Observation of the ultrastructure of anterior cruciate ligament graft by atomic force microscopy

This study presented the fibril ultra-structure of retrieved grafts from the reconstruction of anterior cruciate ligament (ACL) using atomic force microscopy (AFM). The tapping mode images of the AFM were taken from different areas of the longitudinally cut grafts. Regular arrangement of collagen fibrils was found in certain areas of the graft. In many areas, however, the fibrils were not well arranged in a single direction, with some smaller fibrils oriented vertically to larger parallel fibrils. The crossing and tangling of fibrils in ACL grafts was well represented in the three-dimensional AFM image. This abnormality of graft ultra-structure might indicate the possible alteration of the mechanical environment after ACL reconstruction. This study demonstrated the suitability and importance of ultrastructure observation of ACL grafts by AFM.