Characterization of the Anchoring Morphology and Mineral Content of the Anterior Cruciate and Medial Collateral Ligaments of the Knee

The manner in which ligament connects to bone remains an area of interest for researchers, bioengineers, and clinicians. Stable fixation of an anterior cruciate ligament (ACL) graft has been shown to be paramount to preventing excess anterior tibial translation and to restoring the normal kinematics of the knee joint. In this study, the surface area of attachment and the mineral characteristics of the ACL and medial collateral ligament (MCL) attachment sites were characterized to determine the factors that contributed to ligament attachment strength. Findings from this study indicated that the area of attachment of the ACL's insertion was significantly greater than the ligament's origin (95.8 mm2 ± 21.5 vs. 73.2 mm2 ± 16.2, P = 0.009). Additionally, the ACL was measured to have a greater surface area of attachment when compared with the MCL (84.5 mm2 ± 18.8 vs. 58.2 mm2 ± 23.8, P = 0.005); although, the MCL was observed to have a greater region of calcified fibrocartilage (CFC) than the ACL (533.0 μm ± 116.9 vs. 195.5 μm ± 36.6, P = 0.0003). No significant correlation was observed between the ligament's area of attachment and the thickness of the CFC region. Measurements of ash percent suggested that the boundary region, between the CFC and host bone, possessed the least mineral content for the three regions of interest. These data suggest that ligament attachment strength can be attributed to several factors, including the ligament's area of attachment, regional thickness, and mineral content of the CFC. Anat Rec,, 2011. © 2011 Wiley‐Liss, Inc.