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Pelvic & Acetabular Trauma MCQs

Practice Set 1 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 1

Topic: Pelvic & Acetabular Trauma

An elite runner presents with chronic groin pain exacerbated by kicking and sprinting. Radiographs show symphyseal sclerosis and widening. What is the most reliable diagnostic injection to confirm osteitis pubis as the primary pain generator?

. Ilioinguinal nerve block
. Psoas bursa injection
. Intra-articular hip injection
. Pubic symphysis cleft injection
. Obturator nerve block

Correct Answer & Explanation

. Pubic symphysis cleft injection

Explanation

A targeted fluoroscopic or ultrasound-guided injection of local anesthetic into the pubic symphysis is the most reliable way to confirm osteitis pubis. It differentiates this condition from intra-articular hip pathology or athletic pubalgia.

Question 2

Topic: Pelvic & Acetabular Trauma
A rugby player presents 1 week after a severe tangential blow to the lateral thigh with a large, fluctuant mass over the greater trochanter. What is the primary pathophysiology of this Morel-Lavallée lesion?
. Intramuscular hematoma confined by the fascia lata
. Post-traumatic synovial cyst of the trochanteric bursa
. Separation of the subcutaneous tissue from the underlying fascia, filling with hemolymph
. Avulsion of the gluteus medius with seroma formation
. Rupture of the vastus lateralis with muscle herniation

Correct Answer & Explanation

. Separation of the subcutaneous tissue from the underlying fascia, filling with hemolymph

Explanation

A Morel-Lavallée lesion is a closed degloving injury where a shearing force separates the skin and subcutaneous tissue from the underlying investing fascia. The resulting potential space fills with blood, lymph, and necrotic fat.

Question 3

Topic: Pelvic & Acetabular Trauma

A professional water skier sustains a forced hyperabduction injury to his hip, resulting in acute medial groin pain. Examination reveals an ecchymotic mass in the medial thigh and weakness in hip adduction. What is the most common site of injury in this scenario?

. Myotendinous junction of the adductor magnus
. Proximal origin of the adductor longus
. Distal insertion of the adductor longus
. Mid-substance tear of the gracilis
. Avulsion of the pectineus from the pubic ramus

Correct Answer & Explanation

. Proximal origin of the adductor longus

Explanation

Acute injuries to the adductor muscle group most frequently involve the adductor longus. Ruptures typically occur at its proximal origin near the pubic symphysis, often treated nonoperatively, though surgery may be considered for elite athletes with significant retraction.

Question 4

Topic: Pelvic & Acetabular Trauma

A 28-year-old male distance runner complains of insidious onset anterior pelvic pain that radiates to the lower abdomen and bilateral groins. Radiographs reveal subchondral sclerosis, cystic changes, and widening of the pubic symphysis. What is the most appropriate initial treatment?

. Platelet-rich plasma (PRP) injection into the symphysis
. Wide excision of the pubic symphysis
. Pubic symphyseal arthrodesis
. Rest, NSAIDs, and physical therapy focused on core stabilization
. Bilateral adductor tenotomy

Correct Answer & Explanation

. Rest, NSAIDs, and physical therapy focused on core stabilization

Explanation

Osteitis pubis is an overuse inflammatory condition of the pubic symphysis. The cornerstone of initial management is conservative, including rest, nonsteroidal anti-inflammatory drugs (NSAIDs), and physical therapy aimed at core and pelvic stabilization.

Question 5

Topic: Pelvic & Acetabular Trauma

A 26-year-old professional soccer player presents with chronic, gradually worsening anterior pelvic pain. Examination shows point tenderness directly over the pubic symphysis. Radiographs reveal sclerosis and widening of the symphysis pubis. What is the most appropriate initial treatment?

. Surgical debridement and symphyseal arthrodesis
. Core muscle repair
. Rest and NSAIDs
. Corticosteroid injection into the rectus abdominis
. Bilateral adductor tenotomy

Correct Answer & Explanation

. Rest and NSAIDs

Explanation

Osteitis pubis is a painful, non-infectious inflammatory condition characterized by sclerosis and widening of the pubic symphysis. The initial treatment is always non-operative, focusing on rest, NSAIDs, and progressive physical therapy.

