Calf muscle atrophy and Achilles tendon healing following experimental tendon division and surgery in rats - Comparison of postoperative immobilization of the muscle-tendon complex in relaxed and tensioned positions

We used a rat model to study the effects of immobilization of the calf musc le-tendon complex after an experimental Achilles tendon repair. Immobilizat ions of the complex in either a relaxed or tensioned position were compared by histochemical and morphometric analyses at the site of the tendon injur y as well as in the gastrocnemius and soleus muscle bellies. The type of im mobilization did not affect the healing of the tendon injury because no rer uptures occurred in either of the treatment groups and the average tendon e nd-to-end distance did not differ between the groups. However, immobilizati on in a relaxed position led to a significantly more extensive fiber atroph y in the calf muscles. In clinical practice, these results suggest that reh abilitation after Achilles tendon surgery can be early and gradually tensio n- and load-increasing without a significant increase in the risk of rerupt ure of the tendon.