Clinical outcomes of anatomic vs. reverse total shoulder arthroplasty in primary osteoarthritis with preoperative rotational stiffness and an intact rotator cuff: a case control study.

BACKGROUND: Reverse total shoulder arthroplasty (rTSA) has begun to challenge the place of anatomic total shoulder arthroplasty (aTSA) as a primary procedure for certain indications. One purported benefit of aTSA is improved postoperative range of motion (ROM) compared to rTSA especially in internal rotation; however, it is unclear whether aTSA can provide patients with significant preoperative stiffness superior ROM compared to rTSA. Our purpose was to compare clinical outcomes of aTSA and rTSA performed in stiff vs. non-stiff shoulders for rotator cuff intact (RCI) glenohumeral osteoarthritis (GHOA). METHODS: A retrospective review of an international shoulder arthroplasty database identified 1608 aTSAs and 600 rTSAs performed for RCI GHOA with minimum 2-year follow-up. Defining preoperative stiffness as ≤ 0° of passive external rotation (ER), we matched: (1) stiff aTSAs (n = 257) 1:3 to non-stiff aTSAs, (2) stiff rTSAs (n = 87) 1:3 to non-stiff rTSAs, and (3) stiff rTSAs (n = 87) 1:1 to stiff aTSAs. We compared ROM, outcome scores, and the rate of complications and revision surgery at latest follow-up. RESULTS: Despite stiff aTSAs having poorer preoperative ROM and functional outcome scores for all measures assessed (P < .001 for all), only poorer postoperative active abduction (113 ± 27° vs. 128 ± 35°; P < .001), active ER (39 ± 18° vs. 50 ± 20°; P < .001), and passive ER (45 ± 17° vs. 56 ± 18°; P < .001) persisted postoperatively compared to the non-stiff cohort. Similarly, stiff rTSAs had poorer preoperative ROM and functional outcome scores for all measures assessed compared to non-stiff rTSAs (P ≤ .044), but only poorer active abduction (108 ± 24° vs. 128 ± 29°, P < .001), active ER (28 ± 17° vs. 42 ± 17°, P < .001), and passive ER (36 ± 15° vs. 48 ± 17°, P < .001) persisted. When comparing stiff rTSAs to matched stiff aTSAs, no significant differences in preoperative ROM or functional outcome scores were found. However, stiff aTSAs had greater postoperative active internal rotation score (4.8 ± 1.5 vs. 4.2 ± 1.7, P = .022), active ER (40 ± 19° vs. 28 ± 17°, P < .001), and passive ER (46 ± 18° vs. 36 ± 15°, P = .001). Postoperative outcome scores were similar across all matched cohort comparisons despite motion differences. The rate of complications and need for revision surgery did not differ between any group comparisons. CONCLUSIONS: Patients with RCI GHOA who have preoperative rotational stiffness have poorer postoperative ROM compared with non-stiff patients following both aTSA and rTSA, but similar functional outcome scores. Notably, preoperative limitations in passive ER do not appear to be a limitation to utilizing aTSA. Indeed, patients with limited preoperative ER treated with aTSA had greater postoperative internal rotation and ER compared to those treated with rTSA.

High intraoperative accuracy and low complication rate of computer-assisted navigation of the glenoid in total shoulder arthroplasty.

BACKGROUND: Preoperative planning software with intraoperative guidance technology is increasingly being used to manage complex glenoid deformity in anatomic total shoulder arthroplasty (TSA) and reverse TSA. The aim of this study was to review the intraoperative efficacy and complications of computer-assisted navigation (CAN) surgery for the treatment of glenoid deformity in TSA. METHODS: We performed a retrospective review of all TSAs implanted using a single computer navigation shoulder system. All patients underwent preoperative planning with computed tomography-based preoperative planning software. The starting point on the glenoid and the final version and inclination of the central post (cage) of the glenoid component were reviewed on the intraoperative navigation guidance report and compared with these parameters on the preoperative plan for each patient. The intraoperative accuracy of CAN for glenoid positioning was determined by the deviation of the starting point and final position of the central cage drill in the glenoid compared with the preoperative plan. Data regarding intraoperative complications and the number of times the navigation system was abandoned intraoperatively were collected. RESULTS: A total of 16,723 anatomic TSAs and reverse TSAs performed worldwide with the aforementioned navigation system were included in this review. In 16,368 cases (98%), every step of the navigation procedure was completed without abandoning use of the system intraoperatively. There was minimal deviation in the intraoperative execution of the preoperative plan with respect to version (0.6° ± 1.96°), inclination (0.2° ± 2.04°), and the starting point on the glenoid face (1.90 ± 1.2 mm). In this cohort, 9 coracoid fractures (0.05%) were reported. CONCLUSION AND DISCUSSION: This study demonstrates the safety and efficacy of CAN for glenoid implantation in TSA. Future studies should focus on assessing the impact of CAN on the longevity and survival of glenoid components and improving the cost-effectiveness of this technology.

