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9. Shoulder and Elbow MCQs

Practice Set 149 of 197

This practice set contains high-yield board review questions covering key concepts in 9. Shoulder and Elbow. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 2961

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 2962

Topic: 9. Shoulder and Elbow

What is the most crucial imaging finding to avoid missing a Monteggia fracture in a patient with a proximal ulnar fracture?

. Oblique views of the elbow
. Stress views of the ulna
. Anterior-posterior and lateral views of the entire elbow joint
. Comparison views of the contralateral elbow
. MRI of the elbow

Correct Answer & Explanation

. Anterior-posterior and lateral views of the entire elbow joint

Explanation

The most critical step in diagnosing a Monteggia fracture is ensuring that the radiographs include both the elbow and wrist joints in their entirety, particularly accurate AP and lateral views of the elbow. The radial head dislocation can be subtle, especially in children, and may be missed if only the ulnar fracture is in focus. A line drawn along the axis of the radial shaft should always pass through the capitellum in all views. If this relationship is disrupted, radial head dislocation is present. Oblique views and stress views can be supplementary but are not primary for initial diagnosis. MRI is typically reserved for evaluating soft tissue injuries or complex cases, not for initial screening of acute trauma.

Question 2963

Topic: 9. Shoulder and Elbow

Which of the following is an absolute indication for open reduction of the radial head in a pediatric Monteggia fracture?

. Persistent pain after closed reduction
. Failure of closed reduction after 2 attempts
. Radial head subluxation
. Associated nerve palsy
. Inability to achieve full elbow extension

Correct Answer & Explanation

. Failure of closed reduction after 2 attempts

Explanation

Failure of closed reduction after one or, at most, two gentle attempts is an absolute indication for open reduction of the radial head in a pediatric Monteggia fracture. Repeated forceful attempts at closed reduction can cause further damage to the articular cartilage or nerve structures. The most common reason for failed closed reduction is soft tissue interposition (e.g., annular ligament, joint capsule) preventing concentric reduction, which requires surgical intervention to clear the obstruction. Persistent pain, subluxation (as opposed to dislocation), nerve palsy (unless progressive or non-recovering), or limited elbow extension are not immediate absolute indications for open reduction of the radial head itself, although they may influence overall management or indicate other issues.

Question 2964

Topic: 9. Shoulder and Elbow

What is the typical mechanism of injury for a Bado Type I Monteggia fracture?

. Direct blow to the posterior aspect of the elbow, with the forearm in supination
. Fall onto an outstretched hand with the forearm in hyperpronation, causing excessive valgus force
. Fall onto an outstretched hand with the forearm in hyperpronation, causing axial loading and excessive pronation stress
. Direct blow to the lateral aspect of the elbow, causing varus stress
. Hyperextension injury of the elbow

Correct Answer & Explanation

. Fall onto an outstretched hand with the forearm in hyperpronation, causing axial loading and excessive pronation stress

Explanation

Bado Type I Monteggia fractures (anterior radial head dislocation with anteriorly angulated ulnar fracture) typically result from a fall on an outstretched hand with the forearm in hyperpronation. The axial load and pronation stress cause the ulna to fracture, and the radial head dislocates anteriorly relative to the capitellum. The posterior interosseous nerve (PIN) is particularly vulnerable in this type of injury due to stretching during the pronation and dislocation mechanism. Direct blows or valgus/varus stresses are associated with other elbow injuries.

Question 2965

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 2966

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 2967

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 2968

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 2969

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 2970

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 2971

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 2972

Topic: 9. Shoulder and Elbow

A Monteggia fracture in a child that is missed and not diagnosed until weeks or months later often presents with what characteristic deformity or functional deficit?

