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Elbow & Forearm MCQs

Practice Set 41 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 801

Topic: Elbow & Forearm

In a patient with Multiple Hereditary Exostoses (MHE), which of the following forearm deformities is most characteristic of the 'Bessel-Hagen' deformity?

. Radial shortening with ulnar translocation of the carpus
. Ulnar shortening, increased radial bow, and progressive radial head dislocation
. Madelung deformity with volar-ulnar tilt of the distal radius
. Isolated hypertrophy of the radial styloid
. Synostosis of the proximal radius and ulna

Correct Answer & Explanation

. Ulnar shortening, increased radial bow, and progressive radial head dislocation

Explanation

Correct Answer: BThe Bessel-Hagen deformity in MHE is characterized by disproportionate shortening of the ulna (due to its smaller diameter and greater relative growth plate involvement), which leads to secondary bowing of the radius, ulnar tilt of the distal radial articular surface, and often, proximal translocation (dislocation) of the radial head.

Question 802

Topic: Elbow & Forearm
Which of the following describes a capitellar fracture according to the Bryan and Morrey classification?
. Type I: Coronal shear fracture of the capitellum with significant displacement
. Type II: Fracture involving both the capitellum and the trochlea (bicondylar)
. Type III: Fracture of the entire capitellum with a large amount of lateral epicondyle
. Type IV: Comminuted fracture of the entire distal humerus
. Type I: Coronal shear fracture of the capitellum without displacement

Correct Answer & Explanation

. Type I: Coronal shear fracture of the capitellum with significant displacement

Explanation

The Bryan and Morrey classification is commonly used for capitellar fractures. Type I is a complete coronal shear fracture of the capitellum that is displaced. Type II (Hahn-Steinthal) is a larger fragment including subchondral bone but often nondisplaced. Type III (Kocher-Lorenz) is an articular cartilage-only fracture. Type IV is for fractures involving the trochlea as well (Cunha-Bryan).

Question 803

Topic: Elbow & Forearm
Which of the following ligamentous structures is considered the primary static stabilizer against varus stress in the elbow?
. Anterior bundle of the medial ulnar collateral ligament (MUCL)
. Lateral ulnar collateral ligament (LUCL)
. Radial collateral ligament (RCL)
. Posterior bundle of the medial ulnar collateral ligament (MUCL)
. Annular ligament

Correct Answer & Explanation

. Radial collateral ligament (RCL)

Explanation

The Radial Collateral Ligament (RCL) complex, specifically the Radial Collateral Ligament proper, is the primary static stabilizer against varus stress. The Anterior Bundle of the Medial Ulnar Collateral Ligament (MUCL) is the primary stabilizer against valgus stress. The Lateral Ulnar Collateral Ligament (LUCL) is critical for posterolateral rotatory stability, preventing subluxation of the ulna and radius from the humerus. The Annular ligament stabilizes the radial head against the ulna but is not a primary varus stabilizer for the humeroulnar joint. The posterior bundle of the MUCL contributes to valgus stability but is less critical than the anterior bundle.

Question 804

Topic: Elbow & Forearm

A patient presents with an elbow dislocation associated with a radial head fracture and a coronoid process fracture. This constellation of injuries is classically termed a 'terrible triad' injury. Which aspect of this injury typically dictates the need for surgical intervention and directly impacts the stability of the elbow after reduction?

. The extent of the radial head comminution.
. The degree of soft tissue swelling.
. The presence of an associated ulnar nerve palsy.
. The integrity of the lateral ulnar collateral ligament (LUCL) complex.
. The specific location and size of the coronoid fracture.

Correct Answer & Explanation

. The integrity of the lateral ulnar collateral ligament (LUCL) complex.

