Restoration of External Rotation Following a Lateral Approach for Glenoid Bony Increased-Offset Reverse Shoulder Arthroplasty

Abstract

Background:Reverse shoulder arthroplasty (RSA) is a recognized therapeutic modality for a massive rotator cuff tear. Some authors recommend lateralization of the center of rotation by bony increased offset (BIO) of the glenoid for improvement of external rotation, while others refute its effects. RSA through the conventional deltopectoral approach sacrifices the subscapularis tendon during the approach. We hypothesized that a lateral approach (LA) for RSA, with less soft-tissue resection, would restore external rotation by allowing retensioning of the remaining rotator cuff with use of a BIO graft.Methods:We retrospectively investigated 36 nonlateralized inlay RSAs performed through a lateral approach (LA non-BIO group) and 40 inlay RSAs performed through a lateral approach with BIO (LA BIO group) for a massive rotator cuff tear. There were 5 patients with a combined loss of active elevation and external rotation (CLEER) in the LA non-BIO group and 6 in the LA BIO group. The Constant score, the UCLA (University of California Los Angeles) score, and range of motion, in particular, external rotation with the arm at 0° (ER0) and at 90° of abduction (ER90), were compared.Results:The mean ER90 in the LA BIO group improved significantly, from 45.8° ± 21.6° to 65.9° ± 15.8° (p = 0.012). Postoperative ER90 in the LA BIO group was significantly higher than in the LA non-BIO group (mean, 65.9° ± 15.8° compared with 53.0° ± 12.3°; p = 0.026). The mean ER0 for the patients with CLEER status significantly improved in the LA BIO group, from −15.8° ± 9.8° to 11.0° ± 15.6° (p = 0.0072). The mean postoperative anterior elevation, UCLA score, and Constant score in the LA BIO group and the LA non-BIO group improved significantly, but there was no difference between the 2 groups (anterior elevation: 131.5° ± 17.6° compared with 121.5° ± 14.1°, p = 0.07; UCLA: 25.5 ± 6.4 compared with 23.4 ± 5.4, p = 0.2; Constant: 74.3 ± 12.0 compared with 73.6 ± 10.1, p = 0.43).Conclusions:LA BIO-RSA was associated with a significant improvement in range of motion, particularly external rotation. Improvements in anterior elevation, the Constant score, and the UCLA score were not significantly different from those noted for LA non-BIO-RSA.Level of Evidence:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.