A 37-year-old woman is brought to the emergency department following a motor vehicle collision. She lost control of her car while going around a corner and struck a brick wall head on. The patient has severe pain at the right hip with any movement. Examination shows that the right lower extremity is adducted and internally rotated and appears shorter than the contralateral leg. Range of motion testing at the hip is limited in all directions due to severe pain. X-ray of the hip is shown in the exhibit.

Which of the following structures is most vulnerable to involvement from this patient's injury?

Question

A 37-year-old woman is brought to the emergency department following a motor vehicle collision. She lost control of her car while going around a corner and struck a brick wall head on. The patient has severe pain at the right hip with any movement. Examination shows that the right lower extremity is adducted and internally rotated and appears shorter than the contralateral leg. Range of motion testing at the hip is limited in all directions due to severe pain. X-ray of the hip is shown in the exhibit.

Which of the following structures is most vulnerable to involvement from this patient's injury?

Quizplus · Accepted Answer

11ec160b_35e5_b36f_9249_6352ecd3e2d4_MD0001_00 This patient has a posterior hip dislocation (ie, femoral head displaced posteriorly from the acetabulum), which commonly occurs in head-on motor vehicle collisions in which the knee strikes the dashboard or from a fall in frail, elderly patients. The risk is increased with prosthetic joints. On examination, the leg with a posterior hip dislocation appears shortened and internally rotated, with the hip held in flexion and adduction. Range of motion is limited and painful. Posterior dislocation can be mistaken for intertrochanteric hip fracture, which can also present with leg shortening; however, the leg is typically rotated externally with intertrochanteric fracture due to contraction of the psoas and iliacus without the normal acetabular counterforce. The sciatic nerve runs posterior to the hip joint and is vulnerable to injury with posterior hip dislocation. Findings of sciatic injury include weakness of ankle dorsiflexion, decreased ankle reflex, and decreased sensation in the distribution of the nerve. (Choices A and B) The femoral artery runs anterior to the hip and can be injured in anterior (not posterior) dislocation, which is rare and typically occurs in association with additional traumatic injuries (eg, hip fracture); examination shows abduction and external rotation of the thigh. The femoral nerve also runs anterior to the hip joint; it is occasionally injured in hip arthroplasty but is not at risk in posterior dislocation. (Choice C) The lateral femoral cutaneous nerve passes under the inguinal ligament into the lateral thigh; it is vulnerable to external compression but is not at risk in hip dislocation. (Choice E) The superior gluteal artery arises from the internal iliac artery in the posterior pelvis and can be injured in pelvic fracture. It does not approximate the hip joint and is not vulnerable in posterior dislocation. Educational objective: Posterior hip dislocation (ie, femoral head displaced posteriorly from the acetabulum) can occur in motor vehicle collisions in which the knee strikes the dashboard or from falls in elderly patients. On examination, the leg appears shortened and internally rotated, with the hip held in flexion and adduction. The sciatic nerve is vulnerable to injury in posterior hip dislocation.

A 37-Year-Old Woman Is Brought to the Emergency Department Following