Body mass index and knee arthroplasty.

OBJECTIVE

this study aims to evaluate the relationship between body mass index (BMI), age at which knee joint arthroplasty is performed and complications. The hypothesis is that the higher the BMI, the greater likelihood that the patient will require surgery at an earlier age.Methods: this is a cohort study with all patients who underwent a primary knee arthroplasty, between August 2013 and February 2019, in a tertiary level university hospital. Association between BMI, age and complications were analyzed. Quality of life of patients was also evaluated with the Oxford Knee Score (OKS).

RESULTS

565 primary total knee replacements (TKR) were performed. A cut-off point was found in BMI of 30; 348 patients had a BMI ≤30 and 173 patients had a BMI >30. When comparing the two groups, a statistically significant difference (p = 0.0186) was found in the age at which the TKR was performed. There was a significant improvement for both groups in functional score (Oxford knee score). Additionally, intra and post-operative complications showed no statistically significant difference.

CONCLUSION

patients with BMI greater than 30 required primary knee arthroplasty at a younger age (average: 3.5 years), compared to patients with a lower BMI. Obesity does not appear to confer and independent risk for surgery in the short and mid-term. Knee arthroplasty improves significantly quality of life in the short and mid-term, regardless of their BMI, as measured with the OKS.