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2. Trauma MCQs

Practice Set 433 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 8641

Topic: 2. Trauma

A 14-year-old baseball pitcher feels a 'pop' in his medial elbow while throwing and presents with acute pain. Radiographs reveal an avulsion fracture of the medial epicondyle. Which of the following is considered an absolute indication for open reduction and internal fixation?

. Displacement greater than 5 mm
. Incarceration of the epicondylar fragment within the joint
. Valgus instability on moving valgus stress test
. High-demand throwing athlete status
. Weakness of the flexor-pronator mass

Correct Answer & Explanation

. Incarceration of the epicondylar fragment within the joint

Explanation

Absolute indications for operative fixation of a medial epicondyle fracture include an open fracture or incarceration of the fracture fragment within the elbow joint. Displacement thresholds (e.g., >5mm) and athlete demand remain relative indications and are subject to debate.

Question 8642

Topic: Pelvic & Acetabular Trauma

A 24-year-old male athlete presents with anterior groin pain exacerbated by hip flexion and internal rotation. Radiographs (

) demonstrate an abnormally elevated alpha angle. In this condition, what is the most likely location of the primary articular cartilage damage?

. Anterosuperior acetabulum
. Posteroinferior acetabulum
. Anteroinferior femoral head
. Posterosuperior femoral head
. Fovea capitis

Correct Answer & Explanation

. Anterosuperior acetabulum

Explanation

An elevated alpha angle indicates cam-type femoroacetabular impingement. The non-spherical femoral head engages the acetabulum during flexion, typically causing chondrolabral delamination and articular cartilage damage in the anterosuperior acetabulum.

Question 8643

Topic: 2. Trauma

A 78-year-old woman sustains an intertrochanteric femur fracture. Preoperative radiographs and CT (

) demonstrate a lateral wall thickness of 18 mm. What is the most appropriate surgical implant for this patient to minimize the risk of mechanical failure?

. Sliding hip screw
. Cephalomedullary nail
. Dynamic condylar screw
. Cannulated cancellous screws
. Proximal femoral locking plate

Correct Answer & Explanation

. Cephalomedullary nail

Explanation

A lateral wall thickness of less than 20.5 mm is a major predictor of secondary lateral wall fracture during dynamic hip screw insertion. Therefore, an intramedullary device (cephalomedullary nail) is preferred to bypass the deficient lateral wall.

Question 8644

Topic: 2. Trauma

A 28-year-old man sustains a posterior hip dislocation (

) in a motor vehicle collision. After closed reduction, he has a foot drop. Which specific mechanism of injury during the dislocation typically leads to this neurologic deficit?

. Stretching of the common peroneal division of the sciatic nerve
. Direct compression of the tibial division by the femoral head
. Avulsion of the lumbosacral plexus
. Compartment syndrome of the thigh
. Laceration by a bony fragment from the anterior column

Correct Answer & Explanation

. Stretching of the common peroneal division of the sciatic nerve

Explanation

The common peroneal division of the sciatic nerve is located laterally and is more superficially tethered at the fibular head. This specific anatomical arrangement makes it uniquely susceptible to stretch injury over the posteriorly dislocated femoral head.

Question 8645

Topic: 2. Trauma

A 30-year-old man sustains a displaced, basicervical femoral neck fracture.

Understanding the vascular anatomy is critical to anticipating the risk of osteonecrosis. Which vessel provides the primary blood supply to the weight-bearing dome of the adult femoral head?

. Artery of the ligamentum teres
. Inferior gluteal artery
. Medial femoral circumflex artery (MFCA)
. Lateral femoral circumflex artery (LFCA)
. Superior gluteal artery

Correct Answer & Explanation

. Medial femoral circumflex artery (MFCA)

Explanation

The medial femoral circumflex artery (MFCA) is the predominant blood supply to the adult femoral head, giving rise to the lateral epiphyseal artery system. The lateral femoral circumflex artery supplies the anterior/inferior neck, while the ligamentum teres contribution is minimal in adults.

Question 8646

Topic: 2. Trauma

A 70-year-old woman on oral alendronate for 12 years presents with an atraumatic, aching thigh pain.

Radiographs demonstrate a cortical stress reaction. Which radiographic feature is characteristic of a bisphosphonate-related atypical femur fracture?

. Spiral fracture pattern involving the mid-diaphysis with medial comminution
. Transverse or short oblique fracture pattern with focal lateral cortical thickening (beaking)
. Highly comminuted subtrochanteric fracture with profound generalized osteopenia
. Pathologic fracture occurring strictly through a lytic osseous defect
. Oblique fracture extending vertically into the greater trochanter

Correct Answer & Explanation

. Transverse or short oblique fracture pattern with focal lateral cortical thickening (beaking)

Explanation

Atypical femur fractures associated with long-term bisphosphonate use characteristically occur in the subtrochanteric or diaphyseal region. They present as transverse or short oblique fractures, non-comminuted, with localized periosteal or endosteal thickening of the lateral cortex (the "lateral beak").

