Background Obesity is a well-established risk factor for complications after total shoulder arthroplasty (TSA), and morbidly obese patients may be denied surgery due to concerns about poor outcomes. In the current healthcare climate, patient-reported outcome measures (PROM) are increasingly used to define success after elective orthopedic procedures. Most studies on TSA in obese patients focus on objective metrics such as complication rates, range of motion, and radiographic parameters, while data on the subjective patient experience remain limited. The purpose of this study is to examine the effects of increasing obesity and BMI on patient reported outcome measures (PROM) and satisfaction in obese patients undergoing primary TSA. Methods There were 2,525 patients with a body mass index (BMI) > 30 kg/m2 who underwent primary anatomic or reverse TSA that were identified in a prospective international shoulder registry and stratified according to the World Health Organization (WHO) classification for obesity. Patient demographics, preoperative and minimum 2-year postoperative PROM, patient satisfaction scores, and complications and revisions were compared between patients with Class I (BMI 30–34.99 kg/m2), Class II (BMI 35–39.99), and Class III (BMI > 40 kg/m2) obesity. Results Class II and III patients were younger, more likely to be female, and more likely to have hypertension or diabetes than Class I patients. Preoperatively, Class III patients reported higher VAS Pain and lower Constant and ASES scores than Class I or II patients, and lower SAS scores than Class I patients. TSA led to significant improvement in all PROM across all Classes. At a mean follow-up of 53 months, there were no significant between-group differences in patient satisfaction rates or PROM except for a lower Constant score in Class III patients compared to Class I patients; however, this difference did not exceed the minimum clinically important difference. Conclusion In obese patients undergoing primary TSA, the severity of obesity does not have a clinically significant impact on postoperative PROM or patient satisfaction, arguing against the use of BMI cutoffs in TSA. With appropriate medical optimization, morbidly obese patients can achieve functional improvement and satisfaction levels comparable to those of their less obese counterparts.

BACKGROUND:Proximal humeral fractures (PHFs) are common in the elderly population, and the use of reverse total shoulder arthroplasty (rTSA) as treatment has risen substantially in recent years. As opposed to statistical significance, clinical value has increasingly been used to evaluate outcomes; thus, this study aims to define patient acceptable symptom state (PASS) thresholds, Minimal Clinically Important Difference (MCID), and substantial clinical benefit (SCB) values for American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, Constant-Murley score (CMS), and Shoulder Arthroplasty Smart (SAS) score in patients undergoing rTSA for PHFs. METHODS:A prospectively collected multicenter database inclusive of 43 clinical sites using Advita Ortho implant system was queried for patients who underwent rTSA for proximal humeral fracture with a minimum of 2 years' follow-up between 2007 and 2024. Patients were divided into Early (no prior open reduction and internal fixation [ORIF], malunion, or nonunion) and Late (history of ORIF, malunion, or nonunion) treatment groups. Prospectively, outcome metrics including preoperative and postoperative CMS, ASES score, SAS score, active range of motion, visual analog scale pain scores, self-reported shoulder function score, and patient satisfaction rate were collected from the electronic medical record. Receiver operating characteristic curve analysis was used to determine the PASS thresholds while MCID and SCB values were determined via anchor-based methods and distribution-based methods, respectively. RESULTS:PASS thresholds were numerically higher in the Late group across all measures. Postoperative ASES, CMS, and SAS scores all showed good discriminative ability for identifying patients who achieved PASS. Optimal PASS thresholds were 58 (area under the curve [AUC] = 0.73) and 60 (AUC = 0.80) for ASES, 62 (AUC = 0.65) and 66 (AUC = 0.77) for CMS, and 61 (AUC = 0.74) and 67 (AUC = 0.85) for SAS in the Early and Late groups, respectively. Anchor-based MCID values were slightly lower in the Late group, suggesting that a smaller score change was needed for perceived improvement by patients (ASES: 10.84 and 10.31; CMS: 9.59 and 8.54; SAS: 10.75 and 7.60). Distribution-based SCB thresholds were observed to have higher values in the Early group, indicating that patients treated earlier required greater functional improvement to perceive substantial benefit (ASES: 17.35 and 16.49; CMS: 15.35 and 13.67; SAS: 17.19 and 12.16). CONCLUSION:In patients undergoing rTSA for proximal humeral fracture, PASS thresholds for ASES, CMS, and SAS demonstrate good discriminative ability for identifying clinically meaningful improvement. Thresholds are reported separately for Early and Late treatment cohorts and should be interpreted as descriptive benchmarks.

