The Popliteal Entrapment Syndrome and Cystic Adventitial Disease of the Popliteal Artery

Andrei Zdoroveac MD*, Peter Stierli MD, Corinne Geppert MD**

* Consultant Dept. Vasc and Endovasc Surgery Aarau – Basle, Switzerland

** Senior Consultant Vascular Centre, Biel, Switzerland

Corresponding author

Peter Stierli, Maiackerweg 6, CH-5042 Hirschthal. hannistierli@hotmail.com

 

Popliteal entrapment syndrome (PAES) is the result of a narrowing of the popliteal artery by surrounding musculo-tendinous structures, causing ischaemic symptoms.

 

Definition and aetiology

The causes of PAES are to be found in consequences of early embryological development. Until the 6^th gestational week, the developing leg is supplied by the sciatic artery which runs ventrally to the popliteal muscles¹Senior H. The development of the arteries of the human lower extremity. American Journal of Anatomy. 1919;25(1):54-95.. The on-going remodelling leads to an involution of the sciatic artery which by the time of birth remains solely as a small artery accompanying the sciatic nerve. The blood supply to the leg is taken over by the femoral artery. During the complex remodelling process, the popliteal segment of the sciatic artery finds its final position in the popliteal fossa, dorsal to the popliteal muscles where it reunites with the femoral artery²DeSesso JM. Vascular ontogeny within selected thoracoabdominal organs and the limbs. Reprod Toxicol. 2017;70:3-20.,³Phng LK, Gerhardt H. Angiogenesis: a team effort coordinated by notch. Dev Cell. 2009;16(2):196-208.. At the same time, the muscles change their positions too, the medial head of the gastrocnaemius muscle rotates from its point of origin, the dorsal aspect of the fibula and tibia, to the medial condyle of the femur⁴Gokkus K, Sagtas E, Bakalim T, Taskaya E, Aydin AT. Popliteal entrapment syndrome. A systematic review of the literature and case presentation. Muscles Ligaments Tendons J. 2014;4(2):141-8.,⁵Love JW, Whelan TJ. POPLITEAL ARTERY ENTRAPMENT SYNDROME. Am J Surg. 1965;109:620-4..

 

Normally, the popliteal artery runs directly between both heads of the gastrocnaemius muscles. Any aberration in this process results in an abnormal position of the popliteal artery with respect to the muscles, causing a compression of the popliteal artery. The muscles may also hypertrophy or fibrose in the popliteal fossa⁶Qazi E, Wilting J, Patel NR, Alenezi AO, Kennedy SA, Tan KT, et al. Arteries of the Lower Limb-Embryology, Variations, and Clinical Significance. Can Assoc Radiol J. 2022;73(1):259-70..

 

Classification

Six different forms of PAES are recognised in the current classification, which is divided into two categories (anatomical and functional). Anatomical PAES develops due to abnormal embryological growth of the blood vessels and the knee muscle⁷Levien LJ, Veller MG. Popliteal artery entrapment syndrome: more common than previously recognized. J Vasc Surg. 1999;30(4):587-98.,⁸Rich NM, Collins GJ, Jr., McDonald PT, Kozloff L, Clagett GP, Collins JT. Popliteal vascular entrapment. Its increasing interest. Arch Surg. 1979;114(12):1377-84.. PAES types 1-5 belong to the anatomical category.

 

1. The popliteal artery runs medial to the normal medial head of the gastrocnaemius muscle.
2. The popliteal artery lies medialy to the aberrant medial head of the gastrocnaemius muscle.
3. An additional muscle strand of the gastrocnaemius muscle originates from the condyle of the femur.
4. The popliteal artery runs ventrally to the popliteus muscle and is trapped between this and the condyle of the femur.
5. Involvement of the popliteal vein.

 

Type 6 is a functional variation with no anatomical abnormality, but is instead a result of a hypertrophic muscle compressing the artery.

 

Figure 1.

 

In the literature, there are increasing reports of anatomical variants which do not fulfil the criteria of the current classification, i.e. aberrant courses of the lateral head of the gastrocnaemius muscle or a prominent lateral condyle of the femur⁹Angeli AA, Angeli DA, Aggeli CA, Mandrekas DP. Chronic lower leg swelling caused by isolated popliteal venous entrapment. J Vasc Surg. 2011;54(3):851-3.,¹⁰Gerkin TM, Beebe HG, Williams DM, Bloom JR, Wakefield TW. Popliteal vein entrapment presenting as deep venous thrombosis and chronic venous insufficiency. J Vasc Surg. 1993;18(5):760-6.,¹¹Wang M, Zhang S, Wu X, Jin X, Zhang J. Popliteal vascular entrapment syndrome caused by variant lateral head of the gastrocnemius muscle leading to pulmonary artery embolism. Clin Anat. 2012;25(8):986-8.. A retrospective analysis of the Mayo Clinic patients showed that 34% of all PAES cases are not defined using the current classification system. Arterial and venous compression can be present as isolated or synchronous findings.

