Shoulder arthroplasty for traumatic avascular necrosis: predictors of outcome.

Posttraumatic avascular humeral head necrosis may require salvage shoulder arthroplasty in symptomatic cases. We tested the hypothesis that associated tuberosity malunion negatively influences the final clinical outcome after shoulder arthroplasty. Thirty-eight patients with posttraumatic avascular necrosis of the humeral head were followed clinically and radiographically for a minimum of 5 years (mean, 8 years; range, 5-13 years). To quantify preoperative tuberosity malunion, two novel radiographic parameters were introduced: on the anteroposterior view, the greater tuberosity offset as a measurement of lateralization of the greater tuberosity; and on the axillary view, the posterior offset to quantify the degree of widening at the intertubercular groove. At last followup, the average Constant and Murley score had improved from 27 points preoperatively to 57 points postoperatively; shoulder range of motion had increased from 40 degrees abduction to 116 degrees, flexion from 45 degrees to 120 degrees, and external rotation from 15 degrees to 39 degrees. Functional improvements and pain relief were substantial. A significant correlation was found between greater tuberosity offset and posterior offset and final clinical outcome. Preoperative near anatomic tuberosity alignment was associated with good results. The greater tuberosity offset and posterior offset are useful and reliable radiographic predictors of outcome.