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2. Trauma MCQs

Practice Set 485 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 9681

Topic: 2. Trauma

Plate and screw fixation for comminuted olecranon fractures primarily provides stability through what mechanism?

. Converting tensile forces to compressive forces
. Intramedullary fixation
. Neutralization, buttress, and/or bridging principles
. Distraction osteogenesis
. External compression

Correct Answer & Explanation

. Neutralization, buttress, and/or bridging principles

Explanation

Plate and screw fixation for comminuted fractures primarily acts as a neutralization, buttress, or bridging construct (C). Neutralization plates protect screws from bending, shear, and rotational forces. Buttress plates prevent fragment collapse. Bridging plates span comminuted segments, maintaining length and alignment. Tension band wiring (A) is for simple fractures. Intramedullary fixation (B) is a different method. Distraction osteogenesis (D) is for lengthening. External compression (E) is typically from external fixators or specific compression plate designs used for simple fractures.

Question 9682

Topic: 2. Trauma

In pre-operative planning for a complex olecranon fracture, what imaging modality offers the most detailed assessment of articular congruity and fragment orientation, particularly for surgical reduction and fixation strategy?

. Plain radiographs (AP/Lateral)
. MRI with contrast
. CT scan with 3D reconstruction
. Ultrasound
. Bone scan

Correct Answer & Explanation

. CT scan with 3D reconstruction

Explanation

A CT scan with 3D reconstruction (C) provides the most detailed information regarding the extent of comminution, articular step-off, fragment size and orientation, and overall joint congruity. This is invaluable for surgical planning, especially for complex or intra-articular fractures. Plain radiographs (A) are initial. MRI (B) is better for soft tissues. Ultrasound (D) and bone scan (E) are less useful for bony detail in acute fracture assessment.

Question 9683

Topic: 2. Trauma

Which of the following fracture patterns is a relative contraindication to tension band wiring?

. Simple transverse fracture
. Short oblique fracture with stable ulnohumeral joint
. Highly comminuted olecranon fracture with poor bone stock
. Transverse fracture with intact triceps mechanism
. Distal olecranon avulsion fracture

Correct Answer & Explanation

. Highly comminuted olecranon fracture with poor bone stock

Explanation

Highly comminuted olecranon fractures with poor bone stock (C) are a relative contraindication to tension band wiring. Tension band wiring relies on good bone purchase for the Kirschner wires and adequate compression. In highly comminuted fractures, especially with osteoporotic bone, stable fixation and compression may be difficult to achieve, leading to higher rates of failure and nonunion. Plate fixation is often preferred in such cases. The other options are generally well-suited for TBW if displaced.

Question 9684

Topic: 2. Trauma

The most significant factor contributing to the development of post-traumatic arthritis following an olecranon fracture is:

. Age of the patient
. Duration of immobilization
. Non-anatomic articular reduction with residual step-off or gap
. Early hardware removal
. Mild superficial infection

Correct Answer & Explanation

. Non-anatomic articular reduction with residual step-off or gap

Explanation

Non-anatomic articular reduction with residual step-off or gap (C) is the most significant factor leading to post-traumatic arthritis. Any irregularity in the joint surface increases contact stress, disrupts normal biomechanics, and accelerates cartilage degeneration. While other factors contribute, articular incongruity is directly detrimental to long-term joint health.

Question 9685

Topic: 2. Trauma

A patient with an olecranon fracture is unable to actively extend their elbow against gravity. This finding suggests disruption of which functional unit?

. Biceps-brachialis complex
. Forearm supinator-pronator group
. Triceps-olecranon lever arm mechanism
. Wrist extensor compartment
. Anconeus-brachioradialis synergy

Correct Answer & Explanation

. Triceps-olecranon lever arm mechanism

Explanation

The inability to actively extend the elbow against gravity is a hallmark sign of disruption to the triceps-olecranon lever arm mechanism (C). The triceps muscle inserts onto the olecranon, and an intact fracture with stable fixation (or an intact olecranon) is required for effective elbow extension. If this mechanism is disrupted (e.g., by a displaced olecranon fracture or triceps avulsion), active extension is severely compromised.

Question 9686

Topic: 2. Trauma

When evaluating a patient with a suspected olecranon fracture in the emergency department, what is the single most important initial assessment to perform and document?

