The aim of this study is to investigate the biomechanical and histological changes in the muscles after tendon injury that have been little studied previously.

Triceps insertion was tenotomized on the left hidlimbs of 60 rabbits. Mechanical extension testing with Instron (rate: 10 mm/min) was performed 1, 2, 4, 8, 12 and 16 weeks after tenotomy in vivo. A load deformation curve was obtained, and this was analyzed in terms of strength and deformation at the elastic limit and at the point of maximal load. Histologic changes were observed after H < E staining and Matson s trichrome staining to measure the percentage area of collagen fibers.

Between weeks 1 and 4, the excursion range fell gradually, and after that period, this value showed little changes. After its initial period of disequilibrium, the muscle regained its elastic nature within its newly formed excursion range. The average amount of collagen fibers increased gradually after tenotomy until 8th week.

unless tendon ruptures are repaired early, the accompanying muscle would be irreversibly damaged, both bimechanically and histologically.