 

To include all variations, the authors proposed a new classification system with seven different types. Types 1-4 and 6 correspond largely to the current classification system, but are supplemented by the add-ons according to the affected blood vessel (artery and/or vein), as well as the location of the pathology in the popliteal fossa (lateral or medial). Type 5 describes a compression of the blood vessel (venous, arterial or combined) by a fibrous band (Fig 2). Very rare cases of compression eg. a prominent condyle of the femur, an arcade in the soleus muscle or an acquired pathology (scar tissue) are collated as Type 7¹²Jayaraj A, Gloviczki P, Duncan AA, Kalra M, Oderich GS, DeMartino RR, et al. Popliteal entrapment syndrome-The case for a new classification. Vascular. 2022;30(2):285-91.. The new classification system is not solely used in the academic setting, but also in the clinical setting when deciding on the diagnosis and treatment for PAES.

 

Figure 2. Red: artery, yellow: peroneal nerve, white: fibrous strand

 

Epidemiology and symptoms

The incidence of PAES is unknown and probably underestimated, as the diagnosis is often missed. Only 5% of all patients with claudication have a PAES¹³Jayaraj A, Gloviczki P, Duncan AA, Kalra M, Oderich GS, DeMartino RR, et al. Popliteal entrapment syndrome-The case for a new classification. Vascular. 2022;30(2):285-91.. The prevalence of PAES is as high as 0,6-3,5% in post mortem studies¹⁴Gibson MH, Mills JG, Johnson GE, Downs AR. Popliteal entrapment syndrome. Ann Surg. 1977;185(3):341-8.. Therefore, the assumption is true that only a small portion of PAES cause symptoms. Important to note is that up to 50% of healthy and asymptomatic people show a significant compression of the popliteal artery when tested in a functional examination. Functional examination without clinical correlation has very little value¹⁵Brown CD, Muniz M, Kauvar DS. Response of the popliteal artery to treadmill exercise and stress positioning in patients with and without exertional lower extremity symptoms. J Vasc Surg. 2019;69(5):1545-51.,¹⁶Erdoes LS, Devine JJ, Bernhard VM, Baker MR, Berman SS, Hunter GC. Popliteal vascular compression in a normal population. J Vasc Surg. 1994;20(6):978-86..

 

As an early and typical symptom, claudication pain in the calves affects young athletes without any cardiovascular risk factors. Other symptoms include a cold foot after exercise, paraesthesia, hypaesthesia and/or loss of strength. Venous compression can lead to acute DVT or chronic venous insufficiency.

 

It is important to distinguish anatomical from functional PAES. If untreated, the continuous compression in anatomical entrapment (aPAES) can cause persistent local damage to the arterial wall (Fig 3) and may cause severe ischaemia of the foot in as many as 24% of patients¹⁷Sinha S, Houghton J, Holt PJ, Thompson MM, Loftus IM, Hinchliffe RJ. Popliteal entrapment syndrome. J Vasc Surg. 2012;55(1):252-62.e30.,¹⁸Zaghloul R, Naouli H, Bouarhroum A. Popliteal Artery Entrapment Syndrome: Report of 2 Critical Aspects Cases. Ann Vasc Surg. 2015;29(8):1662.e7-11..

 

Figure 3. Intimal lesion caused by PAES

Functional entrapment (fPAES) causes claudication pain during exercising, but rarely leads to damage to the vessel wall with ensuing ischaemia.

 

Frequently, patients undergo many unnecessary clinical and orthopaedic investigations including invasive pressure monitoring of the muscle compartments. Rarely, fPAES can be present in combination with pathologically elevated intra-compartmental pressure which may lead to unnecessary fasciotomy. In a retrospective analysis by Kedar et al. of 36 patients (56 legs), eleven (35%) had been mistakenly treated with fasciotomy by the time the diagnosis of PAES was made¹⁹Lavingia KS, Dua A, Rothenberg KA, Fredericson M, Lee JT. Surgical management of functional popliteal entrapment syndrome in athletes. J Vasc Surg. 2019;70(5):1555-62..

 

In a few cases, an unrecognized PAES has been treated by femoro-popliteal stenting. Due to continuous and persistent compression, the stents can fracture. Such cases are rarely reported on in the literature, however, a much higher incidence may be assumed²⁰Wittig T, Steiner S, Schmidt A, Scheinert D, Branzan D. Popliteal Artery Entrapment Syndrome: A Rare Cause of Interwoven Nitinol Stent Fracture After Femoropopliteal Interventions. JACC Case Rep. 2022;4(7):424-8..

