WORKUP	Section 5 of 10
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Bibliography

Lab Studies:

• No laboratory tests specifically assist in the diagnosis of hip dislocation.

• Depending on the mechanism of injury and the patient's clinical presentation, a variety of tests may be indicated in the overall workup for trauma

• Determination of CBC including serial spun hematocrits

• Urinalysis

• Typing and cross-matching for blood

• In certain circumstances - Pregnancy test, toxicology screen, and/or assessment of the coagulation profile and/or serum chemistry panel

Imaging Studies:

• Plain radiography

• Plain radiographs of the pelvis should routinely be obtained in patients with a severe mechanism of injury, such as a MVA or fall from a substantial height. Pelvic fractures may occur in as many as 10% of patients. Alert patients with no distracting injuries and no pelvic pain may not need pelvic films.

• The appearance of a hip dislocation may be subtle on a single anteroposterior (AP) pelvis view because the femoral head may lie in an apparently normal position though it is dislocated. Most central dislocations are easily seen on this view. Associated acetabular fractures may be seen as well.

• If a hip dislocation is suspected, AP and lateral images of the involved hip should be obtained. In a posterior dislocation, the femur is adducted and internally rotated, while the head of the femur is situated lateral and superior to the acetabulum. In an anterior dislocation, the femur is abducted and externally rotated, while the head of the femur is medial and inferior to the acetabulum.

• Radiographs of the hip also may reveal concomitant fractures around the head and neck of the femur.

• A Johnson lateral radiograph of the hip lateral view of the hip from the opposite side with the contralateral thigh flexed) can be obtained without moving the involved hip. This view also may reveal the dislocated position (anterior or poster) of the femoral head.

• Although they are not a routine part of the trauma workup, oblique views are useful if a hip dislocation is suspected. Oblique (Judet) views of the pelvis show the anterior and posterior walls of the pelvis as well as each acetabular column separately and may reveal a hip dislocation that was not apparent on the AP view.

• Computed tomography

• CT scan of the hip is accurate in delineating the extent and nature of acetabular and hip fractures and dislocations.

• If the patient's condition is sufficiently stable and if surgical repair is contemplated, CT scans provide essential information for the orthopedist.

• The severity of acetabular fractures tends to be underestimated on plain radiographs, which are therefore less useful than CT scans in this situation.

• Magnetic resonance imaging

• MRI of the hip is usually impractical in the initial evaluation of a trauma patient. It is, however, the best imaging modality in detecting and assessing AVN of the hip and in detecting nondisplaced stress fractures of the femoral neck.

• MRI is also useful in the diagnosis of bone tumors, osteomyelitis, osteoarthritis, and congenital abnormalities of the hip joint.

Other Tests:

• Radionucleotide scanning is a sensitive method that depicts early AVN.

• Radionuclide scanning is currently the criterion standard for diagnosis for AVN, though it is being replaced by MRI, which reveals greater anatomic detail and which appears to be equally sensitive.

	TREATMENT	Section 6 of 10
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Bibliography

Prehospital Care:

• Patients with hip dislocation often have associated injuries that may take precedence during stabilization, both in the field and in the ED. Attempts to reduce the dislocation in the field are ill advised.

• Establish the ABCs with appropriate spinal immobilization.

• If hip dislocation is detected in the field, the patient should be placed on a backboard and allowed to assume the leg position that is most comfortable (ie, hip slightly flexed, leg adducted).

• The patient should be transported to a level of trauma center appropriate for his or her overall clinical status.

Emergency Department Care:

• Patients with hip dislocations often have other injuries that require immediate stabilization or emergency investigation in the ED. Reduction of the dislocation may have to wait until more severe injuries are treated. Intravenous (IV) access is indicated to provide fluid resuscitation and administration of analgesia, as well as other medications as needed.

• Once life-threatening injuries have been stabilized or ruled out, evaluate the hip dislocation. Consult an orthopedic specialist whenever practical.

• Reduction of a hip dislocation should be deferred to the orthopedic specialist, if possible. Emergency physicians should be familiar with reduction techniques, and they should perform the reduction if a specialist is unavailable within a reasonable period (eg, within a 6-hour window from the time of injury) or if a neurovascular deficit is present.

• Even if an orthopedist attempts a closed reduction, the emergency physician can often provide assistance, such as countertraction, during the procedure. The emergency physician is often responsible for the conscious sedation required to perform a closed reduction. Closed reduction can be attempted, even with central dislocations. Urgent indications are the presence of neurovascular deficits or delays in care approaching 6 hours.

• Additional radiographs or a CT scan may be useful in delineating the extent and exact nature of the dislocation and the presence of associated fractures, which may complicate the reduction or stability of the joint after reduction.

• If the patient's vital signs and overall clinical condition permit, adequate analgesia is indicated. Reduction is greatly facilitated by the use of conscious sedation, and a variety of medications may be used for this purpose. A combination of agents with muscle relaxant and analgesic effects is optimal. Monitor the patient appropriately during conscious sedation.

• Once sufficient relaxation has been achieved, initiate attempts at closed reduction using one of the following techniques. Make no more than 3 attempts at closed reduction, as the incidence of AVN increases with multiple attempts.

