ACL MOI is a combo of knee ______, femoral _____, and tibial ____________.

ACL MOI is a combo of knee ______, femoral _____, and tibial ____________.

• A. extension, IR, ER
• B. extension, ER, IR
• C. flexion, ER, IR
• D. flexion, IR, ER

Answer: (A)

The main idea is that ACL injuries often occur from a twisting load applied when the knee is near full extension. When the knee is nearly extended, the ACL is already taut, so any additional load can more easily cause it to fail. If the femur rotates internally while the tibia rotates externally, the knee experiences a twisting or torsional stress across the ACL. This combination—knee near extension with internal rotation of the femur and external rotation of the tibia—places a twisting load on the ligament, increasing anterior shear and rotational strain and making rupture more likely. This pattern is common in noncontact injuries during cutting or landing, where a valgus moment accompanies the rotations.

The main idea is that ACL injuries often occur from a twisting load applied when the knee is near full extension. When the knee is nearly extended, the ACL is already taut, so any additional load can more easily cause it to fail. If the femur rotates internally while the tibia rotates externally, the knee experiences a twisting or torsional stress across the ACL. This combination—knee near extension with internal rotation of the femur and external rotation of the tibia—places a twisting load on the ligament, increasing anterior shear and rotational strain and making rupture more likely. This pattern is common in noncontact injuries during cutting or landing, where a valgus moment accompanies the rotations.