Background: Ligaments and tendons are similar in composition but differ in proportion and arrangement. Tendons are used as grafts for the ACL reconstruction. The microscopic structure of these tendons has not been sufficiently studied and compared to the native ACL.
Objective: To compare the structure of the patellar tendon graft with the structure of a normal anterior cruciate ligament.
Material and methods: A null hypothesis was declared stating that the anterior cruciate ligament should be histologically, morphologically and functionally different from the patellar tendon used for ACL reconstruction. We investigated similarities and dif-ferences of the structure of ACL and patellar tendon used as a graft tissue for ACL reconstruction. In this study, samples of patellar tendon, and the ACL were harvested from 18 patients during ACL reconstruction and analysed by light and electron microscopy, immunohistochemistry and morphometry.
Results: The thickness of the collagen fibrils, collagen organization and diameter, the fibril/interstitium ratio, density of fibroblasts and blood vessels, and distribution of the collagen type I, III and V fibrils were analyzed.
Discussions: The ACL had the highest concentration of type III and V collagen fibrils as well as elastic fibers.
Conclusion: The histological and ultrastructural appearance of the ACL differs from patellar tendon used as graft for ACL reconstruction.