High Incidence of Tibial Component Loosening After Total Knee Arthroplasty Using Ceramic Titanium-Nitride-Coated Mobile Bearing Prosthesis in Moderate to Severe Varus Deformity: A Matched-Pair Study Between Ceramic-Coated Mobile Bearing and Fixed Bearing Prostheses

Background: We compared the incidence of aseptic component loosening and subsequent revision, and the survival rate between ceramic titanium-nitride-coated mobile bearing (MB) and fixed bearing total knee arthroplasties (TKAs) performed in patients with moderate to severe varus deformities. Methods: In total, 200 TKAs using advanced coated system posterior stabilized prostheses in varus deformity of mechanical axis >8° between 2012 and 2016 were retrospectively reviewed. One hundred MB (ceramic-m group) and 100 fixed bearing (ceramic-f group) prostheses were included. The matches were made according to preoperative demographics, range of motion, and severity of deformity. The mean follow-up period was not different (ceramic-m vs ceramic-f = 4.8 vs 5.1 years; P =.104). The incidence of revision TKA due to aseptic component loosening and the survival rate (failure: revision due to aseptic loosening) was investigated. Results: The incidence of revision TKA due to aseptic component loosening was 7 (7%) in the ceramic-m group and 1 (1%) in the ceramic-f group (P =.032). All cases of aseptic loosening occurred at the tibial component. The overall survival rate was 91.3% in the ceramic-m group and 98.9% in the ceramic-f group (P =.025). Conclusion: Considering the higher revision incidence and lower survival rate due to tibial component loosening, caution should be taken in tibial component fixation when using advanced coated system MB prosthesis in moderate to severe varus deformity.