BACKGROUND: The biconcave glenoid in patients with primary glenohumeral osteoarthritis represents a surgical challenge because of the associated static posterior instability of the humeral head and secondary posterior glenoid erosion. The purpose of the present study was to evaluate the clinical and radiographic results of reverse total shoulder arthroplasty for the treatment of primary osteoarthritis in patients with a biconcave glenoid without rotator cuff insufficiency.
METHODS: We performed a retrospective review of twenty-seven reverse shoulder arthroplasties that were performed from 1998 to 2009 for the treatment of primary glenohumeral osteoarthritis and biconcave glenoid. Eighty-one percent of the patients were female, and the mean age of the patients at the time of surgery was 74.1 years (range, sixty-six to eighty-two years). All patients had a preoperative computed tomography arthrogram to allow for the measurement of glenoid retroversion and humeral head subluxation. The mean preoperative retroversion was 32°, and the mean subluxation of the humeral head with respect to the scapular axis was 87%. Seventeen patients had a reverse shoulder arthroplasty without bone graft, whereas ten had an associated bone graft to compensate for posterior glenoid erosion. Clinical outcomes were evaluated with the Constant score and shoulder range of motion.
RESULTS: The mean duration of follow-up was fifty-four months (range, twenty-four to 139 months). The mean Constant score increased from 31 points preoperatively to 76 points at the time of the latest follow-up (p < 0.0001). Active forward flexion, external rotation, and internal rotation also significantly increased (p < 0.0001). Complications occurred in four patients (15%) and included early loosening of the glenoid component (one patient) and neurologic complications (three patients). No radiolucent lines were observed around the central peg or screws of the glenoid component. Grade-1 or 2 scapular notching was present in ten shoulders (37%). No recurrence of posterior instability was observed.
CONCLUSIONS: Reverse shoulder arthroplasty for the treatment of primary glenohumeral osteoarthritis in patients with a biconcave glenoid without rotator cuff insufficiency can result in excellent clinical outcomes. Reverse shoulder arthroplasty is a viable surgical option to solve both the problem of severe static posterior glenohumeral instability and severe glenoid erosion.
LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.