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Elbow & Forearm MCQs

Practice Set 42 of 57

This practice set contains high-yield board review questions covering key concepts in Elbow & Forearm. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 821

Topic: Elbow & Forearm

Which type of implant is generally preferred for radial head replacement in an acute fracture setting?

. Monoblock polyethylene implants
. Bipolar metallic implants
. Modular metallic implants
. Silicone implants
. Ceramic implants

Correct Answer & Explanation

. Modular metallic implants

Explanation

Modular metallic implants are generally preferred for radial head replacement in acute fracture settings. They allow for independent adjustment of head size, stem diameter, and neck length, enabling the surgeon to precisely restore radial length, provide stability, and optimize contact with the capitellum. Monoblock implants offer less versatility. Bipolar implants have been used but have less favorable long-term outcomes than modular designs. Silicone implants are generally reserved for rheumatoid arthritis or reconstructive procedures, not acute fractures, and have issues with wear. Ceramic implants are less common for radial head.

Question 822

Topic: Elbow & Forearm

When assessing a radial head fracture, what radiographic view is essential to evaluate the relationship between the radial head and capitellum and to identify potential mechanical blocks?

. Anteroposterior (AP) view of the elbow
. Lateral view of the elbow
. Oblique views (e.g., radiocapitellar view)
. Internal rotation view
. External rotation view

Correct Answer & Explanation

. Oblique views (e.g., radiocapitellar view)

Explanation

While AP and lateral views are standard, oblique views (specifically, the radiocapitellar view, also known as the radial head-capitellum view or Greenspan view) are crucial for thoroughly evaluating radial head fractures. These views help to unmask subtle displacement, depression, or mechanical blocks that might be obscured on standard AP or lateral projections, by rotating the forearm. They provide an 'en face' view of the radial head articular surface.

Question 823

Topic: Elbow & Forearm

A 35-year-old female presents with a Mason-Johnston Type II radial head fracture with 2mm displacement but no mechanical block. She is able to fully pronate and supinate. What is the most appropriate initial management?

. Open reduction and internal fixation (ORIF)
. Radial head replacement
. Sling immobilization for 1 week followed by early active range of motion
. Radial head excision
. Long arm cast for 4 weeks

Correct Answer & Explanation

. Sling immobilization for 1 week followed by early active range of motion

Explanation

For a Mason-Johnston Type II radial head fracture with minimal displacement (2mm) andno mechanical blockto forearm rotation, non-operative management with a brief period of immobilization (e.g., 1 week in a sling for comfort) followed by early active range of motion is often appropriate. Surgical intervention (ORIF, replacement, excision) is indicated if there's significant displacement, comminution, mechanical block, or associated instability. A long arm cast would lead to unnecessary stiffness.

Question 824

Topic: Elbow & Forearm

Which of the following describes the 'safe zone' for screw placement in the radial head when performing ORIF?

. The anterior 90-degree arc of the radial head
. The medial aspect adjacent to the coronoid
. The area that does not articulate with the capitellum or ulna throughout the arc of forearm rotation
. The posterior aspect, directly opposite the radial tuberosity
. The lateral-most aspect, adjacent to the lateral epicondyle

Correct Answer & Explanation

. The area that does not articulate with the capitellum or ulna throughout the arc of forearm rotation

Explanation

The 'safe zone' for hardware placement in the radial head refers to the area that does not articulate with the capitellum or the lesser sigmoid notch of the ulna throughout the full range of pronation and supination. This zone is typically a 110-degree arc on the radial head, often described as the posterolateral aspect when the forearm is in neutral. Placing hardware outside this zone risks impingement, pain, and loss of motion.

Question 825

Topic: Elbow & Forearm

What is the main advantage of using headless compression screws for fixation of radial head fractures?

. They are easier to remove if complications arise.
. They provide superior rotational stability compared to plates.
. They can be countersunk beneath the articular surface, reducing hardware prominence and impingement.
. They allow for earlier weight-bearing.
. They are significantly cheaper than other implants.

Correct Answer & Explanation

. They can be countersunk beneath the articular surface, reducing hardware prominence and impingement.

Explanation

Headless compression screws are advantageous for radial head fractures because they can be fully countersunk beneath the articular cartilage. This minimizes the risk of hardware prominence, which can lead to impingement on the capitellum or trochlea during forearm rotation, causing pain and limiting motion. They provide good compression but not necessarily superior rotational stability compared to plates. They are not always easier to remove or allow for earlier weight-bearing uniquely. Cost is not the primary surgical driver.

Question 826

Topic: Elbow & Forearm

When performing ORIF of a radial head fracture, what type of approach may risk the posterolateral rotatory stability if not carefully repaired?