Explanation

While all components contribute to the 'terrible triad,' the posterolateral rotatory instability caused by disruption of the lateral ulnar collateral ligament (LUCL) complex is the fundamental issue that dictates the need for surgical stabilization and affects post-reduction stability. The LUCL is crucial in preventing posterolateral rotatory instability, which is a common pattern in terrible triad injuries. Coronoid fractures (especially involving the sublime tubercle) and radial head fractures contribute significantly to instability, but the LUCL injury is often the primary driver for surgical intervention to restore stability. Radial head comminution influences the choice of radial head management (repair vs. replacement), and swelling is a consequence, not a primary driver of instability. Ulnar nerve palsy is a potential complication but not the defining feature dictating stability management.

Question 805

Topic: Elbow & Forearm

A 60-year-old patient undergoes reduction of a posterior elbow dislocation. Post-reduction radiographs show excellent congruity. However, the elbow remains grossly unstable in all planes. What is the MOST likely underlying reason for this persistent instability?

. Inadequate muscle relaxation during reduction.
. Missed radial head fracture.
. Complete disruption of both medial and lateral collateral ligament complexes.
. Undiagnosed osteochondral fragment within the joint.
. Early development of heterotopic ossification.

Correct Answer & Explanation

. Complete disruption of both medial and lateral collateral ligament complexes.

Explanation

Gross instability in all planes after reduction of an elbow dislocation, despite good radiographic congruity, strongly suggests complete disruption of both the medial (ulnar) and lateral collateral ligament complexes. While other factors like radial head or coronoid fractures contribute to instability, isolated injuries to these structures typically result in more specific patterns of instability (e.g., posterolateral rotatory instability with LUCL injury, valgus instability with MUCL injury). When both major collateral complexes are significantly compromised, the elbow becomes globally unstable. Inadequate muscle relaxation (Option A) would hinder reduction, not cause post-reduction global instability. A missed radial head fracture (Option B) would lead to more specific instability patterns (posterolateral rotatory). An osteochondral fragment (Option D) might block reduction or cause mechanical symptoms but not global instability. Heterotopic ossification (Option E) is a late complication causing stiffness, not acute instability.

Question 806

Topic: Elbow & Forearm

What is the primary role of the coronoid process in elbow stability?

. It serves as the attachment point for the lateral collateral ligament.
. It acts as the primary bony block to valgus stress.
. It provides the main resistance to varus stress.
. It is a critical anterior buttress, preventing posterior subluxation of the ulna on the humerus.
. It enhances radial head articulation with the capitellum.

Correct Answer & Explanation

. It is a critical anterior buttress, preventing posterior subluxation of the ulna on the humerus.

Explanation

The coronoid process acts as a critical anterior buttress, preventing posterior subluxation and dislocation of the ulna relative to the humerus. Fractures of the coronoid process, especially larger fragments, significantly compromise elbow stability, particularly in conjunction with collateral ligament injuries. It is not the primary attachment for the lateral collateral ligament (Option A), nor is it the main bony block to valgus (Option B) or varus (Option C) stress (these are more related to the olecranon and radial head articulation with the capitellum, and the collateral ligaments). It does not primarily enhance radial head articulation (Option E), though it contributes to overall joint congruity.

Question 807

Topic: Elbow & Forearm

A patient presents with a 'terrible triad' injury of the elbow. Which surgical approach is generally preferred for addressing all components (radial head, coronoid, and lateral collateral ligament) in a single setting?

. Medial approach to address the coronoid and medial collateral ligament.
. Direct posterior approach to the olecranon.
. Posterolateral approach with conversion to a Kocher interval.
. Anterior approach to decompress the median nerve.
. Anconeus interval approach, avoiding muscle dissection.

Correct Answer & Explanation

. Posterolateral approach with conversion to a Kocher interval.

