What Is Posterior Hip Dislocation?

A posterior hip dislocation occurs when the femur bone slips backward out of its socket in the pelvis. Most hip dislocations are caused by motor vehicle accidents, serious falls and sport accidents from such high-impact activities such as football, acrobatics and snowboarding. Other causes are congential defects occurring more frequently in females than males, and complications stemming from posterior total hip replacement surgery. A hip dislocation is a serious medical emergency and requires immediate medical attention. The injury causes great pain, and delay or neglect of treatment may cause permanent paralysis or death.

The top of the femur, or thigh bone, has a ball-shaped protrusion called the femoral head, which is held firmly in place with ligaments and tendons. This ball nestles inside the concave socket of the pelvis, called the acetabulum. Such a joint is called a ball and socket joint and is usually very strong and allows the joint exceptional freedom of movement. Severe trauma can rupture the tendons and knock the femur from its position, tearing blood vessels and damaging nerves. Nearly all cases of hip dislocation are posterior, in which the femur slips toward the back of the pelvis.

The first step for posterior hip treatment is immediate intervention to prevent bone death and nerve damage. Physicians use a classification system called the Thompson-Epstein system for determining the extent of posterior hip dislocation injury and treatment. A dislocation with no obvious fracture can often be manipulated into position. Treatment gets more complicated when there is a dislocation with a fracture, usually requiring anesthesia and surgery. Recovery after posterior hip dislocation can take several months in which the patient is on bed rest and traction for the first few weeks.

Complications can arise from posterior hip dislocation even after proper hip function is restored. Bone death can occur as the result of blood supply cutting off during the trauma. Torn cartilage or bone fracture may develop into arthritis. Nerves damaged from the trauma may reduce sensation in the leg or foot. Immediate medical attention after the trauma helps to reduce long-term complications and disorders.

Additionally, patients who have had a middle hip replacement tend to suffer more frequent and spontaneous dislocations and must exercise caution to prevent injury. Crossing the legs or sitting low may cause the artificial femoral head to loosen and pop from the acetabulum. Anterior hip dislocation, in which the femoral head slips toward the front of the pelvis, is more common in people who have had middle or lateral hip replacement surgery.