulder Test was 11 ± 2 (7-12), and visual analog scale for pain was 2.6 ± 2.8 (0-9). All 11 patients reported being satisfied with their operation and would elect to have the operation again., Conclusions: Revision subpectoral biceps tenodesis is a viable procedure for addressing patients with persistent pain following initial proximal biceps tenodesis. Although some persistent pain is common, revision subpectoral biceps tenodesis demonstrates a high patient satisfaction and good functional outcomes., Level of Evidence: Level IV, therapeutic case series., (© 2023 The Authors.)

Background: Operative treatment of scapulothoracic bursitis most commonly comprises arthroscopic scapulothoracic bursectomy with or without partial superomedial angle scapuloplasty. There is currently no consensus regarding whether or when scapuloplasty should be performed. Prior studies are limited to small case series, and optimal surgical indications are not yet established. The purposes of this study were (1) to retrospectively review patient-reported outcomes of arthroscopic treatment of scapulothoracic bursitis and (2) to compare outcomes between scapulothoracic bursectomy alone and bursectomy with scapuloplasty. We hypothesized that bursectomy with scapuloplasty would provide superior pain relief and functional improvement., Materials and Methods: All cases of scapulothoracic débridement with or without scapuloplasty completed at a single academic center from 2007 through August 2020 were reviewed. Patient demographic characteristics, symptomatology data, physical examination findings, and corticosteroid injection response data were collected from the electronic medical record. Visual analog scale pain, American Shoulder and Elbow Surgeons, Simple Shoulder Test, and Single Assessment Numeric Evaluation scores were collected. Comparisons between the group undergoing bursectomy alone and the group undergoing bursectomy with scapuloplasty were made using the Student t test for continuous variables and the Fisher exact test for categorical variables., Results: Thirty patients underwent scapulothoracic bursectomy alone, and 38 patients underwent bursectomy with scapuloplasty. Final follow-up data were available for 56 of 68 cases (82%). Final postoperative visual analog scale pain scores (3.4 ± 2.2 and 2.8 ± 2.2, respectively; P = .351), American Shoulder and Elbow Surgeons scores (75.8 ± 17.7 and 76.5 ± 22.5, respectively; P = .895), and Simple Shoulder Test scores (8.8 ± 2.3 and 9.5 ± 2.8, respectively; P = .340) were similar between the bursectomy-alone and bursectomy-with-scapuloplasty groups., Conclusion: Both arthroscopic scapulothoracic bursectomy alone and bursectomy with scapuloplasty are effective treatments for scapulothoracic bursitis. Operative time is shorter without scapuloplasty. In this retrospective series, these procedures showed similar outcomes regarding shoulder function, pain, surgical complications, and rates of subsequent shoulder surgery. Further studies with a focus on 3-dimensional scapular morphology may help optimize patient selection for each of these procedures., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Prior studies have demonstrated that conservatively treated rotator cuff tears and rotator cuff tendinopathy may continue to progress. It is unclear whether that rate of progression differs between sides in patients with bilateral disease. This study evaluated the likelihood of progression of rotator cuff disease as confirmed via magnetic resonance imaging (MRI) in individuals with symptomatic bilateral pathology, treated conservatively for a minimum of 1 year., Methods: We identified patients with bilateral rotator cuff disease confirmed via MRI within the Veteran's Health Administration electronic database. A retrospective chart review via the Veteran's Affairs electronic medical record was performed. Progression was determined using 2 separate MRIs with a minimum of 1 year apart. We defined progression as (1) a progression from tendinopathy to tearing, (2) an increase from partial-thickness to full-thickness tearing, or (3) an increase in tear retraction or tear width of at least 5 mm., Results: Four hundred eighty MRI studies from 120 Veteran's Affair patients with bilateral, conservatively treated rotator cuff disease were evaluated. Overall, 42% (100/240) of rotator cuff disease had progressed. No significant difference was found between progression of right vs. left rotator cuff pathology, with right shoulder pathology progressing at a rate of 39% (47/120), while left shoulder disease progressed at a rate of 44% (53/120). The likelihood of disease progression was associated with less initial tendon retraction ( P value = .016) and older age ( P value = .025)., Conclusions: Rotator cuff tears are no more likely to progress on the right, as compared to the left side. Older age and less initial tendon retraction were found to be predictors of disease progression. These suggest that higher activity level may not associate with greater progression of rotator cuff disease. Future prospective studies evaluating progression rates between dominant vs. nondominant shoulders are warranted., (© 2023 The Author(s).)

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: One innovation to reduce glenoid loosening in total shoulder arthroplasty (TSA) is a large, central ingrowth peg. However, when bone ingrowth fails to occur, there is often increased bone loss surrounding the central peg which may increase complexity of subsequent revisions. Our goal was to compare outcomes between central ingrowth pegs and noningrowth pegged glenoid components during revision to reverse total shoulder arthroplasty., Methods: In a comparative retrospective case series, all patients who underwent TSA-to-reverse TSA revision between 2014 and 2022 were reviewed. Demographic varibles as well as clinical and radiographic outcomes were collected. Ingrowth central peg and noningrowth pegged glenoid groups were compared using t -test, Mann-Whitney U, Chi-Square, or Fisher's exact tests where indicated., Results: Overall, 49 patients were included: 27 underwent revision from noningrowth and 22 from central ingrowth components. Females more commonly had noningrowth components (74% vs. 45%, P  = .04) and preoperative external rotation was higher in central ingrowth components ( P  = .02). Time to revision was significantly earlier in central ingrowth components (2.4 vs. 7.5 years, P  = .01). Structural glenoid allografting was required more with noningrowth components (30% vs. 5%, P  = .03) and time to revision in patients ultimately requiring allograft reconstruction was significantly later (9.96 vs. 3.68 years, P  = .03)., Conclusion: Central ingrowth pegs on glenoid components were associated with decreased need for structural allograft reconstruction during revision; however, time to revision was earlier in these components. Further research should focus on whether glenoid failure is due to glenoid component design, time to revision, or both., (© 2023 The Author(s).)

