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June 8, 2015
The Anterior Cruciate Ligament
The anterior cruciate ligament (ACL) is one of the largest ligaments in the knee. It connects the front part of the shin to the back part of the thigh bone, and functions to keep the shin from sliding forward. To tear or rupture the ACL often results in knee instability, and patients will complain of their knee "giving way" while playing sports or participating in certain jobs that require sharp turns or pivots.
It is often ruptured by a direct blow to the knee, like in football or skiing. Often, other ligaments or cartilage are damaged at the same time. Most ACL tears, however, do not occur with a direct blow, but rather when an individual plants the foot and to stop abruptly or make a sharp turn. Interestingly, depending on the sport, women tear their ACL 2-6 times more than men. Many theories exist to explain this, but the final decision has yet to be made.
Signs of an ACL tear occur when a loud audible "pop" occurs and the knee gives way. Continue activity is usually not possible, and eventual pain and swelling increases in the knee. Walking becomes more difficult. Diagnosis often must be delayed, as examination of the knee cannot be done while the knee is so painful and swollen. MRI and arthroscopy can be used if necessary.
The most common question asked after an ACL injury is "will I need surgery?" The answer varies from person to person, and different factors influence the final decision. Those individuals who desire a high sporting activity level and engage in cutting and jumping sports are often the classic patient who needs this surgery. However, many folks lead sedentary lifestyles, may be recreational joggers, and have lower demands on their knees. Other associated injuries to the knee involving other ligaments and cartilage are factors as well that determine if surgery is needed. Older individuals typically are not candidates as well.
If surgery is not indicated, rehabilitation to regain range of motion and strengthen those muscles is paramount. Strong leg muscles stabilize the knee. A return to sports with or without a brace is allowed only after strength and balance have been regained to preinjury levels.
If surgery is performed, many options are available. Knee instability is the primary reason to perform this surgery, and different techniques exist. The "gold standard" presently is utilizing part of the patients' patellar tendon, and passing it through bone tunnels in the shin and thigh. This tendon graft is anchored solidly with large screws buried in the bone. Hamstring tendon grafts seem to be gaining popularity, and the option of using tendons from cadaver is available as well.
Rehabilitation is hard work and must be dedicated. Most folks that have this surgery are pretty tough, and push themselves to get back to their respective sports. Some of my patients are hunters, and they aren't about to give up their sheep hunts and mountain climbing to an unstable knee, so they get after it pretty good. Most people can return to desk jobs within a month, and laborers and athletes usually can return in 6-8 months. Contact sports are now being allowed by some physicians at 6 months if the patient has regained their muscular strength.
Studies show 90% of all people are able to return to their sport or work without symptoms of knee instability and give way episodes. Occasionally pain and stiffness occur, but with aggressive rehab and better surgical techniques, the outlook is bright for those injured with an ACL injury.