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2. Trauma MCQs

Practice Set 634 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 12661

Topic: Lower Extremity Trauma

A full-length standing AP radiograph of the lower extremities is obtained to evaluate a patient's deformity. The mechanical lateral distal femoral angle (mLDFA) is measured at 99 degrees, and the medial proximal tibial angle (MPTA) is measured at 87 degrees. What is the correct interpretation of these radiographic findings?

. Normal alignment of both the femur and the tibia.
. Varus deformity of the distal femur with a normal proximal tibia.
. Valgus deformity of the distal femur with a normal proximal tibia.
. Normal distal femur with a varus deformity of the proximal tibia.
. Valgus deformity of both the distal femur and proximal tibia.

Correct Answer & Explanation

. Varus deformity of the distal femur with a normal proximal tibia.

Explanation

The normal mLDFA is approximately 87-88 degrees (range 85-90). An mLDFA of 99 degrees indicates an abnormally large lateral angle, meaning the distal femur is in varus. The normal MPTA is also approximately 87 degrees, so the tibia is normal.

Question 12662

Topic: Lower Extremity Trauma

A 16-year-old male with a 6-cm post-traumatic femoral length discrepancy is undergoing lengthening over a nail (LON). Compared to classic Ilizarov lengthening using only an external fixator, what is the primary advantage of the LON technique?

. Decreased risk of deep intramedullary infection.
. Elimination of the need for an osteotomy.
. Significantly reduced time required in the external fixator.
. Ability to correct larger rotational deformities simultaneously.
. Prevention of pin-track infections during the distraction phase.

Correct Answer & Explanation

. Significantly reduced time required in the external fixator.

Explanation

Lengthening over a nail (LON) allows the external fixator to be removed immediately after the distraction phase is completed, with the intramedullary nail locked to support the bone during the prolonged consolidation phase. This dramatically reduces the time the patient must wear the external frame.

Question 12663

Topic: 2. Trauma

A 10-year-old girl with a history of a physeal fracture develops a 4 cm leg length discrepancy and is treated with a circular external fixator for tibial lengthening. Four weeks into the distraction phase, she complains of increasing pain, redness, and a small amount of purulent drainage at a single proximal wire site. She is afebrile. Based on the Checketts-burns classification, what is the best initial management?

. Immediate admission for intravenous vancomycin and wire removal.
. Oral antibiotics, enhanced local pin site care, and continued distraction.
. Stopping distraction entirely and initiating suppressive oral antibiotics.
. Surgical debridement of the pin tract and conversion to an intramedullary nail.
. Observation alone, as seropurulent drainage is normal during active distraction.

Correct Answer & Explanation

. Oral antibiotics, enhanced local pin site care, and continued distraction.

Explanation

Superficial pin site infections are extremely common during external fixation. The initial management for a localized, superficial infection (erythema, localized drainage, no systemic signs) is aggressive local pin site care and a course of oral antibiotics. Removal of the wire is reserved for refractory cases or deep infections.

Question 12664

Topic: Lower Extremity Trauma

A 28-year-old male is undergoing assessment for varus malalignment of the lower extremity. A full-length standing AP radiograph reveals the Mechanical Axis Deviation (MAD) is significantly medial to the knee joint center. The mechanical Lateral Distal Femoral Angle (mLDFA) is 88 degrees (normal 87-89 deg), and the Medial Proximal Tibial Angle (MPTA) is 79 degrees (normal 85-90 deg). What is the primary source of the varus deformity?

. Distal femur
. Knee joint line convergence (ligamentous laxity)
. Proximal tibia
. Femoral neck-shaft angle
. Ankle mortise

Correct Answer & Explanation

. Proximal tibia

Explanation

The malalignment test identifies the source of deviation. Here, the mLDFA is normal, indicating the femur is not the primary source. The MPTA is abnormally low (<85 degrees), confirming the varus deformity originates in the proximal tibia.

Question 12665

Topic: 2. Trauma

A 16-year-old female presents with a 4 cm femur length discrepancy. You plan to perform "lengthening over a nail" (LON). What is the primary theoretical advantage of this technique compared to classic Ilizarov external fixation alone, and what is its most feared complication?

. Advantage: Lower cost; Complication: Nonunion.
. Advantage: Reduced time in the external fixator; Complication: Deep intramedullary infection.
. Advantage: Allows immediate full weight-bearing; Complication: Premature consolidation.
. Advantage: Avoids the need for an osteotomy; Complication: Hardware failure.
. Advantage: Greater maximum length achieved; Complication: Fat embolism.

Correct Answer & Explanation

. Advantage: Reduced time in the external fixator; Complication: Deep intramedullary infection.

