Anti-Gravity Simulated Weight Reduction: A Pilot Study to Assess the Impact Upon Pain for Foot and Ankle Arthritis

Abstract

Category: Ankle, Ankle Arthritis, Hindfoot, Midfoot/Forefoot Introduction/Purpose: Osteoarthritis in the foot and ankle affects approximately 30,000 patients annually in the UK. Evidence has shown that excess weight exacerbates foot pain, with significant increases in joint forces. However, despite the current UK trend for Clinical Commissioning Groups to ration surgery for obese patients, studies have not yet determined the effect of weight loss in obese patients with foot and ankle arthritis. Methods: Following ethical approval, a prospective study of 19 obese patients (mean BMI 39.2, range 31.2 – 50.3) with foot and ankle arthritis was undertaken with funding from BOFAS. Under physiotherapist supervision, patients walked for one minute on an anti-gravity treadmill, which allowed simulated weight reduction. Following baseline assessment, reduced BMI was simulated, starting at 20, rising in increments of 5, until each patient’s usual BMI was reached. Pain was assessed using a Visual Analogue Scale (VAS). Repeated measures ANOVA was used to assess for significant changes in pain, comparing baseline with each simulated BMI category (significance set at p<0.05). Results: Simulated weight loss to BMI 25 caused a significant reduction in pain (p<0.05, power 0.91). Mean VAS pain scores improved by 46% (22.8 points, p=0.002) and 32% (15.9 points, p=0.04) for BMI categories 20 and 25 respectively, compared with baseline. Pain scores were not significantly different comparing between BMI categories of 25 and 20. Conclusion: Simulated weight loss to normal BMI significantly decreased pain in obese patients with foot and ankle arthritis. The use of the anti-gravity treadmill to demonstrate the feeling of normal BMI has also provided motivation to several patients to lose weight. The current study could be used to power future studies to investigate the effects of weight loss in foot and ankle patients.