Necessity of Early Recognition of Popliteal Entrapment Syndrome

CASE REPORT
doi: 10.14721/pscience.2015.e29
Necessity of Early Recognition of Popliteal Entrapment Syndrome
Marlin Wayne Causey, Niten Singh, Seth Miller, Charles Andersen
Department of Vascular Surgery, Madigan Army Medical Center | Tacoma, Washington, USA.
ABSTRACT
Popliteal Entrapment Syndrome (PES) is a rare cause of
claudication in the young population. Diagnosis is often
difficult, especially if providers are not familiar with the disease
and the diagnosis. Delays in diagnosis of PES are frequent and
unfortunately are associated with significant limb threatening
complications. Early diagnosis is key to successful treatment
of PES and allows for optimal surgical treatment- resection of
the compressive muscle, most frequently the medial head of the
gastrocnemius muscle, instead of bypass when irreversible arterial
trauma has occurred. This paper describes the history of PES as
well as examples of the wide spectrum of clinical presentations of
PES and discusses the diagnosis, appropriate workup, options for
surgical treatment based on findings, and the latest advances in
ensuring adequate resection and optimal recovery.
Citation: Causey MW, Singh N, Miller S, Andersen C (2015) Prog Science
2(4):e29 | doi: 10.14721/pscience.2015.e29
Original Published: J Surg Radiol. 2011 April 1;2(2) | Republished: 04/08/2015
Copyright: © 2015 Causey MW. et al. Published by TranScience. This is an open
access article distributed under the terms of the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any
medium, provided the original author(s) and source are credited.
Funding: none
Competing Interests: The authors have declared that no competing interests exist.
E-mail: [email protected]
Figure 1 | Abnormal accessory muscle slip and compression of the
popliteal artery. Resection of the accessory muscle slip relieved the
compression of the popliteal artery.
CASE 1
The first case is a 43 year old active male with an 8 month history of
left calf pain. He presented secondary to an acute episode of pain that
occurred while running on a treadmill that caused him to immediately
stop. Over the next 8 months, his calf pain continued to worsen with
activity and he was evaluated by numerous specialties, primary care,
neurology, and orthopedics, including several radiologic studies and
even an EMG. After a lengthy diagnostic process, he was referred
to a vascular surgeon for evaluation. His history was significant for
classic symptoms of claudication, worse when walking uphill, and
had progressed so that he was unable to walk a quarter mile. Physical
examination revealed palpable pulses in his right foot that decreased
when standing on his toes and strongly palpable pulses on the left foot
through all ranges of motion. Duplex ultrasonography demonstrated
a patent right popliteal artery that occluded with plantar flexion and
an ankle brachial index (ABI) of 1.08 that decreased to 0.6 after
exercise in the right foot. He underwent myectomy of the medial
head of the gastrocnemius and an accessory muscle slip (Figure 1)
and postoperatively the patient recovered and returned to his previous
functional status.
INTRODUCTION
Popliteal entrapment may become a limb threatening disease if
not recognized in a timely fashion. Many people have the anatomic
abnormality of popliteal entrapment, but when combined with
clinical symptoms becomes popliteal entrapment syndrome (PES).
The treatment of PES is surgical through decompression in the
early stages and bypass in advanced stages of the disease. Essential
to the optimal treatment is early diagnosis as an increased interval
between symptoms and diagnosis increases the risk of complications
from PES and potential limb loss. Early diagnosis also decreases the
necessity for lengthy surgery. In this report, several cases of popliteal
entrapment syndrome are presented demonstrating the necessity of
early diagnosis and that a delay in diagnosis may lead to an autologous
saphenous vein bypass due to limb threatening complications. All of
the cases, the patients had seen multiple physicians prior to being
evaluated by a vascular surgeon and represent very typical cases
demonstrating the workup and management of PES.
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Case Report | Popliteal Entrapment Syndrome
Figure 3 | A. CT scan demonstrated normal anatomy of the femoral
and popliteal arteries bilaterally on 3D reconstruction (left) and coronal
imaging (right). B. Angiography at rest demonstrated normal anatomy
of the popliteal artery without occlusion (left). With active plantar
flexion of the left foot, compression of the popliteal artery is noted with
stenosis on angiography (subsequent sequential images). C. Popliteal
artery exposure through a posterior approach and mobilization of
the medial head of the gastrocnemius muscle. D. After mobilization
of the medial head of the gastrocnemius muscle, curative treatment
involves resection of the medial head of the gastrocnemius muscle.
