Sports Medicine Division | ACL tear diagnosis and injury prevention

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If your practice includes teen athletes, you’ve likely encountered at least one patient with an anterior cruciate ligament (ACL) injury. The incidence of ACL tears among child, teen and young adult athletes has reached near epidemic proportions: 400,000 athletes suffer a tear annually.

Primary care clinicians are often the first to detect a tear. Dennis Kramer, MD, orthopedic surgeon in Boston Children’s Hospital ACL Program, weighs in on your role in ACL tear diagnosis and injury prevention.

ACL tear diagnosis

Patients, often athletes between 12- and 17-years old, typically present with a non-contact twisting injury to the knee. Many report hearing or feeling a pop in the knee.

Kramer suggests looking for effusion during the physical exam by exposing both knees while the patient is resting on her back and looking carefully at the injured knee to see if there is any visible swelling on the inside of the kneecap in comparison to the other side. “You can also perform the Lachman test [the standard clinical assessment for ACL tear], but it can be difficult to perform the test because patients tend to resist the necessary knee manipulation due to knee pain, swelling and muscle spasm,” says Kramer.

The best course of action for patients with a suspicious history and swelling of the knee is to order an MRI. “Though x-rays are often negative for an ACL tear, radiologists can readily diagnosis the injury on an MRI.”

Tear management

If the MRI shows an ACL tear, the patient can be put into a simple hinged knee brace (neoprene sleeve with hinges); and should be referred to physical therapy, or pre-habilitation, to build strength and range of motion of the knee prior to surgery. They should also be referred to an orthopedic surgeon for surgical planning. Physical therapy can start before the orthopedic consultation. Patients are typically allowed to bear weight as tolerated and do not need to use crutches if they are able to walk without a limp.

Most patients who tear their ACL will require surgery. ACL reconstruction is typically preformed as a two-hour outpatient procedure about three to four weeks after the injury, which allows swelling around the knee to go down and some strength and flexibility to be regained. While patients do not need to use crutches prior to surgery, they do need to use them for a few weeks after surgery.

Recovery and return to sports

About six weeks after surgery, patients can graduate from a larger hinged knee brace (often called a Bledsoe brace) to a smaller knee brace. Most patients can begin jogging three months after surgery, and resume cutting and pivoting motions six to nine months after surgery. Many athletes also return to sports at this time. “It takes six months to a year to regain full strength in the quadriceps and hamstrings which is needed for safe sports competition,” says Kramer. Most athletes continue to wear an ACL sports brace for at least one to two years years after surgery.

Preventing re-injury

Once an athlete injures an ACL, he or she is at higher risk for re-tearing that ACL as well as injuring the other opposite ACL. “It’s hard to decrease patients’ risk for many orthopedic injuries. ACL tears are one of the major exceptions. Scientific data shows that specific ACL prevention exercises can reduce risk of re-injury,” says Kramer.

He recommends injury prevention programs, such as those offered at The Micheli Center for Sports Injury Prevention, for athletes who play high-risk sports, including soccer, lacrosse and basketball, and female athletes, who are at higher risk for ACL tears than males. Athletes who have torn an ACL can also benefit from a return-to-play program that teaches injury prevention exercises.

Learn about Boston Children’s ACL Program.

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