A classification-based approach to the patella in revision total knee arthroplasty

Background There is a paucity of data to guide management of the patella in revision total knee arthroplasty (RTKA). The purpose of this study was to review our experience with patellar management in RTKA. Methods We retrospectively reviewed 422 consecutive RTKAs at a minimum of 2 years (mean, 42 months). Patellar management was guided by a classification that considered stability, size, and position of the implanted patellar component, thickness/quality of remaining bone stock, and extensor mechanism competence. Results Management in 304 aseptic revisions included retention of a well-fixed component in 212 (69.7%) and revision using an all-polyethylene component in 46 (15.1%). Patella-related complications included 5 extensor mechanism ruptures (1.6%), 3 cases of patellar maltracking (1.0%), and 2 periprosthetic patellar fractures (0.7%). Of 118 2-stage revisions for infection, an all-polyethylene component was used in 88 (74.6%), patelloplasty in 20 (16.9%), and patellectomy in 7 (5.9%). Patella-related complications included 4 cases of patellar maltracking (3.4%), 3 extensor mechanism ruptures (2.5%), and 1 periprosthetic patellar fracture (0.8%). Conclusions Septic revisions required concomitant lateral releases more frequently (38.1% vs 10.9%; P <.02) but had a similar rate of patellar complications (6.8% vs 3.3%; P =.40). No cases required rerevision specifically for failure of the patellar component. Patients who had a patelloplasty had worse postoperative Knee Society functional scores than those with a retained or revised patellar component. In most aseptic RTKAs, a well-fixed patellar component can be retained. If revision is required, a standard polyethylene component is sufficient in most septic and aseptic revisions. Rerevisions related to the patellar component are infrequent.