 

Many patients share a long history of erroneous investigations and examinations until the correct diagnosis of a PAES is finally be made²¹Sinha S, Houghton J, Holt PJ, Thompson MM, Loftus IM, Hinchliffe RJ. Popliteal entrapment syndrome. J Vasc Surg. 2012;55(1):252-62.e30.. Far more frequently, it is assumed there is a muscular cause in young and often athletic people when they present with (bilateral) leg pain.

 

In one of the largest retrospective analysis between 2010 and 2020, 38 patients were analysed²²Deveze E, Bruneau A, Hersant J, Ammi M, Abraham P, Picquet J. Popliteal Entrapment Syndrome: Diagnostic, Surgical Management, and Short-Term Results of a Ten-Year Experience. Ann Vasc Surg. 2023;88:139-44.. The demographic characteristics simulate the historical findings. Two thirds are male with a median age of 24.7 +/-9 years. The majority, 92%, exercise regularly; 75-80% present with bilateral problems²³Lavingia KS, Dua A, Rothenberg KA, Fredericson M, Lee JT. Surgical management of functional popliteal entrapment syndrome in athletes. J Vasc Surg. 2019;70(5):1555-62..

 

There has been no improvement over the years when looking at the 2 year delay on average from the start of the symptoms to the final diagnosis²⁴Corneloup L, Labanère C, Chevalier L, Jaussaud J, Mignot A, Gencel L, et al. Presentation, diagnosis, and management of popliteal artery entrapment syndrome: 11 years of experience with 61 legs. Scand J Med Sci Sports. 2018;28(2):517-23..

 

1. d) Diagnosis

The patient’s history can often be typical; on clinical examination, suspected PAES can be confirmed. All pulses in the lower extremities must be examined. Then the patient is asked to perform repetitive dorsal and plantar flexion. In PAES, the pulses diminish or disappear completely. Furthermore, arterial measurements (ankle brachial index= ABI) and in particular, Duplex ultrasonography in flexion and extension may be diagnostic. A decrease in ABI in flexion by 30-50% supports the suspected diagnosis of PAES²⁵Gaunder C, McKinney B, Rivera J. Popliteal Artery Entrapment or Chronic Exertional Compartment Syndrome? Case Rep Med. 2017;2017:6981047.. In Duplex sonography, the pattern of flow in the artery can be examined in passive flexion and extension of the foot, as well as in active flexion with, and without resistance (Fig 4).

 

With the above signs, or an arterial occlusion in a young patient, PAES may be suspected. Corneloup et al. recommend a Duplex ultrasonography as primary investigation. For the diagnosis of PAES, the specificity reached 76% when finding a dynamic occlusion of the popliteal artery on the Duplex ultrasound scan²⁶Corneloup L, Labanère C, Chevalier L, Jaussaud J, Mignot A, Gencel L, et al. Presentation, diagnosis, and management of popliteal artery entrapment syndrome: 11 years of experience with 61 legs. Scand J Med Sci Sports. 2018;28(2):517-23.. Unfortunately, the sensitivity of Duplex ultrasound scan was not estimated in this study. Therefore, it remains unclear whether a PAES can safely be excluded when the artery is not completely occluded in provocation testing²⁷Dyer KT, Hogrefe CP. Don’t Just Blame it on the Veins: An Update on Vascular Exertional Limb Pain. Curr Sports Med Rep. 2018;17(10):347-53..

 

Figure 4. Provocation test: oscillography at rest (left) and in dorsiflexion (right)

 

The pathological findings on Duplex ultrasound scan should be confirmed by a dynamic MRI or CT scan. These investigations may also be performed in patients with a normal ultrasound scan investigation if PAES is still suspected²⁸Deveze E, Bruneau A, Hersant J, Ammi M, Abraham P, Picquet J. Popliteal Entrapment Syndrome: Diagnostic, Surgical Management, and Short-Term Results of a Ten-Year Experience. Ann Vasc Surg. 2023;88:139-44.. For many years, diagnostic angiography with provocation testing was thought to be the gold standard. However, dynamic CT scan or MRI are superior when examining the anatomical location of the blood vessels in relation to the surrounding muscles/soft tissue²⁹Anil G, Tay KH, Howe TC, Tan BS. Dynamic computed tomography angiography: role in the evaluation of popliteal artery entrapment syndrome. Cardiovasc Intervent Radiol. 2011;34(2):259-70.,³⁰Ring DH, Jr., Haines GA, Miller DL. Popliteal artery entrapment syndrome: arteriographic findings and thrombolytic therapy. J Vasc Interv Radiol. 1999;10(6):713-21.. Normally, the popliteal vessels are surrounded only by fatty tissue. Any other tissue, muscles or connective tissue-like structures, in direct contact with the blood vessels can compress the artery in provocation testing and is highly suspicious of PAES. In the case of a fPAES, a hypertrophic gastrocnaemius muscle can easily be identified on an MRI scan³¹Erdoes LS, Devine JJ, Bernhard VM, Baker MR, Berman SS, Hunter GC. Popliteal vascular compression in a normal population. J Vasc Surg. 1994;20(6):978-86.,³²Liu Y, Sun Y, He X, Kong Q, Zhang Y, Wu J, et al. Imaging diagnosis and surgical treatment of popliteal artery entrapment syndrome: a single-center experience. Ann Vasc Surg. 2014;28(2):330-7.. One of the disadvantages of a dynamic MRI scanning is motion artefact, especially if a patient develops ischaemic pain during the investigation³³Pillai J, Levien LJ, Haagensen M, Candy G, Cluver MD, Veller MG. Assessment of the medial head of the gastrocnemius muscle in functional compression of the popliteal artery. J Vasc Surg. 2008;48(5):1189-96.. A further disadvantage of the MRI scan is the difficulty in judging the degree of stenosis in comparison with angiography, especially for moderate stenoses, i.e. < 50%³⁴Kim HK, Shin MJ, Kim SM, Lee SH, Hong HJ. Popliteal artery entrapment syndrome: morphological classification utilizing MR imaging. Skeletal Radiol. 2006;35(9):648-58..

