Hip dislocation is a relatively rare entity and may be congenital or acquired.
Epidemiology
Hip dislocations account for ~5% of all dislocations 3.
Pathology
There are numerous patterns of dislocation 1:
posterior hip dislocation (most common ~85%)
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anterior hip dislocation (~10%)
inferior (obturator) hip dislocation
superior (pubic/iliac) hip dislocation (rare)
central hip dislocation - always associated with acetabular fracture 2,3
Hip dislocation can be further classified as being simple (pure without associated fracture) or complex (dislocation associated fracture of the acetabulum or proximal femur) 6.
Etiology
Acquired
Acquired hip dislocation is normally associated with high-speed trauma, with motor vehicle collisions accounting for half of the dislocations with other causes such as falls and sports injuries, less common 1.
Hip dislocation is the second most common complication of hip joint replacements and occurs in ~5% (range 0.5-10%) of patients with ~60% of dislocations being recurrent 5.
Congenital
Congenital hip dislocation is now considered part of the spectrum of developmental dysplasia of the hip 4.
Complications
avascular necrosis: particularly if reduction postponed more than 24 hours