Femoral head allograft for glenoid bone loss in primary reverse shoulder arthroplasty: Functional and radiological outcomes

Background: Several techniques have been adopted during primary reverse shoulder arthroplasty (RSA) to manage glenoid bone defect. Among bone grafts, humeral head autograft is currently the mainstream option. However, autologous humeral heads may be unavailable or inadequate and allografts may be a viable alternative. The aim of the present study was to evaluate the functional and radiological outcomes of femoral head allografts for glenoid bone defects in primary RSA. Methods: We conducted a retrospective study with prospective data collection enrolling 20 consecutive patients who underwent RSA with femoral head allografts for glenoid bone defects. Indications for surgery were eccentric cuff tear arthropathy in 10 (50%) cases, concentric osteoarthritis in 9 (45%) cases, and fracture sequelae in one (5%) case. Each patient was evaluated preoperatively and at follow-up by X-ray and computed tomography (CT) and by assessing the range of motion (ROM) and the Constant-Murley score (CMS). A CT-based software, a patient-specific 3D model of the scapula, and patient specific instrumentation were used to shape the graft and to assess the position of K-wire for central peg. Postoperatively, CT scans were used to identify graft incorporation and resorption. Results: After a median follow-up of 26.5 months (24-38), ROM and CMS showed a statistically significant improvement (all p=0.001). The median measures of the graft were as follows: 28 mm (28-29) for diameter, 22° (10°-31°) for angle, 4 mm (2-8 mm) for minimum thickness, and 15 mm (11-21 mm) for maximum thickness. Before the surgery, the median glenoid version was 21.8° (16.5°-33.5°) for the retroverted glenoids and -13.5° (-23° to -12°) for the anteverted glenoids. At the follow-up, the median postoperative baseplate retroversion was 5.7° (2.2°- 1.5°) (p=0.001), and this value was close to the 4° retroversion planned on the preoperative CT-based software. Postoperative major complications were noted in four patients: two dislocations, one baseplate failure following a high-energy trauma, and one septic baseplate failure. Partial graft resorption without glenoid component failure was observed in three cases that did not require revision surgery. Conclusion: The femoral head allograft for glenoid bone loss in primary RSA restores shoulder function with CMS values comparable to those of sex- and age-matched healthy individuals. A high rate of incorporation of the graft and satisfactory correction of the glenoid version can be expected after surgery. The management of glenoid bone defects remains a challenging procedure, and a 15% risk of major complication must be considered.