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2. Trauma MCQs

Practice Set 482 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 9621

Topic: Upper Extremity Trauma

What is the most common approach to assess the integrity of the interosseous membrane (IOM) when an Essex-Lopresti lesion is suspected?

. Direct visualization during open surgery
. Standard wrist radiographs
. MRI of the forearm
. Ultrasound of the forearm
. CT scan of the elbow

Correct Answer & Explanation

. MRI of the forearm

Explanation

MRI of the forearm is the most effective imaging modality for directly assessing the integrity of the interosseous membrane (IOM). It can visualize tears, avulsions, or other disruptions of the IOM that are critical for diagnosing an Essex-Lopresti lesion. Standard radiographs might show proximal radial migration (indirect sign), but MRI provides direct visualization of the soft tissue injury. CT is good for bone, ultrasound is less reliable for deep IOM structures.

Question 9622

Topic: 2. Trauma
When is radial head replacement generally favored over open reduction internal fixation (ORIF) for radial head fractures?
. For Mason-Johnston Type I fractures
. For non-displaced fractures with a small articular step-off
. When the fracture is highly comminuted, non-reconstructible, or associated with significant elbow instability (e.g., terrible triad, Essex-Lopresti)
. In pediatric patients with open growth plates
. For all Mason-Johnston Type II fractures

Correct Answer & Explanation

. When the fracture is highly comminuted, non-reconstructible, or associated with significant elbow instability (e.g., terrible triad, Essex-Lopresti)

Explanation

Radial head replacement is generally favored over ORIF for radial head fractures that are highly comminuted and not amenable to stable reconstruction (typically Mason-Johnston Type III or IV), or when there are associated severe instabilities like a terrible triad injury or an Essex-Lopresti lesion.

Question 9623

Topic: 2. Trauma
What specific type of fracture is typically managed with non-operative treatment consisting of brief immobilization and early range of motion?
. Mason-Johnston Type III
. Radial head fracture with >2mm step-off
. Fracture with a palpable block to forearm rotation
. Mason-Johnston Type I
. Radial neck fracture with >45 degrees angulation

Correct Answer & Explanation

. Mason-Johnston Type I

Explanation

Mason-Johnston Type I radial head fractures are non-displaced or minimally displaced and typically have no mechanical block to motion. These are managed non-operatively with a brief period of immobilization for comfort, followed by early active range of motion to prevent stiffness.

Question 9624

Topic: 2. Trauma

When assessing the healing of a radial head fracture treated with ORIF, what is the primary radiographic sign to look for before escalating rehabilitation?

. Complete resolution of swelling
. Absence of pain
. Evidence of bridging callus formation across the fracture site
. Full return of muscle strength
. Perfect restoration of anatomical alignment

Correct Answer & Explanation

. Evidence of bridging callus formation across the fracture site

Explanation

Evidence of bridging callus formation across the fracture site on radiographs is the primary sign of biological healing. This indicates that the fracture is gaining stability and can tolerate increased stress, allowing for escalation of rehabilitation exercises and activity levels. While resolution of swelling and pain are good clinical signs, osseous healing is the key biological indicator. Perfect anatomical alignment is a goal of surgery, not necessarily a sign of healing itself. Full strength comes much later in rehab.

Question 9625

Topic: 2. Trauma

What is the primary concern when managing a radial head fracture in an elderly, osteoporotic patient?

. High risk of non-union
. Difficulty achieving stable fixation with standard implants
. Increased likelihood of nerve injury
. Exacerbation of pre-existing arthritis
. Rapid progression to infection

Correct Answer & Explanation

. Difficulty achieving stable fixation with standard implants

Explanation

In elderly, osteoporotic patients, the primary concern when managing a radial head fracture with ORIF is the difficulty in achieving stable fixation with standard implants due to poor bone quality. Osteoporotic bone often cannot hold screws and plates securely, leading to construct failure, particularly in comminuted fractures. This might necessitate a change in strategy towards radial head replacement or even excision, depending on the patient's demand and the fracture pattern. While non-union and arthritis are concerns, fixation stability is paramount.

Question 9626

Topic: 2. Trauma

Which of the following statements about radial head prostheses is true?

. All radial head prostheses are made of silicone.
. They are primarily used for Type I fractures.
. Modular metallic implants allow for restoration of radial length and prevent proximal migration.
. They commonly lead to early loosening due to aggressive bone ingrowth.
. Long-term results are consistently superior to ORIF for all fracture types.

Correct Answer & Explanation

. Modular metallic implants allow for restoration of radial length and prevent proximal migration.

