Total shoulder arthroplasty with nonspherical humeral head and inlay glenoid replacement: clinical results comparing concentric and nonconcentric glenoid stages in primary shoulder arthritis

BACKGROUND: Glenoid morphology can influence the outcomes of total shoulder arthroplasty. This study examines the results of a new technique according to preoperative glenoid staging. We hypothesized that there would be no statistically significant difference in outcomes between Levine concentric (Walch A) and Levine nonconcentric (Walch B) glenoids treated for primary glenohumeral arthritis using nonspherical humeral head and inlay glenoid replacement. METHODS: This retrospective case series included 31 shoulders in 29 patients (25 male, 4 female), with an average age of 58.5 years. Outcomes included the Penn Shoulder Score (PSS), visual analog scale for pain (VAS-Pain), range of motion, radiographic analysis, and complications. Inclusion criteria were primary glenohumeral arthritis, intact rotator cuff, and no prior open shoulder surgeries. RESULTS: Mean follow-up was 42.6 months (range, 24-74 months). The study included 7 concentric and 24 nonconcentric glenoids. Outcomes comparison showed no statistically significant differences in PSS domains including Pain (P = .92), Function (P = .98), Satisfaction (P = .89), and Total (P = .98); forward flexion (P = .78); external rotation (P = .64); and VAS-Pain (P = 0.12). At the last follow-up, the mean PSS Pain was 25.3/30, Function 52.7/60, Satisfaction 8.4/10, and Total 87.0/100. The mean forward flexion was 167.3°, external rotation 56.6°, and VAS-Pain 0.9. There were no signs of periprosthetic fracture, component loosening, osteolysis, and hardware failure, and no revisions or 90-day rehospitalizations were required. One patient was prophylactically treated with oral antibiotics for a history of prior infection and 1 patient required a later open biceps tenodesis after a traumatic proximal biceps rupture postoperatively. CONCLUSION: Nonspherical shoulder arthroplasty with inlay glenoid replacement demonstrated excellent clinical benefits for both concentric and nonconcentric glenoids. The technique appears to be a promising option for glenohumeral arthritis even in the presence of posterior glenoid erosion.