Factors associated with improvement or loss of internal rotation after reverse shoulder arthroplasty

The Influence of the Joint Volume on the Prevention of Impingement and Elbow-at-Side Rotations: Could the 36 mm Sphere with an Inferior Offset of 2 mm Be the New Gold Standard?

Background: Reverse shoulder arthroplasty (RSA) improves shoulder function in cases of glenohumeral osteoarthritis and rotator cuff arthropathy. The design of the glenosphere influences mobility and scapular impingement. This study evaluates the impact of joint volume on the range of motion (RoM) and identifies design modifications to enhance mobility while reducing the impingement risk. Methods: Thirty-four cadaveric shoulders were implanted with the Aequalis Reversed II® prosthesis in seven configurations: four with 36 mm spheres (centered, 2 mm eccentric, and lateralized by 5 mm and 7 mm) and three with 42 mm spheres (centered, and lateralized by 7 mm and 10 mm). The joint volumes (inferior, anteroinferior, and posteroinferior) were measured via 3D CT scans. The RoM in adduction and elbow-at-side rotations (IR1 and ER1) was recorded. A statistical analysis identified threshold joint volumes correlating with improved mobility. Results: Larger joint volumes correlated with enhanced mobility. The 42 mm spheres demonstrated better adduction and ER1 compared to those of the 36 mm spheres (p < 0.0001). An inferior volume > 5000 mm3 and anteroinferior/posteroinferior volumes >2500 mm3 were thresholds for significant mobility improvement. Lateralization (≥7 mm) or inferior eccentricity (2 mm) improved the mobility with the 36 mm spheres, with the 36 + 2 configuration offering a practical balance for smaller patients. Conclusions: Increased joint volume enhances mobility, particularly in adduction and elbow-at-side rotations. A sphere with a 2 mm inferior offset or a 42 sphere with 7 mm lateralization optimizes the RoM while minimizing impingement risks. Patient-specific considerations, including anatomy and soft tissue tension, remain essential for optimal prosthesis selection.

Deltopectoral approach without subscapularis detachment for reverse shoulder arthroplasty. Technique and results of a safe and reproducible subscapularis-sparing approach

Background

The importance of the subscapularis for reverse total shoulder arthroplasty has been demonstrated, especially for internal rotation and stability. In a deltopectoral approach, a detachment of the subscapularis is performed (tenotomy, tuberosity peeling, or osteotomy), but the tendon is not always repairable at the end. When it is repaired, healing is obtained in only 40%-76% of the cases, with potential consequences for the outcomes. The anterior muscle-sparing (AMS) approach is a deltopectoral approach with preservation of the subscapularis, providing a solution to these problems. We present the surgical technique and results.

Methods

In a retrospective study, we included our first 45 cases of reverse total shoulder arthroplasty performed with the AMS approach for a degenerative affection of the shoulder (massive rotator cuff tear, cuff tear arthropathy, primary glenohumeral arthritis, or rheumatoid arthritis), excluding traumatic and revision cases. The subscapularis was intact in all the cases. The mean age at inclusion was 74.1 years. No patients were lost at the minimum 24-month follow-up. All the patients underwent a clinical evaluation preoperatively and at the last follow-up, including Constant score, simple shoulder value, pain scale, and range of motion. An X-ray evaluation was conducted postoperatively and at the last follow-up to assess implant positioning and evolution.

Results

There was no intraoperative complication, and the mean operative time was 62 minutes. We observed a significant improvement in Constant score (from 36 to 70, P <.001), simple shoulder value (from 33 to 81, P <.001), pain (from 6.3 to 0.7, P <.001), strength (from 0.5 to 3.5, P <.001), and most of the active mobilities. Regarding internal rotation, 95% of the patients reached level L3 or higher. Glenoid positioning was considered optimal in more than 90% of the cases (inferior tilt and low position) without any occurrence of superior tilt or high position. The osteophytes could be totally removed in 8 out of 9 cases (88.9%). Six postoperative complications (13.3%) were reported: 1 infection (2.2%), 2 cases of traumatic glenoid loosening (4.4%), 2 acromion fractures (4.4%), and 1 hematoma (2.2%). There was no instability. Eighty percent of the patients could return home, with a mean hospital stay of 1.8 days.

