Femoral hernia is not as common as inguinal hernia. It is often associated with incarceration or strangulation, resulting in peritonitis and mortality.
The pelvicrural interval (the opening from the abdomen to the thigh) is divided into two spaces: a lateral space, the lacuna musculosa, through which the iliopsoas muscles pass; and a medial space, the lacuna vasculosa, for the femoral vessels. The external iliac vessels run along the anterior surface of the iliopsoas muscle in the pelvis, pass between the iliopubic tract and Cooper’s ligament, and finally course beneath the inguinal ligament to become the femoral vessels. Where the external iliac vessels run down into the lacuna vasculosa, transversalis fascia covers the vessels to form the femoral sheath. It extends approximately 4 cm caudally and ends as the adventitia of the femoral vessels. The medial compartment of the femoral sheath is called the femoral canal, which is ordinarily less than 2 cm in diameter and contains lymphatic vessels and glands. The true opening of the femoral canal is a musculoaponeurotic ring, consisting of Cooper’s ligament inferiorly, the femoral vein laterally, and iliopubic tract superiorly and medially. In the past, the medial border of the femoral ring was for the lacunar ligament. The lacunar ligament is an attachment of the inguinal ligament to the pubic bone, however, and lies in the outer layer of the transversalis fascia.
McVay demonstrated that the medial boundary of the femoral ring is the lateral edge of the aponeurosis of the insertion of the transversus abdominis muscle with transversalis fascia onto the pectin of the pubis, not the lacunar ligament. Condon also demonstrated that the iliopubic tract bridges the femoral canal and then curves posteriorly and inferiorly, its fibers spreading fanwise to insert adjacent to Cooper’s ligament into a broad area of the superior ramus of the pubis. Thus, the true inner ring of the femoral canal is bounded by the iliopubic tract anteriorly and medially, and by Cooper’s ligament posteriorly. If a surgeon incises the inguinal ligament in a tightly incarcerated femoral hernia, he or she will find that the hernia cannot be reduced because of the more deeply placed ring. The distal orifice has a rigid boundary—surrounded by the lacunar ligament medially; the inguinal ligament superiorly; and the fascia of the pectineal muscle—and is usually less than 1 cm in diameter. The rigidity of these structures is the reason why strangulation often occurs in femoral hernias.
Currently, the ‘‘acquired’’ theory is widely accepted; however, the true cause of femoral hernia is not known. McVay demonstrated that the width of the femoral ring, which is determined by the length of the fanwise insertion of the iliopubic tract to Cooper’ ligament, is the main etiologic factor of the femoral hernia. Considering that the femoral hernia is very rare in children and most common in elderly women, however, McVay’s concept cannot be the only reason for the occurrence of femoral hernia. Nyhus noted the presence of a relatively large femoral defect without an accompanying femoral hernia during the preperitoneal approach. This may be caused by the acquired weakness of the transversalis fascia and a consequent predisposition to the development of the femoral hernia.
The ratio of femoral hernia relative to all groin hernias is reported to be 2% to 8% in adults . Femoral hernias are very rare in children, and most commonly observed between the ages of 40 and 70. The peak distribution is in the 50s, with a slight decrease in the 60s and 70s. As for sex distribution, femoral hernia is 4 to 5 times more common in female than in male; however, there are some reports that it is more common in men than in women. A right-sided presentation is more common than left, but the reason is not known.
Finally, femoral hernia is usually thought of as requiring emergency surgical treatment. Only 30% of our cases were treated as emergency operations, however, whereas 70% were elective. Unless patients complain of severe abdominal pain or ileus, surgeons need not perform emergency operations. In summary, the mesh plug hernia repair for femoral hernia has resulted in a reduced recurrence rate, shortened hospital stay, and a low rate of postoperative complications.