anterior cruciate ligament What is an ACL?

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1 Treatment for a once devastating knee injury has evolved. Previously, for those suffering an anterior cruciate ligament (ACL) injury, an active life was impossibility. With advances in surgical technique based upon recent discoveries of the true and accurate anatomy of the normal ACL, athletes of all ages and abilities can once again enjoy an active lifestyle. The ACL is a ligament located in the middle of the knee that connects the femur to the tibia. It is a critical ligament that stabilizes the knee during sports and physical activity. The number of ACL injuries has increased over the years, likely due to the rise in participation in sports. Not surprisingly, there has also been an increase in the number of ACL surgeries performed. ACL reconstruction surgery is one of the most common orthopedic procedures performed today. There are over 200,000 ACL tears each year in the United States. Most of these injuries occur in individuals between the ages of 15 to 25 years of age. Fortunately, during the same time, the surgical techniques for restoring the ACL have improved greatly. What is an ACL? ACL is the medical abbreviation for the anterior cruciate ligament. The ACL is one of four major ligaments of the knee and stops the lower leg (tibia) from moving forward in relation to the thigh (femur) while providing rotational stability of the knee joint. Two bundles of fiber combine to make the ACL. American Academy of Orthopaedic Surgeons. ACL Injury: Does It Require Surgery. Available at:

2 What do the two bundles of the ACL actually look like? The ACL is one ligament with two distinct bundles that combine to stabilize the knee joint. Anterior/posterior stability is secured by the AM (anteromedial) bundle, while the PL (posterolateral) bundle provides rotational stability. Causes of ACL Injuries Any athletic movement that forces the knee into hyperextension and/or rotation can tear the ACL. Photo from Br J Sports Med 2005;39: doi: /bjsm Photo from ADAM A sedentary person may also experience an ACL tear in the same manner-- without participating in a sport activity if the knee is forced into hyperextension and/or rotation.

3 Signs/symptoms of an ACL tear After an ACL injury, one will experience pain, swelling, decreased ability to flex and extend the knee, and diminished ability to contract the quadriceps. Surgery cannot be performed until the immediate symptoms are resolved often a period of several weeks. Until the surgery, the athlete will need to complete physical therapy to prepare for the surgery. Do ACL injuries heal? The ACL will not heal once torn, as it lacks the vascularization and tissue type to promote healing of the tear. Scar tissue may develop due to the tear of a ligament, but in the case of an ACL, this scar tissue may serve to limit joint range of motion. Must all ACL tears be surgically repaired? ACL tears cannot be repaired (torn ligament tissue sewn back together). ACL tears must be reconstructed (rebuilt using another tissue, usually hamstring tendon). Not all ACL injuries require reconstruction. If an ACL is not reconstructed, the individual must modify his physical activity and may require the use of a brace to perform certain activities. Additional injury may occur if one engages in activities that involve pivoting and cutting movements, even simple daily activities. This additional damage may eventually lead to debilitating osteoarthritis. Patient with an ACL deficient knee, no surgical intervention, showing arthritic change

4 How are ACL Injuries Reconstructed? The graft for the surgery may come from either your own body, which is an autograft, or from a cadaver, which is an allograft. The most common sites of the body from which autografts are harvested are the Hamstring tendon and Patellar tendon. Many surgeons prefer using the allograft, or donor, tissue. Allograft tissues are thoroughly screened by tissue banks for disease. Pictures from ACLsolutions.com with credit to Seif Medical Images Differences between single-bundle versus a double bundle ACL Reconstruction The single-bundle surgical technique uses a single graft that replaces the AM bundle and does not address the PL bundle, leaving the knee in a compromised state. A large percentage of patients complain of instability following ACL Single-Bundle surgery. Arthritis has also been found to develop in these same patients. It is also more common for Single- Bundle patients to reinjure the ACL, tearing the surgically repaired ligament.

5 The same patient with an ACL reconstructed knee from years before, also showing arthritic change Dr. Galland performs the doublebundle technique and uses two separate grafts to replicate the AM and PL bundles. Having both AM and PL bundles surgically repaired is more likely to restore the knee to its original stability. The Anatomic Double-Bundle technique decreases the likelihood of all of the problems associated with the traditional single-bundle technique, while increasing overall knee stability. This success is accomplished using the Double-Bundle technique by reproducing the original number of ligament bundles that compose the ACL, which in turn matches or exceeds the natural tensile strength. After the Double-Bundle reconstructive surgery, normal or near-normal range of motion is restored.

6 Research Bedi, et al. A Comparison of the Effect of Central Anatomical Single-Bundle Anterior CruciateLigament Reconstruction and Double-Bundle Anterior Cruciate Ligament Reconstructionon Pivot-Shift Kinematics. The American Journal of Sports Medicine. September 2010 vol. 38 no Casagranda, et al. Normal Appearance and Complications of Double-Bundle and Selective Bundle Anterior Cruciate Ligament Reconstructions Using Optimal MRI Techniques. The American Journal of Radiology. 2009; 192: Bencardino, et al. MR Imaging of Complications of Anterior Cruciate Ligament Graft Reconstruction. The Journal of Continuing Medical Education in Radiology. November 2009;29, Adachi, et al. Reconstruction of the Anterior Cruciate Ligament: Single Versus Double- Bundle Multistranded Hamstring Tendons. The Journal of Bone and Joint Surgery. 2004;86 B: Tsai, et al. All-Inside Single-Bundle and Double-Bundle Anterior Cruciate Ligament Reconstruction: A Biomechanical Study. The American Journal of Sports Medicine. February 2010 vol. 38 no Porucznik, M. A. Is double-bundle ACL repair better? American Academy of Orthopedic Surgeons. December 2010 Volume 4, Number 12