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Pelvic & Acetabular Trauma MCQs

Practice Set 20 of 35

This practice set contains high-yield board review questions covering key concepts in Pelvic & Acetabular Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 381

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 45-year-old woman is brought to the trauma bay after a crush injury. Radiographs show an anterior-posterior compression type III (APC-III) pelvic ring injury with complete disruption of the sacroiliac joints. The initial management to stabilize the pelvic volume should be placement of a pelvic binder centered over which of the following anatomic landmarks?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Symphysis pubis
. Lumbosacral junction

Correct Answer & Explanation

. Greater trochanters

Explanation

A pelvic binder must be centered over the greater trochanters to effectively close the pelvic ring and reduce pelvic volume. Placement over the iliac crests is incorrect and can paradoxically worsen the deformity.

Question 382

Topic: Pelvic & Acetabular Trauma
A 38-year-old woman is evaluated for a closed pelvic ring injury after a pedestrian-versus-auto accident. Examination reveals a large, fluctuant soft-tissue swelling over the greater trochanter with overlying skin ecchymosis and decreased sensation. What is the pathophysiology of this associated soft-tissue injury?
. Rupture of the deep fascia with muscle herniation
. Shearing of the subcutaneous tissue from the underlying fascia, disrupting perforating vessels
. Acute hematogenous spread of bacteria to a local hematoma
. Direct arterial laceration by a bone spike
. Venous thrombosis of the superficial venous system

Correct Answer & Explanation

. Shearing of the subcutaneous tissue from the underlying fascia, disrupting perforating vessels

Explanation

This describes a Morel-Lavallée lesion, a closed degloving injury where subcutaneous tissue is sheared off the underlying fascia. This disrupts perforating vessels, creating a cavity that fills with blood, lymph, and necrotic fat.

Question 383

Topic: Pelvic & Acetabular Trauma
A 35-year-old man presents with an anteroposterior compression type III (APC-III) pelvic ring injury following a motorcycle collision. He arrives hypotensive, and a pelvic binder is applied. After receiving 2 units of packed red blood cells, his blood pressure remains 75/40 mm Hg. A Focused Assessment with Sonography for Trauma (FAST) exam is negative. What is the most appropriate next step in management?
. Immediate exploratory laparotomy
. Application of a spanning anterior external fixator
. Preperitoneal pelvic packing or pelvic angiography
. Definitive open reduction and internal fixation of the symphysis pubis
. Bilateral internal iliac artery ligation

Correct Answer & Explanation

. Preperitoneal pelvic packing or pelvic angiography

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, the source of bleeding is likely retroperitoneal. Preperitoneal pelvic packing or pelvic angiography with embolization are the interventions of choice. Exploratory laparotomy is contraindicated for isolated extraperitoneal bleeding.

Question 384

Topic: Pelvic & Acetabular Trauma
An unrestrained driver presents hypotensive and tachycardic after a high-speed collision. Pelvic radiographs reveal an anteroposterior compression (APC) type III pelvic ring injury with complete disruption of the sacroiliac joints. Which of the following is the most appropriate initial step in acute orthopedic management?
. Immediate application of an external fixator
. Application of a pelvic binder centered over the iliac crests
. Application of a pelvic binder centered over the greater trochanters
. Emergent pelvic angiography with embolization
. Immediate retroperitoneal packing

Correct Answer & Explanation

. Application of a pelvic binder centered over the greater trochanters

Explanation

In a hemodynamically unstable patient with an open-book pelvic ring injury, the initial orthopedic step is reducing pelvic volume to assist in tamponading venous bleeding. A pelvic binder must be centered over the greater trochanters to effectively close the pelvic ring; placement over the iliac crests is ineffective and can paradoxically widen the pelvis.

Question 385

Topic: Pelvic & Acetabular Trauma

In a hemodynamically unstable trauma patient with an anteroposterior compression (APC) pelvic ring injury, where is the optimal anatomical location for the application of a circumferential pelvic binder?

. Directly over the iliac crests
. Directly over the greater trochanters
. Directly over the anterior superior iliac spines
. Directly over the pubic symphysis
. Centered over the lumbar spine and lower abdomen

Correct Answer & Explanation

. Directly over the greater trochanters

Explanation

A pelvic binder must be positioned directly over the greater trochanters to effectively close the pelvic volume and provide maximum compressive tamponade on the bleeding presacral venous plexus.

Question 386

Topic: Pelvic & Acetabular Trauma
A 25-year-old male is brought to the ED after a motorcycle collision. He is hemodynamically unstable. A pelvic radiograph shows an APC-III pelvic ring injury. Where should a pelvic binder be applied to most effectively reduce the pelvic volume?
. At the level of the iliac crests
. At the level of the anterior superior iliac spines
. At the level of the greater trochanters
. Around the proximal thighs
. At the level of the umbilicus

Correct Answer & Explanation

. At the level of the greater trochanters

Explanation

Pelvic binders should be placed centered over the greater trochanters to effectively reduce the pelvic volume in open-book pelvic fractures. Placement over the iliac crests is less effective and may paradoxically open the pelvis further.

