Abstract
OBJECTIVE: The aim of this study was to examine the effects of high weight loss on knee joint loads during walking in participants with knee osteoarthritis (OA). DESIGN: Data were obtained from a subset of participants enrolled in the Arthritis, Diet, and Activity Promotion Trial (ADAPT). Complete baseline and 18-month follow-up data were obtained on 76 sedentary, overweight or obese older adults with radiographic knee OA. Three-dimensional gait analysis was used to calculate knee joint forces and moments. The cohort was divided into high (>5%), low (<5%), and no (0% or gain) weight loss groups. RESULTS: From baseline body weight, the high weight loss group lost an average of 10.2%, the low weight loss group lost an average of 2.7%, and the no weight loss group gained 1.5%. Adjusted 18-month outcome data revealed lower maximum knee compressive forces with greater weight loss (P=0.05). The difference in compressive forces between the high weight loss and no weight loss groups was due primarily to lower hamstring forces (P=0.04). Quadriceps forces were similar between the groups at 18-month follow-up. There was no difference between the groups in 18-month joint space width or Kellgren-Lawrence scores. CONCLUSIONS: These results suggest that a 10% weight loss in an overweight and obese osteoarthritic population elicits positive changes in the mechanical pathway to knee OA by having lower knee joint compressive loads during walking compared to low and no weight loss groups. The difference in compressive forces was due, in large part, to reductions in hamstring co-contraction during the initial portion of the stance phase.