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2. Trauma MCQs

Practice Set 420 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 8381

Topic: 2. Trauma

When utilizing a laterally based locking plate for a highly comminuted supracondylar distal femur fracture (AO/OTA type 33-C), which of the following technical modifications decreases the construct stiffness and promotes secondary bone healing through callus formation?

. Filling all screw holes in the diaphyseal portion of the plate
. Using shorter plates to localize the stress forces at the fracture site
. Decreasing the working length of the construct
. Increasing the working length of the construct
. Placing a lag screw outside the plate in a transverse fracture pattern

Correct Answer & Explanation

. Increasing the working length of the construct

Explanation

In comminuted fractures bridged by a locking plate, secondary bone healing (callus formation) relies on relative stability, which requires a small amount of controlled interfragmentary motion. 'Working length' is the distance between the two innermost screws flanking the fracture. Increasing the working length (leaving screw holes empty near the fracture site) decreases the rigidity of the construct, allowing for micro-motion and promoting robust callus formation. Filling all holes or using short plates makes the construct too stiff, leading to a high risk of nonunion or implant failure.

Question 8382

Topic: 2. Trauma
A 25-year-old intubated polytrauma patient has a closed, comminuted midshaft tibia fracture. The leg is tense and significantly swollen. Compartment pressure measurements are obtained using a handheld manometer: Anterior 45 mmHg, Lateral 40 mmHg, Deep Posterior 50 mmHg, Superficial Posterior 30 mmHg. The patient's blood pressure is 110/65 mmHg (MAP 80 mmHg). What is the most appropriate next step in management?
. Administer intravenous mannitol
. Elevate the affected limb above the level of the heart
. Observe with serial physical examinations every 4 hours
. Perform urgent four-compartment fasciotomies of the leg
. Apply a negative pressure wound therapy dressing over the closed skin

Correct Answer & Explanation

. Perform urgent four-compartment fasciotomies of the leg

Explanation

The diagnosis of acute compartment syndrome in an obtunded or intubated patient relies on objective pressure measurements. The most reliable criterion is the 'Delta P' (ΔP), which is calculated as the Diastolic Blood Pressure minus the highest intracompartmental pressure. A ΔP of less than 30 mmHg is an absolute indication for fasciotomy. In this patient, the diastolic BP is 65 mmHg, and the highest compartment pressure is 50 mmHg (Deep Posterior). The ΔP is 15 mmHg (65 - 50 = 15), which is well below the 30 mmHg threshold, indicating acute compartment syndrome. The definitive treatment is an urgent four-compartment fasciotomy.

Question 8383

Topic: 2. Trauma
A 30-year-old man sustains a Gustilo-Anderson IIIB open tibia fracture following an industrial accident. He undergoes immediate aggressive surgical debridement, irrigation, and application of a spanning external fixator. A second-look debridement confirms a clean, viable wound bed with exposed bone devoid of periosteum. To minimize the risk of deep infection, what is the optimal timeframe for performing definitive soft-tissue coverage (e.g., a free tissue transfer)?
. Within 3 to 7 days of the injury
. Between 10 and 14 days of the injury
. Between 3 and 4 weeks of the injury
. After 6 weeks, once soft tissues have completely granulated
. Only after definitive bony union is achieved

Correct Answer & Explanation

. Within 3 to 7 days of the injury

Explanation

Timing of soft-tissue coverage is critical in Gustilo IIIB open fractures. Classic studies by Godina, and more recently supported by the LEAP (Lower Extremity Assessment Project) study, demonstrate that early soft tissue coverage—optimally within 3 to 7 days (or at least less than 7 days)—significantly reduces the rates of deep infection, flap failure, and nonunion. Delaying coverage beyond this 'subacute' window allows bacterial colonization and fibrosis, dramatically increasing complication rates.