BACKGROUND:Reverse total shoulder arthroplasty (rTSA) has become the procedure of choice for a failed anatomic total shoulder arthroplasty (aTSA). Little data exist regarding outcomes; the few studies published to date have small numbers, short follow-up, and most do not have a control group or use first-generation implants. The purpose of this study is to compare the clinical and radiographic outcomes of failed aTSA revised to rTSA to primary rTSA. METHODS:A prospective multicenter shoulder registry was used to conduct a retrospective review of patients who received a primary rTSA for osteoarthritis and rotator cuff disease and compare them to those who had an aTSA revised to a rTSA using the same implant between 2007 and 2021 with a minimum follow-up of 2 years. Cohorts were matched 3:1 (primary-to-revision) by age, gender, body mass index, and length of follow-up. Those who underwent revision for humeral fracture, infection, or an unknown reason were excluded. Preoperative and postoperative range of motion and patient-reported outcome measures (PROMs) were compared. Outcomes included rates of scapular notching, complications, revision, and patient satisfaction. RESULTS:There were 88 aTSAs revised to rTSAs compared with 264 matched primary rTSAs. In both cohorts, the mean age was 68 years, 59% were female, and the mean follow-up was 56 months. The most common reason for revision was rotator cuff tearing (53%), followed by aseptic glenoid loosening (34%), instability (9%), aseptic humeral loosening (6%), and glenoid component dissociation (3%). At latest follow-up, patients in both groups had statistically significant improvements in all outcome scores, exceeding the minimal clinically important difference (MCID) and the substantial clinical benefit (SCB). The revision cohort had significantly less postoperative abduction (P < .001) and forward elevation (P = .001) compared with the primary rTSA cohort. All PROMs in the revision cohort were significantly worse than those in the primary rTSA cohort. Patient satisfaction rate in the revision cohort was significantly lower than the primary cohort (P < .001). Complication (P = .005) and revision rates (P = .013) were significantly higher in the revision cohort, whereas scapular notching was similar. CONCLUSION:Patients undergoing revision of a failed aTSA to rTSA have worse clinical outcomes compared with those undergoing primary rTSA, including all PROMs, abduction, elevation, pain relief, and patient satisfaction, with higher complication and revision rates. Although patients in the revision group had significant improvements that exceeded the MCID and SCB, they do not achieve the same outcomes as patients who undergo primary rTSA.

Introduction: We developed a computed tomography (CT)-based tool designed for automated segmentation of deltoid muscles, enabling quantification of radiomic features and muscle fatty infiltration. Prior to use in a clinical setting, this machine learning (ML)-based segmentation algorithm requires rigorous validation. The aim of this study is to conduct shoulder expert validation of a novel deltoid ML auto-segmentation and quantification tool. Materials and Methods: A SwinUnetR-based ML model trained on labeled CT scans is validated by three expert shoulder surgeons for 32 unique patients. The validation evaluates the quality of the auto-segmented deltoid images. Specifically, each of the three surgeons reviewed the auto-segmented masks relative to CT images, rated masks for clinical acceptance, and performed a correction on the ML-generated deltoid mask if the ML mask did not completely contain the full deltoid muscle, or if the ML mask included any tissue other than the deltoid. Non-inferiority of the ML model was assessed by comparing ML-generated to surgeon-corrected deltoid masks versus the inter-surgeon variation in metrics, such as volume and fatty infiltration. Results: The results of our expert shoulder surgeon validation demonstrates that 97% of ML-generated deltoid masks were clinically acceptable. Only two of the ML-generated deltoid masks required major corrections and only one was deemed clinically unacceptable. These corrections had little impact on the deltoid measurements, as the median error in the volume and fatty infiltration measurements was <1% between the ML-generated deltoid masks and the surgeon-corrected deltoid masks. The non-inferiority analysis demonstrates no significant difference between the ML-generated to surgeon-corrected masks relative to inter-surgeon variations. Conclusions: Shoulder expert validation of this CT image analysis tool demonstrates clinically acceptable performance for deltoid auto-segmentation, with no significant differences observed between deltoid image-based measurements derived from the ML generated masks and those corrected by surgeons. These findings suggest that this CT image analysis tool has potential to reliably quantify deltoid muscle size, shape, and quality. Incorporating these CT image-based measurements into the pre-operative planning process may facilitate more personalized treatment decision making, and help orthopedic surgeons make more evidence-based clinical decisions.

Background/Hypothesis: Reverse total shoulder arthroplasty (rTSA) has become the operative treatment of choice for acute proximal humerus fractures in the elderly population, but little data exist on the long-term outcomes or how they compare to rTSA done for degenerative conditions. The purpose of this study is to compare the clinical and radiographic outcomes of patients undergoing rTSA for acute fracture versus degenerative conditions with a minimum 5-year follow-up. Methods: Data was extracted from an international registry of patients with the Exactech Equinoxe rTSA implant from 2007 to 2018. Patients with a minimum follow-up of 5 years were then split into fracture and degenerative cohorts and matched 1:3 based on age, sex, and follow-up duration. Clinical and radiographic outcomes were compared between the cohorts including range of motion, patient-reported outcome measures, visual analouge scale pain score, complication and revision rates, implant characteristics, and scapular notching. This data was analyzed using Welch's t-test, Fisher's exact test, or Wilcoxon rank sum test. Results: There were 384 total patients included in the study, with 96 fractures and 288 degenerative. At a mean follow-up of 6.4 years, the degenerative cohort had significant improvements in all patient-reported outcome measures and range of motion, compared to their preoperative status. At the latest follow-up, the mean American Shoulder and Elbow Surgeons score was 83 and the mean visual analouge scale pain score was 1.1 for both cohorts. Patients with degenerative indications had greater forward elevation which did not meet the minimally clinically important difference and greater internal rotation which did not meet the substantial clinical benefit threshold. Patient satisfaction was very high for both cohorts, with 97% in the degenerative cohort and 91% in the fracture cohort satisfied with the procedure (P = .276). Complication and revision rates were similar between the 2 cohorts. Patients in the fracture cohort had a larger glenosphere diameter (P = .045) and greater combined liner/tray offset (P = .05). Patients in the elective cohort more frequently required an augmented baseplate (P < .001). Scapular notching was 11% in the degenerative cohort and 9% in the fracture cohort (P = .82). Conclusion: This study demonstrates no significant differences in the clinical or radiographic outcomes at a minimum of 5 years follow-up for patients undergoing rTSA for acute fracture versus degenerative conditions. Patients undergoing rTSA for either indication have similar rates of complications, revisions, and scapular notching, with high patient satisfaction. Patients undergoing rTSA for an acute fracture can expect similar results to those undergoing rTSA for degenerative conditions at minimum 5-year follow-up. Level of evidence: Level III; Retrospective Cohort Comparison; Prognosis Study (c) 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