Conclusion

The AMS approach is a safe and reproducible technique. The preservation of the subscapularis has potential benefits regarding internal rotation and stability. In the absence of tendon suture, rehabilitation can be started immediately without motion restriction, allowing for a fast recovery and return to autonomy.

Mid-Term Outcomes of a Rectangular Stem Design with Metadiaphyseal Fixation and a 135° Neck-Shaft Angle in Reverse Total Shoulder Arthroplasty

Background/Objectives: Classical reverse shoulder arthroplasty (RSA) with a high neck-shaft angle (NSA) of 155° has shown satisfactory outcomes. However, newer RSA designs aim to improve results by modifying the stem design. This study evaluates the 5-year outcomes of a stem design featuring a rectangular metadiaphyseal fixation and a 135° NSA. Methods: This prospective bicentric case series included and longitudinally followed up patients that were treated for cuff arthropathy, massive irreparable rotator cuff tears, or eccentric osteoarthritis using a non-cemented rectangular metadiaphyseal fixation stem with a 135° NSA (Univers Revers, Arthrex, Naples, FL, USA). Subjective and objective functional outcome scores (Constant-Murley Score (CS), Shoulder Pain and Disability Index (SPADI), and Subjective Shoulder Value (SSV)), range of motion (ROM), radiographic outcome, adverse events, complications, and quality of life were investigated. Results: This study enrolled 132 patients (59% female, mean age 75 years, SD 6). At the 5-year follow-up, subjective and objective outcomes significantly improved compared to baseline: CS (32.9 to 71.7, p < 0.001), SPADI (38.7 to 86.2, p < 0.001), and SSV (43.0 to 84.1, p < 0.001). ROM improved in flexion (80° to 142.4°, p < 0.001), abduction (71.5° to 130.2°, p < 0.001), internal rotation (p < 0.001), internal rotation at 90° abduction (12.7° to 45.0°, p < 0.001), and abduction strength (0.8 kg to 5.2 kg, p < 0.001). External rotation remained unchanged (32.1° to 32.0°, p = 0.125), but external rotation at 90° abduction improved (20.9° to 52.7°, p < 0.001). No signs of implant migration, subsidence, shift, tilt, alignment loss, or wear were observed, but scapular bone spur formation (11%), scapular notching grade 1 (10%), bone resorption (10%), and partial humeral radiolucent lines (1%) were reported. Conclusions: Rectangular stems with metadiaphyseal fixation and a 135° neck-shaft angle in RSA consistently improve shoulder function, showing no aseptic loosening and minimal radiological changes at 5 years.

Increased glenoid baseplate retroversion improves internal rotation following reverse shoulder arthroplasty

Background

Internal rotation after reverse total shoulder arthroplasty is often unchanged or minimally improved. The primary purpose of this study was to investigate the effects of glenoid baseplate version on postoperative internal rotation. The secondary purpose to investigate the effects of baseplate retroversion on external rotation (ER) and patient-reported outcomes (PROs).

Methods

A retrospective review was performed on a prospectively maintained multicenter database of patients who underwent primary reverse shoulder arthroplasty using a 135° humeral prosthesis and lateralized glenoid with minimum 2-year clinical follow-up. Preoperative and postoperative radiographs were reviewed by 2 independent observers who assessed preoperative glenoid version and postoperative glenoid baseplate version. Patients were stratified by postoperative retroversion (<10°, 10°-19° or >20°) and change in version from preoperative to postoperative (ΔRV). Primary outcomes were internal rotation with the arm at 90° (IR90) and internal rotation estimated to nearest spinal level (IRspine). Secondary outcomes were active ER in adduction (ER0), active ER with arm at 90° (ER90), forward flexion (FF), and PROs. Linear regression analyses and 1-way analysis of variance analyses were used for comparisons.