. Anterior (Henry) approach
. Medial approach
. Posterolateral (Kocher) approach
. Direct posterior approach
. Ulnar collateral ligament approach

Correct Answer & Explanation

. Posterolateral (Kocher) approach

Explanation

The posterolateral (Kocher) approach, while commonly used and safe for the PIN, involves detaching or splitting the anconeus muscle and reflecting the supinator. If the lateral collateral ligament complex, particularly the lateral ulnar collateral ligament (LUCL) origin, is compromised or not meticulously repaired during closure (or if it was already injured), it can destabilize the elbow against posterolateral rotatory forces. Care must be taken to repair the posterior capsule and anconeus for stability.

Question 827

Topic: Elbow & Forearm

In pediatric radial head fractures, what specific management consideration is crucial due to the open physis?

. Immediate radial head replacement
. Aggressive ORIF to prevent growth arrest
. Emphasis on conservative management and remodeling potential, especially for radial neck fractures
. Routine radial head excision
. Long-term antibiotic prophylaxis

Correct Answer & Explanation

. Emphasis on conservative management and remodeling potential, especially for radial neck fractures

Explanation

In pediatric radial head (and especially radial neck) fractures, conservative management is often emphasized due to the significant remodeling potential of the growing bone. Surgical intervention is typically reserved for highly displaced fractures or those with severe mechanical blocks. Radial head replacement or excision is rarely performed in children due to the presence of the open physis and potential for growth disturbance. Aggressive ORIF should be avoided if possible to prevent physeal injury, and long-term antibiotics are irrelevant.

Question 828

Topic: Elbow & Forearm

What clinical test helps assess lateral ulnar collateral ligament (LUCL) integrity in the context of an elbow injury suspected of posterolateral rotatory instability?

. Valgus stress test
. Varus stress test
. Pivot shift test of the elbow (e.g., gravity-assisted posterior drawer)
. Milking maneuver
. Cozen's test

Correct Answer & Explanation

. Pivot shift test of the elbow (e.g., gravity-assisted posterior drawer)

Explanation

The pivot shift test of the elbow (often performed gravity-assisted or with a specific maneuver to apply valgus and supination moment) is used to assess for posterolateral rotatory instability (PLRI), which is primarily caused by injury to the lateral ulnar collateral ligament (LUCL). Valgus stress tests the MCL, varus tests the LCL complex broadly (including LUCL but less specific for PLRI), milking maneuver tests MCL, and Cozen's test is for lateral epicondylitis.

Question 829

Topic: Elbow & Forearm

Which of the following surgical complications is specifically related to the removal of the radial head?

. Posterior interosseous nerve palsy
. Heterotopic ossification
. Proximal migration of the radius
. Ulnar nerve irritation
. Infection

Correct Answer & Explanation

. Proximal migration of the radius

Explanation

Proximal migration of the radius is a specific complication related to radial head excision. The radial head contributes to longitudinal forearm stability. Its removal without replacement, especially if the interosseous membrane is also compromised, allows the radius to migrate proximally, leading to changes in forearm mechanics, DRUJ incongruity, and often chronic wrist pain and dysfunction. While other complications can occur, proximal migration is characteristic of radial head excision.

Question 830

Topic: Elbow & Forearm

What is the most common cause of early post-operative stiffness following radial head fracture fixation?

. Infection
. Nerve injury
. Hardware prominence and impingement
. Aseptic loosening
. Non-union

Correct Answer & Explanation

. Hardware prominence and impingement

Explanation

Early post-operative stiffness following radial head fracture fixation is very commonly caused by hardware prominence and impingement. If screws or plates are not properly countersunk or are placed outside the 'safe zone,' they can impinge on the capitellum or ulna during motion, causing pain and restricting range of motion. While infection, nerve injury, and non-union can cause issues, mechanical impingement is a leading cause of early stiffness directly related to fixation.

Question 831

Topic: Elbow & Forearm

What is the most crucial step in managing an Essex-Lopresti lesion involving a radial head fracture?

. Sling immobilization for 6 weeks
. Excision of the radial head without replacement
. Restoration of radial length and stabilization of the DRUJ (typically with radial head replacement)
. Isolated repair of the interosseous membrane
. Primary elbow arthrodesis

Correct Answer & Explanation

. Restoration of radial length and stabilization of the DRUJ (typically with radial head replacement)

Explanation

The most crucial step in managing an Essex-Lopresti lesion is the restoration of radial length and stabilization of the distal radio-ulnar joint (DRUJ). This is typically achieved with a radial head replacement. Simply excising the radial head would exacerbate the proximal migration and DRUJ instability. Isolated repair of the interosseous membrane is often insufficient without addressing radial length. Sling immobilization and arthrodesis are not appropriate for this severe, unstable injury pattern.

