Answer:
Compartment syndrome is an elevation of interstitial pressure in a closed fascial compartment that results in microvascular compromise; as the duration and magnitude of interstitial pressure increase, muscle and nerve function are impaired and necrosis of soft tissues eventually develops. Signs include: extreme pain out of proportion to the injury; pain on passive extension of the toes (flexed posture); pallor; paralysis; paresthesias (early loss of vibratory sensation); and pulselessness.
Various methods have been used to measure the intercompartmental pressure, including slit catheters and saline injection techniques. Portable commercially produced units are available, however, an 18-gauge needle flushed with saline and connected to a transducer is usually adequate. Blick et al. considered a pressure >30 mm Hg in any compartment an indication for fasciotomy. Allen et al. considered fasciotomy when the compartment pressure was >40 mm Hg for six hours or was >50 mm Hg for any length of time. Four-compartment fasciotomy should be performed even with any index of suspicion of compartment syndrome, as the morbidity of a fasciotomy is far less than the morbidity of ischemic necrosis of the lower extremity secondary to compartment syndrome.
Decompression is done by fasciotomies of the anterior, lateral, superficial, and deep posterior compartments of the leg. A longitudinal incision is made halfway down the leg 2 cm anterior to the fibula overlying the anterior intermuscular septum. Through this incision, the anterior and lateral compartments are released, taking care to avoid injury to the superficial peroneal nerve. An additional incision is made posteromedially 2cm posterior to the edge of the tibia. The saphenous vein and nerve are retracted and the fascia overlying the superficial posterior compartment is released. The soleus is retracted to expose the fascia covering the flexor digitorum longus muscle just posterior to the tibia. This fascia is longitudinally incised releasing the deep posterior compartment.
Compartment syndrome of the thigh can occur but is uncommon because of the large volume that the thigh requires to cause a pathologic increase in interstitial pressure. Fascial compartments blend anatomically with the muscles of the hip, potentially allowing extravasation of blood outside the compartment.