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Pelvic & Acetabular Trauma MCQs

Practice Set 27 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 521

Topic: Pelvic & Acetabular Trauma

  • Which of the following medicolegal relationships between an attending surgeon and a resident assistant applies when a patient files a malpractice suit relating to surgical complications following a total knee arthroplasty?
. Respondeat superior
. Indemnity agreement
. Hold harmless agreement- attempt to shift liability from company to physician
. Comparative negligence-% of involvement
. Contributory negligence- resident contributed to the negligence
. t-type
. both column
. transverse
. anterior column
. anterior column posterior hemitransverse
. Posterior interosseous
. Anterior interosseous
. Radial
. Median
. Ulnar
. Shock from hypovolemia
. Associated rupture of the bladder
. Arterial bleeding on pelvic angiogram
. Presence of a hematoma in the perineum and scrotum
. Fractures of both the anterior and posterior pelvic ring

Correct Answer & Explanation

. Respondeat superior

Explanation

Question 522

Topic: Pelvic & Acetabular Trauma
A 38-year-old male is brought to the trauma bay after a motorcycle collision. He has a heart rate of 130 bpm and blood pressure of 75/40 mmHg. Pelvic radiographs show an anteroposterior compression type III (APC III) injury. After initiating massive transfusion protocols, what is the most appropriate initial mechanical intervention?
. Immediate open reduction and internal fixation of the pubic symphysis
. Application of a pelvic binder centered over the iliac crests
. Application of a pelvic binder centered over the greater trochanters
. Bilateral internal iliac artery embolization
. Placement of a resuscitative endovascular balloon occlusion of the aorta (REBOA)

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 mechanical intervention is the application of a pelvic binder to reduce pelvic volume and promote tamponade. The binder must be centered over the greater trochanters, not the iliac crests, to effectively close the pelvic ring.

Question 523

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the ED after a motorcycle crash. Pelvic radiographs show an APC-III pelvic ring injury. He remains hemodynamically unstable despite a pelvic binder and massive transfusion protocols. What is the most appropriate next step in surgical management?
. Bilateral internal iliac artery embolization
. Exploratory laparotomy
. Preperitoneal pelvic packing
. Application of a supra-acetabular external fixator
. Sacroiliac screw fixation

Correct Answer & Explanation

. Preperitoneal pelvic packing

Explanation

In a hemodynamically unstable patient with a mechanically stabilized pelvic ring injury, preperitoneal pelvic packing or angioembolization is indicated. Hemorrhage in APC injuries is most commonly venous from the presacral plexus, making packing highly effective.

Question 524

Topic: Pelvic & Acetabular Trauma
A 40-year-old hypotensive male presents with an anteroposterior compression type III (APC-III) pelvic ring injury. To be most effective in reducing pelvic volume and venous bleeding, a pelvic binder must be centered directly over which anatomic landmarks?
. Iliac crests
. Anterior superior iliac spines
. Greater trochanters
. Pubic symphysis
. L5-S1 junction

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders provide the most effective mechanical reduction of pelvic volume when centered directly over the greater trochanters. Placing them higher (e.g., over the iliac crests) is less effective and may exacerbate the injury.

Question 525

Topic: Pelvic & Acetabular Trauma

In a patient who sustains a highly unstable vertical shear or an anteroposterior compression (APC) pelvic ring fracture with severe posterior sacroiliac (SI) joint disruption, massive retroperitoneal hemorrhage is often encountered. When arterial bleeding is the primary source in the setting of a posterior ring injury, which artery is most frequently implicated?

. Obturator artery
. Superior gluteal artery
. Internal pudendal artery
. External iliac artery
. Inferior epigastric artery

Correct Answer & Explanation

. Superior gluteal artery

Explanation

While the majority of pelvic hemorrhage is venous (from the presacral venous plexus) or from cancellous bone surfaces, arterial hemorrhage can be life-threatening. In posterior pelvic ring injuries (SI joint disruptions and sacral fractures), the superior gluteal artery is the most commonly injured artery as it exits the pelvis through the greater sciatic notch in close proximity to the SI joint.

