Quantifying bone loss and lateralization with standardized baseplate versus augmented baseplates.

Background: Reverse shoulder arthroplasty continues to be utilized for the treatment of cuff tear arthropathy, glenohumeral degenerative joint disease, and irreparable rotator cuff tears. With advancement in component designs, glenoid retroversion and inclination are now correctable with augmented baseplates. However, quantifying bone loss and lateralization compared to standard baseplates has not been studied. The purpose of the current study is to determine the volume of bone reamed and net lateralization with a standardized baseplate vs. augmented baseplate when glenoid inclination was corrected to neutral. Methods: A series of 21 computed tomography scans of patients presenting for shoulder arthroplasty were chosen based on a range of increasing native positive inclination. Computed tomography scans were uploaded into segmentation software and processed. Four fellowship trained shoulder surgeons were then blinded from each other and virtually placed a neutral baseplate and an augmented baseplate for each specimen. Baseplate position was standardized. Additionally, baseplate backside seating of a minimum of 80% was also standardized and glenosphere (nonlateralized) size was selected to eliminate variation in baseplate contact and position. Glenoid inclination was corrected to a minimal of neutral in each specimen as well as glenoid retroversion corrected to <10°. Net lateralization from the center of the glenoid to the most lateral aspect of the baseplate was calculated in millimeters. Results: The mean glenoid retroversion was 8.1° and superior inclination was 10.6° for all specimens. Across all specimens and surgeons, use of a 10-degree augment resulted in similar baseplate backside seating area (219.2 mm3 vs. 226.2 mm3, P > .05). There was substantially lower volume of bone reamed in the augmented baseplate patients (619 mm3 vs. 1102 mm3, P < .001). Larger standard deviation seen in the augmented baseplate columns are attributed to differences in surgeon preference for percent backside seating, which was standardized at a minimum of 80%. Use of a 10-degree full wedge augment resulted in 2.4 mm additional glenoid lateralization than a neutral baseplate on average across all included scapulae. Conclusion: The current study demonstrates approximately 50% less bone removal and 2.4 mm of true lateralization with a 10-degree augmented baseplate when compared to standard baseplates.

Machine Learning Models Can Define Clinically Relevant Bone Density Subgroups based on Patient Specific Calibrated CT Scans in Patients Undergoing Reverse Shoulder Arthroplasty.

BACKGROUND: Reduced bone density is recognized as a predictor for potential complications in reverse shoulder arthroplasty (RSA). While humeral and glenoid planning based on preoperative computed tomography (CT) scans assist in implant selection and position, reproducible methods for quantifying the patients' bone density are currently not available. The purpose of this study was to perform bone density analyses including patient specific calibration in an RSA cohort based on preoperative CT imaging. It was hypothesized that preoperative CT bone density measures would provide objective quantification of the patients' humeral bone quality. METHODS: This study consisted of three parts, (1) analysis of a patient-specific calibration method in cadaveric CT scans, (2) retrospective application in a clinical RSA cohort, and (3) clustering and classification with machine learning models. Forty cadaveric shoulders were scanned in a clinical CT and compared regarding calibration with density phantoms, air muscle, and fat (patient-specific) or standard Hounsfield unit. Post-scan patient-specific calibration was used to improve the extraction of three-dimensional regions of interest for retrospective bone density analysis in a clinical RSA cohort (n=345). Machine learning models were used to improve the clustering (Hierarchical Ward) and classification (Support Vector Machine (SVM)) of low bone densities in the respective patients. RESULTS: The patient-specific calibration method demonstrated improved accuracy with excellent intraclass correlation coefficients (ICC) for cylindrical cancellous bone densities (ICC>0.75). Clustering partitioned the training data set into a high-density subgroup consisting of 96 patients and a low-density subgroup consisting of 146 patients, showing significant differences between these groups. The SVM showed optimized prediction accuracy of low and high bone densities compared to conventional statistics in the training (accuracy=91.2%; AUC=0.967) and testing (accuracy=90.5 %; AUC=0.958) data set. CONCLUSION: Preoperative CT scans can be used to quantify the proximal humeral bone quality in patients undergoing RSA. The use of machine learning models and patient-specific calibration on bone mineral density demonstrated that multiple 3D bone density scores improved the accuracy of objective preoperative bone quality assessment. The trained model could provide preoperative information to surgeons treating patients with potentially poor bone quality.

Glenoid lateralization in reverse shoulder arthroplasty: metal vs. bone offset in different implant designs.

Background: Higher bone or metal glenoid offset in reverse shoulder arthroplasty (RSA) reduces scapular notching, improves range of motion (ROM), and reduces postoperative instability. This retrospective multicenter study compared two implant designs to evaluate the short-term clinical and radiologic results of bone increased offset RSA (BIO-RSA) and metal increased offset RSA (MIO-RSA) in reverse shoulder. We hypothesized no difference between groups. Methods: This study analyzed n = 62 BIO-RSA and n = 90 MIO-RSA cases with a mean follow-up of 29.7 ± 6.0 months (BIO-RSA, range 24-49 months) and 24.0 ± 1.1 months (MIO-RSA, range 22-28 months). A 145°-onlay humeral stem was utilized in BIO-RSA cases, while a 135°-semi-inlay humeral stem was implanted in all MIO-RSA cases. Preoperative and postoperative radiologic imaging was reviewed to identify signs of scapular notching. Additionally, lateralization was evaluated according to Erickson et al. The constant score, subjective shoulder value, and ROM were evaluated during the baseline and follow-up consultations, and the findings of both groups were subsequently compared. Results: Scapular notching was observed in 7.0% (n = 8) of MIO-RSA cases and 8.1% (n = 5) of BIO-RSA cases (P = .801). MIO-group had a higher lateralization angle (P = .020) and the BIO-group had a higher distalization angle (P = .005). At baseline, mean constant score in the MIO-RSA group was higher than in the BIO-RSA group (P < .001), and it significantly increased to 67.8 ± 12.1P (MIO-RSA) and 69.5 ± 12.3P (BIO-RSA) to a similar level (P = .399). ROM improved in both groups with no significant difference between the two groups at follow-up. Conclusion: BIO-RSA and MIO-RSA in two distinct implant designs provide comparable short-term outcomes with a similar increase in shoulder function with notable variations in the lateralization and distalization angles between both implants. Scapular notching was rarely seen and unaffected by the method of glenoid lateralization. Follow-up investigations of both techniques are necessary to complement and track changes in the long-term outcome.