BACKGROUND:There has been a trend toward the use of shorter humeral components with the goal of preserving bone, decreasing operative time, and a theoretical decrease in stress shielding. The purpose of this study was to compare the clinical and functional outcomes of anatomic total shoulder arthroplasty among standard-length stem, short-stem, and stemless humeral components, with a minimum of 2-year follow-up. METHODS:A retrospective review of a multicenter international database was performed for anatomic total shoulder arthroplasty with a minimum of 2-year follow-up between 2018 and 2021 using Standard Equinoxe stems, Equinoxe Preserve (Short) stems, or Equinoxe Stemless components (Exactech, Inc., Gainesville, FL, USA). Outcome measures included range of motion and patient-reported outcome measures (PROMs). Postoperative radiographic findings including the presence of glenoid and humeral radiolucent lines in zones specific to the stem design were evaluated. Complication and revision rates were recorded. RESULTS:A total of 825 patients were included (164 standard-length stem, 356 short-stem, and 305 stemless). The mean follow-up was 37.9 ± 12.6 months. There was no significant difference in previous shoulder surgeries or medical comorbidities among the groups. The mean final forward elevation for standard-length stem, short-stem, and stemless components was 156°, 158°, and 156°, respectively (P = .636). Final external rotation for standard-length stem, short-stem, and stemless components was 58°, 57°, and 51°, respectively (P < .001). Final internal rotation scores were similar across groups (P = .090). Final PROMs did not meet the minimal clinically important difference across cohorts. The mean operative time for the standard-length stem group was 101.8 minutes, for the short-stem group 92.7 minutes, and for the stemless group 89.2 minutes (P < .001). There was no statistically significant difference in complication rate or revision rate. The rate of humeral component radiolucent lines was greater for standard-length stems (P < .001) with a rate of 11.9% for standard-length stem, 1.7% for short-stem, and 1.6% for stemless components. Patient satisfaction was also similar among the 3 cohorts (P = .757). CONCLUSIONS:Our findings demonstrate similar postoperative motion and PROM scores irrespective of the humeral stem component used. Complication and revision rates were similar for all 3 cohorts. Radiolucent lines were lowest with the stemless component. Early data support the use of stemless and short-stem humeral components that may be advantageous in decreasing operative time and preserving humeral bone for potential revision. Longer term studies are needed to confirm the survivability and durability of these shorter components.

Background: When missing data are present in clinical outcomes studies, complete-case analysis (CCA) is often performed, whereby patients with missing data are excluded. While simple, CCA analysis may impart selection bias and reduce statistical power, leading to erroneous statistical results in some cases. However, there exist more rigorous statistical approaches, such as single and multiple imputation, which approximate the associations that would have been present in a full dataset and preserve the study's power. The purpose of this study is to evaluate how statistical results differ when performed after CCA analysis versus imputation methods. Methods: This simulation study analyzed a sample dataset consisting of 2204 shoulders, with complete datapoints from a larger multicenter total shoulder arthroplasty database. From the sampled dataset of demographics, surgical characteristics, and clinical outcomes, we created five test datasets, ranging from 100 to 2000 shoulders, and simulated 10-50% missingness in the postoperative American Shoulder and Elbow Surgeons (ASES) score and range of motion in four planes in missing completely at random (MCAR), missing at random (MAR), and not missing at random (NMAR) patterns. Missingness in outcomes was remedied using CCA, three single imputation techniques, and two multiple imputation techniques. The imputation performance was evaluated relative to the native complete dataset using the root mean squared error (RMSE) and the mean absolute percentage error (MAPE). We also compared the mean and standard deviation (SD) of the postoperative ASES score and the results of multivariable linear and logistic regression to understand the effects of imputation on the study results. Results: The average overall RMSE and MAPE were similar for MCAR (22.6 and 27.2%) and MAR (19.2 and 17.7%) missingness patterns, but were substantially poorer for NMAR (37.5 and 79.2%); the sample size and the percentage of data missingness minimally affected RMSE and MAPE. Aggregated mean postoperative ASES scores were within 5% of the true value when missing data were remedied with CCA, and all candidate imputation methods for nearly all ranges of sample size and data missingness when data were MCAR or MAR, but not when data were NMAR. When data were MAR, CCA resulted in overestimates of the SD. When data were MCAR or MAR, the accuracy of the regression estimate (β or OR) and its corresponding 95% CI varied substantially based on the sample size and proportion of missing data for multivariable linear regression, but not logistic regression. When data were MAR, the width of the 95% CI was up to 300% larger when CCA was used, whereas most imputation methods maintained the width of the 95% CI within 50% of the true value. Single imputation with k-nearest neighbor (kNN) method and multiple imputation with predictive mean matching (MICE-PMM) best-reproduced point estimates and intervariable relationships resembling the native dataset. Availability of correlated outcome scores improved the RMSE, MAPE, accuracy of the mean postoperative ASES score, and multivariable linear regression model estimates. Conclusions: Complete-case analysis can introduce selection bias when data are MAR, and it results in loss of statistical power, resulting in loss of precision (i.e., expansion of the 95% CI) and predisposition to false-negative findings. Our data demonstrate that imputation can reliably reproduce missing clinical data and generate accurate population estimates that closely resemble results derived from native primary shoulder arthroplasty datasets (i.e., prior to simulated data missingness). Further study of the use of imputation in clinical database research is critical, as the use of CCA may lead to different conclusions in comparison to more rigorous imputation approaches.

