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2. Trauma MCQs

Practice Set 361 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 7201

Topic: 2. Trauma

In a substantially displaced subtrochanteric femur fracture, the proximal fragment typically assumes a characteristic position of flexion, abduction, and external rotation. Which muscle is primarily responsible for the abduction deformity?

. Iliopsoas
. Gluteus maximus
. Gluteus medius
. Short external rotators
. Adductor longus

Correct Answer & Explanation

. Iliopsoas

Explanation

The typical deformity of the proximal fragment in a subtrochanteric fracture is driven by muscle attachments. The gluteus medius and minimus pull the fragment into abduction, the iliopsoas causes flexion, and the short external rotators cause external rotation.

Question 7202

Topic: 2. Trauma

Radiographs of an 82-year-old man who fell from standing reveal an intertrochanteric femur fracture with a fracture line extending from the medial cortex proximal to the lesser trochanter diagonally to the lateral cortex distal to the greater trochanter. What is the most appropriate implant for this fracture pattern?

. Multiple cannulated screws
. Dynamic hip screw (DHS)
. Cephalomedullary nail
. Proximal femoral locking plate
. Hemiarthroplasty

Correct Answer & Explanation

. Multiple cannulated screws

Explanation

This describes a reverse obliquity intertrochanteric fracture, which renders the lateral femoral wall incompetent. A dynamic hip screw is contraindicated as it permits excessive medialization of the shaft; a cephalomedullary nail is the implant of choice.

Question 7203

Topic: 2. Trauma

A 35-year-old man underwent closed reduction and percutaneous pinning of a femoral neck fracture 9 months ago. He now presents with persistent groin pain. Imaging reveals a nonunion with varus collapse, but MRI confirms the femoral head remains entirely viable. What is the most appropriate joint-preserving surgical intervention?

. Removal of hardware and core decompression
. Valgus-producing proximal femoral osteotomy
. Varus-producing proximal femoral osteotomy
. Total hip arthroplasty
. Revision fixation with a dynamic hip screw

Correct Answer & Explanation

. Removal of hardware and core decompression

Explanation

In a young patient with a femoral neck nonunion and a viable femoral head, a valgus-producing intertrochanteric osteotomy is indicated. This procedure alters the biomechanical environment, converting shear forces at the nonunion site into compressive forces, thereby promoting bone healing.

Question 7204

Topic: 2. Trauma

Which of the following fracture patterns inherently lacks cancellous bone interdigitation across the fracture site, making multiple cannulated screws an inferior biomechanical choice compared to a sliding hip screw?

. Subcapital femoral neck fracture
. Transcervical femoral neck fracture
. Basicervical femoral neck fracture
. Stable intertrochanteric femur fracture
. Greater trochanter avulsion fracture

Correct Answer & Explanation

. Subcapital femoral neck fracture

Explanation

Basicervical femoral neck fractures occur at the junction of the femoral neck and intertrochanteric line, a region that lacks cancellous bone interdigitation. Due to high instability and shear forces, a dynamic hip screw with a derotational screw or a cephalomedullary nail is mechanically superior to multiple cannulated screws.

Question 7205

Topic: 2. Trauma

When utilizing a trochanteric entry portal for a cephalomedullary nail to treat a standard intertrochanteric femur fracture, starting the guidewire too laterally on the greater trochanter is most likely to result in which of the following intraoperative complications?

. Varus malalignment of the proximal fragment
. Valgus malalignment of the proximal fragment
. Anterior perforation of the distal femur
. Fracture of the lesser trochanter
. Iatrogenic sciatic nerve injury

Correct Answer & Explanation

. Varus malalignment of the proximal fragment

Explanation

A lateral starting point for a trochanteric entry nail creates an eccentric trajectory that medializes the distal fragment and forces the proximal fragment into varus. The ideal starting point is slightly medial to the tip of the greater trochanter.

Question 7206

Topic: 2. Trauma

In the surgical treatment of intertrochanteric femur fractures using a dynamic hip screw, achieving a Tip-Apex Distance (TAD) of less than 25 mm is critical. What is the primary purpose of adhering to this measurement?

. To prevent postoperative deep vein thrombosis
. To minimize the risk of lag screw cutout from the femoral head
. To decrease the incidence of atypical femur fractures
. To ensure maximum slide of the lag screw barrel
. To avoid penetration into the acetabulum during hardware insertion

Correct Answer & Explanation

. To prevent postoperative deep vein thrombosis

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 AP and lateral radiographs. A TAD of less than 25 mm is the strongest predictor of successful fixation and minimizes the risk of screw cutout.

Question 7207

Topic: 2. Trauma

A 13-year-old boy sustains a displaced subtrochanteric femur fracture. Intramedullary nailing using a piriformis fossa entry point is considered. What is the most significant risk associated with this specific entry portal in the adolescent population?

. Nonunion of the subtrochanteric fracture
. Coxa vara deformity
. Avascular necrosis of the femoral head
. Premature closure of the greater trochanteric apophysis
. Infection

Correct Answer & Explanation

. Nonunion of the subtrochanteric fracture

Explanation

In children and adolescents, utilizing a piriformis fossa entry point for rigid intramedullary nailing severely risks disruption of the terminal branches of the medial femoral circumflex artery. This significantly increases the risk of iatrogenic avascular necrosis of the femoral head, making a lateral trochanteric entry preferred.