Question 387

Topic: Pelvic & Acetabular Trauma

Where is the optimal anatomical location to place a pelvic binder in a hemodynamically unstable patient with an anteroposterior compression pelvic ring injury?

. Over the iliac crests
. Over the greater trochanters
. Over the pubic symphysis
. Mid-thigh bilaterally
. Just superior to the umbilicus

Correct Answer & Explanation

. Over the greater trochanters

Explanation

Pelvic binders are most effective at reducing pelvic volume when centered directly over the greater trochanters. Placement over the iliac crests can paradoxically open the true pelvis further in some fracture patterns.

Question 388

Topic: Pelvic & Acetabular Trauma

A patient with a mechanically unstable pelvic ring injury remains hemodynamically unstable despite a pelvic binder and massive transfusion protocol. A FAST exam is negative. What is the most appropriate next step in management?

. Exploratory laparotomy
. Preperitoneal pelvic packing or angioembolization
. Intravenous tranexamic acid administration and observation
. Removal of the pelvic binder to assess for expansion
. CT scan of the abdomen and pelvis

Correct Answer & Explanation

. Preperitoneal pelvic packing or angioembolization

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, the source of bleeding is typically the retroperitoneal venous plexus or arterial branches. Preperitoneal pelvic packing and/or angioembolization are the treatments of choice.

Question 389

Topic: Pelvic & Acetabular Trauma
A 30-year-old trauma patient arrives with an anterior-posterior compression (APC-III) pelvic ring injury and is hemodynamically unstable. Where is the most biomechanically effective anatomical location to apply a noninvasive pelvic circumferential compression device (pelvic binder)?
. Iliac crests
. Level of the umbilicus
. Greater trochanters
. Anterior superior iliac spines
. Proximal femurs

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders are most effective at reducing pelvic volume and controlling hemorrhage when centered directly over the greater trochanters. Application higher up over the iliac crests or abdomen is less effective and can potentially worsen certain pelvic ring displacements.

Question 390

Topic: Pelvic & Acetabular Trauma

In long-segment fusions extending to the pelvis for adult degenerative scoliosis, Sacral-2 Alar-Iliac (S2AI) screws are often utilized instead of traditional iliac screws. Which of the following is an advantage of S2AI screws?

. They require a wider lateral fascial dissection
. They provide a starting point that is directly in-line with the lumbar pedicle screws
. They completely avoid crossing the sacroiliac (SI) joint
. They have a significantly higher rate of hardware prominence
. They require an offset connector for rod linkage

Correct Answer & Explanation

. They provide a starting point that is directly in-line with the lumbar pedicle screws

Explanation

S2AI screws have a starting point medial to traditional iliac screws, placing them directly in-line with the S1 and lumbar pedicle screws. This eliminates the need for bulky offset connectors, requires less lateral dissection, and significantly reduces hardware prominence.

Question 391

Topic: Pelvic & Acetabular Trauma

A 65-year-old man is evaluated for mild mid-back stiffness. Radiographs reveal flowing ossification along the anterolateral aspect of the thoracic vertebrae with preservation of disc height and no evidence of sacroiliac joint erosions. To meet the Resnick diagnostic criteria for Diffuse Idiopathic Skeletal Hyperostosis (DISH), this flowing ossification must bridge at least how many contiguous vertebral bodies?

. Two
. Three
. Four
. Five
. Six

Correct Answer & Explanation

. Four

Explanation

The diagnostic criteria for DISH established by Resnick include the presence of flowing ossification along the anterolateral aspect of at least four contiguous vertebral bodies, relative preservation of intervertebral disc height, and absence of apophyseal joint ankylosis or sacroiliac erosions.

Question 392

Topic: Pelvic & Acetabular Trauma

A 5-year-old female with residual acetabular dysplasia requires a pelvic osteotomy to improve anterolateral femoral head coverage. The surgeon plans an incomplete pericapsular osteotomy that hinges on the triradiate cartilage. Which procedure is being described?

. Salter innominate osteotomy
. Pemberton osteotomy
. Dega osteotomy
. Chiari osteotomy
. Shelf procedure

Correct Answer & Explanation

. Salter innominate osteotomy

Explanation

The Pemberton osteotomy is an incomplete pericapsular cut that hinges on the triradiate cartilage, effectively reducing acetabular volume and improving anterolateral coverage. In contrast, the Salter osteotomy hinges at the pubic symphysis.

Question 393

Topic: Pelvic & Acetabular Trauma

A 4-year-old child undergoes a Salter innominate osteotomy for the treatment of DDH. Which of the following biomechanical changes occurs as a direct result of this specific osteotomy?

. Medialization of the joint center
. Lateralization and distalization of the joint center
. Decreased anterior coverage
. Reduction in overall acetabular volume
. Hinging at the triradiate cartilage

Correct Answer & Explanation

. Medialization of the joint center

Explanation

The Salter osteotomy is a complete innominate cut that redirects the entire acetabulum to provide anterolateral coverage. Because it hinges at the pubic symphysis, it biomechanically lateralizes and distalizes the joint center, often lengthening the limb slightly.

