Anatomical insights into the median septum on soleal vein network and deep vein thrombosis risk

The high incidence of deep vein thrombosis (DVT) in evacuees has been recognized since the 2004 Niigata-Chuetsu Earthquake in Japan. We hypothesized that the number and location of communicating branches of the soleal veins might influence thrombus development and that the median septum of the soleus muscle influences the venous network of the soleal veins. This study aimed to investigate how the network of soleal veins varies with the shape and thickness of the median septum and to elucidate factors predisposing soleal veins to DVT. The lower legs of 30 sides from 15 formalin-preserved cadavers were observed. The central soleal vein, the predilection site for thrombus among the six veins within the soleus muscle, divides into three branches: medial, central, and lateral. The soleus muscle has a unique architecture with converging muscle fibers on the anterior surface of the median septum. We examined the positional relationship between the central soleal vein and the median septum. The median septum morphology was either straight (14 sides, 46.7%) or curved (16 sides, 53.3%). The number of communicating branches was significantly higher in the curved type. The curved type also had a communicating vein penetrating the median septum, with the central branch passing deeper than in the straight type. The median septum could restrict the enlargement of communicating branches, causing thrombosis through disturbance of venous blood flow. Future research will clarify the median septum's influence on the soleal vein, potentially identifying soleus muscles at high risk of developing DVT.