Weight Loss In Knee Osteoarthritis: Effects On Knee-joint Loads, Inflammation, And Disease Progression

Abstract

PURPOSE: The aim of this study was to examine the effects of high versus low weight loss on knee joint loads and pro inflammatory biomarkers in older adults with knee osteoarthritis. METHODS: Data were obtained from a cohort of participants enrolled in the Arthritis, Diet, and Activity Promotion Trial (ADAPT). A 3D inverse dynamics analysis of the lower extremity was used to calculate quadriceps, hamstring, and gastrocnemius muscle forces, and compressive and shear knee joint forces. Baseline and followup serum levels of pro inflammatory biomarkers were analyzed using standard ELISA kits. Samples were measured in duplicate and the average value used for analyses. RESULTS: The high weight loss group lost an average of 8.2% of baseline body weight, while the low weight loss group gained 0.7%. Adjusted 18 month outcome data revealed that maximum knee compressive force, maximum gastrocnemius force, and maximum hamstring force were significantly (p ≤ 0.05) lower in the high weight loss group. Quadriceps forces were similar between the groups at 18 month follow-up. Serum leptin levels were significantly (p < 0.0001) lower in the high weight loss group at follow-up. The high weight loss group had 59% lower values relative to the low weight loss group. There were no between group differences in IL-6, CRP, TNFa, or TNF-sR1. Kellgren-Lawrence scores on the most affected knee at 18 month follow-up were not statistically different between the weight loss groups (p = 0.13). The high weight loss group showed no disease progression, whereas in the low weight loss group there was a 16% progression. CONCLUSION: These results suggest that an 8% weight loss in an overweight osteoarthritic population elicits positive, yet modest, changes in both the mechanical and inflammatory pathways to knee osteoarthritis by significantly reducing knee joint compressive loads and serum leptin levels.