Flexor hallucis longus muscle atrophy due to a chronic compartment syndrome of the lower leg.

The leg has four compartments anterior, lateral, superficial and deep posterior which are prone to produce ischaemic damage to muscle and nerves when intractable swelling is present. The clinical picture of the acute compartment syndrome comprises symptoms such of pain, pallor, paresthesia, pulselessness and finally, paralysis. The syndrome in its chronic form is seen in long distance runners and other endurance athletes and it differs from the acute compartment syndrome in having only some of the classical features. The pathology in chronic compartment syndrome is due to non-yielding compartmental boundary formed by an excessively tight fascia causing abnormally high tissue pressure at rest. The pressure is further increased by muscle activity to a point that interferes with muscle blood flow during intensive activity and the metabolic demands of the tissues are no longer met (Martens et al, 1984).