Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis

Arthritis Rheum. 2005 Jul;52(7):2026-32. doi: 10.1002/art.21139.


Objective: To determine the relationship between change in body mass and knee-joint moments and forces during walking in overweight and obese older adults with knee osteoarthritis (OA) following an 18-month clinical trial of diet and exercise.

Methods: Data were obtained from 142 sedentary, overweight, and obese older adults with self-reported disability and radiographic evidence of knee OA who underwent 3-dimensional gait analysis. Gait kinetic outcome variables included peak knee-joint forces and peak internal knee-joint moments. Mixed regression models were created to predict followup kinetic values, using followup body mass as the primary explanatory variable. Baseline body mass was used as a covariate, and thus followup body mass was a surrogate measure for change in body mass (i.e., weight loss).

Results: There was a significant direct association between followup body mass and peak followup values of compressive force (P = 0.001), resultant force (P = 0.002), abduction moment (P = 0.03), and medial rotation moment (P = 0.02). A weight reduction of 9.8 N (1 kg) was associated with reductions of 40.6 N and 38.7 N in compressive and resultant forces, respectively. Thus, each weight-loss unit was associated with an approximately 4-unit reduction in knee-joint forces. In addition, a reduction in body weight of 9.8 N (1 kg) was associated with a 1.4% reduction (0.496 Nm) in knee abduction moment.

Conclusion: Our results indicate that each pound of weight lost will result in a 4-fold reduction in the load exerted on the knee per step during daily activities. Accumulated over thousands of steps per day, a reduction of this magnitude would appear to be clinically meaningful.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Body Weight
  • Diet Therapy*
  • Exercise Therapy*
  • Female
  • Humans
  • Knee Joint / physiopathology*
  • Male
  • Middle Aged
  • Obesity / complications
  • Obesity / physiopathology
  • Obesity / therapy*
  • Osteoarthritis, Knee / complications
  • Osteoarthritis, Knee / physiopathology
  • Osteoarthritis, Knee / therapy*
  • Single-Blind Method
  • Treatment Outcome
  • Weight Loss*
  • Weight-Bearing