Article
In vivo heterotopic culturing of prefabricated tendon grafts with mechanical stimulation in a sheep model
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Published: | October 23, 2017 |
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Outline
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Objectives: The goal of this study is to investigate the biomechanical and histological properties of in vivo heterotopically prefabricated quadriceps tendon grafts with mechanical stimulation. The clinical goal is to heterotopically prefabricate a bone-tendon-bone graft as a viable option for ACL reconstruction.
Methods: In a sheep model, 8 quadriceps tendon grafts were harvested and fixed into culturing chambers at their proximal and distal ends. Four tendon-chamber constructs were sutured to the quadriceps muscle proximally, with additional autologous cancellous bone graft from the iliac crest, and fixed into the superior border of the patella distally, which was regarded as the mechanical stimulation group. As the group without mechanical stimulation, 4 tendon-chamber constructs were embedded into the quadriceps muscle without suturing and were distally attached to the superior border of the patella where multiple micro-fractures have been created. All sheep were sacrificed 6 weeks postoperatively and the constructs were examined biomechanically and histologically. The healthy contralateral ACL and quadriceps tendon were harvested as the control group.
Results and Conclusion: Macroscopically, no obvious ossification could be observed at the ends of the tendon-chamber constructs 6 weeks postoperatively. Histologically, the tendon tissue from the mechanically stimulated constructs revealed higher counts of cells and capillaries. However, there was less regular cell distribution and collagen fibers orientation compared to the control group. In addition, osteoclasts and osteogenesis were observed in the prefabricated constructs both with and without mechanical stimulation. Biomechanically, there were no significant differences in stiffness, elongation and ultimate failure load between the groups.
In vivo heterotopic culturing of prefabricated tendon grafts may have the potential to stimulate osteoclasts and induce osteogenesis. However, the reported surgical technique and time frame did not to macroscopically generate a bone-tendon-bone graft. Future studies with longer follow-up and modifications of surgical technique are desirable.