Menu

2. Trauma MCQs

Practice Set 627 of 640

This practice set contains high-yield board review questions covering key concepts in 2. Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 12521

Topic: Pelvic & Acetabular Trauma

Which of the following is considered an unstable pelvic ring injury according to the Young-Burgess classification?

. Lateral Compression Type I (LC-I)
. Anterior-Posterior Compression Type I (APC-I)
. Lateral Compression Type II (LC-II)
. Vertical Shear (VS)
. Anterior-Posterior Compression Type II (APC-II)

Correct Answer & Explanation

. Vertical Shear (VS)

Explanation

According to the Young-Burgess classification, Vertical Shear (VS) injuries are inherently unstable. They involve complete disruption of the posterior pelvic ring (sacroiliac joint or sacral fractures) and often the anterior ring as well, with vertical displacement. LC-I, APC-I, and APC-II are generally considered stable or rotationally unstable but vertically stable (APC-II has partial posterior disruption). LC-II involves posterior ligamentous disruption (sacrotuberous and sacrospinous ligaments) but the posterior arch may remain intact, making it rotationally unstable but not necessarily vertically unstable without further disruption.

Question 12522

Topic: 2. Trauma

A 68-year-old female undergoes cemented total hip arthroplasty. Intraoperatively, during reaming of the acetabulum, she develops hypotension, hypoxia, and a sudden drop in end-tidal CO2. What is the most likely cause of these acute physiological changes?

. Anaphylactic reaction to cement.
. Periprosthetic fracture.
. Fat embolism syndrome.
. Cardiac arrest.
. Pulmonary embolism.

Correct Answer & Explanation

. Fat embolism syndrome.

Explanation

The described intraoperative triad of hypotension, hypoxia, and a sudden drop in end-tidal CO2 during total hip arthroplasty, especially during reaming or cementing, is highly suggestive of Fat Embolism Syndrome (FES). Bone marrow fat emboli can enter the circulation, leading to pulmonary and systemic effects. While a pulmonary embolism could cause similar symptoms, the acute onset during specific surgical maneuvers points more to FES. Anaphylaxis would typically involve rash, bronchospasm, and more severe cardiovascular collapse. Periprosthetic fracture is a mechanical complication, not a systemic physiological event. Cardiac arrest is the end result, not the primary cause of these specific changes.

Question 12523

Topic: 2. Trauma

Which biomechanical principle explains the benefit of using an intramedullary nail over a plate for load-sharing in diaphyseal long bone fractures?

. Tension band principle.
. Wolff's Law.
. Stress shielding.
. Load sharing.
. Strain hardening.

Correct Answer & Explanation

. Load sharing.

Explanation

Intramedullary nails are considered load-sharing devices because they are placed within the medullary canal, closer to the mechanical axis of the bone. This allows the bone to continue to bear a significant portion of the physiological load, which promotes secondary bone healing (callus formation). Plates, on the other hand, are typically load-bearing (load-sparing), carrying most of the load themselves, which can lead to stress shielding of the underlying bone and potentially delayed healing. The tension band principle is specific to certain fracture types. Wolff's Law describes bone remodeling. Strain hardening is a material property. Stress shielding is aconsequenceof load-bearing implants.

Question 12524

Topic: Pelvic & Acetabular Trauma
A 7-year-old boy with Legg-Calvรฉ-Perthes disease presents with a painful limp and limited abduction. Radiographs demonstrate hinge abduction. What is the primary pathomechanical consequence of persistent hinge abduction if left untreated?
. Premature closure of the triradiate cartilage
. Prevention of femoral head remodeling by the acetabulum
. Spontaneous fusion of the hip joint
. Avascular necrosis of the acetabulum
. Overgrowth of the greater trochanter leading to coxa valga

Correct Answer & Explanation

. Prevention of femoral head remodeling by the acetabulum

Explanation

Hinge abduction occurs when the extruded, enlarged anterolateral portion of the femoral head impinges on the lateral margin of the acetabulum during abduction. Persistent hinge abduction prevents the acetabulum from effectively remodeling the femoral head, leading to a permanently deformed, aspherical femoral head (coxa magna) and early osteoarthritis. It does not cause premature closure of the triradiate cartilage or avascular necrosis of the acetabulum.

Question 12525

Topic: 2. Trauma

A 58-year-old woman who underwent a right total knee arthroplasty 2 years ago sustains a fall. Radiographs demonstrate an oblique periprosthetic distal femur fracture above a well-fixed, posterior-stabilized closed-box femoral component. Which of the following is the most appropriate surgical management?