Results

Two hundred seventy-four patients with a mean of 71 years of age were included in the study. Patients with >10° of postoperative baseplate retroversion gained 20° of IR90 (P = .005) without loss of ER90 (P < .001) compared to patients with <10° of baseplate retroversion. More than 10° of postoperative baseplate retroversion was associated with significantly improved Constant-Murley scores (41.5, P = .007) and Single Assessment Numeric Evaluation scores (45.4, P = .047) compared to patients with less than <10° of baseplate retroversion. Patients with a ΔRV increase of >10° had significantly improved IR90 (P = .031) without loss of ER90 (P = .019). There was no correlation between ΔRV and IRspine, ER0 or FF, or PROs.

Conclusion

With a 135° and lateralized glenoid, postoperative baseplate retroversion of >10° was associated with significantly improved IR90, ER90, Constant-Murley, and Single Assessment Numeric Evaluation scores at 2-year follow-up compared to <10° retroversion. Additionally an increased ΔRV from preoperative to postoperative appears to improve IR90 without limiting ER0 or FF. While baseplate retroversion does not improve IRspine, overall function appears to be improved and therefore consideration may be given to accepting retroversion or intentionally retroverting the baseplate if fixation allows.

Predictors of Internal Rotation-Dependent Activities of Daily Living Performance and Favorable Satisfaction Despite Loss of Objective Internal Rotation After Reverse Shoulder Arthroplasty

INTRODUCTION

Previous research has determined that objective and subjective internal rotation (IR) may be discordant. The purpose of this study was to identify predictors of patient-reported ability to perform IR-dependent activities of daily living (IRADLs) and favorable patient satisfaction after reverse shoulder arthroplasty (RSA) despite the loss of objective IR.

METHODS

A single, institutional, shoulder arthroplasty database was queried for patients undergoing primary RSA with a minimum 2-year follow-up. Patients who were wheelchair bound or had a preoperative diagnosis of infection, fracture, or tumor were excluded. We first identified patients in the overall cohort that lost objective IR from pre- to postoperative assessment, defined as a one-point reduction in the eight-point Flurin scale. In this cohort, we identified patient characteristics that were predictive of patient-reported ability to perform IRADLs and overall patient satisfaction and thresholds in postoperative objective IR.

RESULTS

Out of 599 RSAs initially identified, 107 RSAs lost objective IR (45% female, mean age 70 years). On average, patients lost 1.7 IR score points pre- to postoperatively. Greater preoperative IR and lesser loss of objective IR pre- to postoperatively were associated with greater patient-reported ability to perform all 4 IRADLs (odds ratio 1.54 to 2.5), whereas female sex was associated with worse patient-reported ability to perform 3 IRADLs (odds ratio 0.26 to 0.36). We identified that patients with postoperative IR below the sacrum were unlikely to be able to perform IRADLs and those with postoperative IR at or above L4-L5 were likely to be satisfied.

CONCLUSION

Despite losing objectively assessed IR after RSA, many patients are still able to perform IRADLs and report favorable satisfaction as long as objective IR reaches L4/5. Female sex and postoperative IR below the sacrum were associated with the inability to perform IRADLs, whereas postoperative IR to or above L4-L5 was associated with subjective ratings of satisfaction.

Internal rotation limitation is prevalent following modern reverse shoulder arthroplasty and negatively affects patients' subjective rating of the procedure

BACKGROUND

Although forward elevation, abduction, and external rotation are often successfully restored, internal rotation (IR) is frequently not satisfactorily recovered following reverse shoulder arthroplasty (RSA), affecting patients' ability to perform certain daily activities. This study examined the prevalence of limited IR in patients receiving modern RSA and its impact on clinical outcomes and patient satisfaction with their RSA.

METHODS

A cross-sectional study was conducted on patients who had undergone primary RSA using a modern RSA prosthesis with a minimum 1-year follow-up. Patients returned for a research visit where they were examined for range of motion and surveyed for patient-reported outcome measures (PROMs) and subjective rating of the success level of their RSA. Postoperative range of motion data were compared with the preoperative data. The relationship of postoperative IR with PROMs and patients' subjective rating of RSA was analyzed. Logistic regression was performed to identify factors affecting patients' subjective rating of RSA.

