Popliteal Artery Entrapment: Eight Years Experience
Article Outline
Objectives
We present our experience with popliteal artery entrapment syndrome (PAES).
Patients and methods
12 cases of PAES were diagnosed in 8 patients with an average age of 38 years. Symptoms consisted of intermittent claudication in 6 limbs; acute ischemia in 3 limbs and 2 were asymptomatic. Diagnoses were made via angio MRI. Type II, III, V and functional entrapments were found. We used a posterior approach in 6 cases and a medial approach in 4 cases. Seven popliteal-popliteal bypasses with reversed saphenous veins, one femoro-popliteal bypass with saphenous vein, one popliteal-tibial-peroneal trunk bypass and one angioplasty with a vein patch were performed. In all cases, decompressions along with myotomy was performed.
Results
An early bypass occlusion plus one more 5 years later occurred. No amputations were needed.
Conclusions
PAES is a pathological entity that should be suspected in young adults presenting with intermittent claudication without cardiovascular risk factors. MRA is the most complete diagnostic examination for PAES. Surgical treatment is recommended for types I to V and for symptomatic functional syndromes.
Keywords: Popliteal entrapment, Claudication-young adult, MRI, Aneurysm, Critical ischaemia
Background
The first case of popliteal artery entrapment was reported in 1879 by Anderson Stuart1 although it was not until 1959 that Hamming performed the first popliteal artery surgical decompression in Holland.2 Love and Whelan coined the term popliteal artery entrapment syndrome (PAES) in 1965.3
PAES is a low prevalence pathology that causes intermittent claudication in healthy young adults.4 It involves a defect in embryonic development at the level of the popliteal fossa, which, as a consequence, produces a muscular compression of the popliteal artery. Functional entrapment is more characteristically seen in athletes with large muscle development.
The normal popliteal artery in adults is the product of the fusion of multiple embryonic elements: the ramus communicans superius, arteria ischiadica, arteria poplitea superficialis and the arteria interossea. The deep popliteal artery, which is located medial and deep to the popliteal muscle, is obliterated and disappears during embryonic development. PAES could be the result of anomalous development of the popliteal artery caused by perpetuation of the deep popliteal artery or due to excessive cranial migration of the medial head of the gastrocnemius muscle at its femoral insertion.6, 7
Multiple classifications of PAES have been described,8 but the most widely accepted recognizes five types of popliteal entrapment:9 Type I: The gastrocnemius muscle is inserted normally, while the popliteal artery takes an exaggerated loop, coursing medially to the insertion of the head of the gastrocnemius muscle; Type II: The medial head of the gastrocnemius is inserted more laterally than normal, thus the popliteal artery, although following a relatively normal trajectory, courses medially and under the muscle insertion; Type III: The popliteal artery gets compressed by an anomalous fibrosis band of the gastrocnemius that is inserted more laterally than the rest of the muscle; Type IV: The popliteal artery is entrapped by the popliteal muscle or by a fibrous band at the same localization; and Type V: Includes all of the above variants in which the vein is also found to be trapped (Fig. 11).
Fig. 1
Ultrasound-doppler with popliteal artery dilatation.
Another type of functional nerve and vascular popliteal entrapment exists, in absence of any kind of anatomical abnormality, and has been described among athletes with largely developed muscles.10 It is believed that the popliteal nerve, vein and arteries could be compressed either by the hypertrophic soleus muscle against the tibial condyle or by excessive development of the plantaris muscle.5
Patients and Methods
We studied, retrospectively, 12 cases of PAES in a total of 8 patients in our hospital over a period of eight years (from 1998 to 2005). These cases were predominantly male (male: female ratio 6:2), with an age ranging from 24 and 63 years (mean 38 years). Within this patient group PAES began with different degrees of intermittent claudication in six limbs, three exhibited episodes of acute ischemia, one only had oedema, and two cases were asymptomatic. The case was diagnosed upon a coincidental finding during popliteal aneurysm surgery (via posterior approach). In four cases, PAES was bilateral. With regards to the existence of cardiovascular risk factors at the time of the diagnosis, only two patients were smokers. Two highlighted cases include a woman in her fourth month of pregnancy and an elderly patient with high blood pressure (Table 1).