. Retrograde intramedullary nailing
. Open reduction and internal fixation with a locked plate
. Revision to a stemmed femoral component
. Distal femoral replacement
. Closed reduction and application of a hinged knee brace

Correct Answer & Explanation

. Open reduction and internal fixation with a locked plate

Explanation

Correct Answer: Open reduction and internal fixation with a locked plateThe patient has a displaced periprosthetic distal femur fracture above a well-fixed femoral component. Because the component is a posterior-stabilized closed-box design, retrograde intramedullary nailing is contraindicated (the box prevents nail passage). Since the component is well-fixed, revision arthroplasty is unnecessary and would sacrifice bone stock. Therefore, open reduction and internal fixation (ORIF) with a locked laterally based plate is the most appropriate treatment to provide stable fixation while preserving the prosthesis.

Question 12526

Topic: 2. Trauma

A 7-year-old girl presents with a painful volar forearm mass. Radiographs demonstrate multiple small, rounded calcifications within the soft tissues. MRI reveals a heterogeneous intramuscular mass with increased signal intensity on T1-weighted images, suggesting interspersed fat. What do the calcifications seen on the radiographs most likely represent?

. Dystrophic calcification from prior trauma
. Phleboliths associated with a hemangioma
. Chondroid matrix of an extraskeletal chondroma
. Ossification within a myositis ossificans lesion
. Calcified granulomas from a prior infection

Correct Answer & Explanation

. Phleboliths associated with a hemangioma

Explanation

Correct Answer: Phleboliths associated with a hemangiomaThe presence of small, rounded calcifications in a soft-tissue mass on radiographs is highly suggestive of phleboliths, which are calcified thrombi within the venous channels of a hemangioma. The MRI findings of a heterogeneous mass with high T1 signal (due to interspersed fat) further support the diagnosis of an intramuscular hemangioma. Myositis ossificans typically shows peripheral ossification, while chondroid matrix usually appears as stippled or rings-and-arcs calcifications.

Question 12527

Topic: 2. Trauma

A patient presents with acute knee swelling following trauma. T1- and T2-weighted MRI scans are shown, demonstrating a characteristic layering effect within the joint effusion. This finding is most strongly associated with which of the following underlying injuries?

. Isolated anterior cruciate ligament tear
. Medial meniscus bucket-handle tear
. Intra-articular fracture
. Patellar tendon rupture
. Septic arthritis

Correct Answer & Explanation

. Intra-articular fracture

Explanation

Correct Answer: CThe MRI scans demonstrate a lipohemarthrosis, characterized by the layering of fat (superiorly, high signal on T1), serum (centrally), and red blood cells (inferiorly, low signal). The most common cause of a lipohemarthrosis is an intra-articular fracture, which allows marrow fat to escape into the joint space. While an ACL tear can cause a hemarthrosis, it typically does not produce a lipohemarthrosis unless accompanied by an osteochondral fracture.

Question 12528

Topic: 2. Trauma
A 25-year-old man sustains a closed, isolated Pauwels type III (vertical shear) femoral neck fracture. Biomechanically, which of the following internal fixation constructs provides the greatest stability and is most appropriate for this specific fracture pattern?
. Three parallel cancellous screws
. Fixed-angle sliding hip screw
. Two divergent cancellous screws
. Unipolar hemiarthroplasty
. Total hip arthroplasty

Correct Answer & Explanation

. Fixed-angle sliding hip screw

Explanation

Vertical shear (Pauwels III) fractures experience high shear forces that predispose to varus collapse and nonunion. A fixed-angle device, such as a sliding hip screw, provides superior biomechanical stability against these vertical shear forces compared to multiple cancellous screws.

Question 12529

Topic: 2. Trauma

A 22-year-old man presents with a scaphoid proximal pole fracture. He is counseled regarding the high risk of nonunion and avascular necrosis. The vulnerability of the proximal pole to ischemia is due to its blood supply primarily entering distally. Which of the following arteries provides this retrograde vascular supply?

. Volar carpal branch of the radial artery
. Superficial palmar arch
. Dorsal carpal branch of the radial artery
. Deep palmar arch
. Anterior interosseous artery

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

The primary blood supply to the scaphoid enters the dorsal ridge distally via the dorsal carpal branch of the radial artery. Because the flow is retrograde, proximal pole fractures have a high risk of avascular necrosis and nonunion.

