Press fit condylar cobalt chrome sigma total knee arthroplasty: no difference to original design at five year point

Background: Total knee arthroplasty (TKA) is an established procedure for relieving pain and improving function. The Press Fit Condylar Cobalt Chrome Sigma (PFCSCC) Total Knee System was introduced by Depuy, Johnson & Johnson in 2006, as an update of their existing PFC Sigma design intended to reduce backside wear.

Methods: To identify any significant early failures following the introduction of this knee system, we prospectively identified all patients undergoing TKA with the PFCSCC over a one-year period. Clinical and demographic patient data, American Knee Society scores, Oxford Knee scores, SF-12 scores and radiographic data were recorded pre-operatively and at three and five years post-operatively.

Results: 233 patients underwent 249 primary TKA's with the PFCSCC. Seventeen patients (19 TKAs) died before the last review and 29 patients (30 knees) were lost to follow up. The mean age was 66.6 (range 34-80) with 47.6% male. Mean five year follow-up was 1836. days (range 1530-2307). Five knees (2.2%) were revised for infection with three revised for pain. The 5-year survival rate was 96.6% and 98.6% for aseptic failure. American Knee Society Score (AKSS) was 32.6 (0-86.6) preoperatively and 80.7 (29-95) 5 years post-operatively P. <. 0.001. OKS was 20.9 (7-38) preoperatively and 36.4 (10-48) at 5 years P. <. 0.001.

Conclusion: We report the first five year outcome of this design change, which demonstrates a good early survivorship when compared to the previous PFC Sigma design.