The cemented inset biconvex patella in revision knee arthroplasty

Evaluation of a cemented biconvex inset patellar component used in revision knee arthroplasty at minimum five year follow-up was undertaken. Of the initial cohort of 89 knees in 85 patients, two patellar implants were revised for aseptic loosening following a transverse fracture of the patella associated with avascular necrosis. A further four implants were judged radiographically loose. Aseptic loosening of the implant was strongly correlated with the presence of avascular necrosis radiographically. Fracture of the patellar bone remnant was associated with a radiographically measured thickness of residual patellar bone of less than 6 mm. Survivorship of the implant using aseptic revision as the endpoint was 98% at 10 years and 86% at 14 years given one late failure. We conclude that the cemented biconvex inset patellar component can give satisfactory results in revision of patellar components if avascular necrosis does not occur.