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Hip dislocation - Fracture clinics
Hip dislocation in children is rare. It is generally a result of significant trauma.
The key to clinical diagnosis is the abnormal position of the limb, which would not occur with a fractured femur.
All hip dislocations require reduction in theatre and should have prompt orthopedic assessment.
Hip dislocations can be described by the direction of the dislocation. The femoral head can be dislocated posteriorly (most common), anteriorly or very rarely inferiorly.
Hip dislocations can also be described by presence of associated injuries:
These are rare injuries. In older children, they usually result from significant trauma. In younger children (<5 years) hip dislocation can occur after minor trauma.
The key to clinical diagnosis is the abnormal position of the limb, which would not occur with a fractured femur
The patient will be uncomfortable and not want to move the affected leg. The affected leg will appear shorter than the non-injured side. With an anterior dislocation, the leg is usually abducted and externally rotated. With a posterior dislocation the leg is usually adducted and internally rotated with the hip in a flexed position.
Anteroposterior (AP) pelvis x-ray should be obtained. A post-reduction CT can be ordered if there are any concerns for a non-congruent reduction or bone fragments in he joint.
Figure 1: Posterior dislocation of the hip.
All hip dislocations need prompt reduction. This is ideally performed in the operating theatre, to allow for careful and controlled relocation. Occasionally, restrictions of access to the theatre may require reduction to be done in the ED.
All hip dislocations should have prompt orthopedic assessment.
All hip dislocations should have prompt orthopedic assessment. Ensure that adequate analgesia is provided and screen for any other injuries.
Any follow-up should be arranged by the orthopaedic service.
The child will be assessed and treated by the nearest orthopaedic on call service. There can be complications associated with this injury, which the orthopedic team will discuss with parents.
Avascular necrosis (AVN) of the femoral head is the most common complication. This can occur due to disruption of the blood supply to the femoral head as a result of the injury. The risk is reported between 3-15%. The risk has been shown to be significantly if the hip is not reduced within 6 hours post-injury.
Other complications are less common, but include nerve injury (2-10%), femoral head over growth (coxa magna), osteoarthritis (those injuries with acetabular fractures), recurrent dislocation and growth arrest.
See fracture clinics for other potential complications.
McCarthy JM, Noonan K. Fractures and traumatic dislocations of the hip in children. In Rockwood and Wilkins' Fractures in Children, 7th Ed. Beaty JH, Kasser JR (Eds). Lippincott Williams & Wilkins, Philadelphia 2010. p.769-96.
Vialle R, Odent T, Pannier S, et al. Traumatic hip dislocation in childhood. J Pediat Ortho 2005; 25(2): 138-44.