Explanation

For a terrible triad injury, a posterolateral approach (often via the Kocher interval between the anconeus and extensor carpi ulnaris) is generally preferred. This approach allows for excellent visualization and access to the radial head, the lateral ulnar collateral ligament (LUCL) for repair, and the coronoid process (especially anteromedial facets) can often be accessed through this approach, potentially through a window created in the anconeus muscle or by extending the interval. A medial approach (Option A) would not allow access to the radial head or LUCL. A direct posterior approach (Option B) is less ideal for radial head or LUCL. Anterior (Option D) or anconeus interval (Option E) approaches are less comprehensive for all components of the triad.

Question 808

Topic: Elbow & Forearm

What is the MOST critical biomechanical consequence of a lateral ulnar collateral ligament (LUCL) insufficiency in the elbow?

. Increased valgus instability.
. Increased varus instability.
. Posterolateral rotatory instability (PLRI).
. Increased anterior-posterior translation of the radial head.
. Loss of elbow flexion.

Correct Answer & Explanation

. Posterolateral rotatory instability (PLRI).

Explanation

Insufficiency or rupture of the lateral ulnar collateral ligament (LUCL) is the hallmark cause of posterolateral rotatory instability (PLRI) of the elbow. The LUCL originates from the lateral epicondyle and inserts on the supinator crest of the ulna, forming a sling that stabilizes the ulna and radius against posterolateral displacement from the humerus, especially during supination and valgus stress. It does not primarily cause valgus or varus instability directly (though secondary varus may result from severe PLRI). Anterior-posterior translation (Option D) or loss of flexion (Option E) are not direct consequences.

Question 809

Topic: Elbow & Forearm

A 70-year-old patient with osteoporosis sustains a posterior elbow dislocation with a highly comminuted radial head fracture that is not amenable to open reduction and internal fixation. What is the MOST appropriate management strategy for the radial head in this 'terrible triad' setting?

. Excision of the radial head to prevent impingement.
. Delay surgical intervention until soft tissue swelling resolves.
. Radial head arthroplasty with an appropriate implant.
. Long-term immobilization in a cast.
. Perform a wrist arthrodesis to offload the elbow.

Correct Answer & Explanation

. Radial head arthroplasty with an appropriate implant.

Explanation

In the setting of a terrible triad injury, a highly comminuted radial head fracture not amenable to repair necessitates restoration of the radial column length and joint congruity. Radial head arthroplasty with an appropriate implant (Option C) is generally the preferred method to achieve this, as it helps stabilize the elbow, especially in the context of a deficient LUCL and coronoid fracture. Excision of the radial head (Option A) is contraindicated in terrible triad injuries, as it further destabilizes the elbow and can lead to proximal migration of the radius and secondary wrist pain. Delaying surgery (Option B) is inappropriate for an acute complex injury. Long-term immobilization (Option D) leads to severe stiffness and does not address the instability. Wrist arthrodesis (Option E) is irrelevant.

Question 810

Topic: Elbow & Forearm

In the setting of a persistent valgus instability after elbow dislocation, which structure is MOST likely to be deficient or ruptured?

. Lateral ulnar collateral ligament (LUCL).
. Annular ligament.
. Anterior bundle of the medial ulnar collateral ligament (MUCL).
. Posterior bundle of the medial ulnar collateral ligament (MUCL).
. Radial collateral ligament (RCL).

Correct Answer & Explanation

. Anterior bundle of the medial ulnar collateral ligament (MUCL).

Explanation

The anterior bundle of the medial ulnar collateral ligament (MUCL) is the primary static stabilizer against valgus stress in the elbow. Its rupture or insufficiency will lead to valgus instability. The LUCL (Option A) causes posterolateral rotatory instability. The annular ligament (Option B) stabilizes the radial head to the ulna. The posterior bundle of the MUCL (Option D) also contributes to valgus stability but the anterior bundle is the primary restraint. The RCL (Option E) provides varus stability.

Question 811

Topic: Elbow & Forearm

A 25-year-old rugby player presents with a recent elbow dislocation. Post-reduction, the elbow is stable in full flexion but dislocates with pronation and extension, especially when a valgus stress is applied. Which specific ligament injury is MOST likely responsible for this instability pattern?