Question 7208

Topic: 2. Trauma

An 80-year-old woman is diagnosed with a Garden I femoral neck fracture. Which of the following best describes the radiographic appearance and optimal management of this injury?

. Complete, nondisplaced fracture; treated with hemiarthroplasty
. Incomplete or valgus-impacted fracture; treated with percutaneous in situ screw fixation
. Complete, partially displaced fracture; treated with total hip arthroplasty
. Complete, fully displaced fracture; treated with non-weight bearing for 8 weeks
. Incomplete or valgus-impacted fracture; treated with immediate full weight-bearing without surgery

Correct Answer & Explanation

. Complete, nondisplaced fracture; treated with hemiarthroplasty

Explanation

A Garden I fracture is anatomically an incomplete or valgus-impacted fracture. Although seemingly stable, there is a significant risk of secondary displacement; therefore, standard management is operative stabilization with percutaneous in situ cannulated screws.

Question 7209

Topic: 2. Trauma

The predominant blood supply to the adult femoral head, which is highly vulnerable during a displaced intracapsular femoral neck fracture, is derived primarily from which of the following vessels?

. Artery of the ligamentum teres
. Inferior gluteal artery
. Lateral circumflex femoral artery
. Lateral epiphyseal branches of the medial femoral circumflex artery
. Medial epiphyseal branches of the obturator artery

Correct Answer & Explanation

. Artery of the ligamentum teres

Explanation

The primary blood supply to the adult femoral head comes from the lateral epiphyseal arteries, which are terminal branches of the medial femoral circumflex artery (MFCA). These retinacular vessels traverse the femoral neck and are easily disrupted by displaced intracapsular fractures.

Question 7210

Topic: 2. Trauma

A surgeon is evaluating a patient with an intertrochanteric fracture to determine the risk of postoperative lateral wall fracture if a dynamic hip screw (DHS) is used. According to the literature, an intact lateral wall thickness below what threshold on the preoperative anteroposterior radiograph strongly contraindicates the use of a DHS?

. 10.5 mm
. 15.5 mm
. 20.5 mm
. 25.5 mm
. 30.5 mm

Correct Answer & Explanation

. 10.5 mm

Explanation

A lateral wall thickness of less than 20.5 mm in intertrochanteric fractures has been shown to be a critical predictor for postoperative lateral wall blowout when treated with a DHS. In such cases, a cephalomedullary nail should be utilized instead.

Question 7211

Topic: 2. Trauma

Which of the following parameters is an absolute indication for open reduction of a posterior hip dislocation rather than proceeding with an initial closed reduction attempt in the emergency department?

. Associated nondisplaced posterior wall acetabular fracture
. Ipsilateral displaced femoral neck fracture
. Presence of a sciatic nerve palsy prior to reduction
. Delay in presentation of more than 6 hours
. Patient age greater than 65 years

Correct Answer & Explanation

. Associated nondisplaced posterior wall acetabular fracture

Explanation

An ipsilateral displaced femoral neck fracture is an absolute contraindication to closed reduction of a hip dislocation. Attempting closed reduction will distract the neck fracture without moving the head, causing further soft tissue and vascular damage, and necessitates open surgical management.

Question 7212

Topic: 2. Trauma

A 72-year-old man falls and sustains a reverse obliquity intertrochanteric fracture of the left femur. Which of the following fixation constructs offers the highest biomechanical stability and lowest risk of failure for this specific fracture pattern?

. Multiple parallel cannulated screws
. Sliding hip screw with a 4-hole side plate
. Cephalomedullary nail
. Dynamic condylar screw
. Proximal femoral locking plate

Correct Answer & Explanation

. Multiple parallel cannulated screws

Explanation

Reverse obliquity intertrochanteric fractures are highly unstable due to the tendency of the femoral shaft to medialize from adductor forces. Intramedullary devices (cephalomedullary nails) provide superior biomechanical stability and significantly lower failure rates compared to extramedullary devices like sliding hip screws.

Question 7213

Topic: 2. Trauma

During closed reduction of a subtrochanteric femur fracture in a 35-year-old man, the proximal fragment remains persistently flexed, abducted, and externally rotated. Which muscle is primarily responsible for the flexion and external rotation of the proximal segment?

. Gluteus medius
. Adductor longus
. Iliopsoas
. Tensor fasciae latae
. Vastus lateralis

Correct Answer & Explanation

. Gluteus medius

Explanation

In subtrochanteric fractures, the proximal fragment is flexed and externally rotated primarily by the iliopsoas muscle. The gluteus medius and minimus are responsible for the abduction deformity.

Question 7214

Topic: 2. Trauma

When treating an intertrochanteric femur fracture with a sliding hip screw or cephalomedullary nail, the tip-apex distance (TAD) is a critical predictor of lag screw cut-out. According to Baumgaertner, what is the recommended maximum TAD to minimize this complication?

