All revision total knee arthroplasties for failure of a metal-backed patellar component during a 4-year period were reviewed. Twenty-five revisions, representing six designs, were performed in 24 patients. The failure mode included wear or fragmentation of the patellar polyethylene in 20 knees, polyethylene separation from the metal baseplate in 3, and metal peg-baseplate fracture in 2. Time to revision averaged 3.4 years. Signs and symptoms heralding failure included anterior knee pain, patellofemoral crepitus and knee synovitis or swelling; 17 knees exhibited all of these. In 20 knees, technical errors related to the patella were evident on pre-revision radiographs. Only patellar revision was required in 13 knees, replacement of all three components in 8, and patellar plus tibial insert revision in 4. The multiple designs involved suggest a generic problem that is design dependent but influenced by surgical technique.