Objective: To compare range of motion (ROM) and patient-reported outcomes (PROs) between a structured home exercise program (HEP) and active, supervised physiotherapy (PT) after primary Reverse total shoulder arthroplasty (RTSA) by performing a multicenter randomized clinical trial., Methods: Patients undergoing primary RTSA at 2 centers were randomized to either a HEP group, in which they were given a handout and a rope pulley, or a PT group, in which they were given a standardized prescription. Surgical technique and implants were standardized. At baseline, 6 weeks, 3 months, and 1 year postoperatively, we obtained American Shoulder and Elbow Surgeons scores, Western Ontario Osteoarthritis Scores, visual analogue scale for pain scores, and measured ROM via videotape. On video, ROM was then measured by blinded observers. At all study visits, patients were asked how many days per week they were in PT and how many days a week they completed HEP to determine compliance and crossover. An a priori power analysis suggested 29 patients per group, 56 patients total to detect a difference of 30° in active forward elevation with a power of 0.8 at a 2-sided alpha of 0.05., Results: 89 patients were randomized, 43 to PT, and 46 to HEP. We obtained 1-year PRO follow-up on 83 patients (93%) and ROM follow-up on 73 patients (82%). Nine patients (20%) crossed over from HEP to PT and 2 patients (4%) crossed over from PT to HEP. Complications occurred in 13% of HEP and 17% of PT patients (P = .629). Using mixed models that account for baseline values, there were no significant differences between groups in PROs or ROM at final follow-up., Conclusion: In this 2-center, randomized clinical trial, there were no significant differences in patient outcomes or ROM between HEP and PT after RTSA. These findings suggest that it may not be necessary to recommend PT as a protocol for all patients after RTSA., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Internal rotation in adduction is often limited after reverse total shoulder arthroplasty (rTSA), but the origins of this functional deficit are unclear. Few studies have directly compared individuals who can and cannot perform internal rotation in adduction. Little data on underlying 3D humerothoracic, scapulothoracic, and glenohumeral joint relationships in these patients are available., Methods: Individuals >1-year postoperative to rTSA were imaged with biplane fluoroscopy in resting neutral and internal rotation in adduction poses. Subjects could either perform internal rotation in adduction with their hand at T12 or higher (high, N = 7), or below the hip pocket (low, N = 8). Demographics, the American Shoulder and Elbow Surgeons score, Simple Shoulder Test, and scapular notching grade were recorded. Joint orientation angles were derived from model-based markerless tracking of the scapula and humerus relative to the torso. The 3D implant models were aligned to preoperative computed tomography models to evaluate bone-implant impingement., Results: The Simple Shoulder Test was highest in the high group (11 ± 1 vs. 9 ± 2, P = .019). Two subjects per group had scapular notching (grades 1 and 2), and 3 high group and 4 low group subjects had impingement below the glenoid. In the neutral pose, the scapula had 7° more upward rotation in the high group (P = .100), and the low group demonstrated 9° more posterior tilt (P = .017) and 14° more glenohumeral elevation (P = .047). In the internal rotation pose, axial rotation was >45° higher in the high group (P ≤ .008) and the low group again had 11° more glenohumeral elevation (P = .058). Large rotational differences within subject groups arose from a combination of differences in the resting neutral and maximum internal rotation in adduction poses, not only the terminal arm position., Conclusions: Individuals who were able to perform high internal rotation in adduction after rTSA demonstrated differences in joint orientation and anatomic biases versus patients with low internal rotation. The high rotation group had 7° more resting scapular upward rotation and used a 15°-30° change in scapular tilt to perform internal rotation in adduction versus patients in the low group. The combination of altered resting scapular posture and restricted scapulothoracic range of motion could prohibit glenohumeral rotation required to reach internal rotation in adduction. In addition, inter-patient variation in humeral torsion may contribute substantially to postoperative internal rotation differences. These data point toward modifiable implant design and placement factors, as well as foci for physical therapy to strengthen and mobilize the scapula and glenohumeral joint in response to rTSA surgery., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Reverse total shoulder arthroplasty implantation has increased dramatically over the past 4 decades since it was first introduced in France in 1985. It has greatly improved the ability to treat patients with cuff tear arthropathy, proximal humeral fractures, and osteoarthritis with severe bone loss. However, with the increased implementation of reverse total shoulder arthroplasty, there has been a corresponding rise in complications. Five of the most common complications following reverse total shoulder arthroplasty are instability, scapular fractures, periprosthetic humeral fractures, glenoid baseplate loosening, and infection.

Background: The etiology of adhesive capsulitis involves inflammation, thickening, and fibrosis of the shoulder capsule. The underlying genetic factors are poorly understood. The purpose of this study was to identify genetic variants associated with adhesive capsulitis using the UK Biobank (UKB) cohort and compare them with variants associated with Dupuytren disease investigating a common etiology between the 2 fibrotic disorders., Methods: A genome-wide association study (GWAS) was performed using data from UKB with 10,773 cases of adhesive capsulitis, and a second GWAS was performed with 8891 cases of Dupuytren disease. Next, a comparison of association statistics was performed between adhesive capsulitis and Dupuytren disease using the data from both GWAS. Finally, single-nucleotide polymorphisms (SNPs) previously reported from candidate gene studies for adhesive capsulitis and Dupuytren disease were tested for association with adhesive capsulitis and Dupuytren disease using the summary statistics from their respective GWAS., Results: The UKB GWAS for adhesive capsulitis identified 6 loci that reached genome-wide statistical significance: a cluster of 11 closely linked SNPs on chromosome 1; a single SNP on chromosome 2; a single SNP on chromosome 14; 2 closely linked SNPs on chromosome 21; 33 closely linked SNPs on chromosome 22; and 3 closely linked SNPs on the X chromosome. These SNPs were associated with 8 different genes including TSPAN2/NGF, SATB2, MRPL52/MMP14, ERG, WNT7B, and FGF13. A GWAS for Dupuytren disease was performed and a comparison to the adhesive capsulitis GWAS showed 13 loci significantly associated with both phenotypes. A validation attempt of 6 previously reported SNPs associated with adhesive capsulitis using UKB summary statistics was unable to confirm any of the previously reported SNPs (all P > .19). All 23 previously reported SNPs associated with Dupuytren disease were confirmed using the UKB summary statistics (P < 2.1 × 10 -3 ) CONCLUSION: This GWAS investigating adhesive capsulitis has identified 6 novel loci involving 8 different genes to be associated with adhesive capsulitis. A GWAS investigating Dupuytren disease was performed and compared to the adhesive capsulitis GWAS, and 13 common loci were identified between the 2 disorders with genes involved in pathologic fibrosis. We were unable to validate the SNPs in candidate genes previously reported to be associated with adhesive capsulitis although we were able to confirm all previously reported SNPs associated with Dupuytren disease. The strong genetic overlap between the adhesive capsulitis and Dupuytren disease loci suggests a similar etiology between the 2 diseases., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Reverse shoulder arthroplasty has become the predominant shoulder arthroplasty procedure. Despite newer design modifications, complications still occur after reverse shoulder arthroplasty. Early complications include instability, acromial and scapular spine stress fractures, periprosthetic fractures, periprosthetic joint infections, and neurologic injury. It is important to discuss the diagnosis and management of these early complications.

Background: Although muscle weakness and/or imbalance of the rotator cuff are thought to contribute to the development of shoulder instability, the association between muscular dysfunction and shoulder instability is not completely understood. The purpose of this study was to evaluate rotator cuff and deltoid muscle cross-sectional areas in different types of shoulder instability (anterior, posterior, and multidirectional instability [MDI]) and to determine the associations between muscular imbalance and shoulder instability direction., Methods: Preoperative magnetic resonance images of patients with shoulder instability who subsequently underwent arthroscopic glenohumeral labral repair or capsular plication were evaluated. Shoulder instability was classified into 3 categories by direction: (1) anterior, (2) posterior, and (3) MDI. The rotator cuff (supraspinatus, subscapularis, and infraspinatus + teres minor) and deltoid (anterior and posterior portions, and total) muscle areas were measured on T1 sagittal and axial slices, respectively. The ratios of the subscapularis to infraspinatus + teres minor area and the anterior deltoid to posterior deltoid area were calculated to quantify the transverse force couple imbalance., Results: A total of 189 patients were included, where each group consisted of 63 patients. The infraspinatus + teres minor muscle area was smaller than the subscapularis muscle area in the anterior instability group (P = .007). The subscapularis muscle area was smaller than the infraspinatus + teres minor muscle area in the posterior instability and MDI groups (P ≤ .003). The anterior deltoid muscle area was smaller than the posterior deltoid muscle area in all groups (P ≤ .001). The subscapularis-to-infraspinatus + teres minor area ratio in the anterior instability group (1.18 ± 0.40) was higher than that in the posterior instability and MDI groups (0.79 ± 0.31 and 0.93 ± 0.33, respectively; P < .001). There was no difference in the anterior deltoid-to-posterior deltoid area ratio among the 3 groups., Conclusion: Patients with anterior instability have smaller muscle area of the posterior rotator cuff as compared with the anterior rotator cuff. In contrast, patients with posterior instability and MDI have smaller muscle area of the anterior rotator cuff as compared with the posterior rotator cuff. Thus, the direction of shoulder instability is associated with rotator cuff muscle area., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

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.)

