Year : 2002 | Volume
: 36 | Issue : 1 | Page : 4-
Mechanism of injury
Avan Orthopaedic Hospital, Surat, India
Avan Orthopaedic Hospital, Makkai Pul, Nanpura,Surat, 395001
|How to cite this article:|
Desai D. Mechanism of injury.Indian J Orthop 2002;36:4-4
|How to cite this URL:|
Desai D. Mechanism of injury. Indian J Orthop [serial online] 2002 [cited 2020 Jan 27 ];36:4-4
Available from: http://www.ijoonline.com/text.asp?2002/36/1/4/35911
The acetabulum is either fractured by the femoral head, which transmits the force received on the greater trochanter, or through the impact on the flexed knee, or on the foot with knee extended. There is, therefore, a frequent association with fractures of the lower extremity. Injuries to the patella and to the posterior cruciate ligament are common and are often overlooked. At the same time, damage to the articular surface of femoral head must always be suspected with any acetabular fracture.
The pathological anatomy of the fracture depends on the position of the femoral head at the moment of impact. The femoral head acts as a hammer against the acetabulum, producing the injury. There are two basic mechanisms of the injury.
A blow directly on the greater trochanter usually causes a transverse type of acetabular fracture, depending on the degree of abduction and rotation of the femoral head.
Dashboard injuries are caused when the flexed knee joint strikes the dashboard of the motor vehicle, driving the femur posteriorly on to the acetabulum causing principally posterior wall fractures of all types, including those associated with posterior column or transverse fractures. Posterior dislocation of the hip is also prevalent with this injury.
In general the externally rotated hip causes injuries to the anterior column, the internally rotated hip to the posterior column, the abducted hip causes a low transverse fracture, the adducted hip a high transverse fracture. 
Majority of acetabular fractures are caused due to motor vehicle accidents to the occupants of the vehicle, some occur in pedestrians injured in motor vehicle accidents and still fewer are seen as a consequence of a fall from height or compression by a heavy object or animal.
The actual fracture or fracture dislocation produced depends on the magnitude of the force causing it, as well as on the strength of the bone. Comminution with articular impaction is common. Older patients with osteoporosis may fracture the acetabulum with relatively low force, resulting from simple falls.
High-energy injuries have a high incidence of major associated injuries, whereas low energy injuries are usually isolated.
|1||Letournel E. Fractures of the Acetabulum. Elson RA (ed). Berlin; Springer - Verlag. 1993.|