Search

Abstract Background Obesity is a risk factor for knee arthritis. Total knee arthroplasty is the definitive surgical treatment of this disease. Therefore, a high percentage of subjects treated are overweight. Since 2000 in the Emilia-Romagna Region the Register of Orthopedic Prosthetic Implantology, RIPO, has recorded data of all the primary and revision operations performed on the knee; height and weight of patients at the time of surgery have also been recorded. Methods To understand how overweight and obesity affect the outcome of knee arthroplasty, a population of subjects treated with cemented total knee arthroplasty between 2000 and 2005 was studied. 9735 knee prostheses were implanted in 8892 patients; 18.9% of the patients were normal weight, 48.2% were overweight (25 < Body Mass Index 40). Mean and range of follow-up were respectively 3.1 and 1.5–6 yrs. Implant failure was defined as the exchange of at least one component for whatever reason. Results In normal weight patients there were 36 failures out of 1840 implants (1.96%), in overweight patients there were 87 out of 4692 (1.85%), in obese 59 out of 3031 (1.94%), and in morbidly obese there were 4 out of 172 (2.3%). The mean time to failure for each class was 1.57, 1.48, 1.60, 1.77 yrs. Cox regression analyses showed that the risk of implant failure was not influenced by BMI, absolute body weight, or sex. Conversely, an increased failure risk was observed in mobile meniscus prostheses in comparison with those with a fixed meniscus (Rate Ratio 1.88); an increased failure risk was also related to age (Rate Ratio 1.05 per year). These results were also confirmed when considering septic loosening as the end-point. There were no differences in the rate of perioperative complications and death in the 4 classes of BMI. Conclusion In conclusion, cemented knee prostheses, implanted in patients with arthritis do not have significantly different rates of survival or perioperative complications in obese subjects compared with normal weight subjects, at least up to 5 years after surgery. The conclusion also applies to subjects affected by morbid obesity, altough this findings should be regarded with caution due to the small sample examined.

Abstract Background Total hip arthroplasty is a successful surgery, that fails at a rate of approximately 10% at ten years from surgery. Causes for failure are mainly aseptic loosening of one or both components partially due to wear of articular surfaces and partially to design. The present analysis aimed to identify risk factors and quantify their effects on aseptic failure. Methods Multivariate survival analysis was applied to 4,750 primary total hip arthroplasties performed between 1995 and 2000. Results The survival of the prosthesis is affected by gender, age, pathology, type of the prosthesis and skill of the. The worst conditions are male patients, younger than 40 years, affected by sequelae of congenital diseases, operated by a who performed less than 400 total hip artroplasty in the period. Furthermore, cemented cups and stems (less expensive) have a higher risk of failure compared with uncemented ones (more expensive). Conclusion The only variable that affects survival and that can be modified by is the type of prosthesis: a lower cost is associated to a higher risk. Results concerning the risk associated with cemented components are partially in disagreement with studies performed in countries where cemented prostheses are used more often than uncemented ones.