Extracorporeal shock wave therapy promotes cartilage repair and subchondral bone remodeling in a rat model of osteochondral lesion

Background Osteochondral lesions (OCL) are a key pathological feature in osteoarthritis (OA), necessitating effective treatments that target both cartilage and subchondral bone. Extracorporeal shock wave (ESW) therapy, a non-invasive modality, shows promise but its holistic effects on the osteochondral unit require further elucidation. Objective This study aimed to investigate the therapeutic effects of ESW on cartilage repair and subchondral bone remodeling in a rat OCL model. Methods Thirty-six Sprague-Dawley rats were randomized into Control, OCL (MIA-induced), and OCL+ESW groups. The OCL+ESW group received weekly ESW treatment (1.0 bar, 800 impulses, 6 Hz). Functional recovery was assessed longitudinally via gait analysis (CatWalk). At endpoint, knee joints were analyzed using micro-computed tomography (micro-CT) and histological staining (Safranin O-Fast Green, Toluidine Blue). Results Micro-CT revealed that ESW significantly ameliorated MIA-induced subchondral bone deterioration, restoring bone mineral density (BMD), bone volume fraction (BV/TV), and trabecular number (Tb.N) towards normal levels. Gait analysis demonstrated significant functional improvement in the OCL+ESW group from week 4, with parameters like maximum contact area and intensity normalizing by week 8. Histology confirmed marked preservation of cartilage integrity, surface smoothness, and proteoglycan content in ESW-treated animals compared to the degenerative OCL group. Conclusion ESW therapy effectively mitigates cartilage degeneration and promotes subchondral bone remodeling, leading to significant functional recovery. Our findings underscore the translational potential of ESW as a non-invasive treatment strategy for osteochondral defects and early OA. The Translational Potential of this Article This preclinical study provides robust evidence supporting ESW therapy as a viable, non-invasive treatment for osteochondral lesions. By demonstrating simultaneous efficacy on both cartilage and bone—the critical components of the osteochondral unit—it bridges the gap between basic research and clinical application, paving the way for ESW to become a first-line, disease-modifying therapy for osteoarthritis, potentially reducing the need for surgical intervention.