Is radiographic measurement of acromiohumeral distance on anteroposterior view after reverse shoulder arthroplasty reliable?

BackgroundReverse shoulder arthroplasty leads to arm lengthening. Different techniques have been described to determine postoperative lengthening. The purpose of this study was to evaluate the reliability of the acromiohumeral distance (AHD) in determining arm lengthening after reverse shoulder arthroplasty.MethodsAt 2 centers, 44 patients who had received an onlay design reverse shoulder arthroplasty were observed for a minimum of 6 months. Examination followed a standardized protocol including preoperative and postoperative radiographs on anteroposterior view in neutral rotation. Two orthopedic surgeons independently performed the measurements in random order.ResultsMean arm lengthening averaged 2.5 cm (range, 0.3-3.9 cm) according to AHD measurement. Significant differences in interobserver and intraobserver variability for postoperative AHD measurements were found (P < .01). The mean intrapatient difference was 0.5 cm (range, 0.02-1.5 cm).ConclusionAccording to our study, the AHD is not a reliable measurement technique to determine arm lengthening after reverse shoulder arthroplasty.