Background: The purpose of this study was to compare the outcomes of primary reverse total shoulder arthroplasty (rTSA) using constrained liners (in a 145 degrees onlay implant, Equinoxe [Exactech]) with primary rTSA using standard liners with a minimum 1-year follow-up. Methods: A total of 836 primary rTSA patients were analyzed in this study. Patients treated with constrained liners (n = 209) were cross-matched 1:3 for age, gender, glenosphere diameter, and follow-up duration and compared with 627 patients who underwent primary rTSA with standard liners. Study endpoint was at 1 year. Outcomes were analyzed preoperatively and at the latest follow-up. Patient characteristics, postoperative range of motion (ROM), patient-reported outcomes (PROs), complications and revisions were recorded. Results: There was no statistically significant changes in improvement in pain (-4.9 vs. -5.1; P = .356), ROM (abduction, 45.7 degrees vs. 47.9 degrees, P = .522; forward elevation, 44.0 degrees vs. 50.8 degrees, P = .057; internal rotation score 1.0 vs. 1.1, P = .709; and external rotation, 17.9 degrees vs. 16.7 degrees, P = .543), or PROs (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES] score, 44.5 vs. 43.7, P = .107; and Shoulder Arthroplasty Smart [SAS] score, 27.5 vs. 30.0, P = .052) between the constrained and standard liner cohorts at minimum 1-year follow-up. However, the constrained liner rTSA cohort had a significantly higher rate of adverse events (6.2% vs. 2.7%, P = .012), including a higher rate of scapular notching (15.6% vs. 8.8%, P = .015). Conclusion: The use of constrained liners in primary rTSA demonstrated no significant difference in the change in pain, abduction, forward elevation, external and internal rotation scores, ASES scores, and SAS scores at minimum 1-year follow-up. There was no significant difference in forward elevation or abduction compared with standard liners. However, we observed that the overall rate of adverse events, including scapular notching, were significantly higher in the constrained liner cohort. Long-term clinical and radiographic follow-up is necessary to fully elucidate the durability of these results. At this time, it is unclear if constrained liners have any benefit in rTSA. Level of evidence: Level III; Retrospective Cohort Comparison using Large Database; Treatment Study (c) 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

BACKGROUND:Given the high variability in patient presentation, notable challenges exist in determining patient candidacy for anatomic total shoulder arthroplasty (aTSA). The purpose of this study was to use a modified version of prior scenario-based appropriateness use criteria to evaluate the prevalence of inappropriate, appropriate, and inconclusive aTSA. METHODS:Patients undergoing primary aTSA were evaluated for preoperative outcome scores and baseline demographic information from a multicenter database. Using a validated appropriateness use criteria algorithm, these patients were grouped "inappropriate," "inconclusive," or "appropriate." RESULTS:Seven hundred seventy-four patients who underwent aTSA were included. "Appropriate" patients comprised 23.9% of the cohort, while 17.8% were "inappropriate," and 58.3% were "inconclusive." Compared with the inconclusive and inappropriate groups, the "appropriate" patients were found to have markedly worse preoperative pain and functional outcomes scores. No notable difference was observed between the number of patients who received intra-articular injections, number of injections received, and analgesic use across the groups. CONCLUSIONS:The large proportion of "inconclusive" patients suggests a lack of consensus regarding aTSA versus reverse TSA candidacy and may be secondary to factors such as worse glenoid morphology and/or prior rotator cuff repair, which are subjects of current debate in determining appropriateness for reverse TSA versus aTSA. Although no definitive conclusions can be made regarding if this algorithm ultimately improves patient outcomes, this study seeks to only help streamline patient evaluation based on American Shoulder and Elbow Surgeons high-volume surgeons' opinion and highlight the large variation in the indications for aTSA in real-world surgical cases.

Background The purpose of this study is to retrospectively analyze all primary anatomic total shoulder arthroplasty (aTSA) patients within a multi-center international database of a single prosthesis to identify risk factors for patients with rotator cuff tear (RCT) and aseptic glenoid loosening. Methods To investigate the risk factors for RCT and aseptic glenoid loosening, we retrospectively analyzed all aTSA patients with 2-year minimum follow-up from a multi-center international database of a single platform shoulder system, only excluding patients with a history of revision arthroplasty, infections, and humeral fractures. A univariate/multivariate analysis was conducted to compare primary aTSA patients who had report of: 1) a RCT and/or subscapularis failure and 2) aseptic glenoid loosening/cage glenoid dissociations, to identify the differences in (i) intrinsic patient demographics and comorbidities and (ii) implant and operative parameters. Finally, to adapt our statistical analysis for prospective identification of patients most at-risk for RCT and aseptic glenoid loosening, we stratified the dataset by multiple risk factor combinations and calculated the odds ratio to determine the impact of accumulating risk factors on the incidence rate of each complication. Results 122 aTSA shoulders had a RCT for a rate of 3.2% and 123 aTSA shoulders had aseptic glenoid loosening for a rate of 3.3%. The multivariate analysis identified that aTSA patients with RCT were more likely to have previous shoulder surgery (p<0.001) and small size glenoids (p=0.002). Additionally, the multivariate analysis identified that aTSA patients with aseptic glenoid loosening were more likely to be younger (≤62 years at the time of surgery, p=0.001), have small size glenoids (p=0.033) and have a non-hybrid glenoids (p<0.001). Stratifying patients with multiple risk factors identified multiple aTSA cohorts with odds ratios >2 for RCT or aseptic glenoid loosening. Discussion This analysis of 2,699 primary aTSA identified risk factors for the two most common postoperative complications: RCTs and aseptic glenoid loosening. Using these risk factors, we calculated odds ratios for patient cohorts with multiple risk factors to identify the patients with the greatest risk for each complication. This information is useful to guide the surgeon in their preoperative counseling and potentially mitigate the occurrence of these complications, by indicating patients with these risk-factors for alternative treatment strategies, like rTSA, instead of aTSA.