Carpal tunnel release in the dialysis-dependent population: Incidence and outcomes.

Level of evidence: Level III, retrospective case-control study. Background: The association between dialysis and carpal tunnel syndrome is well-established. As the number of patients living with dialysis-dependent end-stage renal disease (ESRD) increases, it is important that we understand outcomes after carpal tunnel release in this population. Purpose: To investigate (1) the prevalence of carpal tunnel syndrome (CTS) in dialysis-dependent patients, (2) the incidence of carpal tunnel release (CTR), and (3) the differences in complications after CTR between hemodialysis patients, peritoneal dialysis patients, and matched controls. Patients and methods: Querying the PearlDiver database, we determined prevalence of CTS and incidence of CTR in dialysis-dependent and control patients. We compared peritoneal dialysis (PD) patients to matched populations of hemodialysis (HD) patients and non-dialysis-dependent controls. Complications were identified, including hospital admission, emergency department visits, infection, revision surgery, and postoperative chronic regional pain syndrome (CRPS). Results: The rates of CTS and CTR in dialysis patients were significantly increased relative to controls. Dialysis-dependent patients had increased rates of hospital admission within 30 days postoperatively (OR 4.13, P â€‹< â€‹.0001 for PD; OR 4.42, P â€‹< â€‹.0001 for HD), infection within 6 months postoperatively (OR 2.32, P â€‹= â€‹.013 for PD; OR 3.20, P â€‹< â€‹.0001 for HD), and need for revision CTR (OR 2.04, P â€‹= â€‹.009 for PD; OR 1.62, P â€‹= â€‹.037 for HD). Emergency department presentation within 30 days postoperatively was less common in PD vs HD (OR 0.63, P â€‹= â€‹.038). Conclusions: When compared to the control population, patients undergoing dialysis are more likely to be diagnosed with carpal tunnel syndrome, undergo carpal tunnel release, and are at significantly increased risk for perioperative complications.

The impact of 3-dimensional humeral planning and standard transfer instrumentation on reconstruction of native humeral anatomy for anatomic total shoulder arthroplasty.

BACKGROUND: Preoperative 3-dimensional (3D) computed tomography (CT)-based planning for anatomic total shoulder arthroplasty (TSA) has grown in popularity in the past decade with the primary focus on the glenoid. Little research has evaluated if humeral planning has any effect on the surgical execution of the humeral cut or the positioning of the prosthesis. METHODS: Three surgeons performed a prospective study using 3D-printed humeri printed from CTs of existing patients, which were chosen to be -3, -1, 0, 1, and 3 standard deviations of all patients in a large database. A novel 3D printing process was used to 3D print not only the humerus but also all 4 rotator cuff tendons. For each surgical procedure, the printed humerus was mounted inside a silicone shoulder, with printed musculature and skin, and with tensions similar to human tissue requiring standard retraction and instruments to expose the humerus. Three phases of the study were designed. In phase 1, humeral neck cuts were performed on all specimens without any preoperative humeral planning; in phase 2, 3D planning was performed, and the cuts and implant selection were repeated; in phase 3, a neck-shaft angle (NSA) guide and digital calipers were used to measure humeral osteotomy thickness to aid in the desired humeral cut. All humeri were digitized. The difference between the prosthetic center of rotation (COR) and ideal COR was calculated. The percentage of patients with a varus NSA was calculated for each phase. The difference in planned and actual cut thickness was also compared. RESULTS: For both 3D change in COR and medial to lateral change in COR, use of preoperative planning alone and with standard transfer instrumentation resulted in a significantly more anatomic restoration of ideal COR. The deviations from planned cut thickness decreased with each phase: phase 1: 2.6 ± 1.9 mm, phase 2: 2.0 ± 1.3 mm, phase 3: 1.4 ± 0.9 mm (P = .041 for phase 3 vs. phase 1). For NSA, in phase 1, 7 of 15 (47%) cases were in varus; in phase 2, 5 of 15 (33%) were in varus; and in phase 3, 1 of 15 (7%) cases was in varus (P = .013 for phase 3 vs. phase 1). CONCLUSIONS: Use of preoperative 3D humeral planning for stemless anatomic TSA improved prosthetic humeral COR, whether performed with or without standard transfer instrumentation. The use of an NSA cut guide and calipers to measure cut thickness significantly reduced the percentage of varus humeral cuts and deviation from planned cut thickness.

The effect of factors from different time points on psychological readiness following ACL reconstruction.

