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Hip dislocations are true orthopedic emergencies. The Emergency Physician (EP) must be capable of reducing a dislocated hip. Neurovascular damage to the hip and leg is a consequence of a hip dislocation. Avascular necrosis (AVN) may occur in up to 20% of patients with a hip dislocation. Other studies show that AVN following a hip dislocation is a time-dependent phenomenon. The longer a hip is dislocated, the higher the incidence of avascular necrosis. Dislocation of a hip for more than 6 hours almost universally results in this devastating complication.
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The main etiologies of a hip dislocation are traumatic dislocations of a normal hip, mechanical dislocations of a prosthetic hip, spontaneous dislocations, and pathologic dislocations. Less impressive mechanisms may result in hip dislocations in the young and the elderly. A simple fall from standing may dislocate a geriatric hip. Dislocations may occur with minor force in children, as during athletic activities.
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Many techniques have been described to reduce dislocated hips.1–7 The EP must be familiar with some of these methods and how to apply them appropriately to optimize patient management and outcome. Dislocations of both normal and prosthetic hips are seen in the Emergency Department. Dislocations of prosthetic hips are now more common than those of normal hips.8 While these are not associated with avascular necrosis, the pressure from the dislocated prosthetic head may result in other neurovascular complications.
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Ball-and-socket joints are inherently stable. The strong muscles, ligaments, and fibrous joint capsule of the hip reinforce this innate stability. Consequently, in the average adult, a great deal of force must be transmitted to dislocate the hip. This is significant, as the patient with a hip dislocation may have other life-threatening injuries that take precedence over the management of the hip dislocation. The mortality associated with a hip dislocation results from associated injuries of the head, thorax, or pelvis.
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Hip dislocations are classified into anterior, posterior, and central based upon the relationship of the dislocated femoral head to the acetabulum. Anterior hip dislocations occur with the leg in a neutral or abducted position. The femoral head is pushed anterior to the coronal plane of the acetabulum. These patients present in extreme pain with the hip and knee flexed 90°. The leg will be held in external rotation. A slight shortening of the leg may be noted, but this is difficult to detect with the knee in flexion. There are three subtypes of an anterior hip dislocation: anterior obturator, anterior iliac, and anterior pubic. The femoral head displaces medially and lies in the obturator canal in anterior obturator dislocations. The femoral head moves superiorly and lies over the iliac wing in anterior iliac dislocations. The femoral head moves inferiorly over the pubic ramus in anterior pubic dislocations.
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Posterior hip dislocations are the most common type. They account for nearly 90% of all hip dislocations. This is because the posterolateral half of ...