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Sun 1 Jul 2007 12:00 AM

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Preventing and treating ACL injuries

Minimally-invasive techniques have revolutionised ACL repair, but patients are better off learning to prevent injury through proper training techniques.

Injury to the anterior cruciate ligament (ACL), a key knee stabiliser, is common in the Gulf region, and the incidence of such injuries is thought to be even higher in the Middle East than in North America. The precise reason for this is unknown, but one factor may be the widespread popularity of football in the Gulf region.

Football is associated with a high incidence of ACL injuries because players routinely jump, twist, and change direction suddenly - movements that can strain or tear the ligament that runs from the back of the femur to the front of the tibia. Internationally, other sports associated with a high incidence of ACL injuries include basketball, volleyball, handball, skiing, gymnastics, rugby, and lacrosse.

Generally, it is best to try to avoid sustaining such an injury because of the lengthy rehabilitation time and potential long-term risk of developing osteoarthritis in the joint, says Dr. James Herndon, an orthopaedic surgeon at the Massachusetts General Hospital and a professor of orthopaedic surgery at Harvard Medical School in Boston, Mass.

The best way to prevent ACL injury is through training methods that combine jumping, deceleration training, and exercises that help the athlete progressively prepare for the stresses typically encountered during sports participation. These programs are particularly important for women, who are at much higher risk for ACL injury than men, he adds.

For patients who sustain an ACL tear, reconstruction is an increasingly viable option. Thanks to the introduction of arthroscopic techniques it is now possible for surgeons to reconstruct the ACL with a graft from the patient's own body or a cadaver through a small incision, resulting in a shorter, less painful recovery. In this In Practice, Herndon, who is also Emeritus Chairman of the Partners Department of Orthopaedic Surgery and Program Director of the Harvard Combined Orthopaedic Residency Program, discusses the latest methods of preventing and treating ACL injuries and offers advice on counselling patients who may be considering ACL reconstruction.

ACL injuries in women

As more women participate in sports ACL injuries in female athletes have become an epidemic problem in the U.S. Studies suggest that female athletes are four to six times more likely to sustain an ACL injury than their male counterparts.

Researchers have explored several possible explanations for the disparity. Theories point to biomechanical factors, hormonal effects, environmental factors, and anatomical differences, such as knee alignment, ligament laxity, muscular imbalances, and the size of the ACL and the intercondylar notch (the cavity surrounding the ACL).

While interesting, many of these observations have not led to obvious methods for injury prevention. The biomechanical explanations, however, have led to new methods of neuromuscular training programs that have been shown to help women protect their ACL against tearing, says Herndon.

Over the last five years, studies have shown that when women jump they tend to land on a flat foot rather than their toes and use their quadriceps more than male athletes, he explains.

In addition, men tend to land with their knees bent, but women land with their knees straight, which puts more pressure on the ligament. In addition, women tend to overemphasise their quadriceps muscles, vs. their hamstrings when changing direction.

New training methods teach women safer jumping skills, such as landing with their knees bent instead of straight. They also teach women to practice crouching and bending at the knees and hips when they turn and pivot, and do exercises that stretch and strengthen the hamstrings.

Herndon suggests making sure that all female patient athletes work with a strength and conditioning specialist, sports medicine physician, or physical therapist who is fully versed in the latest techniques. Such training should be practiced regularly year-round.

Diagnosing ACL injuries

Accurately diagnosing and treating an injured ACL is extremely important, because failing to do so could lead the cushioning cartilage (the meniscus) in the knee to become seriously damaged. Without the meniscus the femur and tibia can rub against one another causing further damage.

Most ACL injuries occur in non-contact situations. A hard twist or excessive pressure on the ACL tears the ligament, causing the knee to "give out" and no longer support the body. "Often the patient will feel a painful snap after landing with a straight leg, or landing and turning at the same time," says Herndon.