Explanation

Lengthening over a nail (LON) allows the external fixator to be removed immediately after the distraction phase, as the intramedullary nail supports the regenerate bone during the consolidation phase. The most significant risk is deep intramedullary infection, as pin tract infections can track down to the nail.

Question 12666

Topic: 2. Trauma

A 24-year-old female presents with severe lateral compartment knee pain and a valgus deformity. The mechanical axis passes through the lateral compartment, and the deformity is localized to the distal femur (abnormal mLDFA). You decide to perform a lateral opening-wedge distal femoral osteotomy. How will this specific procedure affect the patient's limb length?

. It will decrease the limb length.
. It will have no effect on limb length.
. It will increase the limb length.
. It will decrease limb length only if the hinge fractures.
. It will randomly increase or decrease length depending on the plate used.

Correct Answer & Explanation

. It will increase the limb length.

Explanation

A lateral opening-wedge distal femoral osteotomy adds bone graft/void filler to the lateral aspect of the femur, thereby increasing the overall length of the limb. In contrast, a medial closing-wedge osteotomy would decrease limb length.

Question 12667

Topic: Lower Extremity Trauma

A 10-year-old boy is undergoing femoral lengthening with an external fixator. Radiographs at 4 weeks demonstrate rigid bridging bone across the distraction gap, preventing further mechanical lengthening despite turning the struts. What is the most appropriate management for this premature consolidation?

. Dramatically increase the distraction rate to 3.0 mm per day
. Administer high-dose non-steroidal anti-inflammatory drugs (NSAIDs)
. Remove the external fixator and switch to a locked intramedullary nail
. Perform extracorporeal shockwave therapy (ESWT) over the regenerate
. Take the patient back to the operating room to repeat the corticotomy

Correct Answer & Explanation

. Take the patient back to the operating room to repeat the corticotomy

Explanation

Premature consolidation occurs when the bone heals faster than the distraction rate. If mechanical manipulation (osteoclasis) fails or bridging is advanced, a repeat surgical corticotomy is required to resume lengthening.

Question 12668

Topic: 2. Trauma

In the correction of complex lower limb deformities using a Taylor Spatial Frame (TSF), a 'residual' program is sometimes required. What is the most common clinical reason for needing a residual TSF program?

. Hardware failure of the struts
. Inaccuracy in initial mounting parameters or changes during the treatment phase
. Nonunion at the osteotomy site
. Premature consolidation of the regenerate
. Deep vein thrombosis preventing strut adjustments

Correct Answer & Explanation

. Inaccuracy in initial mounting parameters or changes during the treatment phase

Explanation

The TSF relies on precise input of mounting parameters. Inaccuracies in measuring these parameters, or dynamic shifts of the reference fragments during treatment, often require running a 'residual' program to recalculate and achieve final precise correction.

Question 12669

Topic: 2. Trauma

A 14-year-old boy is scheduled for femoral lengthening over an intramedullary nail (LON). Compared to classic circular external fixation alone, what is the primary advantage of the LON technique?

. Decreased risk of deep intramedullary infection
. Elimination of the need for an osteotomy
. Significantly reduced time wearing the external fixator
. Ability to correct large rotational deformities dynamically
. Elimination of the latency period prior to distraction

Correct Answer & Explanation

. Significantly reduced time wearing the external fixator

Explanation

Lengthening over a nail (LON) allows the external fixator to be removed immediately after the distraction phase is completed, as the internal nail supports the regenerate. This drastically reduces the external fixation index (time the patient spends in the frame).

Question 12670

Topic: 2. Trauma



When evaluating a deformity using the mechanical axis planning method, where is the Center of Rotation of Angulation (CORA) physically located on the radiograph?

. At the point of maximum clinical bow of the diaphysis.
. At the intersection of the proximal and distal mechanical axes of the deformed bone segment.
. Always exactly centered at the articular joint line.
. At the level of the previous fracture site or scar.
. At the intersection of the anatomical axis and the transverse joint line.

Correct Answer & Explanation

. At the intersection of the proximal and distal mechanical axes of the deformed bone segment.

Explanation

The CORA is geometrically defined as the specific point where the proximal mechanical axis line and the distal mechanical axis line of the deformed bone intersect.

Question 12671

Topic: 2. Trauma

A 30-year-old woman sustains a closed, displaced midshaft humerus fracture after a fall. On initial examination, she is unable to actively extend her wrist or fingers. Sensation is decreased over the dorsal aspect of the first web space. Which of the following is the most appropriate initial management for this specific neurological deficit?

