Electron microscopic evaluation of two-bundle anatomically reconstructed anterior cruciate ligament graft

We investigated the difference in collagen fibrils in the two-bundle anatomically reconstructed anterior cruciate ligament (ACL) and the one-bundle reconstructed ACL. Ten patients with a two-bundle anatomically reconstructed ACL using semitendinosus tendons (Two-ST) were followed for an average of 16 months (7-27 months) and were compared with 15 patients with a one-bundle ACL (One-ST) reconstruction using hamstring tendons followed for an average of 20 months (9-39 months). Biopsy was performed during second-look arthroscopy. The diameter of the collagen fibrils, their density, and the percentage of collagen fibrils were measured using electron micrography. We also investigated biopsy specimens of normal semitendinosus and gracilis tendons from 10 patients. The diameter of the collagen fibrils from hamstring tendons in the Two-ST (45.1 +/- 7.6 nm) was significantly larger than that in the One-ST (40.1 +/- 7.8 nm) ( P < 0.05). The diameter of the collagen fibrils in the normal hamstring tendons was significantly larger than that in the reconstructed ACL with hamstring tendons of the Two-ST and One-ST groups ( P < 0.01). The results of the study revealed that the diameter of collagen fibrils in the Two-ST was significantly greater than that in the One-ST. Hence, the tensile strength of the two-bundle graft may be greater than that of the one-bundle graft.