Introduction: Three-dimensional planning of humeral head osteotomy in shoulder arthroplasty (SA) is understudied. This study evaluated whether a standard osteotomy technique along the anterosuperior anatomic neck (ASOT) could be surgically reproduced as pre-operatively planned on 3D-CT models., Material and Methods: Pre-operative planning in 12 cadaver shoulders was performed on a 3D-CT model of the humerus to calculate the planned osteotomy plane (planned OP). The osteotomy was then performed using a free-hand technique, and a post-operative CT scan was obtained for analysis (performed OP). Planes were compared with regards to inclination, retroversion, and resected humeral head thickness so the accuracy could be quantified., Results: The absolute errors between the performed and planned OP were 2° (0-10°), 5° (0-14°), and 4 mm (1-7 mm) for inclination, retroversion, and resected head thickness, respectively. Deviation < 10° for inclination and retroversion and < 5 mm for resected humeral head thickness between planned and performed OP was achieved in 92%, 83%, 58% of cases, respectively. No differences were found for inclination (p = 0.289), whereas retroversion and resected head thickness were smaller than planned (p ≤ 0.027)., Conclusions: Pre-operative planning of the ASOT using a 3D-CT model is accurate within a threshold of 10° when using a free-hand technique in 92% of cases for inclination. Retroversion and resected head thickness differed from the pre-operative plan, thereby limiting the unrestricted use of humeral head osteotomy planning from 3D-CT models in SA. These findings are a reference for further studies to develop and quantify the accuracy of pre-operative planning software including cutting guides for SA using 3D-CT models., Level of Evidence: Basic science article., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: During anatomic total shoulder arthroplasty (aTSA), the humeral head can be resected with or without the use of an intramedullary cutting guide, the former referred to as intramedullary (IM) resection and the latter referred to as freehand (FH) resection. Outcomes following aTSA are predicated upon the restoration of the native humeral anatomy, which can be more challenging with stemless implants. To date, no studies have determined which method of humeral head resection is superior in restoring native anatomy. Our purpose was to determine whether FH or IM resection was superior in restoring native anatomy during aTSA with stemless implants., Methods: A review of all patients who underwent aTSA using the stemless Tornier Simpliciti Shoulder System at two academic institutions by two separate surgeons between January 2017 and June 2020 was performed. One surgeon at one institution performed stemless aTSA using the IM resection technique, while the second surgeon utilized the FH resection technique. Patients were excluded if they underwent surgery for an indication other than glenohumeral osteoarthritis, if they received a short-stem or standard-stem implant, or if they lacked adequate preoperative and postoperative Grashey radiographs. One hundred eleven patients across both institutions (51 IM, 60 FH) were included for the final radiographic assessment. The humeral head height (HH) and neck-shaft angle (NSA) were measured on preoperative and postoperative Grashey radiographs. The centers of rotation (CORs) were measured on postoperative Grashey radiographs. Patients were classified as having acceptable restoration of their native anatomy if the change (Δ) in COR or HH was ≤3 mm and ≤ 5 mm, respectively, or if the postoperative NSA was ≥130°., Results: IM resection had the greatest acceptable restoration of COR (90.2% IM versus 70% FH, P = .009), HH (96.1% IM vs. 63.3% FH, P < .001), and NSA (96.1% IM vs. 78.3% FH, P = .006) relative to FH resection. The mean postoperative NSAs for the IM and FH cohorts were 134.4° (±2.1°) and 133.8° (±5.4°), respectively (P = .208). The mean ΔCORs for the IM and FH groups were 1.2 (±1.5) and 2.3 (±1.2) mm, respectively (P < .001). Finally, the mean ΔHHs for the IM and FH cohorts were 1.7 (±1.4) and 4.4 (±2.9) mm, respectively (P < .001)., Conclusions: Restoration of the native humeral anatomy following stemless aTSA occurred at a significantly higher rate when using IM vs. FH resection., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Reverse total shoulder arthroplasty (rTSA) typically restores active arm elevation. Prior studies in patients with rTSA during tasks that load the arm had limitations that obscured underlying three-dimensional (3D) kinematic changes and the origins of motion restrictions. Understanding the scapulothoracic and glenohumeral contributions to loaded arm elevation will uncover where functional deficits arise and inform strategies to improve rTSA outcomes., Questions/purposes: In a cohort of patients who had undergone rTSA and a control cohort, we asked: (1) Is there a difference in maximum humerothoracic elevation when scapular plane elevation (scaption) is performed with and without a handheld weight? (2) Is maximum humerothoracic elevation related to factors like demographics, patient-reported outcome scores, isometric strength, and scapular notching (in the rTSA group only)? (3) Are there differences in underlying 3D scapulothoracic and glenohumeral motion during scaption with and without a handheld weight?, Methods: Ten participants who underwent rTSA (six males, four females; age 73 ± 8 years) were recruited at follow-up visits if they were more than 1 year postoperative (24 ± 11 months), had a BMI less than 35 kg/m 2 (29 ± 4 kg/m 2 ), had a preoperative CT scan, and could perform pain-free scaption. Data from 10 participants with a nonpathologic shoulder, collected previously (five males, five females; age 58 ± 7 years; BMI 26 ± 3 kg/m 2 ), were a control group with the same high-resolution quantitative metrics available for comparison. Participants in both groups performed scaption with and without a 2.2-kg handheld weight while being imaged with biplane fluoroscopy. Maximum humerothoracic elevation and 3D scapulothoracic and glenohumeral kinematics across their achievable ROM were collected via dynamic imaging. In the same session the American Shoulder and Elbow Surgeons (ASES) score, the Simple Shoulder Test (SST), and isometric strength were collected. Data were compared between weighted and unweighted scaption using paired t-tests and linear mixed-effects models., Results: When compared with unweighted scaption, maximum humerothoracic elevation decreased during weighted scaption for patients who underwent rTSA (-25° ± 30°; p = 0.03) but not for the control group (-2° ± 5°; p = 0.35). In the rTSA group, maximum elevation correlated with the ASES score (r = 0.72; p = 0.02), and weighted scaption correlated with BMI (r = 0.72; p = 0.02) and the SST (r = 0.76; p = 0.01). Scapular notching was observed in three patients after rTSA (Grades 1 and 2). Four of 10 patients who underwent rTSA performed weighted scaption to less than 90° humerothoracic elevation using almost exclusively scapulothoracic motion, with little glenohumeral contribution. This manifested as changes in the estimated coefficient representing mean differences in slopes in the humerothoracic plane of elevation (-12° ± 2°; p < 0.001) and true axial rotation (-16° ± 2°; p < 0.001), scapulothoracic upward rotation (7° ± 1°; p < 0.001), and glenohumeral elevation (-12° ± 1°; p < 0.001), plane of elevation (-8° ± 3°; p = 0.002), and true axial rotation (-11° ± 2°; p < 0.001). The control group demonstrated small differences between scaption activities (< |2°|), but a 10° increase in humerothoracic and glenohumeral axial rotation (both p < 0.001)., Conclusion: After rTSA surgery, maximum humerothoracic elevation decreased during weighted scaption by up to 88° compared with unweighted scaption, whereas 4 of 10 patients could not achieve more than 90° of elevation. These patients exhibited appreciable changes in nearly all scapulothoracic and glenohumeral degrees of freedom, most notably a near absence of glenohumeral elevation during weighted scaption. Patients with rTSA have unique strategies to elevate their arms, often with decreased glenohumeral motion and resultant compensation in scapulothoracic motion. In contrast, the control group showed few differences when lifting a handheld weight., Clinical Relevance: Functional deficiency in activities that load the shoulder after rTSA surgery can affect patient independence, and they may be prevalent but not captured in clinical studies. Pre- or postoperative rehabilitation to strengthen scapular stabilizers and the deltoid should be evaluated against postoperative shoulder function. Further study is required to determine the etiology of deficient glenohumeral motion after rTSA, and the most effective surgical and/or rehabilitative strategies to restore deficient glenohumeral motion after rTSA., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2022 by the Association of Bone and Joint Surgeons.)