. Medial ulnar collateral ligament (MUCL) - anterior bundle.
. Lateral ulnar collateral ligament (LUCL).
. Radial collateral ligament (RCL).
. Annular ligament.
. Posterior bundle of the MUCL.

Correct Answer & Explanation

. Lateral ulnar collateral ligament (LUCL).

Explanation

The described instability pattern (dislocates with pronation, extension, and valgus stress) is classic for posterolateral rotatory instability (PLRI), which is caused by a rupture of the lateral ulnar collateral ligament (LUCL) complex. When the LUCL is disrupted, the radius and ulna subluxate posterolaterally on the humerus, particularly with the forearm in supination and the elbow in extension and valgus stress (often tested with a pivot shift maneuver). This pattern is not due to MUCL (Option A and E) which causes valgus instability, RCL (Option C) which causes varus instability, or annular ligament (Option D) which stabilizes the radial head to the ulna.

Question 812

Topic: Elbow & Forearm

What is the typical sequence of ligamentous disruption in a posterolateral rotatory instability (PLRI) injury of the elbow, starting with the least severe?

. Medial collateral ligament, anterior capsule, lateral collateral ligament.
. Lateral collateral ligament, anterior capsule, medial collateral ligament.
. Annular ligament, radial collateral ligament, medial collateral ligament.
. Coronoid process fracture, radial head fracture, lateral collateral ligament.
. Posterior capsule, anterior capsule, lateral collateral ligament.

Correct Answer & Explanation

. Lateral collateral ligament, anterior capsule, medial collateral ligament.

Explanation

The 'Horii-Morrey circle of instability' describes the typical pattern of soft tissue disruption in progressive posterolateral rotatory instability (PLRI), which is the most common form of elbow dislocation. The sequence starts laterally and progresses medially: 1) disruption of the lateral collateral ligament (LUCL/LCL complex), 2) disruption of the anterior and posterior capsule, and then 3) disruption of the medial collateral ligament (MUCL). Therefore, Option B is the correct representation of this sequence.

Question 813

Topic: Elbow & Forearm

When performing a surgical repair of the lateral ulnar collateral ligament (LUCL) for posterolateral rotatory instability, where is the most critical anatomical attachment point to recreate for stability?

. Capitellum.
. Lateral epicondyle.
. Radial head neck.
. Supinator crest of the ulna.
. Medial epicondyle.

Correct Answer & Explanation

. Lateral epicondyle.

Explanation

The lateral ulnar collateral ligament (LUCL) originates from the lateral epicondyle (Option B) of the humerus and inserts onto the supinator crest of the ulna (Option D), forming a 'sling' that prevents posterolateral rotatory displacement of the ulna. Therefore, to recreate stability, both the origin and insertion are critical. However, specifically the lateral epicondyle is where the complex originates, and a direct repair or reconstruction must re-attach or anchor here. The question asks for 'attachment point to recreate for stability', and the epicondyle is the origin. The supinator crest is the insertion. The LUCL is distinct from the radial collateral ligament that attaches to the annular ligament. Hence, the lateral epicondyle is the most critical anatomical point to recreate the proximal attachment.

Question 814

Topic: Elbow & Forearm

A patient is undergoing open reduction and internal fixation of a terrible triad injury. After coronoid and radial head fixation, the elbow remains unstable with a positive pivot shift test (posterolateral rotatory instability). What is the MOST crucial next step to restore stability?

. Apply an external fixator across the elbow.
. Perform a medial collateral ligament repair.
. Reinforce the anterior capsule.
. Perform a lateral ulnar collateral ligament (LUCL) repair or reconstruction.
. Consider radial head excision to decompress the joint.

Correct Answer & Explanation

. Perform a lateral ulnar collateral ligament (LUCL) repair or reconstruction.