Question 8647

Topic: 2. Trauma

A 78-year-old woman with a stable intertrochanteric fracture is treated with a short cephalomedullary nail. The surgeon meticulously positions the lag screw to achieve an optimal tip-apex distance (TAD). According to the classic study by Baumgaertner et al., staying below what TAD threshold minimizes the risk of lag screw cut-out?

. 10 mm
. 15 mm
. 25 mm
. 35 mm
. 45 mm

Correct Answer & Explanation

. 25 mm

Explanation

Baumgaertner et al. demonstrated that a Tip-Apex Distance (TAD) of less than 25 mm on combined AP and lateral radiographs significantly reduces the incidence of lag screw cut-out in the treatment of intertrochanteric hip fractures.

Question 8648

Topic: 2. Trauma

An 82-year-old woman sustains an unstable intertrochanteric femur fracture and is treated with a short cephalomedullary nail. Postoperative radiographs show the lag screw is positioned in the anterior-superior quadrant of the femoral head on the AP and lateral views. The combined tip-apex distance (TAD) is measured at 32 mm.

Based on these specific radiographic parameters, what is the most likely mechanical complication?

. Aseptic nonunion of the intertrochanteric fracture
. Cut-out of the lag screw through the femoral head
. Z-effect phenomenon with lateral migration of the screw
. Subtrochanteric femur fracture at the nail tip
. Rapid-onset avascular necrosis of the femoral head

Correct Answer & Explanation

. Cut-out of the lag screw through the femoral head

Explanation

The tip-apex distance (TAD), described by Baumgaertner, is the sum of the distance from the tip of the lag screw to the apex of the femoral head on both the AP and lateral radiographs. A TAD > 25 mm is the single strongest radiographic predictor of lag screw cut-out. Furthermore, placing the screw in the anterior-superior quadrant places it in mechanically inferior trabecular bone, vastly increasing the risk of the screw cutting out of the superior aspect of the femoral head during weight-bearing.

Question 8649

Topic: 2. Trauma

A 32-year-old woman presents with severe groin pain 14 months after undergoing urgent open reduction and internal fixation for a displaced femoral neck fracture. Figure 8

reveals advanced collapse of the femoral head consistent with osteonecrosis. Disruption of which of the following structures is the principal cause of this complication?

. Ligamentum teres artery
. Medial femoral circumflex artery
. Lateral femoral circumflex artery
. Inferior gluteal artery
. Superior gluteal artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The medial femoral circumflex artery (MFCA) is the predominant blood supply to the adult femoral head, specifically via its lateral epiphyseal branches. Displacement of a femoral neck fracture severely compromises these intracapsular vessels, leading to high rates of avascular necrosis (AVN), even following successful internal fixation.

Question 8650

Topic: 2. Trauma

During a primary total hip arthroplasty using a direct anterior approach (Hueter interval), the surgeon places a retractor anterior to the acetabulum to aid in exposure for reaming. In the recovery room, the patient demonstrates a profound inability to extend the knee and reports numbness over the anterior thigh. Which of the following technical errors most likely caused this complication?

. Placement of the anterior retractor over the anterior rim deep to the iliopsoas muscle
. Aggressive reaming of the anterior column of the acetabulum
. Retractor injury to the lateral femoral cutaneous nerve in the superficial interval
. Excessive traction on the operative extremity on the fracture table
. Placement of a retractor inferior to the transverse acetabular ligament

Correct Answer & Explanation

. Placement of the anterior retractor over the anterior rim deep to the iliopsoas muscle

Explanation

The patient has a femoral nerve palsy (inability to extend the knee, anterior thigh numbness). In the direct anterior approach, the femoral nerve is at risk if an anterior acetabular retractor is placed directly against the anterior acetabular rim, deep to the iliopsoas muscle. The iliopsoas normally protects the nerve, so retractors should be carefully placed over the anterior capsule but superficial to the anterior rim, or carefully avoiding capturing the nerve bundle. Lateral femoral cutaneous nerve (LFCN) injury causes purely sensory deficits (meralgia paresthetica).