Question 526

Topic: Pelvic & Acetabular Trauma
During the acute resuscitation of a hemodynamically unstable patient with an anteroposterior compression (APC) type III pelvic ring injury, a pelvic binder is applied. To optimally reduce pelvic volume and control venous hemorrhage, the binder should be centered directly over which of the following anatomic landmarks?
. The anterior superior iliac spines (ASIS)
. The iliac crests
. The greater trochanters
. The pubic symphysis
. The level of the umbilicus

Correct Answer & Explanation

. The greater trochanters

Explanation

Pelvic binders must be placed accurately at the level of the greater trochanters to effectively close the pelvic ring, internally rotate the hemipelvises, and maximally reduce pelvic volume. Placement higher up over the ASIS or iliac crests is less effective and can paradoxically open the pelvic ring further in certain fracture patterns.

Question 527

Topic: Pelvic & Acetabular Trauma
You are applying a commercial pelvic binder to a hemodynamically unstable patient with an APC-III open-book pelvic ring injury. For maximum biomechanical efficacy and optimal reduction of pelvic volume, the binder should be centered over which anatomical landmarks?
. Iliac crests
. Greater trochanters
. Anterior superior iliac spines
. Pubic symphysis
. Sacral promontory

Correct Answer & Explanation

. Greater trochanters

Explanation

Pelvic binders are most effective at reducing pelvic volume and controlling life-threatening retroperitoneal hemorrhage when placed precisely at the level of the greater trochanters. Improper placement higher over the iliac crests is biomechanically inferior and frequently restricts critical abdominal access.

Question 528

Topic: Pelvic & Acetabular Trauma
An anteroposterior compression type III (APC III) pelvic ring injury is characterized by complete disruption of the symphysis pubis and which of the following posterior structures?
. Anterior sacroiliac ligaments only
. Sacrotuberous and sacrospinous ligaments only
. Anterior and posterior sacroiliac ligaments
. Iliolumbar ligament only
. Lumbosacral plexus

Correct Answer & Explanation

. Anterior and posterior sacroiliac ligaments

Explanation

An APC III injury involves a complete disruption of both the anterior and posterior sacroiliac ligaments, along with the sacrotuberous and sacrospinous ligaments. This extensive damage results in complete global instability of the hemipelvis.

Question 529

Topic: Pelvic & Acetabular Trauma
A 28-year-old male sustains an anteroposterior compression type III (APC-III) pelvic ring injury. Initial resuscitation includes a pelvic binder. Where is the most appropriate anatomical location to center the pelvic binder to effectively reduce pelvic volume?
. Over the iliac crests
. Over the anterior superior iliac spines (ASIS)
. Directly over the greater trochanters
. Over the umbilicus
. At the level of the ischial tuberosities

Correct Answer & Explanation

. Directly over the greater trochanters

Explanation

A pelvic binder should be centered directly over the greater trochanters to effectively close the pelvic ring and reduce volume. Placement higher, such as over the iliac crests or ASIS, is less effective and can paradoxically exacerbate the deformity.

Question 530

Topic: Pelvic & Acetabular Trauma

In the acute management of a hemodynamically unstable patient with an anteroposterior compression (APC) pelvic ring injury, what is the anatomically correct placement level for a circumferential pelvic binder?

. Anterior superior iliac spines
. Anterior inferior iliac spines
. Greater trochanters
. Iliac crests
. Pubic symphysis strictly

Correct Answer & Explanation

. Anterior superior iliac spines

Explanation

Pelvic binders must be centered over the greater trochanters to effectively reduce the pelvic volume and stabilize the fracture. Placement over the iliac crests or ASIS can paradoxically open the pelvic ring.

Question 531

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable patient with an anteroposterior compression type III (APC III) pelvic ring injury is brought to the trauma bay. A pelvic binder is applied. What is the next most appropriate orthopedic intervention if the patient remains persistently hypotensive despite fluid resuscitation?
. Application of an external fixator
. Retrograde urethrogram
. Preperitoneal pelvic packing
. Open reduction internal fixation of the symphysis
. Emergent bilateral internal iliac artery embolization

Correct Answer & Explanation

. Preperitoneal pelvic packing

Explanation

Preperitoneal pelvic packing (PPP) or pelvic angiography are the appropriate next steps for persistent hemodynamic instability. PPP is increasingly favored for rapid control of venous bleeding, which is the most common source of pelvic hemorrhage.

