Fracture of the patella after total knee arthroplasty.

Patellar fracture after knee arthroplasty was found in 11 patients (12 knees) during a 15-year period. Causes of this fracture include trauma, technical factors, and biophysical factors. The incidence of this infrequent complication was significantly increased after patella resurfacing and revision arthroplasty. Minimally displaced, non-comminuted fractures were immobilized, whereas displaced, comminuted fractures with loose patellar prostheses were treated operatively. At a mean follow-up period of 28 months, the average knee score was 75 points. The average arc of motion was 87 degrees, and six of the 11 patients have returned to their prefracture functional level. Treatment should be individualized on the basis of fracture displacement, comminution, and button fixation.