Image of the Day 4: Anterior Hip Dislocation

This Pelvis X Ray shows a very typical feature of anterior left hip dislocation. The features are as follow 1) Prominent lesser trochanter, 2) Hip is in abducted position, 3) Femur head is inferior to acetabulum and 4) Disrupted shenton line.

Anterior hip dislocation rarely occur and constitutes about 5-10 % of all hip dislocation. In contrast to posterior hip dislocation that associates with fracture, anterior hip dislocation usually occur in isolation. If to be associated with fracture, the percentage is very low and may involve impaction fracture of femoral head and acetabulum fracture.

Anterior hip dislocation could further be classified into two main type which are superior and inferior. In superior dislocation, the femoral head is displaced into the iliac or pubic region. Meanwhile, in inferior anterior hip dislocation, the femoral head lies in the obturator region.

Mechanism of injury usually involves hyperextension of the abducted leg that will levers the femoral head out of acetabulum.

Often, this mode of injury will require open reduction and stabilization of the dislocted femoral head. Leave untreated, it may lead to neglected dislocation causing early osteoarthritis and requiring total hip replacement surgery.