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Wrist & Carpus MCQs

Practice Set 22 of 33

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

Question 421

Topic: Wrist & Carpus

After fixation of a distal radius fracture, dynamic instability of the distal radioulnar joint (DRUJ) is suspected. Which maneuver specifically tests for this?

. Ballottement test
. Scaphoid shift test
. DRUJ stress test (provocative rotation)
. Grind test
. Piano key test

Correct Answer & Explanation

. DRUJ stress test (provocative rotation)

Explanation

Dynamic instability of the DRUJ refers to abnormal laxity or subluxation during active pronation and supination. A DRUJ stress test involves stabilizing the radius and actively or passively rotating the forearm while palpating for excessive translation, crepitus, or pain at the DRUJ. The Piano Key test assesses static dorsal/volar laxity of the ulna at rest. The Ballottement test (or radioulnar shear test) assesses static DRUJ stability. Scaphoid shift is for scapholunate instability, and Grind test is for CMC arthritis.

Question 422

Topic: Wrist & Carpus

An unstable distal radius fracture with a displaced ulnar styloid base fracture is treated with volar plating of the radius. Post-operatively, the DRUJ is found to be stable. What is the most appropriate management for the ulnar styloid fracture?

. Surgical fixation of the ulnar styloid with tension band wiring
. Excision of the ulnar styloid
. Non-operative management with observation
. Immobilization in a long-arm cast
. Fusion of the DRUJ

Correct Answer & Explanation

. Non-operative management with observation

Explanation

The primary role of the ulnar styloid in the context of DRUJ stability is through its attachments to the TFCC, particularly the dorsal and volar radioulnar ligaments. If the DRUJ is stable after radius fixation, even with a displaced ulnar styloid base fracture, non-operative management with observation is typically sufficient. The ulnar styloid fracture often heals without intervention, and its fixation is usually indicated only if it's large, significantly displaced, and contributes to DRUJ instability, or if it causes symptomatic non-union. Surgical fixation of the ulnar styloid is not routine if the DRUJ is stable.

Question 423

Topic: Wrist & Carpus

To minimize the risk of Extensor Pollicis Longus (EPL) rupture when performing dorsal plating for distal radius fractures, which surgical technique is most critical?

. Using a long, multi-hole plate
. Placing the plate directly over Lister's tubercle
. Ensuring the plate is low-profile and countersunk
. Avoiding bone graft placement
. Aggressive early range of motion

Correct Answer & Explanation

. Ensuring the plate is low-profile and countersunk

Explanation

EPL rupture after dorsal plating is often due to attrition over a prominent plate or screw heads, especially at Lister's tubercle. Using low-profile plates and ensuring the plate is countersunk (recessed into the bone) to minimize prominence above the bone surface is crucial. Placing the plate directly over Lister's tubercle increases risk. A long plate may be needed, but its profile is key. Bone graft doesn't directly prevent EPL rupture. Aggressive early range of motion without a smooth surface can exacerbate friction.

Question 424

Topic: Wrist & Carpus

Which of the following radiographic parameters is generally considered the most important to achieve and maintain for good long-term functional outcomes in a high-demand patient following a distal radius fracture?

. Restoration of radial height
. Preservation of ulnar variance
. Maintenance of volar tilt
. Anatomical reduction of the articular surface (step-off/gap <1mm)
. Absence of associated ulnar styloid fracture

Correct Answer & Explanation

. Anatomical reduction of the articular surface (step-off/gap <1mm)

Explanation

While all listed parameters are important for anatomical reduction, anatomical reduction of the articular surface (minimal or no intra-articular step-off or gap, typically <1-2mm) is universally considered the most critical factor for preventing post-traumatic arthritis and achieving good long-term functional outcomes, particularly in younger, active patients. Articular incongruity directly disrupts the smooth gliding surfaces of the joint, leading to focal high-stress areas and accelerated cartilage degeneration.

Question 425

Topic: Wrist & Carpus

A 60-year-old patient develops symptomatic ulnar positive variance and impaction pain 1 year after non-operative management of a distal radius fracture with 4mm radial shortening. All conservative measures have failed. What is the most appropriate surgical option?

