Popliteal vessels entrapment syndrome

　　The exact etiology of popliteal vascular entrapment syndrome is not yet clear, but the anatomical variations between the muscles and blood vessels in the popliteal fossa of the lower limb are closely related to embryonic development.

　　1. Embryological BasisThe lower limb arterial system originates from two embryonic arteries, namely the axis artery and the external iliac artery, both of which come from the umbilical artery, which is a branch of the dorsal aspect of the aorta. Among these two embryonic arteries, the most basic and important is the axis artery, which forms at 30 days of embryonic development. The other is the external iliac artery, which appears at 32 days of embryonic development and emits the femoral artery around 38 days. The axis artery runs longitudinally along the posterior aspect of the lower limb, while the femoral artery runs anteriorly. At 42 days of embryonic development, the axis artery can be found beneath the developing popliteus muscle at the knee joint. At this stage, according to its anatomical relationship with the popliteus muscle, the axis artery is divided into three segments: the proximal popliteal segment, the deep popliteal segment, and the distal popliteal segment, and are named the ischiadic artery, deep popliteal artery, and interosseous artery, respectively. At this stage, superficial communicating branches also form, entering the popliteal fossa through the adductor canal foramen to connect the femoral artery and the ischiadic artery. At 48 days of embryonic development, the ischiadic artery emits a branch near the superior margin of the proximal popliteus muscle, runs on the superficial aspect of the popliteus muscle, and is named the superficial popliteal artery. It connects with the interosseous artery at the distal end, which later develops into the posterior tibial and peroneal arteries. Over time, the deep popliteal artery atresia. In normal individuals, the popliteal artery is formed from the fusion of the superficial communicating branch, ischiadic artery, superficial popliteal artery, and interosseous artery from proximal to distal. At the same time as the development of the femoral-popliteal vessels, the adjacent gastrocnemius muscle also begins to develop. Initially, the medial and lateral insertions of the gastrocnemius muscle are located at the femoral epiphysis, and as the infant transitions from crawling to walking, the insertion points rise along the epiphysis to the diaphyseal epiphysis of the femur, and the insertion point of the medial head is higher than that of the lateral head. In normal adults, the medial head of the gastrocnemius muscle is located at the caudal aspect of the adductor canal foramen, and the popliteal artery runs on its lateral side. Any change at any stage of development will inevitably affect the normal anatomical relationship between the medial head of the gastrocnemius muscle and the popliteal artery.

　　2. EtiologyDue to the fact that the popliteal artery can be located deep in the popliteus muscle, from an embryological perspective, the persistence of the deep popliteal artery can lead to popliteal artery entrapment syndrome. Overly extensive migration of the medial head of the gastrocnemius muscle along the femur towards the head can also cause the disease, where the popliteal artery can be found on the medial side of the gastrocnemius muscle or passing through the medial head. The most common condition is the popliteal artery wrapping around the medial head from the inside and entering the popliteal fossa, then extending to the outside, running beneath the medial head, and located between the medial head and the medial condyle of the femur. Other muscles, fascicles, and fibrous bands in the popliteal fossa can also participate in this complex change, and sometimes even involve tissues such as veins and nerves. Another functional popliteal artery entrapment syndrome may be related to vascular compression caused by hypertrophy of the gastrocnemius, popliteus, plantaris, or semimembranosus muscles, and is often found in athletes.

　　Complications such as graft thrombosis, hemorrhage, infection, and deep vein thrombosis of the lower extremities may occur after surgery. The disappearance of the dorsalis pedis pulse suggests graft thrombosis. Arteriography can make a definitive diagnosis, and reoperation should be considered. Postoperative hemorrhage is rare, but if it occurs, it should be removed under sterile conditions in the operating room, and the wound should be completely stopped. When deep vein thrombosis of the lower extremities occurs, anticoagulant thrombolytic therapy should be performed.