Question 832

Topic: Elbow & Forearm

What is the primary stabilizer preventing valgus stress at the elbow?

. Lateral ulnar collateral ligament (LUCL)
. Annular ligament
. Anterior bundle of the medial collateral ligament (MCL)
. Radial head
. Oblique cord

Correct Answer & Explanation

. Anterior bundle of the medial collateral ligament (MCL)

Explanation

The anterior bundle of the medial collateral ligament (MCL) is the primary static stabilizer preventing valgus stress at the elbow, particularly from 30 to 120 degrees of flexion. The radial head acts as a secondary valgus stabilizer, providing a bony buttress, especially when the MCL is compromised. The LUCL stabilizes against varus and posterolateral rotatory instability. The annular ligament stabilizes the PRUJ.

Question 833

Topic: Elbow & Forearm

In a pediatric Monteggia Type I fracture, what is the role of the annular ligament in maintaining radial head stability after reduction?

. It is usually completely torn and contributes minimally to stability.
. It often remains intact or partially torn and provides crucial stability after reduction.
. Its primary role is to resist valgus stress, not radial head displacement.
. It primarily functions to attach the radius to the ulna, not the humerus.
. It becomes redundant after ulnar fixation and is not essential.

Correct Answer & Explanation

. It often remains intact or partially torn and provides crucial stability after reduction.

Explanation

In Monteggia fractures, particularly in children, the annular ligament often remains intact but may be stretched or partially torn. After reduction of the ulnar fracture, the tension in the interosseous membrane and the intact or partially intact annular ligament are crucial for stabilizing the radial head. The integrity of the annular ligament is a key factor in achieving and maintaining a stable closed reduction in children. If the annular ligament is completely torn or entrapped in the joint (buttonholing), it can prevent concentric reduction and necessitate open repair/reconstruction. Its role is indeed vital for maintaining the reduction of the radial head.

Question 834

Topic: Elbow & Forearm

A 10-year-old child presents with a Monteggia Type I injury. After attempts at closed reduction under sedation, the radial head remains persistently dislocated anteriorly. What is the most appropriate next step?

. Repeat closed reduction under general anesthesia with more forceful manipulation
. Proceed with open reduction and internal fixation (ORIF) of the ulna and radial head
. Immobilize in a long-arm cast and re-evaluate in one week
. Order an MRI to identify soft tissue obstruction
. Perform a radial head excision

Correct Answer & Explanation

. Proceed with open reduction and internal fixation (ORIF) of the ulna and radial head

Explanation

If closed reduction attempts for a pediatric Monteggia fracture are unsuccessful, further forceful manipulation is not recommended as it can cause iatrogenic damage. The next step is generally open reduction. The most common cause of irreducible radial head dislocation in children is soft tissue interposition, typically the annular ligament or joint capsule, preventing concentric reduction. Open reduction allows for removal of the obstructing tissue and direct reduction of the radial head, often followed by repair of the annular ligament if necessary, and fixation of the ulnar fracture. An MRI might confirm soft tissue obstruction but usually is not needed if reduction fails; direct surgical exploration is often more efficient. Radial head excision is not indicated in an acute pediatric setting.

Question 835

Topic: Elbow & Forearm

When managing a Monteggia fracture in an adult, what is the primary goal of ulnar fracture fixation?

. To achieve a non-union of the ulna for increased forearm mobility
. To provide sufficient stability to allow for immediate radial head excision
. To achieve anatomical reduction and stable fixation, which typically allows spontaneous reduction of the radial head
. To primarily reduce the radial head, with ulnar fixation being secondary
. To facilitate early weight-bearing through the elbow

Correct Answer & Explanation

. To achieve anatomical reduction and stable fixation, which typically allows spontaneous reduction of the radial head

Explanation

For adult Monteggia fractures, the primary goal of ulnar fracture fixation is to achieve anatomical reduction and stable internal fixation. Correcting the ulnar length, angulation, and rotation is crucial. Once the ulna is anatomically restored and fixed, the intact interosseous membrane and often an intact or only partially torn annular ligament usually cause the radial head to spontaneously reduce and become stable. Therefore, direct surgical intervention on the radial head is often not necessary unless it remains irreducible after stable ulnar fixation. The other options are either incorrect goals or not the primary aim of ulnar fixation in this context.

Question 836

Topic: Elbow & Forearm

What is a potential long-term complication specifically associated with missed or chronic Monteggia fractures in children?