. Radial shortening osteotomy
. Ulnar shortening osteotomy
. DRUJ fusion
. Total wrist fusion
. Excision of the ulnar head (Darrach procedure)

Correct Answer & Explanation

. Ulnar shortening osteotomy

Explanation

Symptomatic ulnar positive variance (the ulna is longer relative to the radius) leading to ulnocarpal impaction pain is a common sequela of distal radius malunion with radial shortening. The most appropriate surgical correction for this, assuming the DRUJ is stable, is an ulnar shortening osteotomy. This procedure restores length balance between the radius and ulna, decompressing the ulnocarpal joint. Radial shortening osteotomy would worsen the problem. DRUJ fusion and total wrist fusion are salvage procedures. Darrach procedure (ulnar head excision) is also a salvage procedure for DRUJ arthritis/instability, not typically for ulnocarpal impaction with a stable DRUJ.

Question 426

Topic: Wrist & Carpus

Which of the following factors is considered the strongest independent predictor of developing post-traumatic arthritis after a distal radius fracture?

. Age > 60 years
. Female gender
. Dorsal tilt > 10 degrees
. Intra-articular step-off > 2mm
. Radial shortening > 3mm

Correct Answer & Explanation

. Intra-articular step-off > 2mm

Explanation

Intra-articular step-off or gap greater than 1-2mm is widely recognized as the strongest independent predictor of post-traumatic arthritis following a distal radius fracture. Articular incongruity directly disrupts the smooth gliding surfaces of the joint, leading to focal high-stress areas and accelerated cartilage degeneration. While other factors contribute to overall outcome, articular step-off directly causes arthritis.

Question 427

Topic: Wrist & Carpus

The Sauve-Kapandji procedure is a surgical option primarily used for the management of:

. Nonunion of the distal radius
. Scapholunate dissociation
. Symptomatic malunion of the distal radius
. Symptomatic arthritis and instability of the distal radioulnar joint (DRUJ)
. Flexor tendon rupture

Correct Answer & Explanation

. Symptomatic arthritis and instability of the distal radioulnar joint (DRUJ)

Explanation

The Sauve-Kapandji procedure involves fusing the distal radioulnar joint (DRUJ) and creating a pseudoarthrosis of the distal ulna proximal to the fusion. This procedure is performed to treat symptomatic DRUJ arthritis and/or instability while preserving forearm rotation. It essentially converts a painful, stiff DRUJ into a stable, painless, albeit pseudoarthrotic, rotational unit.

Question 428

Topic: Wrist & Carpus

Which of the following is often one of the earliest and most commonly overlooked signs/symptoms of developing Complex Regional Pain Syndrome (CRPS) Type I after a distal radius fracture?

. Trophic changes (skin atrophy, hair loss)
. Progressive increase in resting pain out of proportion to injury
. Radiographic osteopenia
. Joint stiffness and contracture
. Profound sweating or dryness of the affected limb

Correct Answer & Explanation

. Progressive increase in resting pain out of proportion to injury

Explanation

The earliest and most consistent symptom of CRPS is typically severe, burning pain that is disproportionate to the inciting injury and persists beyond the expected healing time. This pain often progresses to allodynia and hyperalgesia. Trophic changes, osteopenia, stiffness, and autonomic dysfunction (sweating/dryness) are usually later signs. Early recognition of disproportionate pain is critical for prompt diagnosis and intervention.

Question 429

Topic: Wrist & Carpus

After fixation of a distal radius fracture, a patient continues to have chronic, activity-related ulnar-sided wrist pain. Physical examination suggests a TFCC injury. What is the most definitive imaging modality to confirm the diagnosis and guide further management?

. Plain radiographs
. CT scan
. MRI with arthrogram
. Ultrasound
. Diagnostic wrist arthroscopy

Correct Answer & Explanation

. Diagnostic wrist arthroscopy

Explanation

While MRI with arthrogram can provide excellent detail of the TFCC, the gold standard for definitively diagnosing and characterizing TFCC tears, especially for surgical planning, remains diagnostic wrist arthroscopy. Arthroscopy allows for direct visualization, probing, and dynamic assessment of the TFCC and other intra-articular structures, often leading directly to repair or debridement. Plain radiographs and CT are primarily for bony pathology. Ultrasound has limited utility for deep ligamentous structures like the TFCC.

Question 430

Topic: Wrist & Carpus

In a case of distal radius fracture with a suspected intra-articular extension, which imaging modality provides the most detailed information regarding articular congruity and fragment displacement?

