Anatomic and Reverse Shoulder Arthroplasty for Management of B2 and B3 Glenoids: A Matched Cohort Analysis.

Abstract

Severe glenohumeral osteoarthritis (GHOA) with posterior glenoid erosion remains challenging to address for shoulder surgeons. While anatomic total shoulder arthroplasty (TSA) has historically been the choice treatment, reverse shoulder arthroplasty (RSA) offers an alternative option. Limited evidence exists directly comparing these two treatments in a similar patient population. The purpose of this study was to compare the clinical outcomes of patients with GHOA and Walch B2 and B3 glenoid morphologies treated with TSA and RSA. A multi-center retrospective cohort study was performed on patients with GHOA treated with primary shoulder arthroplasty and a minimum of 2-year follow-up. Preoperative computed tomography was used to determine B2 and B3 glenoid morphology as described by the modified Walch classification. Three-dimensional perioperative planning software was used to characterize glenoid retroversion and humeral subluxation. Patients were categorized based on TSA or RSA and matched 1:1 by gender, Walch classification, and age. Patient reported outcome measures (PROMs), active range of motion, presence and severity of glenoid loosening, and complications were compared. The percentage of patients that reached previously established clinically significant thresholds for minimal clinically important difference (MCID) and substantial clinical benefit (SCB) for the American Shoulder and Elbow Surgeons (ASES) scores was also comparatively assessed. Two hundred and two patients (101 per group) with GHOA and B2 or B3 glenoids were included in the 1:1 matched analysis. Mean and standard deviation of follow-up was 39 ± 18.7 months. The cohorts were well-matched with no differences in gender, age, ASA, BMI, preoperative glenoid morphology (Walch), glenoid retroversion, or posterior subluxation (P > 0.05). RSA was associated with lower postoperative VAS pain (RSA 0.5; TSA 1.2, P=0.036), however, no other clinical differences in PROMs were found. Most patients in both groups (TSA 95.0%; RSA 98.0%, P=0.436) reached MCID, and 82% of TSA patients and 90% of RSA patients reached SCB (P=0.292). No significant differences were found in overall complication rate (P=0.781) and active range of motion with exception of internal rotation being worse in RSA (RSA 2.7 and 5.2; TSA 3.9 and 6.5, P<0.001). Baseplate loosening occurred in 2 RSA cases and 29 TSA cases had glenoid radiolucencies (P<0.001) with 3 grossly loose glenoid components. Primary RSA results in largely comparable short-term outcomes compared to TSA in patients with Walch B2 or B3 glenoid morphology. Both TSA and RSA provide substantial clinical benefits to patients with significant posterior glenoid wear.