. Immediate surgical exploration of the nerve
. Electromyography (EMG) and nerve conduction studies
. Observation and supportive splinting
. Magnetic resonance imaging (MRI) of the humerus
. Administration of high-dose intravenous corticosteroids

Correct Answer & Explanation

. Observation and supportive splinting

Explanation

Correct Answer: Observation and supportive splintingThe patient has a radial nerve palsy, which is the most common neurological injury associated with midshaft humerus fractures. In the setting of a closed fracture, the vast majority of these injuries are neuropraxias that will resolve spontaneously over 3 to 4 months. The standard of care is observation and supportive splinting (e.g., a wrist extension splint) to prevent contractures. Immediate exploration is generally reserved for open fractures, penetrating trauma, or palsies that develop after closed reduction.

Question 12672

Topic: 2. Trauma

A 24-year-old man falls on an outstretched hand and presents with anatomic snuffbox tenderness. Radiographs reveal a non-displaced fracture through the waist of the scaphoid. He is placed in a thumb spica cast. The high risk of avascular necrosis and nonunion in this fracture pattern is primarily due to the retrograde blood supply to the proximal pole. Which of the following vessels provides this critical blood supply?

. Anterior interosseous artery
. Posterior interosseous artery
. Ulnar artery
. Dorsal carpal branch of the radial artery
. Superficial palmar arch

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

Correct Answer: Dorsal carpal branch of the radial arteryThe scaphoid has a precarious retrograde blood supply. The primary blood supply enters the distal pole of the scaphoid via branches of the radial artery, specifically the dorsal carpal branch, and flows proximally. A fracture through the waist of the scaphoid can disrupt this retrograde flow, leaving the proximal pole ischemic and at high risk for avascular necrosis and nonunion.

Question 12673

Topic: 2. Trauma

A 22-year-old male sustains a proximal pole scaphoid fracture. The high risk of avascular necrosis and nonunion in this specific region is primarily due to the retrograde intraosseous blood supply derived from branches of which of the following arteries?

. Ulnar artery
. Anterior interosseous artery
. Radial artery
. Deep palmar arch
. Superficial palmar arch

Correct Answer & Explanation

. Radial artery

Explanation

Correct Answer: Radial arteryThe scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery. The blood vessels enter the scaphoid at the dorsal ridge near the waist and supply the bone in a retrograde fashion (from distal to proximal). Because of this retrograde flow, fractures at the proximal pole of the scaphoid frequently disrupt the blood supply to the proximal fragment, leading to a high incidence of avascular necrosis and nonunion.

Question 12674

Topic: 2. Trauma
A 28-year-old farmer sustains a highly contaminated open tibial shaft fracture with extensive soft tissue stripping and a 12 cm laceration after a tractor accident. According to classic evidence-based guidelines, which of the following intravenous antibiotic regimens is most appropriate for initial management?
. First-generation cephalosporin alone
. First-generation cephalosporin and an aminoglycoside
. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin
. Third-generation cephalosporin alone
. Vancomycin alone

Correct Answer & Explanation

. First-generation cephalosporin, an aminoglycoside, and high-dose penicillin

Explanation

This is a Gustilo-Anderson Type III open fracture with heavy farm/soil contamination. Standard protocol for Type I and II open fractures includes a first-generation cephalosporin (e.g., cefazolin). For Type III fractures, an aminoglycoside (e.g., gentamicin) is added for expanded Gram-negative coverage. When there is farm, soil, or standing water contamination, high-dose penicillin is classically added to cover anaerobic organisms, specifically Clostridium species, to prevent gas gangrene.

Question 12675

Topic: 2. Trauma

A 6-year-old boy sustains a severe extension-type supracondylar humerus fracture. He subsequently develops untreated compartment syndrome leading to Volkmann's ischemic contracture. Which of the following muscle groups in the forearm is typically the most severely affected by this ischemic process?

. Flexor carpi ulnaris and flexor digitorum superficialis
. Extensor digitorum communis and extensor carpi radialis brevis
. Flexor digitorum profundus and flexor pollicis longus
. Pronator teres and flexor carpi radialis
. Brachioradialis and supinator

Correct Answer & Explanation

. Flexor digitorum profundus and flexor pollicis longus

Explanation

Correct Answer: CVolkmann's ischemic contracture most severely affects the deep volar compartment of the forearm. The flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) are the most profoundly affected muscles due to their central location and reliance on the anterior interosseous artery, which is highly susceptible to ischemic compromise during severe swelling.

