Anterior dislocation of the hip

Anterior hip dislocation is much less common than a posterior hip dislocation. It constitutes for only 5-18% of all hip dislocations.

Pathology

While the posterior dislocation is often associated with fractures, the anterior dislocation is mostly an isolated injury 1.

Subtypes

It can be classified into superior and inferior subtypes.

Radiographic features

Plain radiograph

Radiographic signs of an anterior hip dislocation are the lesser trochanter being more visible due to external rotation. The hip is abducted, and the femur head is usually inferior to the acetabulum. Shenton's line is also broken.

Whereas inferior anterior hip dislocation is easily recognised on an anteroposterior radiograph of the pelvis, the radiographic appearance of superior anterior hip dislocation is less straightforward, often leading to an initial misdiagnosis of posterior hip dislocation. Two radiologic findings may help to distinguish these two from each other:

  • lesser trochanter more visible in anterior dislocation due to external rotation
  • femoral head will appear larger than the contralateral hip on account of geometric magnification
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Article Information

rID: 14838
Tags: refs, cases
Synonyms or Alternate Spellings:
  • Anterior dislocations of the hip
  • Anterior hip dislocation

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