"Later, the knee may buckle or become painful when they move in a certain way." In some situations the knee may collapse entirely. Most of the time there will be immediate swelling.

Because of this swelling and pain, diagnosis may be difficult in the days immediately following an injury. Therefore, it may be necessary to schedule a follow-up appointment.

Diagnosis begins by asking the patient to describe how his or her knee was injured.

Usually, the patient will describe a situation in which there was no contact with another player, but instead a twisting, deceleration, or hyperextension of the knee.

Common diagnostic tests for ACL tears are the Lachman and Anterior Drawer tests, which are used to evaluate abnormal forward movement of the tibia, and the Pivot Shift test, which checks for signs of instability indicated by a shifting of the tibia on the femur.

An X-ray will not show a torn ACL, but it may be used to check for bone injury. An ACL tear may be associated with some types of bone fractures that occur to the tibia.

The most reliable test for detecting damage to the ACL is Magnetic Resource Imaging. While a physical exam can be just as effective in diagnosing a torn ACL, an MRI can help determine if there's any damage to the meniscus or other ligament or structure in the knee.

Treating ACL injuries

The problem with a torn ACL, says Herndon, is that the ligament crosses the center of the knee joint which contains synovial fluid. The fluid washes away any bleeding, precluding the normal healing process. "Even if you immobilise the knee, no clot is able to form, so primary repair doesn't happen."

As a result, although patients can choose non-surgical rehabilitation over surgical reconstruction, their activities will be limited to those that do not involve jumping, cutting, pivoting, and sudden slowing down or stopping (deceleration).

Such patients also need to undergo physical therapy exercises for a few months after the initial injury and maintain lifelong strength and stability exercises for the legs. Without such rehabilitation, they risk knee stiffness and instability.

Patients who decide not to undergo surgery can decide to do so later - especially if knee instability causes damage to the cartilage and other parts of the knee.

Generally, patients should consider reconstructive surgery if their knee is functionally unstable, their injury prevents them from participating in activities they deem important, or if there's damage to the meniscus, says Herndon.

It's important to preserve the meniscus whenever possible in order to avoid the development of arthritis. If the meniscus is repaired without reconstructing the ACL, the repair has a much higher failure rate. In addition, if the meniscus is torn and needs to be trimmed, the knee may become even more unstable, often requiring ACL reconstruction to regain stability.

It is a good idea to wait until the pain and swelling from the initial injury have diminished, as rushing surgery may result in a stiff knee.

In addition, beginning therapeutic exercise before surgery can potentially decrease post-surgical rehabilitation time. There is no disadvantage to waiting.

Reconstructive surgery

Surgical treatment involves reconstructing the ACL by replacing it with another tendon from the patient's body (autograft) or from a cadaver (allograft).

Autografts typically come from the patellar tendon or hamstring tendon. Some research has shown small differences in outcomes of patellar tendon grafts and hamstring grafts, but Herndon reports that the data is not conclusive. "Long-term results show very little difference," he says. Synthetic grafts and supplemental grafts show no advantage over biological grafts and have a high failure rate.

ACL surgery is technically demanding and is usually performed by an orthopaedic surgeon using arthroscopic techniques. Patients should find a surgeon who performs the procedure often, suggests Herndon, because if the graft is not in close proximity to the actual location of the ACL the patient's range of motion may be limited.


It typically takes six to nine months of physical therapy and strengthening exercises before a patient will be able to return to his or her previous level of activity.

Herndon suggests helping patients through this demanding period by first making sure they know what to expect and are motivated enough to complete the rehabilitation program. And as they go through the process, he advises, it also may help to remind them not to get discouraged.

"It's not like getting your appendix out or a tooth pulled," he says. "You have to do a lot of rehabilitation to build up the muscles and the motion." In the end, if they stay the course, there's good news: Eventually, the grafted ligament becomes as strong as or even stronger than the original ACL.

This article is provided courtesy of Harvard Medical International. © 2007 President and Fellows of Harvard College.

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