Tibia fractures, among others, might be complicated by a so-called compartment syndrome. What is compartment syndrome and how is it diagnosed, and treated?
Compartment syndrome is the clinical condition of increased pressure within an enclosed fascial space, potentially leading to ischemic damage of muscles and nerves.
The leg is a typical location affected by compartment syndrome because of its well-defined compartments: anterior, medial, superficial posterior, and deep posterior (Figure 1). These compartments are surrounded by thick fascia, which does not allow for significant volume expansion without dangerous increases in pressure.
Figure 1: The four compartments of the leg and their contents are shown in a cross-section (modified from Wikipedia). The anterior compartment is shown in red, lateral in blue, deep posterior in green and superficial posterior in purple.
Compartment syndrome most often occurs secondary to bleeding and extravasation of fluid, which can occur after bone and soft tissue damage (ex. tibial fracture). Other causes are compressive devices (casts and ACE wraps), IV infiltration (fluid infused directly into the compartment), and burns (tissue restriction). Some patients can also develop compartment syndrome after vascular repair secondary to reperfusion injury.
Signs and Symptoms
The hallmark of compartment syndrome is “pain out of proportion to exam,” or pain that is more severe than expected given the injury/situation. An example of this is a patient with a splinted fracture who experiences increasing pain over time. Even though one cannot know how much pain another person experiences, because one would expect a decrease in pain once the injury is immobilized, a report of more pain after splinting would be alarming (and “out of proportion” to what’s expected).
If a patient is using a patient-controlled analgesia machine (one from which pain medicine is self-administered, by pushing a button), tracking the frequency at which patients request medication can give a quasi-objective measurement of the intensity of pain over time.
In advanced cases of compartment syndrome, a patient might develop what is known as the 6 P’s: pain, paresthesia (numbness), paresis (weakness of the affected area), pallor (pale skin), pulselessness (absent distal pulses), and poikilothermia (cold skin).
Diagnosis & Treatment
A key step in recognizing compartment syndrome is the physical exam. Examination might reveal swollen and shiny skin, and squeezing of the compartment will elicit exquisite pain. Examination might also reveal very little, especially in context of the injury; that is, a patient with a broken tibia and a compartment syndrome might present pretty similar to a patient with a broken tibia and no compartment syndrome.
To confirm the diagnosis of compartment syndrome, one can directly measure the pressure of the compartment by inserting a needle attached to a pressure meter.
Treatment is fasciotomy, a procedure where long surgical cuts are made in the fascia to relieve the pressure. The incisions are generally left open for 48-72 hours until they are closed in a second surgery.
If left untreated, the compartment’s pressure will prevent blood flow leading to damage of the muscle and nervous tissue. This can result in permanent nerve damage, loss of muscle function, and even result in amputation.
Additional Points to Consider
The interested reader is referred to the chapter on compartment syndrome for additional details