Definition
- Traumatic displacement of the femoral head out of the acetabulum
- Posterior dislocation accounts for about 90%
Aetiology
- High energy injury, often motor vehicle trauma
- Posterior from axial load on a flexed adducted hip (dashboard injury)
- Anterior from forced abduction and external rotation
Classification
Thompson and Epstein (posterior)
| Type | Description |
|---|---|
| I | Simple or minor posterior wall fragment |
| II | Large single posterior wall fragment |
| III | Comminuted posterior wall |
| IV | Acetabular floor fracture |
| V | Femoral head fracture |
Original publication Thompson VP, Epstein HC. Traumatic dislocation of the hip; a survey of two hundred and four cases covering a period of twenty-one years. J Bone Joint Surg Am. 1951;33-A(3):746-78; passim.
Pipkin (femoral head fractures)
| Type | Description |
|---|---|
| I | Below the fovea |
| II | Above the fovea |
| III | With femoral neck fracture |
| IV | With acetabular fracture |
Original publication Pipkin G. Treatment of grade IV fracture-dislocation of the hip. J Bone Joint Surg Am. 1957;39-A(5):1027-42 passim.
Clinical Features
- Posterior dislocation holds the limb flexed, adducted, internally rotated and shortened
- Anterior dislocation holds the limb extended or flexed, abducted and externally rotated
- Sciatic nerve injury in posterior dislocation, mostly the peroneal division
- Look for ipsilateral knee injury, femoral shaft fracture and patellar fracture
Investigations
- AP pelvis and lateral hip before reduction
- Check the femoral neck for fracture before any closed manoeuvre
- CT after reduction for congruency, loose bodies and fractures
Management
- Emergency closed reduction under GA or deep sedation, ideally within 6 hours
- Allis, Stimson or Bigelow manoeuvres
- Test stability after reduction under fluoroscopy
- Open reduction for irreducible dislocation, femoral neck fracture or nonconcentric reduction
- ORIF of unstable posterior wall or displaced femoral head fractures
- Arthroscopic or open removal of intra-articular fragments
Complications
- Avascular necrosis, more likely with delayed reduction
- Post-traumatic arthritis, the most frequent long term complication
- Sciatic nerve palsy, partial recovery in many
- Heterotopic ossification
- Recurrent dislocation is uncommon
Prognosis
- Simple dislocations reduced early have good outcomes in most patients
- Associated fractures worsen outcomes
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.