Hip Dislocations

For fractured neck of femur (the much more common hip injury, especially in older patients after a low-energy fall) see Neck of Femur Fracture.

Native hips dislocate more easily in younger patients (bone stronger than ligament/capsule, which gives way first under enough force); total hip replacements can dislocate at lower force depending on prosthesis alignment (straighter alignment → higher dislocation risk). Low-impact/low-force dislocation in a child raises suspicion of an underlying connective tissue disorder.

Infants — screen with the Barlow and Ortolani manoeuvres for posterior hip dislocation/reduction; ultrasound is the gold-standard confirmatory test if concerned. Needs early intervention — delayed diagnosis leads to early hip replacement and lifelong loss of function. See childhood hip disorders (DDH).

Examination

• Posterior dislocation (~90% of cases, the much more common pattern) — hip flexed, adducted and internally rotated, with apparent shortening; higher risk of sciatic nerve injury.
• Anterior dislocation (~10%) — hip abducted and externally rotated (extended if a superior/iliac-pubic dislocation, flexed if an inferior/obturator dislocation); higher risk of femoral vessel or nerve injury.
• Recurrent dislocation can follow the first, from labral tears and capsular instability.

Management

All native hip dislocations need urgent reduction — each hour of delay increases the likelihood of needing surgery and reduces the long-term chance the hip stays reduced. Urgency increases further with absent peripheral pulses or nerve injury. A dislocated hip replacement is equally urgent (comparable pain).

Best practice is reduction in theatre under heavy sedation/analgesia/muscle relaxation, since the surrounding muscles are under significant tension. Rehabilitation is the main non-surgical approach once a stable reduction is achieved.