Background: Machine learning (ML)-based clinical decision support tools (CDSTs) make personalized predictions for different treatments; by comparing predictions of multiple treatments, these tools can be used to optimize decision making for a particular patient. However, CDST prediction accuracy varies for different patients and also for different treatment options. If these differences are sufficiently large and consistent for a particular subcohort of patients, then that bias may result in those patients not receiving a particular treatment. Such level of bias would deem the CDST "unfair." The purpose of this study is to evaluate the "fairness" of ML CDST-based clinical outcomes predictions after anatomic (aTSA) and reverse total shoulder arthroplasty (rTSA) for patients of different demographic attributes. Methods: Clinical data from 8280 shoulder arthroplasty patients with 19,249 postoperative visits was used to evaluate the prediction fairness and accuracy associated with the following patient demographic attributes: ethnicity, sex, and age at the time of surgery. Performance of clinical outcome and range of motion regression predictions were quantified by the mean absolute error (MAE) and performance of minimal clinically important difference (MCID) and substantial clinical benefit classification predictions were quantified by accuracy, sensitivity, and the F1 score. Fairness of classification predictions leveraged the "four-fifths" legal guideline from the US Equal Employment Opportunity Commission and fairness of regression predictions leveraged established MCID thresholds associated with each outcome measure. Results: For both aTSA and rTSA clinical outcome predictions, only minor differences in MAE were observed between patients of different ethnicity, sex, and age. Evaluation of prediction fairness demonstrated that 0 of 486 MCID (0%) and only 3 of 486 substantial clinical benefit (0.6%) classification predictions were outside the 20% fairness boundary and only 14 of 972 (1.4%) regression predictions were outside of the MCID fairness boundary. Hispanic and Black patients were more likely to have ML predictions out of fairness tolerance for aTSA and rTSA. Additionally, patients < 60 years old were more likely to have ML predictions out of fairness tolerance for rTSA. No disparate predictions were identified for sex and no disparate regression predictions were observed for forward elevation, internal rotation score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score, or global shoulder function. Conclusion: The ML algorithms analyzed in this study accurately predict clinical outcomes after aTSA and rTSA for patients of different ethnicity, sex, and age, where only 1.4% of regression predictions and only 0.3% of classification predictions were out of fairness tolerance using the proposed fairness evaluation method and acceptance criteria. Future work is required to externally validate these ML algorithms to ensure they are equally accurate for all legally protected patient groups. Level of evidence: Basic Science Study; Validation of Computer Modeling (c) 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

BackgroundAlthough the Favard classification is commonly utilized by surgeons to describe the supero-inferior morphology of the glenoid when treating rotator cuff arthropathy (RCA), its utility in prognosticating patients’ clinical state before and after reverse shoulder arthroplasty (RSA) remains unproven. We assessed the prognostic value of the Favard glenoid classification on preoperative clinical state and postoperative clinical and radiographic outcomes in RSA.MethodsA prospectively-collected, multi-center database for a single-platform shoulder arthroplasty system was queried for patients with RCA who underwent RSA with minimum 2-year clinical follow-up. Differences in patient-reported outcome scores (PROMs) [SST, ASES, SPADI, VAS Pain, Shoulder Function score], combined patient-reported and clinical-input scores (Constant, UCLA, SAS), active range of motion (ROM) values (forward elevation [FE], abduction, external rotation [ER], internal rotation [IR], radiographic outcomes (humeral radiolucency line rates, scapular notching rate), and the incidence of postoperative complications and revision surgery were compared by glenoid deformity type per the Favard classification. Comparisons were performed to assess the ability of the Favard classification to prognosticate the preoperative, postoperative, and improved state after RSA.Results400 RSAs performed for RCA were included. Comparison of outcomes between Favard glenoid types resulted in 6 pairwise comparisons of 12 clinical outcome metrics, yielding 72 total Favard glenoid pairwise comparisons for each clinical state (preoperative, postoperative, improvement). Of the 216 possible pairwise Favard glenoid type / metric comparisons, statistical significance was only reached for 3% of the combinations (7/216). Among E0, E1, and E2 glenoids, the only statistically significant pairwise comparison identified amongst all three clinical states was a more favorable preoperative ASES score for E0 versus E2 glenoids. Preoperatively, E3 glenoids had poorer ER, IR, and SAS scores compared to E0 glenoids and poorer ER compared to E2 glenoids. Postoperatively, E3 glenoids had a poorer IR score compared to E0 glenoids and poorer ER compared to E1 glenoids. No pairwise differences in pre- to postoperative improvement were found. There were no statistically significant pairwise differences in humeral lucency rate, scapular notching rate, complication rates, or revision rates between Favard glenoid types.ConclusionAlthough useful for describing degenerative changes to the glenohumeral joint, the Favard classification offers little prognostic information regarding patient outcomes before and after RSA aside from poorer pre- and postoperative axial rotation in E3 glenoids. Alternative glenoid classification systems or predictive models should be considered for more precise prognoses of patients undergoing RSA for RCA.