Table 1.
| Case N | Sex | Age | Side | Risk factors | Symptoms |
|---|---|---|---|---|---|
| 1 | E.C.A. male | 43 | Bilateral | Ex-smoker | LLL: Acute ischemia |
| RLL: IIC | |||||
| 2 | A.M.S. male | 63 | RLL | High blood arterial pressure | Un-expected finding: Pop An |
| RLL: Aedema | |||||
| 3 | V.E.H. female | 24 | RLL | Smoker | Acute ischemia |
| Exercise | |||||
| 4 | I.E.E. male | 37 | Bilateral | No | LLL: IIC |
| RLL: Asymptomatic | |||||
| 5 | B.M.B. female | 31 | RLL | No (pregnant) | Acute ischemia |
| 6 | O.L.S. male | 27 | Bilateral | No | EIC: Bilateral |
| Exercise | |||||
| 7 | S.S.G. male | 43 | Bilateral | No | RLL: Asymptomatic |
| LLL: IIC | |||||
| 8 | C.K.N male | 39 | RLL | Smoker | Long distances IIC |
A positive stress test consists of a decrease in the ankle-arm index under provocation (dorsiflexion and forced plantar flexion). Ankle/arm systolic blood pressure indices were less than 1 in the 7 extremities with an occluded popliteal artery and in one with a patent popliteal artery (n # 6). They were greater than 1 in the remainder limbs. There was a non-significant decrease noted upon provocative maneuvers. All patients underwent a Doppler ultrasonography test of the posterior tibial artery and dorsalis pedis. The duplex ultrasonographic test with provocative maneuvers showed a decreased peak systolic flow in cases of previously normal ankle/arm index and a patent popliteal artery. In the cases of occluded artery, the duplex was not useful to suspect PAES and only detected the occlusion the popliteal artery. In the case of the pregnant woman, a fusiform arterial dilatation was found (Fig. 1). With provocative dorsiflexion and forced plantar flexion we saw a decrease peak systolic blood flow and a stenosis of 70%. In the study of a leg with oedema (n#2), duplex detected an popliteal artery aneurysm which compressed the popliteal vein. Provocative maneuvers were not performed because PAES was not suspected. An magnetic resonance angiogram (MRA) was also performed at the aortic and lower limb territories in all patients (with the exception of one patient n°2 diagnosed unexpectedly during surgery for a popliteal aneurysm). The MRI showed existing muscle abnormalities, allowing the classification of different types of PAES. MRA can demonstrate bilateral abnormalities such as medial deviations of the popliteal artery (type II) (Fig. 2), concomitant arterial injury, and will demonstrate the pre-existent run-off (Fig. 3, Fig. 4, Fig. 5). The lower limb digital subtraction arteriography test was performed in those cases where limb vascularization was not seen clearly with the MRA and in one case first presented with acute ischemic events.
Fig. 2
Arterial lesions and medial deviation of the popliteal artery.
Fig. 3
Medial separation of the popliteal artery due to interposition of the gastrocnemius muscular fascicle.
Fig. 4
Anomalous insertion of the internal gastrocnemius muscle.
Fig. 5
Angio MRI showing bilateral popliteal lesions and distal vascularization.
Surgery
Surgical repair was elected as the first treatment option, except in one case of poor distal run off. One patient with a bilateral syndrome rejected the option of further contralateral surgical intervention after previous repair of the ipsilateral limb. Two different approaches were utilized, selected on the basis of PAES classification and the extent of arterial injuries. A medial approach to the popliteal artery (4 cases, Fig. 6) was performed in those cases with functional entrapment and in one case where an anastomosis on the infrapopliteal vessels (tibio-peroneal trunk) was required. A posterior approach (6 cases, Fig. 7) was performed in the rest of cases where the anatomical abnormality could be clearly identified (Table 2).
Fig. 6
Left lower limb (LLL): Popliteal-tibioperoneal trunk bypass; Right lower limb (RLL): segmental obstruction of popliteal artery.
Fig. 7
Anomalous insertion of a fascicle at the internal gastrocnemius muscle.
