Clinical outcome of revision of the patellar component in total knee arthroplasty. A 2- to 7-year follow-up study.

The objectives of this study were to determine the relationship between the thickness of the residual patellar bone and the composite patella-patellar component, and the clinical outcome in patients who had undergone revision total knee arthroplasty (TKA) with a biconvex patellar component. Clinical outcome after at least a 2-year follow-up was determined using the Knee Society pain and functional scores, and radiographically, with the thicknesses of the patellar bone and composite measured in 23 knees (22 patients). The thickness of the patellar bone after preparation for a biconvex patellar component was significantly less for revised patellae (average, 5.0 mm) than the primary patellae (average, 7.9 mm; P < 0. 01). Differences in thickness between preoperative patellae, primary composites, and revision composites did not significantly affect postoperative results. There were no patellar fractures, despite the relatively thin bone remnant in the revision patients. Radiolucency was observed in 8% of the revisions. A patella with a thickness of residual bone of as little as 5 mm can provide favorable clinical results in revision TKA with restoration of the composite thickness of the patella achieved using a thick but small-diameter biconvex patellar component.