Background: Clinical significance, as opposed to statistical significance, has increasingly been utilized to evaluate outcomes after total shoulder arthroplasty (TSA). The purpose of this study was to identify thresholds of the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for TSA outcome metrics and determine if these thresholds are influenced by prosthesis type (anatomic or reverse TSA), sex, or preoperative diagnosis. Methods: A prospectively collected international multicenter database inclusive of 38 surgeons was queried for patients receiving a primary aTSA or rTSA between 2003 and 2021. Prospectively, outcome metrics including ASES, shoulder function score (SFS), SST, UCLA, Constant, VAS Pain, shoulder arthroplasty smart (SAS) score, forward flexion, abduction, external rotation, and internal rotation was recorded preoperatively and at each follow-up. A patient satisfaction question was administered at each follow-up. Anchor-based MCID, SCB, and PASS were calculated as defined previously overall and according to implant type, preoperative diagnosis, and sex. The percentage of patients achieving thresholds was also quantified. Results: A total of 5851 total shoulder arthroplasties (TSAs) including aTSA (n = 2236) and rTSA (n = 3615) were included in the study cohort. The following were identified as MCID thresholds for the overall (aTSA thorn rTSA irrespective of diagnosis or sex) cohort: VAS Pain (-1.5), SFS (1.2), SST (2.1), Constant (7.2), ASES (13.9), UCLA (8.2), SPADI (-21.5), and SAS (7.3), Abduction (13 degrees), Forward elevation (16 degrees), External rotation (4 degrees), Internal rotation score (0.2). SCB thresholds for the overall cohort were: VAS Pain (-3.3), SFS (2.9), SST 3.8), Constant (18.9), ASES (33.1), UCLA (12.3), SPADI (-44.7), and SAS (18.2), Abduction (30 degrees), Forward elevation (31 degrees), External rotation (12 degrees), Internal rotation score (0.9). PASS thresholds for the overall cohort were: VAS Pain (0.8), SFS (7.3), SST (9.2), Constant (64.2), ASES (79.5), UCLA (29.5), SPADI (24.7), and SAS (72.5), Abduction (104 degrees), Forward elevation (130 degrees), External rotation (30 degrees), Internal rotation score (3.2). MCID, SCB, and PASS thresholds varied depending on preoperative diagnosis and sex. Conclusion: MCID, SCB, and PASS thresholds vary depending on implant type, preoperative diagnosis, and sex. A comprehensive understanding of these differences as well as identification of clinically relevant thresholds for legacy and novel metrics is essential to assist surgeons in evaluating their patient's outcomes, interpreting the literature, and counseling their patients preoperatively regarding expectations for improvement. Given that PASS thresholds are fragile and vary greatly depending on cohort variability, caution should be exercised in conflating them across different studies. (c) 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

BackgroundWhile surgeons attempt to correct the baseplate version of a reverse total shoulder arthroplasty (rTSA), clinical outcomes based on the planned final version remain unknown. The purpose of this study is to determine the clinical and radiographic outcomes of rTSA based on the planned final version the baseplate. Our hypothesis is that increasing component retroversion will not affect outcomes.MethodsAll primary rTSA patients in an IRB approved multicentered international registry with a 2-year minimum follow-up implanted with computer navigation so the final planned baseplate version is known were included, except fracture and revision indications. A single medialized glenoid/lateralized humerus rTSA implant system was used with a standard or augmented baseplate. Patients were stratified by final baseplate version into two cohorts: 0-5° (Group 1) or 6-15° (Group 2) of retroversion. Demographics, radiographic outcomes, range of motion, and patient reported outcome scores were compared between groups using Welch’s t-test and Fisher’s Exact test.ResultsFive hundred and thirty-five patients (307 females/226 males/2 unknown) were identified, with a mean follow-up of 30 months. Demographics were similar between the cohorts. The mean native and final retroversion was 9.0° and 1.5° in Group 1 and 16.3° and 8.6° in Group 2, respectively. Preoperatively, 72% of patients were 6-15° retroverted. Postoperatively, 73% of patients were 0-5° retroverted, and 27% were 6-15°, with 97% of patients having less than or equal to 10° of planned baseplate retroversion. There were no clinically significant differences between the cohorts with regards to postoperative pain, range of motion or patient reported outcome scores, except for abduction and IR greater in the 6-15° cohort, which did not exceed the substantial clinical benefit. Scapular notching was low (7% vs 8%) and less than reported without computer navigation. Complication and revision rates were similar between the two groups. Patient satisfaction was high (much better/better, 94% versus 95%) and not significantly different between the two groups.DiscussionThere were no significant clinical differences between cohorts. This study demonstrates that favorable outcomes are achieved with a planned final baseplate version of less than 15° retroversion, with few differences between 0-5° and 6-15°. rTSA is forgiving enough such that one may plan to correct preoperative retroversion to less than 15° postoperatively in lieu of targeting postoperative version between 0°-5° for patients with higher native retroversion, potentially requiring less eccentric reaming especially when combined with other corrective measures.