Question 8384

Topic: 2. Trauma
A 42-year-old male is brought to the trauma bay after a high-speed motorcycle collision. He has an anteroposterior compression type III (APC-III) pelvic ring injury. His initial blood pressure is 70/40 mmHg. A pelvic binder is applied appropriately at the level of the greater trochanters, and 2 units of uncrossmatched packed red blood cells are administered. The FAST (Focused Assessment with Sonography for Trauma) exam is negative, and his chest radiograph is unremarkable. Despite these measures, his blood pressure remains 75/45 mmHg. What is the most appropriate next step in management?
. Application of a supra-acetabular external fixator
. Preperitoneal pelvic packing and/or pelvic angioembolization
. Exploratory laparotomy
. Diagnostic peritoneal lavage
. Administration of tranexamic acid and continued fluid resuscitation

Correct Answer & Explanation

. Preperitoneal pelvic packing and/or pelvic angioembolization

Explanation

According to Advanced Trauma Life Support (ATLS) and current orthopedic trauma guidelines, a hemodynamically unstable patient with a pelvic ring disruption and a negative FAST exam (ruling out massive intra-abdominal hemorrhage) requires immediate pelvic hemorrhage control. After mechanical stabilization with a binder, the next step for persistent shock is preperitoneal pelvic packing or pelvic angioembolization. Exploratory laparotomy is incorrect in the setting of a negative FAST, as opening the peritoneum can release the tamponade effect on the retroperitoneal hematoma. External fixation alone is insufficient for severe hemodynamic instability once a binder is already in place.

Question 8385

Topic: 2. Trauma
A 25-year-old male sustains a vertically oriented, displaced basicervical femoral neck fracture (Pauwels III) following a fall from a height. Which of the following fixation constructs provides the greatest biomechanical stability and highest resistance to vertical shear forces for this specific fracture pattern?
. Three parallel cancellous screws in an inverted triangle configuration
. A sliding hip screw with a derotational cancellous screw
. A fully threaded positioning screw combined with two partially threaded screws
. A proximal femoral locking plate
. Dual non-sliding intramedullary hip screws

Correct Answer & Explanation

. A sliding hip screw with a derotational cancellous screw

Explanation

Pauwels III fractures are vertically oriented (angle > 50 degrees) and experience high vertical shear forces, leading to a high rate of varus collapse, nonunion, and failure when treated with multiple cancellous screws alone. Biomechanical studies have consistently demonstrated that a fixed-angle device, such as a sliding hip screw (SHS), provides superior resistance to vertical shear compared to cancellous screws. A derotational cancellous screw is typically added superior to the SHS to prevent rotation of the femoral head during insertion and weight-bearing.

Question 8386

Topic: 2. Trauma

A 45-year-old male smoker sustains a high-energy closed tibial pilon fracture (OTA/AO 43C3) with severe soft tissue swelling and fracture blisters. A spanning external fixator is placed on the day of injury. Definitive open reduction and internal fixation (ORIF) is planned. Which of the following physical examination findings is the most reliable clinical indicator that the soft tissues are ready for definitive surgical incisions?

. Return of palpable dorsalis pedis and posterior tibial pulses
. Re-epithelialization of hemorrhagic fracture blisters
. Appearance of skin wrinkles on the anterior and medial ankle
. Resolution of pitting edema to the level of the mid-calf
. Normalization of inflammatory markers (ESR and CRP)

Correct Answer & Explanation

. Appearance of skin wrinkles on the anterior and medial ankle

Explanation

In high-energy pilon fractures, the single most important factor in preventing catastrophic postoperative wound complications is respecting the soft tissue envelope. The 'wrinkle sign'—the appearance of fine skin lines/wrinkles when the ankle is dorsiflexed or naturally resting—is the most reliable clinical indicator that swelling has subsided sufficiently to allow for safe surgical incisions. This typically takes 10 to 21 days. Fracture blisters should be allowed to re-epithelialize, but the wrinkle sign is the definitive metric for overall tissue tension.

Question 8387

Topic: 2. Trauma

During a two-incision, four-compartment fasciotomy for acute compartment syndrome of the lower leg, a surgeon releases the anterior and lateral compartments through an anterolateral incision, and the superficial posterior compartment through a posteromedial incision. However, the patient later develops claw toes and contractures. Which compartment was most likely missed or inadequately released due to failure to detach the soleus bridge from the fibula?

