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2. Trauma MCQs

Practice Set 170 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 3381

Topic: 2. Trauma

What is the most widely accepted standard rate and rhythm for distraction osteogenesis in a healthy young patient undergoing tibial lengthening?

. 0.25 mm four times a day
. 1.0 mm once a day
. 2.0 mm twice a day
. 0.5 mm twice a day
. 1.5 mm three times a day

Correct Answer & Explanation

. 0.25 mm four times a day

Explanation

The optimal rate is generally 1.0 mm per day, divided into frequent, smaller increments (e.g., 0.25 mm four times daily). This rhythm provides a steady mechanical stimulus for bone formation and minimizes soft-tissue trauma.

Question 3382

Topic: Lower Extremity Trauma

When evaluating a patient for a high tibial osteotomy to address a sagittal plane deformity, what is the normal posterior proximal tibial angle (PPTA)?

. 75 degrees
. 81 degrees
. 88 degrees
. 95 degrees
. 105 degrees

Correct Answer & Explanation

. 81 degrees

Explanation

The normal posterior proximal tibial angle (PPTA) is approximately 81 degrees. This corresponds to the normal 9-degree posterior slope of the tibial plateau.

Question 3383

Topic: Lower Extremity Trauma

In the sagittal plane, the mechanical axis of the lower extremity connects the center of the femoral head to the center of the ankle. Where does this normal mechanical axis pass in relation to the knee joint?

. Through the posterior third of the distal femur
. Exactly through or slightly anterior to the center of the knee joint
. Anterior to the patella
. Through the tibial tubercle
. Through the posterior cortex of the proximal tibia

Correct Answer & Explanation

. Exactly through or slightly anterior to the center of the knee joint

Explanation

In a normal lower limb, the sagittal mechanical axis passes through or slightly anterior to the center of the knee joint, creating an extension moment during weight-bearing.

Question 3384

Topic: 2. Trauma

Preoperative planning for a tibial malunion reveals a deformity present in both the coronal and sagittal planes. The AP radiograph demonstrates a 15-degree varus deformity, and the lateral radiograph demonstrates a 20-degree procurvatum deformity. Utilizing the trigonometric method for oblique plane deformities, what is the approximate magnitude of the maximum true deformity angle?

. 15 degrees
. 20 degrees
. 25 degrees
. 35 degrees
. 40 degrees

Correct Answer & Explanation

. 25 degrees

Explanation

The true magnitude of an oblique plane deformity is calculated using the Pythagorean theorem: square root of (x^2 + y^2). The square root of (15^2 + 20^2) equals the square root of 625, which is exactly 25 degrees.

Question 3385

Topic: 2. Trauma

The Anatomic-Mechanical Angle (AMA) of the femur normally averages 7 degrees and is used to guide intraoperative alignment during intramedullary nailing of distal femur fractures. According to Paley's principles, in which of the following patient populations is the AMA angle typically significantly increased (e.g., 9-11 degrees)?

. Patients with exceptionally long femurs.
. Patients with narrow pelvic widths.
. Patients with short stature and short femurs.
. Patients with coxa valga.
. Patients with severe genu recurvatum.

Correct Answer & Explanation

. Patients with short stature and short femurs.

Explanation

The AMA angle depends on pelvic width and femoral length. A wider pelvis or a shorter femur geometry increases the angular divergence between the anatomical and mechanical axes, resulting in a larger AMA angle.

Question 3386

Topic: 2. Trauma

A 70-year-old patient with severe osteoarthritis and a history of femoral malunion requires precise deformity correction. The ultimate goal of achieving the 'knee forward position' for a true AP standing radiograph, as described by Paley's principles, is to:

. A. Minimize radiation exposure to the patient by reducing the number of repeat images.
. B. Ensure the patient is comfortable and stable during the imaging process.
. C. Accurately measure coronal plane alignment and joint orientation angles by ensuring the knee's frontal plane is orthogonal to the X-ray beam.
. D. Facilitate easier identification of the fibular head and its relationship to the tibia.
. E. Standardize the imaging technique across different radiology departments for administrative purposes.

Correct Answer & Explanation

. C. Accurately measure coronal plane alignment and joint orientation angles by ensuring the knee's frontal plane is orthogonal to the X-ray beam.

