Traumatic hip dislocation

Traumatic dislocation of the hip refers to dislocation of the femoral head from the acetabular socket. It is rare and usually associated with other injuries, like acetabular fracture or hip fracture. It mostly occurs due to high energy trauma in young. 90% of traumatic hip dislocations are posterior.

It may lead to osteonecrosis of the femoral head, osteoarthritis, and sciatic nerve injury.

Classification

Hip dislocations are classified according to their direction, posterior or anterior.

Posterior hip dislocation accounts for 90% of cases and occurs due to axial load on the femur with the hip in a flexed and adducted position. This is the usual position when sitting in a car, in which case the force from the dashboard pushes on the femur, therefore called a “dashboard injury”.

Anterior hip dislocations are rare. They occur when the hip is in an abducted and externally rotated position, which is rare in vehicles.

Clinical features

In both types there is hip pain, which usually radiates to the knee. In posterior dislocation the leg is shortened and internally rotated. In anterior dislocation the leg is lengthened and externally rotated.

Diagnosis and evaluation

Initial evaluation is usually with x-ray, but proper evaluation requires CT to look for associated injuries.

Treatment

Treatment is closed reduction if the injury is < 6 hours old. Closed reduction should always be followed up by CT. Surgery is indicated if closed reduction is unsuccessful, the joint is unstable, or if there are fragments in the joint.