RESULTS

A total of 78 patients met the criteria and completed the study. A significant portion (59%) reported subjective IR limitations, and 41% had objective IR limitations. Comparison of preoperative and postoperative IR showed that 24% had worsened IR, whereas 33% improved. Limited IR was associated with lower patients' subjective rating of RSA and negatively affected PROMs, especially when the dominant side was operated on. Regression analysis showed that limited IR was the only independent determining factor that was significantly associated with a lower subjective rating of RSA.

DISCUSSION

Despite advancements in RSA design, limited IR remains a prevalent issue, significantly affecting patients' satisfaction and clinical outcomes. This study underscores the need for setting appropriate expectations regarding IR through patient education and focused efforts to improve IR limitations in RSA patients, particularly on the dominant side.

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 (β = 1.78, 95% confidence interval [CI] 0.85-2.72, P < .001, and β = 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.

Conjoint tendon lengthening improves internal rotation following reverse total shoulder arthroplasty: a cadaveric study

BACKGROUND

Reverse shoulder arthroplasty (RSA) is a common procedure for treating a variety of shoulder pathologies. However, many patients struggle with postoperative internal rotation (IR) deficits, which often hinder their activities of daily living. The conjoint tendon provides an anatomic barrier that can impede the postoperative IR of the shoulder, and this study aims to evaluate the effect of a conjoint tendon lengthening on the glenohumeral range of motion (ROM) following RSA.

METHODS

This study used ten fresh-frozen cadaver specimens of the upper extremity. An RSA was implanted using a standard deltopectoral approach, and the ROM was assessed postimplantation. Following this, the conjoint tendon was identified and lengthened using a tendon sheath z-plasty, and the ROM was rerecorded. Statistical significance for the ROM gains after conjoint tendon lengthening was determined with a significance level of P < .05.

RESULTS

Following the lengthening of the conjoint tendon, there were statistically significant improvements in all ROMs (P < .05). Subjects demonstrated a notable gain in IR to the back by 10.3 cm (P < .01), and all ROMs increased by at least 10°, except for forward flexion, which increased by 6° (P < .001).

CONCLUSIONS

This study suggests that lengthening the conjoint tendon improves postoperative ROM of the glenohumeral joint after RSA, offering a potential solution to considerable IR deficits that are commonly encountered post-RSA. Subsequent clinical and biomechanical studies should assess the stability of the shoulder joint following conjoint tendon lengthening.

Intraoperative repair of functional subscapularis during RSA by deltopectoral approach could improve internal rotation but does not prevent anterior dislocation

INTRODUCTION

The role of the subscapularis following reverse shoulder arthroplasty (RSA) remains controversial as repair could restore adequate internal rotation and shoulder stability, but might compromise external rotation. The purpose of this multi-centre study, on a large cohort of RSAs performed using the deltopectoral approach, was to determine the effect of subscapularis preoperative status and intraoperative repair on range of motion, clinical scores and rates of complications at a minimum follow-up of 2 years.

HYPOTHESIS

Repair of a functional subscapularis grants better internal rotation and stability without compromising external rotation.

MATERIALS AND METHODS

We retrospectively reviewed records of all RSAs (n=916) performed by 14 surgeons that participated in a large national society symposium, and excluded 234 operated by the anterosuperior approach, 42 operated for rheumatoid arthritis, fractures, instability or post traumatic sequalae, and eight that had adjuvant latissimus dorsi tendon transfer (LDTT). This left 632 RSAs, in which the subscapularis was detached in 594, and repaired after detachment in 495. Patients completed pre- and postoperative Constant Score and postoperative Subjective Shoulder Value (SSV). Active forward elevation, active external rotation (ER), and active internal rotation (IR) were recorded pre- and postoperatively. Complications following RSA that required conservative treatment, reoperation without implant removal, as well as reoperation with implant removal were recorded.

RESULTS

Of the initial cohort of 632 shoulders, 120 (19%) were lost to follow-up, 12 (2%) died due to causes unrelated to RSA, and 26 (4%) were revised with implant removal. Of the remaining 474 shoulders, 259 (55%) had a functional repaired subscapularis (Group FR), 59 (12%) had a non-functional repaired subscapularis (Group nFR), whereas 68 (14%) had a not repaired subscapularis (Group nR). Comparison of patient demographics revealed no significant differences among the three groups. Postoperative Constant Score (p=0.031) and SSV (p=0.016) were significantly different among the three groups, but effect sizes were small and not clinically relevant. Differences in postoperative ER as well as postoperative IR were not significant among the three groups: 91 (35%) gained functional IR in Group FR, 11 (19%) in Group nFR, and 13 (19%) in Group nR. Three shoulders (1.2%) reported subjective instability and 1 (0.4%) dislocated in Group FR, but none in either Groups nFR or nR.