• The particular approach to reduction should be based on the exact nature of the dislocation and the position of the femoral head in relation to the acetabulum, not on the physician's favorite method. For example, a pure superior dislocation may best be treated by simple longitudinal traction.

• Either of 2 techniques is used most often for reducing a simple posterior hip dislocation.

• Allis maneuver
  • Place patient in supine position under deep conscious sedation (eg, with a methohexital infusion).

  • Monitor vital signs, cardiac rhythm, and pulse oximetry readings.

  • While an assistant stabilizes the pelvis with direct pressure, the operator stands on the bed over the patient.

  • Flex the hip and knee to 90° and apply axial traction with gradually increasing force and a rocking motion until the hip relocates.

  • Additional lateral traction to the proximal femur may help disengage the femoral head and facilitate reduction.

• Stimson maneuver
  • With the patient placed prone on a gurney under deep conscious sedation, allow the dislocated leg to hang over the edge of the bed with the hip and knee at 90° of flexion.

  • With an assistant providing stabilizing pressure to the pelvis, apply force to the calf and gradually increase until relocation is accomplished.

  • Although this technique is often more successful than the Allis technique, it has the disadvantages that the knee may be injured if too great a force is applied to the popliteal area.

  • Monitoring respiration and providing ventilation are difficult with the patient in the prone position.

• Other techniques
  • Reverse Bigelow maneuver: This technique seldom is used in the ED. It involves the application of a firm jerk to a partially flexed thigh while holding the proximal tibia and knee area.

  • Whistler technique: This recently described technique for the ED is relatively simple, and physicians have had success with it. The dislocated hip is relocated using the physician's arm to raise and maneuver the affected leg as the physician's shoulder is raised. The physician's hand rests on the opposite thigh. An assistant provides countertraction on the tibia/fibula.

  • Leg-crossing maneuver: Occasionally, a dislocation can be reduced gently by coaxing the patient to gradually cross the affected leg over the other (adduction) and then applying gentle traction to the leg while an assistant guides the femoral head back into position by direct pressure in an anterior direction.

  • Longitudinal traction: This may be adequate to reduce a purely superior dislocation.

• If relocation of the hip is successful, immobilize the legs in slight abduction by using a pad between the legs to prevent adduction until skeletal traction can be instituted.

• The duration of traction and non–weight-bearing immobilization is controversial. Evidence suggests that early weight bearing (eg, 2 weeks after relocation) may increase the severity of aseptic necrosis when it occurs. Early weight bearing decreases the incidence of other complications (eg, venous thromboembolism, decubiti), and some studies have found equivalent outcomes with early and delayed weight bearing.

• Indications for open reduction

• Irreducible dislocation (approximately 10% of all dislocations)

• Persistent instability of the joint following reduction (eg, fracture-dislocation of the posterior acetabulum)

• Fracture of the femoral head or shaft

• Neurovascular deficits that occur after closed reduction

	MISCELLANEOUS	Section 9 of 10
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Bibliography

Medical/Legal Pitfalls:

• Failure to diagnose hip dislocation can be the basis for medical liability because delayed diagnosis (>6 hours after dislocation) is associated with a poor prognosis.

• Failure to promptly transfer the patient to an orthopedic specialist at an early stage may be the basis for liability. Because transfer inevitably occurs at an early stage, delayed complications are not usually a source of liability for emergency physicians, but they may be for the orthopedist.

• Clinical pitfalls in the management of hip dislocation include the following:

• Failure to diagnose hip dislocation in the presence of associated femoral-shaft fracture is a pitfall.

• Reliance on a single AP pelvis radiograph may result in a missed posterior hip dislocation because the femoral head appears to be in the proper place

• Ascribing hemorrhagic shock to blood loss associated with a hip fracture (eg, missing associated intrathoracic or intra-abdominal injuries)

• Failure to test femoral and sciatic nerve function and distal perfusion before and after attempts at closed reduction

Special Concerns:

• Patients with dislocation of a prosthetic hip

• Hip prostheses frequently deteriorate over time and may dislocate with minimal trauma, such as crossing the legs.

• Reducing such dislocations is less urgent than reducing acute dislocation, as the concern regarding AVN and osteoarthritis is nonexistent.

• Reduction is accomplished in identical fashion and treatment is the same as for nonprosthetic hips, but these patients can be mobilized to bear weight sooner than those with nonprosthetic hip dislocation.

• Neonates

• Developmental dysplasia of the hip is a common problem that can result in dislocation or severe deformity of the hip joint.

• Patients are routinely screened for this condition during the initial newborn examination by the Ortolani test (ie, eliciting a click on passive abduction of the flexed hip). Although this situation rarely arises in the ED, this test should be part of the normal newborn examination.

• Patients with Down syndrome are more susceptible than others to hip dislocation.

• Children

• If an increased acetabular angle is noted, that is, an increased slope in a line drawn from the upper outermost acetabulum to the center of the acetabulum, this is a sign of possible acetabular dysplasia or subluxation. This condition warrants further investigation.

• Children may dislocate a hip more easily and with a lesser mechanism of injury than adults. Interpretation of radiographs is complicated by the presence of open epiphyses. Salter fractures may occur.

• Reduction should be accomplished in very gentle fashion, under general anesthesia or deep conscious sedation, to avoid producing iatrogenic fracture, slipped capital femoral epiphysis, or other epiphyseal injury.