Exactech Equinoxe anatomic versus reverse total shoulder arthroplasty for primary osteoarthritis: case controlled comparisons using the machine learning-derived Shoulder Arthroplasty Smart score.

BACKGROUND: The role of reverse total shoulder arthroplasty (rTSA) for glenohumeral osteoarthritis (GHOA) with an intact rotator cuff remains unclear with prior investigations demonstrating similar patient-reported outcome measures (PROMs) to anatomic total shoulder arthroplasty (aTSA). However, legacy PROMs are subject to skewed distributions with many patients achieving the maximum possible score (ceiling scores). We evaluated a cohort of primary rTSAs performed for GHOA with an intact rotator cuff compared with a case-matched cohort of aTSAs using the Shoulder Arthroplasty Smart (SAS) score, a machine learning-derived outcome measure that eliminates the ceiling effect. METHODS: A retrospective review of an international shoulder arthroplasty database was performed between 2001 and 2020. Patients undergoing rTSA for rotator cuff intact GHOA (n = 367) were matched 1:1 with aTSA controls (n = 367) with a minimum of 2-year follow-up. Assessed variables included patient demographics, range of motion, American Shoulder Elbow Surgeons score (ASES), Constant score, Simple Shoulder Test (SST), and the SAS score. RESULTS: Preoperatively, the SAS (49.0 vs. 45.2; P < .001), SST (4.7 vs. 4.1; P = .002), and Constant score (42.5 ± 15.3 vs. 38.1 ± 14.2; P < .001) were greater in aTSA vs. rTSA. Similarly, the SAS score (82.3 vs. 77.6; P < .001) and SST score (10.8 vs. 10.3; P = .003) remained greater in aTSA postoperatively. In contrast, no differences in the ASES (P = .103) or Constant scores (P = .108) were found between aTSA and rTSA patients postoperatively. Improvement preoperatively to postoperatively did not differ between aTSA and rTSA patients when assessed using the SAS (P = .257), ASES (P = .888), or SST scores (P = .510). However, a higher rate of improvement in the Constant score (35.0 vs. 31.8; P = .022) was observed in rTSA compared with aTSA. Higher rates of complications (5.4% vs. 1.6%; P = .008) and revision surgery (4.1% vs. 0.5%; P = .002) were observed in aTSA compared with rTSA. CONCLUSIONS: Patients undergoing shoulder arthroplasty for rotator cuff intact GHOA experienced higher rates of complications and revisions in aTSA compared with rTSA, but similar levels of clinical improvement between implants when evaluated using a validated outcome score without a ceiling effect. Unlike the ASES and SST scores that are limited by ceiling effects, a higher mean postoperative SAS score after aTSA was observed, but preoperative to postoperative SAS differences were similar after rTSA.

Two-year clinical outcomes and complication rates in anatomic and reverse shoulder arthroplasty implanted with Exactech GPS intraoperative navigation.

INTRODUCTION: We compared the 2-year clinical outcomes of both anatomic and reverse total shoulder arthroplasty (ATSA and RTSA) using intraoperative navigation compared to traditional positioning techniques. We also examined the effect of glenoid implant retroversion on clinical outcomes. HYPOTHESIS: In both ATSA and RTSA, computer navigation would be associated with equal or better outcomes with fewer complications. Final glenoid version and degree of correction would not show outcome differences. MATERIAL AND METHODS: A total of 216 ATSAs and 533 RTSAs were performed using preoperative planning and intraoperative navigation with a minimum of 2-year follow-up. Matched cohorts (2:1) for age, gender, and follow-up for cases without intraoperative navigation were compared using all standard shoulder arthroplasty clinical outcome metrics. Two subanalyses were performed on navigated cases comparing glenoids positioned greater or less than 10° of retroversion and glenoids corrected more or less than 15°. RESULTS: For ASTA, no statistical differences were found between the navigated and non-navigated cohorts for postoperative complications, glenoid implant loosening, or revision rate. No significant differences were seen in any of the ATSA outcome metrics besides higher internal and external rotation in the navigated cohort. For RTSA, the navigated cohort showed an ARR of 1.7% (95% CI 0%, 3.4%) for postoperative complications and 0.7% (95% CI 0.1%, 1.2%) for dislocations. No difference was found in the revision rate, glenoid implant loosening, acromial stress fracture rates, or scapular notching. Navigated RTSA patients demonstrated significant improvements over non-navigated patients in internal rotation, external rotation, maximum lifting weight, the Simple Shoulder Test (SST), Constant, and Shoulder Arthroplasty Smart (SAS) scores. For the navigated subcohorts, ATSA cases with a higher degree of final retroversion showed significant improvement in pain, Constant, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), SST, University of California-Los Angeles shoulder score (UCLA), and Shoulder Pain and Disability Index (SPADI) scores. No significant differences were found in the RTSA subcohort. Higher degrees of version correction showed improvement in external rotation, SST, and Constant scores for ATSA and forward elevation, internal rotation, pain, SST, Constant, ASES, UCLA, SPADI, and SAS scores for RTSA. CONCLUSION: The use of intraoperative navigation shoulder arthroplasty is safe, produces at least equally good outcomes at 2 years as standard instrumentation does without any increased risk of complications. The effect of final implant position above or below 10° of glenoid retroversion and correction more or less than 15° does not negatively impact outcomes.

