Good Quality of Life in Severely Obese Total Knee Replacement Patients: A Case-Control Study

The impact of obesity on total knee replacement (TKR) outcomes is unclear. Studies use different classifications of obesity and heterogeneous methods, making comparisons difficult. The aim of this study was to evaluate health-related quality of life (HRQL) preoperatively and at 12 months of follow-up in severe and morbidly obese patients with knee osteoarthritis and a control group of nonobese patients undergoing TKR. Case-control study with 12 months follow-up. HRQL was measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. Sociodemographic variables, comorbidity, body mass index (BMI), degree of intra-operative difficulty (IOD), in-patient data, and postoperative medical data were collected. The effect size (ES) was measured for the different outcome measures. Comparison of the two groups after 12 months of follow-up was made using the t test. Study group: sixty patients (88% women) with a mean age of 70.2 years (SD 6.7) and mean total WOMAC dimension score 61.4 (SD 16.7). Control group: 60 matched controls. There were 88% women, with a mean age of 71.7 years (SD 6.7), and a mean WOMAC score of 58.2 (SD 13.4). There were significant improvements in all WOMAC dimensions compared to baseline (p < 0.001) in both groups. There were no differences in WOMAC dimension scores between the two groups at 12 months. The study group had more IOD (p = 0.014) and more-severe complications in the follow up. Severe and morbidly obese and nonobese patients had similar change scores and TKR outcomes in terms of HRQL at 12 months after TKR. Obese patients had more intraoperative difficulties and more-severe postoperative complications.