OBJECTIVE: The purpose of this study was to examine factors correlated with psychological readiness to return to activity after ACLR. DESIGN: cross sectional study. SETTING: controlled laboratory. PARTICIPANTS: 164 patients (82 M/82 F, 22.5 ± 8.9yr, 171.6 ± 11.0 cm, 77.4 ± 18.6 kg, 8.6 ± 3.4 months post-ACLR) participated in this study after a primary, isolated, and uncomplicated ACLR. MAIN OUTCOME MEASURES: ACL Return to Sport Index (ACL-RSI). RESULTS: ACL-RSI scores demonstrated a weak positive correlation with activity level at the time of injury and a fair positive correlation with activity level at the time of post-operative testing (p-values: 0.004, <0.001). ACL-RSI scores showed a statistically significant fair negative correlation with pain and a moderate negative correlation with kinesiophobia during rehabilitation (p-values: <0.001, <0.001). There was no statistical significance between ACL-RSI and the surgical variables (p-value range: 0.10-0.61). CONCLUSIONS: Outcomes from testing during postoperative rehabilitation were most correlated with psychological readiness to return to activity after ACLR. Increased pain and kinesiophobia were associated with a decreased psychological readiness. Increased activity level prior to injury and activity level at the time of testing during rehabilitation were both correlated with increased psychological readiness. Psychological readiness to return to activity may need to be customized based on potentially modifiable patient-specific factors during the post-operative rehabilitation.

Does timing of total elbow arthroplasty after distal humerus fracture affect 2-year complication rates?

BACKGROUND: Open reduction internal fixation (ORIF) remains the gold standard for adult distal humerus fractures (DHF). However, indications for total elbow arthroplasty (TEA) continue to expand and the incidence of primary and salvage TEA for DHF has increased. The objective of this study was to compare complication and reoperation rate for acute versus delayed primary and salvage TEA performed for DHF. METHODS: Patients who underwent TEA for DHF were identified in the PearlDiver database. Patients were sorted into three cohorts: (1) acute TEA (within 2 weeks of diagnosis), (2) delayed TEA (between 2 weeks and 6 months after diagnosis), and (3) salvage TEA (after failed ORIF, malunion, nonunion, delayed treatment between 6 months-1 year or post-traumatic arthritis). Multivariate analysis was utilized to assess for confounding variables and covariates when identify differences in complications between cohorts. RESULTS: 788 patients underwent acute TEA, 213 patients underwent delayed TEA, and 422 patients underwent salvage TEA after DHF. The incidence of PJI (8.5% vs. 3.4%, odds ratio (OR) 2.60, P=0.002) and triceps injury (2.4% vs. 0.4%, OR 6.29, P=0.012) were higher in the delayed compared to acute cohort. The incidence of revision (8.5% vs. 2.1%, OR 3.76, P< 0.001), periprosthetic fracture (4.3% vs. 1.1%, OR 3.64, P=0.002), PJI (14.7% vs 3.4%, OR 4.36, P< 0.001), triceps injury (2.6% vs. 0.4%, OR 5.70, P=0.008), and wound complications (6.9% vs 2.9%, OR 2.33, P=0.002) were higher in the salvage compared to acute cohort. There was an increased rate of revision (8.5% vs. 1.9%, OR 6.08, P=0.002) in the salvage compared to delayed cohort. CONCLUSION: Patients undergoing salvage TEA after DHF have increased rates of at 2 years postoperatively including revision, periprosthetic fracture, PJI, triceps injury, and wound complications. The salvage cohort also had an increased risk of revision when compared to the delayed cohort. However, other than revision rates, patients in the salvage and delayed cohorts have similar postoperative complication rates.

The subcoracoid distance is correlated with pain and internal rotation after reverse shoulder arthroplasty.

Background: A proposed etiology of anterior shoulder pain and limited internal rotation after reverse shoulder arthroplasty (RSA) is impingement of the humeral component on the coracoid or conjoint tendon. The primary goal of this study was to investigate radiographic surrogates for potential coracoid or conjoint tendon impingement and their relationship to postoperative pain and internal rotation after RSA. Methods: A retrospective review of a clinical registry was performed to identify patients with (1) primary RSA, (2) minimum 2-year clinical follow-up, and (3) satisfactory postoperative axillary lateral radiographs. The primary radiographic measurement of interest was the subcoracoid distance (SCD), defined as the distance between the posterior aspect of the coracoid and the anterior glenosphere. Additional measurements were as follows: anterior glenosphere overhang, posterior glenosphere overhang, native glenoid width, lateralization of glenosphere relative to the coracoid tip, lateralization shoulder angle, and distalization shoulder angle. The primary clinical outcome of interest was the 2-year postoperative Visual Analog Scale score. Secondary outcomes were (1) internal rotation (IR) defined by spinal level (IRspine), (2) IR at 90 degrees of abduction, (3) American Shoulder and Elbow Surgeons score, (4) forward flexion, and (5) external rotation at 0 degrees of abduction. Linear regression analyses were used to evaluate the relationship of the various radiographic measures on the clinical outcomes of interest. Results: Two hundred seventeen patients were included. There was a statistically significant relationship between the SCD and Visual Analog Scale scores: B = -0.497, P = .047. There was a statistically significant relationship between the SCD and IRspine: B = -1.667, P < .001. Metallic lateralization was also positively associated with improving IRspine; increasing body mass index was negatively associated. There was a statistically significant relationship between the SCD and IR at 90 degrees of abduction: B = 5.844, P = .034. Conclusion: For RSA with a 135° neck shaft angle and lateralized glenoid, the postoperative SCD has a significant association with pain and IR. Decreasing SCD was associated with increased pain and decreased IR, indicating that coracoid or conjoint tendon impingement may be an important and potentially under-recognized etiology of pain and decreased IR following RSA. Further investigations aimed toward identifying a critical SCD to improve pain and IR may allow surgeons to preoperatively plan component position to improve clinical outcomes after RSA.

