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2. Trauma MCQs

Practice Set 145 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 2881

Topic: 2. Trauma

What is the most common long-term complication following operative management of a terrible triad injury?

. Ulnar neuropathy
. Post-traumatic stiffness (loss of motion)
. Recurrent chronic instability
. Heterotopic ossification requiring excision
. Nonunion of the coronoid

Correct Answer & Explanation

. Post-traumatic stiffness (loss of motion)

Explanation

Post-traumatic elbow stiffness, particularly loss of terminal extension, is the most common complication following the surgical treatment of terrible triad injuries. Early, stable fixation allowing for immediate range of motion is critical to minimize this.

Question 2882

Topic: 2. Trauma
According to the Bado classification, a fracture of the ulnar diaphysis with lateral dislocation of the radial head is classified as which type?
. Bado Type I
. Bado Type II
. Bado Type III
. Bado Type IV
. Monteggia equivalent

Correct Answer & Explanation

. Bado Type III

Explanation

A Bado Type III Monteggia fracture is characterized by a metaphyseal fracture of the ulna with a lateral dislocation of the radial head. It is most commonly seen in pediatric patients.

Question 2883

Topic: 2. Trauma
A patient presents with an anterior elbow dislocation, a comminuted radial head fracture, and a diaphyseal fracture of both the radius and the ulna. Based on the classification of fracture-dislocations of the forearm, how is this injury categorized?
. Bado Type I
. Bado Type II
. Bado Type III
. Bado Type IV
. Terrible Triad equivalent

Correct Answer & Explanation

. Bado Type IV

Explanation

Bado Type IV Monteggia fractures are characterized by fractures of both the radius and ulna shafts accompanied by an anterior dislocation of the radial head.

Question 2884

Topic: 2. Trauma
A 32-year-old female presents with a Bado Type I Monteggia fracture-dislocation. She exhibits an inability to actively extend her thumb and fingers at the metacarpophalangeal joints, though wrist extension is preserved with radial deviation. Which nerve is most likely injured?
. Anterior interosseous nerve
. Posterior interosseous nerve (PIN)
. Ulnar nerve
. Superficial radial nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Posterior interosseous nerve (PIN)

Explanation

The PIN is the most commonly injured nerve in Bado Type I and III Monteggia fractures due to anterior or lateral radial head dislocation tethering the nerve. It typically presents as a neurapraxia with spontaneous recovery expected.

Question 2885

Topic: 2. Trauma

To mitigate the high risk of heterotopic ossification following operative management of a terrible triad injury, what is the most appropriate pharmacological prophylaxis?

. Low-molecular-weight heparin for 14 days
. Indomethacin for 3 to 6 weeks
. Aspirin 81 mg daily for 2 weeks
. Alendronate for 6 months
. High-dose oral corticosteroids

Correct Answer & Explanation

. Indomethacin for 3 to 6 weeks

Explanation

Indomethacin (a nonsteroidal anti-inflammatory drug) is frequently utilized as prophylaxis against heterotopic ossification following severe elbow trauma. Radiation therapy is another prophylactic option.

Question 2886

Topic: 2. Trauma

In the surgical treatment of an adult with a Bado Type I Monteggia fracture, which surface of the ulna provides the best biomechanical position for plate placement to utilize the tension band principle?

. Anterior surface
. Posterior surface
. Medial surface
. Volar surface
. Lateral surface

Correct Answer & Explanation

. Posterior surface

Explanation

The posterior surface of the ulna is the tension side. Placing the plate posteriorly utilizes the tension band principle, providing the most biomechanically stable fixation.

Question 2887

Topic: Upper Extremity Trauma

The coronoid process acts as the primary bony constraint to which of the following forces in the elbow joint?

. Varus stress
. Posterior translation of the ulna
. Anterior translation of the radius
. Distraction of the radiocapitellar joint
. Proximal migration of the radius

Correct Answer & Explanation

. Posterior translation of the ulna

Explanation

The coronoid is the primary bony restraint against posterior translation of the ulna relative to the distal humerus, acting as an anterior buttress. It also provides significant stability against varus stress via its anteromedial facet.

Question 2888

Topic: Upper Extremity Trauma

During the postoperative rehabilitation of a successfully reconstructed terrible triad injury (coronoid, radial head, and LCL repaired), immediate active-assisted range of motion is initiated. To maximally protect the LCL repair during elbow flexion and extension, the forearm should be held in what position?

. Full supination
. Full pronation
. Neutral rotation
. Alternating pronation and supination
. Forced valgus

Correct Answer & Explanation

. Full pronation

Explanation

Pronation of the forearm positions the intact or repaired medial structures to act as a hinge, relaxing the LCL complex and protecting the lateral repair from varus stress during early range of motion.