. Standard AP and lateral radiographs
. Oblique radiographs
. CT scan with 3D reconstruction
. MRI
. Ultrasound

Correct Answer & Explanation

. CT scan with 3D reconstruction

Explanation

While plain radiographs (AP, lateral, obliques) are the initial imaging, a CT scan with 3D reconstruction is superior for evaluating the exact configuration of intra-articular comminution, articular step-off, and displacement in distal radius fractures. It provides detailed cross-sectional images, which are crucial for surgical planning. MRI is better for soft tissue injuries (ligaments, TFCC), and ultrasound has limited utility for complex bony fractures.

Question 431

Topic: Wrist & Carpus

In the presence of an unstable DRUJ associated with a distal radius fracture, which component of the TFCC is most commonly implicated in the instability?

. Articular disc
. Meniscal homologue
. Extensor Carpi Ulnaris (ECU) subsheath
. Volar and dorsal radioulnar ligaments
. Ulnar collateral ligament

Correct Answer & Explanation

. Volar and dorsal radioulnar ligaments

Explanation

The volar and dorsal radioulnar ligaments (RULs) are the primary stabilizing components of the TFCC. Tears or avulsions of these ligaments from their radial or ulnar attachments are the most common cause of DRUJ instability associated with distal radius fractures. While the articular disc is part of the TFCC, the RULs are the key static stabilizers preventing excessive translation of the ulna relative to the radius.

Question 432

Topic: Wrist & Carpus

A patient is undergoing rehabilitation after volar plating for a distal radius fracture. They develop localized pain, swelling, and crepitus with active pronation and supination, which worsens with resisted forearm rotation. What is a likely complication?

. Nonunion of the fracture
. EPL tendonitis
. Hardware failure
. Extensor tendon irritation
. DRUJ impingement or instability

Correct Answer & Explanation

. DRUJ impingement or instability

Explanation

Localized pain, swelling, and crepitus with active pronation and supination that worsens with resisted forearm rotation strongly suggest a problem with the distal radioulnar joint (DRUJ). This could be due to post-traumatic DRUJ arthritis, instability (subluxation), or impingement. Nonunion is unlikely given early post-op. EPL tendonitis would involve thumb motion. Hardware failure is possible but usually presents differently. Extensor tendon irritation is more common with dorsal plating.

Question 433

Topic: Wrist & Carpus
Which classification system for distal radius fractures emphasizes the mechanism of injury and helps guide treatment based on fracture pattern (bending, shearing, compression, avulsion, combined)?
. Frykman classification
. AO/OTA classification
. Universal classification
. Fernandez classification
. Gartland classification

Correct Answer & Explanation

. Fernandez classification

Explanation

The Fernandez classification system for distal radius fractures specifically emphasizes the mechanism of injury and helps guide treatment based on the fracture pattern (Type I: bending, Type II: shearing, Type III: compression, Type IV: avulsion, Type V: combined/high-energy). This differentiates it from Frykman (articular involvement + ulnar fracture), AO/OTA (fracture location, articular involvement, and stability), and Universal (combines features but less focus on mechanism). Gartland is for pediatric supracondylar humerus fractures.

Question 434

Topic: Wrist & Carpus

What is the maximum acceptable intra-articular step-off in a distal radius fracture for a younger, active individual to minimize the risk of post-traumatic arthritis?

. 0.5 mm
. 1 mm
. 2 mm
. 3 mm
. 5 mm

Correct Answer & Explanation

. 1 mm

Explanation

For younger, active individuals, the goal is often an anatomical reduction, especially of the articular surface. While some literature accepts up to 2mm, most surgeons aim for less than 1mm of intra-articular step-off or gap to significantly minimize the risk of symptomatic post-traumatic arthritis. A step-off of 0.5mm or less is ideal.

Question 435

Topic: Wrist & Carpus

A distal radius fracture treated non-operatively develops delayed union. What is the most common reason for delayed union in the distal radius?

. Poor patient compliance
. Smoking
. Inadequate nutritional status
. Infection
. Delayed union is more commonly a diagnosis of exclusion in this well-vascularized bone, often associated with patient factors or severe comminution.

Correct Answer & Explanation

. Delayed union is more commonly a diagnosis of exclusion in this well-vascularized bone, often associated with patient factors or severe comminution.

Explanation

The distal radius has an excellent blood supply, making nonunion and even delayed union relatively uncommon compared to other long bones. When delayed union occurs, it is often a diagnosis of exclusion and can be attributed to factors such as severe comminution, inadequate immobilization, high-energy injury, significant soft tissue damage, or patient-specific factors like smoking or uncontrolled diabetes. While infection, poor compliance, and nutrition can contribute, for a well-vascularized bone like the distal radius, a combination of factors or underlying challenges in healing (rather than a single isolated cause like 'poor vascularity') is often implied.

