FUNCTIONAL POPLITEAL ARTERY ENTRAPMENT SYNDROME: INVESTIGATION WITH DYNAMIC AND DOPPLER ULTRASOUND

A. Background Functional popliteal artery entrapment syndrome (fPAES), a cause of exertional leg pain, has a clinical presentation and clinical findings that are often indistinguishable from those of other leg pain causes (1). This condition may also coexist and overlap in symptomatology with other leg pain causes, further complicating the diagnosis (2). Although fPAES is usually considered a rare cause of leg pain (3), the true incidence of this condition is unknown, and fPAES is likely underdiagnosed and underreported (4). A missed diagnosis may result in disease progression and the use of unnecessary invasive procedures (3), and untreated fPAES may lead to popliteal artery damage, embolization, and limb ischemia (5). Although a diagnostic method using a combination of dynamic ultrasound and MR imaging/MR angiography has been described for fPAES (5), to our knowledge, no investigational studies have been performed to assess the dynamic ultrasound findings in this entity. This study sought to evaluate the usefulness of dynamic plantar flexion and dorsiflexion of the calf and the effect on the popliteal artery Doppler waveform in patients with clinically suspected fPAES and no structural abnormality. B. Methods We performed a retrospective review of ultrasound studies in patients who presented with clinically suspected PAES over a 3-year period. The ultrasound studies consisted of an anatomic survey of the popliteal. Dynamic nonresistant dorsiflexion and plantar flexion evaluations of the popliteal artery plus spectral Doppler evaluations of the popliteal artery obtained in neutral, plantar flexion, and dorsiflexion positions were performed before and after patients exercised. Patients with anatomic abnormalities were excluded. The following parameters were assessed: The proportion of symptomatic knees versus asymptomatic knees in which plantar flexion and/or dorsiflexion of the foot resulted in popliteal artery compression. The peak systolic velocity (PSV) of the popliteal artery in all positions for knees with and knees without dynamic popliteal artery compression. The absolute value change in PSV of the popliteal artery from neutral to plantar flexion and from neutral to dorsiflexion in the pre- and postexercise state for knees with and knees without dynamic popliteal artery compression. ROC analysis for clustered data was used to assess the ability of PSV to distinguish between knees with and knees without arterial compression. C. Results A total of 88 knees (77 symptomatic, 11 asymptomatic) in 45 patients were included in the study. Dynamic arterial compression was observed in 38% (29/77) of symptomatic knees. No compression seen in asymptomatic knees. Both pre-exercise and postexercise knees with arterial compression had significantly higher absolute changes in PSV from neutral to plantar flexion versus knees without arterial compression (Table). There was a smaller significant change in PSV from neutral to dorsiflexion in the pre-exercise state. There was no significant change in PSV in the postexercise state from neutral to dorsiflexion or with respect to PSV values at any position between knees with and knees without arterial compression. D. Conclusions/Significance In patients with clinically suspected PAES without anatomic abnormality, dynamic ultrasound demonstrated compression of the popliteal artery in 38% of knees. No dynamic arterial compression was seen in asymptomatic knees. There was a significant elevation in PSV from neutral to plantar flexion in pre- and postexercise states and from pre-exercise neutral to dorsiflexion positions in knees with arterial compression versus knees without arterial compression. Tables [Table: see text] References Joy SM, Raudales R. Popliteal artery entrapment syndrome. Curr Sports Med Rep. 2015;14(5):364-367. Hislop M, Kennedy D, Cramp B, Dhupelia S. Functional popliteal artery entrapment syndrome: poorly understood and frequently missed? A review of clinical features, appropriate investigations, and treatment options. J Sports Med (Hindawi Publ Corp). 2014;2014:105953. Gaunder C, McKinney B, Rivera J. Popliteal artery entrapment or chronic exertional compartment syndrome? Case Rep Med. 2017;2017:6981047 Hislop M, Brideaux A, Dhupelia S. Functional popliteal artery entrapment syndrome: use of ultrasound guided Botox injection as a non-surgical treatment option. Skeletal Radiol. 2017;46(9):1241-1248. Williams C, Kennedy D, Bastian-Jordan M, Hislop M, Cramp B, Dhupelia S. A new diagnostic approach to popliteal artery entrapment syndrome. J Med Radiat Sci. 2015;62(3):226-229.