The Effects of Mid-term Osteoarthritis on Muscle Performance and Subchondral Bone Microstructure

Abstract

Osteoarthritis (OA) is a degenerative joint disorder affecting approximately 595 million people worldwide, characterized by progressive cartilage degeneration and subchondral bone sclerosis, leading to disability and impaired quality of life, while sarcopenia and atrophy remain only minimally described in animal models. This study examined changes in muscle mass, muscle performance, and subchondral bone microstructure in a surgically induced mouse model of OA and compared unoperated and sham-operated knees as controls. In wild-type C57BL/6 mice, OA was induced by destabilization of the medial meniscus (DMM), and eight weeks after surgery, muscle performance, muscle mass, cross-sectional area, and subchondral bone microstructure were assessed using in vivo functional tests, muscle measurements, and high-resolution (5 µm) micro-CT. Except for a slight reduction in tibialis anterior weight after DMM, neither sham nor DMM surgery significantly altered muscle mass, cross-sectional area, or in vivo muscle performance. Micro-CT analysis showed trabecular bone loss in sham-operated knees compared with unoperated controls, whereas DMM-operated knees exhibited subchondral bone sclerosis characterized by increased bone volume, thickness, and connectivity; multivariate analyses demonstrated significant differences in bone parameters but not in muscle mass or performance. These findings emphasize the importance of proper study design, as minor surgical interventions can influence weight bearing and subchondral bone microstructure, while modest muscle wasting in mid-term OA occurred without corresponding in vivo functional impairment.