Where is the anterior cruciate ligament located and what is its function?
The anterior cruciate ligament (ACL) is located in the center of the knee. Its proximal insertion is on the medial aspect of the external femoral condyle and its distal insertion is on the anterior aspect of the tibia. Its main function is to limit the anterior translation of the tibia with respect to the femur and also the internal rotation of the tibia in the last degrees of extension of the knee.
What disorders can it suffer from?
The main disorder affecting the ACL is rupture. It usually occurs in an indirect trauma in which the foot remains fixed on the ground (the cleats are firmly nailed during the practice of soccer or the fixation of a ski does not jump properly) and the body continues to rotate producing an excessive rotation of the knee that finally breaks the ligament. The rupture produces the phenomenon called “pivot shift”, which the patient refers to as a failure of the knee that prevents him/her from recovering his/her level of sports activity due to pain, lack of stability and swelling.
Occasionally partial ligament injuries occur. In these cases, if knee stability is maintained, conservative treatment can be considered. The stability that contributes the ACL to the knee protects the meniscus, so that in chronic injuries it is frequent that a partial meniscus rupture takes place. If there is bone edema or associated meniscal lesions, ligament reconstruction and treatment should be performed. In cases where there is a symptomatic partial ligament injury without associated injuries, a partial reconstruction can be performed, with very good results since part of the tissue has not been damaged.
In which cases should we proceed to reconstruction? Is it always necessary?
In young and active patients, ligament reconstruction is the best possible treatment. Non-surgical treatment may result in a high risk of failure episodes that will make sports practice impossible. In addition, delaying treatment in patients with instability increases the risk of secondary injuries that worsen the prognosis.
In cases of older, sedentary patients who do not present episodes of failure in their daily activities, non-surgical treatment may be considered, but they will have to limit their activities significantly.
What does the operation consist of?
The procedure consists of ACL reconstruction. Attempts to repair the ligament by suturing the torn ends are unsuccessful, a new ligament must be made. For it different plastias or tissues are used that can be obtained from the same patient (autografts) or from a donor (allografts). Tunnels are made in the femur or tibia and the ends are fixed with different devices. The current trend is to perform anatomical reconstructions, trying to faithfully reproduce the anatomy of the native ACL.
How long will it take for the patient to recover completely?
Recovery is usually rapid. Crutches are recommended for 3-4 weeks and prophylaxis with subcutaneous injections of heparin for 10-15 days. In some cases where it is necessary to limit the mobility of the knee, a knee orthosis may be used. Most patients will be able to lead a normal life, without physical demands, after about 6 weeks.
For the reincorporation to the sport activity it is necessary more time. After the application of the plasty a phase of “ligamentization” of the tissue begins, the duration of which is marked by the biochemical and histological processes that are occurring in the new ligament. During this period of time the resistance of the plasty decreases with respect to the initial one, just after the surgery. This is important to keep in mind since the process is independent of the recovery of mobility and the patient’s subjective feeling of his or her knee. Prematurely subjecting the plasty to mechanical stresses for which it is not prepared will lead to early failures that will necessitate a second surgery. This will present greater complications and worse functional results. You have to do it once, and do it right.