Hip dislocations can occur posteriorly or anteriorly;
however, any type of hip dislocation is considered an emergency.
Posterior hip dislocations are more common and the lower
limb will be flexed, adducted, and internally rotated. Posterior dislocations
are frequently caused by dashboard injuries. The impact with the car dashboard
drives the femoral head backwards out of the acetabulum. The physician will
want to observe sciatic nerve function and examine the knee to rule out a PCL
injury as well. Weakness of the ankle and toe dorsiflexion due to an injury to
the peroneal division of the sciatic nerve may result in foot drop. The patient
will also be unable to dorsiflex the ankle.
Anterior hip dislocation is rare. Superior Anterior hip
dislocation results from the lower limb being extended, abducted, and
externally rotated. Inferior Anterior Hip Dislocations (obturator type) results
from the lower limb being flexed, abducted, and externally rotated.
An emergency reduction of dislocations is needed in less
than 8 hours of the injury. An urgent reduction is mandatory to avoid avascular
necrosis and interruption of the blood supply, which leads to a collapse of the
femoral head. AVN is the death of a segment of bone.
Treatment
A CT scan should be obtained after reduction to evaluate the
presence of fragments in the joint and access stability of the joint. Hip joint
dislocations may be associated with acetabular or femoral head fractures (Pipkin).
An urgent closed reduction of the hip dislocation followed by stabilization of
either of the fractures if needed according to the protocols.