Explanation

Correct Answer: CThe text states: "The gold standard for a true AP view is theknee forward position... When this is achieved, the knee forward plane is, by definition, the true frontal plane of the knee joint, allowing for accurate measurement of alignment and joint orientation." The goal is to ensure the frontal plane of the knee is perfectly parallel to the imaging cassette (orthogonal to the X-ray beam) to avoid projection errors and obtain accurate measurements for planning.Incorrect Options:A. Minimize radiation exposure to the patient by reducing the number of repeat images:While accurate initial imaging can reduce repeats, this is a secondary benefit, not theultimate goalof the specific positioning technique for measurement accuracy.B. Ensure the patient is comfortable and stable during the imaging process:Patient comfort and stability are important for any imaging, but the 'knee forward position' is a technical requirement for accuracy, not primarily for comfort.D. Facilitate easier identification of the fibular head and its relationship to the tibia:While rotational alignment affects the appearance of these structures, the ultimate goal is broader: accurate measurement of overall limb alignment and joint angles, not just specific bony landmarks.E. Standardize the imaging technique across different radiology departments for administrative purposes:Standardization is a positive outcome, but thereasonfor standardization is to achieve the accuracy required for surgical planning, which is the ultimate goal.

Question 3387

Topic: 2. Trauma

A 35-year-old male presents with a progressive genu varum deformity following a tibial shaft fracture that healed with 10 degrees of varus angulation. His knee joint lines appear parallel and well-preserved on full-length standing radiographs, with no evidence of significant cartilage loss or ligamentous laxity.

Based on Paley's principles, this patient's presentation most accurately describes which of the following?

. Malorientation with secondary malalignment.
. A purely intra-articular deformity.
. Malalignment with normally oriented joints.
. A primary malorientation requiring a joint-preserving osteotomy at the knee.
. A complex multi-planar deformity requiring external fixation.

Correct Answer & Explanation

. Malalignment with normally oriented joints.

Explanation

Correct Answer: CThe case defines malalignment as a deviation of the limb's overall mechanical axis, and states that 'A patient can have perfectly straight bones but still present with severe varus malalignment due to joint line issues (such as ligamentous laxity or cartilage loss).' Conversely, it notes that a limb can be malaligned with normally oriented joints, indicating a purely diaphyseal, mid-shaft deformity. In this vignette, the tibial shaft fracture healed with varus angulation (a diaphyseal issue), but the knee joint lines are parallel and well-preserved (normally oriented joints). Therefore, the patient has a deviation of the overall mechanical axis (malalignment) caused by a bone deformity, but the joint surfaces themselves are correctly oriented relative to their respective bones.

Question 3388

Topic: Lower Extremity Trauma

A 16-year-old female presents with a valgus deformity of her left knee. A full-length standing radiograph is obtained:

Analysis reveals a normal femoral shaft mechanical axis but an abnormally angled lateral distal femoral condyle, leading to a valgus mechanical axis deviation.

This patient's deformity is best characterized as:

. A purely diaphyseal malalignment.
. Malalignment with normally oriented joints.
. A primary malorientation driving secondary malalignment.
. An isolated ligamentous laxity causing valgus instability.
. A complex multi-planar deformity requiring a proximal tibial osteotomy.

Correct Answer & Explanation

. A primary malorientation driving secondary malalignment.

Explanation

Correct Answer: CThe vignette describes a situation where the femoral shaft itself is straight (normal femoral shaft mechanical axis), but the joint surface (abnormally angled lateral distal femoral condyle) is tilted. This abnormal angulation of the joint surface relative to its own bone's axis is the definition of malorientation. This malorientation then causes the overall limb's mechanical axis to deviate (valgus mechanical axis deviation), which is malalignment. The case emphasizes that 'if the joint surface is "tilted" or dysplastic, the entire limb will be driven into malalignment.' Therefore, it is a primary malorientation leading to secondary malalignment. Option A is incorrect because the shaft is normal. Option B is incorrect because the joint is maloriented. Option D is not supported by the information provided. Option E is incorrect as the primary issue is femoral malorientation, not tibial, and the complexity is defined by the malorientation/malalignment distinction.

Question 3389

Topic: Lower Extremity Trauma

Radiographic evaluation of a varus knee deformity reveals a mechanical axis deviation (MAD) of 40 mm medial to the center of the knee. The mechanical lateral distal femoral angle (mLDFA) is 87 degrees, and the medial proximal tibial angle (MPTA) is 80 degrees. Based on this Malalignment Test, where is the primary source of the deformity?

. Proximal femur
. Distal femur
. Proximal tibia
. Distal tibia
. Intra-articular knee joint

Correct Answer & Explanation

. Proximal tibia

Explanation

The normal mLDFA is 85-90 degrees, and normal MPTA is 85-90 degrees. An MPTA of 80 degrees indicates proximal tibial varus, localizing the primary deformity to the proximal tibia.

Question 3390

Topic: Lower Extremity Trauma

A 35-year-old male presents with genu valgum. The Mechanical Axis Deviation (MAD) is lateral to the knee center. The mLDFA is 82 degrees, MPTA is 87 degrees, and JLCA is 2 degrees. According to Paley's malalignment test, what is the location of the deformity?

