Subscapularis sparing total shoulder arthroplasty through a superolateral approach: a radiographic study

Abstract

Most anatomic total shoulder arthroplasty (ATSA) techniques release and reattach the subscapularis tendon. The risk of failed healing is a widely recognized complication. The purpose of this study was to radiographically compare a traditional deltopectoral (DP) approach and a superolateral subscapularis sparing (SSS) technique through the rotator interval. A single, independent, blinded, reviewer analyzed preoperative and postoperative radiographs of patients undergoing ATSA performed by a single surgeon. The reviewer assessed humeral head height, humeral head medial offset, humeral head diameter, head-neck angle, humeral head centering, and coracohumeral offset, and used the anatomic reconstruction index (ARI) to evaluate overall reconstruction quality. There were 70 SSS and 20 DP patients included. When comparing preoperative with postoperative differences, we found that there was no difference between groups in humeral head height (P = .19), humeral head medial offset (P = .38), and coracohumeral offset (P = .07). The DP group had a mean humeral head diameter oversizing of 1.4 mm, whereas the superolateral group had an undersizing of 2.8 mm (P < .001). The head-neck angle difference of the SSS approach was 2° greater than that found with the DP group (P < .001). The humeral head centering in the DP group was 7% displaced vs. 12% with the SSS group (P = .001) relative to the glenoid size. The ARI was 7.35 for the DP group and 6.93 for the SSS group (P = .50). Radiographic comparison of these 2 ATSA techniques identified no statistical significant difference in 4 of 7 radiographic measurements and ARI. The SSS ATSA is a reasonable approach that yields similar radiographic measurements as a traditional DP total shoulder arthroplasty approach.