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

Abstract

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 9.8N (1 kg) was associated with reductions of 40.6N and 38.7N in compressive and resultant forces, respectively. Thus, each weight-loss unit was associated with an ϳ4-unit reduction in knee-joint forces. In addition, a reduction in body weight of 9.8N (1 kg) was associated with a 1.4% reduction (0.496 Nm) in knee abduction moment. Conclusion. Our results indicate that each poundof 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.The precise etiology of osteoarthritis (OA) is unknown; however, several risk factors have been identified, including age (1,2), female sex (3), and both occupational (4,5) and sports-related joint stress (6-9). The most important modifiable risk factor for the development and progression of OA is obesity (1,10-17). Weight loss reduces the risk of symptomatic knee OA (13), and for obese patients with knee OA, weight loss and exercise are recommended by both the American College of Rheumatology and the European League Against Rheumatism (18,19). We have shown that an average weight loss of 5% over 18 months in overweight and obese adults with knee OA results in an 18% improvement in function. When dietary changes are combined with exercise, function improves 24% and is accompanied by a significant improvement in mobility (20).Although obesity is strongly associated with knee OA, some obese but otherwise healthy adults adapt to their excessive weight and subsequently reduce kneejoint torques and possibly knee-joint forces during walking (21). In other obese adults, however, excessive biomechanical joint stress represents one possible pathway for the pathogenesis and progression of knee OA. We hypothesized a significant and direct relationship between weight loss and attenuation of knee-joint forces and moments during walking in overweight and obese older adu...

Do Laterally Wedged Insoles or Valgus Braces Unload the Medial Compartment of the Knee in Patients With Osteoarthritis?

“…Persons who are overweight with varus alignment will benefit greater owing to the interaction between alignment and body mass on dynamic knee joint loading with the association between alignment and load highest in patients with the highest mass [17,19]. One study reported that a reduction in body weight of 1 kg (10 N) was associated with a 1% reduction (0.496 Nm) in knee adduction moment [17]. In comparison with our results, in which we observed a reduction of 4% of peak knee adduction moment in the insole group, weight reduction should be highly effective.…”

Overweight and health problems of the lower extremities: osteoarthritis, pain and disability

“…In addition to these findings, it is meaningful to examine whether weight loss might prevent OA or delay its progression. Messier et al (39) indicated that each pound ( , 0?5 kg) of weight loss will result in a fourfold reduction in the load exerted on the knee per step during daily activities. Zamboni et al (38) also suggested that even small amounts of weight loss might be beneficial.…”

The impact of obesity on the musculoskeletal system

“…59 A subset of the ADAPT study cohort underwent biomechanical analysis testing over an 18-month period. 60 There was a significant relationship between weight loss and reduction in compressive knee-joint loads, with a four-pound reduction in knee-joint load per step for every 1 pound weight loss. To date, there are no longitudinal studies evaluating if weight loss slows the progression of knee OA but this effect would appear to be clinically plausible.…”