Question 12530

Topic: Pelvic & Acetabular Trauma
A 35-year-old male is brought to the trauma bay following a motorcycle collision. He is hemodynamically unstable and radiographs reveal an Anteroposterior Compression (APC) type III pelvic ring injury. A pelvic binder is applied. Which of the following ligamentous structures provides the primary restraint to external rotation of the hemipelvis?
. Anterior sacroiliac ligament
. Sacrotuberous ligament
. Posterior sacroiliac ligament
. Iliolumbar ligament
. Sacrospinous ligament

Correct Answer & Explanation

. Anterior sacroiliac ligament

Explanation

The anterior sacroiliac ligament is the primary restraint to external rotation of the hemipelvis. In APC injuries, the symphysis fails first, followed by the sacrotuberous/sacrospinous ligaments, and finally the anterior sacroiliac ligament, causing profound external rotational instability.

Question 12531

Topic: 2. Trauma

A 32-year-old male undergoes locked intramedullary nailing of a closed diaphyseal tibia fracture. Radiographs at 12 weeks show robust fracture callus formation. This type of secondary bone healing is predominantly driven by which of the following biomechanical environments?

. Absolute stability with low strain
. Absolute stability with high strain
. Relative stability with moderate strain
. Relative stability with extremely high strain (>30%)
. Dynamic compression with zero strain

Correct Answer & Explanation

. Relative stability with moderate strain

Explanation

Secondary bone healing (callus formation) is promoted by a biomechanical environment providing relative stability with moderate interfragmentary strain (typically 2-10%). Intramedullary nailing perfectly provides this dynamic mechanobiological environment.

Question 12532

Topic: 2. Trauma

A 55-year-old female undergoes volar locking plate fixation for a displaced intra-articular distal radius fracture.

At her 6-week follow-up, she complains of a sudden inability to actively extend her thumb interphalangeal joint. What is the most likely etiology?

. Radial nerve neurapraxia
. Posterior interosseous nerve entrapment
. Avulsion of the extensor pollicis brevis
. Attritional rupture of the extensor pollicis longus tendon
. Unrecognized acute compartment syndrome

Correct Answer & Explanation

. Attritional rupture of the extensor pollicis longus tendon

Explanation

Attritional rupture of the extensor pollicis longus (EPL) tendon is a known complication following distal radius fractures, both conservatively and surgically managed. It can occur due to prominent dorsal screws or ischemic attrition from fracture hematoma and callus in the third extensor compartment.

Question 12533

Topic: 2. Trauma
A 35-year-old male sustains a high-speed motor vehicle collision resulting in a vertically oriented (Pauwels III) femoral neck fracture. Which of the following fixation constructs offers the most biomechanical stability against the high shear forces inherent to this fracture pattern?
. Three parallel cancellous screws
. Sliding hip screw with an anti-rotation screw
. Standard cephalomedullary nail
. Proximal femoral locking plate
. Dynamic condylar screw

Correct Answer & Explanation

. Sliding hip screw with an anti-rotation screw

Explanation

Pauwels III (vertical) femoral neck fractures experience high shear forces and varus instability. A sliding hip screw combined with an anti-rotation screw provides superior biomechanical stability against these shear stresses compared to multiple parallel cancellous screws.

Question 12534

Topic: 2. Trauma

A 32-year-old male is admitted with a closed, comminuted tibial shaft fracture. Twelve hours later, he reports severe, unrelenting leg pain out of proportion to the injury, unrelieved by opioid analgesics. Which physical examination finding is considered the most sensitive and earliest clinical indicator of acute compartment syndrome?

. Pulselessness of the dorsalis pedis artery
. Paralysis of the extensor hallucis longus
. Pallor of the foot
. Pain with passive stretch of the involved muscles
. Paresthesias in the first web space

Correct Answer & Explanation

. Pain with passive stretch of the involved muscles

Explanation

Pain with passive stretch of the ischemic muscles is widely considered the earliest and most sensitive clinical hallmark of acute compartment syndrome. Findings like pulselessness and paralysis are late, often irreversible signs indicating established necrosis.

Question 12535

Topic: 2. Trauma

A 3-day-old female infant, born via breech presentation, presents for a routine newborn examination. On physical examination, you detect a 'clunk' as the hip is abducted and gently lifted. Which of the following describes this specific finding?

. Galeazzi sign
. Barlow maneuver
. Ortolani maneuver
. Trendelenburg sign
. Limited hip abduction

Correct Answer & Explanation

. Ortolani maneuver

Explanation

The Ortolani maneuver is a specific physical examination test used to reduce a dislocated hip in an infant. It is performed by abducting the flexed hip while applying gentle upward pressure, feeling for a 'clunk' as the femoral head re-enters the acetabulum. The Barlow maneuver, in contrast, attempts to dislocate an unstable hip by adducting and posteriorly directing pressure on the flexed hip. The Galeazzi sign (or Allis sign) indicates a limb length discrepancy due to a shorter tibia or femur, often seen in older infants with unilateral hip dislocation. Trendelenburg sign is for gluteal abductor weakness, typically in ambulating children. Limited hip abduction is a sign, not a maneuver.