DISCUSSION

Despite statistically significant differences in Constant Score and SSV among the three groups, the clinical relevance of these differences is negligible, so repair of functional subscapularis has little or no influence on functional outcomes. During RSA by deltopectoral approach, repair of a functional subscapularis could slightly improve internal rotation in some patients but does not compromise external rotation, forward elevation or clinical scores, while repair of a non-functional subscapularis, compared to non-repair, did not improve range of motion or clinical scores.

LEVEL OF EVIDENCE

III; retrospective comparative.

Functional and radiographic outcomes of reverse shoulder arthroplasty with a minimum follow-up of 10 years

BACKGROUND

The use of reverse shoulder arthroplasty (RSA) is becoming increasingly prevalent. However, few studies have been published reporting the long-term outcomes of RSA. This study aims to report the clinical, radiographic, and patient-reported outcomes of the Delta Xtend reverse shoulder prosthesis, performed by a single surgeon and with a minimum follow-up of 10 years.

METHODS

All RSA procedures performed between 2005 and 2012 were identified. Patients were contacted and invited for a follow-up visit including clinical assessment, radiographs, and patient-reported outcome measures. Patients with a follow-up of less than 10 years were excluded. The revision-free implant survival was calculated at 10 years. Between 2005 and 2012, 119 procedures in 116 patients meeting inclusion criteria were identified. Of these patients, 35 were deceased before reaching the 10-year follow-up and 23 could not be reached. In total, 63 RSAs could be included in 61 patients (response rate: 75%). The median follow-up was 11.7 years (interquartile range [IQR]: 10.5-13.2).

RESULTS

Of the 61 patients, 7 patients underwent a revision after a median of 3 years (IQR: 0.2-9.8) during the total follow-up period. The 10-year implant survival was 94% (95% confidence interval: 84-98). At final follow-up, the median anterior elevation was 135° (IQR: 130°-160°), the median abduction was 120° (IQR: 100°-135°), and the median level reached with internal rotation was L5 (IQR: sacrum-L5). The median Auto-Constant score was 68 (IQR: 53-78), the median Subjective Shoulder Value was 80 (IQR: 70-93), and the median pain score was 0.2/10 (IQR: 0-2). In total, radiographs could be obtained in 25 patients (40%). Scapular notching occurred in 10 patients (40%), which was classified as Sirveaux-Nerot grade IV in 3 patients (12%). Ossification occurred in 10 patients (40%), and stress shielding in 2 patients (8%). Radiolucencies were observed around the humeral component in 24 patients (96%) and around the glenoid component in 13 patients (52%).

CONCLUSION

The long-term results of RSA with a Delta Xtend prosthesis are favorable, with long-term improvement in range of motion and patient-reported outcome measures, and a satisfactory implant survival rate. Interestingly, the radiographical analysis showed high prevalence of signs associated with loosening, which did not seem to translate to high complication rates or inferior results.

Predictive factors influencing internal rotation following reverse total shoulder arthroplasty

BACKGROUND

Reverse total shoulder arthroplasty (RTSA) is increasingly used as a treatment modality for various pathologies. The purpose of this review is to identify preoperative risk factors associated with loss of internal rotation (IR) after RTSA.

METHODS

A systematic review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Ovid MEDLINE, Ovid Embase, and Scopus were queried. The inclusion criteria were as follows: articles in English language, minimum 1-year follow-up postoperatively, study published after 2012, a minimum of 10 patients in a series, RTSA surgery for any indication, and explicitly reported IR. The exclusion criteria were as follows: articles whose full text was unavailable or that were unable to be translated to English language, a follow-up of less than 1 year, case reports or series of less than 10 cases, review articles, studies in which tendon transfers were performed at the time of surgery, procedures that were not RTSA, and studies in which the range of motion in IR was not reported.

