Compartment Syndrome of the Lower Leg (Acute)
Edited by Mark Perry MD
Compartment syndrome of the lower leg is a very painful and potentially devastating condition. It is often associated with trauma, such as a shin bone (tibia) fracture or crush injury. Any condition that causes excessive swelling of the muscles in the lower leg can cause compartment syndrome. The swollen muscles are confined by the thick and fibrous tissue (fascia) that runs around the lower leg.
There are four compartments in the lower leg – one in the front (anterior), one on the side (lateral), and two on the back (posterior). If the muscle tissue swells excessively, it can reach the point where blood cannot deliver oxygen to the muscles or nerves. This creates intense pain and may lead to muscle death after approximately six hours. If this occurs, these muscles will not recover. Treatment of an acute compartment syndrome is an urgent surgical release of the constricting fascia (fasciotomy) allowing blood flow and oxygenation to the muscle and nerves.
A typical scenario for the development of a lower leg compartment syndrome is a patient who suffered a high-energy trauma (car accident, gun shot, fall from a ladder). If there is excessive swelling the patient may develop intense pain in the leg after the injury or even after fixation of the broken bone. In the hospital setting, patients with compartment syndrome usually demonstrate increased demand for pain medication to overcome the intense pain.
In patients with multiple injuries, including head trauma, tests involving direct pressure measurement with needles may be necessary. Serial examination, close observation, and clinical suspicion are essential to early diagnosis. External or exercise-induced compartment syndrome of the lower leg may also occur as a result of intense chronic repetitive use. For example, an individual who runs a marathon with inadequate training may cause such muscle damage and swelling that a compartment syndrome develops.
Physical examination can be subtle, although the classic signs are quite striking. The main sign is intense pain in the lower leg when an examiner moves the muscles within that compartment. For example, moving the ankle or the toes results in excruciating pain. Numbness in the foot and even loss of pulses may develop. Examination of the leg will show that instead of being soft and “push-ale” the involved muscular compartment becomes “rock hard” when pressed.
Imaging and Investigations
There are no specific imaging studies that will diagnose compartment syndrome, although x-rays may show a fracture that could possibly result in causing a compartment syndrome.The main diagnostic criterion is a good clinical exam. Pressure monitoring of the compartments with a pressure-sensitive needle can confirm the diagnosis. There are several ways to interpret the pressure “number” either by the absolute value or its relation to the blood pressure.
If compartment syndrome is diagnosed or is clinically suspected, the treatment is surgical release fascia of the leg. The muscles will then bulge out. Muscle that does not appear to be healthy is removed. After releasing the tight fascia the muscles and nerves begin to receive adequate oxygenated blood to keep the tissue alive.
This type of surgery is done on an urgent basis. Often after surgery, it may not be possible to close the incisions because of the excessive swelling. Sterile dressings can be applied to the wounds and the patient can return to the operating room later for removal of more muscle, delayed wound closure, or a skin graft.
Sequela of compartment syndrome
If a compartment syndrome occurs and there is muscle death, the tissues in this area will be permanently damaged. In the lower leg, fixed foot or ankle positions may need surgery to place the foot in a “more usable” alignment. The foot may not be able to bend up or bent “down and in” depending on the involved compartments. Damage to nerves may result in pain or increased sensitivity.
To avoid later problems, an acute compartment syndrome of the lower leg is a true orthopedic emergency.
Edited December 19, 2016
Previously edited by Hossein Pakzad MD