The anterior cruciate ligament (ACL) is one of the major ligaments in the knee. It criss-crosses with the posterior cruciate ligament to help hold the two bones of the knee together.
If the ACL is torn or damaged it becomes deficient or weak. One of its important functions is to keep the lower leg bone (tibia) from sliding too far forward as the knee bends. An ACL-deficient knee doesn’t hold the tibia in place during movement as it should.
The ACL also keeps the knee from rotating or twisting the wrong way. A recent study at the University of Nebraska showed that ACL-deficient knees tend to rotate inward during walking. A normal knee rotates outward or externally.
An ACL-deficient knee can be returned to near normal status. This can be done with surgery to repair the damage. If the ligament has a minor tear, a rehab program may be able to restore the function of the knee without surgery.
Without repair, the ligament remains weak and at risk for reinjury. ACL-deficiency leads to other damage to the joint. There can be tears in the meniscus or injury to the bone. Osteoarthritis of the knee is common in patients with unrepaired (deficient) ACL ligaments.