RESULTS

The search yielded 3792 titles, and 1497 duplicate records were removed before screening. Ultimately, 16 studies met the inclusion criteria with a total of 5124 patients who underwent RTSA. Three studies found that poor preoperative functional IR served as a significant risk factor for poor postoperative IR. Eight studies addressed the impact of subscapularis, with 4 reporting no difference in IR based on subscapularis repair and 4 reporting significant improvements with subscapularis repair. Among studies with sufficient power, BMI was found to be inversely correlated with degree of IR after RTSA. Preoperative opioid use was found to negatively affect IR. Other studies showed that glenoid retroversion, component lateralization, and individualized component positioning affected postoperative IR.

CONCLUSIONS

This study found that preoperative IR, individualized implant version, preoperative opioid use, increased body mass index and increased glenoid lateralization were all found to have a significant impact on IR after RTSA. Studies that analyzed the impact of subscapularis repair reported conflicting results.

Reverse shoulder arthroplasty with a 155° neck-shaft angle inlay implant design without reattachment of the subscapularis tendon results in satisfactory functional internal rotation and no instability: a cohort study

BACKGROUND

The aim of this study was to use the Activities of Daily Living which require Internal Rotation (ADLIR) questionnaire to assess the functional internal rotation in patients who had undergone reverse shoulder arthroplasty (RSA) without reattachment of the subscapularis (SSc) tendon at a minimum follow-up of 2 years. The secondary aim was to report the objective range of motion (ROM) and the rate of postoperative instability.

MATERIALS AND METHODS

All consecutive primary RSA procedures without reattachment of the SSc tendon that were performed using a Delta Xtend prosthesis (an inlay system with a 155° neck-shaft angle) between January 2015 and December 2020 were identified to ensure a minimum follow-up of 2 years. Patients were contacted and requested to fill in several questionnaires, including the ADLIR and Auto-Constant scores.

RESULTS

In total, 210 patients met the inclusion criteria; among those patients, 187 could be contacted and 151 completed questionnaires (response rate: 81%). The SSc tendon was fully detached without repair in all cases, and a superolateral approach was used in 130 (86%) cases. The median follow-up was 4.5 years (range: 2.0-7.6). At final follow-up, the mean ADLIR score was 88/100 (interquartile range (IQR): 81-96). The median level reached in internal rotation was the 3rd lumbar vertebra (IQR: lumbosacral region-12th thoracic vertebra). Of the 210 eligible patients, one required a revision for a dislocation within the first month after primary surgery. With regards to regression analysis with ADLIR score as the outcome, none of the factors were associated with the ADLIR score, although age and smoking approached significance (0.0677 and 0.0594, respectively). None of the explanatory variables were associated with ROM in internal rotation (p > 0.05).

CONCLUSIONS

This study demonstrates that satisfactory ADLIR scores and internal rotation ROM were obtained at mid-term follow-up after RSA leaving the SSc detached. Leaving the SSc detached also did not lead to high instability rates; only one out of 210 prostheses was revised for dislocation within the first month after primary surgery.

LEVEL OF EVIDENCE III

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.

Discordance between patient-reported and objectively measured internal rotation after reverse shoulder arthroplasty

BACKGROUND

Patient satisfaction after reverse shoulder arthroplasty (RSA) partly relies on restoring functional internal rotation (IR). Although postoperative assessment of IR includes objective appraisal by the surgeon and subjective report from the patient, these evaluations may not vary together uniformly. We assessed the relationship between objective, surgeon-reported assessments of IR and subjective, patient-reported ability to perform IR-related activities of daily living (IRADLs).

METHODS

Our institutional shoulder arthroplasty database was queried for patients undergoing primary RSA with a medialized-glenoid lateralized-humerus design between 2007-2019 and minimum 2-year follow-up. Patients who were wheelchair bound or had a preoperative diagnosis of infection, fracture, and tumor were excluded. Objective IR was measured to the highest vertebral level reached with the thumb. Subjective IR was reported based on patients' rating (normal, slightly difficult, very difficult, or unable) of their ability to perform 4 IRADLs (tuck in shirt with hand behind back, wash back or fasten bra, personal hygiene, and remove object from back pocket). Objective IR was assessed preoperatively and at latest follow-up and reported as median and interquartile ranges.

