Tuberosity malposition and migration: reasons for poor outcomes after hemiarthroplasty for displaced fractures of the proximal humerus.
The purpose of this study was to evaluate the results of hemiarthroplasty for displaced proximal humeral fractures and to assess clinical and radiologic parameters that could explain unsatisfactory results. Sixty-six consecutive patients (45 women and 21 men) with a mean age of 66 years (range, 31-85 years) were followed up postoperatively for a mean of 27 months (range, 18-59 months), both clinically and radiologically. Subjectively, 29 patients were very satisfied, 9 were satisfied, and 28 were unsatisfied. Postoperative active elevation averaged 101 degrees +/- 33 degrees, external rotation averaged 18 degrees +/- 15 degrees, and internal rotation averaged the L3 level (+/-3 vertebrae). The absolute Constant score averaged 56 of 100 points (range, 20-95 points). Initial tuberosity malposition was present in 18 patients (27%). Tuberosity detachment and migration were noted in 15 patients (23%). Tuberosity migration could be observed after initial tuberosity malpositioning, as well as after initial correct positioning. Final tuberosity malposition occurred in 33 patients (50%) and correlated with an unsatisfactory result, superior migration of the prosthesis, stiffness or weakness, and persistent pain. Factors associated with failure of tuberosity osteosynthesis were poor initial position of the prosthesis (specifically, excessive height and/or retroversion), poor position of the greater tuberosity, and women over age 75 years (likely with osteopenic bone). Techniques to improve tuberosity osteosynthesis, including modifications to current prosthetic design and instrumentation to allow for a more anatomic reconstruction, should lead to more predictable and satisfactory results.