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

Correct Answer & Explanation

. 10 mm

Explanation

Baumgaertner demonstrated that a tip-apex distance (TAD) of less than 25 mm significantly reduces the risk of lag screw cut-out. The TAD is the sum of the distances from the screw tip to the apex of the femoral head on both AP and lateral radiographs.

Question 7215

Topic: 2. Trauma
A 40-year-old man sustains a posterior hip dislocation with an associated fracture of the femoral head and a posterior wall acetabular fracture. According to the Pipkin classification, what type of fracture-dislocation is this?
. Pipkin Type I
. Pipkin Type II
. Pipkin Type III
. Pipkin Type IV
. Pipkin Type V

Correct Answer & Explanation

. Pipkin Type IV

Explanation

The Pipkin classification describes femoral head fractures associated with posterior hip dislocations. Type IV is defined as a femoral head fracture associated with an acetabular fracture (typically a posterior wall fracture).

Question 7216

Topic: 2. Trauma

A 78-year-old woman presents with severe hip pain and an inability to bear weight after a mechanical fall from standing height. Anteroposterior and cross-table lateral radiographs of the hip are entirely negative for fracture. What is the most appropriate next step in diagnosis?

. CT scan of the pelvis without contrast
. Bone scintigraphy
. Diagnostic ultrasound of the hip joint
. Magnetic resonance imaging (MRI) of the hip
. Repeat plain radiographs in 10-14 days while weight-bearing as tolerated

Correct Answer & Explanation

. CT scan of the pelvis without contrast

Explanation

In patients with a strong clinical suspicion of an occult proximal femur fracture but negative plain radiographs, MRI is the gold standard diagnostic test. It is highly sensitive and specific, allowing for immediate diagnosis and prevention of fracture displacement.

Question 7217

Topic: 2. Trauma
A 32-year-old man sustains a vertically oriented, displaced femoral neck fracture (Pauwels Type III) after a fall from a height. Which of the following internal fixation constructs is biomechanically superior for resisting the high shear forces associated with this fracture pattern?
. Three parallel cannulated screws in an inverted triangle
. Two parallel cannulated screws
. A sliding hip screw with a derotation screw
. A dynamic condylar screw without derotation screw
. A single large-diameter fully threaded screw

Correct Answer & Explanation

. A sliding hip screw with a derotation screw

Explanation

Pauwels Type III fractures (>50 degrees) experience high vertical shear forces, leading to high rates of displacement and nonunion with standard cannulated screws. A length-stable construct, such as a sliding hip screw augmented with a derotation screw, provides superior biomechanical stability against these forces.

Question 7218

Topic: 2. Trauma

A 45-year-old man presents with groin pain 8 months after internal fixation of a displaced femoral neck fracture with three cannulated screws. Radiographs reveal a nonunion with screw back-out, but MRI confirms the femoral head is fully viable with no osteonecrosis. What is the most appropriate surgical treatment?

. Total hip arthroplasty
. Bipolar hemiarthroplasty
. Removal of hardware and valgus intertrochanteric osteotomy
. Removal of hardware and core decompression
. Revision internal fixation with a sliding hip screw

Correct Answer & Explanation

. Total hip arthroplasty

Explanation

In a young, active patient with a viable femoral head and a femoral neck nonunion, a valgus intertrochanteric osteotomy is the treatment of choice. This alters the biomechanics by converting vertical shear forces at the nonunion site into compressive forces, which promotes healing.

Question 7219

Topic: 2. Trauma

A 65-year-old woman on long-term alendronate therapy complains of a dull ache in her right thigh. Radiographs reveal focal lateral cortical thickening and a transverse radiolucent line in the subtrochanteric region. What is the pathognomonic radiographic feature of a complete fracture of this type if it were to displace?

. A long oblique fracture line with extensive medial comminution
. A medial spike on the proximal fragment
. A medial spike on the distal fragment
. Severe osteopenia of the surrounding cortical bone
. A spiral fracture extending proximally into the greater trochanter

Correct Answer & Explanation

. A long oblique fracture line with extensive medial comminution

Explanation

Atypical femoral fractures (AFFs) associated with bisphosphonate use originate at the lateral cortex and have a transverse orientation. If they complete and displace, they classically demonstrate a characteristic medial spike on the proximal fragment with minimal to no comminution.

Question 7220

Topic: 2. Trauma

A 75-year-old woman sustains a ground-level fall. Radiographs demonstrate a reverse obliquity intertrochanteric fracture of the proximal femur. Which of the following implants is biomechanically most appropriate for this fracture pattern?

. Three parallel cannulated cancellous screws
. Sliding hip screw (dynamic hip screw)
. Cephalomedullary nail
. Standard locked proximal femoral plate
. Dynamic condylar screw

Correct Answer & Explanation

. Three parallel cannulated cancellous screws

Explanation

Reverse obliquity fractures are highly unstable and have a high failure rate when treated with a sliding hip screw due to lateral displacement of the distal fragment. A cephalomedullary nail or a fixed-angle device like a 95-degree blade plate is the preferred treatment to adequately neutralize the deforming forces.

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