Popliteal artery. It is an elastic artery by virtue of the movements of the knee joint (continuous flexion and extension). When changing its structure and losing elasticity, it does not support these movements and thrombuses.
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- 1 Popliteal hollow
- 1 Structure
- 2 Popliteal artery entrapment syndrome
- 1 Anatomical state
- 3 Etiology
- 4 Special circumstances that can cause ischemia
- 1 Primary thrombosis of the popliteal artery
- 2 Thrombosis of a popliteal aneurysm
- 3 Cystic degeneration of the popliteal artery
- 4 Popliteal artery entrapment syndrome
- 5 Sitology
- 6 Diagnosis
- 1 Differential diagnosis
- 7 Treatment
- 8 Sources
In human anatomy, the popliteal hollow is a more or less rhomboidal depression with a vertical major axis, located in the region of the animal legs, which can be seen at the back of the knee, especially when the leg is flexed or semi-flexed.
The popliteal hollow is limited by six walls, muscular and fascial mainly:
- External super wall: the biceps femoris muscle.
- Super-internal wall: the semi-membrane, semitendinosus, internal rectum and sartorius muscles.
- External infero wall: the external twin.
- Intra-internal wall: the internal twin.
- Anterior wall: the femur and the popliteal muscle .
- Posterior wall: the fascia of the popliteal region, and integuments.
From the outside in, the greater sciatic nerve is located at the level of the upper angle of the popliteal fossa, it bifurcates into its terminal branches: the internal popliteal sciatic nerve or tibial nerve and the external popliteal sciatic nerve or common peroneal nerve.
The Popliteal Vein occupies the median plane, between the artery and the nerve of the region. At the level of the joint line, it receives the external saphenous vein; The latter runs along the floor of the popliteal fossa, and before emptying into the popliteal vein it crosses to the inner side of the internal popliteal sciatic nerve.
In the deepest plane is the Popliteal Artery (it should be noted that it becomes a popliteal artery when it crosses the ring of the third adductor or femoral hiatus , highlighting that previously, the name of femoral artery corresponded to it), supported on the skeleton, it descends obliquely outwards, until it reaches the soleus ring, here it ends up dividing, in the tibiofibular trunk and in the anterior tibial artery . The popliteal hole corresponds to the hamstring, in common language.
Popliteal artery entrapment syndrome
The popliteal artery is the continuation of the femoral artery. It owes its name to the deep location it occupies on the posterior aspect of the knee joint, at the bottom of the popliteal socket. It is the trunk of origin of the nutritional arteries of the leg and foot.
The popliteal artery begins at the inner edge of the femur, in the ring of the third adductor, about 8 cm above the knee joint line. It ends in the soleus ring, where it forks into its two terminal branches, the anterior tibial artery and the tibiofibular trunk. Its average length varies between 17 and 18 cm.
On its way, when leaving the Hunter’s duct, the artery descends through its upper part or first portion, obliquely, outwards. Then it tilts and becomes vertical, descending along the axis of the popliteal rhombus. This is its second portion, which is not axial, but is located somewhat inside the midline.
From the tibial plateau it is called the third portion and follows the same path as its anterior segment. These three divisions of the popliteal artery are practical from a surgical point of view in vascular surgery. It is closely related to the popliteal vein and the internal popliteal sciatic nerve. The popliteal is one of the body’s most movable arteries (the extension and flexion of the knee forces the artery to kink frequently).
When the lesions are of the atherosclerotic type, they are due to conditions that also affect the superficial femoral artery, hence the previous article we called it “Femoropopliteal Obliteration”. Typically, in these cases, Hunter duct occlusion occurs with distal progression. Popliteal arteriosclerosis, in its most distal form, is usually more severe because the collateral circulation in this area is less likely to develop.
Special circumstances that may cause ischemia
Primary thrombosis of the popliteal artery
In certain circumstances, the popliteal artery loses its mobility and reacts to repeated trauma (its own pulsatility) with occlusion. This primary thrombosis of the popliteal artery was described by Boyd and closely resembles Hunter’s duct artery disease described with Palma.
Clinically it occurs in young people, under 35 years of age. The most striking, and nothing short of exclusive, symptom is intermittent calf claudication. The disease is always local. There are never general signs of thromboangiitis or arteriosclerosis. The pathological anatomy shows absence of inflammatory or degenerative alterations in the arterial wall.
The clinical suspicion can be confirmed by Doppler and arteriography by ipsilateral percutaneous femoral puncture reveals a short segmental occlusion of the popliteal in its second / third portion. Resection of the obliterated sector and vein graft is the most recommended therapy.
Thrombosis of a popliteal aneurysm
The popliteal artery is, in order of frequency, the second place, after the aorta, where arteriosclerotic aneurysms are located. Very often they are bilateral (50%). They have a predilection for males and they generally occur in people who have exceeded 50 years of age.
If not treated surgically, popliteal aneurysms show serious complications: embolism, thrombosis, ruptures, etc. The tendency to embolism and / or thrombosis is due to the presence within the aneurysmal sac of mud, made up of old clots that completely fill the cavity, in such a way that a popliteal artery that does not appear dilated is frequently seen on arteriography.
There is, therefore, a discordance between computed tomography (CT) or magnetic resonance imaging (MRI) and arteriography. This thrombosing tendency of the popliteal aneurysm is greater than that of other aneurysms, which results in ischemia, which can be severe due to the shortage of collaterals in this arterial pathway (Fig. 1).
The symptoms are characterized by the presence of a pulsatile lump that the patient himself usually discovers casually. Given the deep location in a bony hollow of the popliteal artery, these aneurysms remain asymptomatic for a long time.