Question 12536

Topic: 2. Trauma

A 9-month-old female presents with a waddling gait and a suspected left hip dislocation. On physical examination, the left knee appears lower than the right when both hips and knees are flexed and feet are flat on the examination table. This finding is known as:

. Trendelenburg sign
. Barlow sign
. Galeazzi sign
. Ortolani sign
. Piston mobility

Correct Answer & Explanation

. Galeazzi sign

Explanation

The Galeazzi sign (also known as the Allis sign) is present when, with the patient supine and hips and knees flexed to 90 degrees with the feet flat on the table, one knee appears lower than the other. This indicates a limb length discrepancy, which in the context of DDH, suggests a dislocated hip on the side of the lower knee (due to proximal migration of the femur). Trendelenburg indicates abductor weakness. Barlow and Ortolani are maneuvers for hip instability in neonates/young infants. Piston mobility refers to excessive superior-inferior movement of the femoral head in the acetabulum, indicating instability.

Question 12537

Topic: 2. Trauma

A 3-week-old female infant, born in a cephalic presentation, has no family history of DDH. On routine examination, her left hip is stable. However, when the hip is flexed to 90 degrees, adducted, and a posterior force is applied, a 'clunk' is felt as the femoral head displaces posteriorly out of the acetabulum. This finding is indicative of:

. A positive Ortolani sign
. A positive Barlow sign
. A positive Galeazzi sign
. A dislocated hip
. A reducible subluxation

Correct Answer & Explanation

. A positive Barlow sign

Explanation

This maneuver describes the Barlow test. A positive Barlow sign indicates an unstable hip that is dislocatable. The Ortolani test (a 'clunk' with reduction) assesses a dislocated hip that is reducible. A dislocated hip means the femoral head is already out of the acetabulum. A reducible subluxation is a less severe form of instability, where the hip moves partially out but can be reduced. The Galeazzi sign is a limb length discrepancy. The description is classic for the Barlow maneuver.

Question 12538

Topic: Pelvic & Acetabular Trauma

When performing the Barlow maneuver, what is the primary direction of force applied to the femoral head to test for instability?

. Anterior and superior
. Posterior and lateral
. Posterior and inferior
. Anterior and medial
. Posterior and superior

Correct Answer & Explanation

. Posterior and lateral

Explanation

In the Barlow maneuver, the hip is flexed and adducted, and a posterior (downward towards the table) and slightly lateral force is applied to the knee/thigh, attempting to dislocate the femoral head posteriorly out of the acetabulum. The Ortolani maneuver involves anterior and superior force to reduce a dislocated hip.

Question 12539

Topic: Pelvic & Acetabular Trauma

Which radiographic line or angle is primarily used to assess acetabular depth and coverage of the femoral head in children over 4-6 months of age?

. Shenton's line
. Perkin's line
. Hilgenreiner's line
. Acetabular index (angle)
. Wiberg's CE angle

Correct Answer & Explanation

. Acetabular index (angle)

Explanation

The acetabular index (or acetabular angle) is formed by a line drawn from the triradiate cartilage to the lateral edge of the acetabular roof and Hilgenreiner's line (a horizontal line connecting the inferior margins of the triradiate cartilages). An increased acetabular index indicates a shallow, dysplastic acetabulum. Hilgenreiner's line and Perkin's line (perpendicular to Hilgenreiner's, drawn from the lateral edge of the acetabulum) create quadrants for assessing femoral head position. Shenton's line assesses the alignment of the medial femoral neck and superior obturator foramen. Wiberg's CE angle (center-edge angle) is used in older children and adults to assess lateral femoral head coverage, not typically in infants for initial dysplasia assessment.

Question 12540

Topic: 2. Trauma

What is the significance of a 'false acetabulum' observed on radiographs in an older child with long-standing DDH?

. It indicates a successfully reduced hip.
. It represents a primary acetabular dysplasia that has matured.
. It is an articulation formed by the femoral head against the ilium superior to the true acetabulum.
. It is a normal variant of hip development.
. It suggests a pathological fracture of the acetabulum.

Correct Answer & Explanation

. It is an articulation formed by the femoral head against the ilium superior to the true acetabulum.

Explanation

A 'false acetabulum' or 'neoacetabulum' develops in long-standing, unreduced hip dislocation in older children and adults. It is a shallow, often dysplastic, articulation that forms on the lateral aspect of the ilium superior to the true acetabulum, where the femoral head has been chronically articulating. It is a compensatory change to chronic dislocation, not a sign of successful reduction, normal development, or fracture.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page