INTRODUCTION Reverse total shoulder arthroplasty (rTSA) has become the operative treatment of choice for acute proximal humerus fractures in the elderly population, but little data exists on the long-term outcomes or how they compare to rTSA done for degenerative conditions. The purpose of this study is to compare the clinical and radiographic outcomes of patients undergoing rTSA for acute fracture versus degenerative conditions with a minimum 5-year follow-up. METHODS Data was extracted from an international registry of patients with the Exactech Equinoxe rTSA implant from 2007-2018. Patients with a minimum follow-up of 5 years were then split into fracture and degenerative cohorts and matched 1:3 based on age, sex, and follow-up duration. Clinical and radiographic outcomes were compared between the cohorts including range of motion (ROM), patient-reported outcome measures (PROM), VAS pain score, complication and revision rates, implant characteristics, and scapular notching. This data was analyzed using Welch’s t-test, Fisher’s exact test, or Wilcoxon rank sum test. RESULTS There were 384 total patients included in the study, with 96 fractures and 288 degenerative. At a mean follow-up of 6.4 years, the degenerative cohort had significant improvements in all PROMs and ROM, compared to their preoperative status. At the latest follow-up, the mean ASES score was 83 and the mean VAS pain score was 1.1 for both cohorts. Patients with degenerative indications had greater forward elevation which did not meet the minimally clinically important difference and greater internal rotation which did not meet the substantial clinical benefit threshold. Patient satisfaction was very high for both cohorts, with 97% in the degenerative cohort and 91% in the fracture cohort satisfied with the procedure (p=0.276). Complication and revision rates were similar between the two cohorts. Patients in the fracture cohort had a larger glenosphere diameter (p=0.045) and greater combined liner/tray offset (p=0.05). Patients in the elective cohort more frequently required an augmented baseplate (p<0.001). Scapular notching was 11% in the degenerative cohort and 9% in the fracture cohort (p=0.82). DISCUSSION This study demonstrates no significant differences in the clinical or radiographic outcomes at a minimum of 5 years follow-up for patients undergoing rTSA for acute fracture versus degenerative conditions. Patients undergoing rTSA for either indication have similar rates of complications, revisions, and scapular notching, with high patient satisfaction. Patients undergoing rTSA for an acute fracture can expect similar results to those undergoing rTSA for degenerative conditions at minimum 5-year follow-up.

Background:Newer generation humeral stem designs in total shoulder arthroplasty (TSA) are trending towards shorter lengths and uncemented fixation. The goal of this study is to report a 2-yr minimum clinical and radiographic outcomes of an uncemented short-stem press-fit humeral stem in anatomic total shoulder arthroplasty (ATSA) and reverse total shoulder arthroplasty (RTSA).Methods:A retrospective multicenter database review was performed of all patients who received an uncemented short-length press-fit humeral stem (Equinoxe Preserve humeral stem, Exactech, Inc., Gainesville, FL, USA) in ATSA and RTSA with a minimum two-year follow-up. The primary outcome was the prevalence of humeral stems at risk of radiographic loosening. Secondary outcomes included evaluation of functional outcome scores and prevalence of revision TSA for humeral stem loosening. Two blinded observers performed radiographic analyses, which included humeral stem alignment, canal filling ratio, radiolucent lines, stress shielding (calcar and greater tuberosity), and changes in component position (subsidence and stem shift). At risk stems were defined by the presence of one or more of the following: humeral stem with shifting or subsidence, scalloping of the humeral cortex, or radiolucent lines measuring 2 mm or greater in 3 or more zones.Results:287 patients (97 ATSA and 190 RTSA) were included in this study. The mean follow-up was 35.9 (±6.1) months. There were significant improvements for all functional outcome scores (P < .05), range of motion (P < .05), and visual analogue pain scale pain (P < .05). The prevalence of humeral stem at risk of radiographic loosening was 1% in the ATSA group (1/97) and 18.4% in the RTSA group (35/190). Calcar resorption was seen in 34% of ATSA and 19% of RTSA, with severe resorption in 12.4% of ATSA and only 3.2% of RTSA. Greater tuberosity resorption was present in 3.1% of ATSA and 7.9% of RTSA. The mean canal filling ratio was 50.2% (standard deviation 11.2%). Using logistic regression, a significant positive correlation between canal filling ratio and stress shielding (P < .01) was seen for both calcar and tuberosity stress shielding. The revision surgery rate was 0% in ATSA compared to 1.6% in RTSA.Conclusion:This retrospective study demonstrates a low revision rate and low prevalence of humeral stems at risk of radiographic loosening at two years with a press-fit short-stem humeral design in ATSA. Physiologic subsidence of humeral stems can account for higher prevalence of humeral stems at radiographic risk of loosening in RTSA compared to ATSA.