. Fixed elbow extension deformity
. Valgus deformity of the elbow
. Cubitus varus deformity
. Progressive loss of forearm rotation (pronation and supination)
. Carpal instability

Correct Answer & Explanation

. Progressive loss of forearm rotation (pronation and supination)

Explanation

A missed or chronic Monteggia fracture in a child will most commonly lead to progressive loss of forearm rotation, particularly pronation and supination. The persistently dislocated radial head acts as a mechanical block to normal rotational movements of the forearm. Over time, adaptive changes can occur in the joint and soft tissues, leading to a stiff, painful elbow with severely limited motion. Other deformities might be present but the loss of rotation is a hallmark functional deficit. Fixed extension deformity is less common, and valgus/varus deformities are associated with other types of elbow fractures. Carpal instability is not a direct consequence.

Question 2973

Topic: 9. Shoulder and Elbow

Which surgical approach is generally preferred for open reduction of the radial head in a chronically dislocated Monteggia Type I fracture in an adult?

. Posterior approach to the elbow
. Medial approach to the elbow
. Anterolateral approach (Kaplan's approach) or lateral approach to the radial head
. Posteromedial approach
. Direct anterior approach

Correct Answer & Explanation

. Anterolateral approach (Kaplan's approach) or lateral approach to the radial head

Explanation

For open reduction of the radial head, especially in chronic Type I (anterior dislocation) Monteggia injuries or when there's an irreducible radial head, an anterolateral or direct lateral approach (e.g., Kaplan's approach) is generally preferred. This allows direct visualization and access to the radial head and the annular ligament. It provides excellent exposure for removing interposed tissue and performing annular ligament repair or reconstruction. A posterior approach is for posterior dislocations/fractures, medial for medial epicondyle/ulnar nerve, and anterior approaches carry higher risks to neurovascular structures, particularly the PIN.

Question 2974

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.

Question 2975

Topic: 9. Shoulder and Elbow

What is the significance of the 'anterior humeral line' in the radiographic assessment of a Monteggia fracture in a child?

. It helps identify posterior displacement of the ulna.
. It helps assess the rotation of the radial head.
. It should pass through the middle third of the capitellum; disruption suggests supracondylar or radial head fracture/dislocation.
. It indicates the extent of soft tissue swelling around the elbow.
. It is primarily used for wrist injuries, not elbow.

Correct Answer & Explanation

. It should pass through the middle third of the capitellum; disruption suggests supracondylar or radial head fracture/dislocation.

Explanation

The anterior humeral line is drawn along the anterior cortex of the humerus on a lateral elbow radiograph. In a normal elbow, this line should bisect or pass through the middle third of the capitellum. If the line does not pass through the capitellum or passes too anteriorly/posteriorly, it can indicate a supracondylar fracture with displacement of the capitellum or, less commonly, can be distorted by a radial head dislocation. While not specific to Monteggia, its assessment is part of a comprehensive elbow radiograph interpretation and can help identify subtle bony displacements, including potential issues related to the radiocapitellar articulation.

Question 2976

Topic: Elbow & Forearm

Which statement best describes the 'line of sight' rule in assessing radial head alignment on radiographs?

. A line through the epicondyles must be parallel to the joint line.
. A line drawn through the center of the radial shaft should always pass through the capitellum in all radiographic views.
. A line along the anterior humerus must intersect the coronoid process.
. A line through the olecranon must align with the ulnar shaft.
. A line from the radial head to the wrist must be straight.

Correct Answer & Explanation

. A line drawn through the center of the radial shaft should always pass through the capitellum in all radiographic views.

Explanation

The 'line of sight' or radiocapitellar line rule is a fundamental principle in assessing elbow radiographs for radial head dislocation. A line drawn through the center of the radial shaft, regardless of the degree of elbow flexion or forearm rotation, should always pass through the center of the capitellum. If this line does not intersect the capitellum, it confirms a radial head dislocation. This rule is crucial for identifying Monteggia fractures, as subtle radial head dislocations can be easily missed.

Question 2977

Topic: Elbow & Forearm

What surgical consideration is paramount when performing open reduction and internal fixation of an adult Monteggia Type II fracture?

