Popliteal Artery Entrapment Syndrome (PAES)
Popliteal Artery Entrapment Syndrome (PAES) is an obscure cause of exercise induced calf pain.
Posterior calf pain is a common presentation in the young athletic population, and so it is important
to recognize that PAES is an uncommon presentation. Therefore, it is important to consult your
regular Physio if you are experiencing ongoing pain, they can perform a thorough assessment to
correctly diagnose your issue. However, our interest today lies in PAES and how its presentation is
very similar to chronic exertional compartment syndrome (compartment syndrome), commonly
referred to as shin splints or calf cramps. This article looks to detail the specific differences between
the two conditions and explore potential treatment options that can be explored.
PAES typically affects a young 20-40yo athletic population and is up to 15x more common in males
than females. PAES is where the popliteal artery becomes dynamically compressed by the medial
gastrocnemius (gastroc) head through exercise. Causes are either anatomical variance in the medial
gastroc insertion or excessive hypertrophy of the muscle. The popliteal artery dilates as the blood
pressure increases in the vessel causing a dynamic compression against the medial gastroc head.
Patients with PAES will typically present with intermittent claudication (posterior calf pain/cramping)
and/or paraesthesia during exercise or exertion. This presentation is almost identical to the typical
compartment syndrome where the calf muscles swell from increased blood perfusion and become
compressed against the fascia. The main subjective difference is that PAES is more specifically
exacerbated by exercise intensity rather than volume. Whereas compartment syndrome requires a
certain duration of exercise to present, PAES can present almost instantly under the right
circumstances i.e running uphill, repetitive jumping, sprinting. Another difference is that athletes
with compartment syndrome will have decreased tolerance to exacerbating factors as a game
progresses whereas PAES symptoms remain consistent relative to intensity.
Differentiation between the two conditions can be determined therefore with a few clinical tests
and confirmed on imaging. Exercises such as repeated hopping on one leg or running can be used to
induce symptoms in the clinic. PAES will present sooner than compartment syndrome with a loss of
the dorsalis pedis or posterior tibial pulse, symptoms also settle a lot quicker as they settle with the
recovery of the athlete’s heart rate and blood pressure. If PAES is suspected, diagnosis can be
confirmed with a dynamic MRAngiogram, where the patient performs their provocative activity and
then the scan is performed. A positive test will show decreased blood flow through the popliteal
artery as it intersects the proximal medial gastroc head.
Early detection and intervention is important as prolonged stenosis of the vessel can cause scarring
and atherosclerosis of the inner vessel wall. If left untreated PAES may require invasive procedures
to stent the vessel open and can significantly impact an athlete’s career. Therefore, early detection is
key. Standard treatment of PAES involves relocating the medial gastroc head, optimizing the
popliteal artery tract. However, botulinum A toxin (botox) injections used locally to the site of
constriction in the medial gastroc head has gained traction in recent literature and is showing
promising results. The procedure is far less invasive than traditional measures and has been shown
to effectively reduce the muscles constriction of the vessel during exercise. Another benefit is that
recovery time is significantly reduced, the player can return to sports almost immediately as function
and pain allow.
Physio management is involved in retraining the muscle to promote muscle atrophy in the medial
gastroc head and guide successful return to sport. Long term management involves educating the
patient to avoid excessive training of calves that would promote increased medial calf bulk which
would encourage the condition to return.
Take home, is that this condition is quite RARE. Your exercise induced calf pain is far more likely to
be a result of the more common diagnoses, such as compartment syndrome. However, the purpose
of this piece is to explore this interesting albeit rare condition and raise awareness of potential
differential diagnoses that exist with exercise induced calf pain. If you are concerned about pain that
you experience whilst exercise, it is best to discuss this with your local physio. They are experts in
diagnosing your pain and providing you with a plan for management and recovery.