. Proximal tibia
. Distal femur
. Knee joint (ligamentous)
. Proximal femur
. Distal tibia

Correct Answer & Explanation

. Distal femur

Explanation

An mLDFA of 82 degrees is below the normal range (85-90), indicating valgus deformity in the distal femur. The normal MPTA and JLCA rule out the tibia and intra-articular sources.

Question 3391

Topic: 2. Trauma

A 22-year-old sustains a malunited distal tibia fracture. The lateral distal tibial angle (LDTA) is measured to plan a supramalleolar osteotomy. What is the normal average value of the LDTA?

. 80 degrees
. 85 degrees
. 89 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 89 degrees

Explanation

The normal average lateral distal tibial angle (LDTA) is 89 degrees, with an acceptable range of 86 to 92 degrees.

Question 3392

Topic: Lower Extremity Trauma

A patient with an apex anterior (procurvatum) deformity of the distal femur is planned for correction. Which of the following radiographic angles is utilized to assess the sagittal plane alignment of the distal femur?

. Posterior proximal femoral angle (PPFA)
. Posterior distal femoral angle (PDFA)
. Anterior distal tibial angle (ADTA)
. Proximal posterior tibial angle (PPTA)
. Mechanical lateral distal femoral angle (mLDFA)

Correct Answer & Explanation

. Posterior distal femoral angle (PDFA)

Explanation

Sagittal alignment of the distal femur is assessed using the posterior distal femoral angle (PDFA), which normally averages 83 degrees.

Question 3393

Topic: Lower Extremity Trauma

A patient undergoes radiographic analysis for genu valgum. The mechanical lateral distal femoral angle (mLDFA) is calculated. Which of the following values definitively indicates a femoral valgus deformity?

. 95 degrees
. 87 degrees
. 81 degrees
. 100 degrees
. 89 degrees

Correct Answer & Explanation

. 87 degrees

Explanation

The normal mLDFA is approximately 87 degrees (range 85-90 degrees). An angle less than 85 degrees indicates a valgus deformity of the distal femur, whereas an angle greater than 90 indicates varus.

Question 3394

Topic: 2. Trauma

A 35-year-old male with a history of a proximal tibia fracture presents with progressive knee varus. Radiographic analysis reveals an mLDFA of 88 degrees and an mMPTA of 75 degrees. Where is the primary source of the deformity?

. Distal femur
. Intra-articular knee joint
. Proximal tibia
. Midshaft tibia
. Distal tibia

Correct Answer & Explanation

. Proximal tibia

Explanation

The normal mMPTA is approximately 87 degrees. An mMPTA of 75 degrees indicates a significant proximal tibial varus deformity. The normal mLDFA (88 degrees) rules out a primary femoral contribution.

Question 3395

Topic: Lower Extremity Trauma

A patient requires a multiplanar deformity correction of the tibia. A lateral radiograph is obtained to measure the posterior proximal tibial angle (PPTA). What is the normal average PPTA used as a reference in Paley's analysis?

. 81 degrees
. 87 degrees
. 90 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 81 degrees

Explanation

The normal posterior proximal tibial angle (PPTA) is approximately 81 degrees. This reflects the normal posterior slope of the tibial plateau, which is roughly 9 degrees relative to the perpendicular of the anatomic axis.

Question 3396

Topic: 2. Trauma
A 23-year-old man is injured in a motorcycle accident and has a Glasgow Coma Scale (GCS) score of 10. His fiance arrives shortly after he does. He has an open, IIIc tibial fracture. The patient's parents are on the way but are not expected to arrive for some time. Who should be asked to provide informed consent?
. The patient
. The fiance
. The surgeon performing the procedure along with another physician with similar experience and knowledge
. The surgeon performing the procedure and a nurse taking care of the patient
. Wait for the patient's parents to arrive and have them provide informed consent

Correct Answer & Explanation

. The surgeon performing the procedure along with another physician with similar experience and knowledge

Explanation

With a GCS of 10, the patient is not capable of providing consent nor does the fiance have legal standing to do so. This is an emergency and waiting for the parents is not acceptable. Two surgeons of similar knowledge and experience may confirm the necessity of the procedure.

Question 3397

Topic: 2. Trauma
A 33-year-old man had his foot run over by a forklift 1 hour ago. Examination reveals that the head of the fifth metatarsal is extruded through the plantar aspect of the foot. The foot is severely swollen and pale, there is no sensation in the toes, and the pulses are not palpable. Radiographs are shown in Figures 42a and 42b. Emergent management should consist of
. immediate transmetatarsal amputation.
. immediate below-knee amputation.
. application of a splint and observation.
. fasciotomy and fracture fixation.
. fasciotomy without fracture fixation.

Correct Answer & Explanation

. fasciotomy and fracture fixation.