Explanation

Modular metallic radial head prostheses are crucial for restoring radial length and providing stability, particularly in complex, unreconstructible fractures or those associated with forearm instability (Essex-Lopresti). They prevent proximal migration of the radius and maintain proper forearm mechanics. Silicone implants have fallen out of favor due to wear and osteolysis. Prostheses are not used for Type I fractures. While long-term results can be excellent for appropriate indications, they are not superior to ORIF forallfracture types, especially reconstructible ones. Loosening can occur but is not typically due to aggressive bone ingrowth.

Question 9627

Topic: 2. Trauma

Which of the following imaging modalities is considered the gold standard for detailed assessment of ligamentous injuries of the elbow, frequently associated with radial head fractures?

. Plain radiographs
. CT scan
. MRI scan
. Ultrasound
. Bone scan

Correct Answer & Explanation

. MRI scan

Explanation

MRI (Magnetic Resonance Imaging) is considered the gold standard for detailed assessment of soft tissue structures, including ligaments (e.g., medial collateral ligament, lateral ulnar collateral ligament, annular ligament), tendons, and the interosseous membrane around the elbow. While radiographs and CT are excellent for bony injuries, MRI provides superior visualization of ligamentous tears and capsular disruptions often associated with complex radial head fractures and dislocations.

Question 9628

Topic: 2. Trauma
A 7-year-old child presents with elbow pain and swelling after falling from a tree. Radiographs show a fracture of the ulnar metaphysis and a lateral dislocation of the radial head. Which Bado and Peril type is this?
. Type I
. Type II
. Type III
. Type IV
. Essex-Lopresti

Correct Answer & Explanation

. Type III

Explanation

This presentation describes a Bado and Peril Type III Monteggia fracture. Type III is characterized by a fracture of the ulnar metaphysis (often proximally, near the olecranon or coronoid) with an associated lateral or anterolateral dislocation of the radial head. This type is more common in children due to the inherent elasticity of pediatric bones and ligaments. Type I is anterior radial head dislocation with an anteriorly angulated ulnar shaft fracture; Type II is posterior radial head dislocation with a posteriorly angulated ulnar shaft fracture; Type IV is anterior radial head dislocation with fractures of both the ulna and radius shafts. Essex-Lopresti is a radial head fracture with interosseous membrane disruption and DRUJ dissociation.

Question 9629

Topic: 2. Trauma
What is the most common reason for failure of closed reduction of a Monteggia fracture in a child?
. Excessive edema
. Interposition of soft tissues (e.g., annular ligament, joint capsule)
. Unrecognized physeal injury
. Poor patient compliance with immobilization
. Insufficient anesthesia

Correct Answer & Explanation

. Interposition of soft tissues (e.g., annular ligament, joint capsule)

Explanation

In children, the most common reason for failure of closed reduction of a Monteggia fracture (especially Type III and I) is the interposition of soft tissues within the radiocapitellar joint, preventing concentric reduction of the radial head. The annular ligament is the most common tissue to become trapped (buttonholing), but fragments of the joint capsule or even the biceps tendon can also impede reduction. While edema, physeal injury, or compliance issues can contribute to management difficulties, the mechanical block from soft tissue interposition is a direct cause of irreducible radial head dislocation requiring open reduction. Sufficient anesthesia is a prerequisite for any reduction attempt.

Question 9630

Topic: 2. Trauma

Which nerve is most commonly injured in Monteggia fractures, particularly Type I?

. Ulnar nerve
. Median nerve
. Radial nerve
. Posterior interosseous nerve (PIN)
. Anterior interosseous nerve (AIN)

Correct Answer & Explanation

. Posterior interosseous nerve (PIN)

Explanation

The posterior interosseous nerve (PIN), a branch of the radial nerve, is the most commonly injured nerve in Monteggia fractures. It is particularly vulnerable in Type I fractures due to the anterior displacement of the radial head and hyperpronation mechanism, causing significant stretching as the nerve passes through the supinator muscle (arcade of Frohse). PIN palsy manifests as weakness or inability to extend the fingers at the MCP joints and weakness of thumb extension. Most PIN palsies associated with Monteggia injuries are neurapraxic and recover spontaneously, but careful monitoring is essential.

Question 9631

Topic: 2. Trauma
Which of the following describes a Bado Type II Monteggia fracture?
. Anterior dislocation of the radial head with an anteriorly angulated ulnar shaft fracture
. Posterior dislocation of the radial head with a posteriorly angulated ulnar shaft fracture
. Lateral dislocation of the radial head with a ulnar metaphyseal fracture
. Anterior dislocation of the radial head with fractures of both the ulna and radius shafts
. Distal radial shaft fracture with DRUJ disruption

Correct Answer & Explanation

. Posterior dislocation of the radial head with a posteriorly angulated ulnar shaft fracture

Explanation

A Bado Type II Monteggia fracture is characterized by a posterior dislocation of the radial head, typically associated with a posteriorly angulated ulnar shaft fracture. This type accounts for about 15% of Monteggia fractures and is often seen in adults from a direct blow or fall with the elbow in flexion. Type I is anterior dislocation with anterior ulnar angulation; Type III is lateral dislocation with metaphyseal ulnar fracture; Type IV is anterior radial head dislocation with both radial and ulnar shaft fractures. Distal radial shaft fracture with DRUJ disruption is a Galeazzi fracture.