Question 2889

Topic: 2. Trauma

The accepted mechanism of injury for a Bado Type I Monteggia fracture is most commonly associated with:

. A direct blow to the posterior aspect of the forearm
. Hyperpronation of the forearm during a fall on an outstretched hand
. Hypersupination combined with an axial load
. An isolated extreme valgus force to the elbow
. Avulsion by the biceps tendon during forceful eccentric contraction

Correct Answer & Explanation

. Hyperpronation of the forearm during a fall on an outstretched hand

Explanation

The most widely accepted mechanism for Bado Type I (anterior) injuries is forced hyperpronation during a fall on an outstretched hand, which leverages the radius anteriorly while fracturing the ulna.

Question 2890

Topic: 2. Trauma

In the setting of a terrible triad injury, if a Type 1 (tip) coronoid fracture is deemed too small for screw fixation or a plate, what is the most appropriate surgical technique to stabilize it?

. Excision of the fragment and isolated LCL repair
. Lasso suture technique capturing the anterior capsule and coronoid tip
. Transarticular K-wire fixation across the ulnohumeral joint
. Resection and reconstruction with a triceps tendon autograft
. Application of a hinged external fixator without addressing the coronoid

Correct Answer & Explanation

. Lasso suture technique capturing the anterior capsule and coronoid tip

Explanation

For small, comminuted, or unfixable coronoid tip fractures, a suture lasso technique through the anterior capsule, passed through drill holes in the proximal ulna, effectively restores anterior stability.

Question 2891

Topic: Lower Extremity Trauma

A resident is performing a Mechanical Axis Test (MAT) on a long-leg radiograph to assess a patient's frontal plane alignment. After drawing the necessary lines, they are measuring the orientation of the distal femur.

Which of the following represents the *normal* range for the Mechanical Lateral Distal Femoral Angle (mLDFA)?

. 80°–85°
. 85°–90°
. 90°–95°
. 75°–80°
. 95°–100°

Correct Answer & Explanation

. 85°–90°

Explanation

Correct Answer: BThe Mechanical Lateral Distal Femoral Angle (mLDFA) is a crucial measurement in assessing frontal plane alignment of the femur. It is formed by the distal femoral joint orientation line and the femoral mechanical axis. According to the provided text, the normal range for the mLDFA is 85°-90°. An mLDFA less than 85° indicates a femoral valgus deformity, while an mLDFA greater than 90° indicates a femoral varus deformity. Options A, C, D, and E represent ranges outside the established normal values.

Question 2892

Topic: Lower Extremity Trauma

A 70-year-old patient with a significant knee flexion contracture (e.g., 30° procurvatum of the distal femur) requires an AP long-leg radiograph to assess frontal plane alignment. Standard AP views obtained with the beam perpendicular to the film show overlapped joint surfaces, making accurate measurements impossible.

To obtain a clear AP view of the knee joint surfaces for accurate measurement in this scenario, what modification to the radiographic technique is necessary?

. Increase the X-ray beam intensity to penetrate the overlapped bone
. Position the patient supine with the knee fully extended by force
. Angle the X-ray beam upward, tangential to the joint surfaces, by the amount of sagittal angulation
. Rotate the limb externally by 15 degrees to separate the condyles
. Obtain a lateral view radiograph instead, as AP views are unreliable in this situation

Correct Answer & Explanation

. Angle the X-ray beam upward, tangential to the joint surfaces, by the amount of sagittal angulation

Explanation

Correct Answer: CThe text addresses the challenge of obtaining clear radiographs when a deformity component exists in an orthogonal plane. Specifically, for a sagittal plane deformity affecting an AP view, it states: 'When there is a sagittal plane component of deformity, the AP view radiograph obtained in the usual fashion appears distorted (~Fig. 3-25a). To assess the joint orientation, the radiograph should be obtained inclined by the amount of sagittal plane angulation (~Fig. 3-25b and c).' This means angling the beam to be tangential to the joint surfaces, which in the case of procurvatum (flexion deformity) would involve aiming the beam upward from an anterior-proximal to a posterior-distal position. Options A, B, D, and E either do not address the issue of joint surface overlap, are impractical, or would not yield the desired frontal plane alignment information.

Question 2893

Topic: Lower Extremity Trauma

A 35-year-old male presents with a complex post-traumatic deformity of the right femur. During preoperative planning, the surgeon draws the anatomic and mechanical axes of the femur. Which of the following statements accurately describes the relationship between the femoral anatomic and mechanical axes in the frontal plane?

