Hip dislocation is a relatively rare entity and may be congenital or acquired. It has a relatively high morbidity.

Epidemiology

Hip dislocations account for ~5% of all dislocations ³. 

Pathology

There are numerous patterns of dislocation ^1,9:

• posterior hip dislocation (most common ~85%)

• 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:

• simple: pure without associated fracture; less common (~15%) ^6,9

• complex: dislocation-associated acetabular rim (~45%) or femoral head fractures (~40%) ^6,9

Etiology

Acquired

Traumatic hip dislocations are normally associated with high-speed trauma, with motor vehicle collisions accounting for majority (~80%) of the dislocations with minor trauma, e.g. falls (~10%), sports injuries (~10%), far less common ^1,9. Redislocation after a traumatic hip dislocation is uncommon (~1%) ⁹.

Non-traumatic dislocations can occur in cerebral palsy patients ^7,8, and as a complication of hip joint replacements; occurring 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. 

Associations

• multitrauma (~40%) ⁹

• concomitant knee injuries (~30%), in particular posterior cruciate ligament rupture and knee fracture ⁹

Treatment and prognosis

Traumatic hip dislocations can be treated with closed reduction (under anesthesia with muscle relaxants) or open reduction, particularly if there is an associated fracture or after failed closed reduction ⁹.

A significant proportion (~30%) of patients will not return pre-injury occupation or level of sport ⁹. Approximately ~20% will undergo subsequent total hip replacement ⁹.

Complications

• post-traumatic osteoarthritis: ~30% of patients ⁹

• sciatic nerve injury: ~27.5% of patients ⁹

  • associated with Pipkin type IV femoral head and posterior acteabular rim fractures ⁹

  • may be transient, or chronic in ~10% of patients ⁹

• sexual dysfunction: ~27.5% of patients ⁹

• femoral head osteonecrosis: ~15% of patients ⁹

  • more likely in older patients ⁹

  • risk related to time to hip reduction is controversial ⁹