ACL Volume Measurement Using a Multi-truncated Pyramid Shape Simulation.

Purpose: The purpose of this study was to measure anterior cruciate ligament (ACL) volume in a newly reported multi-truncated pyramid shape simulation using axial magnetic resonance imaging (MRI) for the detailed knowledge of the ACL anatomy.

Methods: Fifty subjects (27 female and 23 male, average age: 23 ± 7.8) visiting our clinic with knee pain and in whom MRI showed no structural injury were included in this study. Using the axial image of the MRI, four deferent levels of the cross-sectional area of the ACL were measured. ACL height was measured as the distance between the most proximal and distal slices of the MRI. ACL volume was calculated using a multi-truncated pyramid shape simulation. Femoral intercondylar notch height, area, and trans-epicondylar length (TEL) were also measured using MRI.

Results: The measured top, proximal 1/3, distal 1/3, and bottom of the ACL cross-sectional area were, 36.8 ± 10.7, 59.9 ± 15.4, 66.4 ± 20.8, and 107.3 ± 21.1mm, respectively. ACL height was 26.3 ± 3.9 mm. Using these data, the calculated ACL volume was 1755 ± 874mm. Significant correlations were observed between ACL volume and notch height, area, and TEL.

Conclusion: Similar ACL volume with previous reports was obtained in this simple and easy multi-truncated pyramid shape simulation from axial MRI evaluation. Significant correlation was observed between ACL volume and knee bony morphology. The ability of surgeons to measure ACL volume simply and effectively can be useful for the detailed ACL anatomical knowledge, and also for prediction and prevention of ACL injury.: IV, Case series.