Does Functional Gain and Pain Relief After TKR and THR Differ by Patient Obese Status?

Introduction: Obesity is an important predictor of functional status and pain after total knee (TKR) and total hip (THR) replacement. However, variations in pre-post TKR and THR changes in function and pain by obesity status remain to be examined. Material & Methods: Pre- and 6 month post surgery data were collected on 2,964 primary TKR and 2,040 primary THR patients between 5/2011 and 3/2013. Data included demographics, comorbidities, operative joint pain severity based on the Knee Injury or Hip Disability and Osteoarthritis Outcome Score (KOOS/HOOS), WOMAC pain (higher is better), physical function (SF-36 PCS, higher is better), mental health (SF-36 MCS), and musculoskeletal burden of illness. Pre-post changes in PCS and pain were analyzed using descriptive statistics. Results: TKR patients were average 67 years, 61% women, 93% whites, 13% under or normal weight, 33% overweight, 29% obese, 15% severely obese, 9% morbidly obese. Greater level of obesity was associated with lower PCS at baseline and 6 month, lower pain scores at baseline but larger improvement post-op. Pre to-6 month PCS did not differ by obesity status. At 6 months morbidly obese patients had slightly lower/worse pain score. THR patients were average 65 years, 62% women, 95% whites, 27% under/normal weight, 38% overweight, 23% obese, 9% severely obese, 4% morbidly obese. Greater level of obesity was associated with lower PCS at baseline and 6 month, poorer baseline pain score but larger improvement post-op. Mean changes in pre-to-6 month PCS did not differ by obesity status. Conclusion: At 6 months after TKR, severely obese patients (BMI\u3e35) reported improvements in both pain and function equal to or greater than patients with BMI35 had lower mean functional gain than those with BM