Abstract
Purpose
The purpose of this study were to investigate whether there is an association between the preoperative body mass index in total knee replacement patients and the effect three to five years postoperative.
Method
197 patients who had undergone primary total knee replacement in the period 1.1.2005–31.12.2006 participated in a three-five years of follow-up study. Outcome measures were self-rated health (SF-36), which consists of eight strands and two component scores, physical component score and mental component scores and the Knee Society rating system (KSS) (knee score and function scores), and improvement of the two KSS scores from baseline to follow-up.
Results
With Ordinal logistic regression (adjusted for gender, age, basic disease and surgical procedure) were found statistically significant association between body mass index and nine of the fourteen outcome measures. For all outcome measures were found OR > 1. With a difference in body mass index of 1kg/m2 increases the risk of lower scores from a minimum of 2% OR 1.02 (0.97–1.07) p=0.5 (mental component score) to maximum 14% OR 1.14 (1.08–1.21) p <0.001 (KSS function score). With a difference in body mass index on 5kg/m2 increases the risk of lower scores from a minimum of 9% OR 1.09 (mental components scores) to a maximum of 96% OR 1.96 (KSS function scores). With a difference in body mass index of 10kg/m2 rises risk of worse score with minimum 19% OR 1.19 (mental component score) to a maximum of 284% OR 3.84 (KSS function score).
Conclusion
There is a clear association between body mass index and efficacy 3–5 years following primary total knee replacement. More than half of the Outcome measures were statistically significant and the outcomes that were not statistically significant are clinically interesting. High body mass index increases the risk of poor outcome after total knee Arthroplasty.