Two-year minimum survivorship and radiographic analysis of a pressfit short humeral stem for total shoulder arthroplasty.

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.

Short-term radiographic analysis of a stemless humeral component for anatomic total shoulder arthroplasty.

Background: Standard stemmed humeral implants have traditionally been utilized for total shoulder arthroplasty (TSA) with a recent trend to implant smaller stems including short and stemless humeral designs. However, the rate of stress shielding after stemless TSA has not been primarily studied. Therefore, the objective of this study is to report the short-term survivorship and radiographic analysis of a stemless humeral implant. Methods: A retrospective cohort review of a prospectively collected, multicenter database for patients undergoing total shoulder arthroplasty with a stemless humeral design (Equinoxe Stemless; Exactech, Inc., Gainesville, FL, USA) with a minimum of 2 years clinical and radiographic follow-up was performed. The primary outcomes were to report the location and rate of stress shielding from a radiographic analysis of the humeral stem. Additionally, the revision rate of the humeral stem is reported. The secondary outcomes included ASES scores, visual analog scale (VAS) pain scores, and range of motion (ROM). Radiographs (anterior-posterior/Grashey and axillary) were reviewed blindly by two fellowship trained shoulder surgeons. Radiographic analysis included stress shielding (partial or complete cortical resorption) and subsidence or shift in component position. Results: Fifty four patients were included in this study with an average follow-up of 27 months (range 24-32 months). The average age of this cohort was 65 years (range 57-73 years) with 23 patients (43%) being female. Stress shielding was observed in 4 patients (7%) with the medial calcar being the most common location of stress shielding. Three of the 4 patients (75%) had evidence of partial resorption while 1 patient (25%) had evidence of complete resorption. No humeral component shift or subsidence was observed. There were no revisions due to humeral component complications. There was 1 revision surgery for aseptic glenoid loosening. A significant improvement for all clinical outcome measures was seen including with respect to VAS pain, which improved from 6.2 to 1.8 (P < .05), ASES, which improved from 38.2 to 81.8 (P < .05), and ROM which forward flexion improved from 120 degrees to 153 degrees (P < .05) and external rotation improved from 29 degrees to 49 degrees (P < .05). Discussion: This ongoing study demonstrates a low rate of stress shielding for a stemless design humeral implant at short-term follow-up without any revision surgery due to humeral component complications. Longer term radiographic and clinical analysis with this cohort will be needed to confirm these findings and theoretical benefits for future revision surgeries.

The over-the-top subscapularis repair in reverse shoulder arthroplasty: biomechanical evaluation of a novel technique.

BACKGROUND: We evaluate the effect of repairing the upper subscapularis tendon at an alternative location on the anterior greater tuberosity above the center of rotation using a reverse shoulder arthroplasty (RSA) muscle model. METHODS: We compared an innovative subscapularis repair on the anterior aspect of the greater tuberosity with the standard repair on the lesser tuberosity in a previously validated digital linear RSA muscle model. Standard repair vs. a new repair datasets were compared for 3 RSA designs. Each model was run through humeral abduction from 0° to 140° in 2.5° increments; the resulting moment arm measurements (model of tendon efficiency) were recorded in millimeters for 3 sections (superior, middle, inferior). An isolated upper two-thirds subscapularis repair to the anterior greater tuberosity was also evaluated (the over-the-top repair). RESULTS: The new over-the-top subscapularis repair significantly increased the abduction moment arm lengths in the superior, middle, and inferior subscapularis components compared with the standard repair to the lesser tuberosity at all levels of glenohumeral abduction and for all 3 RSA designs. Repair of the upper two-thirds of the subscapularis to the new location was an abductor at a much lower level of abduction compared with the native subscapularis repair. CONCLUSION: By repairing the upper subscapularis tendon above the center of rotation (over-the-top repair) in an RSA muscle model, the subscapularis has an improved movement arm and functions as an abductor through a greater range of motion that may result in clinically increased muscle efficiency and improved strength.