Anterior Cruciate Ligament Reconstruction: Surgery on the Anterior Cruciate Ligament – Tendon Tear, ACL Tear, Rehabilitation & ACL Rupture

The cruciate ligaments are located at the center of the knee joint. They connect the thigh bone (femur) to the shin bone (tibia) and ensure stable mobility of the joint. Other ligaments, as well as the muscles surrounding the knee, support the anterior and posterior cruciate ligaments in this function.

Cruciate ligament tears most commonly affect the anterior cruciate ligament (ACL). The injury is often the result of sports-related accidents. The risk of sports injuries is highest in sports such as

• soccer and other ball sports,
• skiing,
• tennis,
• kitesurfing,
• trampoline jumping.

These activities require sudden braking and acceleration combined with complex knee movements.

The menisci of the knee joint also act as shock-absorbing cartilage discs that cushion stress, stabilize the joint surfaces, and protect the cartilage from wear and tear.

The posterior cruciate ligament, on the other hand, tears much less frequently. Such injuries result from direct force applied to a bent knee, for example in martial arts or in traffic accidents.

The location of the cruciate ligaments in the knee joint © Henrie | AdobeStock

Cruciate ligament reconstruction is the most common surgical procedure for restoring or reconstructing a torn cruciate ligament. During the procedure, the surgeon removes the non-functional, torn portions of the cruciate ligament from the knee joint. The surgeon then replaces it with a graft (cruciate ligament replacement).

Generally, the graft consists of

• a tendon from the patient’s own body,
• donor material, or
• synthetic replacement material

.

Today, almost all surgeries rely on autologous grafts. In most cases, one of these three autologous tendons or tendon segments is used:

• the semitendinosus tendon, which is part of the posterior thigh flexor muscles: currently the standard choice for non-professional athletes
• a segment of the quadriceps tendon from the large thigh muscle
• a segment of the patellar tendon, located below the kneecap

The function of the harvested semitendinosus tendon is compensated for by neighboring tendons.

In general, the muscles surrounding the knee can compensate for a torn cruciate ligament to a greater or lesser extent. Once the acute pain and swelling have subsided, the injured knee is typically mobile again and can bear weight.

However, the tear often leads to abnormal instability of the knee joint. The patient notices this as well.

If left untreated, a cruciate ligament tear also leads to improper loading of the knee. Over time, this frequently results in secondary injuries or knee osteoarthritis. Osteoarthritis refers to the painful wear and tear of a joint. In its late stages, osteoarthritis is a common reason for knee replacement surgery.

A torn cruciate ligament cannot grow back together and heal on its own. To prevent the complications described above, cruciate ligament reconstruction is often unavoidable.

In general, cruciate ligament surgery is performed several weeks to months after the injury. By then, the swelling in the knee caused by the injury has subsided, and the joint has regained its full range of motion.

During this time, the patient should exercise the joint, for example through physical therapy. This helps restore normal mobility and muscle strength and teaches movement patterns that are gentle on the joint. This also has a positive effect on the healing process following knee surgery. 

Sometimes, especially in older patients, this form of conservative therapy is sufficient on its own.

Cruciate ligament reconstruction is recommended if:

• there is a high demand for mobility due to sports or occupational activities,
• the patient is having difficulty coping with the injury,
• the knee joint shows significant instability under full weight-bearing, or
• other structures of the joint are injured.

Even after attempting conservative treatment, it is not too late for surgery.

Minimally invasive knee arthroscopy is the most common and least invasive procedure for cruciate ligament reconstruction. The procedure typically lasts between 45 and 90 minutes.

General anesthesia or spinal anesthesia may be used to control pain during the operation. The latter blocks pain sensation in the lower half of the body.

The knee surgery is performed using an arthroscope. This is a thin camera that the surgeon inserts into the joint through small incisions. The image from inside the joint is then magnified and displayed on a screen.

Using the arthroscope, the surgeon first assesses the extent of the damage to the cruciate ligament. The surgeon also checks for any associated injuries. If such injuries are identified, they are treated—for example, by suturing or partially removing damaged meniscus tissue, or through cartilage surgery.

The surgical team then removes the tendon intended for use as a graft through an incision approximately 3–4 cm long. Depending on the surgical technique, this is usually the tendon of the semitendinosus muscle. It is then prepared for transplantation.

The tendon is then transplanted. Using the arthroscope’s fine surgical instruments, the surgeon first removes the remnants of the torn cruciate ligament. The surgeon leaves the ligament’s attachment sites on the bones in place. Here, he drills small holes in the femur and tibia. The graft is then reattached through these holes.

Finally, the surgeon may insert a small drainage tube. This drains fluid from the operated joint over the next few hours. The surgeon then closes the surgical incisions with sutures.

Immediately after surgery, you will remain in the hospital for one to two days. During this time, with the support of the hospital staff, you will make your first brief attempts to stand up and walk using crutches. It is important to keep the joint immobilized and in a straight position during the first 24 hours. This prevents the newly transplanted tendon from shortening.

To reduce the risk of developing a thrombosis, you should resume physical activity as soon as possible. Thromboses are blockages in blood vessels caused by small blood clots. They can form if you remain inactive for too long. For the same reason, you’ll need to take blood-thinning medication by injection immediately after surgery and, if necessary, wear compression stockings.

In the weeks that follow, you will gently “reactivate” your knee under close physical therapy supervision and gradually increase your activity level. During the first few weeks, you should not bend or put too much weight on it. Cooling the area, elevating the leg, and manual lymphatic drainage help reduce joint swelling.

After 4 to 6 weeks, patients are usually able to fully bend their knee. They will also no longer need walking aids.

How quickly you can resume sports varies from person to person. Physical therapists and sports medicine specialists use so-called “return-to-sports” tests to assess how much stress the operated knee can already handle. On average, athletic patients who have undergone ACL reconstruction

• can cycle on the road and swim again after six weeks,
• jog and engage in more demanding cycling after three to six months, and
• after nine to twelve months, ski, play ball sports, and practice martial arts.

Infections of the operated joint are among the most serious, though very rare, complications of ACL surgery. An infection can affect up to 0.8% of patients and, in the worst case, destroy the joint.

It is also rare for patients to develop scar tissue in the joint (arthrofibrosis) after the procedure. Scar tissue can cause the knee to stiffen. In such cases, another surgery is necessary to correct the scar tissue.

The most common complication is a re-tear of the cruciate ligament on the operated side or the opposite side (there is also an increased risk due to the knee joint giving way). This complication affects approximately 10 to 15 percent of those injured. Young and active people, in particular, are at increased risk.

The site from which the graft is harvested can also cause problems. If a patellar tendon is used as a graft, about half of the patients still experience pain 1–2 years after surgery.

According to study results, cruciate ligament reconstruction yields better outcomes than conservative treatment. However, this requires good patient cooperation. The patient must consistently build muscle strength and must not put weight on the joint too soon.

On average, patients who undergo surgery achieve a higher level of performance than those treated with physical therapy alone. Based on current research, anterior cruciate ligament replacement is strongly recommended, particularly for young (including children) and active patients. The surgery also serves to prevent secondary damage and a reduction in physical activity.

Isolated cruciate ligament tears generally have a very good prognosis. These are tears without any additional accompanying damage to the joint.

Whether ACL reconstruction can prevent or delay the later development of osteoarthritis in the injured knee is a matter of debate. Initial long-term studies following anatomical ACL reconstruction show that surgical stabilization of the joint has a positive effect in this regard.