. Anterior compartment
. Lateral compartment
. Superficial posterior compartment
. Deep posterior compartment
. Peroneal compartment

Correct Answer & Explanation

. Deep posterior compartment

Explanation

The deep posterior compartment is the most commonly missed or inadequately released compartment during a lower extremity fasciotomy. It contains the tibialis posterior, flexor hallucis longus, flexor digitorum longus, and the posterior tibial neurovascular bundle. To adequately release this compartment through the posteromedial incision, the surgeon must identify and release the fascial attachments of the soleus muscle off the posterior aspect of the tibia and ensure the deep fascia covering the tibialis posterior is fully opened.

Question 8388

Topic: 2. Trauma
A 30-year-old farmer sustains a severe open midshaft tibia fracture (Gustilo-Anderson Grade IIIA) after his leg is caught in a tractor mechanism. The wound is heavily contaminated with soil and manure. According to classic orthopedic trauma guidelines, what is the most appropriate initial prophylactic antibiotic regimen?
. Cefazolin alone
. Cefazolin and an aminoglycoside
. Cefazolin, an aminoglycoside, and high-dose penicillin
. Ciprofloxacin and clindamycin
. Vancomycin and ceftriaxone

Correct Answer & Explanation

. Cefazolin, an aminoglycoside, and high-dose penicillin

Explanation

For severe open fractures heavily contaminated with farm material, soil, or stagnant water, there is a high risk of anaerobic infection, particularly Clostridium species, in addition to standard Gram-positive and Gram-negative organisms. The classic board-tested regimen for farm injuries is a first-generation cephalosporin (Cefazolin) for Gram-positives, an aminoglycoside (e.g., Gentamicin) for Gram-negatives, and Penicillin to cover anaerobes like Clostridium perfringens. While modern practices sometimes substitute this with Ceftriaxone/Metronidazole or Piperacillin-Tazobactam, the triple-therapy option remains the classic standard correct answer for farm contamination.

Question 8389

Topic: 2. Trauma

A 28-year-old male sustains a closed spiral fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). In the emergency department, he is noted to have a complete radial nerve palsy that was present immediately upon injury. What is the most appropriate initial management?

. Immediate open reduction internal fixation and primary nerve repair
. Closed reduction, application of a coaptation splint, and clinical observation
. Application of a bridging external fixator to avoid compression
. Immediate electromyography (EMG) and nerve conduction studies
. Urgent MRI of the arm to determine if the nerve is entrapped

Correct Answer & Explanation

. Closed reduction, application of a coaptation splint, and clinical observation

Explanation

A primary radial nerve palsy in the setting of a closed humeral shaft fracture (including the Holstein-Lewis distal third spiral variant) is generally treated expectantly with closed reduction and functional bracing or splinting. The vast majority (>70-80%) of these nerve injuries are neuropraxias that will spontaneously recover within 3 to 4 months. Immediate nerve exploration is indicated for open fractures, penetrating injuries, or a secondary palsy (one that occursaftera closed reduction attempt). EMG is not useful in the acute setting as Wallerian degeneration takes 3-4 weeks to become evident.

Question 8390

Topic: 2. Trauma

A 22-year-old polytrauma patient presents with bilateral closed femoral shaft fractures, severe bilateral pulmonary contusions, and a closed head injury with a GCS of 8. His initial lactate is 4.8 mmol/L, and his base excess is -8. Based on the principles of Damage Control Orthopedics (DCO), what is the most appropriate initial management of his femur fractures?

. Immediate bilateral reamed intramedullary nailing
. Immediate bilateral spanning external fixation
. Immediate bilateral unreamed intramedullary nailing
. Application of bilateral skeletal traction for 4 weeks
. Immediate open reduction and internal fixation with plates

Correct Answer & Explanation

. Immediate bilateral spanning external fixation

Explanation

This patient is classified as borderline or 'in extremis' based on his severe chest trauma, closed head injury, high lactate, and significant base deficit. Early Total Care (ETC) with intramedullary nailing can act as a 'second hit,' leading to ARDS or exacerbating secondary brain injury due to systemic inflammatory response and embolic showers. Damage Control Orthopedics (DCO) dictates rapid, temporary stabilization of major long bone fractures with external fixation to minimize physiological burden while the patient is resuscitated in the ICU.

