Impaction grafting improves the fit of uncemented humeral arthroplasty

This study tested the hypothesis that the excellence of the fit between a humeral prosthesis and the humerus can be optimized by impaction grafting with cancellous bone. Ten paired human humeri were prepared for insertion of a humeral implant by a standard surgical technique. One humerus from each pair was randomized to receive a 10-mm humeral component with cancellous impaction autografting, whereas the other was inserted without grafting. After insertion of a polymethylmethacrylate model of the prosthesis, computed tomography scans were obtained with 3-mm sections and the void areas of each section measured by use of NIH Image. The data demonstrate that cancellous impaction grafting significantly reduces the void between the prosthesis and the humerus (P <.001). The effect was most marked in the proximal and middle thirds of the implant. We conclude that cancellous impaction grafting is an effective method for improving the quality of fit between the humerus and the proximal two thirds of the humeral prosthesis.