The morphology of the tibial footprint of the anterior cruciate ligament changes with ageing from oval/elliptical to C-shaped.

Purpose: To further the current understanding of the modifications of the morphology of the ACL tibial footprint in healthy knees during the ageing process. The hypothesis is that there are differences in the morphology of the ACL tibial footprint between the cadavers of the young and elderly due to a degenerative physiological process that occurs over time.

Methods: The tibial footprint of the ACL was dissected in 64 knee specimens of known gender and age. They were divided into four groups by age and gender, setting 50 years of age as the cut-off point. Three observers analyzed the tibial footprint dissections and the shape was described and classified.

Results: The knees from the cadavers of males older than 50 years of age presented a "C" morphology in 85% of the cases. In the group of males aged less than 50 years, an oval/elliptical morphology was found in 85.7% of the cases. In the group of women over 50 years-old, the "C" morphology was observed in 82.3% of the cases. In women under the age of 50, the oval/elliptical morphology was found in 84.6% of the cases. A significant difference was observed between the prevalence rates of the morphologies of the younger and older groups (p < 0.001 for both genders). However, no differences were observed between males and females of the same age group (n.s.).

Conclusions: The morphology of the tibial footprint of the ACL presents significant variations with ageing. It can go from an oval/elliptical shape to a "C" shaped morphology. The results of this work make for an advance in the individualization of ACL reconstruction based on the age and the specific morphology of the tibial footprint.