ACL Tear Repair

The anterior cruciate ligament (ACL) is one of the four major ligaments of the knee. Ligaments are strong, dense structures made of connective tissues that help stabilize a joint. The ACL is an important part of your knee, stabilizing the joint by connecting the femur and the tibia just below your kneecap.

What are the causes and symptoms?

ACL tears most notably occur in athletes participating in cutting and pivoting sports such as basketball, football, soccer, and skiing. At the time of an ACL injury, you'll likely feel a "pop" or a tearing sensation and then experience swelling in the impacted knee.

In some patients, ACL injuries are more subtle and may not be noticed until the knee feels unstable or just "not right" when doing activities or sports. The most common injury associated with ACL tears is a meniscus tear.

ACL Tears in Females

ACL injuries are much more common in female athletes. There are multiple reasons for this including bony anatomy, hormonal differences, muscular balance and the way females perform certain sports. Of these factors, the ones we can potentially change are muscular balance and the techniques behind the sporting actions.

Females tend to cut and jump with their knees only slightly bent, which can predispose them to ACL injury. The hamstring to quadriceps strength ratio is also different from males.

Researchers have shown that strengthening exercises and plyometric programs aimed at changing these factors can prevent ACL injuries.

How are ACL injuries treated?

ACL strains and partial tears can sometimes be treated with physical therapy and muscle strengthening.

However, most complete tears require surgery in active patients. The surgery is done mostly arthroscopically, with a camera and requires only a few small incisions. The ACL is reconstructed using a tendon graft from the patient or a cadaver. In some rare cases, the ACL can be repaired.

ACL Reconstruction Grafts

There are several options when it comes to ACL reconstruction, and the option your surgeon recommends will depend on your individual case and lifestyle.

Regardless, your surgeon will take the time to explain your ACL reconstruction options in order to determine the option that is right for you. Available graft options include the following:

Patellar Tendon Graft

The patellar tendon is a flat, broad tendon with bone attached to both ends. The central third of the tendon can be used along with bone plugs from the patella and tibia for reconstruction of the ACL.

This graft has a very long track record and has been considered the gold standard for ACL reconstruction.

This tendon is stiff and the bone on both ends allows for rigid fixation and early healing.

Potential downside of a patella tendon graft is there is a higher risk of knee pain, especially with kneeling. Plus, some long-term studies show possible increased risk of arthritis compared to hamstring grafts.

Hamstring Tendon Graft

The hamstring tendons can also be used as a graft for ACL reconstruction. There are four hamstring tendons in the body, but typically two hamstring tendons are used for the ACL graft. Most often, these two tendons are doubled over to create a four-stranded graft.

Unlike the patellar tendon graft, the hamstring graft does not involve bone. While the graft itself is very strong, there is no bone-to-bone healing. This may allow for more stretching out over time, and there may be a slightly higher risk of graft failure in the long term.

Some patients also report weakness in their hamstrings following tendon harvest. This flexion weakness can be an issue for certain sports, especially in females (who have relatively weaker hamstrings compared to quadriceps). Hamstring grafts have several potential advantages including:

Smaller incisions
Less anterior knee pain
Less likely to develop patellar tendonitis

Some research shows that patients have less pain in their knees than patients who had patellar tendon grafts but a higher risk of laxity or graft failure.

Quadricep Tendon Grafts

Historically, the quadricep tendon has been used less frequently than hamstring or patella tendon grafts, but it is being used more in recent years. The quadricep is thicker than the patella tendon and has more collagen. It has less propensity to stretch than a hamstring tendon does and also does not cause flexion weakness as a hamstring graft might.

Patients initially can have quad weakness, but this resolves over time. There is also lower risk of anterior knee pain than a patella tendon graft. One downside is that a quadricep tendon graft does require an additional incision just above the kneecap.

Allograft

Allograft tissue is another option for ACL reconstruction. This avoids taking any additional tissue from your other tendons and the potential downsides of doing that. There is no tissue matching required for ACL grafts.

The downside of allograft tissue is the risk of disease transmission (though this is extremely rare), longer time for graft incorporation and higher failure rate, especially in younger patients. This type of graft is used most commonly in patients over the age of 40.

BEAR Implant

The BEAR Implant is the first FDA-approved medical technology to enable healing of a torn ACL. This new approach is a shift from reconstruction using a graft, which is the current standard of care.

There are a number of advantages to restoring a ligament instead of replacing it, and this exciting medical technology is the first to enable the body to heal its own torn ACL while maintaining the natural knee anatomy.