Question 394

Topic: Pelvic & Acetabular Trauma

A 3-year-old girl is diagnosed with unilateral DDH. Closed reduction was unsuccessful. During an open reduction, an innominate osteotomy is planned to address acetabular dysplasia. Which of the following osteotomies hinges on the pubic symphysis to provide anterolateral coverage?

. Pemberton
. Dega
. Salter
. Chiari
. Shelf

Correct Answer & Explanation

. Pemberton

Explanation

The Salter innominate osteotomy involves a complete cut through the ilium and hinges on the pubic symphysis to redirect the acetabulum. This provides anterolateral coverage for the femoral head.

Question 395

Topic: Pelvic & Acetabular Trauma

A 25-year-old man presents with a posterior hip dislocation after a high-speed collision. Closed reduction under conscious sedation in the emergency department is unsuccessful. A CT scan demonstrates an empty acetabulum with no large bony fragments. What is the most likely soft-tissue structure blocking closed reduction?

. Iliopsoas tendon
. Ligamentum teres
. Piriformis muscle
. Rectus femoris
. Gluteus maximus

Correct Answer & Explanation

. Iliopsoas tendon

Explanation

In irreducible posterior hip dislocations, the femoral head can buttonhole through the posterior capsule and the short external rotators. The piriformis muscle, obturator internus, or the torn capsule itself are the most common structures preventing closed reduction.

Question 396

Topic: Pelvic & Acetabular Trauma

A 40-year-old male is involved in a high-speed motor vehicle collision and sustains an unstable vertical shear pelvic ring injury. Which of the following ligaments is the strongest and provides the most stability to the posterior pelvic ring?

. Anterior sacroiliac ligament
. Sacrospinous ligament
. Sacrotuberous ligament
. Posterior interosseous sacroiliac ligament
. Iliolumbar ligament

Correct Answer & Explanation

. Anterior sacroiliac ligament

Explanation

The posterior interosseous sacroiliac ligament is the thickest and strongest ligament in the pelvis. It serves as the primary restraint against vertical and anterior-posterior translation of the sacroiliac joint.

Question 397

Topic: Pelvic & Acetabular Trauma

When placing iliosacral screws for pelvic ring injuries, the surgeon must remain within the osseous safe zone of the sacral ala. The anterior limit of this safe zone in S1 is defined by the risk of injury to which structure?

. L4 nerve root
. L5 nerve root
. S1 nerve root
. Internal iliac artery
. Sympathetic chain

Correct Answer & Explanation

. L4 nerve root

Explanation

The L5 nerve root runs directly anterior to the sacral ala. Breaching the anterior cortex of the S1 body or ala places the L5 nerve root at significant risk of iatrogenic injury.

Question 398

Topic: Pelvic & Acetabular Trauma

A 5-year-old child with residual developmental dysplasia of the hip undergoes a Pemberton osteotomy. Unlike a Salter osteotomy, the Pemberton osteotomy hinges on which of the following anatomic structures to achieve acetabular redirection?

. Pubic symphysis
. Sacroiliac joint
. Triradiate cartilage
. Ischial tuberosity
. Greater sciatic notch

Correct Answer & Explanation

. Pubic symphysis

Explanation

The Pemberton osteotomy is an incomplete pericapsular osteotomy that hinges on the flexible triradiate cartilage in children. In contrast, the Salter osteotomy is a complete innominate osteotomy that hinges on the pubic symphysis.

Question 399

Topic: Pelvic & Acetabular Trauma

A 3-year-old girl presents with a painless waddling gait. Radiographs show a completely dislocated left hip with a false acetabulum and a dysplastic true acetabulum. She has had no prior treatment. What is the most appropriate surgical management?

. Closed reduction and spica casting
. Arthroscopic labral repair and capsulorrhaphy
. Open reduction alone
. Femoral varus derotational osteotomy alone
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy

Correct Answer & Explanation

. Closed reduction and spica casting

Explanation

In children over 2 to 3 years of age with an untreated completely dislocated hip, the soft tissues are contracted and the acetabulum is dysplastic. Successful management typically requires an open reduction, a femoral shortening osteotomy (to relieve tension and prevent AVN), and a pelvic osteotomy (e.g., Salter or Dega) to provide anterior/lateral coverage.

Question 400

Topic: Pelvic & Acetabular Trauma

Which pelvic osteotomy for DDH provides primarily anterior and lateral coverage by hinging on the pubic symphysis without changing the shape of the acetabulum?

. Pemberton osteotomy
. Dega osteotomy
. Salter osteotomy
. Chiari osteotomy
. Shelf arthroplasty

Correct Answer & Explanation

. Pemberton osteotomy

Explanation

The Salter innominate osteotomy is a redirectional osteotomy that hinges at the pubic symphysis. It improves anterior and lateral coverage without altering the volume or shape of the acetabulum.

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