Question 8651

Topic: 2. Trauma
A 32-year-old male sustains a high-energy closed fracture of the proximal femur. Radiographs reveal a completely displaced femoral neck fracture with a fracture line oriented 75 degrees from the horizontal plane (Pauwels Type III). What internal fixation construct provides the most biomechanically sound stabilization against the predominant deforming forces in this specific fracture pattern?
. Three parallel 7.3 mm cannulated screws placed in an inverted triangle configuration
. A sliding hip screw (fixed-angle device) supplemented with an anti-rotation screw
. Two fully threaded large fragment cortical screws
. A proximal femoral locking plate
. A long cephalomedullary nail

Correct Answer & Explanation

. A sliding hip screw (fixed-angle device) supplemented with an anti-rotation screw

Explanation

Pauwels Type III fractures are vertically oriented, resulting in extreme shear forces across the fracture site and a high risk of varus collapse, nonunion, and avascular necrosis. Biomechanical studies consistently show that a fixed-angle device, such as a sliding hip screw (dynamic hip screw), provides superior resistance to vertical shear forces compared to three parallel cancellous screws. An additional derotational screw is often added above the sliding hip screw to prevent femoral head rotation during insertion and weight-bearing.

Question 8652

Topic: 2. Trauma
Figure 1 shows the radiograph of a 30-year-old man who sustained a displaced, highly vertical femoral neck fracture (Pauwels type III) after a motor vehicle accident. He is planned for open reduction and internal fixation. To biomechanically optimize fixation and resist the predominant shear forces, which of the following construct configurations is most appropriate?
. Three parallel cancellous screws placed in an inverted triangle
. A sliding hip screw (SHS) with a supplemental anti-rotation screw
. Two parallel cancellous screws
. An intramedullary nail with a single cephalomedullary screw
. A dynamic condylar screw

Correct Answer & Explanation

. A sliding hip screw (SHS) with a supplemental anti-rotation screw

Explanation

Pauwels type III fractures are highly vertical and subjected to significant shear forces rather than compressive forces. In young adults where native hip preservation is paramount, a fixed-angle device such as a sliding hip screw (often supplemented with a derotational cancellous screw) provides superior biomechanical resistance to vertical shear compared to multiple parallel cancellous screws.

Question 8653

Topic: 2. Trauma
A 35-year-old man sustains a completely displaced, vertically oriented femoral neck fracture after a high-speed motor vehicle accident. The fracture angle is 65 degrees relative to the horizontal (Pauwels Type III). Regarding surgical fixation in this young adult, which of the following constructs provides the most biomechanically stable fixation to resist vertical shear forces?
. Three parallel cannulated screws placed in an inverted triangle configuration
. A sliding hip screw (dynamic hip screw) with an anti-rotation screw
. Two crossed cannulated screws
. Isolated fully threaded cancellous screws
. Proximal femoral replacement

Correct Answer & Explanation

. A sliding hip screw (dynamic hip screw) with an anti-rotation screw

Explanation

Pauwels Type III fractures (>50 degrees to the horizontal) exhibit extremely high vertical shear forces, leading to a high rate of varus collapse and nonunion when treated with traditional parallel cannulated screws. Biomechanical studies and clinical evidence show that a fixed-angle device, such as a sliding hip screw (with a derotational screw) or a modern Femoral Neck System (FNS), provides superior stability against vertical shear forces compared to multiple cannulated screws.

Question 8654

Topic: 2. Trauma
A radiograph shows a healthy 55-year-old male who sustained a vertical, displaced femoral neck fracture (Pauwels Type III) after a fall. To best resist the high vertical shear forces associated with this fracture pattern, which construct is biomechanically superior for joint-preserving fixation?
. Three parallel cannulated cancellous screws placed in an inverted triangle
. A sliding hip screw (SHS) construct with an additional anti-rotation screw
. Two parallel cannulated screws placed centrally
. A fully threaded solid screw with a spiked washer
. A dynamic condylar screw (DCS)

Correct Answer & Explanation

. A sliding hip screw (SHS) construct with an additional anti-rotation screw

Explanation

Pauwels Type III femoral neck fractures possess a highly vertical fracture line (>50 degrees), which subjects the fracture site to intense vertical shear forces that promote varus collapse and nonunion. Biomechanical studies consistently demonstrate that a sliding hip screw (SHS), particularly when supplemented with an anti-rotation cancellous screw, provides superior resistance to vertical shear forces and yields a more stable construct compared to multiple parallel cancellous screws.

Question 8655

Topic: 2. Trauma

A 32-year-old man sustains a completely displaced, high-energy intracapsular femoral neck fracture. In an adult, the viability of the femoral head following this injury is primarily dependent on which of the following arterial vessels?

. Artery of the ligamentum teres
. Ascending branch of the lateral circumflex femoral artery
. Deep branch of the medial circumflex femoral artery
. Inferior gluteal artery
. First perforating branch of the profunda femoris artery

Correct Answer & Explanation

. Deep branch of the medial circumflex femoral artery

Explanation

The deep branch of the medial circumflex femoral artery (MFCA) provides the primary blood supply to the adult femoral head via the lateral epiphyseal arteries. A displaced intracapsular femoral neck fracture heavily compromises these vessels, putting the patient at high risk for avascular necrosis (AVN). The artery of the ligamentum teres supplies a negligible amount of the head in adults.