. Detailed fracture classification
. Elbow range of motion
. Distal neurovascular status
. Pain level assessment
. Patient's tetanus immunization history

Correct Answer & Explanation

. Distal neurovascular status

Explanation

In any acute trauma, especially involving the elbow (where major neurovascular structures are superficial and can be compromised by fracture fragments or swelling), a thorough assessment and documentation of distal neurovascular status (C) is the single most important initial step. This can identify limb-threatening conditions (e.g., compartment syndrome, vascular injury) or nerve palsies that require immediate attention. Fracture classification (A) is for later. Range of motion (B) and pain assessment (D) are important but secondary to neurovascular status. Tetanus history (E) is relevant for open fractures.

Question 9687

Topic: 2. Trauma

How is a Mayo Type IA olecranon fracture typically managed?

. Urgent open reduction internal fixation with plate
. Tension band wiring
. Excision of olecranon fragment
. Non-operative management with long arm cast/splint
. Total elbow arthroplasty

Correct Answer & Explanation

. Non-operative management with long arm cast/splint

Explanation

A Mayo Type IA fracture is a non-displaced, non-comminuted, and stable fracture. These are typically managed non-operatively (D) with a long arm cast or splint (often in about 45-90 degrees of flexion to relax the triceps), allowing for early controlled range of motion as pain permits, to prevent stiffness. Surgical options (A, B, C, E) are overkill for a stable, non-displaced fracture.

Question 9688

Topic: 2. Trauma

When performing tension band wiring, what is the critical orientation for the two Kirschner wires to ensure proper biomechanical function and prevent fracture gapping?

. Parallel to the ulna shaft
. Perpendicular to the fracture line
. Divergent proximally and convergent distally, engaging the anterior cortex
. Convergent proximally and divergent distally, engaging the anterior cortex
. Placed only in the proximal fragment

Correct Answer & Explanation

. Divergent proximally and convergent distally, engaging the anterior cortex

Explanation

For proper tension band wiring, the two Kirschner wires should be inserted parallel to each other in the proximal fragment, divergent proximally and then advanced distally to engage the anterior cortex of the ulna (C). This provides a stable construct and prevents rotation or pull-out of the proximal fragment. Placing them parallel (A) throughout or perpendicular (B) would be biomechanically unsound. Divergent proximally and convergent distally (D) would not achieve optimal stability. Engaging only the proximal fragment (E) would not provide adequate fixation.

Question 9689

Topic: 2. Trauma

An elderly, low-demand patient presents with a severely comminuted fracture involving only the distal 15% of the olecranon, with triceps insertion still largely intact to the main ulna. What might be a reasonable consideration, especially if reconstruction is deemed too complex for the patient's functional needs?

. Tension band wiring
. Plate fixation
. Excision of the small distal fragment and triceps advancement
. Intramedullary screw
. Immobilization only

Correct Answer & Explanation

. Excision of the small distal fragment and triceps advancement

Explanation

For very small, severely comminuted distal olecranon fragments (<20% of the olecranon, typically <2cm) in elderly, low-demand patients where anatomical reconstruction is challenging or unnecessary, excision of the fragment and reattaching or advancing the triceps tendon to the remaining ulna (C) can provide satisfactory function. This avoids hardware-related complications and prolonged surgery, while restoring the extensor mechanism. Tension band wiring (A) and plate fixation (B) are difficult with small, comminuted fragments. Intramedullary screw (D) is not suitable. Immobilization only (E) would likely lead to nonunion and loss of extension.

Question 9690

Topic: 2. Trauma

In the context of olecranon fractures, a fracture is generally considered 'displaced' if there is greater than how many millimeters of separation or articular step-off?

. 0.5 mm
. 1 mm
. 2 mm
. 5 mm
. 10 mm

Correct Answer & Explanation

. 2 mm

Explanation

A fracture is generally considered displaced if there is greater than 2 mm (C) of separation or articular step-off. This threshold is commonly used to differentiate between fractures that can be managed non-operatively (if less than 2mm and stable) and those typically requiring operative intervention to restore anatomical alignment and function.

Question 9691

Topic: Upper Extremity Trauma

The anconeus muscle plays a role in elbow function and stability. Where does it primarily originate and insert relative to the olecranon?

