Body Mass Index Classification Is Independently Associated with Health-Related Quality of Life after Primary Total Knee Arthroplasty: An Institutional Registry-Based Study.

The purpose of this study was to compare the health-related quality of life (HRQoL) before and after successful total knee arthroplasty (TKA) across World Health Organization (WHO) body mass index (BMI) classifications. Through an institutional registry, patients with end-stage knee osteoarthritis who received elective primary unilateral TKA were identified and categorized based on WHO BMI classification. Age, gender, laterality, year of surgery, and Charlson-Deyo comorbidity index were recorded. The primary outcome was the EQ-5D-3L index and visual analog scale (VAS) at 2 years postoperatively. Inferential statistics and regression analyses were performed to determine associations between BMI classification and HRQoL. EQ-5D-3L index and VAS scores were significantly different across BMI classes, with higher scores in patients with lower BMI at baseline and at 2 years. There was no difference observed for the 2-year change in EQ-VAS scores between groups, but there was a statistically greater increase in index scores for more obese patients. In the regression analyses, there were statistically significant negative effect estimates for EQ-VAS and index scores associated with increasing BMI class, particularly for class III obesity. Higher BMI classification is independently associated with lower HRQoL scores 2 years after uncomplicated primary TKA, although obese patients experienced greater benefits in EQ-5D index scores following TKA. These results detail the relationship between BMI and HRQoL following TKA and suggest that preoperative weight loss may lead to improved outcomes following TKA, but also that obesity, alone, should not be a contraindication to TKA.