　　The main symptoms of popliteal vascular entrapment syndrome are as follows:

　　1, Intermittent claudication: Most patients start with intermittent claudication, but the way of onset of claudication is not completely consistent. Initially, symptoms such as numbness, weakness, and spasm-like pain in the calf may occur during fast walking or running, and the symptoms disappear after stopping. However, there are no symptoms during slow walking. This may be related to the pressure on the gastrocnemius muscle during contraction. Conversely, a few patients may not have symptoms during rapid walking, but may have intermittent claudication during slow walking. These patients do not show ischemic symptoms at rest. Once the artery is blocked, ischemic intermittent claudication and other ischemic manifestations will appear.

　　2, Limb ischemia : According to statistics, about 1/3 of patients have an acute onset, but the course of most patients can last for several months or years, or even longer. After the arterial obstruction, the affected limb will appear symptoms such as cold intolerance, pale skin color, and muscle atrophy, which are typical signs of ischemia. When the patient is in a certain special posture, symptoms such as numbness or pale skin in the affected limb may occur, and these symptoms can disappear after changing the posture. However, the ischemic symptoms of most patients are not severe. About 10% of patients have acute and severe ischemic symptoms, but it is relatively rare to cause extremity ulcers, gangrene, and severe static pain.

　　3, Bilateral deformity: Lesions involving both lower limbs account for about 30%, but are all related to the extent of vascular involvement. With the continuous improvement of diagnostic technology, some patients with bilateral lower limb lesions may not have obvious clinical manifestations, but about 67% of patients with bilateral lesions can be diagnosed definitively through examination. In the treatment of 5 cases by Wang Jiaju, 1 case had bilateral lesions, with one artery occluded and one without obvious ischemic symptoms. This was found after arteriography. If the veins are also compressed at the same time, edema of the foot and lower leg may occur.

　　There is currently no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease. The patient's diet should be light and easy to digest, with an emphasis on eating more vegetables and fruits, and a reasonable diet. Pay attention to sufficient nutrition. In addition, patients should also pay attention to avoiding spicy, greasy, and cold foods.

　　The laboratory items for popliteal vascular entrapment syndrome mainly include:
　　One, Ankle pulse volume recording quantitative detection (PPG): During the stress test, a decrease in the pulse volume recording amplitude is evidence of arterial entrapment.
　　Two, Color Doppler ultrasound: Examination can be the preferred detection method for this disease, especially the dynamic measurement of the ankle arterial blood flow waveform, which is of great significance for diagnosis.
　　1. Doppler Pressure Measurement of the Ankle Artery: When the affected limb is in an overextended or flexed knee and the ankle joint is plantar flexed, the Doppler ultrasound detects a significant change in the pulse waveform of the foot back artery, which is a reliable diagnostic basis.
　　2. Doppler Flow Imaging of the Foot Back Artery in the Affected Limb: The Doppler flow imaging of the foot back artery in the affected limb can detect significant changes in the waveform and changes in the blood flow of the popliteal artery, which is of great significance for diagnosis.
　　3. Angiography: Arteriography is very important for the diagnosis of this syndrome. The stress test is performed simultaneously with the angiography, which can detect arterial entrapment that cannot be expressed at the ankle neutral position, with the most typical imaging manifestation being the internal displacement of the popliteal artery. If the popliteal artery is completely occluded, the popliteal artery will not be visible on the angiogram, and there will be collateral open around it. The segmental occlusion of the middle segment of the popliteal artery is easily confused with the external adventitial cystic degeneration of the popliteal artery, but the latter has a more extensive range of lesions, while the former is limited to the middle segment of the popliteal artery. Before the formation of arterial thrombosis, the external adventitial cystic degeneration of the popliteal artery is manifested as smooth filling defects in the lumen of the artery in angiography.
　　In addition, spiral CT and magnetic resonance imaging can not only confirm and supplement the results of arteriography but also reveal the anatomical relationship between abnormal muscles, fibrous bands, and blood vessels. This is of great significance for guiding surgery and discovering asymptomatic patients with this syndrome. It is generally believed that magnetic resonance tomography is superior to Doppler ultrasound and CT in diagnosing this syndrome.

