Post-operative Rehabilitation Following Total Knee Arthroplasty Should Include Weight Management

Abstract

The majority of persons with end-stage knee osteoarthritis (OA) are overweight and report that knee pain is a major barrier to physical activity and exercise. Total knee arthroplasty (TKA) improves functional mobility and reduces pain; however, the long-term effects of this surgical intervention on body mass index (BMI) have not been evaluated. A reduction in BMI may slow the progression of OA in the uninvolved limb and lower the chance of cardiopulmonary sequellae. PURPOSE: To determine if a reduction in body mass index was present following unilateral TKA compared to an age-matched healthy control group who did not have surgery. METHODS: One hundred and six adults with unilateral, end-stage knee osteoarthritis and 31 persons without knee pain participated in the prospective longitudinal study. Subjects with OA underwent primary unilateral TKA and received post-operative outpatient physical therapy. Height, weight, quadriceps strength and functional ability were measured at baseline and at a two year follow-up. RESULTS: There was a significant interaction effect between body mass over time and subject group (p=0.017). BMI significantly increased over two years for the surgical group (p<0.001), but not for the control group (p=0.842). Sixty-six percent of the persons in the surgical group gained weight over the two years with an average weight gain of 6.4 kg, or 14 pounds, 2 years after their initial physical therapy visit. Persons in the surgical group that gained weight also demonstrated a significant reduction in strength on the non-operated limb between 1 and 2 years after surgery (p=0.002), whereas persons that did not gain weight did not demonstrate a reduction in quadriceps strength (p=0.244). Educational level, marital status, income level and activity level prior to surgery were not related to post-surgical weight gain. CONCLUSION: The majority of subjects gain weight after surgery and this cannot be attributed to the effects of aging. Weight gain after TKA should be treated as an independent concern and management of orthopedic impairments will not result in weight loss. Post-operative care should include access to nutrition or weight management professionals in addition to medical and physical therapy services. Supported by NIH R01HD041055 and P20RR01645