Question 8391

Topic: Pelvic & Acetabular Trauma
A 42-year-old male is brought to the emergency department after a high-speed motor vehicle collision. He is hemodynamically unstable with a blood pressure of 75/40 mmHg. Pelvic radiographs reveal an anteroposterior compression (APC) type III pelvic ring injury. A pelvic binder is applied, and he receives massive transfusion protocol. His FAST exam is negative. What is the most common anatomical source of massive hemorrhage in this specific clinical presentation?
. Superior gluteal artery
. Internal pudendal artery
. Presacral venous plexus
. Cancellous bone bleeding
. Obturator artery

Correct Answer & Explanation

. Presacral venous plexus

Explanation

In pelvic ring injuries, particularly those involving widening of the sacroiliac joints and disruption of the posterior ligamentous complex (like APC III and vertical shear injuries), the most common source of massive pelvic hemorrhage (up to 80-90% of cases) is the presacral and prevesical venous plexuses, followed by cancellous bone bleeding. Arterial bleeding accounts for only 10-20% of cases. The superior gluteal artery is the most commonly injured artery, but overall venous bleeding remains the predominant source of hemodynamic instability.

Question 8392

Topic: 2. Trauma
A 28-year-old male presents with a high-energy Pauwels type III (vertical) femoral neck fracture. To minimize the risk of shear-induced displacement and nonunion, which of the following internal fixation constructs provides the highest biomechanical stability for this specific fracture pattern?
. Three parallel partially threaded 7.3mm cancellous screws
. A fixed-angle sliding hip screw with a supplemental derotational cancellous screw
. A single fully threaded 7.3mm cancellous screw placed centrally
. A standard cephalomedullary nail with a single proximal interlocking screw
. Two parallel fully threaded cancellous screws

Correct Answer & Explanation

. A fixed-angle sliding hip screw with a supplemental derotational cancellous screw

Explanation

Pauwels type III femoral neck fractures have a fracture line angle greater than 50 degrees from the horizontal, subjecting the fracture to high vertical shear forces rather than compressive forces. Biomechanical studies have consistently demonstrated that a fixed-angle sliding hip screw (SHS) combined with a supplemental derotational screw provides superior stability, highest load to failure, and least shear displacement compared to three parallel cancellous screws.

Question 8393

Topic: 2. Trauma
A 35-year-old man sustains a Gustilo-Anderson Type IIIB open fracture of the distal third of the tibia following a motorcycle crash. After aggressive serial debridement and skeletal stabilization with an intramedullary nail, a soft tissue defect measuring 8x10 cm with exposed bone devoid of periosteum remains over the anterior distal tibia. Which of the following represents the most appropriate soft-tissue coverage option?
. Medial gastrocnemius rotational flap
. Soleus rotational flap
. Local fasciocutaneous rotation flap
. Free anterolateral thigh (ALT) flap
. Split-thickness skin graft

Correct Answer & Explanation

. Free anterolateral thigh (ALT) flap

Explanation

Soft tissue defects of the distal third of the lower extremity that expose bone stripped of periosteum, tendon, or hardware typically require free tissue transfer, as local muscle flap options are limited. The medial gastrocnemius flap is ideal for the proximal third, and the soleus flap is used for the middle third of the tibia. A free flap, such as the anterolateral thigh (ALT) flap or latissimus dorsi flap, is the gold standard for coverage of the distal third of the tibia.

Question 8394

Topic: 2. Trauma
A 40-year-old male is intubated and sedated in the intensive care unit following multiple trauma, including a closed comminuted midshaft tibia fracture. The orthopedic surgeon is concerned about acute compartment syndrome. Which of the following parameters is the most reliable threshold for indicating the need for a four-compartment fasciotomy of the lower leg?
. Absolute compartment pressure consistently > 20 mmHg
. Absolute compartment pressure consistently > 30 mmHg
. Mean arterial pressure (MAP) minus compartment pressure < 40 mmHg
. Diastolic blood pressure minus compartment pressure < 30 mmHg
. Systolic blood pressure minus compartment pressure < 30 mmHg

Correct Answer & Explanation

. Diastolic blood pressure minus compartment pressure < 30 mmHg

Explanation

Current literature supports the use of the 'delta pressure' (ΔP) rather than an absolute pressure measurement to diagnose acute compartment syndrome. A delta pressure (Diastolic Blood Pressure minus absolute Compartment Pressure) of less than or equal to 30 mmHg is considered the most reliable and specific threshold indicating inadequate tissue perfusion and the need for emergent fasciotomy. Relying on absolute pressures alone often leads to overtreatment, particularly in hypotensive patients.

