Stemless total shoulder arthroplasty using a novel multiplanar osteotomy and elliptical humeral head results in both improved early range of motion and radiographic center of rotation compared with standard total shoulder arthroplasty.

Abstract

Restoration of the native glenohumeral anatomy is an important consideration in obtaining optimal range of motion (ROM) after anatomic total shoulder arthroplasty (TSA). Recently, a new stemless TSA system has been developed that uses both a multiplanar osteotomy (MPO), to improve the surgeon's ability to restore humeral center of rotation (COR), and an elliptical humeral head to improve ROM. The purpose of our study was to compare the difference in early postoperative ROM and restoration of radiographic COR, between this stemless TSA and standard stemmed TSAs. This was a retrospective review of 50 consecutive primary TSAs performed by a single surgeon for glenohumeral osteoarthritis. The initial cohort underwent TSA with a standard stemmed humeral component with a circular humeral head (n=25), whereas the subsequent cohort underwent stemless TSA using an MPO and an elliptical humeral head (n=25). Postoperative data collection included active shoulder ROM as measured by goniometer, complications or revision surgery, and measurements of radiographic COR. Patients were assessed at 6 weeks, 12 weeks, 6 months, and 12 months after surgery. Change in COR was determined on postoperative radiographs by 2 fellowship-trained surgeons on 2 separate occasions. Intra- and interrater reliability were computed using intraclass correlation coefficients. For both mean forward flexion (FF) and external rotation (ER), there was greater ROM in the MPO-elliptical group at all time points, which was statistically significant. Mean change in FF favored the MPO group at 6 and 12 weeks and was statistically significant and above the minimal clinically important difference (MCID): 6 weeks, standard -15.8° vs. MPO 8.4° (P=.004); 12 weeks, standard 6.4° vs. MPO 29.2° (P=.001). Mean change in ER favored the MPO group at 6 weeks and was statistically significant: standard 5.4° vs. MPO 14.0° (P=.02). There were no revision surgeries in either group. Average change in COR was 2.7 mm in the standard group and 1.8 mm in the MPO-elliptical group, which was statistically significant (P<.001). Number of patients with >3 mm of difference in COR was 10 (40%) in the standard group and 1 (5%) in the MPO-elliptical group, which was statistically significant (P=.002). Average intraclass correlation coefficient was 0.75, indicating good reliability within and between surgeon measurements. The use of a multiplanar osteotomy and elliptical humeral head was associated with improved early range of motion and better reproduction of the radiographic COR compared with standard stemmed TSA.