Question 9632

Topic: 2. Trauma

A 60-year-old active female undergoes ORIF of a Monteggia Type I fracture. Six weeks post-operatively, she complains of increasing elbow stiffness. Radiographs show heterotopic ossification (HO) around the elbow joint. What is the most appropriate initial management for this complication?

. Immediate surgical excision of the heterotopic ossification
. High-dose radiation therapy to the elbow
. Continued physiotherapy, NSAIDs, and potentially low-dose radiation or bisphosphonates if progressive
. Application of continuous passive motion (CPM) immediately post-op
. Elbow fusion to prevent further ossification

Correct Answer & Explanation

. Continued physiotherapy, NSAIDs, and potentially low-dose radiation or bisphosphonates if progressive

Explanation

Heterotopic ossification (HO) is a recognized complication after elbow trauma, including Monteggia fractures and their surgical treatment. Initial management for developing HO usually involves a combination of non-steroidal anti-inflammatory drugs (NSAIDs) like indomethacin (if not contraindicated) and continued, gentle physiotherapy to maintain range of motion. For severe or rapidly progressive HO, low-dose radiation therapy or bisphosphonates might be considered. Surgical excision of HO is generally delayed until the HO is mature (typically 6-12 months post-injury, when it has become quiescent) and only if it significantly limits function. CPM can be helpful in the acute post-op phase to prevent stiffness but isn't a primary treatment for established HO. Elbow fusion is a salvage procedure, not indicated for HO.

Question 9633

Topic: 2. Trauma

Which factor is most associated with an increased risk of posterior interosseous nerve (PIN) injury in Monteggia fractures?

. Open fracture
. High-energy trauma
. Type I Monteggia fracture (anterior radial head dislocation)
. Patient age over 60 years
. Associated olecranon fracture

Correct Answer & Explanation

. Type I Monteggia fracture (anterior radial head dislocation)

Explanation

The posterior interosseous nerve (PIN) is most commonly injured in Bado Type I Monteggia fractures, which involve anterior dislocation of the radial head. This specific nerve is vulnerable to stretching and compression as it passes through the supinator muscle (Arcade of Frohse) during the hyperpronation and anterior displacement mechanism characteristic of Type I injuries. While high-energy trauma can increase overall injury severity, and open fractures carry risks of direct nerve laceration, the specific anatomical vulnerability of the PIN is highest in Type I Monteggia. Age or olecranon fracture are not primary risk factors for PIN injury in Monteggia.

Question 9634

Topic: 2. Trauma

What is the expected outcome if a Monteggia fracture in an adult is treated by closed reduction and casting alone, especially for Type I?

. High success rate with good functional outcomes, similar to pediatric cases
. High risk of redislocation of the radial head and ulnar malunion, leading to poor function
. Development of early onset osteoarthritis in the elbow joint but good forearm rotation
. Excellent bone healing but persistent nerve palsy
. Spontaneous remodeling of the ulna fracture, even if malreduced

Correct Answer & Explanation

. High risk of redislocation of the radial head and ulnar malunion, leading to poor function

Explanation

Unlike in children, closed reduction and casting alone for adult Monteggia fractures (especially Type I) almost always lead to an unsatisfactory outcome. The adult periosteum is less robust, and the injury forces are usually higher, making stable reduction very difficult to achieve and maintain with casting alone. This typically results in redislocation of the radial head and/or malunion or nonunion of the ulna, leading to chronic pain, severe loss of forearm rotation, instability, and early degenerative changes. Therefore, surgical fixation of the ulna is the standard of care for adults.

Question 9635

Topic: 2. Trauma
Which Bado and Peril type is characterized by an anterior dislocation of the radial head with fractures of both the ulna and radius shafts?
. Type I
. Type II
. Type III
. Type IV
. Galeazzi

Correct Answer & Explanation

. Type IV

Explanation

This is the definition of a Bado Type IV Monteggia fracture. It is the least common type. Type I involves anterior dislocation of radial head with anterior angulation of ulnar fracture. Type II involves posterior dislocation of radial head with posterior angulation of ulnar fracture. Type III involves lateral/anterolateral dislocation of radial head with ulnar metaphyseal fracture. Galeazzi involves a distal radial shaft fracture with DRUJ disruption, not a Monteggia.

