Upon discharge, she had continued full range of motion, no pain and no evidence of redislocation. She was followed-up by the orthopedic service for several months. Falls are the single most common cause followed by high velocity injuries such as motor vehicle accidents and sports-related incidents. Boys are more frequently affected than girls. It may also be seen in relatively minor trauma in young children less than 5 years of age due perhaps to joint laxity and a shallow acetabular fossa.
Posterior dislocations are more common than anterior dislocations.
These injuries often occur after a blow to the knee with the hip and knee in flexion, as in a motor vehicle crash with an unrestrained child striking one knee against the dashboard. The leg would be adducted, flexed and internally rotated at the hip, as in this case. There is a relative shortening of the extremity and protrusion of the greater trochanter into the gluteal region. Anterior dislocations, on the other hand, are usually caused by an excessive external rotation or a direct blow to the greater trochanter with the hip externally rotated. The leg would typically be held in abduction, extension and external rotation.