Dislocation fracture of the femoral head in adult.

The smaller the head fragment, the more likely it is located at the bottom and in front of the femoral head, which then determines the most suitable approach. A CT scan is essential after reduction and before resumption of weight-bearing to verify the size and congruence of the fragments and whether there are foreign bodies and/or a fracture of the posterior wall. Classifications should include the size of the fragment and whether or not there is an associated fracture of the acetabulum or femoral neck (historical 'Pipkin', modernised 'Chiron'). In an emergency, the dislocation should be rectified, without completing the fracture (sciatic nerve palsy should be diagnosed before reduction). A hip prosthesis may be indicated (age or associated cervical fracture). Delayed orthopaedic treatment is sufficient if congruence is good. A displaced fragment can be resected (foreign bodies and ¼ head), reduced and osteosynthesised (⅓ and ½ head), and a posterior wall fracture reduced and osteosynthesised. Small fragments can be resected under arthroscopy. The approach is medial (Luddloff, Ferguson, Chiron) to remove or osteosynthesise ⅓ or ¼ fragments; posterior for ½ head or a fractured posterior wall. The results remain quite good in case of resection or an adequately reduced fragment. Long-term osteoarthritis is common (32%) but well tolerated with a low rate of prosthetisation. Avascular necrosis remains a possible complication (8.2%). Sciatic nerve palsy (4% of fracture dislocations) is more common for dislocations associated with posterior wall fractures.