E. Intraoperative duplex ensures that the resection is appropriate and
effective use is outlined. Top left- intraoperative duplex is obtained
at rest to obtain a baseline and determine peak systolic velocities and
wave forms. Top right- passive dorsiflexion (patient under general
anesthesia) demonstrates compression as there are decreased systolic
velocities as dorsiflexion increases. Bottom left- after initial resection of
visibly obvious muscular compression, ultrasound allows confirmation
of appropriateness of resection, in this case resection was not complete
and further muscle was resected. Bottom right- after additional
resection, the foot is maximally dorsiflexed and there is no change in the
arterial wave forms or the peak systolic velocities. F. Original resected
specimen (right) and additional resection (left) after use of intraoperative
ultrasound ensured no further compression of the popliteal artery.
Figure 2 | A. Ultrasound demonstrating occlusion of the right
popliteal artery at rest with flow through the left popliteal artery. B.
Axial CT scan demonstrates occlusion of the right popliteal artery
and preserved flow through the left. C. 3D CT reconstruction with
occlusion of the right popliteal artery and this correlates well with
angiography demonstrating large sural collateral branches. D.
Surgical treatment of the popliteal occlusion; top left demonstrates
identification of the popliteal artery through a posterior S-shaped
incision. Top right demonstrates the medial head of the gastrocnemius
muscle and the compression of the popliteal artery. Middle shows
the mobilization of the medial head of the gastrocnemius muscle as
is required for full decompression. Bottom left demonstrates that
after resection of the medial head of the gastrocnemius muscle that
there are arterial changes at the area of occlusion (stenosis) with post
stenotic dilatation. This represents significant repetitive trauma to the
popliteal artery. Given these changes, interposition bypass graft using
greater saphenous vein was required and successful for treatment
(bottom right).
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Case Report | Popliteal Entrapment Syndrome
Figure 4 | In order to prevent these complications of a delayed diagnosis, the following approach is advocated for diagnosis, treatment, and
to ensure adequate resection for popliteal entrapment syndrome.
CASE 2
climber and inclined treadmill. An astute physician noted that she had
a normal pulse exam and that this was diminished when she plantar
flexed her foot. ABI at rest was 1.14 on the right and 1.37 on the left
with positional ultrasound demonstrating decreased flow through the
popliteal artery. A CT scan demonstrated normal anatomic location
of her popliteal arteries and angiography demonstrated stenosis
with active plantar flexion (Figure 3). She underwent resection of
the medial head of her gastrocnemius muscle using intraoperative
ultrasound that demonstrated a need for additional resection and
completion ultrasound ensured adequate and appropriate resection.
Postoperatively she recovered quickly and returned to her previous
highly athletic activities.
The second case is of a 25 year old performance athlete with a
history of right lower leg and foot pain with exertion who presented
acutely with numbness and cyanosis of the affected extremity. Over
the previous several months he had been evaluated by primary
care providers with no definitive diagnosis. Upon presentation, he
had numbness and cyanosis of his right lower leg with no Doppler
signals in his feet. Upon initial evaluation in the Vascular Surgery
clinic, he was noted to have absent pedal pulses. He underwent
immediate ultrasound, CT scanning, and arteriogram which revealed
a laterally displaced and occluded right popliteal artery (Figure
2). Intraoperatively he was noted to have stenosis, post stenotic
dilatation and run off angiogram demonstrated distal embolization.
He underwent saphenous vein bypass from the traditional posterior
approach and recovered uneventfully.
DISCUSSION
The anatomical abnormality seen in PES was first noted by a medical
student, T.P. Anderson Stuart, in 1879.1 Subsequently in 1965, Love
and Whalen coined the term and suggested a classification (types
I-IV).2 In 1967, Norman Rich expanded the classification to include
entrapment of both the artery and the vein (type V).3 More recently a
functional entrapment has been noted that is only reproducible during
CASE 3
A 39 year old active female presented to her primary care physician
with complaints of foot and calf pain when she exercised on a stair
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Case Report | Popliteal Entrapment Syndrome
examination and imaging studies with provocative maneuvers (type
VI). The incidence of popliteal entrapment (anatomical abnormality)
has been noted at 3.5% in a study conducted in 1977 on 86 cadaveric
specimens4 and more recently at 0.47% in a Greek study of 20,000 in
processing military recruits- 90% males and 34% bilateral.5 However,
only when the anatomical abnormality is combined with clinical
symptoms do patients have PES.