Rates of subacromial notching are low following reverse shoulder arthroplasty with a 135° inlay humeral component and a lateralized glenoid.

Background: Lateralization in reverse shoulder arthroplasty (RSA) decreases bony impingement and improves rotational range of motion, but has been theorized to increase the risk of subacromial notching (SaN). The purpose of this study was to evaluate the presence of SaN following RSA and its relationship with lateralization with a 135° inlay humeral component. The secondary purpose was to assess the association of SaN with functional outcomes. Methods: A retrospective review was performed from a multicenter prospectively collected database on patients who underwent primary RSA from 2015 to 2021. All RSAs were performed with a 135° inlay humeral component. SaN was defined as bony erosion with sclerotic margins on the undersurface of the acromion on final follow-up radiographs not present preoperatively. Postoperative implant positioning (inclination, distalization, and lateralization) were evaluated on minimum 1-year postoperative radiographs. Regression analyses were performed on implant and clinical variables to assess for risk factors. A separate analysis was performed to determine the association of SaN with clinical outcomes. Results: SaN was identified in 13 out of 442 shoulders (2.9%). Age, sex, body mass index, smoking status, diabetes mellitus, arm dominance had no relationship with SaN. Neither glenoid sided lateralization nor humeral offset were associated with SaN risk. Other implant characteristics such as distalization, glenosphere size, and postoperative inclination did not influence SaN risk. The presence of SaN did not affect patient-reported outcomes (American Shoulder and Elbow Surgeons: P = .357, Visual Analog Scale: P = .210) or range of motion. Conclusion: The rate of SaN is low and not associated with glenoid or humeral prosthetic lateralization when using a 135° inlay humeral component. When SaN occurs, it is not associated with functional outcomes or range of motion at short-term follow-up.

Novel 3D MRI-based volumetric assessment of rotator cuff musculature demonstrates stronger correlation with preoperative functional status when compared to the Goutallier grading scheme.

BACKGROUND: The Goutallier classification (GC) is used to assess fatty atrophy in rotator cuff (RC) tears, yet limitations exist. A battery of 3-dimensional (3D) magnetic resonance imaging (MRI) volumetric scores (VSs) was developed to provide comprehensive characterization of RC pathology. The purposes of this study were to (1) describe the correlation between GC and VSs for supraspinatus changes in RC tears, (2) characterize the chronicity of RC tears using a battery of 12 VS measurements, and (3) compare GC and VSs to determine which method most closely corresponds with preoperative patient-reported outcome measures (PROMs). METHODS: Preoperative shoulder MRIs were reviewed after arthroscopic RC repair. Preoperative GC stage and Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) and pain interference (PI) scores were collected. The battery of VSs included fat infiltration (FIS), muscle size (MSS), and relative volume contribution (RCS) for each RC muscle. Backward linear regression was performed to compare GC stage with preoperative PROMIS PF and PI to determine which VS measurement most closely correlated with preoperative PROMs. RESULTS: Eighty-two patients underwent RC repair (mean age 55 ± 8.2 years, 63% male, 68% GC stage ≤1). In evaluation of the supraspinatus, there was a moderate positive correlation between GC and FIS (r = 0.459, P < .001); strong negative correlations were observed between MSS (r = -0.800, P < .001) and RCS (r = -0.745, P < .001) when compared to GC. A negligible linear correlation was observed between GC and preoperative PROMIS PF (r = -0.106, P = .343) and PI (r = -0.071, P = .528). On multivariate analysis, subscapularis MSS (ß >0, P = .064) was a positive predictor and subscapularis FIS (ß <0, P = .137), teres minor MSS (ß <0, P = .141), and FIS (ß <0, P = .070) were negative predictors of preoperative PF (r = 0.343, P = .044); in contrast, supraspinatus MSS (ß >0, P = .009) and FIS (ß >0, P = .073), teres minor FIS (ß >0, P = .072), and subscapularis FIS (ß >0, P = .065) were positive predictors of preoperative PI (r = 0.410, P = .006). CONCLUSION: Although the criterion standard in evaluation of RC pathology, GC demonstrated negligible correlation with preoperative functional disability. Alternatively, a battery of 3D VSs showed strong correlation with GC through a quantitative, comprehensive evaluation of the RC unit including several moderate predictors of preoperative functional disability.

Posteroinferior glenosphere positioning is associated with improved range of motion following reverse shoulder arthroplasty with a 135° inlay humeral component and lateralized glenoid.

BACKGROUND: Optimal glenosphere positioning in a lateralized reverse shoulder arthroplasty (RSA) to maximize functional outcomes has yet to be clearly defined. Center of rotation (COR) measurements have largely relied on anteroposterior radiographs, which allow assessment of lateralization and inferior position, but ignore scapular Y radiographs, which may provide an assessment of the posterior and inferior position relative to the acromion. The purpose of this study was to evaluate the COR in the sagittal plane and assess the effect of glenosphere positioning with functional outcomes using a 135° inlay stem with a lateralized glenoid. METHODS: A retrospective review was performed on a prospectively maintained multicenter database on patients who underwent primary RSA from 2015 to 2021 with a 135° inlay stem. The COR was measured on minimum 2-year postoperative sagittal plain radiographs using a best-fit circle fit method. A best-fit circle was made on the glenosphere and the center was marked. From there, 4 measurements were made: (1) center to the inner cortex of the coracoid, (2) center to the inner cortex of the anterior acromion, (3) center to the inner cortex of the middle acromion, and (4) center to the inner cortex of the posterior acromion. Regression analysis was performed to evaluate any association between the position of the COR relative to bony landmarks with functional outcomes. RESULTS: A total of 136 RSAs met the study criteria. There was no relation with any of the distances with outcome scores (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, visual analog scale). In regard to range of motion (ROM), each distance had an effect on at least 1 parameter. The COR to coracoid distance had the broadest association with ROM, with improvements in forward flexion (FF), external rotation (ER0), and internal rotation with the arm at 90° (IR90) (P < .001, P = .031, and P < .001, respectively). The COR to coracoid distance was also the only distance to affect the final FF and IR90. For every 1-mm increase in this distance, there was a 1.8° increase in FF and 1.5° increase in IR90 (ß = 1.78, 95% confidence interval [CI] 0.85-2.72, P < .001, and ß = 1.53, 95% CI 0.65-2.41, P < .001; respectively). CONCLUSION: Evaluation of the COR following RSA in the sagittal plane suggests that a posteroinferior glenosphere position may improve ROM when using a 135° inlay humeral component and a lateralized glenoid.

