Variability of the deep femoral venous system

Summary

Deep venous system is known for its extreme variability but still in anatomy it is on the border of interest. Although a few previous anatomical studies have already pointed out the fact of a significant discrepancy between the autopsy findings and the literary description, it has not had any particular output so far. Our findings confirmed the deep femoral vein (DFV) to be an alternative collateral vein connecting the popliteal vein (PV) with the femoral vein (FV).

Key words:
deep veins, deep femoral vein, collaterals, varieties

Introduction:

Deep veins of the thigh run in the lower limb between the skeletal muscles, covered with fascia. The femoral vein passes alongside the same named artery from the adductor canal up to the inguinal ligament. Both vessels are found in the vascular lacuna, the vein is medial to the artery here. In the anatomical textbooks the description of the femoral vein and its tributaries is usually very sketchy and commonly only the great saphenous and the deep femoral veins are mentioned. Among the alternative tributaries of the deep femoral vein the medial and lateral femoral circumflex veins are named. The vein is constituted by fusion of the venae comitantes of the perforating arteries (1, 2, 3).

For clinical purposes the anatomical nomenclature of DFV has been up-dated and the following segments are newly distinguished (4):

• vena femoralis communis (common femoral vein), a short segment of the vena femoralis between its confluence with the vena profunda femoris and the inguinal ligament, and
• vena femoralis (femoral vein), which originates from the popliteal vein and stretches between the hiatus adductorius and the confluence with the vena profunda femoris.

The often used term “vena femoralis superficialis” for the deep femoral vein has not ever been a part of any nomenclature and it is found to be confusing from the topografical point of view (4, 5, 6).

The superficial and the deep limb veins form a functional unit. Both of the systems are interconnected by perforators, valves regulate the blood flow centripetally. Deep veins drain 90 % of the limb blood.

Venous perforators (transfascial connections between the superficial and deep veins) are in the thigh less frequent than in the leg and are very variable. They may form even a subfascial venous system. In the femoral region they mostly arise from the great saphenous vein tributaries, most of the perforators possess valves. In the thigh the following perforators are distinguished (6, 7):

• medial: anteromedial (connect the great saphenous vein with FV) and inguinal
• anterior (piercing the quadriceps femoris muscle)
• posterior: posteromedial (through adductors) and posterolateral (through the biceps femoris muscle)
• lateral

Ultrastructure of the venous wall and valves displays a great variability. Wall stratification is similar to arteries, boundaries between the layers are less distinct. Tunica intima is formed by endothelium and subendothelium: longitudinally oriented elastic fibres may in the lower limb veins cumulate in the internal elastic lamina. Tunica media is thinner in veins comparing with the same sized arteries. Collagen and sparse elastic fibres are found here. There are even smooth muscle cells arranged into spiral bundles in the propulsive veins. Tunica adventitia is the most prominent layer in veins. It is formed by large amounts of collagen and longitudinally oriented bundles of elastin and smooth muscle cells.

Valves are a fundamental venous structure. They are found in all veins distally to the external iliac vein. Valves develop as a duplication of all layers of intima, formed usually by 2 – 3 cusps. To prevent regurgitation they are situated under the opening of a tributary. The more distally in bloodstream, the more valves there are. FV holds 2 – 3 valves, the great saphenous vein 14 – 18 (small saphenous vein 20), whereas 2 valves at minimum are present in the saphenofemoral or the saphenopopliteal junction.

The width of lumen and the course of veins show a considerable variability that may be caused also by the developmental abnormalities (malformations). The early developmental stage of veins in human according to Dvorak (8) shows Fig. 1.

From a finlike base of the lower limb the blood is drained by the marginal veins – v. marginalis tibialis et fibularis. The tibial marginal vein perishes, while from the fibular one develops the main stem that opens into the v. cardinalis posterior, later into the v. hypogastrica. The distal segment of v. marginalis fibularis runs from the knee superficially and forms the great saphenous vein, while the proximal segment is found in the depth under the thigh flexors and targets as the v. ischiadica accompanying the infrapiriform foramen. The great saphenous and femoral vein develop then, the latter connects proximally with the v. ischiadica. It eventually perishes and the main blood vessels evolve in the thigh anteriorly. V. glutea inferior remains from the former v. ischiadica and may become a variable collateral vein called v. femoralis dorsalis (9).

The following venous anomalies and malformations are distinguished:

• agenesis – congenital absence of the entire vein or its segment
• aplasia – defective development causing below normal size of vein
• hypoplasia – is similar to aplasia, but less severe
• dysplasia – complex abnormality of development (of size, structure or course)
• venous aneurysm
• venous „doubling“ – complete or incomplete – causes usually FV or PV
• persisting embryonic veins – v. ischiadica most frequently

Case Report

The variability of FV has been proved also by our own autopsy findings. In the last autumn during the routine dissection we found in both limbs of an 80-years-old man an atypical vein, that attained a diameter of 1 cm and run as a FV collateral (Fig. 2, 3). This non-doubled vein, 0.95 cm in diameter, arised from the popliteal vein. It received many muscular tributaries in the femoral region, its diameter 10 cm below the sciatic tuberosity was 1.2 cm (diameter of the femoral artery at the corresponding level was 0.9 cm). The vein drained laterally into the femoral vein 13 cm below the inguinal ligament. The diameter at the site of its orifice was 1.2 cm. Valves were centripetally oriented, histological examination showed an average venous wall structure.

Subsequent autopsies of the distal femoral region of 4 women and 2 men (age 73 – 88) proved the presence of a similar finding in 3 out 11 dissected extremities, concretely in one man bilaterally, in a woman unilaterally (the second limb was used for other purposes and thus could not be dissected).

Discussion

In spite of the deep venous thrombosis importance very little attention is paid to the deep lower limb vein variability in the current anatomical and clinical textbooks. Several previous anatomical studies have already pointed out the distinctive discrepancy between the autopsy findings and the literary description (10, 11). Study by Mavor et al. is in the description of the connection between DFV and veins in the popliteal fossa the most detailed. In 22 dissected lower limbs DFV had a direct communication with PV in 38 %, in 48 % via indirect tributaries of the latter. Thus in 86 % the DFV was found to be a potential collateral of the lower femoropopliteal segment. The vena femoropoplitea, which is in some texts (3, 4, 12) described as a variable vein on the dorsal aspect of thigh opening into the small saphenous vein, is not in the most foreign textbooks mentioned and could not be proved by our autopsy findings either. Therefore it is suggested that the femoropopliteal vein is likely to be a variable deep femoral vein as well.

Conclusion

The variable deep femoral vein, a large vein connected with the popliteal vein, may serve as an important collateral in case of the femoral vein occlusion, e. g. in traumatic thrombosis in the adductor canal. Knowledge of this variety might be found useful also for the interpretation of some imaging methods.

Corresponding adress:
Lada Eberlova, M.D.
Charles University in Prague, Faculty of Medicine in Pilsen
Department of Anatomy
Karlovarská 48, 301 00 Plzeň
E-mail: lada.eberlova@lfp.cuni.cz
tel. 00420 377 593 300