The classification of popliteal entrapment is based upon the
embryologic development of the popliteal artery. Normally the
popliteal artery forms after the migration of the medial head of the
gastrocnemius muscle. If the artery forms prematurely, the medial
migration of the gastrocnemius will displace the artery medially.
When the gastrocnemius normally inserts Type I entrapment occurs,
but when there is an abnormal insertion of the gastrocnemius muscle
onto the femur a Type II entrapment occurs. When mesodermal
remnants of the popliteal artery are left within the popliteal fossa, an
abnormal slip of muscle or fibrous band occurs and may compress
the popliteal artery and this is classified as Type III. Type IV occurs
when the embryologic blood supply persists deep to the popliteus
muscle and results in popliteal artery compression.6 Most recently
Type VI or functional entrapment has been noted to occur when there
is compression of the popliteal artery by normal or hypertrophied
gastrocnemius muscle or compression as the popliteal artery passes
through the soleal sling, with compression occurring with activity but
an absence of anatomic abnormalities at the time of surgery.7,8
The pathophysiology of vessel compromise occurs due to repetitive
trauma by the compressing muscle leading to inflammation and
fibrosis of the popliteal arterial wall.6 With each muscle contraction
the artery is stressed and gradually the repetitive compression and
arterial damage leading to stenosis, poststenotic dilatation, and
ultimately occlusion of the popliteal artery. A delay in diagnosis
leads to continued trauma leading to irreversible arterial changes.
Essential in reversing this process is prompt diagnosis and surgical
resection of the offending anatomic abnormality, as defined by the
entrapment type.
The history presented by most patients with popliteal entrapment is
of exertional pain relieved by rest that is reproducible and consistent.
The patients will also describe pain that is worsened, claudication,
when walking or running uphill secondary to prolonged contraction
of the gastrocnemius musculature on the artery. Physical exam
is important as pulse exam at rest is typically normal and only
diminishes with plantar flexion of the foot. Once the diagnosis of
PES is entertained, further workup begins with an exercise ankle
brachial index (ABI), which consists of an ABI at rest and then
repeating of the ABI after a graded exercise treadmill test. Duplex
ultrasonography of the popliteal artery with plantar flexion of the
foot also helps to confirm the diagnosis of popliteal entrapment. In
order to determine the type of popliteal entrapment, a CT angiogram
will identify abnormal muscular abnormalities in the popliteal fossa
(types I, II, IV, and V) and angiography will identify functional
compression as the angiogram is performed at rest and with plantar
flexion (Figure 4). Surgery, the only treatment, most commonly is
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performed with a posterior S-shaped incision over the popliteal fossa
or less commonly through a medial incision. The tibial nerve is
mobilized and protected and the popliteal artery and vein identified
and any anatomical abnormality corrected through resection. When
poststenotic dilatation, thrombosis, or embolization are encountered,
surgical treatment involves interposition saphenous vein bypass of
the diseased segment. Recently described is the use of intraoperative
duplex, performed after resection, and after resection to ensure no
further compression of the popliteal artery and to evaluate extent
of arterial wall changes.9 Proper use of intraoperative ultrasound
involves moving the foot through all ranges of motion, particularly
dorsiflexion, as the patient is under general anesthesia and dorsiflexion
is the passive corollary to active plantar flexion (Figure 3). The patient
is allowed to ambulate on postoperative day 1 and typically returns to
their prior active status within 6 weeks.
CONCLUSION
By recognizing that claudication in the young athletic population
is rare and a potential cause is PES, early diagnosis is possible.
Studies have demonstrated that up to 3% of the population may have
entrapment and early diagnosis will prevent the complications of
delayed diagnosis such as stenosis, post stenotic dilatation, thrombosis,
premature atheroma formation, aneurysm, and embolization. By
recognizing the disease early and getting appropriate imaging
studies with appropriate provocative maneuvers – exercise ABIs,
duplex ultrasound, CT angiography, MR angiography, or angiogramcomplications may be avoided. Additionally, early diagnosis allows
for easy surgical decompression and a delay in diagnosis leads to
more complex and risky surgical treatment when irreversible arterial
changes have occurred necessitating a bypass of the diseased segment.
DISCLOSURES
The authors have no disclosures or conflicts of interest related to
this manuscript.
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