Table 2.
| Basal AAR | PO AAI | Basal pulses | PO pulses | Classification | Surgery | Outcome | |
|---|---|---|---|---|---|---|---|
| 1 | 0.25 | >1 | Fe+ R- | PDP | Functional | Pop-pop Bp | Asymptomatic |
| Medial approach | |||||||
| 1 | 0.55 | >1 | Fe+ R- | PDP | Functional | Pop-pop Bp | Bp occlusion 5 y. later |
| Medial approach | 500 m IC | ||||||
| 2 | >1 | >1 | PDP | PDP | V (*) | Pop-pop Bp | Asymptomatic |
| Posterior approach | |||||||
| 3 | 0.3 | 0.66 | Fe+ R- | NR | Functional | Fem-pop Bp | Early occlusion |
| Medial approach | IC> 1Km | ||||||
| 4 | >1 | >1 | PDP | PDP | II | Pop-pop Bp | Asymptomatic |
| Posterior approach | |||||||
| 4 | 0.49 | 0.88 | Fe+ Pop+ R- | Fe+ Pop+ R- | II | Popliteal plastia w. patch | IC>2Km |
| Posterior approach | |||||||
| 5 | 0.50 | >1 | Fe+ R- | PDP | III | Pop-pop Bp | Asymptomatic |
| Posterior approach | |||||||
| 6 | 0.81 | - | PDP | NC | II | No surgery | IC with excercise |
| 6 | 0.77 | >1 | Fe+ R- | PDP | II | Pop-tpt Bp | Asymptomatic |
| Medial approach | |||||||
| 7 | >1 | >1 | PDP | PDP | II | Bp pop-pop | Asymptomatic |
| Posterior approach | |||||||
| 7 | 0.50 | >1 | Fe+ R- | PDP | II | Pop-pop Bp | Asymptomatic |
| Posterior approach | |||||||
| 8 | 0.82 | - | Fe+ Pop- | NC | II | No surgery | Asymptomatic |
The eldest patient (patient n#2) underwent a posterior approach surgery for a secondary portion popliteal artery aneurysm (Fig. 8) and, as an intraoperative finding, PAES was diagnosed as a result of anomalous insertion of the medial fascicle of the gastrocnemius that was compressing both popliteal artery and veins.
Fig. 8
Entrapment related popliteal artery aneurysm RLL.
One of the patients was in her fourth month of pregnancy when she presented with acute ischemia. During the surgery, a fusiform dilatation and thrombosis of the popliteal artery was found (Fig. 9).
Fig. 9
Thrombosis of an ectasic popliteal artery.
Autologous veins were used in all cases to repair the arterial injuries (Fig. 10). In one case, a popliteal artery plasty with a vein patch was performed to preserve hyperplasic gastrocnemius arteries in a limb with poor run-off. Prosthetic material was never used.
Fig. 10
Autologous vein graft.
All patients, in addition to limb revascularization, underwent anatomical repair. The gastrocnemius was inserted into its correct position and postoperative rehabilitation therapy was initiated in type II PAES limbs. In type III and V PAES limbs the anomalous gastrocnemius muscular fascicle that was compressing the artery was freed. In cases of functional artery entrapment syndromes, the hypertrophic muscles that caused the vascular occlusion (soleus muscle and fascia, posterior fascia of the popliteal muscle and plantaris muscle) were released (Fig. 11).
Fig. 11
Classification of popliteal artery entrapment syndrome (PAES).
Results
The types of entrapment, presenting features and treatment are summarised in Table 1, Table 2.
The mean follow up period in those patients who underwent surgical treatment was 3.6 years (range: 1 to 8 years). Periodic postoperative follow-ups with Duplex and ankle/arm index Doppler explorations were carried out every one, three and six months after surgery.
There were seven cases with entrapment type II, one type III, one type V, and three symptomatic functional popliteal artery entrapment. Seven limbs presented with occlusion of the popliteal artery, one with infrapopliteal occlusion and four limbs had positive distal pulses with focal injury of the popliteal artery.
We made seven popliteal-popliteal reverse saphenous vein bypasses, one femoro-popliteal vein bypass and another one with popliteal-tibio peroneal trunk grafting. We preferably replaced the occluded popliteal artery with vein. In one patient (n° 4) we had to treat the symptomatic limb with an angioplasty and patching to preserve a large collateral in context of a poor run-off.
