Obesity and size of the implant influence the early outcome after total knee arthroplasty

Obesity has long been adVocated as a risk factor for patients undergoing a Total Knee Arthroplasty (TKA), While the influence on outcomes of size of the prosthesis implanted has been eValuated in only feW studies. The purpose of this study Was to eValuate if, among the ample population of obese patients, the subgroup of patients With small sized implant is affected by particularly poor outcomes during the postoperatiVe recoVery. METHODS The outcome of 384 consecutiVe TKA Were eValuated preoperatiVely and at 6 Weeks, 6 months, 1 year and 2 years folloW-up, measuring the Knee Society Score and the Womac Osteoarthritis IndeX. The outcomes Were correlated to the body mass indeX of the patients, and to the size of the prosthesis implanted. RESULTS At linear multiple regression analysis (Stata softWare, 8.2 Version), all outcome parameters shoWed a slight correlation to BMI (loWer BMI – better outcome) but the differences Were not significant. Smaller size implants obtained Worse outcomes at 6 Weeks and 6 months folloWup, then at 2 years the difference Was not significant anymore. SeVere obese patients (BMI>35) treated With small size implants (tibial plateau surface <2500 mm2) reported significantly Worse outcome compared to the general population, according to all parameters considered. CONCLUSIONS According to our data, the population of patients affected by obesity and treated With a small size prosthesis obtain Worse early postoperatiVe results compared to the general population, in terms of functional recoVery and personal satisfaction. This population is therefore particularly at risk of early postoperatiVe unsatisfactory recoVery and rehabilitation program can be difficult: patients and surgeons should be Warned on the eXpected initial postoperatiVe difficulties