Impact of Obesity on the Outcomes of Aseptic Revision Total Knee Arthroplasty.

BACKGROUND

Obesity is a known risk factor for complications following primary total knee arthroplasty (TKA), yet its impact on the outcomes of aseptic revision TKA remains less defined. This study evaluates the influence of body mass index (BMI) on revision, reoperation, and infection outcomes following aseptic revision TKA.

METHODS

A retrospective cohort of 2,836 first-time aseptic revision TKAs performed at a single academic institution from 2000 to 2022 was analyzed. Patient demographics, including BMI, were collected. The mean age was 69 years, the mean BMI was 33, and 42% were men. The main causes for the initial revisions were aseptic loosening (37%), instability (29%), and wear or osteolysis (13%). Kaplan-Meier survivorship, univariate Cox regression analyses, and multivariate Cox regression analyses adjusted for age, sex, indication for revision, and Charlson Comorbidity Index were used to assess the impact of BMI on the risks of revision, reoperation, and infection. The mean follow-up was seven years (range, two to 22).

RESULTS

The 5-year survivorships free from revision for periprosthetic joint infection (PJI), reoperation for PJI, any revision, and any reoperation were 96, 96, 89, and 85%. Univariate analyses showed that a BMI > 40 correlated with a trend toward increased reoperation for PJI (hazard ratio: 1.4, P = 0.05) and a higher risk of reoperation for any reason (hazard ratio: 1.3, P = 0.04). However, these findings did not remain significant when controlling for confounding factors with multivariate analysis.

CONCLUSIONS

Although a BMI greater than 40 did impact the risk of subsequent reoperation following revision TKA on univariate analyses, these findings did not persist when accounting for confounding factors. These results suggest that the indication for revision plays a much larger role in outcomes following revision TKA for aseptic indications than BMI alone.

LEVEL OF EVIDENCE

IV (retrospective study).