An unusual variant of popliteal artery entrapment

A 43-year-old woman presented with incapacitating exertional pain in the right foot, ankle, and lower calf of 1 years' duration following a minor ankle sprain. Evaluation by several physicians had been inconclusive. Physical examination identified normal pedal pulses at rest but obliteration of pulses with active plantar flexion. Segmental pressures were normal at rest and duplex scanning showed occlusion of the popliteal artery with active plantar flexion. The findings were confirmed by arteriography despite a normal course of the popliteal artery. Magnetic resonance imaging (MRI) showed no muscular abnormality. At exploration entrapment was noted to be the result of compression by branches of the sural nerve and vein as they coursed medially inserting into the medial head of the gastrocnemius muscle. Division of the neurovascular bundle resulted in complete resolution of symptoms and arterial compression on duplex examination postoperatively. This case was unusual because of the patient's age, sex, and the pathologic findings that had not been previously reported. In this case MRI was not useful in demonstrating a muscular or neurovascular bundle abnormality, supporting the use of duplex scanning as the noninvasive diagnostic modality of choice.