 

Some authors recommend a digital subtraction angiogram (DSA) in the presence of a popliteal occlusion (Fig 5). The DSA is superior to other investigative tools when identifying peripheral embolisation. In such cases the treatment strategy may alter, as pre-operative thrombolysis may be an option³⁵Simsek E, Bugra O, Teber MA, Katircioglu SF. What should be the first treatment of popliteal artery entrapment syndrome. Ann Thorac Cardiovasc Surg. 2014;20(2):169-72.. The role of intravascular ultrasound (IVUS) remains unclear, but it may be a tool for the future³⁶Lavingia KS, Dua A, Rothenberg KA, Fredericson M, Lee JT. Surgical management of functional popliteal entrapment syndrome in athletes. J Vasc Surg. 2019;70(5):1555-62.,³⁷Causey MW, Singh N, Miller S, Quan R, Curry T, Andersen C. Intraoperative duplex and functional popliteal entrapment syndrome: strategy for effective treatment. Ann Vasc Surg. 2010;24(4):556-61.,³⁸Chou HH, Wu IH, Yeh KH, Ko YL, Huang HL. The Usefulness of Intravascular Ultrasound in Popliteal Artery Entrapment Syndrome. JACC Cardiovasc Interv. 2019;12(20):2110-1..

 

Figure 5. Angiography at rest (left) and in plantar flexion (right)

 

Therapy

The surgical treatment strategy depends on the clinical findings and the underlying pathology ie. abnormal anatomy. In many cases, resection of the aberrant musculo-tendinous structure is sufficient. If there is severe damage to the arterial wall such as intimal hyperplasia, dissection, thrombosis or aneurysm, reconstruction of the artery by angioplasty or bypass grafting may be required³⁹Grimm NL, Danilkowicz R, Shortell C, Toth AP. Popliteal Artery Entrapment Syndrome. JBJS Rev. 2020;8(1):e0035.. If patients present with an acute limb ischaemia, then the treatment options need to fulfil the requirements/recommendations of the Rutherford criteria: in stage I-IIa, early elective surgery may be planned. In more severe stages (IIb) an emergency procedure has to be performed. In patients with an acute ischaemia of less than two weeks’ duration, an endovascular thrombectomy or thrombolysis may be considered⁴⁰Simsek E, Bugra O, Teber MA, Katircioglu SF. What should be the first treatment of popliteal artery entrapment syndrome. Ann Thorac Cardiovasc Surg. 2014;20(2):169-72.,⁴¹di Marzo L, Cavallaro A, Sciacca V, Mingoli A, Tamburelli A. Surgical treatment of popliteal artery entrapment syndrome: a ten-year experience. Eur J Vasc Surg. 1991;5(1):59-64.,⁴²Wang X, Zhang H, Yan J, Lu Z. Successful endovascular treatment of popliteal artery entrapment syndrome: a case report with 3-years follow-up. J Thromb Thrombolysis. 2017;44(1):112-7..

 

Endovascular recanalisation alone is, however, not the definitive treatment strategy, as long as the underlying pathology (compression of the vessel) has not been treated.

