June 10, 2005

ACC Sports Sciences Main Page

Delmas Bolin, M.D., Ph.D.
Joe Prud'homme, M.D.
Virginia Tech Athletics

Lower leg pain is among the most common problems that recreational and competitive runners develop. Often these athletes will seek medical care and be given a diagnosis of "shin splints" or "overuse" and told to rest. Unfortunately, rest (time off from running) is something that most runners will do only when forced. Most of the time the problem is self-limited, but occasionally, the symptoms progress in duration or severity enough that the patient is no longer able to "run through it".

One such cause of prolonged leg pain with exercise is the chronic exertional compartment syndrome (CECS). The pain of CECS develops as a result of pressure imbalances between blood flowing into the muscles and the pressure of the tissue that envelopes the muscles. The muscle is surrounded by a tight tissue capsule called fascia. With exertion, blood flow to the muscle increases and the muscle swells. Even though fascia doesn't stretch much, in most people it is large enough to accommodate the swelling. Athletes, and especially endurance athletes, may develop enough swelling so that muscle arteries are squeezed enough to limit or interrupt the blood flow. The increased pressure inside the fascia may also compress nerves, resulting in numbness.

A patient's story will often suggest the diagnosis of CECS. The pain of CECS comes on with exercise, usually after 8-12 minutes, although the timing is variable. The pain grows worse as exercise continues until it is severe enough to force the athlete to stop exercising. Most commonly, the pain develops on the outside part of the shin. The pain may be accompanied by numbness or tingling in the leg and top of the foot. The affected area feels "tight" or tense and is often tender to the touch during exercise. The muscles that raise the foot at the ankle joint may be weak. A key feature of CECS is that the pain resolves with rest, usually after about 30 minutes.

There are some other causes of exertional leg pain which are similar to CECS and should be investigated. "Shin splints" and tibial stress fractures can have very similar pain patterns to CECS. Unlike CECS, patients with shin splints or late stress fractures have pain which persists even at rest. A bone scan can help diagnose and differentiate these conditions. Other common causes of leg pain include tendonitis, muscle hernias, and nerve root irritation (sciatica). Rare causes of leg pain include entrapment of one or more of the leg nerves and lower extremity blood vessel abnormalities.

The diagnosis of CECS is usually made more than a year after symptoms first appear and is most frequently mistaken at first for "shin splints." The definitive diagnosis is made by the direct measurement of the pressure in the compartment. This is accomplished by a slit catheter as shown in Figure 1 below. After the leg is numbed with local anesthetic, the needle-like slit catheter is introduced into the fascial compartment to be tested. After a sterile dressing is applied, the athlete runs on a treadmill until the symptoms develop. When the symptoms are at their worst, the slit-catheter measurements are repeated at 1 and 5 minutes after exercise. In normal muscle compartments, pressure at rest remains below the 10-12mmHg range. In CECS, post-exercise compartment pressures can rise above 30-40mmHg. If the test is positive or if there are symptoms on both sides, the other leg may be tested as well. In about one quarter of cases, if one leg is positive for CECS, the other leg will eventually develop it as well.

Once the diagnosis is established, the treatment for CECS that is likely to most rapidly return an athlete to pain free running is surgery. Common approaches to CECS including physical therapy, stretching exercises, and anti-inflammatory medicines don't usually help patients with CECS. In recreational athletes, a prolonged period of rest followed by very gradual resumption of running is sometimes successful. Unfortunately, non-surgical treatment for CECS is seldom effective in competitive athletes.

Surgical treatment involves splitting the fascia to allow the muscle more room to expand, a "Fasciotomy" (See Figure 2). The procedure is usually done one of three ways: An incision is made over the affected compartments and the fascia split (1) either under direct visualization through one large incision or two smaller ones (2) split blindly through a small incision or (3) split through a small incision using an arthroscope to allow remote visualization - the newest technique. After the surgery, most athletes return to full participation within 6-12 weeks with no residual symptoms.

As with any surgery, there can be complications. The greatest risk during surgery is damage to the superficial peroneal nerve. Such damage is usually permanent and causes numbness of the top of the foot. A recent cadaver study showed that this nerve was damaged in 10% of the specimens done using the small incision "blind' technique. A tender or ugly scar is the other main risk. Failure can also occur if the fascia is not completely released.

Although CECS cannot be prevented, there are a few measures that may offer some protection. Gradual increase in exercise intensity and duration of no more than 10% per week is the best preventative strategy for CECS - as well as for shin splints and stress fractures. Most overuse syndromes are caused by "too much, too soon". For runners with abnormal foot motion during running, custom-made orthotic shoe-inserts may help reduce symptoms.

Although rare, a person with chronic ECS will sometimes develop a more severe "acute" compartment syndrome; one in which the symptoms do not resolve. Acute compartment syndromes are usually seen as a result of trauma, such as a crush injury or a motor vehicle accident. There have been recent reports suggesting a connection between acute compartment syndromes and the use of the supplement creatine. If severe pain or numbness persists for more than 2 hours after exercise, emergency care should be sought. This condition is considered a surgical emergency.

The diagnosis of CECS is becoming more common because of heightened awareness. There are currently several ongoing research inquiries to more rapidly and accurately diagnose CECS. Coaches, parents and runners should inquire about the diagnosis from a sports medicine physician if they or their athletes have experienced long standing leg pain, exertional numbness, or long-standing "shin splints" which do not improve. Although debilitating, CECS is usually "cured" uneventfully with surgery allowing a relatively rapid and symptom-free return to running.