Tear of anterior cruciate ligament（ACL）
Anterior cruciate ligament rupture occurs spontaneously even in non-contact sports.
Anterior cruciate ligament (ACL) rupture, the most severe injury of sports injury of the knee, can affect athletic activities. It happens commonly in contact sports, and treatment is prolonged. Please be careful that halfway treatment induces rather prolonged treatment terms and after the treatment it does not necessarily result in a better prognosis.
Cause and mechanism of onset
The ACL runs in two bundles from the lateral femur to the medial tibia within the knee joint. The ACL functions as a stopper for sports activities to not break the knee when the person takes motion such as jump, landing, dash, stop, cut, or twist. ACL stabilizes the knee joint when anterior mobility of the lower leg, internal rotation of the lower leg (torsion), and pivoting movement are conducted.
Cause of the injury
It is more likely to occur in contact sports that tackle to the knee. The injury sometimes occurs when the athlete jumps and lands such as in a non-contact sport like basketball or volleyball, when a pivot is forced, or when the one slips.
Sports likely to cause the injury and gender differences
These sports include American football, rugby (e.g., during external and posterior tackling), skiing, snowboarding (where the board is fixed and the knee is forced to rotate), judo, basketball (where people are hit when the jump is landed), and volleyball (self-harm due to slip). The site of ligament injury may actually be changed by a tackle above the knee, below the knee, or if the foot has been secured. In volleyball and basketball women much suffer the injury.
Acute phase: Pain that starts suddenly after an injury, impaired knee movement, swollen joints or hematomas, and knee collapse (the knee does not work and falls when landing) may appear. If pain persists still after 2 to 3 weeks, meniscus injury is suspected.
In the acute phase, joint hematomas and flail joint are caused. Manual tests are positive for anterior pull-out, Rackman test (flexion position of the knee about 20 degrees), and the Pivot Shift test (N-test). MRI is the most helpful procedure. It can detect not only ACL but also other ligament injuries, meniscus injuries, hematomas, and bone injuries. Mobility of the knee joint can be checked with a telos or other instrument.
An X-ray helps check for fractures, but does not show ligaments. Arthroscopy (endoscopy) is the most useful and reliable method of diagnosis, but it is invasive as a surgical procedure, with a skin incision and anesthesia. The ACL is rarely injured alone and is often combined with medial collateral ligament injury or meniscus injury.
Photo: Arthroscopic photograph of an ACL mild injury. The ligaments are relaxed, but their morphology is preserved.
Treatment and rehabilitation
In principle, ACL reconstructive surgery is necessary when adolescent athletes maintain a high level of sports activity. Currently, surgery is usually performed by implanting the own tendon (such as a semitendinosus tendon or a patellar tendon with a bone). Because the ACL is present in the knee joint, it is a negative factor that when collateral blood flow from other parts of the body is poor and ruptured, direct suturing does not restore blood flow, and the tendon is difficult to agglutinate. Consequently, ligament reconstruction with tendon grafting is the mainstream of surgery. Reconstruction with prosthetic ligament, which is previously prevalent, is now less common.
Immobilization with a cast or brace for a long time from the initial stage is a way of the conservative treatments. However, it is important to understand that, with conservative treatment, it is difficult to restore the function of the ACL itself due to loosening of the tendon, and that the purpose of treatment is to restore ADL (activities of daily living), maintain and strengthen muscle strength around the knee, and maintain competitive performance. Early in the injury, it is recommended that immobilizing the joints or the icing measurements.
Check points during training are as follows:
(1) whether the knees do not collapse while walking in daily life,
(2) Availability of running,
(3) Availability of climbing and descending on stairs,
(4) Availability of jumping with both legs,
(5) Availability of dashing, and
(6) Availability of jumping with a leg.
If knee collapse does not recur during exercise or skiing after treatment or if it occurs, the knee should be re-examined for surgical treatment. There is a risk of meniscus injury or articular cartilage injury.
(1) Two to three weeks after surgery (if a patient has conservative treatment, after the injury), one begins full weight-bearing walking with an orthosis. Start with less weight-bearing, underwater walking, flutter kick, crawl, flat swimming, and aerobics.
(2) Once no knee pain or swelling has been confirmed after doing the exercise listed above, gradually stressing exercises is recommended such as running, stepping jumps, calf raise, leg curls, and uncoordinated leg movements with no load (hip joint flexion, knee flexion, ankle dorsiflexion, extension, plantar flexion).
(3) Finally, a half squat, balance board, sliding, calf raise. and trampoline are used to re-educate the sense of balance around the knee.
(4) If it is confirmed that there is no problem from the exercises above, please perform more active sports gradually. However, each performance requires a monthly training period.
The period to return to sports varies but it is said to take at least 6 months, but it actually takes up to 8 months and generally more than 1 year. In many cases, joint loosening persists with halfway treatment and rehabilitation.