Journal of health sciences, Hiroshima University Volume 6 Issue 1
2006-12-28 発行


Repair process of the rat Achilles tendon after tenotomy
Ando, Yuko
Usami, Seigo
Hayakawa, Minoru
To investigate the regenerating ability and healing process of the rat Achilles tendon, the tendon was cut and its repair process was observed up to 6 months without hindlimb casting. The gap between severed tendons was filled with soft connective tissue at 3 days postoperatively and bridged by fibrous connective tissue at 1 week. By light microscopy, tendons showed a small number of tenoblasts with an ovoid nucleus and rich cytoplasm among tenocytes which contained a thin nucleus and scanty cytoplasm at 3 days. Tenoblasts increased in number at 1 and 2 weeks, and decreased at 4 weeks onward. Blood vessels were located at the peripheries of the regenerating portion at 3 days, increased in number and distribution throughout the regenerating portion and tendon at 2 weeks, and decreased at 4 weeks afterwards. Fibroblasts and collagen fibers at the regenerating portion were small in number at 3 days, increased at 1 and 2 weeks, and oriented along the long axis of tendon at 2 and 4 weeks. It was difficult to discriminate between severed tendon and the regenerated portion at 4 weeks. Cartilage was observed in some specimens at 4 weeks, and bones were found in all specimens at 3 and 6 months. These findings indicate that fibroblasts derived from both tendon and surrounding connective tissues are involved in repair, and that the repair process of tendon seems most active at 2 weeks after surgery. Regenerated tendons are considered to restore principal tendon structure at 4 or, at the latest, 6 weeks. Thus, Achilles tendon has an intrinsic ability to repair within several weeks, which provides a rationale for consideration of medical treatment and planning of early rehabilitation.
Achilles tendon