　　In terms of diet, patients with popliteal vascular entrapment syndrome should pay attention to the following aspects:
　　1. The diet should be high in protein, rich in vitamins, calcium, and zinc. It is appropriate to eat more lean meat, eggs, fish, shrimp, animal liver, ribs, mushrooms, tofu, and cauliflower.
　　2. It is recommended to eat more foods such as spinach, chives, pumpkin, scallion, cauliflower, bell pepper, tomato, carrot, green vegetables, soybeans, walnuts, peanuts, pistachios, cashews, pine nuts, and almonds, as well as unpolished rice and pork liver soup, and so on.
　　3. Eat less or avoid spicy, salty, cold, and other difficult-to-digest and irritant foods.
　　4. In daily life, it is necessary to quit smoking, drink light tea, and drink alcohol moderately, without excess.

　　Regardless of whether the popliteal artery is occluded or not, all patients with confirmed popliteal vascular entrapment syndrome should undergo surgical treatment. The surgical treatment of this syndrome often depends on the severity of the symptoms and the extent of the lesion, and the surgical principle is to relieve vascular compression, reconstruct the blood vessels, and restore normal blood flow.
　　1. Surgical Treatment
　　1. Surgical Approach: Most scholars advocate the use of the popliteal posterior approach incision, which can fully expose the vessels and abnormal muscles in the popliteal fossa, and is therefore most commonly used. However, its disadvantage is poor exposure of the great saphenous vein and inconvenience in material collection. In a few cases, such as in type I patients, an medial approach incision (Szilagyi incision) can be used, which provides good surgical exposure for the lower segment of the popliteal artery, convenient material collection of the great saphenous vein, and facilitates the performance of femoral-popliteal bypass surgery. The disadvantage is that the tissue structure of the popliteal fossa cannot be fully exposed, and there is a possibility of missing the muscles, fibrous bands that compress the popliteal vessels, and so on, leading to recurrence after surgery, so it is not suitable for type II, III, and IV patients. When the occlusion of the artery involves the branches of the popliteal artery, the medial approach incision is more reasonable.
　　2. Surgical Method: Use epidural anesthesia or general anesthesia, the patient lies on his stomach with the lower limbs slightly flexed 10° to 15°. The incision is in the shape of an 'S', that is, the longitudinal incision is made on the posterior medial aspect of the thigh and the posterior lateral aspect of the calf, and the transverse incision is made 2 fingers above the popliteal crease. The skin flaps are flipped inward and downward, respectively, to expose the deep fascia. The deep fascia is incised longitudinally to avoid injury to the cutaneous nerves, and the small saphenous vein can be ligated to facilitate surgical exposure. Pay attention to protect the tibial nerve in the deep tissue, which runs along with the blood vessels in the vascular sheath. If the popliteal vein is not compressed, it can be seen running between the medial and lateral heads of the gastrocnemius muscle in the popliteal fossa. If the popliteal artery is not in the normal anatomical position, it can be dissected downwards from a higher position such as the outlet of the adductor canal in the popliteal fossa along the course of the popliteal artery, and an abnormal course of the popliteal artery can be found, located inside the medial head of the gastrocnemius muscle, behind the muscle and the femur, and between the knee joint. The popliteal artery is severely compressed between the knee joint, and the muscle or fibrous band compressing the popliteal artery at the starting point of the compression should be incised. The surgical incision must be complete, and attention must be paid to ensure that the entire popliteal artery can move after relaxation to avoid recurrence after surgery. If the popliteal artery is only compressed but not occluded, and the arterial wall has not yet appeared secondary fibrous hyperplasia, the popliteal artery can be released. Excision of the medial head of the gastrocnemius muscle will not affect the function of the lower limb, and if necessary, the cut medial head can be attached to the femur, located on the inside of the popliteal artery at the normal position after relaxation. For functional popliteal vascular compression syndrome (type VI), an incision of the medial head of the gastrocnemius muscle through the medial incision can completely relieve the symptoms.
　　3. Surgical Efficacy: The surgical effect is generally good. The most effective treatment method in arterial reconstruction surgery is venous graft bypass.
　　II. Anticoagulation Therapy
　　If the distal artery cannot be used due to unsatisfactory outflow due to extensive thrombosis after arterial occlusion, vascular bypass surgery cannot be performed. PGE1, refined rattlesnake anticoagulant enzyme, traditional Chinese medicine for promoting blood circulation and removing blood stasis, and other blood circulation and anticoagulant drugs can improve the blood circulation of the limbs.