Question 8395

Topic: 2. Trauma

A 22-year-old motorcyclist sustains a high-energy traction injury to his right shoulder. He presents with massive soft tissue swelling, profound ecchymosis over the shoulder girdle, and an entirely flail, pulseless right upper extremity. A chest radiograph demonstrates marked lateral displacement of the right scapula relative to the spinous processes. What represents the most critical determinant of eventual limb survival and meaningful function in this condition?

. The extent of subclavian artery disruption
. The severity of concomitant complete brachial plexus avulsion
. The ability to achieve stable open reduction and internal fixation of the clavicle
. The degree of scapular body comminution
. The promptness of prophylactic four-compartment fasciotomy of the forearm

Correct Answer & Explanation

. The severity of concomitant complete brachial plexus avulsion

Explanation

The clinical scenario and radiographic findings are pathognomonic for scapulothoracic dissociation. This is a severe, high-energy traction injury. While vascular injuries (typically the subclavian or axillary artery) dictate immediate limb survival and require emergent attention, the ultimate functional outcome and usefulness of the salvaged limb are almost entirely dependent on the severity of the associated brachial plexus injury. Complete avulsions of the brachial plexus carry a dismal functional prognosis, often eventually requiring amputation despite successful vascular repair.

Question 8396

Topic: 2. Trauma

A 32-year-old male is undergoing intramedullary nailing of a closed, proximal-third extra-articular tibia fracture (OTA/AO 41-A).

Which of the following typical malalignment deformities is most commonly encountered during traditional infrapatellar intramedullary nailing of this specific fracture pattern, and what is an effective strategy to prevent it?

. Apex posterior (recurvatum) and varus malalignment; prevented by placing blocking screws anterior and medial to the nail
. Apex anterior (procurvatum) and valgus malalignment; prevented by using a suprapatellar (semi-extended) nailing technique
. Apex posterior (recurvatum) and valgus malalignment; prevented by placing the limb in hyperflexion during reaming
. Apex anterior (procurvatum) and varus malalignment; prevented by placing a blocking screw medial to the nail in the proximal segment
. Pure rotational malalignment; prevented by early reaming of the distal segment prior to passing the nail

Correct Answer & Explanation

. Apex anterior (procurvatum) and valgus malalignment; prevented by using a suprapatellar (semi-extended) nailing technique

Explanation

Proximal third tibia fractures notoriously tend to displace into apex anterior (procurvatum) and valgus deformity during traditional infrapatellar intramedullary nailing. The procurvatum is caused by the pull of the patellar tendon on the proximal fragment and the posteriorly directed force of the nail insertion angle. Valgus is caused by the relatively wide proximal metaphysis failing to constrain the nail. Prevention strategies include using a suprapatellar (semi-extended) nailing technique, which neutralizes the extensor mechanism, or utilizing blocking (Poller) screws placed posteriorly and laterally in the proximal segment.

Question 8397

Topic: 2. Trauma

A 68-year-old female presents with atraumatic vague thigh pain and is found to have an incomplete atypical femoral fracture on radiographs. She has a 10-year history of alendronate therapy for osteoporosis. According to the ASBMR (American Society for Bone and Mineral Research) criteria, which of the following is considered a 'major' criterion required for the diagnosis of an atypical femoral fracture?

