Chapter 39

### PATIENT STORY

A 28-year-old male athlete presented with increasing difficulty running, resulting in severe bilateral calf cramping. He consulted with orthopedics and neurosurgery with no definite etiology identified. Vascular surgery was consulted with a provisional diagnosis of a compartment syndrome. On physical examination he had normal pulses at rest. Diminution of dorsalis pedis and posterior tibial pulses was appreciated on both plantar flexion and dorsiflexion. Duplex ultrasound examination showed normal signals at rest, obliteration of arterial signals on plantar flexion, and reactive hyperemia on a neutral foot position.

### PATHOPHYSIOLOGY

Popliteal entrapment syndrome consists of a group of conditions where vascular and/or neurologic compression symptoms result due to compression of the popliteal artery, vein, or nerve. The compression is due to a congenital anomaly where the popliteal artery becomes functionally occluded by passing medial to and under the medial head of the gastrocnemius muscle or a slip of that muscle, with consequent compression of the artery.

• Relationship of muscle and artery in the popliteal fossa resulting in extrinsic arterial compression.

• Repetitive insult to the popliteal artery can cause arterial damage and lead to aneurysm, thromboembolism, and arterial thrombosis.

Although there are several classifications, the four types of embryologic entrapment in a commonly used classification system are shown in Figure 39-1.1,2

###### FIGURE 39-1

Types of popliteal artery entrapment. Type 1 shows location of the medial head of gastrocnemius muscle, which is attached more laterally than is normal, with resulting popliteal artery entrapment. Type 2 shows an abnormal course of the popliteal artery, with entrapment. Type 3 shows location of an anomalous muscle band with abnormal attachment, with resulting popliteal artery entrapment. Type 4 shows primitive position of the distal popliteal artery posterior to the popliteus muscle. (Reprinted from Pillai J. A current interpretation of popliteal vascular entrapment. J Vasc Surg, 2008;48:S61-S65, with permission from Elsevier.)

### CLINICAL FEATURES

• The mean age of patients is 32 years.3

• Patients are more commonly male.

• About one-third of patients have bilateral entrapment.4

• History of leg pain or aching and tiredness; cramping on walking or exercise (intermittent claudication), which is relieved by rest, is the most common presenting symptom. Some swelling may also be described.

• A number of patients may remain completely asymptomatic until the artery is either severely narrowed or completely thrombosed.

• Occasionally patients may present with acute arterial ischemia due to thrombosis of the popliteal artery from long-standing entrapment, intimal damage, and eventual thrombosis. The tip-off is the young age of the patient, no evidence of arteriosclerosis elsewhere, and the prior history of claudication as described above.

• Examination can show arterial compression elicited by maneuvers such as plantar flexion and dorsiflexion of the feet.

### DIAGNOSIS

• The diagnosis is made ...

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