Running Injury – Compartment Syndrome

Compartment Syndrome in the legs is a problem that many runners suffer from. It is caused by muscle swelling or increased osmotic pressure in the muscles, and can result in pain, swelling, and motor loss or weakness. The swelling is induced by activity, especially the muscle activity associated with running.

Each leg contains four osseofacial compartments which are surrounded by fairly inelastic facial covering. This means that each group of muscles is surrounded by a thin, inelastic sheath. Within each compartment, there is a major nerve. When the muscles swell beyond the elasticity of the sheath surrounding them, the pressure is felt on the major nerves in the area. As exercise continues in duration, the muscle continues to swell up to its maximum volume. However since the sheath can not expand, the pressure within the compartment continues to increase. The pain can become unbearable and exercise must cease in some cases. In other cases the nerves are pinched to the extent that the feet and lower legs go numb and become basically inoperative.

Knowing that you have compartment syndrome can be a tricky process. Often pain associated with the shins and calves is misdiagnosed as a stress fracture. A bone scan is a good idea to rule out any problems with the bones. An MRI may help to diagnose the problem, but is often not conclusive. The key to recognizing compartment syndrome is motor loss, as it is the most unique characteristic. The final way to diagnose the problem is to measure the intercompartmental pressure, done with a needle which is slid into the compartment, and a hand held pressure measurement device.