PFC Sigma Cobalt-Chrome Total Knee Replacement: Early Outcomes Demonstrate No Significant Early Failures at the Three-Year Mark

Abstract

The PFC Sigma Cobalt Chrome Sigma (PFCSCC) was introduced in 2006, and represents further development of the PFC Sigma design aiming at reducing the problem of backside wear. To ensure that there were no significant early failures following the introduction of this knee system to our hospital in 2006, 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 preoperatively and at three-year post surgery. 233 patients underwent 249 primary knee arthroplasties with the PFCSCC. Seven patients (eight TKAs) died before the last review and eight cases were lost to follow up. Mean age was 66.7 (range 34 - 80) with 47.6% male. Mean follow-up days were 1109 (range 741 to 1591). 5 (2.2%) were revised for infection with 1 revised for pain. The 3-year survival rate was 97.6% and 99.6% for aseptic failure. AKS 46.2 (0 - 95) was preoperatively 88.3 (17 - 100) with 3 years P 0.001. OKS 39.0 (22 - 53) was preoperatively 22.6 (12 - 53) with 3 years P 0.001. 17 of the 219 who had x-rays (8%) had radiolucent zones on x-ray. Our results demonstrate a good early aseptic survivorship of the PFCSCC at three years of 99.6%, combined with a good functional and objective improvement in our patients in three years.