. The femoral anatomic axis and mechanical axis are collinear, similar to the tibia.
. The femoral anatomic axis passes through the center of the hip joint, while the mechanical axis exits at the greater trochanter.
. The femoral anatomic axis and mechanical axis diverge by approximately 7 degrees (± 2°) in the frontal plane.
. The femoral anatomic axis is used for intramedullary nailing, but it is always parallel to the mechanical axis.
. The femoral mechanical axis is defined by the mid-diaphyseal line, whereas the anatomic axis connects joint centers.

Correct Answer & Explanation

. The femoral anatomic axis and mechanical axis diverge by approximately 7 degrees (± 2°) in the frontal plane.

Explanation

Correct Answer: CThe case explicitly states, "in the frontal plane of the femur, the mechanical and anatomic axes diverge by approximately 7 degrees (± 2°). Therefore, the femoral PMA and PAA are distinctly different lines, as are the DMA and DAA. Recognizing this 7-degree divergence is critical when planning distal femoral osteotomies." This divergence is a fundamental concept in lower limb deformity correction.Option A is incorrectbecause, while the tibial anatomic and mechanical axes are nearly collinear, the femoral axes are not. Conflating the two is a common pitfall.Option B is incorrect. The anatomic axis of the femur exits proximally at the tip of the greater trochanter (or piriformis fossa), not through the center of the hip joint. The mechanical axis connects the center of the femoral head to the center of the knee joint.Option D is incorrect. While the anatomic axis is indeed used for intramedullary nailing, it is not always parallel to the mechanical axis in the femur; they diverge by approximately 7 degrees.Option E is incorrect. This statement reverses the definitions. The anatomic axis is defined by the mid-diaphyseal line, and the mechanical axis connects the center points of the joints.

Question 2894

Topic: 2. Trauma

A 28-year-old patient presents with a post-traumatic varus deformity of the mid-diaphyseal tibia. During preoperative planning, the surgeon identifies the intersection point of the proximal and distal mechanical axes of the tibia, as shown in the image. What is the clinical significance of this intersection point, and what is the primary consequence of ignoring it during osteotomy planning?

. It represents the ideal location for intramedullary nail insertion, and ignoring it leads to malunion.
. It is the Center of Rotation of Angulation (CORA), and ignoring it will result in iatrogenic translation and a 'dog-leg' deformity.
. It indicates the magnitude of the deformity, and ignoring it will cause nonunion.
. It is the point where the anatomic axis crosses the mechanical axis, and ignoring it leads to joint stiffness.
. It is the ideal location for external fixator pin placement, and ignoring it causes nerve damage.

Correct Answer & Explanation

. It is the Center of Rotation of Angulation (CORA), and ignoring it will result in iatrogenic translation and a 'dog-leg' deformity.

Explanation

Correct Answer: BThe case defines the Center of Rotation of Angulation (CORA) as "The exact point at which these proximal and distal axis lines intersect." It further states, "The CORA is the holy grail of deformity planning. It dictates precisely where the apex of the deformity lies and, consequently, where the optimal level of the osteotomy (the bone cut) or hinge placement for a dynamic external fixator should be located." The critical consequence of ignoring the CORA is also highlighted: "If a surgeon ignores the CORA and simply cuts the bone wherever it is surgically convenient, they risk violating Paley's Osteotomy Rules. Cutting away from the CORA and simply angulating the bone to correct the axis will introduceiatrogenic translation—a 'dog-leg' deformity where the bone ends no longer line up anatomically."Option A is incorrect. While the CORA is crucial for osteotomy, it is not directly the ideal location for intramedullary nail insertion, and malunion is a general complication, not the specific iatrogenic translation described.Option C is incorrect. The angle formed at the CORA indicates the magnitude, but the CORA itself is the location. Ignoring the CORA leads to translation, not primarily nonunion.Option D is incorrect. The CORA is the intersection of theproximal and distal axis lines(mechanical or anatomic, depending on planning), not where the anatomic and mechanical axes cross each other in a normal bone. Joint stiffness is not the primary consequence of ignoring the CORA.Option E is incorrect. While the CORA can guide hinge placement for external fixators, it's not specifically for pin placement, and nerve damage is not the direct consequence of ignoring the CORA in terms of alignment.

Question 2895

Topic: Lower Extremity Trauma

During correction of a tibial shaft deformity, the osteotomy and the hinge (axis of correction of angulation, ACA) are both placed distal to the true Center of Rotation of Angulation (CORA). What is the primary mechanical consequence of this technical error?

