Background: It is necessary to create bone tunnels within the native footprint during anatomic anterior cruciate ligament (ACL) reconstruction. Predicting the size of the ACL preoperatively may be useful in order to determine the diameter of the bone tunnels preoperatively or during surgery. The tibial insertion site of the ACL includes a depressed area, the ACL fovea, which is generally observed in the sagittal view on magnetic resonance imaging (MRI). The purposes of this study were to measure the anteroposterior diameter of the ACL fovea in the sagittal view on MRI and to investigate its associations with the physical characteristics of patients.
Methods: One hundred patients (100 knees; 50 males and 50 females; mean age, 33 years) were included in this study. The anteroposterior diameter of the ACL fovea was measured in the sagittal view on MRI. The relationships between the diameter of the ACL fovea and physical characteristics including height, weight, and body mass index (BMI) were analyzed.
Results: The mean diameter of the ACL fovea was 16.1 mm in male patients and 14.3 mm in female patients, which were comparable to the previously reported values. There were significant positive correlations between the diameter of the ACL fovea and height and weight, but not BMI. The number of knees in which the diameter of the ACL fovea was <13 mm was 14 (14 %), and females were more likely to have ACL fovea diameter <13 mm.
Conclusions: The study indicated that it is possible to predict the size of the ACL before surgery by measuring the diameter of the ACL fovea on MRI. Physical characteristics of patients correlated with the diameter of the ACL fovea. Especially in female patients, it is important to consider the size of the ACL preoperatively.