Background: Superior augment use may help avoid superior tilt while minimizing removal of inferior glenoid bone. Therefore, our goal was to compare superior augments vs. no-augment baseplates in reverse shoulder arthroplasty (RSA) for patients with rotator cuff dysfunction and no significant superior glenoid erosion. Methods: A multicenter retrospective analysis of 145 patients who underwent RSA with intraoperative navigation (Equinoxe GPS; Exactech) and 3-year follow-up (mean 32 months' follow-up, range 20-61 months) who had preoperative superior inclination less than 10 degrees and retroversion less than 15 degrees. Patient demographics, radiographic measurements, surgical characteristics, patient-reported outcomes at preoperative and postoperative visit closest to 3 years, and adverse events at final follow-up were obtained. Operative time, planned inclination, and planned version of the baseplate were obtained. chi(2) test was used to compare categorical variables, and Student t test was used to compare the augment and no-augment cohorts. Results: The study population consisted of 54 superior augment patients and 91 no-augment patients. The augment cohort had lower body mass index (27.2 vs. 29.4, P = .023) and higher native superior inclination (5.9 degrees vs. 1.4 degrees, P < .001). No difference between the augment and no-augment cohorts was found regarding age (P = .643), gender (P = .314), medical comorbidities (P > .05), surgical indication (P = .082), and native glenoid version (P = .564). The augment cohort had higher internal rotation score (4.6 vs. 3.9, P = .023), and all remaining range of motion (ROM) and patient-reported outcomes (PROs) preoperatively were not significantly different. At final follow-up, active ROM in all planes was not different between the cohorts. Regarding PROs, the postoperative Shoulder Arthroplasty Smart score was significantly higher (78.0 vs. 73.6, P = .042), and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score trended toward higher (83.6 vs. 77.5, P = .063) in the augment cohort. The augment cohort had a significantly lower proportion of patients who planned to have superior baseplate tilt (1.9% vs. 14.3%, P = .012) and had greater mean inclination correction (6.3 degrees vs. 1.3 degrees, P < .001), compared with the no-augment cohort. Adverse events were rare, and there was no significant difference found between the augment and no-augment cohorts (5.6% vs. 3.3%, P = .509). Discussion: Superior augmented baseplate in RSA with minimal superior glenoid erosion is associated with similar ROM and adverse events with somewhat improved postoperative PROs compared with nonaugmented baseplates at the 3-year follow-up. Additionally, superior augments resulted in a greater proportion of baseplates planned to avoid superior tilt, and trended toward shorter operative times. Further investigation of long-term glenoid baseplate loosening is imperative to fully understand the cost-effectiveness of superior augments in the setting of minimal glenoid deformity.

Background: Despite the importance of the deltoid to shoulder biomechanics, very few studies have quantified the three-dimensional shape, size, or quality of the deltoid muscle, and no studies have correlated these measurements to clinical outcomes after anatomic (aTSA) and/or reverse (rTSA) total shoulder arthroplasty in any statistically/scientifically relevant manner. Methods: Preoperative computer tomography (CT) images from 1057 patients (585 female, 469 male; 799 primary rTSA and 258 primary aTSA) of a single platform shoulder arthroplasty prosthesis (Equinoxe; Exactech, Inc., Gainesville, FL) were analyzed in this study. A machine learning (ML) framework was used to segment the deltoid muscle for 1057 patients and quantify 15 different muscle characteristics, including volumetric (size, shape, etc.) and intensity-based Hounsfield (HU) measurements. These deltoid measurements were correlated to postoperative clinical outcomes and utilized as inputs to train/test ML algorithms used to predict postoperative outcomes at multiple postoperative timepoints (1 year, 2–3 years, and 3–5 years) for aTSA and rTSA. Results: Numerous deltoid muscle measurements were demonstrated to significantly vary with age, gender, prosthesis type, and CT image kernel; notably, normalized deltoid volume and deltoid fatty infiltration were demonstrated to be relevant to preoperative and postoperative clinical outcomes after aTSA and rTSA. Incorporating deltoid image data into the ML models improved clinical outcome prediction accuracy relative to ML algorithms without image data, particularly for the prediction of abduction and forward elevation after aTSA and rTSA. Analyzing ML feature importance facilitated rank-ordering of the deltoid image measurements relevant to aTSA and rTSA clinical outcomes. Specifically, we identified that deltoid shape flatness, normalized deltoid volume, deltoid voxel skewness, and deltoid shape sphericity were the most predictive image-based features used to predict clinical outcomes after aTSA and rTSA. Many of these deltoid measurements were found to be more predictive of aTSA and rTSA postoperative outcomes than patient demographic data, comorbidity data, and diagnosis data. Conclusions: While future work is required to further refine the ML models, which include additional shoulder muscles, like the rotator cuff, our results show promise that the developed ML framework can be used to evolve traditional CT-based preoperative planning software into an evidence-based ML clinical decision support tool.

Introduction Optimal biomechanics in reverse total shoulder arthroplasty (rTSA) are still a topic of debate. Although larger glenospheres have been linked with a theoretical improvement in the range of movement, results from clinical studies are mixed. We hypothesised that matching glenosphere diameter to patient height would result in greater improvements in post-operative range of motion (ROM) and patient-reported outcomes (PROMs). Methods An international database of rTSAs was analysed. After exclusions, 3318 rTSA patients were classified as short (<158 cm), average (158–173 cm) or tall(>173 cm). Outcomes were stratified for glenosphere size (small≤38 mm, large≥40 mm). Results were compared preoperatively and at 2 years. Results In short patients glenosphere diameter had no statistically significant impact on the degree of post-operative improvement for any ROM or PROM. Average height patients treated with small glenospheres had significantly more improvement in internal rotation (1.3 vs 1.0, p = 0.01), VAS pain (5.3 vs 4.8, p = 0.002), American Shoulder and Elbow Surgeons (47.8 vs 45.2, p = 0.03) and Shoulder Arthroplasty Smart (30.9 vs 28.2, p = 0.01) but significantly less improvement in constant score (31.7 vs 35.3, p = 0.009). Tall patients treated with small glenospheres had significantly more improvement in external rotation (21.2 vs 16.4, p = 0.01) and VAS pain scores (4.7 vs 4.3, p = 0.04). Conclusions While most significant differences favoured small glenospheres, the magnitude of these differences was small. Overall, patients of all heights can expect similar clinical improvements irrespective of glenosphere size.