A two-year comparison of reverse total shoulder arthroplasty mini-humeral tray and augmented mini-glenoid baseplate implants vs. standard implants.

BACKGROUND: Patients who undergo reverse total shoulder arthroplasty (RTSA) are getting younger with greater function expectations. This retrospective, longitudinal study of prospectively collected data compared perceived shoulder function and strength, active shoulder mobility, radiographic evidence of scapular notching, and implant survival over the initial 2-years post-RTSA among patient groups who received either standard central fixation point liner and glenoid baseplate implants, or lower size profile mini-humeral tray with offset trunnion options and mini-augmented glenoid baseplate implants. MATERIALS AND METHODS: Patients who underwent primary RTSA using standard central fixation point liner and glenoid baseplate implants (Group 1, n = 180) were compared with patients who underwent primary RTSA using lower size profile mini-humeral tray with offset trunnion options and mini-augmented glenoid baseplate implants (Group 2, n = 53) for active shoulder mobility, American Shoulder and Elbow Surgeons (ASES) score, perceived ability to lift 10 lbs (4.5 kg) overhead, radiographic evidence of scapular notching, and implant survival. Data was collected pre-surgery, 6-weeks, 6-months, 1-year, and 2-years post-RTSA (p ≤ 0.05). RESULTS: More Group 2 patients had more complex B or C Walch glenoid morphology, while Group 1 had more A1 or A2 types (p ≤ 0.001). Group 2 had greater active shoulder flexion at 6-months, 1-year, and 2-years (p ≤ 0.018) and external rotation (in adduction) at 6-months and 2-years (p ≤ 0.004) compared to Group 1, with higher ASES scores at 6-months and 2-years (p ≤ 0.026) (with small-to-medium effect sizes), and with more patients meeting or exceeding the minimal clinically important difference (MCID) at 2-years (p = 0.045) and patient acceptable symptomatic state (PASS) levels at 6-months, 1-year and 2-years (p ≤ 0.045). Scapular notching was identified in six of 53 (11.3%) Group 2 patients and in 32 of 180 (17.7%) Group 1 patients. Group 1 patients had more grade 2 or greater scapular notching grades compared to Group 2 (p = 0.04). Implant survival was comparable with Group 1 = eight of 180 (4.4%) and Group 2 = 1 of 53 (1.9%) of patients requiring removal for 95.6% and 98.1% implant survival, respectively. CONCLUSION: Limited scapular notching and excellent implant survival was observed in both groups. Despite including individuals with more complex glenoid deficiency, patients receiving the lower size profile implants generally displayed better active shoulder mobility and perceived shoulder function compared to those who received standard implants. These patients also more frequently met or exceeded the MCID by 2-years post-RTSA and PASS levels by 6-months, 1-year, and 2-years post-RTSA, with lower scapular notching grades. LEVEL OF EVIDENCE: Retrospective comparative study.

Stemless anatomic total shoulder arthroplasty is associated with less early postoperative pain.

Background: Improvements in pain control after shoulder arthroplasty with a reduction in narcotic use continues to be an important postoperative goal. With the increased utilization of stemless anatomic total shoulder arthroplasty (aTSA), it is relevant to compare between stemmed and stemless arthroplasty to assess if there is any association between this implant design change and early postoperative pain. Methods: Patients from a multicenter, prospectively-maintained database who had undergone a stemless aTSA with a minimum of two year clinical follow-up were retrospectively identified. Patients who underwent aTSA with a short stem were identified in the same registry, and matched to the stemless aTSA patients by age, sex and preoperative pain score. The primary study outcome was the Visual Analog Scale pain score. Secondary pain outcomes were the American Shoulder and Elbow Surgeons shoulder pain subscore, Western Ontario Osteoarthritis of the Shoulder physical symptoms subscore, and the Single Assessment Numeric Evaluation score. Finally, the percentage of patients who could sleep on the affected shoulder was assessed for each group. These pain-related clinical outcomes were assessed and compared preoperatively, and postoperatively at 9 weeks, 26 weeks, one year and two years. For all statistical comparisons, P > .05 was considered significant. Results: 124 patients were included in the study; 62 in each group. At 9 weeks after surgery, statistically significantly improved pain control was reported by patients undergoing stemless aTSA, as assessed by the Visual Analog Scale (stemless: 1.5, stemmed: 2.5, P = .001), American Shoulder and Elbow Surgeons pain subscore (stemless: 42.4, stemmed: 37.3, P < .001), Western Ontario Osteoarthritis of the Shoulder Physical Symptoms (stemless: 80.3, stemmed: 73.1, P = .006) and Single Assessment Numeric Evaluation (stemless: 58.1, stemmed: 47.4, P = .011). Patients who underwent a stemless aTSA were significantly more likely to be able to sleep on the affected shoulder at 9 weeks (29% vs. 11%, odds ratio 3.2, 95% confidence interval 1.2-8.4, P = .014). By 26 weeks postoperatively, there were no differences in all pain-specific outcomes. At two years postoperatively, patient-reported outcomes, range of motion, and strength measures were all similar between the two cohorts. Conclusion: Stemless aTSA provides earlier improvement in postoperative shoulder pain compared to matched patients undergoing short-stem aTSA. Additionally, earlier return to sleeping on the affected shoulder was reported in the stemless aTSA group. The majority of these differences dissipate by 26 weeks postoperatively and there were no differences in pain, patient-reported outcomes, range of motion or strength measures between stemless and short-stem aTSA at 2 years postoperatively.

