Hip Dislocation
A traumatic hip dislocation occurs when the head of the thighbone (femur) is forced out of its socket in the hip bone (pelvis). It typically takes a major force to dislocate the hip. Car collisions and falls from significant heights are common causes and, as a result, other injuries like broken bones often occur with the dislocation.
A hip dislocation is a serious medical emergency. Immediate treatment is necessary.
The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone).
A smooth tissue called articular cartilage covers the surface of the ball and the socket. It creates a low friction surface that helps the bones glide easily across each other.
The acetabulum is ringed by strong fibrocartilage called the labrum. The labrum forms a gasket around the socket, creating a tight seal and helping to provide stability to the joint.
When there is a hip dislocation, the femoral head is pushed either backward out of the socket, or forward.
- Posterior dislocation. In approximately 90% of hip dislocation patients, the thighbone is pushed out of the socket in a backwards direction. This is called a posterior dislocation. A posterior dislocation leaves the lower leg in a fixed position, with the knee and foot rotated in toward the middle of the body.
- Anterior dislocation. When the thighbone slips out of its socket in a forward direction, the hip will be bent only slightly, and the leg will rotate out and away from the middle of the body.
Causes of hip dislocation
Motor vehicle collisions are the most common cause of traumatic hip dislocations. The dislocation often occurs when the knee hits the dashboard in a collision. This force drives the thigh backwards, which drives the ball head of the femur out of the hip socket. Wearing a seatbelt can greatly reduce your risk of hip dislocation during a collision.
A fall from a significant height (such as from a ladder) or an industrial accident can also generate enough force to dislocate a hip.
With hip dislocations, there are often other related injuries, such as fractures in the pelvis and legs, and back, abdominal, knee, and head injuries. Perhaps the most common fracture occurs when the head of the femur hits and breaks off the back part of the hip socket during the injury. This is called a posterior wall acetabular fracture-dislocation.
Treatment of the hip dislocation
Reduction Procedures
If there are no other injuries, the doctor will administer an anesthetic or a sedative and manipulate the bones back into their proper position. This is called a reduction.
In some cases, the reduction must be done in the operating room with anesthesia. In rare cases, torn soft tissues or small bony fragments block the bone from going back into the socket. When this occurs, surgery is required to remove the loose tissues and correctly position the bones.
