Anterior Cruciate Ligament (ACL) Tears
ACL tears typically occur during sporting activities that require rapid change in direction and jumping. Such sports include soccer, football, and basketball. ACL tears often require surgical intervention in order to regain full function of your knee.
The bones that compose the knee (femur and tibia) are connected by important stabilizing ligaments. There are four primary ligaments in your knee: the medial collateral ligament (MCL), lateral collateral ligament (LCL), posterior cruciate ligament (PCL), and ACL. The collateral ligaments control sideways movement. The cruciate ligaments control the forward and backward movement of the knee. The anterior cruciate ligament runs at an angle in the middle of the knee. This ligament prevents the tibia from sliding out in front of the femur, and provides rotational stability to the knee (Figures 1 and 2). Approximately 50% of all injuries to the anterior cruciate ligament occur with damage to other structures in the knee, such as the articular cartilage, meniscus, LCL, MCL, and PCL.
Causes for ACL tears
ACL tears can occur during the following situations: rapid change in direction, sudden stoppage of direction, landing incorrectly from a jump or less commonly from a direct collision (Figure 3). Some studies have suggested that female athletes are at increased risk of ACL tears. Factors which may play a role in this increased incidence include physical conditioning, muscular strength, neuromuscular control, pelvic and leg alignment, and the effects of estrogen on ligament characteristics.
Symptoms and Examination
Injury to the ACL may result in an audible "pop" followed by pain, swelling, and instability. Other symptoms may include loss of range of motion, joint line tenderness, and discomfort while walking. If you are concerned about the possibility of this injury, your physician can perform specific examination tests to confirm the injury. X-rays are often obtained to rule out associated fractures. Though not absolutely necessary, an MRI may be performed to evaluate the integrity of the ACL and other knee structures (i.e. meniscus, collateral ligament, cartilage).
There are nonsurgical and surgical treatments for ACL tears. Individuals with a low level of activity may not require surgery. Bracing is one option for those who do not undergo surgery. After the pain and swelling subsides, physical therapy is helpful to regain lost motion and to strengthen the muscles to support the knee.
The ACL must be reconstructed to restore knee stability, since the ligament does not have the capacity to heal. The ligament is reconstructed with a soft tissue graft which can be obtained from the person or from a cadaver (allograft). Some of the more common graft options include the patellar tendon, hamstring tendon, and quadriceps tendon. There are advantages and disadvantages to all graft sources. Your orthopedic surgeon will assist you in determining which option is best for you. Because the healing process takes time, it may be six months or more before an athlete can return to sports after surgery. ACL reconstruction is usually performed on a delayed basis to allow the acute inflammatory process to calm down. ACL reconstruction that is performed too early increases the risk of scar formation in the joint resulting in loss of knee motion.
ACL reconstruction is performed in a minimally invasive manner using specialized tools which results in less postoperative pain and shorter recovery time. Techniques have continued to evolve resulting in improved stability and outcomes for athletes and non-athletes alike. Currently there are a handful of surgeons in the U.S. who perform "double bundle" ACL reconstructions which involves anatomically reconstructing the ACL to improve stability of the knee in high demand individuals. One of our surgeons, Dr. Fady Bahri has pioneered the "all inside double bundle" technique which results in anatomic ACL reconstruction with minimal disruption of surrounding soft tissues and bones of the knee.