Examkin

Question

Difficulty: MediumOrthopedic Surgery

A 31-year-old woman is brought to the emergency department after a high-speed motor vehicle collision. She was an unrestrained front-seat passenger, and her knees forcibly struck the dashboard during the impact. She is in severe distress and complains of excruciating right hip pain. Vital signs are temperature 37.1°C (98.8°F), pulse 105/min, blood pressure 122/78 mm Hg, and respirations 18/min. On physical examination, the right lower extremity is shortened, adducted, and internally rotated. Peripheral pulses are 2+ and symmetric. Neurologic examination reveals decreased sensation to pinprick over the dorsum of the right foot and an inability to actively dorsiflex the right ankle. Anteroposterior radiographs of the pelvis demonstrate a posterior dislocation of the right femoral head with no obvious displaced acetabular or femoral neck fractures. Which of the following is the most appropriate next step in management?

  1. A
    Computed tomography scan of the right hip and pelvis
  2. B
    Measurement of compartment pressures in the right lower extremity
  3. Urgent closed reduction of the hipAnswer
  4. D
    Immediate open surgical exploration of the sciatic nerve
  5. E
    Administration of prophylactic intravenous broad-spectrum antibiotics

Answer

The most appropriate next step in management is urgent closed reduction of the hip.
Posterior hip dislocations are orthopedic emergencies. The mechanism (dashboard injury) and presentation (shortened, adducted, internally rotated leg) are classic. The sciatic nerve is frequently stretched or compressed by the displaced femoral head, causing foot drop and dorsal foot numbness. The standard of care is immediate closed reduction (ideally within 6 hours) to relieve pressure on the nerve and significantly reduce the risk of avascular necrosis of the femoral head.

Step-by-Step Solution

1
Identify the injury pattern based on the physical examination and mechanism.
The patient has a shortened, adducted, and internally rotated right lower extremity after a dashboard injury, which is the classic presentation of a posterior hip dislocation.
Recognizing the specific anatomic deformity is necessary to guide emergent management and anticipate potential complications.
2
Correlate the neurologic deficit with the anatomical injury.
Foot drop and dorsal foot numbness indicate a sciatic nerve injury (specifically the peroneal division), which is a known complication of posterior hip dislocations due to posterior displacement of the femoral head.
Understanding the cause of the nerve deficit confirms that the primary problem is mechanical compression or stretch from the dislocated joint.
3
Determine the most appropriate immediate intervention.
Urgent closed reduction is required to relieve tension on the sciatic nerve and restore blood supply to the femoral head.
Delaying reduction for advanced imaging or pursuing unnecessary surgical exploration increases the risk of permanent neurologic disability and avascular necrosis.

Key Concept

Emergent closed reduction of posterior hip dislocations to prevent avascular necrosis and relieve sciatic nerve traction.
Estimated Time:1m 0s
Rate this question

Topics

Orthopedic Surgery

More questions from this topic