The anterior cruciate ligament, commonly known as the ACL, is one of the most commonly injured ligaments in the knee. Running diagonally through the middle of the joint, the ACL works together with three other ligaments to connect the femur (thigh bone) to the tibia (the larger of the two lower leg bones). A tearing of this ligament causes the knee to become unstable and the joint to slide forward. ACL injuries occur most often in athletes as a result of direct contact or an awkward fall. About half of all ACL injuries are also accompanied by damage to the meniscus, cartilage, bone or other ligaments in the knee.
Causes of an ACL Injury
The ACL ligament most frequently tears as a result of a sudden turn or change of direction that causes the knee to twist or hyperextend. Such an injury most often occurs in sports that involve abrupt stops and changes in direction, such as tennis, football, soccer and basketball. It may also occur as a result of an automobile or skiing accident. Many ACL ligament tears also result from commonplace accidents like falling off a ladder or missing a step on a staircase.
Risk Factors for an ACL Injury
Women are more likely to experience an ACL tear than men, even when they are engaging in the same activities. This is because women have a strength imbalance in their thighs, with the quadriceps, the muscles at the front of the thigh, being more powerful than the hamstrings, the muscles at the back.
Symptoms of an ACL Injury
Signs of an ACL injury are difficult to ignore. These signs include:
Popping sound as the ligament tears
Immediate pain, swelling and instability
Increasing swelling and pain following the injury
Limited range of motion of the knee
Tenderness at the site
Inability to walk
Patients who are suspected of having ACL injuries should obtain medical attention immediately to avoid further joint damage.
Diagnosis of an ACL Injury
An ACL injury can frequently be diagnosed by physical examination alone. When the ACL has torn, the physician can frequently feel the increased movement of the tibia upon the femur during the physical examination. There may be significant swelling of the knee as well if the injury has occurred recently. To confirm the diagnosis of ACL injury, X-rays or MRI exam may be ordered by your physician.
Treatment for an ACL Injury
Patients who suffer ACL injuries must use crutches and possibly knee braces during the early stages of recovery after the injury. The knee may feel weak and unstable during walking, thus crutches will provide support and balance. Depending on the severity of the injury, surgery may or may not be necessary. While not all ACL injuries require surgery, leaving the ligament torn or damaged puts the patient at risk for recurring episodes of knee instability. It may also increase the likelihood of developing tissue damage or arthritis over time. For athletes who want to return to high-risk sports, surgical reconstruction is usually necessary.
ACL Ligament tears cannot be repaired by simple reattachment. When the ACL tears, there is not much tissue left to work with. Thus, ACL surgery is typically call ACL Reconstruction, meaning a new ACL must be built. This requires the use of a graft. A graft is a piece of tissue from either the patient’s own body (Autograft) or cadaver graft (Allograft). There are risks and benefits of both graft choices that your surgeon will discuss with you.
Physical therapy is always necessary to restore strength, function and stability to the knee, whether or not the patient undergoes surgery.
Anterior Cruciate Ligament Reconstruction
The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments in the knee. Running diagonally through the middle of the joint, the ACL works in conjunction with three other ligaments to connect the femur (upper leg bone) to the tibia (the larger of the two lower leg bones). ACL injuries occur most commonly in athletes as a result of direct contact or an awkward fall. About half of ACL injuries are also accompanied by damage to the meniscus, cartilage, bone or other ligaments in the knee, any of which may complicate the repair process.
The ACL Reconstruction Procedure
ACL reconstruction is usually not performed until several weeks after the injury, when swelling and inflammation have been reduced. This will reduce the risk of stiffness after the surgery. In most cases, an ACL reconstruction is necessary because there has been complete tearing of the ligament. Simply reconnecting the torn ends of the ACL will not repair it. The torn ligament has to be completely removed and replaced with a reconstruction procedure using a graft.
Most commonly, the graft used is an autograft, harvested from patient’s own body, such as the tendon of the kneecap (patellar tendon) or the hamstring tendons. In other procedures, allograft tissue, taken from a donor is used. The graft is secured to the femur bone and tibia bone with a button or screw. This procedure is performed under general anesthesia on an outpatient basis.
Benefits of Arthroscopic ACL Reconstruction
This procedure can be performed using arthroscopic techniques, which involve creating a few small incisions in the knee, into which a camera and tiny surgical instruments are inserted. Saline is injected into the knee to allow for more operating space. The surgeon performs the reconstruction while viewing the interior of the knee on a video monitor for more precise results. Arthroscopy offers patients a less invasive procedure with less scarring, less pain, less bleeding and a shorter recovery time.
Risks of ACL Reconstruction Surgery
Although considered a very safe procedure, there are certain risks associated with ACL reconstruction surgery, including graft failure, postoperative stiffness, continued instability, or post traumatic arthritis, to name a few. The risks associated with any surgical procedure, such as infection, blood clots, excessive bleeding, breathing difficulties, and adverse reactions to medication or anesthesia also apply.
Recovery from ACL Reconstruction Surgery
Following ACL reconstruction surgery, patients can return home after a few hours of medical observation. Patients will likely experience pain, bruising and swelling after surgery, which can be managed through prescription pain medication. Individual recovery varies depending on the type of procedure performed and the condition of the individual patient.
Physical therapy begins right after surgery, and normally continues for several months to help patients return to activity with their reconstructed knee. In order to achieve the most effective results from surgery, patients must commit to a long-term rehabilitation program. The ACL surgical reconstruction is typically successful, providing long-term stability of the knee joint. After completion, most patients experience effective pain relief and improved knee function.