 

The ideal surgical approach for the treatment of PAES is from behind, with the patient prone. Type I and II PAES is treated by myotomy of the medial head of the gastrocnaemius muscle, type II by resection of the accessory fibrous strand. Alternatively, a medial release of the medial head of gastrocnaemius muscle (Turnipseed operation) may be performed⁴³Turnipseed WD. Functional popliteal artery entrapment syndrome: A poorly understood and often missed diagnosis that is frequently mistreated. J Vasc Surg. 2009;49(5):1189-95.. In type IV PAES, the popliteal artery remains in the ventral position lying on the popliteal muscle. In such cases, the myotomy of the popliteus muscle is sufficient, which enables the artery to lie more dorsally. A reconstruction of the muscle may be performed. An identical approach is recommended for type V PAES, to decompress the popliteal vein. Myotomy alone has excellent results with a primary patency of almost 100% at 1-5 year follow-up⁴⁴Lejay A, Delay C, Georg Y, Gaertner S, Ohana M, Thaveau F, et al. Five Year Outcomes of Surgical Treatment for Popliteal Artery Entrapment Syndrome. Eur J Vasc Endovasc Surg. 2016;51(4):557-64..

 

If the popliteal artery is chronically occluded, or there is an intimal lesion or aneurysm, a reconstruction by thrombectomy and patching or by venous bypass or interposition grafting is needed. The results of bypass grafting have the best patency rates⁴⁵Carneiro Júnior FCF, Carrijo E, Araújo ST, Nakano LCU, de Amorim JE, Cacione DG. Popliteal Artery Entrapment Syndrome: A Case Report and Review of the Literature. Am J Case Rep. 2018;19:29-34.,⁴⁶Skeik N, Thomas TM, Engstrom BI, Alexander JQ. Case report and literature review of popliteal artery entrapment syndrome. Int J Gen Med. 2015;8:221-5..

 

If the great saphenous vein is needed for the reconstruction, then the prone position enables the harvesting of the vein in the thigh to below the knee. Stenting/angioplasty are not recommended, as the remaining and persistent compression will lead to stent stenosis or fracture⁴⁷di Marzo L, Cavallaro A, O’Donnell SD, Shigematsu H, Levien LJ, Rich NM. Endovascular stenting for popliteal vascular entrapment is not recommended. Ann Vasc Surg. 2010;24(8):1135.e1-3.. A fPAES may be treated by repetitive botulinum toxin injections.

 

1. f) Results

The first follow-up should be performed 6-12 weeks after surgery with Duplex ultrasound and (ABI). In the study of Deveze at al. four patients (6%) had haematomas after decompression and bypass surgery, and eight (13%) had delayed wound healing⁴⁸Deveze E, Bruneau A, Hersant J, Ammi M, Abraham P, Picquet J. Popliteal Entrapment Syndrome: Diagnostic, Surgical Management, and Short-Term Results of a Ten-Year Experience. Ann Vasc Surg. 2023;88:139-44.. One patient developed an acute occlusion of the anterior tibial artery with temporary symptoms of an acute subcritical ischaemia. After treating with heparin and aspirin the symptoms ebbed off completely. The primary patency rate in the distal popliteal artery was 100%. These figures are in contrast to data from the literature, where almost 30% of patients developed recurrent stenosis/occlusion. The reason might be the wide variation in these patients with such a rare disease.

 

In a retrospective analysis by Kedar et al of a group of treated athletes with fPAES, 78% were able to return to their previous performance before the surgery.

 

In the largest cohort to date of non-athletes (Turnipseed et al), 94% of patients returned back to their daily activities without any restrictions⁴⁹Turnipseed WD. Functional popliteal artery entrapment syndrome: A poorly understood and often missed diagnosis that is frequently mistreated. J Vasc Surg. 2009;49(5):1189-95..

 

Decompression plays an essential role in the treatment of an anatomical PAES, however, there is a risk of recurrence. In up to 9,2% of cases, there is a recurrence of symptoms in fPAES when treated by surgery alone⁵⁰Shahi N, Arosemena M, Kwon J, Abai B, Salvatore D, DiMuzio P. Functional Popliteal Artery Entrapment Syndrome: A Review of Diagnosis and Management. Ann Vasc Surg. 2019;59:259-67.. In a retrospective analysis, recurrent symptoms less more common after fPAES treated by myectomy (27%), than in patients treated for aPAES, 83%⁵¹Clemens MS, Scott DJ, Watson JD, Wang LC, Hislop SJ, Arthurs ZM. A diagnostic evolution: surgical experience with popliteal artery entrapment syndrome at a military tertiary referral center. Ann Vasc Surg. 2015;29(6):1078-83..

 

An alternative to surgery for fPAES, is the use of botulinum Toxin A (BTX-A) injections. By injecting into the gastrocnaemius muscle, it relaxes and thereby reduces the symptoms. One to three injections (100MU) of BTX-A induce a successful relaxation in 82.9% of patients. The effect lasts for 3-6 months. Repeat injections have no known side-effects and therefore present a safe alternative to surgery⁵²Shahi N, Arosemena M, Kwon J, Abai B, Salvatore D, DiMuzio P. Functional Popliteal Artery Entrapment Syndrome: A Review of Diagnosis and Management. Ann Vasc Surg. 2019;59:259-67.,⁵³Hislop 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):1241-8..