Question 6

Topic: Pelvic & Acetabular Trauma

A 35-year-old male sustains an anteroposterior compression (APC) type II pelvic ring injury. Based on the Young-Burgess classification, which of the following accurately describes the status of the sacroiliac (SI) ligaments?

. Anterior and posterior SI ligaments are intact
. Anterior SI ligaments are disrupted, posterior SI ligaments are intact
. Anterior and posterior SI ligaments are disrupted
. Posterior SI ligaments are disrupted, anterior SI ligaments are intact
. Sacrotuberous ligaments are disrupted, SI ligaments are intact

Correct Answer & Explanation

. Anterior SI ligaments are disrupted, posterior SI ligaments are intact

Explanation

In an APC II pelvic ring injury, there is symphyseal diastasis and disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. The strong posterior sacroiliac ligaments remain intact, maintaining vertical stability.

Question 7

Topic: Pelvic & Acetabular Trauma

Which of the following descriptions applies to the sacroiliac joint:

. The sacroiliac joint accounts for 15% of lower back pain.
. Pain is referred most commonly to the groin.
. Focal pain over the sacral sulcus is rare.
. Focal neurological deficits are common.
. Provocative tests (Patrick and Gaenslens) are useful predictors of joint pathology.

Correct Answer & Explanation

. The sacroiliac joint accounts for 15% of lower back pain.

Explanation

Sacroiliac joint pathology accounts for 15% of lower back pain, and the sacroiliac joint is one of the most common sites of referred pain. Patients with sacroiliac joint pathology commonly experience pain above the posterior buttock and seldom have focal neurological deficits. Physical examination tests are poor predictors of sacroiliac joint pathology.

Question 8

Topic: Pelvic & Acetabular Trauma

Which of the following statements is true regarding the sacroiliac joint:

. The anterior supporting structures are stronger than the posterior supporting structures.
. Sectioning of the sacrotuberous and sacrospinous ligaments results in increased motion.
. The sacroiliac joint withstands medially directed forces better than the lumbosacral spine.
. C ounter-nutation (forward rotation of the ilium on the sacrum) is the most common motion.
. The posterior interosseous ligaments are weak.

Correct Answer & Explanation

. Sectioning of the sacrotuberous and sacrospinous ligaments results in increased motion.

Explanation

The sacroiliac joint is the largest axial joint in the body. The anterior capsule is thin and weaker than the posterior capsule. The posterior supporting structures are strong and are comprised of a tough interosseous ligament, a long posterior sacroiliac ligament, and strong sacrotuberous, sacrospinous ligaments. Joint innervation usually occurs anteriorly in the S2 ventral rami. Compared with the lumbosacral spine, the sacroiliac joint can better withstand medial forces, but is weaker in axial compression and in axial torsion. Nutation (backward rotation of less than 4° and 1.6 mm rotation of the ilium on the sacrum) is the most common motion in the sacroiliac joint. Increased motion of the sacroiliac joint occurs only with sectioning of the interosseous ligaments.

Question 9

Topic: Pelvic & Acetabular Trauma

During multi-level posterior spinal fusion for degenerative scoliosis, Smith-Petersen Osteotomies (SPOs) are performed. Which spinal column(s) is/are shortened and lengthened during an SPO?

. Shortens posterior column, lengthens anterior column
. Shortens both posterior and middle columns
. Shortens anterior column, lengthens posterior column
. Shortens all three columns
. Lengthens middle column, shortens anterior column

Correct Answer & Explanation

. Shortens posterior column, lengthens anterior column

Explanation

A Smith-Petersen Osteotomy (SPO) involves resection of the posterior ligaments and facet joints. Upon closure, it shortens the posterior column and lengthens the anterior column by hinging on the posterior annulus/ligamentum flavum.

Question 10

Topic: Pelvic & Acetabular Trauma

In a healthy, sagittally balanced adult, the C7 plumb line should fall within what structure on a standing lateral radiograph?

