The influence of obesity on patient reported outcomes following total knee replacement

Abstract

This study retrospectively analysed the effects of obesity as described by Body Mass Index (BMI) on patient reported outcomes following total knee replacement. Participants (105 females and 66 males) who had undergone surgery under the care of a single surgeon were included in the review and were grouped according to their pre operative BMI into non obese (BMI<30 kg/m²), (n= 73) obese (BMI ≥30 kg/m²) (n=98). Oxford knee score (OKS) and Short Form 12 scores (SF12) were taken pre operatively and 6 and 12 months after surgery to analyse differences between groups in the absolute scores as well as changes from pre to post surgery. Pre operatively, the obese group had a significantly poorer OKS compared to non obese (44.7 vs. 41.2, p=0.003). There were no statistically significant group effect on follow-up or change scores of the OKS and SF12. Correlations coefficients between BMI and follow-up and change scores were low (r<0.201). There were no significant differences in the number of complications and revisions (local wound infection, 6.7% non obese, 11% obese, post operative systemic complication 8% non obese 12% obese, revision 4 % non-obese, 3% obese). In conclusion, our findings indicate similar degrees of benefits from the surgery irrespective of patient BMI.