RESULTS

A total of 443 patients were included (52% female) at a mean follow-up of 4.4 ± 2.3 years. Objective IR improved pre- to postoperatively from L4-L5 (buttocks to L1-L3) to L1-L3 (L4-L5 to T8-T12) (P < .001). Preoperatively reported IRADLs of "very difficult" or "unable" significantly decreased postoperatively for all IRADLs (P ≤ .004) except those unable to perform personal hygiene (3.2% vs. 1.8%, P > .99). The proportions of patients who improved, maintained, and lost objective and subjective IR was similar between IRADLs; 14%-20% improved objective IR but lost or maintained subjective IR and 19%-21% lost or maintained the same objective IR but improved subjective IR depending on the specific IRADL assessed. When ability to perform IRADLs improved postoperatively, objective IR also increased (P < .001). In contrast, when subjective IRADLs worsened postoperatively, objective IR did not significantly worsen for 2 of 4 IRADLs assessed. When examining patients who reported no change in ability to perform IRADLs pre- vs. postoperatively, statistically significant increases in objective IR were found for 3 of 4 IRADLs assessed.

CONCLUSIONS

Objective improvement in IR parallels improvements in subjective functional gains uniformly. However, in patients with worse or equivalent IR, the ability to perform IRADLs postoperatively does not uniformly correlate with objective IR. When attempting to elucidate how surgeons can ensure patients will have sufficient IR after RSA, future investigations may need to use patient-reported ability to perform IRADLs as the primary outcome measure rather than objective measures of IR.

High and low performers in internal rotation after reverse total shoulder arthroplasty: a biplane fluoroscopic study

BACKGROUND

Internal rotation in adduction is often limited after reverse total shoulder arthroplasty (rTSA), but the origins of this functional deficit are unclear. Few studies have directly compared individuals who can and cannot perform internal rotation in adduction. Little data on underlying 3D humerothoracic, scapulothoracic, and glenohumeral joint relationships in these patients are available.

METHODS

Individuals >1-year postoperative to rTSA were imaged with biplane fluoroscopy in resting neutral and internal rotation in adduction poses. Subjects could either perform internal rotation in adduction with their hand at T12 or higher (high, N = 7), or below the hip pocket (low, N = 8). Demographics, the American Shoulder and Elbow Surgeons score, Simple Shoulder Test, and scapular notching grade were recorded. Joint orientation angles were derived from model-based markerless tracking of the scapula and humerus relative to the torso. The 3D implant models were aligned to preoperative computed tomography models to evaluate bone-implant impingement.

RESULTS

The Simple Shoulder Test was highest in the high group (11 ± 1 vs. 9 ± 2, P = .019). Two subjects per group had scapular notching (grades 1 and 2), and 3 high group and 4 low group subjects had impingement below the glenoid. In the neutral pose, the scapula had 7° more upward rotation in the high group (P = .100), and the low group demonstrated 9° more posterior tilt (P = .017) and 14° more glenohumeral elevation (P = .047). In the internal rotation pose, axial rotation was >45° higher in the high group (P ≤ .008) and the low group again had 11° more glenohumeral elevation (P = .058). Large rotational differences within subject groups arose from a combination of differences in the resting neutral and maximum internal rotation in adduction poses, not only the terminal arm position.

CONCLUSIONS

Individuals who were able to perform high internal rotation in adduction after rTSA demonstrated differences in joint orientation and anatomic biases versus patients with low internal rotation. The high rotation group had 7° more resting scapular upward rotation and used a 15°-30° change in scapular tilt to perform internal rotation in adduction versus patients in the low group. The combination of altered resting scapular posture and restricted scapulothoracic range of motion could prohibit glenohumeral rotation required to reach internal rotation in adduction. In addition, inter-patient variation in humeral torsion may contribute substantially to postoperative internal rotation differences. These data point toward modifiable implant design and placement factors, as well as foci for physical therapy to strengthen and mobilize the scapula and glenohumeral joint in response to rTSA surgery.