Question 532

Topic: Pelvic & Acetabular Trauma
During single-leg stance, the hip abductor muscles must generate sufficient force to maintain a level pelvis. In a normal adult hip, the ratio of the body weight moment arm to the abductor moment arm is approximately 2.5 to 1. If a patient weighs 800 N, what is the approximate joint reaction force across the hip during single-leg stance?
. 800 N
. 1200 N
. 2000 N
. 2800 N
. 4000 N

Correct Answer & Explanation

. 2800 N

Explanation

To maintain a level pelvis in single-leg stance, the torque generated by the abductors must equal the torque of the body weight. Given the moment arm ratio is 2.5:1, Abductor Force ร— 1 = Body Weight ร— 2.5. Therefore, Abductor Force = 800 N ร— 2.5 = 2000 N. The total joint reaction force (JRF) across the hip is the sum of the body weight and the abductor force pulling the femur into the acetabulum. JRF = 800 N + 2000 N = 2800 N (which is 3.5 times body weight).

Question 533

Topic: Pelvic & Acetabular Trauma
In patients with Crowe types III and IV developmental dysplasia of the hip with high hip centers, acetabular reconstruction often requires lowering the acetabular component into the native acetabulum. In doing so, significant risk for limb lengthening beyond 4 cm exists, making the hip difficult to reduce and also raising risk for nerve injury. Which technique is used to overcome this problem?
. Subtrochanteric osteotomy with femoral shortening
. Use of an offset femoral component
. Use of a lateralized liner
. Extended trochanteric osteotomy

Correct Answer & Explanation

. Subtrochanteric osteotomy with femoral shortening

Explanation

When significant lengthening of a dysplastic hip will occur because a high dislocation is relocated into a significantly lower acetabulum, a femoral shortening may be necessary to reduce the hip and avoid a stretch injury to the sciatic nerve. No other choice specifically addresses the need for femoral shortening, and high offset stems and lateralized liners may exacerbate the problem if used alone and without femoral shortening.

Question 534

Topic: Pelvic & Acetabular Trauma
A 38-year-old female pedestrian is struck by a vehicle. She arrives hypotensive (BP 75/40 mmHg) with a mechanically unstable pelvis. An anterior-posterior compression (APC) type III injury is suspected. A pelvic binder is to be applied. What is the optimal anatomic landmark to center the pelvic binder to maximize reduction of the pelvic volume?
. The iliac crests
. The anterior superior iliac spines (ASIS)
. The greater trochanters
. The pubic symphysis
. The level of the umbilicus

Correct Answer & Explanation

. The greater trochanters

Explanation

For emergency stabilization of a mechanically unstable, open-book type pelvic ring injury (APC II/III), a pelvic binder or sheet should be centered over the greater trochanters. Placing the binder over the greater trochanters effectively provides an inward force vector that closes the anterior pelvic ring and reduces pelvic volume, aiding in hemorrhage control. Placement over the iliac crests is less effective and may paradoxically widen the true pelvis.

Question 535

Topic: Pelvic & Acetabular Trauma
A 28-year-old female presents with a closed pelvic ring fracture after being run over by a truck. Examination reveals a large, fluctuant swelling over the greater trochanter with overlying skin bruising and reduced sensation. Which of the following best describes the pathophysiology of this soft tissue injury?
. Direct crush injury leading to rhabdomyolysis of the gluteal musculature
. Shearing force separating the subcutaneous tissue from the underlying fascia, disrupting perforating vessels
. Arterial bleeding from a torn superficial femoral artery expanding into the subcutaneous space
. Lymphatic fluid accumulation due to disruption of inguinal lymph nodes
. Herniation of muscle tissue through a traumatic fascial defect

Correct Answer & Explanation

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

Explanation

This is a Morel-Lavallรฉe lesion, caused by a closed degloving or shearing injury. It results in the separation of skin and subcutaneous fat from the underlying fascial layer, disrupting perforating vessels and causing a hemolymphatic collection.

Question 536

Topic: Pelvic & Acetabular Trauma

A 38-year-old pedestrian is struck by a vehicle, sustaining an anterior-posterior compression (APC) type II pelvic ring injury. Which of the following best describes the ligamentous disruption pattern in this specific injury?