Background: It is well known that glenoid osseous defects >13.5% of the glenoid width critically destabilize the shoulder, as do labral tears. Chondrolabral defects often occur with anterior dislocation of the shoulder. It is unclear whether glenoid chondrolabral defects contribute to shoulder stability and, if so, at what size they become critical., Purpose/hypothesis: The purpose of this study was to determine the effect of incremental chondrolabral defect sizes on anterior shoulder stability in the setting of labral deficiency. The hypothesis was that chondrolabral defects ≥13.5% of the glenoid width will decrease anterior shoulder stability., Study Design: Controlled laboratory study., Methods: This controlled laboratory study tested 12 fresh-frozen shoulders. Specimens were attached to a custom testing device in abduction and neutral rotation with 50-N compression applied to the glenoid. The humeral head was translated 10 mm anterior, anteroinferior, and anterosuperior with the conditions of intact cartilage and labrum and anterior full-thickness chondrolabral defects of 3-, 6-, and 9-mm width. Translation force was measured continuously. Peak translation force divided by 50-N compressive force defined the stability ratio. Data were analyzed using analysis of variance., Results: The anterior stability ratio decreased between the intact state (36% ± 7%) and all defects ≥3 mm (≤32% ± 8%; P ≤ .023). The anteroinferior stability ratio decreased between the intact state (52% ± 7%) and all defects ≥3 mm (≤47% ± 7%; P ≤ .006). The anterosuperior stability ratio decreased between the intact state (36% ± 4%) and all defects ≥6 mm (≤33% ± 4%; P ≤ .006). A 3-mm defect equated to 10% of the glenoid width. There were moderate to strong negative correlations between chondrolabral defect size and stability ratio in the anterior, anteroinferior, and anterosuperior directions ( r = -0.79, -0.63, and -0.58, respectively; P ≤ .001). There were moderate to strong negative correlations between the percentage of glenoid chondrolabral defect size to the glenoid width and the stability percentage in all directions ( r = -0.81, -0.63, and -0.61; P ≤ .001)., Conclusion: An anterior glenoid chondrolabral defect ≥3 mm (>10% of the glenoid width) significantly decreased anterior and anteroinferior stability. Chondrolabral defect size negatively correlated with stability., Clinical Relevance: To fully restore glenohumeral stability, in addition to labral repair, it may be necessary to reconstruct chondrolabral defects as small as 3 mm (10% of the glenoid width)., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: R.Z.T. has received consulting fees from Cayenne Medical and Mitek and royalties from Shoulder Innovations, Wright Medical, and Zimmer; he also has stock/stock options in Conextions, Intrafuse, and Kator. P.N.C. has received consulting fees from DJO and DePuy, speaking fees from DePuy, and royalties from DePuy and Responsive Arthroscopy. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2022.)

Background: Although typically favorable in outcome, anatomic total shoulder arthroplasty (aTSA) can require long-term revision. The most common cause for revision is glenoid loosening, which may result from eccentric cyclic forces and joint translations. "Rocking" of the glenoid component may be exacerbated by the joint geometry, such as glenoid inclination and version. Restoration of premorbid glenoid inclination may be preferable, although laboratory and computational models indicate that both superior inclination and inferior inclination have benefits. This discrepancy may arise because previous studies were limited by a lack of physiological conditions to test inclination. Therefore, a cadaveric shoulder simulator with 3-dimensional human motion was used to study joint contact and muscle forces with isolated changes in glenoid inclination., Methods: Eight human cadaveric shoulders were tested before and after aTSA. Scapular-plane abduction kinematics from human subjects were used to drive a cadaveric shoulder simulator with 3-dimensional scapulothoracic and glenohumeral motion. Glenoid inclination was varied from -10° to +20°, whereas compressive, superior-inferior shear, and anterior-posterior shear forces were collected with a 6-df load cell during motion. Outputs also included muscle forces of the deltoid and rotator cuff. Data were evaluated with statistical parametric mapping repeated-measures analysis of variance and t tests., Results: Inferior glenoid inclination (-10°) reduced both compressive and superior-inferior shear forces vs. neutral 0° inclination by up to 40%, and even more when compared with superior inclination (P < .001). Superior inclinations (+10° and +20°) tended to increase deltoid and rotator cuff forces vs. neutral 0° inclination or inferior inclination, on the order of 20%-40% (P ≤ .045). All force metrics except anterior-posterior shear were lowest for inferior inclination. Most aTSA muscle forces for neutral 0° inclination were not significantly different from native shoulders and decreased 45% and 15% in the posterior deltoid and supraspinatus, respectively (P ≤ .003). Joint translations were similar to prior reports in aTSA patients and did not differ between any inclinations or compared with native shoulders. Joint reaction forces were similar to those observed in human subjects with instrumented aTSA implants, providing confidence in the relative magnitude of our results., Conclusions: Inferior inclination reduces overall forces in the shoulder. Superior inclinations increase the muscle effort required for the shoulder to achieve similar motion, thus increasing the forces exerted on the glenoid component. These results suggest that a preference toward aTSA glenoid components in inferior inclination may reduce the likelihood of glenoid loosening by reducing excessive muscle and joint contact forces., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Purpose: To determine the likelihood of, and risk factors for, progression of rotator cuff tendinopathy to tear on magnetic resonance imaging (MRI) in patients treated conservatively for minimum 1 year., Methods: Patients in the Veterans Health Administration (VHA) Corporate Data Warehouse with a diagnosis of rotator cuff injury and sequential MRI of the same shoulder at least 1 year apart were identified. Presenting MRIs were reviewed to select patients with tendinopathy, while excluding those with a normal appearing cuff, tear, or prior repair. Tear progression was defined as development of a partial or full-thickness tear on follow-up MRI. Chart review was performed for demographic and clinical data. Descriptive statistics and inter-observer and intra-observer reliability were calculated. Discrete and continuous variables were compared between patients who progressed and those who did not using chi-square, Fisher's Exact, Student's t , and Mann-Whitney U -test., Results: In the VHA database, 135 patients had an initial MRI demonstrating rotator cuff tendinopathy. On subsequent MRI at mean 3.4 year follow-up, 39% of patients had progressed to a tear. When grouped on the basis of time between scans as 1 to 2 years, 2 to 5 years, or over 5 years, the rate of progression was 32%, 37%, and 54% respectively. No factors were associated with progression., Conclusions: Among patients with symptomatic rotator cuff tendinopathy that remained symptomatic at a minimum of 1 year and obtained a follow-up MRI, 39% progressed to a partial or full-thickness tear. None of the factors evaluated in this study correlated with progression from tendinopathy to tear. When patients were grouped based on time between scans as 1 to 2 years, 2 to 5 years, or more than 5 years, the rate of progression from tendinopathy to tear was 32%, 37%, and 54%, respectively., (© 2022 The Authors.)

Innovations currently available with anatomic total shoulder arthroplasty include shorter stem designs and augmented/inset/inlay glenoid components. Regarding reverse shoulder arthroplasty (RSA), metal augmentation, including custom augments, on both the glenoid and humeral side have expanded indications in cases of bone loss. In the setting of revision arthroplasty, humeral options include convertible stems and newer tools to improve humeral implant removal. New strategies for treatment and surgical techniques have been developed for recalcitrant shoulder instability, acromial fractures, and infections after RSA. Finally, computer planning, navigation, PSI, and augmented reality are imaging options now available that have redefined preoperative planning and indications as well intraoperative component placement. This review covers many of the innovations in the realm of shoulder arthroplasty.