Obesity is associated with improvement in functional outcome but lower internal rotation after reverse shoulder arthroplasty.

Background: The role of obesity as an independent risk factor for increased complications following reverse shoulder arthroplasty (RSA) continues to generate debate. While no standardized body mass index (BMI) cutoff values for shoulder arthroplasty exist, many surgeons are concerned about the potential for poor outcomes and decreased range of motion (ROM) in patients with a high BMI. The purpose of this study was to compare functional outcomes in obese and nonobese patients preoperatively and at short-term follow-up after RSA. Methods: A retrospective review was performed of a prospectively maintained, multicenter database of primary RSAs performed by 14 surgeons between 2015 and 2019 with minimum 2-year follow-up. A total of 245 patients met the study criteria, including 111 obese (BMI >30) and 134 nonobese (BMI <30) patients. Patient-reported outcomes (PROs) as well as ROM measurements were compared between the 2 groups. Results: At baseline, obese patients had significantly lower American Shoulder and Elbow Surgeons (36.6 vs. 42.0, P = .014), Western Ontario Osteoarthritis of the Shoulder scores (33.1 vs. 37.8, P = .043), external rotation at 90° (19° vs. 28°, P = .007), internal rotation (IR) spinal level (L5 vs. L4, P = .002), and belly press strength (P = .003) compared to the nonobese cohort. There were no statistical differences in 2-year outcomes (PROs, ROM, and strength) other than a worse IR (spinal level) in the low BMI group (L4 vs. L3, P = .002). In linear regression analyses controlling for confounding variables, increasing BMI was negatively correlated with preoperative external rotation (B = -0.591, P = .034) and preoperative IR spinal level (B = 0.089, P = .002). Increasing BMI was not correlated with postoperative external rotation at 90° (B = 0.189, P = .490) but was associated with worse postoperative IR by spinal level (B = 0.066, P = .043). Conclusions: Obese patients have greater restrictions in external and internal rotation as well as American Shoulder and Elbow Surgeons and Western Ontario Osteoarthritis of the Shoulder scores at baseline prior to RSA. However, there are no major differences in postoperative PROs or ROM measurements between obese and nonobese patients apart from a worse active IR by spinal level in the obese group (L4 vs. L3, P = .002). This study suggests that an RSA procedure does not need to be restricted solely based on BMI.

Robert H. Cofield, MD, Award for Best Oral Presentation 2023: Up to 8 mm of glenoid-sided lateralization does not increase the risk of acromial or scapular spine stress fracture following reverse shoulder arthroplasty with a 135° inlay humeral component.

BACKGROUND: Glenoid-sided lateralization in reverse shoulder arthroplasty (RSA) decreases bony impingement and improves rotational range of motion, but has been theorized to increase the risk of acromial or scapular spine fractures (ASFs). The purpose of this study was to assess if glenoid-sided lateralization even up to 8 mm increases the risk for stress fracture following RSA with a 135° inlay humeral component. METHODS: A retrospective review was performed from a multicenter prospectively collected database on patients who underwent primary RSA from 2015 to 2021. All RSAs were performed with a 135° inlay humeral component. Varying amounts of glenoid lateralization were used from 0 to 8 mm. Preoperative radiographs were reviewed for the presence of acromial thinning, acromiohumeral distance (AHD), and inclination. Postoperative implant position (distalization, lateralization, and inclination) as well as the presence of ASF was evaluated on minimum 1-year postoperative radiographs. Regression analyses were performed on component and clinical variables to assess for factors predictive of ASF. RESULTS: Acromial or scapular spine fractures were identified in 26 of 470 shoulders (5.5%). Glenoid-sided lateralization was not associated with ASF risk (P = .890). Furthermore, the incidence of fracture did not vary based on glenoid-sided lateralization (0-2 mm, 7.4%; 4 mm, 5.6%; 6 mm, 4.4%; 8 mm, 6.0%; P > .05 for all comparisons). RSA on the dominant extremity was predictive of fracture (odds ratio [OR] 2.21, 95% confidence interval [CI] 1.20-5.75; P = .037), but there was no relationship between patient age, sex, preoperative acromial thinning, or diagnosis and risk of fracture. Although there was no difference in mean postoperative AHD between groups (P = .443), the pre- to postoperative delta AHD was higher in the stress fracture group (2.0 ± 0.7 cm vs. 1.7 ± 0.7 cm; P = .015). For every centimeter increase in delta AHD, there was a 121% increased risk for fracture (OR 2.21, 95% CI 1.33-3.68; P = .012). Additionally, for every 1-mm increase in inferior glenosphere overhang, there was a 19% increase in fracture risk (P = .025). CONCLUSION: Up to 8 mm of glenoid-sided metallic lateralization does not appear to increase the risk of ASF when combined with a 135° inlay humeral implant. Humeral distalization increases the risk of ASF, particularly when there is a larger change between pre- and postoperative AHD or higher inferior glenosphere overhang. In cases of pronounced preoperative superior humeral migration, it may be a consideration to avoid excessive postoperative distalization, but minimizing bony impingement via glenoid-sided lateralization appears to be safe.