. Anterior to the pubic symphysis
. Through the center of the femoral heads
. Posterior to the posterior margin of the sacrum
. Within 2 cm of the posterosuperior corner of S1
. Anterior to the L5 vertebral body

Correct Answer & Explanation

. Within 2 cm of the posterosuperior corner of S1

Explanation

The normal Sagittal Vertical Axis (SVA), measured by dropping a plumb line from the center of the C7 vertebral body, should pass within +/- 2 cm of the posterior superior corner of the S1 endplate.

Question 11

Topic: Pelvic & Acetabular Trauma

When performing a long fusion to the sacrum for adult deformity, S2-alar-iliac (S2AI) screws are commonly used. What is the primary biomechanical and technical advantage of S2AI screws compared to traditional iliac screws?

. They bypass the sacroiliac joint completely
. They provide a significantly higher pull-out strength
. They are in-line with the lumbar pedicle screws requiring less rod contouring
. They require a separate fascial incision to place
. They avoid penetration of the iliac cortical bone

Correct Answer & Explanation

. They are in-line with the lumbar pedicle screws requiring less rod contouring

Explanation

The primary advantage of S2AI screws is that their starting point is in-line with the S1 and lumbar pedicle screws, minimizing the need for complex rod contouring or bulky offset connectors.

Question 12

Topic: Pelvic & Acetabular Trauma

Diffuse Idiopathic Skeletal Hyperostosis (DISH) is characterized radiographically by flowing ossification along the anterolateral aspect of the vertebral bodies. By Resnick criteria, this flowing ossification must involve at least how many contiguous vertebral bodies?

. Two
. Three
. Four
. Five
. Six

Correct Answer & Explanation

. Four

Explanation

The Resnick and Niwayama radiographic criteria for DISH require the presence of flowing ossification along the anterolateral aspect of at least four contiguous vertebral bodies. It also requires the relative preservation of disc height and absence of sacroiliac joint fusion.

Question 13

Topic: Pelvic & Acetabular Trauma

The following nonoperative treatments have not been proven effective in the early acute stage (2 weeks to 3 months) of low back pain:

. Nonsteroidal anti-inflammatory drugs
. Bed rest
. Anesthetic/corticosteriod injections into the epidural space
. Intrathecal anesthetic/corticosteriod injections
. Intraspinal anesthetic/corticosteriod injections

Correct Answer & Explanation

. Intraspinal anesthetic/corticosteriod injections

Explanation

Nonsteroidal anti-inflammatory drugs have been shown effective and are frequently used during the acute phase of low back pain. Their main effect is to alleviate soft tissue inflammation that is often present in the early phase. Patient questionnaires have identified bed rest as among the most frequently prescribed treatments for lower back pain. It has been shown that bed rest results in reduced intradiskal pressure that occurs in the supine position. Anesthetic/corticosteriod injections are widely advocated for the treatment of low back pain and can be administered along nerve roots, into the sacroiliac joints, intervertebral disks, paraspinal soft tissues, and the epidural space or intrathecally for many conditions. However, there is no evidence that intraspinal steroids have an effective role in the acute management of low back pain.

Question 14

Topic: Pelvic & Acetabular Trauma



Which of the following statements regarding the pelvic anatomy in patients with classic bladder exstrophy is correct?

. The pubic symphysis is closed but dysplastic
. There is internal rotation of the posterior ilium
. The acetabulum is retroverted
. The pubic rami are internally rotated
. The sacrum is typically completely absent

Correct Answer & Explanation

. The acetabulum is retroverted

Explanation

In classic bladder exstrophy, the anterior pelvic ring is open. The bony pelvis is characterized by external rotation of the posterior ilium, external rotation of the pubic rami, and profound retroversion of the acetabulum, leading to an out-toeing gait.

Question 15

Topic: Pelvic & Acetabular Trauma

Which of the following iliac osteotomies provides the greatest freedom of mobilization of the acetabular segment:

. Salter osteotomy
. Pemberton osteotomy
. Steel osteotomy
. Chiari osteotomy
. Ganz osteotomy

Correct Answer & Explanation

. Ganz osteotomy

Explanation

Osteotomies that are made closest to the acetabulum provide the greatest freedom of mobilization. Of the choices provided, the Ganz or Bernese osteotomy is made closest to the acetabulum.

