Effects of sonication on articular cartilage in experimental osteoarthritis

To investigate the histological effect of therapeutic ultrasound on arthritic cartilage of rats with various severities of induced osteoarthritis.Twenty-seven rats with 3 different stages (Grade I, II, III) of papain induced knee arthritis received 7 min pulse sonication treatment, 3 times/week for 4 weeks. Another 27 rats with the same severity of induced arthritis were studied as controls. The severity of arthritis and related histopathological changes of articular cartilage were evaluated by bone scan and histological findings with hematoxylin and eosin stain."Severity indexes" based on bone scan decreased after sonication treatment in each study group. Histopathological findings indicated marked cartilage repair in the early stage of induced arthritis (Grade I). However, progressive cartilage damage present in untreated Grade II, III induced arthritis was significantly reduced after sonication.Therapeutic ultrasound enhances cartilage repair in the early stage, and has the effect of arresting further deteriorative damage in the later stage of induced arthritis.