Mini-augmented glenoid baseplate and mini-humeral tray reverse total shoulder arthroplasty implant comparisons: two-year clinical outcomes.

BACKGROUND: Augmented glenoid baseplate and offset humeral tray reverse total shoulder arthroplasty (RTSA) implants may decrease the mechanical impingement that creates scapular notching and improve shoulder function. This study evaluated the clinical efficacy of three different RTSA glenoid baseplate and offset humeral tray combinations for patient-reported shoulder function, pain and instability, radiographic imaging evidence of glenoid baseplate or humeral stem subsidence and migration, bony changes associated with implant loosening, and scapular notching over the initial 2 years post-RTSA. Primary outcomes included active shoulder mobility, perceived function, pain, instability, scapular notching, and implant survival. METHODS: Sixty-seven patients from 6 research sites received one of three different glenoid baseplate and humeral tray combinations. Group 1 (n = 21) received a mini-augmented glenoid baseplate with a standard humeral tray; Group 2 (n = 23) received a standard glenoid baseplate and a mini-humeral tray with 3 trunnion offset options; Group 3 (n = 23) received both a mini-augmented glenoid baseplate and a mini-humeral tray with 3 trunnion offset options. Subjects underwent radiologic evaluation, completed the ASES scale, the EQ-5D-5L quality of life scale, VAS shoulder pain and instability questions, and active shoulder mobility measurements pre-operatively, and 6-weeks, 6-months, 1-2 years post-RTSA. RESULTS: Improved active shoulder mobility, quality of life, perceived function, decreased shoulder pain and instability, excellent implant survival and minimal scapular notching were observed for all groups. Group 3 had better overall active shoulder mobility than the other groups and better perceived function than Group 1. CONCLUSION: The group that received the mini-augmented glenoid baseplate and mini-humeral tray combination had better overall active shoulder flexion, external rotation at 90° abduction, and internal rotation. This group also had better perceived shoulder function compared to the group that received a mini-augmented glenoid baseplate with a standard humeral tray.

Evaluation of Achilles Tendon Stiffness as Measured by Shear Wave Elastography in Female College Athletes Compared With Nonathletes.

BACKGROUND: We sought to utilize a noninvasive technology to assess the effects of activity on Achilles tendon stiffness and define baseline Achilles tendon stiffness in female college athletes compared with nonathletes using tendon shear wave velocity as a marker for tendon stiffness. HYPOTHESIS: Training status and exercise may affect Achilles tendon stiffness. LEVEL OF EVIDENCE: Level 4. METHODS: A total of 32 college-age female athletes were prospectively enrolled (n = 17 varsity athletes and n = 15 nonathletes). Demographic characteristics, activity level, and previous injuries were recorded. Sonographic shear wave elastography (SWE) was used to assess Achilles tendon shear wave velocity bilaterally for all subjects, both at baseline and after 2 minutes of exercise. Student t tests were used to compare the mean elastography measurements between participants stratified by athlete status and pre/postexercise stimulus. Analysis of variance (ANOVA) was used to compare the mean proximal, middle, and distal Achilles tendon elastography measurements. RESULTS: As seen by a greater mean shear wave velocity (8.60 ± 1.58 m/s vs 8.25 ± 1.89 m/s; P = 0.02), athletes had stiffer tendons than nonathletes. Exercise stimulus decreased average tendon shear wave velocity (8.57 ± 1.74 m/s vs 8.28 ± 1.72 m/s; P = 0.05). Tendon shear wave velocity was greatest proximally and least distally with significant differences between each region (P < 0.001). In addition, there was a significant 2-way interaction between weekly training status and foot dominance (P = 0.01). Post hoc analysis showed that this result was due to differences in tendon shear wave velocity between the dominant and nondominant lower extremity in nonathletes (7.73 ± 2.00 m/s vs 8.76 ± 1.62 m/s; P < 0.001). CONCLUSION: Female varsity collegiate athletes have higher baseline Achilles tendon stiffness as measured by SWE compared with nonathletes. Mean tendon stiffness varies based on Achilles measurement location. SWE is a quick, cost-effective, and noninvasive imaging modality that can be used to evaluate tendon stiffness and elasticity. CLINICAL RELEVANCE: SWE is an efficient and noninvasive imaging modality that can evaluate dynamic tendon stiffness and elasticity. SWE may be helpful to assess injuries in female college athletes and may play a role in risk stratification or clinical follow-up. In theory, SWE could be used to identify athletes with increased elasticity as a marker for potential risk for rupture in this population.

Influence of backside seating parameters and augmented baseplate components in virtual planning for reverse shoulder arthroplasty.

