Tendon regeneration: an anatomical and histological study in sheep.

Utilization of the hamstring tendon in reconstruction of the anterior cruciate ligament (ACL) has become common in recent years. In MRI studies regeneration potential in harvested tendon has been observed. In the present study, 20 legs from ten sheep, which underwent 10 cm segment resection of tendon of musculus extensor digitalis lateralis (MEDL) were used. The sheep were killed 6 months after the operation and regenerated tendons were examined macroscopically and histologically. Dissection was performed in the tendon resection area and specimens were reharvested for histological examination. Regeneration of the tendon with normal anatomical topographies was found in all legs. Regeneration occurred on both sides of the resected tendon simultaneously. Regeneration was muscle-like in the proximal side but it was tendon-like in the distal side. The developed tendon was fused to the joint capsule and to the fascia at the joint line in all specimens. This study indicates that tendon has a potential for regeneration.