We report ten-year clinical and radiological follow-up data for the Sigma Press Fit Condylar total knee replacement system (Sigma PFC TKR). Between October 1998 and October 1999 a total of 235 consecutive PFC Sigma TKRs were carried out in 203 patients. Patients were seen at a specialist nurse-led clinic seven to ten days before admission and at six and 18 months, three, five and eight to ten years after surgery. Data were recorded prospectively at each clinic visit. Radiographs were obtained at the five- and eight- to ten-year follow-up appointments. Of the 203 patients, 147 (171 knees) were alive at ten years and 12 were lost to follow-up. A total of eight knees (3.4%) were revised, five for infection and three to change the polyethylene insert. The survival at ten years with an endpoint of revision for any reason was 95.9%, and with an endpoint of revision for aseptic failure was 98.7%. The mean American Knee Society Score (AKSS) was 79 (10 to 99) at eight to ten years, compared with 31 (2 to 62) pre-operatively. Of 109 knee with radiographs reviewed, 47 knees had radiolucent lines but none showed evidence of loosening.

A small proportion of patients have persistent pain after total knee replacement (TKR). The primary aim of this study was to record the prevalence of pain after TKR at specific intervals post-operatively and to ascertain the impact of neuropathic pain. The secondary aim was to establish any predictive factors that could be used to identify patients who were likely to have high levels of pain or neuropathic pain after TKR. A total of 96 patients were included in the study. Their mean age was 71 years (48 to 89); 54 (56%) were female. The mean follow-up was 46 months (39 to 51). Pre-operative demographic details were recorded including a Visual Analogue Score (VAS) for pain, the Hospital Anxiety and Depression score as well as the painDETECT score for neuropathic pain. Functional outcome was assessed using the Oxford Knee score. The mean pre-operative VAS was 5.8 (1 to 10); and it improved significantly at all time periods post-operatively (p < 0.001): (from 4.5 at day three to five (1 to 10), 3.2 at six weeks (0 to 9), 2.4 at three months (0 to 7), 2.0 at six months (0 to 9), 1.7 at nine months (0 to 9), 1.5 at one year (0 to 8) and 2.0 at mean 46 months (0 to 10)). There was a high correlation (r > 0.7; p < 0.001) between the mean VAS scores for pain and the mean painDETECT scores at three months, one year and three years post-operatively. There was no correlation between the pre-operative scores and any post-operative scores at any time point. We report the prevalence of pain and neuropathic pain at various intervals up to three years after TKR. Neuropathic pain is an underestimated problem in patients with pain after TKR. It peaks at between six weeks and three-months post-operatively. However, from these data we were unable to predict which patients are most likely to be affected.

We present the results of a prospective study on the functional outcome from total knee replacement (TKR) in young versus old patients. American Knee Society and pain scores over ten years post TKR were compared using a cohort of young patients (≤55 years) and a control group of patients ≥56, matched for ASA, body mass index and preoperative condition. A total of 24 young and 24 older knees were analysed. All scores improved significantly over time. There was no statistical differences over 10 years in pain (p = 0.436) and knee performance (0.618). Overall function was consistently higher in the younger group (p = 0.004). TKR in younger patients produces similar outcomes in terms of pain and function compared with older patients and we feel that TKR should not be withheld on account of age alone.

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 pre-operatively 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.