. Ensuring minimal incision length to prevent HO
. Avoiding injury to the ulnar nerve due to its proximity to the posterior approach
. Aggressive radial head excision to prevent recurrent dislocation
. Only fixing the ulna and leaving the radial head to reduce spontaneously, regardless of residual displacement
. Focusing on the radial head first, then the ulna

Correct Answer & Explanation

. Avoiding injury to the ulnar nerve due to its proximity to the posterior approach

Explanation

For a Monteggia Type II fracture, a posterior approach is often utilized to access the ulnar shaft fracture and facilitate posterior radial head reduction. During a posterior approach, the ulnar nerve is at risk, particularly as it passes through the cubital tunnel. Therefore, careful identification, protection, and potentially anterior transposition of the ulnar nerve are paramount surgical considerations to prevent iatrogenic injury. While minimizing incision length is good practice, it's not paramount in preventing HO (which is multifactorial). Radial head excision is not a primary step. The ulna fixation is still primary, and spontaneous reduction of the radial head is expected after stable ulnar fixation, but persistent dislocation requires open reduction of the radial head. Focusing on the radial head first is incorrect; the ulna is key.

Question 2978

Topic: Elbow & Forearm

What is the most critical element to confirm on post-reduction radiographs for a Monteggia fracture?

. Alignment of the ulnar fracture fragments
. Absence of a fat pad sign
. Concentric reduction of the radial head relative to the capitellum
. Absence of associated hand fractures
. Adequate length of the forearm bones

Correct Answer & Explanation

. Concentric reduction of the radial head relative to the capitellum

Explanation

While proper ulnar alignment and overall forearm length are important, the most critical element to confirm on post-reduction radiographs for a Monteggia fracture is the concentric reduction of the radial head relative to the capitellum. A persistent radial head dislocation, even if the ulna is well-aligned, will lead to poor outcomes, pain, stiffness, and long-term instability. The 'line of sight' rule (a line through the radial shaft passing through the capitellum) must be satisfied on all views. The absence of a fat pad sign merely indicates resolution of swelling, and associated hand fractures are a separate concern.

Question 2979

Topic: Elbow & Forearm

In a skeletally immature patient with an acute Monteggia Type I injury, which treatment modality is preferred if the radial head reduces concentrically with closed reduction and the ulnar fracture is stable?

. ORIF of the ulna with a plate and screws
. External fixation
. Long-arm cast immobilization with the elbow flexed and forearm supinated
. Radial head excision
. Hinge brace for early motion

Correct Answer & Explanation

. Long-arm cast immobilization with the elbow flexed and forearm supinated

Explanation

For acute Monteggia Type I injuries in skeletally immature patients (children), if a concentric reduction of the radial head can be achieved and maintained by closed means, and the ulnar fracture is stable (e.g., greenstick or plastic deformation), then long-arm cast immobilization is the preferred treatment. The elbow is typically flexed to 90 degrees and the forearm in full supination to stabilize the anteriorly dislocated radial head. Surgical fixation (ORIF) is reserved for unstable ulnar fractures or irreducible radial head dislocations. Radial head excision is contraindicated in children. Hinge braces are not appropriate for initial stabilization.

Question 2980

Topic: Elbow & Forearm

What is a potential serious consequence of a chronic, unreduced radial head dislocation in a child following a Monteggia injury?

. Premature closure of the distal radial physis
. Development of a valgus elbow deformity
. Progressive cubitus varus
. Significant pain, decreased forearm rotation, and early degenerative changes in the radiocapitellar joint
. Spontaneous reduction over time with continued growth

Correct Answer & Explanation

. Significant pain, decreased forearm rotation, and early degenerative changes in the radiocapitellar joint

Explanation

A chronic, unreduced radial head dislocation in a child following a Monteggia injury is a serious issue. It will not spontaneously reduce and will lead to significant long-term morbidity, including chronic pain, severely restricted forearm rotation (pronation/supination), and ultimately early degenerative changes (arthrosis) of the radiocapitellar joint due to abnormal joint mechanics. It can also lead to secondary deformity. Premature closure of the distal radial physis is not directly related. Valgus or varus deformities are less common primary sequelae than loss of rotation and degenerative changes.

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