Crimp morphology in the ovine anterior cruciate ligament.

While the crimp morphology in ligaments and tendons has been described in detail in the literature, its relative distribution within the tissue has not been studied, especially in relation to the complex multi-bundle arrangement as is found in the anterior cruciate ligament (ACL). In this study, the crimp morphology of the ovine ACL was examined topologically and with respect to its double-bundle structure. The crimp morphologies were compared with the knee in three knee positions, namely stance, maximum extension and maximum flexion. As a control, the crimp morphology of the ACL free from its bony attachments was determined. In the control samples, the anterior-medial (AM) bundle contained a combination of coarse and fine crimp, whereas the posterior-lateral (PL) bundle manifested only a coarse crimp. Using the extent of crimp loss observed when subjecting the knee to the respective positions, and comparing with the controls, the crimp morphologies show that the AM bundle of the ACL is most active in the stance position, whereas for the maximum extension and flexion positions the PL bundle is most active. We propose that these differences in crimp morphologies have relevance to ACL design and function.