Force Distribution in Femoral Attachment of Anterior Cruciate Ligament During Drawer Test - A Planar Model Analysis

Injuries of anterior cruciate ligament of the knee are common, particularly in young athletes. A procedure to restore the joint function involves ligament reconstruction. A significant percentage of the patients report unsatisfactory outcome and inability to return to previous levels of activity. Further complications of the joint and repeated surgeries are also reported. Clinical and experimental studies suggest that a better understanding of the ligament and knowledge of its reconstruction requirements are needed for improved outcome. The present study used a planar mathematical model of the knee with intact ligaments and anatomical articular surfaces to analyze contributions of different fiber bundles in the ligament with distinct areas of attachment on the femoral bone in search of appropriate positions of femoral tunnel during ligament reconstruction. Knee motion during 0-120^o flexion and an anterior drawer test at different joint positions were simulated. The model analysis showed that the ACL fibers attached anteriorly on the femoral bone contributed significantly throughout the knee motion and resisted anterior loads on the tibia at all flexion positions, while the fibers attached posteriorly on the femoral bone contributed during 0 - 45^o and above 90° flexion. The results agreed with experimental observations and have clinical relevance.