What does an externally rotated foot with no difference in leg length suggest about the hip dislocation?

An externally rotated foot with no difference in leg length typically indicates an anterior hip dislocation. In this type of dislocation, the femoral head is displaced forward (anteriorly) out of the acetabulum, often resulting in the affected leg being in an externally rotated position. This external rotation occurs because of the position of the muscles and ligaments that stabilize the hip joint, which are altered when dislocation takes place.

The absence of leg length discrepancy supports this diagnosis, as anterior dislocations do not typically cause a shortening of the femur or a significant alteration in the relative lengths of the legs, unlike some posterior dislocations where the leg may appear shorter due to the positioning of the femur. Understanding the mechanics of hip dislocation and the associated symptoms helps clarify the significance of the foot’s position and the leg’s relative lengths in diagnosing the type of hip dislocation.