Question 16

Topic: Pelvic & Acetabular Trauma

The acetabular sourcil is best described as:

. The lateral articular border
. The teardrop
. The acetabular angle
. A degenerative osteophyte
. A cyst forming in hip dysplasia

Correct Answer & Explanation

. The lateral articular border

Explanation

The acetabular sourcil is a lateral articular border, which normally should be downsloping and below the dome of the acetabulum. In dysplastic hips, the femoral head pushes the acetabular sourcil up and gives it an upsloping shape.

Question 17

Topic: Pelvic & Acetabular Trauma

A 15-year-old girl has anterior hip pain and she tells you that she hears periodic snapping or clicking. Bringing the hip from the flexed-abducted position to the extended position reproduces the pain. Radiographs are normal. The diagnosis is most likely:

. Trochanteric bursitis
. Acetabular dysplasia
. Snapping psoas tendon
. Torn acetabular labrum
. Femoral hernia

Correct Answer & Explanation

. Snapping psoas tendon

Explanation

Snapping of the psoas tendon is more common in girls than boys. A snapped psoas tendon is characterized by anterior hip pain that can be reproduced by moving the hip from a figure 4 position to an extended position. The discomfort from trochanteric bursitis is located laterally. The symptoms of an abnormality in the labrum or the acetabulum are not associated with snapping.

Question 18

Topic: Pelvic & Acetabular Trauma

A 4-year-old girl is newly diagnosed with developmental dislocations of the hips. The femoral heads are fully dislocated and located 4 cm above the acetabulum. No pseudoacetabulum is seen. Recommended treatment includes:

. No treatment
. Traction and closed reduction
. Open reduction through a medial approach
. C losed reduction and Salter osteotomy
. Open reduction through an anterolateral approach with femoral and iliac osteotomies

Correct Answer & Explanation

. Open reduction through an anterolateral approach with femoral and iliac osteotomies

Explanation

At the age of 4, femoral shortening is indicated to remove the pressure on the reduced femoral head. Realignment of the bony dysplasia is achieved by femoral derotation, iliac redirection, and possible creation of varus in the proximal femur. Open reduction through a medial approach is an option during the first 2 years, but after that the anterolateral approach is preferred in order to create a stable capsulorrhaphy.

Question 19

Topic: Pelvic & Acetabular Trauma

A 40-year-old man is involved in a high-speed motor vehicle collision. Pelvic radiographs show an anteroposterior compression (APC) Type II injury, with widening of the pubic symphysis of 3.5 cm and widening of the anterior sacroiliac joints. Which ligaments are classically disrupted in this specific injury pattern?

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments
. Posterior sacroiliac and iliolumbar ligaments
. Anterior and posterior sacroiliac ligaments
. Sacrospinous ligament only
. Inguinal and lacunar ligaments

Correct Answer & Explanation

. Anterior sacroiliac, sacrotuberous, and sacrospinous ligaments

Explanation

In an APC II pelvic ring injury, there is disruption of the symphysis pubis, the anterior sacroiliac ligaments, and the pelvic floor ligaments (sacrotuberous and sacrospinous). The posterior sacroiliac ligaments remain intact, providing vertical stability.

Question 20

Topic: Pelvic & Acetabular Trauma
A 28-year-old man is brought in after a high-speed motor vehicle collision. He is hypotensive (BP 80/40 mmHg) and tachycardic. Pelvic radiographs show an anteroposterior compression (APC) type III injury with completely disrupted sacroiliac joints bilaterally. A pelvic binder has been applied. FAST exam is negative. What is the most appropriate next step to manage his hemodynamics?
. CT abdomen and pelvis with IV contrast
. Exploratory laparotomy
. Preperitoneal pelvic packing or angioembolization
. Application of an external fixator in the emergency department
. Administration of tranexamic acid and wait for response

Correct Answer & Explanation

. Preperitoneal pelvic packing or angioembolization

Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury and a negative FAST exam, the bleeding is likely retroperitoneal. Preperitoneal pelvic packing or pelvic angiography with embolization are the appropriate emergent interventions to control venous and arterial hemorrhage.

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