. Perfect realignment of the mechanical axis.
. Correction of the angular deformity with a new translational deformity (zigzag effect).
. Pure translation without any angular change.
. Spontaneous correction of rotational malalignment.
. Preservation of the anatomical axis with deviation of the joint lines.

Correct Answer & Explanation

. Correction of the angular deformity with a new translational deformity (zigzag effect).

Explanation

Osteotomy Rule 3 dictates that if both the osteotomy and the ACA are placed away from the CORA, the angular deformity may be corrected but a new unintended translational deformity will be created. This leads to a zigzag mechanical axis.

Question 2896

Topic: 2. Trauma

A surgeon is planning a proximal tibial osteotomy for a varus deformity. Compared to an opening wedge osteotomy, a closing wedge osteotomy at this location will most likely result in which of the following?

. An increase in absolute limb length.
. A decrease in absolute limb length.
. Increased risk of nonunion due to larger gap size.
. Increased tension on the common peroneal nerve.
. Greater preservation of the posterior tibial slope.

Correct Answer & Explanation

. A decrease in absolute limb length.

Explanation

A closing wedge osteotomy removes a wedge of bone, inherently leading to a decrease in the absolute length of the bone segment. In contrast, opening wedge osteotomies generally increase absolute limb length.

Question 2897

Topic: 2. Trauma

A patient has a distal femoral fracture that has healed with internal rotation malunion. How will this rotational deformity primarily affect the measurement of the Mechanical Lateral Distal Femoral Angle (mLDFA) on a standard anteroposterior (AP) radiograph?

. It will falsely increase the apparent varus of the distal femur.
. It will falsely increase the apparent valgus of the distal femur.
. It will accurately reflect the true deformity magnitude.
. It will cause the joint line convergence angle to become negative.
. It will eliminate the anatomic-mechanical axis angle difference.

Correct Answer & Explanation

. It will falsely increase the apparent varus of the distal femur.

Explanation

Rotation alters the projection of the normal femoral bow and condylar anatomy on a 2D radiograph. Internal rotation typically creates a spurious varus appearance, falsely increasing the mLDFA measurement.

Question 2898

Topic: Lower Extremity Trauma

In evaluating a lower extremity deformity, a standing full-length radiograph

reveals a mechanical axis deviation (MAD) of 30 mm medial to the knee center. The mechanical lateral distal femoral angle (mLDFA) is 87° and the medial proximal tibial angle (MPTA) is 78°. The joint line convergence angle (JLCA) is 2°. Which of the following is the primary location of the deformity?

. Proximal femur
. Distal femur
. Proximal tibia
. Distal tibia
. Intra-articular knee ligamentous laxity

Correct Answer & Explanation

. Proximal tibia

Explanation

The MPTA is abnormally low (normal is 87°), indicating a structural proximal tibial varus deformity. The mLDFA and JLCA are within normal limits, ruling out femoral and intra-articular causes.

Question 2899

Topic: 2. Trauma

A 25-year-old male has a malunited tibial fracture with an apex anterolateral deformity. To achieve full correction of both the angulation and translation simultaneously using a single cut, the osteotomy and the hinge (axis of correction) must be placed at which of the following locations?

. Osteotomy at the CORA, hinge at the CORA.
. Osteotomy proximal to the CORA, hinge distal to the CORA.
. Osteotomy distal to the CORA, hinge at the CORA.
. Osteotomy distal to the CORA, hinge distal to the CORA.
. Osteotomy at the CORA, hinge proximal to the CORA.

Correct Answer & Explanation

. Osteotomy at the CORA, hinge at the CORA.

Explanation

According to Osteotomy Rule 1, placing both the osteotomy and the axis of correction (hinge) exactly at the CORA will completely correct the angulation and realign the axis without introducing any translation.

Question 2900

Topic: Lower Extremity Trauma

An 18-year-old male with a shortened limb and a valgus deformity requires correction. A dome osteotomy is planned at the distal femur. What is the primary geometric advantage of a dome osteotomy in this scenario?

. It inherently lengthens the limb by 2 cm without distraction.
. It allows correction of angulation without altering length or causing translation when the hinge is at the center.
. It avoids the need for internal fixation.
. It permits correction of rotational deformities more easily than a transverse cut.
. It drastically alters the mechanical lateral proximal femoral angle.

Correct Answer & Explanation

. It allows correction of angulation without altering length or causing translation when the hinge is at the center.

Explanation

A dome osteotomy permits pure angular correction by rotating the bone segments along the arc of the cut. When the CORA is at the center of the dome, no gap is created, length is preserved, and translation is avoided.

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