Question 9636

Topic: 2. Trauma

When planning surgery for an adult Monteggia Type I fracture, what type of implant is typically used for fixation of the ulnar fracture?

. Intramedullary nail
. External fixator
. K-wires
. Lag screws only
. Dynamic compression plate (DCP) or locking compression plate (LCP)

Correct Answer & Explanation

. Dynamic compression plate (DCP) or locking compression plate (LCP)

Explanation

For adult ulnar shaft fractures associated with Monteggia injuries, open reduction and internal fixation with a plate and screws is the standard of care. A dynamic compression plate (DCP) or a locking compression plate (LCP) are commonly used. These plates provide stable fixation, allowing for anatomical reduction of the ulna, which is paramount for radial head stability. Intramedullary nails are less commonly used for diaphyseal ulnar fractures in this context, K-wires offer insufficient stability in adults, external fixation is reserved for specific open/contaminated injuries, and lag screws alone would not provide sufficient length and rotational stability.

Question 9637

Topic: 2. Trauma

What is the primary concern regarding neurovascular status to monitor in a patient with a Monteggia fracture, particularly Type I?

. Ulnar artery patency
. Median nerve sensory function in the thumb, index, and middle fingers
. Radial nerve motor function (wrist drop)
. Posterior interosseous nerve (PIN) motor function (finger and thumb extension)
. Brachial artery integrity

Correct Answer & Explanation

. Posterior interosseous nerve (PIN) motor function (finger and thumb extension)

Explanation

The posterior interosseous nerve (PIN), a motor branch of the radial nerve, is the most commonly affected nerve in Monteggia fractures, especially Type I. Therefore, careful assessment of PIN function, specifically the ability to extend the fingers at the MCP joints and the thumb, is critical. While overall neurovascular status must be assessed, PIN injury is characteristic of Monteggia. Median and ulnar nerve injuries are less common, and brachial artery injury is rare unless there is severe displacement or associated vascular compromise.

Question 9638

Topic: 2. Trauma

A Monteggia fracture in a 3-year-old is reduced, and the radial head appears stable. The ulnar fracture is plastic deformation only. What is the appropriate immobilization period?

. 1-2 weeks
. 3-4 weeks
. 6-8 weeks
. 10-12 weeks
. No immobilization, just a sling

Correct Answer & Explanation

. 6-8 weeks

Explanation

Even for pediatric Monteggia fractures with plastic deformation of the ulna (where the ulna is not fully fractured but bent), achieving and maintaining radial head reduction is paramount. The healing time for the plastically deformed ulna to remodel and become stable, and for the stretched/torn annular ligament to heal sufficiently to stabilize the radial head, typically requires a minimum of 6 weeks of immobilization in a long-arm cast. Shorter periods risk redislocation. While children's bones heal faster, the stability of the radiocapitellar joint and ulnar remodeling demands adequate time. Longer periods might be needed for frank ulnar fractures.

Question 9639

Topic: 2. Trauma
Which of the following describes the Bado and Peril classification type most commonly missed by emergency room physicians?
. Type I
. Type II
. Type III
. Type IV
. All types are equally likely to be missed.

Correct Answer & Explanation

. Type III

Explanation

Bado Type III Monteggia fractures are often cited as the most commonly missed type, particularly in children. This is because the ulnar fracture is often a metaphyseal fracture (sometimes just a greenstick or plastic deformation) rather than a clear diaphyseal fracture, and the radial head dislocation can be subtle (lateral or anterolateral) and may not be immediately obvious if elbow views are suboptimal or incomplete. A 'bent bone' with a dislocated radial head can be easily overlooked. Missed Type I injuries are also frequent, but Type III has a specific notoriety for being insidious in presentation.

Question 9640

Topic: 2. Trauma

What is a major differentiating factor between a Monteggia fracture and a Galeazzi fracture?

. The presence of a nerve injury.
. The age of the patient (children vs. adults).
. The presence of an open wound.
. The location of the primary bone fracture (proximal ulna vs. distal radius) and the associated joint injury.
. The need for surgical intervention.

Correct Answer & Explanation

. The location of the primary bone fracture (proximal ulna vs. distal radius) and the associated joint injury.

Explanation

The key differentiating factor between a Monteggia and Galeazzi fracture lies in the location of the primary bony injury and the associated joint disruption. A Monteggia fracture involves a fracture of the ulna (typically proximal or mid-shaft) with an associated dislocation of the radial head at the elbow. A Galeazzi fracture involves a fracture of the distal radius with an associated disruption (dislocation or subluxation) of the distal radioulnar joint (DRUJ). Both typically require surgical intervention in adults and can occur at any age, and both can be open or associated with nerve injury, but the anatomical location is distinct.

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