Outcome of metal-backed cementless patellar components - The effect of implant design

Failure of metal-backed cementless patellar components frequently has been observed clinically. To determine the effect of component design on clinica l outcome, the authors reviewed the results of total knee arthroplasty with metal-backed patellar components of two different designs. The results of 168 total knee arthroplasties (Miller-Galante) with dome-shaped metal-backe d patellar components and 93 total knee arthroplasties Miller-Galante II wi th modified dome-shaped metal-backed patellar components were reviewed. Kap lan-Meier survivorship was determined for both groups. Revision for patella r wear or failure was done or recommended in 36 Miller-Galante total knee a rthroplasties. The cumulative survival rates at 3, 5, 7, and 9 years postop eratively were 99%, 92%, 81%, and 73%, respectively for this group. In cont rast, only three of 93 Miller-Galante II patellar components required revis ion. Catastrophic patellar component failure, typically seen with the Mille r-Galante metal-backed patellar components, was not observed with the Mille r-Galante II components. Cumulative survival of the Miller-Galante II patel la at 3, 5, 7. and 9 years postoperatively was 100%, 100%, 98.7%, and 93.2% respectively. The results of the current study show a dramatic reduction i n metal-backed component failure by design changes incorporated into the mo dified dome-shaped Miller-Galante II patellar component and highlights the importance of design on the survival of cementless metal-backed patellar co mponents.