O1361 WHAT IS THE OPTIMUM FIXATION OF THE TIBIAL COMPONENT IN PATIENTS YOUNGER THAN 65 YEARS?

Abstract

Aims: To prospectively study the optimum fixation of the tibial component in patients younger than 65 years, where the mode of fixation is randomized. Methods: 35 patients (mean age 56 years, range 29 to 64) were operated with the Profix (Smith& Nephew) TKA due to gonarthrosis grade III to V. The patients were randomly allocated to fixation of the tibial component with cement (Group C) (n=6), uncemented fixation with hydroxyapatite coating (HA) without screws (Group HA−) (n=14), or uncemented fixation with HA coating and with screws (Group HA+) (n=15). Radiostereometry (RSA) was performed postop., 3, 12 and 24 months postop. Results: There were no complications or revisions during the follow-up. Up to 3 months the cemented implants migrated the least and the HA- group the most (P = 0.009 – 0.036). From 3 to 24 months however, the implants in all three groups displayed very small migration, magnitudes well below the detection limit of RSA, and there were no differences between the three groups. Conclusions: The uncemented tibial component displays relatively large migration within the first 3 months compared to the cemented implant, and uncemented fixation without screws have larger migration than when screws are used. This larger initial migration for the uncemented fixation probably is due to “setting-in” of the prostheses. However, if the uncemented HA-coated implant “survives” this early period, the results of the present study indicate a good long term prognosis, even in designs where no screws are used for additional stability.