Effects of acquired glenoid bone defects on surgical technique and clinical outcomes in reverse shoulder arthroplasty.

BACKGROUND Reverse total shoulder arthroplasty is the accepted method of treatment for selected shoulder disorders. The purpose of this study was to compare primary reverse shoulder arthroplasty surgical techniques as well as clinical and radiographic outcomes in patients with acquired glenoid bone defects and in those with normal glenoid morphology. METHODS Preoperative three-dimensional computed tomography scans were performed on 216 shoulders in 211 patients undergoing primary reverse shoulder arthroplasty between 2004 and 2007. The glenoids were classified as normal or abnormal on the basis of preoperative radiographs and three-dimensional reconstructions of the scapula. One hundred and forty-three shoulders had been followed for two years. There were eighty-seven normal and fifty-six abnormal glenoids. The surgical techniques that were compared included bone-grafting and glenosphere selection. The clinical outcomes for the two groups were compared with respect to the American Shoulder and Elbow Surgeons score. RESULTS Surgical technique differed between the groups. All fifty-six glenoids with acquired bone defects had center screw placement along an alternative (scapular spine) centerline. A bone graft was used in twenty-two shoulders with acquired glenoid bone defects compared with none of those with normal glenoid morphology (p = 0.016). Shoulders with glenoid defects were treated with larger glenospheres (36 or 40 mm) more often than those with normal glenoids (p < 0.001). No significant difference was detected between the groups with regard to the preoperative or postoperative American Shoulder and Elbow Surgeons scores. Radiographs did not demonstrate failure or resorption of a glenoid bone graft when present. All outcomes improved significantly postoperatively. There were five complications, and one patient was unsatisfied with the result. CONCLUSIONS Glenoid bone defects, when managed with an alteration of surgical technique, including bone-grafting when indicated, are not a contraindication to reverse total shoulder arthroplasty.