 

In a case report, Murphy⁵⁴Murphy M, Charlesworth J, Koh E. The effects of Botulinum Toxin injection in an elite sportsman with Functional Popliteal Artery Entrapment Syndrome: A case report. Phys Ther Sport. 2017;27:7-11. describes a professional sportsman with a fPAES. After a significant drop in performance, he was able to return to his baseline level of performance only 4 weeks after BTX-A injection. On ultrasound examination a shrinkage of the medial head of the gastrocnaemius muscle was seen with a significant increase in the diameter of the artery. In a performance analysis at the end of the season, a significant increase in the overall covered running distance was registered⁵⁵Murphy M, Charlesworth J, Koh E. The effects of Botulinum Toxin injection in an elite sportsman with Functional Popliteal Artery Entrapment Syndrome: A case report. Phys Ther Sport. 2017;27:7-11..

 

Shahi et al recommend a BTX-A injection as part of the diagnostic work-up. This is especially recommended in the event of a CT or MRI scan showing a dynamic compression of the artery with no signs of morphological change to the vessel wall, where it is impossible to differentiate between a fPAES and an aPAES. A diagnostic injection may help in differentiating between the two. If the symptoms improve, fPAES is more likely. Therefore, repeat BTX-A injections, as well as an operation may be possible alternatives. In the absence of any improvement, it is more likely to be an aPAES which should be treated by surgery⁵⁶Shahi N, Arosemena M, Kwon J, Abai B, Salvatore D, DiMuzio P. Functional Popliteal Artery Entrapment Syndrome: A Review of Diagnosis and Management. Ann Vasc Surg. 2019;59:259-67..

 

Summary

PAES is a relatively rare, non-atheromatous arterial disease, generally seen in young and healthy people. As the diagnosis may be delayed for some time, there can be quite dramatic and prolonged courses. General practitioners, orthopaedic surgeons and sport medicine specialists need to be made aware of the syndrome. It is diagnosed by ultrasound, MR, CT scan or angiography at rest and on provocation testing with dorsal and plantar extension of the foot. PAES can be classified into two groups, an anatomical and a functional group. In aPAES with aberrant musculo-tendinous structures, surgery is the primary treatment option. This is especially the case in the absence of vessel wall lesions. Alternatively, the treatment of stenosis or occlusions includes the reconstruction of the artery by bypass or interposition venous grafting. Endovascular options are not recommended as first line treatment, only as an adjunct to surgery (thrombolysis). In the case of a fPAES caused by muscular hypertrophy and in the absence of any anatomical abnormality, the alternatives are surgical release and/or BTX-A injections.

Summary

Cystic adventitial disease (CAD) of the popliteal artery is a rare condition manifesting in young to middle-aged people with varying intermittent claudication. The cysts may also occur in veins. Treatment consists of removing the frequently multiloculated cysts either by replacement of the artery with bypass-graft or local cyst excision.

 

Figure 6. Artists interpretation of a cystic adventitial disease in the popliteal artery

 

History and Pathophysiology

The condition was first described in 1947¹Atkins HJ, Key JA. A case of myxomatous tumour arising in the adventitia of the left external iliac artery; case report. Br J Surg. 1947;34(136):426.. The authors described a female patient with increasingly painful claudication of her thigh and calf with progressive swelling above the inguinal ligament. The cause for this manifestation was a ganglion of the external iliac artery, found intraoperatively.

 

In 1987, Ishikawa described 195 cases in the world literature²Ishikawa K. Cystic adventitial disease of the popliteal artery and of other stem vessels in the extremities. Jpn J Surg. 1987;17(4):221-9.. In 39 cases, the cystic adventitial disease was not manifest in the popliteal artery, but in other arteries and veins, usually the external iliac artery and vein. The latter is closely adjacent to the hip joint, causing atypical hip pain. Similar findings were noted in a literature review by Desy et al in 2014³Desy NM, Spinner RJ. The etiology and management of cystic adventitial disease. J Vasc Surg. 2014;60(1):235-45, 45.e1-11.. Rarely, the condition can affect children⁴Gokkus K, Sagtas E, Bakalim T, Taskaya E, Aydin AT. Popliteal entrapment syndrome. A systematic review of the literature and case presentation. Muscles Ligaments Tendons J. 2014;4(2):141-8..

 

The cause of the formation is unknown. An underlying cause, such as a connective tissue disorder, has never been observed in a patient with cystic adventitial disease. Neither has a generalized manifestation, nor bilateral cysts been described⁵Haid SP, Conn J, Jr., Bergan JJ. Cystic adventitial disease of the popliteal artery. Arch Surg. 1970;101(6):765-70.,⁶Leaf G. Addendum: Amino-acid analysis of protein present in a popliteal artery cyst. The British Medical Journal. 1967;3(5562):415-.. A trauma-related cause is unlikely⁷Haid SP, Conn J, Jr., Bergan JJ. Cystic adventitial disease of the popliteal artery. Arch Surg. 1970;101(6):765-70..