The n° 1 patient, was a male who presented an acute ischemia and after treatment with fybrinolitic drugs we discovered a bilateral focal injuries of the popliteal artery. An angio MRI showed bilateral functional PAES. Bilateral popliteo-popliteal bypasses using a medial approach were performed. After 5 years, one bypass occluded resulting in a 500m non disabling intermittent claudication.
One female patient (case n° 3) that presented with acute ischemia and poor distal run-off suffered an early occlusion of the femoro-popliteal bypass and needed graft trombectomy. The bypass occluded again, but three years after intervention the patient complains of non-disabling intermittent claudication.
The pregnant patient presented with a 70% stenosis of the popliteal artery and a fusiform aneurysm on a duplex scan. However, during surgery we found a trombosed artery. We resected the aneurysm with a reversed saphenous vein interposition graft, via a posterior approach of the popliteal artery. Currently the bypass is patent and the patient is asymptomatic. In the patient n° 2, the posterior approach was a personal choice of the surgeon, because of the location of the aneurysm in the second portion of the popliteal artery. Initially we suspected an atherosclerotic aneurysm. During surgery we found an anomalous muscular band of the gastrocnemious muscle that compressed both vein and artery. After the artery and vein were released, the aneurysm was resected and a short interposition bypass with reversed vein was performed. The patient remained healthy with distal pulses present and without oedema of the leg. An angio MRI after surgery was made and there was no contralateral PAES.
There were two bypass occlusions (one early and the other five years after surgery). There was no resulting limb loss. The remaining vascular bypass procedures continue to be patent and all patients remained healthy. Eight patients are asymptomatic, three have non disabling claudication and one only has claudication with strenuous exercise. Treatment with anti-platelet aggregation agents was indicated in all patients.
Discussion
PAES is an important cause of intermittent claudication in young health subjects without risk factors for arteriosclerosis. It is not easily diagnosed and its prevalence varies in the current literature. Gibson and colleagues11 reported an incidence of 5% in 86 necropsies while, in a review of 20,000 Greek soldiers, PAES was detected in 0.17% of cases.12
PAES implies a series of changes of the popliteal artery, as a consequence of extrinsic compression; dilatations, true aneurysms, arterial thrombosis (mainly at the third segment) and the presence of large nets of collateral vessels.13 Furthermore, in approximately 10–15% of cases, venous compression coexists with arterial entrapment (type V).9, 14
PAES should be suspected in all patients below 50 years of age, with a clinical history of intermittent claudication of the calves or the plantar areas, especially if they are sportsmen, and have isolated obstructive injury or an aneurysm of the popliteal artery.15 Therefore, diagnosis is primarily based on clinical history, physical examination, non-invasive tests and subsequent invasive test procedures.16 PAES is commonly seen among men, although not necessarily athletes, while functional entrapment affects mainly athletic women.17 In our cases, one was 63 year old, seven patients were between 24 and 43 years old, and none had associated vascular risk factors. We did not suspect PAES in the elderly patient.
Symptoms commonly begin suddenly, often after intensive exercise involving lower limbs. In some cases of arterial compression, without an occlusion, claudication presents as pain in the calves upon walking over short distances but not over long distances, or when running. Some patients also present with a true arterial aneurysm distal to the arterial compression site.18
Upon physical examination, the patient displays normal foot pulse at rest if the arterial occlusion has not yet occurred. The ankle/arm index is usually normal, although if extreme plantar or dorsal foot flexion movements are requested, the foot pulses may diminish and even disappear. A positive test result is considered if the provocative maneuvers provoke attenuation of the index to 0.5.15, 19 However, this examination is not useful in cases of pre-existing popliteal artery compression and may provide false positive results in cases of anatomical variants or dorsalis pedis artery hypoplasia. In our series the ankle/arm index was not useful to diagnose the PAES. Nine patients had less than 1, without changes with provocative maneuvers. In the cases with index >1 the maneuvers were not conclusive either.
