Patella resurfacing in total knee arthroplasty using metal-backed rotating bearing components: a 2- to 10-year follow-up evaluation

Management of the patella in total knee arthroplasty (TKA) has become an important issue. Patella-related complications remain a major concern and have frequently been the reason for secondary intervention, whether resurfaced or not. Common modes of failures are increased polyethylene (PE) wear, PE fractures, component dissociation (loosening or PE spinout), and patella fractures. This study evaluated 235 cases of low contact stress (LCS) TKA using a metal-backed rotating PE bearing. The setting was a large joint replacement center which has performed more than 2750 cases of LCS TKA since 1988. Cases with a follow-up shorter than 2 years were not calculated for statistical analysis but were included in postoperative complications. The mean follow-up was 4.2 years (range 2–10 years). Of the 105 cases 94.7% scored excellent or good results on a modified 100-point Hospital for Special Surgery score. Patellofemoral tracking was analyzed on axial radiographs in all cases and revealed perfect tracking in 96%. Revision surgery related to patella complications was required in 7 of 235 cases (3%), including two of PE bearing spinout and one each of infection, patella necrosis, PE breakage, patella maltracking, and traumatic patella component loosening. Four patella complications (1.7%) were related to patellofemoral maltracking, excluding the infected, traumatic, and patella necrosis cases. These results are similar to or better than those reported in the literature and complications appear to occur more frequently in cases with nonideal patellofemoral maltracking.