Question 12676

Topic: 2. Trauma
A 45-year-old farmer sustains a highly contaminated open tibial shaft fracture after his leg is caught in a tractor mechanism (Gustilo-Anderson Type III). In addition to immediate surgical debridement and a first-generation cephalosporin, which of the following antibiotic regimens is most appropriate to add for this specific injury profile?
. Vancomycin only
. Gentamicin and Penicillin
. Clindamycin only
. Metronidazole only
. Ciprofloxacin only

Correct Answer & Explanation

. Gentamicin and Penicillin

Explanation

For a Gustilo-Anderson Type III open fracture, broad-spectrum coverage including a first-generation cephalosporin and an aminoglycoside (like gentamicin) or a third-generation cephalosporin is standard to cover Gram-positive and Gram-negative organisms. Because this is a farm injury with gross soil/fecal contamination, there is a high risk of Clostridium infection, necessitating the addition of Penicillin.

Question 12677

Topic: 2. Trauma

A 6-year-old boy sustains a severe extension-type supracondylar humerus fracture. Despite closed reduction and percutaneous pinning, he develops unrecognized compartment syndrome leading to Volkmann's ischemic contracture. Which of the following muscle groups is typically the most severely affected by the ischemic necrosis in this condition?

. Flexor carpi ulnaris and flexor carpi radialis
. Flexor digitorum profundus and flexor pollicis longus
. Extensor digitorum communis and extensor indicis
. Pronator teres and flexor digitorum superficialis
. Brachioradialis and supinator

Correct Answer & Explanation

. Flexor digitorum profundus and flexor pollicis longus

Explanation

Correct Answer: BVolkmann's ischemic contracture is the classic sequela of untreated compartment syndrome in the forearm, often following supracondylar humerus fractures. The deep volar compartment is the most susceptible to ischemia due to its central location and vascular supply pattern. Consequently, the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL) are the most severely affected muscles, leading to the characteristic flexion deformities of the fingers and thumb.

Question 12678

Topic: 2. Trauma

A 22-year-old male falls on an outstretched hand and sustains a non-displaced fracture of the proximal pole of the scaphoid. He is at a high risk for avascular necrosis (AVN) and nonunion. This risk is primarily due to the scaphoid's retrograde blood supply, which predominantly enters the bone at which of the following anatomical locations?

. Volar tubercle
. Proximal pole articular surface
. Dorsal ridge
. Scapholunate interosseous ligament insertion
. Distal articular surface

Correct Answer & Explanation

. Dorsal ridge

Explanation

Correct Answer: CThe scaphoid has a tenuous, retrograde blood supply. The major blood supply (70-80%) comes from branches of the radial artery that enter the bone at the dorsal ridge (distal to the waist) and flow proximally. Because of this retrograde flow, fractures at the waist or proximal pole disrupt the blood supply to the proximal fragment, significantly increasing the risk of avascular necrosis and nonunion.

Question 12679

Topic: 2. Trauma

In an adult patient sustaining a displaced intracapsular femoral neck fracture, the primary blood supply to the femoral head is severely compromised. Which of the following vessels provides the majority of the arterial supply to the adult weight-bearing dome of the femoral head?

. Artery of the ligamentum teres
. Lateral epiphyseal branches of the medial circumflex femoral artery
. Inferior metaphyseal branches of the lateral circumflex femoral artery
. Ascending branch of the inferior gluteal artery
. Descending branch of the superior gluteal artery

Correct Answer & Explanation

. Lateral epiphyseal branches of the medial circumflex femoral artery

Explanation

Correct Answer: BIn adults, the primary blood supply to the femoral head comes from the medial circumflex femoral artery (MCFA). The MCFA gives rise to the lateral epiphyseal arteries (also known as the posterosuperior retinacular vessels), which penetrate the capsule and supply the majority of the weight-bearing dome of the femoral head. The artery of the ligamentum teres (derived from the obturator artery) provides a negligible supply in adults, making the head highly susceptible to avascular necrosis following a displaced femoral neck fracture.

Question 12680

Topic: 2. Trauma

Volkmann's ischemic contracture is a feared complication of supracondylar humerus fractures in children. Which of the following muscle groups is most susceptible to the initial ischemic insult in this condition?

. Superficial extensors of the forearm
. Deep flexors of the forearm
. Intrinsic muscles of the hand
. Biceps brachii and brachialis
. Pronator teres and flexor carpi radialis

Correct Answer & Explanation

. Deep flexors of the forearm

Explanation

Correct Answer: Deep flexors of the forearmVolkmann's contracture results from untreated compartment syndrome of the forearm, typically following brachial artery compromise. The deep flexor compartment, specifically the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL), is the most severely affected due to its central location and vulnerability to ischemia.

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