Question 436

Topic: Wrist & Carpus

What is the primary goal of the 'sugar tong' splint in the initial management of a significantly displaced distal radius fracture?

. To allow for early range of motion
. To provide rigid internal fixation
. To provide rotational control and prevent forearm supination/pronation
. To facilitate weight-bearing on the wrist
. To minimize swelling through compression

Correct Answer & Explanation

. To provide rotational control and prevent forearm supination/pronation

Explanation

A sugar tong splint provides excellent immobilization and, critically, rotational control of the forearm. By extending above the elbow, it prevents supination and pronation, which are movements that can disrupt the reduction of a distal radius fracture, especially those with significant displacement or DRUJ involvement. It is a temporary measure, not a definitive fixation, and doesn't allow early motion or facilitate weight-bearing.

Question 437

Topic: Wrist & Carpus

What is the primary role of the interosseous membrane (IOM) in forearm stability?

. To prevent valgus instability of the elbow
. To resist pronation of the forearm
. To transmit axial loads from the radius to the ulna
. To provide attachment for the biceps tendon
. To stabilize the distal radio-ulnar joint (DRUJ) directly

Correct Answer & Explanation

. To transmit axial loads from the radius to the ulna

Explanation

The interosseous membrane (IOM) is crucial for longitudinal forearm stability, particularly in transmitting axial loads from the radius to the ulna. It acts as a primary load-bearing structure between the two bones, especially during activities involving compression through the hand. It doesn't primarily prevent valgus instability (that's MCL's role), resist pronation, or directly stabilize the DRUJ (though its disruption leads to DRUJ issues), nor is it for biceps attachment.

Question 438

Topic: Wrist & Carpus

Which of the following describes the function of the oblique cord?

. Primary stabilizer of the distal radioulnar joint
. Reinforces the anterior capsule of the elbow
. Secondary stabilizer of the forearm resisting proximal migration of the radius
. Maintains the position of the radial head in the lesser sigmoid notch
. Prevents valgus stress at the elbow

Correct Answer & Explanation

. Secondary stabilizer of the forearm resisting proximal migration of the radius

Explanation

The oblique cord is a fibrous band extending from the ulna to the radius, just distal to the radial tuberosity. It is considered a secondary stabilizer of the forearm, providing some resistance to proximal migration of the radius. While not as strong as the interosseous membrane, it contributes to longitudinal stability. It does not primarily stabilize the DRUJ (TFCC does that), reinforce the anterior capsule, maintain radial head position (annular ligament), or prevent valgus stress (MCL/radial head).

Question 439

Topic: Wrist & Carpus
What is the Mayfield classification system primarily used to describe in the context of carpal injuries?
. Severity of Kienböck's disease
. Stages of lunate and perilunate instability
. Types of distal radius fractures
. Grading of triangular fibrocartilage complex (TFCC) tears
. Assessment of ulnar impaction syndrome

Correct Answer & Explanation

. Stages of lunate and perilunate instability

Explanation

The Mayfield classification system describes the progressive stages of perilunate instability and dislocation. It outlines a sequential pattern of ligamentous disruption around the lunate, starting from scapholunate dissociation (Stage I), progressing to capitolunate dislocation (Stage II), triquetrolunate disruption (Stage III), and ultimately lunate dislocation (Stage IV), where the lunate itself displaces volarly. It is not used for Kienböck's disease, distal radius fractures, TFCC tears, or ulnar impaction.

Question 440

Topic: Wrist & Carpus

Which ligament is typically the first to fail in the Mayfield Stage I pattern of perilunate instability?

. Triquetrolunate ligament
. Radioscaphocapitate ligament
. Scapholunate interosseous ligament
. Lunotriquetral interosseous ligament
. Dorsal radiocarpal ligament

Correct Answer & Explanation

. Scapholunate interosseous ligament

Explanation

Mayfield Stage I involves disruption of the scapholunate interosseous ligament (SLIL), leading to scapholunate dissociation. This is the initial step in the progressive arc of perilunate instability. Subsequent stages involve further ligamentous disruptions around the carpus. The other ligaments mentioned become involved in later stages or are not the primary initial failure point in this specific classification system.

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