A lateral abdominal wall mass with fixed pressure pain is the main clinical sign of a hallux valgus hernia. We all want to know how it is caused? The semilunar line is located at the outer edge of the rectus abdominis sheath, an arc extending between the ninth rib and the pubic symphysis, which is the location where the tendon membrane of the internal oblique muscle splits into two layers and is incorporated into the anterior and posterior sheaths of the rectus abdominis muscle, respectively. An external ventral hernia formed by a defect in the semilunar line is known as a semilunar hernia. Meniscal hernias are uncommon in clinical practice and are characterized by the presence of a reducible swelling at the meniscus and a localized defect at the meniscus. Congenital hallux valgus hernias are relatively rare and most are acquired. The semilunar tendon membrane is one of the congenital weak areas of the anterior abdominal wall, and the semilunar tendon membrane structure is generally considered to be most closely associated with the development of semilunar hernias. Other predisposing factors are similar to other extra-abdominal hernias (including increased intra-abdominal pressure and disorders of collagen metabolism). In humans, intra-abdominal pressure is greatest in the lower abdomen when walking upright, while the posterior sheath terminates in the mid-lower abdominal position, and thus a hemilineal hernia most often occurs in this region. Advanced age and weight loss are generally considered important causative factors for semilunar hernias. Paralysis of the abdominal wall muscles is also a possible pathogenetic factor.