Effect of extracorporeal shockwave therapy on nanostructural and property responses of the Achilles tendinitis rat model

Extracorporeal shockwave (ESW) therapy is popular in the treatment of musculoskeletal injuries, but the mechanism by which ESW therapy might have an effect on a tendon injury is unknown. Therefore, this study examined the effects of ESW therapy on the progressive changes in the nanostructure and adhesion force of collagen fibrils of a rat Achilles tendinitis model induced by collagenase, using atomic force microscopy. The nanostructural progressive changes in morphology including the fibril diameter and D-periodicity, and properties such as the fibril adhesion force in each healing phase, were investigated over a 9-week period after injecting collagenase. The injured collagen network structures with the physical ESW therapy were returned to a well-aligned normal collagen network nanostructure. These results suggest that physical ESW therapy may promote the healing response to Achilles tendinitis.