Explanation

A positive pivot shift test after coronoid and radial head fixation indicates persistent posterolateral rotatory instability, which is primarily due to insufficiency of the lateral ulnar collateral ligament (LUCL) complex. Therefore, performing a lateral ulnar collateral ligament (LUCL) repair or reconstruction is the most crucial next step to restore stability in this scenario. While an external fixator (Option A) can be used as an adjunct, it is not the primary stabilizing procedure for the LUCL. Medial collateral ligament repair (Option B) addresses valgus instability, not PLRI. Reinforcing the anterior capsule (Option C) is less critical than addressing the LUCL. Radial head excision (Option D) would further destabilize the elbow.

Question 815

Topic: Elbow & Forearm

During closed reduction of a posterior elbow dislocation, one should avoid excessive force and hyperflexion primarily to prevent which complication?

. Ulnar nerve entrapment.
. Iatrogenic fracture of the coronoid or distal humerus.
. Radial head subluxation.
. Medial collateral ligament avulsion.
. Heterotopic ossification.

Correct Answer & Explanation

. Iatrogenic fracture of the coronoid or distal humerus.

Explanation

Excessive force, particularly with hyperflexion, during closed reduction can lead to iatrogenic fracture, most commonly of the coronoid process or distal humerus. It can also increase the risk of neurovascular injury. While ulnar nerve entrapment (Option A) can occur, it is often due to the initial injury or specific reduction maneuvers. Radial head subluxation (Option C) is a different pattern of instability. Medial collateral ligament avulsion (Option D) is more related to valgus stress. Heterotopic ossification (Option E) is a long-term complication, not an acute risk of reduction itself.

Question 816

Topic: Elbow & Forearm

In a patient with a terrible triad injury, after repairing the lateral ulnar collateral ligament (LUCL) and addressing the coronoid fracture, what is the MOST important consideration for managing a repairable radial head fracture?

. Excise the radial head to prevent stiffness.
. Perform immediate arthrodesis of the elbow.
. Achieve stable internal fixation with anatomical reduction to maintain radial length and joint congruity.
. Immobilize the elbow in full extension for 6 weeks.
. Replace the radial head with a metallic implant regardless of reparability.

Correct Answer & Explanation

. Achieve stable internal fixation with anatomical reduction to maintain radial length and joint congruity.

Explanation

For a repairable radial head fracture in a terrible triad injury, the MOST important consideration is to achieve stable internal fixation with anatomical reduction to maintain radial length and joint congruity. This contributes significantly to overall elbow stability by providing a buttress to the capitellum and helping to restore forearm mechanics. Excising the radial head (Option A) is contraindicated as it destabilizes the elbow. Arthrodesis (Option B) is a salvage procedure. Immobilization (Option D) leads to stiffness and may not maintain reduction. Replacing the radial head (Option E) is only for non-reparable fractures.

Question 817

Topic: Elbow & Forearm

A patient presents with a history of recurrent elbow dislocations. What is the MOST likely underlying anatomical deficiency?

. Weakness of the biceps brachii muscle.
. Chronic insufficiency of the medial ulnar collateral ligament (MUCL).
. Chronic insufficiency of the lateral ulnar collateral ligament (LUCL).
. Persistent radial head subluxation.
. Heterotopic ossification around the olecranon fossa.

Correct Answer & Explanation

. Chronic insufficiency of the lateral ulnar collateral ligament (LUCL).

Explanation

Recurrent elbow dislocations are most commonly associated with chronic insufficiency of the lateral ulnar collateral ligament (LUCL), leading to recurrent posterolateral rotatory instability (PLRI). This is because the LUCL is the primary restraint to posterolateral displacement of the ulna and radius from the humerus. While MUCL insufficiency (Option B) causes valgus instability, it is less commonly the primary cause of recurrent dislocation itself compared to LUCL. Muscle weakness (Option A), radial head subluxation (Option D), or HO (Option E) are not the primary underlying anatomical deficiencies for recurrent dislocations.

