What is an anterior cruciate ligament rupture?

The rupture of the anterior cruciate ligament (ACL) is one of the most common sports injuries to the knee but can also result from a fall, collision, or accident.

Athletes participating in sports such as football (soccer), skiing, basketball, volleyball, handball, and generally contact sports or sports involving sudden changes of direction are prone to ACL injuries.

What are the injury mechanisms?

The anterior cruciate ligament (ACL), along with the posterior cruciate ligament, the collateral ligaments, and the thigh muscles, are the main stabilizing elements of the knee. The ACL controls the joint’s movements, protects the knee from hyperextension, and prevents the forward displacement of the tibia relative to the femur.

ACL rupture occurs through the following mechanisms:

• During sudden changes in direction by the athlete
• When the athlete suddenly stops or slows down
• During an abnormal landing after a jump or fall
• From a direct blow, usually during a collision with another player

Several studies have shown that female athletes have a higher rate of ACL rupture compared to male athletes in the same sport. Possible causes include anatomical differences concerning the pelvis and different alignment of the lower limbs, differences in muscle strength and neuromuscular control, increased ligament laxity, and the influence of female hormones (estrogens) on the ligaments.

Can ACL rupture be prevented?

ACL ruptures can be largely prevented, especially in amateur athletes. Special training programs have been designed to prevent ACL injuries, focusing on proper neuromuscular control of the knee. These programs include plyometric exercises, balance exercises, and strengthening and stability exercises, which should be performed consistently and not only during the athlete’s preparation period.

Clinical presentation of ACL rupture

During the rupture of the ACL, the patient may often feel or hear the ligament “snap” and immediately feel the knee giving way. This is usually accompanied by pain and swelling (hemarthrosis—blood accumulation in the joint) which becomes noticeable within the first 24 hours. There may also be a reduced range of motion.

Gradually, after a few weeks, the hemarthrosis is absorbed, pain decreases, and if the patient does not participate in sports, they may return to daily activities without significant discomfort.

However, knee instability usually persists, and for an athlete wishing to return quickly to sports after the acute phase, this instability can cause injury to other knee structures such as the articular cartilage and menisci (meniscal tears).

How is the diagnosis made?

Diagnosis is based on a detailed injury history, the mechanism of injury, symptoms, and clinical examination. The orthopedic doctor will test knee stability with special clinical tests.

Knee X-rays, although they do not show soft tissue injuries, may reveal associated fractures.

Diagnosis confirmation is made with MRI, which also reveals any concurrent injuries. In about half of cases with ACL rupture, there are also injuries to other knee structures such as the menisci, articular cartilage, or other ligaments.

What is the treatment for ACL rupture?

In the acute phase, treatment includes:

• Rest to partial weight bearing with crutches
• Cryotherapy (ice treatment)
• Compression bandages
• Elevation of the limb

Afterwards, the type of treatment—conservative or surgical—depends on the patient’s needs:

• Age
• Daily activity requirements
• Type of work
• Sports activities
• Any associated injuries
• Degree of instability caused by the rupture

Thus, an active person or a young athlete wishing to continue sports is more likely to need surgery compared to a less active, usually older person who does not play sports and can return to daily activities symptom-free with conservative treatment.

How is conservative treatment handled?

After the acute phase, conservative treatment initially involves physical therapy to reduce pain and swelling. Then, a comprehensive rehabilitation program with strengthening and proprioceptive (balance) exercises under the guidance of a specialized physiotherapist.

If the patient continues to feel instability or sustains a new injury after a full rehabilitation program, surgical treatment is recommended.

Clinical studies show that patients with untreated ACL rupture develop knee osteoarthritis much earlier than those without ACL injury.

How is surgical treatment done?

The goal of surgery is to stabilize the knee and prevent secondary damage (meniscal tears and cartilage injury) caused by instability. Also, the ACL has low healing ability compared to other knee ligaments and does not heal by itself after injury.

ACL reconstruction with graft

Surgical treatment involves reconstruction (replacement) or ligamentoplasty of the ruptured ACL, usually using a graft from the patient (autologous biological graft). The surgery is performed arthroscopically, without opening the knee joint, through small incisions of a few millimeters.

Grafts used include tendons of the hamstring muscles, part of the patellar tendon, or less commonly, part of the quadriceps tendon. In special cases with multiple ligament injuries, synthetic grafts may be used. Each type of graft has advantages and disadvantages. A detailed discussion between the patient and the orthopedic surgeon helps choose the best graft.

In recent years, there have been significant advances in ACL reconstruction techniques. Various ligamentoplasty methods exist, such as single-bundle or double-bundle techniques, as well as graft fixation methods.

During surgery, the surgeon can also repair any associated injuries found, such as meniscal or cartilage tears.

Arthroscopy is done under a combination of regional and light general anesthesia depending on the patient’s medical history. A few hours after surgery, the patient can get up with the help of a functional brace or crutches and return home.

Biological treatments with stem cells are increasingly used to enhance and accelerate graft healing and integration.

ACL repair (suturing)

Older studies on suturing the torn ligament showed poor results.

However, in the last 5 years, in selected cases with specific indications, a technique called DIS (Dynamic Intraligamentary Stabilization) with the Ligamys system is being tested. This method preserves the ACL but requires a second surgery to remove fixation materials after about 6 months.

Studies on this technique are still ongoing.

ACL rupture & postoperative rehabilitation

Postoperative rehabilitation is an integral and very important part of the patient’s return to their activities. Physical therapy initially focuses on regaining the full range of motion of the knee joint and preventing further loss of muscle mass. Subsequently, it includes strengthening exercises specifically designed to protect the new ligament. In the final phase, specialized exercises aim to reintegrate the patient into their sport.

Although the return to daily activities is rapid, full return to intense athletic activities usually occurs after six months.