. Disruption of the symphysis pubis only, with intact anterior and posterior sacroiliac ligaments
. Disruption of the symphysis pubis, anterior sacroiliac ligaments, and sacrospinous/sacrotuberous ligaments, with intact posterior sacroiliac ligaments
. Complete disruption of the symphysis pubis, anterior, and posterior sacroiliac ligaments
. Disruption of the posterior sacroiliac ligaments with an intact symphysis pubis
. Avulsion of the sacrotuberous ligament with intact anterior sacroiliac ligaments

Correct Answer & Explanation

. Disruption of the symphysis pubis only, with intact anterior and posterior sacroiliac ligaments

Explanation

An APC II injury involves widening of the symphysis pubis >2.5 cm, tearing of the anterior sacroiliac, sacrospinous, and sacrotuberous ligaments. The posterior sacroiliac ligaments remain intact, providing vertical stability.

Question 537

Topic: Pelvic & Acetabular Trauma
A 28-year-old hypotensive male is brought in after a motorcycle crash. A pelvic binder is immediately applied. Radiographs show a widened symphysis pubis and disrupted sacroiliac joints bilaterally, consistent with an Anteroposterior Compression (APC) Type III injury. FAST scan is negative. Despite 2 units of uncrossmatched blood and crystalloid resuscitation, his blood pressure remains 75/40 mmHg. What is the most appropriate next step in management?
. Exploratory laparotomy
. Pelvic angiography and embolization
. Immediate open reduction and internal fixation of the anterior pelvic ring
. Zone III REBOA placement followed by definitive internal fixation
. Application of a supra-acetabular external fixator and transfer to the ICU

Correct Answer & Explanation

. Pelvic angiography and embolization

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and no other identified source of major bleeding (negative FAST and chest X-ray), pelvic angiography and embolization is indicated to control arterial hemorrhage. The bleeding is typically from branches of the internal iliac artery, such as the superior gluteal, internal pudendal, or obturator arteries.

Question 538

Topic: Pelvic & Acetabular Trauma
A 28-year-old female is brought to the ED after a motor vehicle collision. She is hemodynamically unstable. A pelvic binder is applied. Radiographs show a widened symphysis pubis > 2.5 cm and disruption of the anterior sacroiliac ligaments, but intact posterior sacroiliac ligaments. According to the Young-Burgess classification, what type of injury is this, and what is the most common primary source of bleeding?
. APC I, venous plexus
. APC II, venous plexus
. APC III, arterial (superior gluteal artery)
. LC I, arterial (obturator artery)
. VS, venous plexus

Correct Answer & Explanation

. APC II, venous plexus

Explanation

Anterior Posterior Compression (APC) II injuries involve symphyseal widening > 2.5 cm with disruption of the anterior SI ligaments, sacrotuberous, and sacrospinous ligaments, but the posterior SI ligaments remain intact, providing vertical stability but rotational instability. The primary source of life-threatening hemorrhage in pelvic fractures, especially open book types, is the presacral venous plexus, though arterial bleeding can also occur.

Question 539

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable 35-year-old male with an APC-III pelvic ring injury remains hypotensive (BP 70/40 mmHg) despite pelvic binder application, activation of a massive transfusion protocol, and a negative FAST exam. What is the most appropriate next step in acute management?
. CT angiography to localize specific arterial bleeding
. Emergent exploratory laparotomy
. Preperitoneal pelvic packing or pelvic angiography with embolization
. Application of an external fixator to replace the pelvic binder
. Diagnostic peritoneal lavage (DPL)

Correct Answer & Explanation

. Preperitoneal pelvic packing or pelvic angiography with embolization

Explanation

In a hemodynamically unstable pelvic fracture with a negative FAST (ruling out major intra-abdominal hemorrhage), the bleeding is presumed pelvic. Immediate preperitoneal packing or angiography with embolization is indicated to control retroperitoneal hemorrhage.

Question 540

Topic: Pelvic & Acetabular Trauma
A hemodynamically unstable patient with an anterior-posterior compression (APC-III) pelvic ring injury requires emergent pelvic binder application. What is the correct anatomical landmark for positioning the binder?
. Over the iliac crests
. Over the greater trochanters
. At the level of the umbilicus
. Mid-thigh
. Over the lower lumbar spine

Correct Answer & Explanation

. Over the greater trochanters

Explanation

Pelvic binders must be centered directly over the greater trochanters to effectively close the pelvic volume and provide tamponade. Placing it over the iliac crests is less effective and may worsen the deformity.

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