Question 818

Topic: Elbow & Forearm

A patient sustains a posterior elbow dislocation. During assessment, the physician notes an inability to fully supinate the forearm and a click with pronation. This may indicate an injury to which structure?

. Medial ulnar collateral ligament.
. Lateral ulnar collateral ligament (LUCL) complex.
. Annular ligament.
. Radial head.
. Brachialis muscle.

Correct Answer & Explanation

. Lateral ulnar collateral ligament (LUCL) complex.

Explanation

The inability to fully supinate and a click with pronation after an elbow dislocation may indicate an injury to the lateral ulnar collateral ligament (LUCL) complex, specifically the lateral collateral ligament. This pattern suggests posterolateral rotatory instability (PLRI) where the radial head and ulna pivot or subluxate posterolaterally. The LUCL is the primary restraint to PLRI. Medial ulnar collateral ligament (Option A) injury causes valgus instability. Annular ligament (Option C) injury leads to radial head subluxation but less commonly this specific pronation/supination click. Radial head (Option D) is bony, and brachialis muscle (Option E) is soft tissue but less specifically related to this click.

Question 819

Topic: Elbow & Forearm

What is the typical management approach for an acutely dislocated radial head with an intact ulna (isolated radial head dislocation)?

. Closed reduction followed by long arm cast in supination.
. Open reduction and internal fixation of the radial head.
. Radial head excision to prevent re-dislocation.
. Closed reduction followed by long arm cast in pronation.
. No specific treatment, as it is a stable injury.

Correct Answer & Explanation

. Closed reduction followed by long arm cast in supination.

Explanation

Isolated radial head dislocations (without an ulnar fracture, often referred to as a congenital or developmental issue, or potentially an acute traumatic entity in specific scenarios) are rare in adults and usually unstable after reduction. However, a pure traumatic isolated radial head dislocation is extremely rare. More commonly, radial head dislocations are associated with ulnar shaft fractures (Monteggia lesion). If it's apureisolated radial head dislocation, closed reduction is attempted, but stability is a major issue. For traumatic isolated radial head dislocation without associated ulnar fracture, which implies tearing of the annular ligament, stabilization of the radial head via closed reduction followed by a long arm cast insupinationis typically attempted to reduce stress on the annular ligament and the interosseous membrane. However, if irreducible or unstable, surgical repair of the annular ligament might be needed. Option A: Closed reduction followed by long arm cast insupinationis chosen to maintain reduction by tightening the interosseous membrane. Option D, pronation, would loosen it. This assumes an acute traumatic injury. If it is a chronic or congenital dislocation, management is different. This question is tricky given the 'isolated' aspect. Let's re-evaluate. Most 'isolated' radial head dislocations are congenital. Traumatic isolated radial head dislocation implies annular ligament rupture, and closed reduction with supination is the typical initial treatment to attempt to re-engage the radial head and allow annular ligament healing. If irreducible or unstable, then surgery for annular ligament repair is indicated. Radial head excision (Option C) is destabilizing. Therefore, closed reduction and immobilization in supination is the most appropriateinitialmanagement for an acute traumatic isolated radial head dislocation.

Question 820

Topic: Elbow & Forearm
A 70-year-old sedentary patient presents with a Mason-Johnston Type III radial head fracture with severe comminution. He is not keen on extensive surgery. What is a reasonable management option to consider, accepting potential trade-offs?
. Open reduction and internal fixation (ORIF)
. Radial head replacement
. Radial head excision
. Primary elbow arthrodesis
. Conservative management with a long arm cast

Correct Answer & Explanation

. Radial head excision

Explanation

For elderly, sedentary patients with severely comminuted radial head fractures (Type III or IV) who are not candidates for ORIF or do not desire more extensive surgery like radial head replacement, radial head excision can be a reasonable option. While it carries the risk of proximal radial migration and DRUJ issues, in low-demand individuals, it can provide pain relief and improve motion with acceptable functional outcomes.

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