Its diagnosis is easy when palpating a tumor that is slightly displaceable in the transverse direction, pulsating and expanding, and which can be partially reduced. Doppler ultrasound, CT, and / or MRI confirm the diagnosis .
Arteriography considerably facilitates the practice of surgical intervention for resection and interposition of a saphenous vein graft or PTFE.
Spontaneous intraaneurysmal thrombosis is a complication that can lead to the healing of these aneurysms, with the disappearance of compression discomfort, or can lead to an ischemic condition, which can be acute with serious repercussions for the limb, or chronic, with clinical symptoms of intermittent claudication of the twin mass.
It is possible in some patients that the formation of the aneurysm and its spontaneous thrombosis go unnoticed, accidentally discovering the tumor when exploring the patient, in which case, the differential diagnosis will be made with the other possible tumors of the knee: sarcomas, hemarthrosis, cyst from Becker etc.
Cystic degeneration of the popliteal artery
Hiertong, Lindberg and Rob described, in 1957 , 4 cases of segmental obliteration of the popliteal artery due to cystic degeneration of the adventitia. All the patients were young, with no previous history of trauma, with a sudden onset of intermittent calf claudication. They had no symptoms or signs of general vascular disease (arteriosclerosis, thromboangiitis).
The etiology is unknown, although degeneration is assumed to occur by the same mechanism as the primary thrombosis described by Boyd. The lesion is located in the second portion of the popliteal, which is located above and below the obliteration of normal caliber and characteristics (first and third portions).
The mucous degeneration is located outside the middle tunic and inside the adventitia, leaving the arterial lumen occluded by the gelatinous mass under high tension. The walls of the cyst are covered by flat cells. Treatment is surgical and consists of the removal of the affected arterial segment and interposition of a venous graft or PTFE (Figures 2a and b).
Popliteal artery entrapment syndrome
Popliteal artery entrapment syndrome is due to external compression of the popliteal artery, caused by the congenital abnormality in the development of the circulation of the popliteal fossa and / or the musculature, preferably of the internal gastroknemic muscle.
It was an Edinburgh medical student , Stuart, who first described in 1879 the anatomical abnormality of the popliteal artery in relation to the internal twin muscle by dissecting the amputated lower limb to a 64-year-old patient.
In 1959 , the Dutch Hamming made a definition of the picture and made the first surgical correction. In 1965 , Love and Whelan coined the term “popliteal artery entrapment syndrome” which is subsequently accepted worldwide.
There are various theories that can explain this anomaly. Vascular theory emphasizes the absence of development of the circulation of the popliteal fossa, maintaining the fetal situation posterior to the internal twin muscle. The muscular theory described by Carter and Eban shows the persistence of the peroneal insertion of the internal twin muscle, in an abnormal position, migrating to the supracondylar area of the femur. The mixture of both could explain the multiple possibilities that are observed in the type of compression of the popliteal artery.
Its incidence in the context of possible popliteal artery injuries is around 1%. However, a higher frequency is accepted, because the lesion can go unnoticed when the popliteal artery is occluded, which is why it is wrongly classified as arteriosclerotic disease in certain cases.
On the other hand, because it usually occurs in young people with mildly disabling symptoms, in some cases a correct diagnosis is not made. In fact, in general, these are men under the age of 30, a large number of athletes and in whom between 25 and 30% of cases the condition is bilateral.
Its characteristic symptomatology is intermittent twin claudication. Due to the suspicion of the lesion by clinical examination, a Doppler study should be carried out, which generally confirms a segmental occlusion of the popliteal artery. If the hemodynamic examination is normal, dorsiflexion tests of the foot with knee extension will be carried out, which will demonstrate the disease, with loss of the Doppler speed wave.
Likewise, the CT, MRI and / or arteriography technique can be used for homolateral percutaneous puncture, if possible the latter, with dorsiflexion of the foot, which is the position that will show an occlusion in the second / third portion of the popliteal artery.
In 1971 Delany and González made a classification into four types (figs. 3 ad).
- The popliteal artery is located medial and posterior to the tendon of the internal twin, which occupies a normal position.
- The internal twin insertion is more lateral than normal and the popliteal artery passes underneath it.
III. An accessory bundle of the internal twin comes from the femur, more lateral than the main tendon, which is in a normal position. The popliteal artery is compressed by this accessory bundle.
- The popliteal artery is usually in its normal position, but it is compressed by a deep popliteal muscle inserted higher than normal or by a fibrous band.
The proposed therapy is surgical, and consists of arterial release when it is patent, if the artery is obliterated, the possibility of grafting with a saphenous vein or PTFE should be evaluated.
Complete segmental occlusion of the popliteal artery manifests with intermittent calf claudication. In general, if it is a primary thrombosis, cystic degeneration, or popliteal artery entrapment syndrome, obliterations tend to park, against arteriosclerotic or arteritic-type lesions.
In the case of thrombosis of a popliteal aneurysm, the symptoms may be more extensive, since by compression of structures that accompany the artery (neuralgia, popliteal-distal venous thrombosis), either the clinic of an ischemic picture due to embolization / thrombosis of the distal arterial axis (tibiofibular trunks), favored by emigration or mobilization of the thrombus that occupies the aneurysmal cavity.
The segmental obliteration of the popliteal produces an intermittent claudication clinic in the calf, identical to that of the femoropopliteal occlusion, for which reason the same differential diagnosis must be considered here with all the pains that affect the leg.
In the case of thrombosed popliteal artery aneurysm, since there may be swelling of the knee or compression of the satellite structures, it is necessary to differentiate these pains that are located in the knee area.
In case of chronic non-disabling Grade II ischemia, medical treatment may be followed. In cases III or IV, a saphenous vein or PTFE graft should be performed.