BACKGROUND: The primary goal of this investigation was to examine the influence of a backside seating percentage variable on volume of reamed bone and contact area in virtual planning for glenoid baseplate placement for reverse total shoulder arthroplasty (RTSA). The secondary goal was to assess how the option of augmented glenoid baseplate components affected reamed volume and cortical contact area of virtually positioned baseplates. METHODS: Nine surgeons virtually planned 30 RTSA cases using a commercially available software system. The 30 cases were chosen to span a spectrum of glenoid deformity. The study consisted of 3 phases. In phase 1, cases were planned with the backside seating percentage blinded and without the option of augmented baseplate components. In phase 2, the backside seating parameter was unblinded. In phase 3, augmented baseplate components were added as an option. Implant version and inclination were recorded. By use of computer-assisted design models, total volume of bone reamed, as well as reamed cortical volume and cancellous volume, was calculated. Total, cortical, and cancellous baseplate contact areas were also calculated. Finally, total glenoid lateralization was calculated for each phase and compared. RESULTS: Mean implant version was clinically similar across phases but was statistically significantly lower in phase 3 (P = .006 compared with phase 1 and P = .001 compared with phase 2). Mean implant inclination was clinically similar across phases but was statistically significantly lower in phase 3 (P < .001). Phase 3 had statistically significantly lower cancellous and total reamed bone volumes compared with phase 1 and phase 2 (P < .001 for all comparisons). Phase 3 had statistically significantly larger cortical contact area, lower cancellous contact area, and larger total contact area compared with phase 1 and phase 2 (P < .001 for all comparisons). Phase 3 had significantly greater glenoid lateralization (mean, 10.5 mm) compared with phase 1 (mean, 7.8 mm; P < .001) and phase 2 (mean, 7.9 mm; P < .001). CONCLUSIONS: Across a wide range of glenoid pathology during virtual surgical planning, experienced shoulder arthroplasty surgeons chose augmented baseplates frequently, and the option of a full-wedge augmented baseplate resulted in statistically significantly greater correction of glenoid deformity, improved total and cortical baseplate contact area, less cancellous reamed bone, and greater glenoid lateralization. Backside seating information does not have a significant impact on how glenoid baseplates are virtually positioned for RTSA, nor does it impact the baseplate contact area or volume of reamed bone.

No Deficits in Functional Outcomes of the Contralateral Limb Are Seen When the Hamstring Is Harvested for Augmentation of Small Diameter Ipsilateral Hamstring Autograft.

Purpose: To evaluate clinical outcomes of the contralateral, nonoperative limb in patients undergoing contralateral hamstring (HS) autograft harvest compared with patients undergoing ipsilateral HS autograft harvest alone. Methods: This study included 96 patients who underwent isolated anterior cruciate ligament reconstruction (ACLR) using 4-stranded HS autograft (n = 85) or 4-stranded HS autograft augmented with contralateral HS (n = 13) due to inclusion of ipsilateral graft diameter <8 mm. Isokinetic flexion and extension strength and dynamic performance of the ipsilateral and contralateral limbs and limb symmetry index (LSI) were evaluated at 6 months' postoperatively. Rates of contralateral native ACL tear at minimum 2 years also were compared. For all comparisons, P < .05 was considered statistically significant. Results: Normalized isokinetic knee flexion and extension strength of the contralateral limb did not differ between cohorts (P = .34; P = .21, respectively). LSI for knee extension peak torque and knee flexion peak torque did not differ between cohorts (P = .44; P = .67, respectively). No difference in LSI was seen for any dynamic performance testing (single leg hop, P = .97; triple leg hop, P = .14; 6-m timed hop, P = .99). No difference was observed in International Knee Documentation Committee (P = .99) or Knee Injury and Osteoarthritis Outcome Score subscale measures (P = .39-.86). No difference in rates of contralateral knee native ACL tears were seen between cohorts (HS autograft + contralateral HS augmentation, n = 2, 15.4%; HS autograft, n = 7, 8.4%; P = .26). Conclusions: In this study, at the time of return to sport, we found no differences in contralateral limb functional performance or limb symmetry measurements between patients undergoing contralateral HS autograft harvest for augmentation of smaller (<8 mm) diameter HS autografts harvested from the injured extremity. Level of Evidence: Level III, retrospective cohort study.

Impact of Biologic Augmentation on Revision Surgery Rates After Meniscus Repair: A Matched-Cohort Analysis of 3420 Patients.

Background: Platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC) have gained popularity in recent years as biologic approaches to potentially augment healing after meniscus repair. There have been few studies comparing outcomes in patients undergoing meniscus repair with versus without biologic augmentation and, furthermore, little clarity on the role of biologic augmentation for meniscus repairs performed with concomitant anterior cruciate ligament reconstruction (ACLR). Purpose: To determine the association of BMAC or PRP augmentation with revision surgery after both isolated meniscus repair and meniscus repair performed concomitantly with ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: The PearlDiver Mariner dataset was queried to identify all patients who underwent primary meniscus repair, both with and without concomitant ACLR, and who received ipsilateral BMAC or PRP at the time of surgery. Patients who underwent similar surgery but without BMAC or PRP augmentation were then identified and matched in a 5:1 ratio according to age, sex, body mass index, and various comorbidities to 3 separate BMAC/PRP augmentation groups: overall cohort (with and without ACLR), repair with concomitant ACLR, and isolated repair. The primary outcome was revision meniscus surgery (meniscectomy or revision meniscus repair). Results: Overall, 3420 patients (570 with BMAC/PRP augmentation; 2850 matched controls without augmentation) were included. There were no significant differences in the reported demographics or comorbidities between any of the BMAC/PRP groups and their respective matched controls (P > .05 for all comparisons). There was no difference in revision rate between BMAC/PRP-augmented isolated meniscus repairs and matched controls (P = .235). Patients who underwent BMAC/PRP-augmented meniscus repair with concomitant ACLR experienced a significantly lower incidence of revision surgery compared with matched controls without BMAC/PRP augmentation (5.2% vs 7.9% respectively; odds ratio, 0.41; 95% CI, 0.27-0.63; P < .001), but the number of revisions was relatively small. Conclusion: There was no association between BMAC or PRP augmentation and the incidence of revision surgery after isolated primary meniscus repair. There was a statistically significant decrease in the rate of revision meniscus surgery when BMAC or PRP was used to augment meniscus repairs in the setting of concurrent ACLR; however, the overall revision rates were small.