. Early onset of osteoarthritis in the wrist
. Development of Madelung's deformity
. Progressive cubitus varus deformity
. Recurrent radial head dislocation due to an attenuated or absent annular ligament
. Carpal tunnel syndrome

Correct Answer & Explanation

. Recurrent radial head dislocation due to an attenuated or absent annular ligament

Explanation

Missed or chronic Monteggia fractures in children are associated with significant long-term morbidity, most notably recurrent or persistent radial head dislocation. If the radial head is not reduced and stabilized acutely, the annular ligament becomes attenuated, stretched, or completely non-functional, leading to recurrent instability or persistent dislocation. This can result in pain, limited forearm rotation, and premature degenerative changes. Madelung's deformity is a distal radial growth plate issue. Cubitus varus is associated with supracondylar fractures. Early wrist osteoarthritis and carpal tunnel syndrome are not primary long-term sequelae of chronic Monteggia per se.

Question 837

Topic: Elbow & Forearm

After fixation of an adult Monteggia Type I fracture, the radial head remains stubbornly dislocated. Intra-operatively, what structure is most likely preventing reduction?

. Triceps tendon
. Brachialis muscle
. Biceps tendon
. Annular ligament or joint capsule
. Medial collateral ligament

Correct Answer & Explanation

. Annular ligament or joint capsule

Explanation

If the radial head remains stubbornly dislocated after stable anatomical fixation of the ulnar fracture in a Monteggia injury, it typically indicates a mechanical block to reduction. The most common obstructing structures are a torn and entrapped annular ligament (often 'buttonholed' into the joint) or a portion of the joint capsule. These soft tissues can prevent the radial head from re-engaging with the capitellum. The other listed structures (triceps, brachialis, biceps, MCL) are not typically interposed in a way that prevents concentric radial head reduction.

Question 838

Topic: Elbow & Forearm
A 9-year-old with a Monteggia Type III fracture undergoes closed reduction and casting. At the 2-week follow-up, radiographs show slight anterior subluxation of the radial head, but the ulnar fracture is well-aligned. The child has mild pain but a good range of pronation/supination. What is the most appropriate management?
. Immediate surgical open reduction and annular ligament repair
. Re-manipulation and re-casting with the forearm in supination
. Continue current cast immobilization and re-evaluate at 4 weeks
. Remove cast and initiate early physiotherapy to prevent stiffness
. Convert to a hinge brace for early motion

Correct Answer & Explanation

. Immediate surgical open reduction and annular ligament repair

Explanation

Persistent subluxation or redislocation of the radial head after initial reduction and casting, even if 'slight,' necessitates further intervention, especially in a child. In this scenario, slight anterior subluxation of a Type III injury (which is typically a lateral/anterolateral dislocation) is problematic and indicates instability. A persistently subluxated radial head is prone to further displacement and can lead to long-term issues like limited rotation and premature arthritis. Given the initial failure, the most appropriate step is usually open reduction to directly reduce the radial head, assess for and remove any soft tissue interposition (e.g., annular ligament, capsule), and repair the annular ligament if compromised, along with definitive ulnar fixation. Re-manipulation is less likely to succeed if the initial attempt failed to hold, and simply continuing the cast risks a chronic subluxation. Early physiotherapy or a hinge brace would not address the instability.

Question 839

Topic: Elbow & Forearm
What is the primary purpose of immobilizing a pediatric Monteggia Type I fracture in supination after successful closed reduction?
. To facilitate nursing care
. To tighten the interosseous membrane and annular ligament, stabilizing the anteriorly dislocated radial head
. To prevent ulnar nerve compression
. To reduce swelling and pain more effectively
. To encourage early bone healing of the ulna

Correct Answer & Explanation

. To tighten the interosseous membrane and annular ligament, stabilizing the anteriorly dislocated radial head

Explanation

For a Monteggia Type I fracture (anterior radial head dislocation), the radial head is reduced, and the forearm is typically immobilized in full supination. This position helps to tighten the interosseous membrane and the often partially intact annular ligament, creating tension that stabilizes the radial head and prevents its anterior redislocation. For Type III (lateral dislocation), pronation is often used. The other options are either incorrect or secondary benefits.

Question 840

Topic: Elbow & Forearm

What anatomical structure is primarily responsible for preventing the superior migration of the radial head relative to the ulna?

. Medial collateral ligament
. Lateral collateral ligament
. Annular ligament
. Interosseous membrane
. Capsular ligaments of the elbow

Correct Answer & Explanation

. Interosseous membrane

Explanation

The interosseous membrane (IOM) is the primary anatomical structure preventing superior migration of the radial head. It acts as a strong stabilizer, transmitting axial loads from the radius to the ulna. If the IOM is severely disrupted, typically in conjunction with a radial head fracture and distal radioulnar joint (DRUJ) dislocation (as seen in an Essex-Lopresti injury), the radius can migrate proximally, leading to ulnar impaction syndrome at the wrist. The annular ligament encircles the radial head, preventing lateral and anterior/posterior displacement, but is not the primary restraint against superior migration.

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