|Wednesday, March 1
Every morning before work, you go on a five-mile run. But for the last month you've been experiencing pain in your shin just as you reach the four-mile mark. It develops suddenly, starting as a dull throb and quickly becoming excruciating. Then it disappears as fast as it came on, within minutes after you've stopped running. Furthermore, it doesn't happen when you're biking or swimming. It's possible you may have shin splints, but most probably you're suffering from compartment syndrome -- an affliction that can strike recreational as well as elite athletes.
"The pain comes on fairly predictably after a certain time or distance, for instance when running," says Dr. Jan Fronek, a member of the Association of Professional Team Physicians (PTP) and head team physician for the San Diego Padres. "Yet on physical exam while the patient is resting, the exam or symptoms may be pretty unremarkable."
Join Dr. Fronek as he talks about the particulars of this condition -- what it is, how it's caused and why it can be difficult to diagnose.
What is compartment syndrome?
Dr. Fronek: There is a layer of tissue called fascia that surrounds the muscle and acts like an envelope that allows the muscle to perform efficiently. With exercise, the muscle will enlarge, and sometimes that envelope is too tight for a particular muscle group. If it is, then the pressure inside the muscle compartment can increase and cause damage to the tissues, specifically to the nerve and muscle cells. The increase of the pressure to the nerves can result in pain in the extremity, numbness and tingling and, at worst, paralysis. The muscle can become weak and function poorly and can ultimately die.
What causes the increase in pressure?
Dr. Fronek: In the acute setting, the increased pressure can result from direct trauma, a direct crush injury to the muscle or a fracture where there is a lot of bleeding into that muscle compartment. On the other hand, it can develop over a long period of time -- a condition called recurrent or chronic compartment syndrome -- which results from some type of exertional activity such as running, playing tennis, etc. This is most often observed in the lower extremities. In muscle training or weight lifting, the muscle size can increase (muscle hypertrophy), and the fascia doesn't always accommodate this increase, leading to an increase in the pressure of the muscle compartment.
Is compartment syndrome related to shin splints?
Dr. Fronek: The diagnosis of shin splints is very inaccurate. It simply describes that the patient has leg pain. It is important to make a more precise diagnosis: The patient with an injury to the bone may have a stress fracture; injury to the tendon may result in tendinitis; or a variety of other problems including a compartment syndrome may be relevant to consider.
I think it's accurate to describe shin splints as a type of start-up, beginning-of-training leg pain that should resolve in about two weeks once the person starts to work his way into shape. If the pain does not go away, then I think one needs to re-evaluate the diagnosis. Generally in patients with recurrent compartment syndrome the pain is localized to the muscle, it is exertional and fairly reproducible.
What are the symptoms?
Dr. Fronek: Most patients will have exertional leg pain (pain while the muscle is being used). The pain is most often centered on the anterior or front part of the lower leg, the big muscle group that is prominent along the front of the shin. Moreover, it comes on fairly predictably after a certain time or distance -- for instance, when running. A person may get some numbness and tingling in the foot as the nerves are compromised and he actually may feel swelling. The muscle compartment may get hard and painful to the touch.
On physical exam while the patient is resting, the exam or symptoms may be pretty unremarkable. The only hint that a physician may see is that approximately 50 percent of patients will have fascial hernias, or small defects (size of a nickel or quarter) in the fascia that become prominent when a person squats down. There are normally a few openings around the fascia that allow the nerves to exit out from the muscle compartment to the skin. The thought is that if the pressure progressively stretches the fascia, the small defects can enlarge and create a greater opening.
In the past people have tried to repair these defects, and that is not advisable. This will simply increase the pressure in the muscle compartment and at best will not make things any better and unfortunately can make matters significantly worse.
How is compartment syndrome diagnosed?
Dr. Fronek: The most helpful thing in diagnosing the syndrome is the history (description of the problem by the patient) and the presence of fascial defects upon physical exam. I think it's important to take an X-ray alone or in combination with a bone scan to look for other injuries like stress fractures.
But to confirm the diagnosis of compartment syndrome, it's essential to measure the pressure in the muscle compartment. It's an invasive study that places a tiny catheter inside the muscle compartment and measures pressure before, during and after exercise. There are criteria as to what is abnormal pressure and that's the one way of confirming the diagnosis. This also determines which compartments are affected because occasionally the posterior compartment can be involved.
There is interest in terms of making this diagnosis in a non-invasive fashion such as through MRI or specific scanning techniques. These are probably not as accurate for diagnostic purposes but are appealing because they are non-invasive.
How is the condition treated?
Dr. Fronek: Most of the time non-surgical treatments are not effective if the person wants to continue with his type of exercise. The runners or tennis players we see who have the symptoms generally continue to have them if they pursue that chosen activity. Generally, surgical treatment, which is a release of the muscle compartment so that there is more room for the muscle to function in, is the treatment of choice and provides good results.