 

One theory is that mucin-producing cells are “lost” in the adventitia and form cysts with mucinous content⁸Love JW, Whelan TJ. POPLITEAL ARTERY ENTRAPMENT SYNDROME. Am J Surg. 1965;109:620-4. (5).The content of the cysts is not unlike that of a ganglion⁹Leaf G. Addendum: Amino-acid analysis of protein present in a popliteal artery cyst. The British Medical Journal. 1967;3(5562):415-.. Occasionally, there are connections found between the cyst and a joint. In a case report concerning siblings with CAD, there have been discussions regarding a genetic component¹⁰Ching-Yee Chan M, Cornwall J, Ilonzo N, McKinsey J. Cystic adventitial disease of the popliteal vein and artery in siblings. J Vasc Surg Cases Innov Tech. 2021;7(3):545-8.. Most likely, in such cases, the cysts originate from the synovial tissue of the neighbouring joint and spread via side branches into the vessel wall¹¹Spinner RJ, Desy NM, Agarwal G, Pawlina W, Kalra M, Amrami KK. Evidence to support that adventitial cysts, analogous to intraneural ganglion cysts, are also joint-connected. Clin Anat. 2013;26(2):267-81.,¹²Hao H, Ishibashi-Ueda H, Nishida N, Kawakami R, Tsukamoto Y, Tsujimoto M, et al. Distribution of myofibroblast and tenascin-C in cystic adventitial disease: comparison with ganglion. Pathol Int. 2013;63(12):591-8.,¹³Flessenkaemper I, Müller KM. Early recurrence of cystic adventitial disease in a vein graft after complete resection of the popliteal artery. Vasa. 2014;43(1):69-72..

 

Symptoms

The classical symptoms include claudication pain or acute ischaemia in patients aged 30-50yrs. Frequently, the foot pulses are weakly palpable. Typically, there are symptom-free episodes followed by symptomatic phases, possibly resulting from variable tension in the cysts. The affected patients are not usually typical vascular patients and do not have the normal risk factors for arteriosclerosis. The symptoms can mimic those of an entrapment-syndrome which makes this an important differential diagnosis to consider¹⁴Smith JL, Hariri N, Oriowo B, Lurie F. Cystic adventitial disease of the popliteal artery presenting with features of entrapment syndrome. J Vasc Surg Cases Innov Tech. 2020;6(1):75-9..

 

Diagnosis

Most importantly, the diagnosis of CAD and popliteal entrapment syndrome must be considered when treating a young patient with atypical and varying forms of claudication pain.

 

Nowadays, conventional angiography is redundant in the diagnosis of CAD. in the past the classical angiography sign of the narrowing stenosis is described as the Scimitar sign (Fig 7).

 

Figure 7. Elongated stenosis of the popliteal artery caused by an adventitial cyst.

 

A Duplex ultrasound scan offers a highly sensitive and preferred method for diagnosing the stenosis as well as the cysts. These hypo-echogenic structures in the vessel wall cause a narrowing and consequently an increase in blood flow (Fig 8).

Figure 8. Typical Duplex ultrasound scan of cystic adventitial disease of the popliteal artery.

 

MR and CT angiography are equally suitable for diagnosing CAD (Fig 9). Rarely the diagnosis is made during investigation of a patient with popliteal occlusion causing acute ischaemia.

 

Figure 9. MRA with a compressing cyst in the popliteal artery (marked with +)

 

Treatment

The removal of the cyst forms the principle step in treating CAD.

 

A simple ultrasound guided puncture with aspiration of the cyst offers rarely long-lasting results, as the cysts are often multiloculated¹⁵Desy NM, Spinner RJ. The etiology and management of cystic adventitial disease. J Vasc Surg. 2014;60(1):235-45, 45.e1-11.,¹⁶Seo H, Fujii H, Aoyama T, Sasako Y. A Case of Adventitial Cystic Disease of the Popliteal Artery Progressing Rapidly after Percutaneous Ultrasound-guided Aspiration. Ann Vasc Dis. 2014;7(4):417-20.. Nor is an endovascular approach (stenting or angioplasty) recommended as the pathological process is purely extra-luminal¹⁷Mertens R, Bergoeing M, Mariné L, Valdés F, Krämer A. Endovascular treatment of cystic adventitial disease of the popliteal artery. Ann Vasc Surg. 2013;27(8):1185.e1-3.,¹⁸Paravastu SC, Regi JM, Turner DR, Gaines PA. A contemporary review of cystic adventitial disease. Vasc Endovascular Surg. 2012;46(1):5-14..