Background: The purpose of the present study was to analyze the association between sex hormone deficiency and rotator cuff repair (RCR) with use of data from a large United States insurance database., Methods: A retrospective analysis of insured subjects from the Truven Health MarketScan database was conducted, collecting data for RCR cases as well as controls matched for age, sex, and years in the database. Multivariable logistic regression models adjusted for matching variables were utilized to compare RCR status with estrogen deficiency status and testosterone deficiency status. These associations were confirmed with use of data from the Veterans Genealogy Project database, with which the relative risk of RCR was estimated for patients with and without sex hormone deficiency., Results: The odds of RCR for female patients with estrogen deficiency were 48% higher (odds ratio, 1.48; 95% confidence interval, 1.44 to 1.51; p < 0.001) than for those without estrogen deficiency. The odds of RCR for males with testosterone deficiency were 89% higher (odds ratio, 1.89; 95% confidence interval, 1.82 to 1.96; p < 0.001) than for those without testosterone deficiency. Within the Veterans Genealogy Project database, the relative risk of estrogen deficiency among RCR patients was 2.58 (95% confidence interval, 2.15 to 3.06; p < 0.001) and the relative risk of testosterone deficiency was 3.05 (95% confidence interval, 2.67 to 3.47; p < 0.001)., Conclusions: Sex hormone deficiency was significantly associated with RCR. Future prospective studies will be necessary to understand the pathophysiology of rotator cuff disease as it relates to sex hormones., Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/G944)., (Copyright © 2022 by The Journal of Bone and Joint Surgery, Incorporated.)

Case: A 70-year-old male patient presented with anterior deltoid weakness from Parsonage-Turner neuropathy status post failed nerve transfer and a failed total shoulder arthroplasty with pseudoparalysis. The patient underwent revision to a reverse total shoulder arthroplasty with concomitant pectoralis major transfer to substitute for the anterior deltoid. An excellent functional result was attained as early as 6 weeks after surgery., Conclusion: Pectoralis major transfer can be an effective treatment option for isolated anterior deltoid insufficiency, even in the setting of a reverse total shoulder arthroplasty., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/B858)., (Copyright © 2022 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose: To determine the likelihood of and risk factors for tear progression among patients with a symptomatic partial or full-thickness rotator cuff tears (RCTs) who return with continued shoulder pain and obtain subsequent magnetic resonance imaging (MRI) and to identify various patient factors and MRI findings associated with rotator cuff tear progression., Methods: We performed a retrospective review of MRI studies from Veteran's Affair patients with conservatively treated partial- or full-thickness rotator cuff tears. Patient characteristics and demographics were obtained via chart review. Tear characteristics were measured on MRI obtained a minimum of 1 year apart. We defined progression as either (1) an increase from a partial to a full-thickness tear or (2) an increase in tear width or retraction of at least 5 mm. Statistical analysis using χ 2 , Fisher exact, Student t , and Mann-Whitney U test was then performed as appropriate, looking for factors involved in RCT progression., Results: We evaluated 412 MRI studies from 206 Veteran's Affair patients with conservatively treated partial- or full-thickness rotator cuff tears from October 1999 to March 2020. Overall, 61% of RCTs had progressed at a mean of 3.2 ± 2.3 years follow-up. Among all patients, 74% of full-thickness tears progressed in size, 42% of partial-thickness tears progressed in size, and 29% of partial-thickness tears progressed to full-thickness tears. On univariate analysis, full-thickness tears ( P < .001), disruption of the anterior rotator cuff cable ( P  = .001), subscapularis involvement ( P  = .004), tear retraction ( P < .001), and tear width ( P < .001) all increased the likelihood of progression. On multivariate analysis, full-thickness tears ( P < .001) and subscapularis involvement ( P  = .045) were correlated with progression., Conclusions: RCTs progress over time in terms of size of tear and from partial- to full-thickness tears. There is an increased risk of tear progression in patients with full-thickness tears when compared with partial-thickness tears along with subscapularis tear involvement. Rates of progression are larger than previously reported rates for both partial- and full-thickness tears, noting that our study population were those patients who continued to be symptomatic from their tears., Level of Evidence: Level IV, prognostic case series., (© 2022 The Authors.)

Background: Although nonoperative treatment is effective for degenerative rotator cuff tears (RCTs), it remains unclear whether the delay created by a trial of nonoperative treatment negatively influences the outcome of a subsequent surgical repair. In March 2020, the COVID-19 pandemic resulted in an involuntary delay in the surgical treatment of rotator cuff disease, creating a natural experiment. The purpose of this study was to evaluate the outcomes and healing of patients who underwent delayed surgical treatment of chronic degenerative RCTs as compared with the nondelayed surgical treatment of RCTs., Methods: This was a prospective study of two groups: patients planned to undergo arthroscopic rotator cuff repair between March 16, 2020 and May 1, 2020-the end of the ban on elective surgery-and patients who underwent rotator cuff repair starting six weeks after the ban on elective surgery had been lifted. Preoperatively and at six months postoperatively, we collected the Simple Shoulder Test, the American Shoulder and Elbow Surgeons (ASES) score, and the visual analog scale for pain. We also obtained magnetic resonance imaging (MRI) at six months postoperatively. A power analysis was conducted, and assuming a mean ± standard deviation ASES score of 93.1 ± 13.9 points and a minimum clinically important difference in the ASES score of 27.1 points, 7 patients per group (14 patients in total) would be necessary to have 90% chance of finding a difference., Results: We included 15 patients within each group and obtained 100% follow-up at six months. In the delay group, the mean ± standard deviation delay was 63 ± 24 days. There were no significant preoperative differences between groups in demographics or tear characteristics. Intraoperatively, there were no differences between groups in repair characteristics. Using a repeated-measures analysis of variance, there were significant preoperative vs. postoperative differences in ASES scores ( P  < .001), visual analog scale scores ( P  < .001), and Simple Shoulder Test scores ( P  < .001), but no differences between groups ( P  = .910, .519, and 0.852, respectively). On MRI, within the delay group, 58% had healed, whereas within the control group, 85% had healed ( P  = .202)., Conclusion: COVID-19 caused a two-month delay in the operative treatment of RCTs. This delay did not significantly alter patient-reported outcomes. This delay resulted in a 27% difference in MRI healing rates, which was not statistically significant in this small study. Larger studies should be conducted as our results suggest that a delay in treatment may negatively impact healing rates., (© 2021 The Authors.)

Background: Historically, imaging osseous detail in three dimensions required a computed tomography (CT) scan with ionizing radiation that poorly visualizes the soft tissues. The purpose of this study was to determine the accuracy and reliability of ultrashort echo time (UTE) magnetic resonance imaging (MRI) in measuring humeral cortical thickness and cancellous density as compared with CT., Methods: This was a comparative radiographic study in nine cadavers, each of which underwent CT and UTE MRI. On images aligned to the center of the humeral shaft, anterior, posterior, medial, and lateral humeral cortical thickness was measured 5, 10, and 15 cm distal to the top of the head. Cancellous density was measured as signal within a 1-cm diameter region of interest in the center of the head, the subtuberosity head, the subarticular head, and the subarticular glenoid vault. Glenoid cortical thickness was measured at the center of the glenoid. Cortical measurements were compared using mean differences and 95% confidence intervals, paired Student's t-tests, and intraclass correlation coefficients (ICCs). We compared cancellous measurements using Pearson's correlation coefficients. For all measurements, we calculated interobserver and intraobserver reliability using ICCs with 0.75 as the lower limit for acceptability., Results: With regard to accuracy, for humeral cortical thickness measurements, there were no significant differences between MRI and CT measures, and ICCs were >0.75. The glenoid cortical thickness ICC was <0.75. There was no significant correlation between the cancellous signal on MRI and on CT in any region. For both MRI and CT, interobserver reliability and intraobserver reliability were acceptable (ie, >0.75) for almost all humeral cortical thickness measures., Conclusion: UTE MRI can reliably and accurately measure humeral cortical thickness, but cannot accurately measure cancellous density or accurately and reliably measure glenoid cortical thickness., (© 2021 The Authors.)

