The influence of the implant size on the outcome of unconstrained total knee arthroplasty.

INTRODUCTION: The influence of implant size on the results in unconstrained total knee arthroplasty has never been investigated before. PATIENTS AND METHODS: 133 patients with unconstrained total knee arthroplasty were examined (HSS Score, Knee Society Score) with consideration of the different sizes of femoral and tibial components and the thicknesses of the tibial inlays. The medium follow up was 41.2 months (8 months to 74 months). RESULTS: Although the different component sizes gained different results, the differences were not significant. The combination of two component sizes did not lead to a significant change of the results. The results of the Knee Society Score seemed to become worse with thinner polyethylene tibial inlays although these differences were not significant. CONCLUSIONS: In conclusion, implant size had no significant influence on the outcome of total knee arthroplasty. The combination of two implant sizes showed no disadvantage.