Patellar stress fracture: a complication of knee joint arthroplasty without patellar resurfacing.

A case of patellar stress fracture after total knee arthroplasty in a man with gout and previous osteonecrosis of the tali is reported. The combination of fat pad excision and lateral release causing disruption to the patellar blood supply during primary total knee arthroplasty resulted in the development of a patellar fracture. Avascular necrosis, caused by gout, may form part of the pathogenesis.