Explanation

DISCUSSION: Following a severe crush injury, the patient has an acute compartment syndrome. Even though there is an open fracture, this is not sufficient to decompress the compartment syndrome. Therefore, splinting and observation are not appropriate. The surgical treatment of choice is fasciotomy with fixation of the multiple fractures. A primary amputation is not indicated because there is potential for salvage of this devastating injury. REFERENCES: Fakhouri AJ, Manoli A II: Acute foot compartment syndromes. J Orthop Trauma 1992;6:223-228. Myerson MS: Management of compartment syndromes of the foot. Clin Orthop 1991;271:239-248. Ziv I, Mosheiff R, Zeligowski A, Liebergal M, Lowe J, Segal D: Crush injuries of the foot with compartment syndrome: Immediate one-stage management. Foot Ankle 1989;9:185-189.

Question 3398

Topic: 2. Trauma
A 13-year-old girl was riding on an all-terrain vehicle when the driver struck a tree. She sustained the injury shown in Figures 45a through 45d. This injury is best described as what type of acetabular fracture pattern?
. T-type
. Anterior column
. Both-column
. Anterior column posterior hemitransverse
. Posterior column

Correct Answer & Explanation

. Both-column

Explanation

DISCUSSION: The fracture is a both-column fracture in the Judet/Letournel classification and a C3 in the AO classification. There is extension into the sacroiliac joint along the pelvic brim and comminution along the posterior column above the sciatic notch. Both the anterior and posterior columns are separately broken and displaced. However, the defining feature of a both-column pattern, as seen in this patient, is that all articular fragments are on fracture fragments and no joint surface is left intact to the axial skeleton above. The use of three-dimensional images makes it easier to view the location of the fracture fragments and the amount and direction of displacement. REFERENCES: Helfet DL, Beck M, Gautier E, et al: Surgical techniques for acetabular fractures, in Tile M, Helfet DL, Kellam JF (eds): Fractures of the Pelvis and Acetabulum. Philadelphia, PA, Lippincott Williams & Wilkins, 2003, pp 533-603. Tile M: Describing the injury: Classification of acetabular fractures, in Tile M, Helfet DL, Kellam JF (eds): Fractures of the Pelvis and Acetabulum, ed 3. Philadelphia, PA, Lippincott Williams & Wilkins, 2003, pp 427-475. Brandser E, Marsh JL: Acetabular fractures: Easier classification with a systematic approach. Am J Roentgenol 1998;171:1217-1228.

Question 3399

Topic: 2. Trauma
  • Which of the following advantages does the use of a vascularized fibula graft have over a nonvascularized fibula graft?
. Begins to remodel and hypertrophy more quickly
. Provides a better scaffold for osteoconduction
. Reduces the risk of early fracture
. Reduces technical difficulty
. Lowers donor site morbidity

Correct Answer & Explanation

. Begins to remodel and hypertrophy more quickly

Explanation

A vascularized fibula graft, because its osteogenic potential remains unhampered by loss of vascularity it will begin to remodel and hypertrophy more quickly. Both types of grafts would act equivocably as scaffolding for osteoconduction. Early risk of fracture is increased if the nonvascularized fibula graft is over 12 centimeters in length as compared to a vascularized graft.And a vascularized graft requires greater technical skills and a larger dissection to isolate the vascular pedicle with associated increased donor site morbidity.

Question 3400

Topic: 2. Trauma
Which of the following is considered a contraindication to functional bracing for the treatment of humeral shaft fractures?
. A closed midshaft fracture accompanied by a radial nerve palsy prior to an attempt at reduction
. A fracture with more than 30 degrees of varus angulation prior to reduction
. A distal one third spiral fracture
. A fracture caused by a low-velocity hand gun treated initially with wound debridement and antibiotics
. An inability to maintain less than 30 degrees of varus and 20 degrees of anterior or posterior angulation after reduction

Correct Answer & Explanation

. An inability to maintain less than 30 degrees of varus and 20 degrees of anterior or posterior angulation after reduction

Explanation

DISCUSSION: Most closed humeral shaft fractures and fractures caused by a low-velocity hand gun can be managed nonsurgically with closed reduction and application of a coaptation splint followed by a functional brace. Contraindications to use of the functional brace include: 1) massive soft-tissue or bone loss; 2) an unreliable or noncompliant patient; and 3) an inability to maintain acceptable fracture alignment of up to 20 degrees of anterior or posterior angulation, 30 degrees of varus or valgus angulation, and greater than 3 cm of shortening. REFERENCES: Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 271-286. Pollock FH, Drake D, Bovill EG, Day L, Trafton PG: Treatment of radial neuropathy associated with fractures of the humerus. J Bone Joint Surg Am 1981;63:239-243. Sarmiento A, Zagorski JB, Zych GA, et al: Functional bracing for the treatment of fractures of the humeral diaphysis. J Bone Joint Surg Am 2000;82:478-486.

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