Estrogen deficiency has been shown to negatively influence rotator cuff tendon healing. Therefore, the addition of an estrogen-like-compound (ELC) in a nonestrogen-deficient animal may improve the quality of a rotator cuff repair. The purpose of this study was to evaluate the effects of an ELC, diethylstilbestrol (DES), on tendon healing in a murine rotator cuff repair model. Thirty-three male wild-type mice (C57BL/6NJ) were randomly divided into three study groups. Group 1-unoperated mice with normal rotator cuff tendons. Groups 2 and 3 consisted of surgically repaired rotator cuff tendons; Group 2 (repair-only) was the standard repair group (no DES injected), whereas Group 3 (repair + DES) was the experimental repair group (injected with DES). Comparing the maximal thickness of calcified fibrocartilage to uncalcified fibrocartilage, the ratios for the control (intact tendon), repair-only, and repair + DES groups were 2:1, 0.9:1, and 1.7:1. RNA expression data demonstrated upregulation of chondrogenic, angiogenic, and tendon modulation genes in the repair- only group compared to the control (intact tendon) group (p < 0.04 for all), and that addition of DES further increased the osteogenic, angiogenic, and tendon modulation gene expression compared to the repair-only group (p < 0.02). Immunohistochemical analysis indicated that the addition of DES further increased osteogenic, angiogenic, and tendon maturation protein expression at the enthesis compared to standard repairs., (© 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Background: Computer assisted planning without patient specific instrumentation may be utilized to guide reverse total shoulder arthroplasty baseplate placement. The purpose of this study was to determine the difference between planned and achieved inclination and retroversion correction with three-dimensional preoperative computer assisted planning in reverse total shoulder arthroplasty without patient specific instrumentation with bone grafting for severe glenoid erosion., Methods: Preoperative three-dimensional computer assisted planning without patient specific instrumentation was performed on 15 patients undergoing primary reverse total shoulder arthroplasty with glenoid bone grafting for severe glenoid erosion. On preoperative and immediate postoperative computed tomography slices, two-dimensional retroversion and inclination were measured. Preoperative three-dimensional baseline retroversion and inclination and planned postoperative three-dimensional retroversion and inclination were measured. Planned and achieved version and inclination changes were compared., Results: The planned and achieved retroversion corrections were 18° and 12°, respectively (p < 0.001). The planned and achieved inclination corrections were 11° and 11°, respectively (p = 0.803)., Conclusions: Three-dimensional computer assisted planning without patient specific instrumentation in the setting of reverse total shoulder arthroplasty with severe glenoid erosion requiring bone grafting can accurately guide baseplate placement. All cases in which failure to correct retroversion or inclination within 10° of planning occurred in patients with severe erosion (B3 or E3 glenoids), therefore patient specific guides may be warranted in these cases to improve accuracy of implantation., Level of Evidence: Level IV, retrospective case series., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: PNC is a paid consultant for DePuy-Mitek and Arthrex. LB and IS declare that they have no conflicts of interest in the authorship or publication of this contribution. RZT is a paid consultant for Zimmer Biomet, Wright Medical, and Depuy-Mitek; has stock in Conextions, INTRAFUSE, Genesis, and KATOR; receives intellectual property royalties from Wright Medical, Shoulder Innovations, and Zimmer Biomet; receives publishing royalties from Springer, the Journal of Bone and Joint Surgery and the Journal of the American Association of Orthopaedic Surgeons, and serves on the editorial board for the Journal of the American Association of Orthopaedic Surgeons., (© 2020 The British Elbow & Shoulder Society.)

Purpose: To describe patient-reported outcomes following simple elbow dislocation and to identify the baseline factors that predict outcomes., Methods: Adult patients treated with a closed reduction for a simple elbow dislocation with or without minor fracture (coronoid avulsion, radial head fracture, or epicondyle avulsion) from 2000 to 2018 completed outcome instruments including Disabilities of the Arm, Shoulder and Hand ( Quick DASH) via Research Electronic Data Capture. Descriptive statistics were calculated. Univariate followed by multivariate Tobit regression models were used to determine factors associated with clinical outcomes on Quick DASH. Social deprivation was measured using the Area Deprivation Index. Patients with additional upper-extremity injuries or associated major fractures (Monteggia or terrible triad injuries, distal humerus fractures, etc) were excluded., Results: At a mean follow-up of 67.5 months, 95% (38/40) of patients reported satisfaction with treatment, and clinical outcomes were good ( Quick DASH 9.0 ± 14.8). Univariate analysis showed that higher Area Deprivation Index, older age, female sex, high-energy mechanism of injury, and worker's compensation (WC) or Medicare insurance status (vs commercial) was associated with significantly worse Quick DASH scores at follow-up. Early therapy, dominant elbow involvement, presence of minor fractures (minimally displaced radial head, coronoid tip, or epicondylar avulsion fractures), race, and treating service did not influence outcomes in univariate analyses. Multivariate analysis demonstrated a significant association between increased social deprivation, WC insurance, and Medicare insurance and worse Quick DASH scores while controlling for new upper-extremity injury, age, sex, and mechanism of injury., Conclusions: Outcomes and treatment satisfaction following simple elbow dislocation are generally good but are significantly worse for the patients with greater levels of social deprivation and WC or Medicare insurance. Although surgeons should be aware of the possibility that specific subsets of patients may benefit from early therapy, this factor did not appear to influence long-term outcomes in this small cohort., Type of Study/level of Evidence: Prognostic III., Competing Interests: Declaration of interests: No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.

Background: The purpose of the study was to identify genetic variants associated with rotator cuff disease by performing a genome-wide association study (GWAS) for shoulder impingement using the UK Biobank (UKB) cohort and then combining the GWAS data with a prior GWAS for rotator cuff tears. The loci identified by the GWAS and meta-analysis were examined for changes in expression following rotator cuff tearing using RNA sequencing., Methods: A GWAS was performed using data from UKB with 3864 cases of shoulder impingement. The summary statistics from shoulder impingement and a prior study on rotator cuff tears were combined in a meta-analysis. Also, the previous association of 2 single-nucleotide polymorphisms (SNPs) with shoulder impingement from a published GWAS using the UKB was tested. Rotator cuff tendon biopsies were obtained from 24 patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair (cases) and 9 patients who underwent open reduction internal fixation for a proximal humeral fracture (controls). Total RNA was extracted and differential gene expression was measured by RNA sequencing for genes with variants associated with rotator cuff tearing., Results: The shoulder impingement GWAS identified 4 new loci: LOC100506457, LSP1P3, LOC100506207, and MIS18BP1/LINC00871. Combining data with a prior GWAS for rotator cuff tears in a meta-analysis resulted in the identification of an additional 7 loci: SLC39A8/UBE2D3, C5orf63, ASTN2, STK24, FRMPD4, ACOT9/SAT1, and LINC00890/ALG13. Many of the identified loci have known biologic functions or prior associations with diseases, suggesting possible biologic pathways leading to rotator cuff disease. RNA sequencing experiments show that expression of STK24 increases whereas expression of SAT1 and UBE2D3 decreases following rotator cuff tearing. Two SNPs previously reported to show an association with shoulder impingement from a prior UKB GWAS were not validated in our study., Conclusion: This is the first GWAS for shoulder impingement in which new data from UKB enabled the identification of 4 loci showing a genetic association. A meta-analysis with a prior GWAS for rotator cuff tearing identified an additional 7 loci. The known biologic roles of many of the 11 loci suggest plausible biologic mechanisms underlying the etiology of rotator cuff disease. The risk alleles from each of the genetic loci can be used to assess the risk for rotator cuff disease in individual patients, enabling preventative or restorative actions via personalized medicine., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

To improve understanding of the pathophysiology of rotator cuff repair and develop therapeutic treatments an animal model is essential. This Technical Note describes a comprehensive step-by-step description of rotator cuff repair in the mouse. This technique is particularly beneficial because the murine rotator cuff is anatomically similar to that of humans. The mouse model can also be used to test the biological role of candidate genes during repair and be used to identify drugs that accelerate the healing process., (© 2021 by the Arthroscopy Association of North America. Published by Elsevier.)

