The anterior cruciate ligament (ACL) is an important ligament located in the center of the knee that functions in knee stability.

The ACL’s primary function is to resist anterolateral displacement of the tibia relative to the femur.

The ACL is comprised of two bundles:

• Anteromedial bundle

• Posterolateral bundle

It is composed of 90% Type I collagen and 10% of Type III collagen.

ACL tears typically occur via two main mechanisms:

• Non-contact pivoting injury (most common)

• Direct impact injury to the lateral aspect of the knee

Injuries are frequently associated with sports (in particular: soccer, basketball, skiing, and football), but also can be from non-sports related injuries.

Common Symptoms:

• Pain

• Significant knee swelling/effusion

• A sense of distrust or “buckling” of the knee

• Inability to return to sport

Physical Exam (performed by your surgeon):

• + Lachman ligament testing

• + Anterior Drawer testing

• Other specialty testing performed to assess for other associated injuries (MCL, LCL, etc).

Imaging:

• X-rays are often performed initially to rule out fracture.

• If there is a high degree of suspicion for an ACL tear, an MRI will be ordered by your provider. The MRI will be able to show if the ACL is torn any if there are associated injuries to the meniscus or other ligaments of the knee.

ACL reconstruction is a surgical procedure in which the torn anterior cruciate ligament is “re-built” (reconstructed) using a graft either from a different area of your knee or a donor graft.

This is typically done arthroscopically.

Bone tunnels in the femur and tibia bones are drilled to accommodate the new ACL.

Each end of the new ACL graft is fixated to the bones via screw (interference) or suspensory (button) fixation.

An ACL reconstruction is intended to return the knee to an anatomic level of stability that was present before the injury.

With restoration of knee stability and kinematics, a functional ACL allows you to participate in higher levels of activity and protects the other important knee structures (cartilage, meniscus, and other tendons/ligaments).

“Full recovery” depends on goals of activity.

Typically, for a full “return to sport” in a higher level cutting or pivoting sport requires 9-12 months of recovery time. For less high demand activities, this may only be 6 months.

Usually by 3 months post op, patients are able to run on flat ground.

In the 4-6 month range, more agility and cutting-type activities are added in by your therapist.

Autograft (your own tissue):

• Bone-patellar tendon-bone (BTB)

• Quadriceps tendon

• Hamstring tendon

Allograft (donor tissue):

• BTB

• Hamstring

• Tibialis anterior

• Peroneus longus

In my practice, the most common graft choices are BTB and quadriceps tendon autograft.

Autograft has the advantage of healing better (because it’s your own tissue), but has the disadvantage of having to take tendon away from an area that wasn’t injured before.

In younger individuals, AUTOgraft (your own tissue) has a much lower re-tear rate (~4x less) and is almost always recommended.

Each graft has specific advantages and disadvantages.