The Anterior Cruciate Ligament (ACL) connects the tibia (shinbone) to the femur (thighbone). The ACL is in the center of the knee - it crosses the Posterior Cruciate Ligament (PCL) - hence the name "cruciate". It is deep inside the knee joint and provides almost 90% of the stability, by preventing the tibia (shin) from moving forward on the femur (thigh). There are approximately 200,000 ACL injuries per year in the United States. Currently, there are approximately 75,000 surgical ACL reconstructions per year.

There has been a dramatic increase in the number of females who suffer an ACL tear. This is in part due to the rise in women's athletics but studies have shown that female athletes are more likely to suffer this injury when compared to their male counterparts. It is uncertain why this is the case, although one theory suggests females are at higher risk because of differences in training intensity. More evidence now suggests that there may be a difference in the anatomy of the female knee; the female ligament may not be as strong due to the effects of the female hormone estrogen. These factors may lead to a higher risk of ACL injury for the female athlete.

Risk Factors

• Female
• Poor Jumping and Landing Techniques
• Muscle Weakness
• Previous ACL Injuries
• High Demand Sports like Football, Skiing, Rugby

Injuries to the ACL may be the result of high-energy injuries or more commonly a result of a non-contact injury. In the case of non-contact injuries a patient will usually experience a "pop" or giving way of the knee while changing direction, cutting or landing from a jump. The patient is unable to return to play and experiences swelling within a few hours. Initially the knee becomes painful and swollen, but within a week most patients can weight bear on the knee but have a feeling of instability when changing directions. Some people will be able to function without any problem after they get over the initial injury, especially if they only had a partial tear. The majority however will notice instability - the feeling that their lower leg is shifting forward. For some this will be a minor nuisance but for others, especially those who participate in sports, it can be a significant disability. Often there is accompanying injury to other ligaments, the meniscal knee cartilage and even the articular cartilage. Most ACL ruptures may be diagnosed through a careful history coupled with a good physical exam.

Symptoms

• Knee Giving Way
• Pain in Knee
• Popping Sensation
• Swelling
• Bruised Knee
• Difficulty Moving Knee

Exam
A complete exam by a sportsmedicine physician is important to determine the extent of the injury. The physician will perform several tests to check the stability and integrity of the knees ligaments. Swelling, bruising, and the range of motion available in the knee will also be noted. The physician may drain fluid from the knee. This not only gives relief from the swelling but provides useful information to your doctor. If there is blood found when draining the knee, there is about a 70% chance it represents a torn ACL. X-rays of the knee are done to rule out a fracture. Ligaments and tendons do not show up on x-rays, but bleeding into the joint also occurs when a fracture is present or when portions of the joint surface are chipped off. Magnetic Resonance Imaging (MRI) can be used to clarify a tear as well as display additional meniscal or ligament problems.

Ruptured ACL as visualized by the inconsistency in the dark fibers of the ligament

Treatment:

Rehabilitation is important whether you plan on getting surgery or not. The first priority is to decrease the pain and swelling. This can be done with rest, ice, elevation, compression and anti-inflammatory medication. Secondly it is imperative to get the motion in your knee back as quickly as possible to prevent any permanent loss of motion. If major swelling is present it may be helpful for an experienced physician to remove fluid by needle aspiration.

Once a diagnosis of ACL rupture is established, the decision to reconstruct the ligament must be determined on an individual basis. It should be noted that attempts at repair of a cruciate ligament have not proven successful. Patients that are active and enjoy activities involving running, cutting, and pivoting are good candidates for the only successful surgical concept (e.g. a reconstructive procedure). If there is an associated meniscus injury reconstruction of the ACL may improve the chances of a successful repair and prevention of future tears. The goal of the surgical procedure is to restore stability to the knee and allow the patient a full return to pervious activities. In patients who are older or lead a more sedentary lifestyle reconstruction may not be necessary but is not contraindicated. These decisions should only be made after an evaluation and discussion with an experienced Orthopedic Surgeon.

Also important in making decisions about which way the knee should be treated is the growing realization by orthopedic surgeons that long term instability leads to arthritis of the knee. Many orthopedic surgeons feel that by treating the instability and performing a reconstruction of the ligament, the risk of developing wear and tear arthritis in the knee can be reduced.

Reconstructive surgery should not be performed until the injury inflammation is eliminated. This usually occurs three weeks or more from the date of the injury. Patients should attend physical therapy to regain full range of motion, strengthen the surrounding muscles, become knowledgeable of the exercises required after surgery, and then make a decision concerning reconstructive surgery.

Surgery

Surgery for ACL injuries is extremely specialized and should only be performed by a surgeon who is experienced in this type of injury. The techniques continue to change and cutting edge experience offers a better opportunity for a good result.

It should be noted that ACL reconstruction means creating a new ligament out of a tendon from another location in the patient's knee or using cadaver tissue. There are three popular choices:

Autograft- this refers to using the patient's own tissue as a source of the replacement ligament. This is the most popular choice for this surgery. Bone-Patella-Bone - This technique has been utilized for the longest period of time in the largest number of patients and is considered the gold standard for ACL reconstruction. In this procedure a small center portion of the Patellar Tendon along with part of the upper and lower bony connection is used. The bone-patellar tendon-bone graft is then tunneled from the tibia to the femur. The graft is held in position using screws in the femur and the tibia. The advantages are a strong graft with bone attachments at each end that allows the graft to be fixed very solidly at the time of surgery. This procedure allows rapid rehabilitation with little need for a brace or crutches beyond 1 week. The negative of this technique is potential irritation of the kneecap.

Gracilis & Semitendinosis Tendon
Another common Auto-graft is to combine two muscle tendons that attach to the tibia just below the knee joint: the gracilis and the semitendinosis tendons. Studies have shown that these two tendons can be removed without a major effect on the strength of the leg. This technique is recommended for patients who for whatever reason are not a candidate for usage of the patella tendon. This graft is braided and passed through a tunnel from the tibia to the femur. Once again the graft can be secured using screws or other fixation devices. But the security of fixation is not as secure as the bone-patella-bone technique.

Allograft- This means using tissue from a cadaver. This is an option where multiple ligaments are injured and additional tissue is needed for surgery, for revision cases where the patient's own patella tendon has already been utilized, or the need to maintain the anatomy as is. The Allograft has proved quite successful but tends to be somewhat less strong than Autografts.

The choice of graft can be determined by a decision between the physician and patient when the benefits and detriments of each are fully understood. It is also important to understand that varying arthroscopic assist techniques are available.

Following reconstruction a strict protocol of therapy is followed to restore strength and motion in the leg. Physical therapy is crucial for obtaining the most successful outcome. Physical therapy can last 2-6 months depending on the person and their level of activity and their wish to return to sports.