Question 8656

Topic: 2. Trauma
A 32-year-old healthy male sustains a high-energy Pauwels type III (vertical) femoral neck fracture. Which of the following fixation constructs provides the most biomechanically sound stabilization against the significant shear forces inherent to this specific fracture pattern?
. Three parallel partially threaded cancellous screws
. Sliding hip screw with an anti-rotation screw
. Long cephalomedullary nail
. Dynamic condylar screw
. Cemented hemiarthroplasty

Correct Answer & Explanation

. Sliding hip screw with an anti-rotation screw

Explanation

Pauwels type III femoral neck fractures are highly vertical (>50 degrees) and subjected to immense shear forces, which predispose them to varus collapse, nonunion, and avascular necrosis. Biomechanical and clinical studies demonstrate that a fixed-angle construct, such as a sliding hip screw augmented with an anti-rotation cancellous screw, provides superior biomechanical stability and higher failure loads against shear stress compared to three parallel cancellous screws.

Question 8657

Topic: Pelvic & Acetabular Trauma

A 28-year-old woman with symptomatic developmental dysplasia of the hip (DDH) is undergoing a Bernese periacetabular osteotomy (PAO). Which of the following best describes the key biomechanical advantage and anatomical characteristic of this specific osteotomy technique?

. Complete detachment of the posterior column allowing maximal anterior coverage
. Preservation of an intact posterior column which maintains pelvic ring stability
. Utilization of a single iliac osteotomy hinged strictly at the pubic symphysis
. Requirement for rigid multi-segment posterior fixation extending to the sacrum
. Mandatory disruption of the obturator foramen to allow multiplanar rotation

Correct Answer & Explanation

. Preservation of an intact posterior column which maintains pelvic ring stability

Explanation

The Bernese periacetabular osteotomy (PAO), developed by Ganz, is unique in that it relies on incomplete osteotomies that preserve the continuity of the posterior column of the hemipelvis. By leaving the posterior column intact, the inherent stability of the pelvic ring is maintained. This major biomechanical advantage allows for extensive multiplanar correction of the acetabulum while minimizing blood loss and permitting early postoperative mobilization without the need for casting.

Question 8658

Topic: 2. Trauma
A 30-year-old man sustains a displaced, vertical femoral neck fracture (Pauwels Type III) following a high-energy motor vehicle collision. Open reduction and internal fixation is planned. Which of the following fixation constructs provides the greatest biomechanical stability against vertical shear forces for this specific fracture pattern?
. Three parallel partially threaded cancellous screws in an inverted triangle configuration
. Fixed-angle sliding hip screw (SHS) with an anti-rotation screw
. Two parallel fully threaded cortical screws
. Reamed intramedullary nail with a single cephalomedullary screw
. Non-locking proximal femoral plate

Correct Answer & Explanation

. Fixed-angle sliding hip screw (SHS) with an anti-rotation screw

Explanation

Pauwels Type III femoral neck fractures are characterized by a vertical fracture line (angle > 50 degrees from horizontal), which subjects the fracture to high shear forces and high rates of varus collapse and nonunion. Biomechanical studies consistently demonstrate that fixed-angle devices, such as a sliding hip screw (SHS), provide superior stability, stiffness, and load to failure compared to multiple cancellous screws for vertically oriented femoral neck fractures. An anti-rotation screw is often added superiorly to prevent rotation of the femoral head during SHS lag screw insertion and to provide additional stability.

Question 8659

Topic: 2. Trauma

A 78-year-old woman sustains a fall and presents with a periprosthetic femur fracture around a cemented polished taper-slip stem placed 8 years ago. Radiographs demonstrate a fracture just distal to the tip of the stem. The stem is well-fixed with no cement mantle fractures. According to the Vancouver classification, what is the most appropriate management?

. Revision to a long uncemented fully porous-coated stem
. Revision to a long cemented stem
. Open reduction and internal fixation with a lateral locking plate and cables
. Nonoperative management with a hinged fracture brace
. Distal femoral replacement

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locking plate and cables

Explanation

This is a Vancouver Type C periprosthetic fracture, defined as a fracture occurring well below the tip of a well-fixed stem. The treatment of choice is open reduction and internal fixation (ORIF) with a plate and screws/cables, leaving the well-fixed stem intact.

Question 8660

Topic: 2. Trauma

A 42-year-old female sustains a completely displaced femoral neck fracture (Garden IV). What is the primary source of vascular supply to the adult femoral head that is critically disrupted in this injury?

. Artery of the ligamentum teres
. Ascending branch of the lateral femoral circumflex artery
. Medial femoral circumflex artery
. Inferior gluteal artery
. Profunda femoris artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The lateral epiphyseal branches of the medial femoral circumflex artery (MFCA) provide the predominant blood supply to the adult femoral head. Displacement of a femoral neck fracture severely jeopardizes this supply.

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