Competing Interests: Disclosure: The author indicated that no external funding was received for any aspect of this work. On the Disclosure of Potential Conflicts of Interest form, which is provided with the online version of the article, the author checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work (http://links.lww.com/JBJS/G372).

Background: Diabetes mellitus (DM) may be associated with the etiology of rotator cuff disease; however, its effect on healing after surgical rotator cuff repair (RCR) is not well characterized. The purposes of this study are to analyze the association between DM and surgical RCR, the association between DM and revision RCR after RCR, and the association between DM and the cost of RCR., Methods: A retrospective analysis of claims data of privately and publicly insured subjects from the Truven Health MarketScan database from 2008 to 2017 was conducted, collecting RCR cases and controls matched for age, sex, year of RCR, and first and last year in the database. Multivariable logistic regression models were used to compare DM incidence within the RCR and control groups after adjusting for all matching variables plus region, insurance plan type, tobacco use, and Charlson comorbidity index (CCI). Cox proportional hazard models were used to compare rates of revision RCR between DM and non-DM groups after adjusting for patient age, sex, year of RCR, plan type, and CCI. Generalized estimating equations were used to analyze RCR cost, and exponentiated regression coefficients were reported to represent cost ratios., Results: The full analysis cohort consisted of 292,666 RCR cases and matched controls. The adjusted odds of having RCR surgery in diabetic patients was 48% higher (odds ratio = 1.48 [95% confidence interval {CI} 1.46 to 1.51], P < .001) than nondiabetics. DM was not significantly associated with revision RCR after RCR when adjusting for age, sex, region, plan type, tobacco use, year of RCR, and CCI (hazard ratio = 1.03, 95% CI 0.99 to 1.07, P  = .17). Diabetes was associated with a higher cost of RCR by 3% (ratio = 1.03, 95% CI 1.02 to 1.03, P < .001)., Conclusions: Diabetic patients are at a higher risk of undergoing RCR surgery; however, there is no association between DM and subsequent rotator cuff revision surgery., (© 2021 The Authors.)

Background: Restoration of muscular strength is predicated on restoration of muscle length. The purpose of this study was to describe infraspinatus and deltoid length preoperative to reverse total shoulder arthroplasty (RTSA) to guide distalization and lateralization to restore preoperative muscle length., Methods: This was a retrospective radiographic study. We measured the infraspinatus length on preoperative computed tomographic images and the deltoid length on preoperative radiographs. For all measurements, reliability was first established by comparing measurements between 2 observers, and intraclass correlation coefficients (ICCs) were calculated. We then calculated descriptive statistics for these muscle lengths and developed a formula to predict these muscle lengths from patient demographics., Results: We measured infraspinatus length in 97 patients and deltoid length in 108 patients. Inter-rater reliability was excellent, with all ICCs >0.886. The mean infraspinatus length was 15.5 cm (standard deviation 1.3) and ranged from 12.6-18.9 cm, whereas the deltoid length was 16.2±1.7 cm and ranged from 12.5-20.2 cm. Both infraspinatus (r = 0.775, P < .001) and deltoid length (r = 0.717, P < .001) were highly correlated with patient height but did not differ between diagnoses. Formulae developed through linear regression allowed prediction of muscle length to within 1 cm in 78% and within 2 cm in 100% for the infraspinatus and 60% and 88% for the deltoid., Conclusion: Deltoid and infraspinatus length are variable but highly correlated with patient height. To maintain tension, 2 mm of lateralization and distalization should be added for every 6 inches (∼15 cm) of height above average for a Grammont-style RTSA., (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 determine the association between glenohumeral osteoarthritis (GHOA) and three-dimensional acromial and glenoid morphology., Methods: In this retrospective study, we compared computed tomographic studies of three groups of scapulae: normal healthy, mild GHOA (Samilson-Prieto grade 1), and severe GHOA (Samilson-Prieto grade 3). All scans were segmented to create three-dimensional reconstructions. From these models, critical shoulder angle and acromial offset were measured, as normalized to scapular height. The coronal plane inclination of the glenoid was measured using a glenoid sphere-fit method. Reliability was confirmed via intraclass correlation coefficients > 0.75., Results: Eighty scapulae were included: 30 normal, 20 mild GHOA, and 30 severe GHOA. There were no differences in acromial offset between the normal group and either the mild-GHOA group or the severe-GHOA group. The severe-GHOA group had a smaller critical shoulder angle than either the normal (30 ± 5° vs. 34 ± 4°, P  = .003) or mild-GHOA groups (34 ± 4°, P  = .020), but the normal and mild-GHOA groups did not differ ( P  = .965). The severe-GHOA group had more inferiorly inclined glenoids than either the normal (7 ± 6° vs. 12 ± 5°, P  = .002) or mild-GHOA groups (14 ± 5°, P  ≤ .001), but the normal and mild-GHOA groups did not differ ( P  = .281)., Conclusion: Normal and severe-GHOA shoulders differ in critical shoulder angle and glenoid inclination but not acromial offset. The lack of a difference in critical shoulder angle or inferior inclination between mild-GHOA and normal groups calls into question whether inclination and critical shoulder angle differences predate severe GHOA., (© 2021 The Author(s).)

