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.

Cite this article: Bone Joint J 2013;95-B:177–80.

We report the ten-year survival of a cemented total knee replacement (TKR) in patients aged < 55 years at the time of surgery, and compare the functional outcome with that of patients aged > 55 years. The data were collected prospectively and analysed using Kaplan-Meier survival statistics, with revision for any reason, or death, as the endpoint. A total of 203 patients aged < 55 years were identified. Four had moved out of the area and were excluded, leaving a total of 221 TKRs in 199 patients for analysis (101 men and 98 women, mean age 50.6 years (28 to 55)); 171 patients had osteoarthritis and 28 had inflammatory arthritis. Four patients required revision and four died. The ten-year survival using revision as the endpoint was 98.2% (95% confidence interval 94.6 to 99.4). Based on the Oxford knee scores at five and ten years, the rate of dissatisfaction was 18% and 21%, respectively. This was no worse in the patients aged < 55 years than in patients aged > 55 years.

These results demonstrate that the cemented PFC Sigma knee has an excellent survival rate in patients aged < 55 ten years post-operatively, with clinical outcomes similar to those of an older group. We conclude that TKR should not be withheld from patients on the basis of age.

Studies describing the effect of body mass index (BMI) on the outcome of total hip replacement have been inconclusive and contradictory. We examined the effect of BMI on medium-term outcome in a cohort of 1617 patients who underwent a primary total hip replacement for osteoarthritis. These patients were followed prospectively for five years with the outcomes of dislocation, revision, duration of surgery and deep and superficial infection studied, as well as collecting Harris hip scores (HHS) and Short-Form 36 (SF-36) questionnaires pre-operatively and at review. A multivariate analysis was performed to see whether BMI is an independent predictor of poor outcome.

We found that patients with a BMI of ? 35 kg/m² have a 4.42 times higher rate of dislocation than those with a BMI < 25 kg/m². Increasing BMI is also associated with superficial infection and poorer HHS and SF-36 scores at five years. These trends remain significant even when multivariate analysis adjusts for age, gender, prosthesis, operating consultant, pre-operative HHS and SF-36, and comorbidities including diabetes mellitus, cardiac disease and osteoporosis.

Despite the increased risks, the five-year outcome scores indicate that obese patients have much to gain from total hip replacement. Thus total hip replacement should not be withheld from patients solely on the grounds of an elevated BMI. However, longer-term follow-up of this cohort is required to establish whether adverse outcomes become more evident with time.