. Origin: medial epicondyle; Insertion: olecranon fossa
. Origin: lateral epicondyle; Insertion: lateral aspect of olecranon and proximal ulna
. Origin: coracoid process; Insertion: olecranon
. Origin: radial head; Insertion: coronoid process
. Origin: medial supracondylar ridge; Insertion: medial aspect of olecranon

Correct Answer & Explanation

. Origin: lateral epicondyle; Insertion: lateral aspect of olecranon and proximal ulna

Explanation

The anconeus muscle originates from the posterior surface of the lateral epicondyle of the humerus and inserts onto the lateral aspect of the olecranon and the proximal ulna (B). It assists in elbow extension and stabilizes the ulnohumeral joint, particularly during pronation and supination.

Question 9692

Topic: 2. Trauma

A patient develops ulnar nerve symptoms (paresthesias in the small and ring fingers, intrinsic muscle weakness) 3 weeks after uneventful olecranon fracture fixation. What is the most likely cause?

. Acute nerve laceration during surgery
. Impingement by hardware
. Compartment syndrome of the forearm
. Ischemic injury secondary to vascular compromise
. Traumatic neuroma formation

Correct Answer & Explanation

. Impingement by hardware

Explanation

Delayed onset of ulnar nerve symptoms (B) weeks to months after fixation strongly suggests nerve irritation or impingement by the hardware (screws, k-wires, plate edge) or surrounding scar tissue/edema. Acute laceration (A) would present immediately post-operatively. Compartment syndrome (C) and ischemic injury (D) would present much earlier and more acutely, often with severe pain and motor deficits. Traumatic neuroma (E) would be a much later complication, typically months to years after nerve injury.

Question 9693

Topic: 2. Trauma
For an unstable olecranon fracture (Mayo Type III), what is the primary goal of surgical fixation?
. Preserve elbow extension only
. Prevent post-traumatic arthritis at all costs
. Restore ulnohumeral joint stability and congruity
. Avoid hardware removal
. Shorten the ulna to improve range of motion

Correct Answer & Explanation

. Restore ulnohumeral joint stability and congruity

Explanation

For unstable olecranon fractures (Mayo Type III, indicating associated elbow instability), the primary goal of surgical fixation is to restore ulnohumeral joint stability and congruity. Without a stable and congruent joint, proper function, early motion, and prevention of long-term complications like severe stiffness and arthritis are impossible. While preventing post-traumatic arthritis is a long-term goal, restoring stability is the immediate, overriding surgical objective.

Question 9694

Topic: 2. Trauma

In pediatric olecranon fractures, what specific consideration is important due to the presence of growth plates?

. Tension band wiring is always contraindicated.
. Non-displaced fractures always require surgery.
. Preserve the olecranon physis to prevent growth arrest or deformity.
. Ulnar nerve injury is impossible due to immature bone.
. Only plate fixation is recommended for all displaced fractures.

Correct Answer & Explanation

. Preserve the olecranon physis to prevent growth arrest or deformity.

Explanation

In pediatric olecranon fractures, it is crucial to preserve the olecranon physis (growth plate) (C) to prevent growth arrest, angular deformity, or length discrepancies. Surgical techniques, if required, must be carefully chosen to avoid damaging the physis. Tension band wiring (A) can be used in children, but K-wires must be placed carefully to avoid the physis. Non-displaced fractures (B) are often treated non-operatively. Ulnar nerve injury (D) is still a risk, as the nerve is present. Plate fixation (E) is an option but not the only one, and attention to the physis remains key.

Question 9695

Topic: 2. Trauma

Why is it crucial for the Kirschner wires in tension band wiring to engage the anterior cortex of the ulna?

. To protect the ulnar nerve from injury.
. To increase the length of the lever arm for the triceps.
. To prevent migration of the K-wires and provide stable anchorage.
. To allow for early weight-bearing on the elbow.
. To promote osteoinduction at the fracture site.

Correct Answer & Explanation

. To prevent migration of the K-wires and provide stable anchorage.

Explanation

Engaging the anterior cortex of the ulna (C) provides a strong bicortical purchase for the Kirschner wires, preventing them from backing out (pistoning) or migrating proximally. This ensures a stable construct that can effectively convert tensile forces into compression at the fracture site. Without anterior cortical engagement, the wires may be unstable, leading to fixation failure and loss of reduction.

Question 9696

Topic: 2. Trauma

A patient presents after a fall with a suspected olecranon fracture and complete inability to actively extend the elbow. Other than an olecranon fracture, what condition should be included in the differential diagnosis for this specific functional deficit?

