The emerging science of mechanobiology is helping Duke rheumatologists assess the causes of muscular dysfunction as part of an initiative to enable more targeted interventions for patients with rheumatoid arthritis (RA).

Focusing on the effects of mechanical stimuli on muscle tissue, rheumatologists are measuring resting skeletal muscle stiffness associated with RA. Some patients with RA have muscle alterations indicative of abnormal muscle remodeling or regeneration following injury. Measurement of resting, or passive, muscle stiffness may be a novel biomarker in the assessment and monitoring of RA skeletal muscle pathology and exercise intolerance.

Brian Andonian, MD, a second year rheumatology fellow, and Kim M. Huffman, MD, PhD, a Duke researcher and rheumatologist, are collaborating with the Duke Department of Biomedical Engineering on the application of mechanobiological principles to the study of RA-related muscle abnormalities. The project is part of the Medicine and Engineering at Duke (MEDx) partnership between the School of Medicine and the Pratt School of Engineering.

"Arthritis is a disease of the bones and joints and is clearly both muscular and mechanical in nature,” Andonian says. “We think mechanobiology probably plays a big role in abnormal movement associated with arthritic disease.”

The application of mechanobiology to rheumatic disease is somewhat novel, Andonian and Huffman acknowledge, but they say the measurement of muscle stiffness may lead to significant innovations. Increased stiffness in aged muscle, in particular, may indicate a disruption in the ways cells regenerate after injury or exercise, Huffman says. Skeletal muscular stiffness may reflect muscle with more scarring as a result of impaired cellular regeneration. In this way, measures of muscle stiffness may allow identification of people most in need of muscle-improving interventions.

“Our goal is to determine the most effective ways to use currently existing interventions to improve the quality of life of our patients,” Huffman says. “While physical movement is usually recommended, pharmacologic options may be required when exercise is difficult for patients with an extreme stiffness phenotype.”