Purpose: The purpose of this study was to examine the effect of deep flexion on the long-term durability of a high-flex ceramic implant in total knee arthroplasty.
Methods: Five hundred and five consecutive knees replaced with a Bi-Surface knee system (Kyocera Medical, Osaka, Japan) were divided into two groups according to the range of flexion by 135° postoperatively. Comparison of implant durability was made between the high- and low-flexion groups after a minimum ten year follow-up.
Results: With revision for any surgery as the end point, the survival rates at ten years were 95.5% and 96.2% in the high- and low-flexion group, respectively (p = 0.63). With revision for mechanical failure as the end point, survival rates were 98.7% and 98.5%, respectively (p = 0.94).
Conclusion: Implant survival rate was similar for both groups. Deep flexion seemed not to affect long-term durability.