. Radial head fracture
. Distal biceps tendon rupture
. Medial epicondyle avulsion
. Triceps tendon rupture
. Interosseous membrane rupture

Correct Answer & Explanation

. Triceps tendon rupture

Explanation

A complete inability to actively extend the elbow strongly suggests a disruption of the extensor mechanism. While an olecranon fracture is primary, a triceps tendon rupture (D) (either from its insertion on the olecranon or more proximally) would produce the same inability to actively extend the elbow. Radial head fracture (A) affects rotation and flexion/extension with pain. Biceps rupture (B) affects flexion and supination. Medial epicondyle avulsion (C) affects valgus stability and flexion (common flexor origin). Interosseous membrane rupture (E) affects forearm stability.

Question 9697

Topic: 2. Trauma

Intramedullary (IM) screw fixation for olecranon fractures is occasionally considered. In which specific scenario might it be a suitable choice?

. Highly comminuted intra-articular fractures.
. Simple transverse fractures without comminution, particularly in osteoporotic bone.
. Open fractures with significant contamination.
. Avulsion of the triceps insertion only, without bone fragment.
. Fractures with associated ulnar shaft involvement (Monteggia equivalent).

Correct Answer & Explanation

. Simple transverse fractures without comminution, particularly in osteoporotic bone.

Explanation

Intramedullary screw fixation (B) can be a suitable option for simple transverse or short oblique fractures without comminution, particularly in osteoporotic bone where Kirschner wires might not hold well, or in situations where hardware prominence from TBW is a major concern. It can act as a load-sharing device. It is generally not ideal for comminuted fractures (A) as it doesn't provide articular compression. For avulsion of the triceps (D), suture anchors are typically used. Open fractures (C) require different considerations. Ulnar shaft involvement (E) typically requires plate fixation of the shaft.

Question 9698

Topic: 2. Trauma

A 28-year-old active male presents with a Mayo Type IIA olecranon fracture. Which of the following is the most appropriate initial treatment plan?

. Non-operative management with sling only
. Long arm cast immobilization for 6 weeks
. Tension band wiring
. Plate and screw fixation
. Total elbow arthroplasty

Correct Answer & Explanation

. Tension band wiring

Explanation

Mayo Type IIA is a displaced, noncomminuted, and stable fracture. For active patients, operative fixation is indicated to restore the triceps mechanism and allow for early motion and optimal function. Tension band wiring (C) is the gold standard for this fracture pattern due to its ability to convert tensile forces to compression and provide stable fixation for early rehabilitation. Sling only (A) or prolonged cast (B) would lead to stiffness and potential nonunion in a displaced fracture. Plate fixation (D) is generally considered overkill for a simple fracture but might be an alternative. TEA (E) is a salvage procedure.

Question 9699

Topic: 2. Trauma

If hardware removal is indicated following tension band wiring for an olecranon fracture, what is the earliest time point it is typically considered, assuming fracture union?

. 1-2 weeks post-op
. 6-8 weeks post-op
. 3-4 months post-op
. 6-12 months post-op
. Never, hardware should remain permanently

Correct Answer & Explanation

. 6-12 months post-op

Explanation

Hardware removal (D) for olecranon tension band wiring is typically considered 6-12 months post-operatively, after solid radiographic union has been achieved and often in response to hardware-related symptoms (e.g., prominence, irritation). Removing it earlier (A, B, C) risks refracture through the healing bone. While hardware can remain permanently if asymptomatic (E), it's very common to remove it due to its superficial location.

Question 9700

Topic: 2. Trauma

During which part of a posterior surgical approach for an olecranon fracture is the ulnar nerve at the highest risk of iatrogenic injury?

. Incision of skin and subcutaneous tissue
. Dissection of the triceps fascia and muscle
. Retraction of soft tissues medially during exposure of the fracture
. Drilling K-wires or screws from lateral to medial
. Closure of the wound

Correct Answer & Explanation

. Retraction of soft tissues medially during exposure of the fracture

Explanation

The ulnar nerve is at highest risk during medial soft tissue retraction (C) to expose the olecranon and during instrumentation (e.g., drilling K-wires or screws, particularly if directed medially). Aggressive or careless retraction of the soft tissues to expose the medial column or the entire olecranon can stretch or compress the nerve, especially if it's not formally identified and protected or transposed. While drilling can injure, retraction is a constant risk during the exposure phase. The nerve is usually protected after initial identification, but sustained or forceful retraction is often the culprit.

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