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Abstract
Introduction: It is theorized that those with knee osteoarthritis (OA) exhibit a specific phenotype of high fat mass and bone mineral density (BMD) that is associated with increased knee forces and disease progression. Whether this relationship is mediated by biomechanical factors has not been investigated. Therefore, the purpose of this study was to investigate the associations between leg BMD, fat mass, and lean mass on knee joint compressive forces in older adults with knee OA, and to determine whether these relationships are mediated by stride length, leg strength, and/or knee stiffness.
Methods: Baseline DXA scans, knee extensor strength, and gait data from 75 participants from the Strength Training for Arthritis Trial (START) were analyzed.
Results: Leg BMD (p= 0.006) and fat mass (p<0.001) were positively correlated with knee joint compressive forces. Stride length, average knee stiffness, and leg strength were partial mediators for the relationship between % fat and knee forces. Leg strength was also a partial mediator for the relationship between leg BMD and knee forces,
Conclusion: Elderly obese individuals with knee OA should reduce their % fat and stride length, or alter their leg strength and knee joint stiffness to lower knee joint compressive forces.