Comparative assessment of the early mechanical integrity of repaired tendon Achillis ruptures in the rabbit

The effectiveness of closed versus open management of Achilles tendon ruptures was studied in a series of 40 adult rabbits. Tensile test data of tendon repair specimens excised after 10 weeks of equinus cast immobilization revealed stiffness and strength deficits, relative to uninjured contralateral tendons, ranging from 70 to 88%. Although no statistically significant differences in these early tensile properties were noted among groups managed conservatively versus those treated openly, the closed management group healed with length increases more than three times those which resulted from suture repair. Apposition of a small, longitudinal polytetrafluorethylene (Gore & Assoc., Newark, DE) patch graft in order to stimulate fibroblastic proliferation at the repair site had no biomechanical advantage over simple Kleinert suturing. The tensile test data were found to be consistent with the histological appearance of the repair sites and with detailed rupture dynamics patterns recorded by high-speed cinematography.