Hip Dislocation in Emergency Medicine Follow-up

Various techniques can be used to accomplish open reduction, acetabular repair, and fixation of associated fractures; these techniques are beyond the scope of this article.

After reduction of the hip dislocation, obtain repeat AP and lateral radiographs of the hip to verify proper reduction.

After either open or closed reduction of a hip dislocation, the patient is instructed to remain on bed rest with his or her legs abducted and with skeletal traction designed to keep the hip from displacing posteriorly.

The duration of traction is approximately 2 weeks, but the recommended period with no weight bearing is controversial and varies from 9 days to 3 months.

An MRI 2-3 months after reduction can verify proper location and to screen for complications, such as avascular necrosis (AVN), osteoarthritis, and heterotopic calcification, at an early stage.

Aggressive rehabilitation should be scheduled as soon as the patient can bear weight.

Patients with AVN or severe osteoarthritis after a hip dislocation may require replacement of the hip with a prosthetic joint.

Appropriate analgesics and sedatives are required during hospitalization.

Nonsteroidal anti-inflammatory medications (NSAIDs) may be required on an outpatient basis.

Once stabilized, patients with multiple trauma may be transferred.

A patient with an isolated hip dislocation may be transferred if no neurovascular deficit is suspected and if the transfer time does not extend the dislocation time by longer than 6 hours.

In general, hip dislocations are reduced at the receiving facility and, if necessary, the patient is transferred for ongoing inpatient care with appropriate immobilization en route.

AVN of the hip

AVN is common, occurring in 8-13% of patients.

Early diagnosis and treatment of dislocations decreases the incidence of AVN.

The effect of early weight bearing on the occurrence of AVN is controversial. Most studies have shown that early weight bearing after reduction is associated with more severe AVN, but it does not appear to increase the incidence.

The incidence of AVN is increased with delayed reduction, repeated attempts at reduction, and open reduction (40% vs 15.5% with closed reduction). This finding may be due to operative trauma or because those dislocations requiring surgery are inherently more severe.

AVN may not become apparent on plain radiographs for several months. Early diagnosis can be made with MRI or nuclear scanning, and these modalities should be considered in a patient who develops late and persistent pain after a dislocation.

Sciatic nerve injury (posterior dislocation)

Injury to the sciatic nerve occurs in 10-14% of posterior dislocations during the initial trauma or during relocation.

Function of the sciatic nerve should be verified before and after relocation to detect this complication. The finding of sciatic nerve dysfunction mandates surgical exploration to release or repair the nerve.

Femoral-nerve injury

Anterior dislocations are occasionally associated with injury to the femoral artery or nerve.

Dislocations in children can occur with relatively minor trauma (eg, sports activities), and reduction must be gentle to avoid iatrogenic injury to the femoral epiphysis (eg, slipped capital femoral epiphysis).

Other complications

Other complications of hip dislocation are the following:

• Osteoarthritis
• Heterotopic calcification
• Recurrent dislocation
• Ligamentous injury of the knee, other fractures
• Complications of immobilization (DVT, pulmonary embolus, decubiti, pneumonia)
• Femoral-artery injury (in anterior dislocations)

The prognosis of the patient with a hip dislocation varies with the type of dislocation, with the associated fractures of the femoral head or acetabulum, and the presence of other injuries. Overall, good-to-excellent results are obtained in 50-93% of patients.

The principal determinants of a poor prognosis are as follows:

• AVN occurs in 4-21.8% of patients in some reviews and 8-13% in others. The incidence is increased with delays in reduction beyond 6 hours and with open reduction. The severity of AVN increases in patients who undergo early weight bearing. AVN is a severe complication that usually requires replacement with a prosthetic hip.
• Severe osteoarthritis occurs in at least 10% of patients and is more common in older patients. This seems to be an increased incidence compared to populations without hip dislocations of a similar age, and some authors have found the incidence to range from 30-71% after open reduction.
• Injury to either the femoral or sciatic nerve usually consists of a neurapraxia, and eventual recovery of function can be expected in these cases. Permanent injury to these nerves can occur, resulting in disabling deficits. If patients have a neurological deficit, surgery is usually not indicated. Electromyography can help determine prognosis.
• Recurrent dislocation is a complication if supporting ligaments have been disrupted.

For excellent patient education resources, visit eMedicine's Breaks, Fractures, and Dislocations Center. Also, see eMedicine's patient education article Total Hip Replacement.