Age affects gross shoulder range of motion (ROM), but biomechanical changes over a lifetime are typically only characterized for the humerothoracic joint. Suitable age-related baselines for the scapulothoracic and glenohumeral contributions to humerothoracic motion are needed to advance understanding of shoulder injuries and pathology. Notably, biomechanical comparisons between younger or older populations may obscure detected differences in underlying shoulder motion. Herein, biplane fluoroscopy and skin-marker motion analysis quantified humerothoracic, scapulothoracic, and glenohumeral motion during 3 static poses (resting neutral, internal rotation to L4-L5, and internal rotation to maximum reach) and 2 dynamic activities (scapular plane abduction and external rotation in adduction). Orientations during static poses and rotations during active ROM were compared between subjects <35 years and >45 years of age (N = 10 subjects per group). Numerous age-related kinematic differences were measured, ranging 5-22°, where variations in scapular orientation and motion were consistently observed. These disparities are on par with or exceed mean clinically important differences and standard error of measurement of clinical ROM, which indicates that high resolution techniques and appropriately matched controls are required to avoid confounding results of studies that investigate shoulder kinematics. Understanding these dissimilarities will help clinicians manage expectations and treatment protocols where indications and prevalence between age groups tend to differ. Where possible, it is advised to select age-matched control cohorts when studying the kinematics of shoulder injury, pathology, or surgical/physical therapy interventions to ensure clinically important differences are not overlooked., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: The etiology of rotator cuff tearing is likely multifactorial, including a potential genetic predisposition. The purpose of the study was to identify genetic variants associated with rotator cuff tearing utilizing the UK Biobank (UKB) cohort, confirm variants using a separate genetic database, and evaluate tissue expression of genes with associated variants following rotator cuff tearing using RNA sequencing., Methods: Genome-wide association study (GWAS): A GWAS was performed using data from UKB with 5701 cases of rotator cuff injury. RNA sequencing analyses: rotator cuff biopsies were obtained from 24 patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair (cases) and 9 patients who underwent open reduction internal fixation for a proximal humerus fracture (controls). Total RNA was extracted and differential gene expression was measured by RNAseq for genes with variants associated with rotator cuff tearing., Results: The results of the UKB GWAS identified 3 loci that reached genome-wide statistical significance: 2 loci on chromosome 7 in GLCCI1 (rs4725069; P = 5.0E-09) and THSD7A (rs575224171; P = 5.3E-09), and 1 locus on chromosome 2 in ZNF804A (rs775583810; P = 3.9E-09). The association with rotator cuff injury of the GLCCI1 single-nucleotide polymorphism (SNP; rs4725069) was confirmed in the Kaiser Permanente Research Bank cohort (P = .008). Twenty previously reported SNPs in 12 genes were evaluated using summary statistics from the UKB GWAS, which confirmed 3 SNPs in TNC with rotator cuff injury (rs1138545, rs72758637, and rs7021589; all P < .0024). Of 17 genes with variants associated with rotator cuff injury (14 previously from literature plus 3 new genes from current UKB GWAS), TIMP2, Col5A1, TGFBR1, and TNC were upregulated (P < .001 for all) and THSD7A was downregulated (P = .005) in tears vs. controls in the RNA sequencing data set., Conclusion: The UKB GWAS has identified 3 novel loci associated with rotator cuff tearing (ZNF804A, GLCCI1, THSD7A). Expression of the THSD7A gene was significantly downregulated in rotator cuff tears vs. controls supporting a potential functional role. Three previously reported SNPs in the TNC gene were validated in the UKB GWAS, supporting a role for this gene in rotator cuff tearing. Finally, TIMP2, Col5A1, TGFBR1, and TNC genes were found to have significantly upregulated tissue expression in cases vs. controls supporting a biologic role in tearing for these genes., (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 determine whether greater tuberosity morphology (1) could be measured reliably on magnetic resonance imaging (MRI), (2) differed between patients with rotator cuff tears (RCTs) compared with those without tears or glenohumeral osteoarthritis, or (3) differed between patients with rotator cuff repairs (RCR) who healed and those that did not., Methods: This is a retrospective comparative study. (1) We measured greater tuberosity width (coronal and sagittal), lateral offset, and angle on MRI corrected into the plane of the humerus. To determine reliability, these measurements were made by two observers and intraclass correlation coefficients were calculated. (2) We compared these measurements between patients with a full-thickness RCT and patients aged >50 years without evidence of a RCT or glenohumeral osteoarthritis. (3) We then compared these measurements between those patients with healed RCRs and those with evidence of retear on MRI. In this portion, we only included patients with both a preoperative and postoperative MRI at least 1 year from RCR. Postoperative MRIs were obtained to assess healing rates, not because of concern for failure. Those without tendon defects were considered healed., Results: (1) In a validation cohort of 50 patients with MRI, all inter-rater intraclass correlation coefficients were greater than 0.75. (2) There were no differences between our RCT group of 110 patients and our comparison group of 100 patients in tuberosity coronal width, sagittal width, or lateral offset. The RCT group had a significantly smaller greater tuberosity angle (63 ± 4° vs 65 ± 5°, P  = .003). (3) In our group of 110 RCRs, postoperative MRI scans were obtained at a mean follow-up of 23.6 ± 15.7 months showing 84 (76%) patients had healed RCRs. Larger coronal tuberosity width was associated with healing (1.3 ± 0.2 vs 1.2 ± 0.2 cm, P  = .032), as was smaller tear width ( P  < .001), and retraction ( P  < .001). When coronal width was dichotomized, there was a significantly higher healing rate with a width over 1.2 cm (85 vs 66%, P  = .02). No other greater tuberosity morphological characteristics were associated with RCR or postoperative healing., Conclusion: RCTs do not appear to be associated with greater tuberosity morphology. Postoperative rotator cuff healing based on MRI is 76%. Higher rates of healing occur with a wider coronal tuberosity width (ie, rotator cuff tendon footprint). Consideration could be given to widening the footprint intraoperatively in an effort to improve healing rates although this remains to be validated., (© 2021 The Authors.)

Background: The purpose of this study was to determine the factors associated with outcomes after reverse total shoulder arthroplasty (RTSA)., Methods: We retrospectively evaluated all RTSAs performed by the senior author between January 1, 2007, and November 1, 2017. We evaluated pain visual analog scale (VAS), Simple Shoulder Test (SST), and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores and complication and reoperation rates at a minimum of 2-year follow-up. We evaluated preoperative and 2-week postoperative radiographs for glenoid inclination (GI), medialization as distance between the center of the humeral head or glenosphere and the line of the deltoid, and distalization via the acromial-greater tuberosity distance. We performed inter- and intrarater reliabilities via intraclass correlation coefficients (ICCs) and conducted a multivariable analysis., Results: We included 230 RTSAs in the analysis, with 70% follow-up at a median of 3.4 years. Reliability was acceptable with all ICCs >.678. Increased postoperative GI was significantly associated with increased VAS pain postoperatively (P = .008). Increased distalization was associated with an increased rate of complications and reoperations (P = .032). Younger age (P = .008), female gender (P = .009), and lower body mass index (BMI) (P = .006) were associated with worse ASES scores. Female gender (P < .001) and lower BMI (P = .039) were associated with worse SST scores. Female gender (P = .013) and lower BMI (P = .005) were associated with worse VAS-pain scores., Conclusion: Age, gender, and BMI are associated with outcome after RTSA. In this retrospective analysis of a Grammont-style RTSA, superior inclination is associated with increased pain postoperatively, whereas excessive arm lengthening is associated with increased risk for complication or reoperation., (Copyright © 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The etiologies of glenohumeral osteoarthritis (GHOA) and eccentric glenoid wear within GHOA are unknown, but muscular imbalance may play a role. The purpose of the present study was to determine the relationship between deltoid muscle area, GHOA, and eccentric glenoid wear. We hypothesized that patients with GHOA would have overall deltoid atrophy as compared with controls and that increasing posterior deltoid areas would associate with glenoid retroversion in the Walch B-type (eccentric) GHOA group., Methods: The study was a retrospective review of computed tomography imaging studies. We included a control group of subjects without GHOA and a group of individuals with GHOA before undergoing total shoulder arthroplasty. We assigned Walch types via consensus. Cross-sectional area was measured for the anterior and posterior deltoid musculature demarcated via the scapular line, normalized to the total deltoid area. Absolute and normalized total, anterior, and posterior deltoid areas were compared between controls and the entire GHOA group. Normalized anterior and posterior deltoid areas were compared between Walch A-type and B-type GHOA patients within the GHOA group. Univariate linear regression was used to evaluate for an association between glenoid retroversion and normalized posterior deltoid areas in controls, Walch A-type, and Walch B-type patients. Multivariate linear regression analysis was used to evaluate the effects of normalized posterior deltoid area, age, sex, and height on glenoid retroversion within the Walch B-type subgroup., Results: We included 99 patients with GHOA and 47 controls. The control and GHOA patients did not differ in absolute deltoid areas (21.8 ± 8.8cm 2 vs. 20.6 ± 7.9cm 2 ; P  = .488). Patients with GHOA had a statistically significant increase in normalized posterior deltoid area (0.50 ± 0.10 vs. 0.46 ± 0.10; P  = .032) and a reciprocal decrease in normalized anterior deltoid area (0.50 ± 0.10 vs. 0.54 ± 0.10; P  = .040) compared with controls. Walch A-type and B-type patients did not differ in normalized posterior deltoid areas (0.50 ± 0.11 vs. 0.50 ± 0.10; P  = .780). Normalized posterior deltoid area positively associated with glenohumeral retroversion in Walch B-type GHOA (R 2  = 0.102; P  = .020), a relationship maintained in multivariate linear regression, using gender, age, and height as covariates (standardized beta = 0.309, P  = .027)., Conclusion: GHOA is not associated with deltoid atrophy, calling into question the suggestion that periarticular muscular atrophy in GHOA is secondary to disuse. Increasing normalized posterior deltoid area associates with increased glenoid retroversion in patients with Walch B-type glenoid morphology. Muscular imbalance may play a role in the etiology or progression of the glenoid deformity observed in eccentric GHOA., (© 2020 The Authors.)