Clinical performance of lateralized versus non-lateralized reverse shoulder arthroplasty: a prospective randomized study

Abstract

Background: Reverse shoulder arthroplasty (RSA) is an established therapeutic option in the treatment of cuff tear arthropathy (CTA). Recent studies have described a positive effect of lateralization of the center of rotation, especially on postoperative rotational function. The goal of this study is to compare the outcome of non-lateralized versus lateralized RSA with particular regard to rotational function in patients with CTA.

Methods: Thirty-four patients underwent implantation of RSA either with lateralization (n = 17) or without lateralization (n = 17) by use of a 1-cm autologous bone graft ("bony increased offset") of the humeral head for CTA. Clinical outcomes were measured with the Constant score; the Disabilities of the Arm, Shoulder and Hand score; and the Activities of Daily Living Requiring External Rotation score, as well as measurement of external rotation and determination of the external rotation lag sign with the arm at the side and at 90° of abduction, at 1 year postoperatively and at final follow-up. Computed tomography scan evaluation was performed in all patients preoperatively and at 1 year postoperatively to assess preoperative fatty infiltration of the rotator cuff and bony integration of the graft postoperatively.

Results: At final follow-up, all patients showed significantly increased functional results. There were no significant differences in the evaluated parameters. If patients with degenerative changes of the teres minor were excluded, the lateralized group showed significantly increased external rotation. Bony integration of the graft could be verified on postoperative computed tomography scans in all patients.

Conclusion: RSA with bony lateralization shows a trend toward improved external rotation in lateralized RSA, with a statistically significant improvement in external rotation in patients with an intact teres minor.

Keywords: BIO-RSA; Reverse shoulder arthroplasty; external rotation; lateralization.