Duplex ultrasonography exploration with provocation maneuvers is another screening technique for PAES. A decrease in peak systolic flow of the popliteal artery could be indicative of PAES.20 However, false positive results are also possible with this test, mainly among athletes,6, 21 as it does not discriminate between anatomical entrapment or functional flow impairment.17
Arteriography was the traditional gold standard exploration for the diagnosis of popliteal entrapment as it could identify the site of arterial injury, whether it was occlusive or aneurysmatic. However, nowadays, MRI scans are probably the best diagnostic exams as they allow for a thorough evaluation of anatomical relationships between the muscle and tendon, differentiation between anatomical and functional impairment mechanisms, and measurement of intrinsic vascular disease compared to extrinsic compressions.17, 22 MRA has been proven to be superior to duplex, mainly in cases that accompany arterial occlusion, and CT scans as it does not require contrast injection. Therefore MRA should be considered as a first-line screening test before the performance of arteriography and surgical repair.23
All anatomical entrapments of the popliteal artery should be surgically repaired whether it provokes symptoms or not. The natural evolution of this syndrome is progression of vascular disease until final vessel occlusion with a subsequent ischemic limb event.24 The exception, as decribed by Turnipseed and colleagues, could be asymptomatic functional entrapment, based on the fact that patients with this modality have higher risk of late arterial complications, therefore, the surgical repair should be reserved in those patients that develop clinical symptoms.17
The objective of the surgical repair is to keep the patient symptom free, to avoid arterial wall damage and to prevent peripheral embolisms.19 The decision to undertake a medial or posterior approach for the treatment of PAES should be based on detailed information supplied by complementary investigations. The medial approach should be routinely chosen in those cases where a functional popliteal entrapment is suspected or when a tibial trunk bypass is also required. If anatomical abnormalities or fibrous bands are not detected the soleus muscle's tibial insertion should be released. The thickened soleus muscle's anterior fascia should be released along with the popliteal muscle's posterior fascia. The tendon of the plantaris muscle should be incised and the proximal muscle portion should be removed from the surgical field.5
The posterior approach is appropriate if muscular and tendinous decompressions of the popliteal fossa, local popliteal artery repairs or short bypasses are required.17 This way, the existing anatomical abnormalities can be identified and repaired. The vascular approach is performed between the two heads of the gastrocnemius muscle, being careful to avoid nerve injuries during nerve retraction.25 Occasionally, muscle reinsertion, in its correct position may be made. Controversy exists about reconstruction of the transected muscle. Some authors say that recontruction is not necessary,26 Kudo et al., think that transected medial head of gastronemious muscle may reattach itself to an abnormal site and provoke compression again of the popliteal vessels. We believe that when resecting the medial head, surgical repair should be carried out to restore the muscle function and lessen rehabilitation time. On this base, we prefer repair the transected muscle in type II PAES.
The administration of thrombolytic agents in patients first presenting with symptoms of acute ischemia may help to provide a better definition of subjacent vascular injuries and could provide supplementary information for decision taking during surgery.27 We used fybrinolityc therapy in one case with acute ischemia and occluded superficial and popliteal artery. After this treatment, focal injury bilateral of the popliteal artery made suspect PAES.
Conclusion
PAES is often more prevalent than actually diagnosed and it should be considered in young patients with intermittent claudication without associated vascular disease risk factors or in those with atypical claudication without other evidence of arterial insufficiency. Contralateral examinations should be performed due to a high incidence of bilateral abnormalities. We consider MRA as the diagnostic tool of choice. PAES is a pathology of young people and due to the natural evolution of the arterial injury, in the entrapment should be corrected in both symptomatic and asymptomatic limbs, whereas treatment of functional entrapment should be reserved for symptomatic patients.
References
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- Diagnosis of popliteal artery entrapment syndrome: the role of duplex scanning. J Vasc Surg. 1991;13:434–438
- . Popliteal artery compresion and force of active plantar flexion in young healthy volunteers. J Vasc Surg. 1997;26:281–287
- . Non invasive vascular imaging in the diagnosis and treatment of adventitial cystic disease of the popliteal artery. J Vasc Surg. 1997;26:715–720
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- . The role of streptoquinase in treating complicated popliteal entrapment syndrome. J Vasc Surg. 1991;13:N°4
PII: S1533-3167(06)00066-5
doi:10.1016/j.ejvsextra.2006.05.003
© 2006 Elsevier Ltd. All rights reserved.