 

The most frequently used treatment is replacement of the diseased vessel or bypass grafting¹⁹Desy NM, Spinner RJ. The etiology and management of cystic adventitial disease. J Vasc Surg. 2014;60(1):235-45, 45.e1-11.,²⁰Tsolakis IA, Walvatne CS, Caldwell MD. Cystic adventitial disease of the popliteal artery: diagnosis and treatment. Eur J Vasc Endovasc Surg. 1998;15(3):188-94.. Ideally, especially in the area of the knee joint, the use of autologous vein is recommended as first-line option. This is also the case when operating in an emergency. The medial approach to the popliteal artery may be used for a bypass procedure, but a posterior approach allows visualization of the whole popliteal artery, with direct replacement of the diseased section.

 

Posterior approach

There is no absolute indication for replacing the affected part of the popliteal artery as complete removal of the cysts can be achieved over a long distance by local excision²¹Stierli P, Mauch J, Koella C, Huber A, Eugster T, Gürke L. Circumferential removal of the adventitia for cystic degeneration of the popliteal artery. Br J Surg. 2005;92(1):56-7.,²²Kikuchi S, Sasajima T, Kokubo T, Koya A, Uchida H, Azuma N. Clinical results of cystic excision for popliteal artery cystic adventitial disease: long-term benefits of preserving the intact intima. Ann Vasc Surg. 2014;28(6):1567.e5-8..As long as the cystic area is confined to the popliteal artery it can be treated via a posterior approach. The diseased area of the artery can be dissected and prepared. The affected pat of the adventitia including all cysts needs to be removed circumferentially up to the external elastic lamina; it is normally not too difficult to define the correct layer. Arterial branches are ligated (Fig 10).

 

Figure 10. Posterior approach to the popliteal artery and excision of CAD.

Figure 10a. preparation of the diseased part of the artery

 

Figure 10b. Opened cysts with jelly-like content

 

Figure 10c. Preparation of the diseased adventitia for excision

 

Figure 10d. This image shows the preparation of the diseased adventitia. The vessel is underlain with foil.

 

Figure 10e. This image shows a connection between knee joint and the diseased artery.

 

Outcome

The long term results for replacements of the popliteal artery with autologous vein are very good²³Desy NM, Spinner RJ. The etiology and management of cystic adventitial disease. J Vasc Surg. 2014;60(1):235-45, 45.e1-11.,²⁴Tsolakis IA, Walvatne CS, Caldwell MD. Cystic adventitial disease of the popliteal artery: diagnosis and treatment. Eur J Vasc Endovasc Surg. 1998;15(3):188-94.. Late results correspond to those of autologous bypass surgery for ischaemia and are strongly dependent on the quality of the vein. Unfortunately, in 9% of treated cases the cysts recur which warrants a long term follow up with Duplex ultrasound²⁵Desy NM, Spinner RJ. The etiology and management of cystic adventitial disease. J Vasc Surg. 2014;60(1):235-45, 45.e1-11.. This happens more likely after local surgery.

 

The results of local excision of CAD published so far are excellent. In the long term there is no sign of vessel wall weakening, no recurrent cysts nor stenosis due to intimal hyperplasia²⁶Stierli P, Mauch J, Koella C, Huber A, Eugster T, Gürke L. Circumferential removal of the adventitia for cystic degeneration of the popliteal artery. Br J Surg. 2005;92(1):56-7.,²⁷Kikuchi S, Sasajima T, Kokubo T, Koya A, Uchida H, Azuma N. Clinical results of cystic excision for popliteal artery cystic adventitial disease: long-term benefits of preserving the intact intima. Ann Vasc Surg. 2014;28(6):1567.e5-8.. Mandatory for this success is the complete removal of the diseased segment of adventitia including all cysts.

 

Venous cysts

Cystic adventitial disease of the veins occurs mostly in the external iliac vein or femoral vein. Treatment is more complex. As a rule, the severely diseased segment of the vein has to be replaced completely by autologous vein²⁸Kim E, Lamb KM, Whisenhunt AK, Ayad M, Farber J, DiMuzio P. Venous cystic adventitial disease of the common femoral vein. J Vasc Surg Venous Lymphat Disord. 2014;2(2):194-6.,²⁹Correia R, Gião N, Bento R, Garcia R, Camacho N, Ferreira ME. Cystic Adventitial Disease of the Popliteal Vein, a Rare Cause of Lower Limb Deep Vein Thrombosis. EJVES Vasc Forum. 2022;54:75-8.,³⁰Biggs JH, Kalra M, Skinner JA, DeMartino RR. Adventitial cystic disease of the common femoral vein: an unusual cause of lower extremity swelling and review of the literature. J Vasc Surg Cases Innov Tech. 2021;7(4):610-6.. To achieve the required diameter, a spiral graft of the great saphenous vein, or the contralateral superficial femoral vein may be used.