. Bilateral incomplete or complete femoral diaphysis fractures
. Delayed fracture healing after 12 weeks
. Localized periosteal or endosteal thickening of the lateral cortex ('beaking')
. Presence of a prodromal dull aching pain in the groin or thigh
. Concomitant long-term use of systemic glucocorticoids

Correct Answer & Explanation

. Localized periosteal or endosteal thickening of the lateral cortex ('beaking')

Explanation

According to the revised ASBMR criteria for atypical femoral fractures (AFFs), localized periosteal or endosteal thickening of the lateral cortex ('beaking' or 'flaring') is a MAJOR criterion. Other major criteria include: minimal or no trauma, a fracture line originating at the lateral cortex that is substantially transverse (though it may become oblique medially), noncomminuted or minimally comminuted, and complete fractures extending through both cortices (often with a medial spike) or incomplete fractures involving only the lateral cortex. Bilateral fractures, delayed healing, prodromal pain, and use of certain drugs (glucocorticoids, bisphosphonates) are considered MINOR criteria.

Question 8398

Topic: 2. Trauma

A 45-year-old male sustains a dashboard injury resulting in a posterior hip dislocation and a posterior wall acetabular fracture. Closed reduction of the hip is performed in the emergency department. Post-reduction CT scan demonstrates a posterior wall fracture involving 25% of the articular surface, with a 5mm area of marginal impaction. What is the most appropriate definitive management?

. Nonoperative management with skeletal traction for 6 weeks
. Open reduction and internal fixation via a Kocher-Langenbeck approach, elevating the impacted segment and bone grafting
. Open reduction and internal fixation via an Ilioinguinal approach
. Primary total hip arthroplasty
. Percutaneous iliosciatic screw fixation

Correct Answer & Explanation

. Open reduction and internal fixation via a Kocher-Langenbeck approach, elevating the impacted segment and bone grafting

Explanation

Marginal impaction refers to articular cartilage and subchondral bone that are driven into the underlying cancellous bone of the acetabulum during dislocation. Failure to recognize and elevate this segment leads to joint incongruity, instability, and early post-traumatic arthritis. The correct management is ORIF via a posterior (Kocher-Langenbeck) approach, where the impacted segment is elevated, the void is filled with bone graft, and the posterior wall is anatomically reduced and buttressed with a plate.

Question 8399

Topic: 2. Trauma

A 28-year-old female presents to the clinic 8 weeks after sustaining a Hawkins type II talar neck fracture treated with open reduction and internal fixation. She is currently non-weight-bearing. Anteroposterior radiographs of the ankle demonstrate a distinct subchondral radiolucent band extending across the dome of the talus. What is the most likely clinical significance of this radiographic finding?

. Impending hardware failure and loss of fixation
. Osteonecrosis of the talar body
. Intact vascularity to the talar body
. Septic arthritis of the tibiotalar joint
. Atrophic nonunion of the talar neck

Correct Answer & Explanation

. Intact vascularity to the talar body

Explanation

This radiographic finding describes the 'Hawkins sign', which is a subchondral radiolucent band in the talar dome that typically appears 6 to 8 weeks post-injury. The lucency is a result of subchondral bone resorption (disuse osteopenia), which can only occur if the bone has an intact vascular supply. Therefore, a positive Hawkins sign is a highly reliable indicator that avascular necrosis (AVN) of the talar body will not occur.

Question 8400

Topic: 2. Trauma
A 40-year-old male sustains a Gustilo-Anderson Type IIIB open fracture of the tibial shaft. Following serial irrigation and debridements, he is left with a clean, 10 x 8 cm soft tissue defect overlying the middle third of the tibia. There is exposed cortical bone completely devoid of periosteum. Which of the following soft tissue coverage options is most appropriate for this specific anatomical location?
. Split-thickness skin grafting over the exposed cortex
. Medial gastrocnemius rotational muscle flap
. Soleus rotational muscle flap
. Fasciocutaneous reverse sural artery flap
. Local advancement flap

Correct Answer & Explanation

. Medial gastrocnemius rotational muscle flap

Explanation

Soft tissue coverage for the leg is classically divided into thirds. Defects of the proximal third are optimally covered with a medial gastrocnemius rotational flap. The soleus rotational flap is the workhorse for middle third defects. Distal third defects typically require free tissue transfer (e.g., anterolateral thigh or latissimus dorsi flaps) due to the lack of adequate local muscle bulk, though reverse sural flaps can sometimes be used. Bare cortical bone will not support a split-thickness skin graft.

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