Isolated patellar component revision of total knee arthroplasty.

Forty-two knees in 41 patients required isolated patellar component revision of a total knee arthroplasty (TKA). Revision was performed for loosening in 14 knees, wear to metal backing in 13, fracture of the fixation peg in seven, dissociation of polyethylene from metal backing in two, anterior knee pain in two, patellar instability in two, and component malposition with fat pad proliferation in two. Thirty-six knees were evaluated two to eight years after patellar revision. The Hospital for Special Surgery knee scores improved from an average of 71 preoperatively to 81 postoperatively. Eighteen knees were excellent; 12, good; four, fair; and two, poor. Complications associated with patellar revision included late patellar fractures in five knees, patellar instability in three, peroneal nerve palsies in two, patellar polyethylene wear to metal backing in two, infection in one, and extensor lag in one. This seemingly straight-forward procedure is associated with a high complication rate.