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Wrist & Carpus MCQs

Practice Set 13 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 241

Topic: Wrist & Carpus
A 50-year-old male presents with chronic wrist pain and a history of remote trauma. Radiographs reveal advanced arthritis of the radioscaphoid and capitolunate joints, with sparing of the radiolunate joint. This radiographic pattern is highly characteristic of which stage of Scapholunate Advanced Collapse (SLAC)?
. Stage I
. Stage II
. Stage III
. Stage IV
. SNAC Stage II

Correct Answer & Explanation

. Stage III

Explanation

SLAC Stage III is characterized by arthritic changes in the radioscaphoid and capitolunate joints. The radiolunate joint is typically spared due to the concentric, purely spherical articulation that does not develop abnormal shear forces.

Question 242

Topic: Wrist & Carpus

A 35-year-old male undergoes ORIF of the radius for a distal-third radial shaft fracture with associated distal radioulnar joint (DRUJ) instability (Galeazzi fracture). Intraoperatively, after anatomic radius fixation, the DRUJ remains grossly irreducible in all forearm positions. What is the most appropriate next step?

. Immobilize the forearm in full pronation
. Percutaneous pinning of the DRUJ
. Open exploration of the DRUJ to remove interposed tissue
. Darrach procedure (distal ulna resection)
. Arthroscopic repair of the triangular fibrocartilage complex (TFCC)

Correct Answer & Explanation

. Open exploration of the DRUJ to remove interposed tissue

Explanation

If the DRUJ remains irreducible after anatomic restoration of the radius in a Galeazzi fracture, open exploration is required. The most common cause is soft tissue interposition, typically the extensor carpi ulnaris (ECU) tendon.

Question 243

Topic: Wrist & Carpus

A 55-year-old female undergoes volar locked plating for a distal radius fracture. Six weeks postoperatively, she suddenly loses the ability to actively extend her thumb interphalangeal joint. What is the most likely iatrogenic cause of this complication?

. Prominent volar plate placement distal to the watershed line
. Dorsal screw penetration into the third extensor compartment
. Intraoperative transection of the posterior interosseous nerve
. Loss of radial height causing attritional wear
. Failure to repair the pronator quadratus

Correct Answer & Explanation

. Dorsal screw penetration into the third extensor compartment

Explanation

Rupture of the extensor pollicis longus (EPL) tendon following volar plating of the distal radius is most frequently caused by prominent screws penetrating the dorsal cortex into the third extensor compartment.

Question 244

Topic: Wrist & Carpus

A 65-year-old female undergoes volar locking plate fixation for a distal radius fracture. Six months later, she is unable to actively flex the interphalangeal joint of her thumb. Which of the following technical errors most likely led to this complication?

. Placement of the plate proximal to the watershed line
. Prominent dorsal screw penetration
. Placement of the plate distal to the watershed line
. Inadequate repair of the pronator quadratus
. Over-drilling of the radial styloid screw

Correct Answer & Explanation

. Placement of the plate distal to the watershed line

Explanation

Flexor pollicis longus (FPL) rupture is a known complication of volar plating. It is most commonly caused by placing the plate at or distal to the watershed line, causing frictional wear on the tendon.

Question 245

Topic: Wrist & Carpus

A 26-year-old construction worker falls off a ladder and sustains a wrist injury. Radiographs reveal a perilunate dislocation. According to Mayfield's stages of perilunate instability, which ligament is injured first?

. Lunotriquetral ligament
. Radioscaphocapitate ligament
. Scapholunate ligament
. Dorsal radiocarpal ligament
. Volar ulnocarpal ligament

Correct Answer & Explanation

. Scapholunate ligament

Explanation

According to Mayfield's stages of progressive perilunate instability, the injury begins radially and progresses ulnarly. Stage I involves disruption of the scapholunate ligament.

Question 246

Topic: Wrist & Carpus

A 60-year-old female presents 6 weeks after a nondisplaced distal radius fracture treated in a short arm cast. She complains of a new inability to actively extend her thumb interphalangeal joint. What is the most appropriate definitive management?

. Primary end-to-end repair of the ruptured tendon
. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer
. Free tendon graft using the palmaris longus
. Corticosteroid injection into the third dorsal compartment
. Extensor carpi radialis longus (ECRL) to EPL tendon transfer

Correct Answer & Explanation

. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer

Explanation

Delayed EPL rupture after a nondisplaced distal radius fracture occurs due to watershed ischemia and mechanical attrition at the Lister tubercle. Primary repair is typically impossible due to tendon degeneration and retraction, making EIP to EPL transfer the gold standard.

Question 247

Topic: Wrist & Carpus

A 32-year-old male sustains a Galeazzi fracture-dislocation. Which of the following factors makes the distal radioulnar joint (DRUJ) most likely to require operative stabilization after anatomic rigid fixation of the radius?

. Fracture location greater than 7.5 cm from the radiocarpal joint
. Fracture location within 7.5 cm of the radiocarpal joint
. Presence of a stable ulnar styloid tip fracture
. Apex volar angulation of the initial radial shaft fracture
. Associated nondisplaced scaphoid fracture

Correct Answer & Explanation

. Fracture location within 7.5 cm of the radiocarpal joint

Explanation

Galeazzi fractures located within 7.5 cm of the radiocarpal articular surface have a significantly higher rate of DRUJ instability following anatomic radial fixation. These injuries frequently require secondary DRUJ pinning or open TFCC repair.

Question 248

Topic: Wrist & Carpus

A 45-year-old male falls from a ladder and presents with a comminuted radial head fracture, severe wrist pain, and positive ulnar variance on radiographs. To prevent progressive longitudinal radioulnar dissociation, which operative step is strictly contraindicated?

. Radial head arthroplasty
. Radial head excision alone
. Pinning of the distal radioulnar joint (DRUJ) in supination
. Repair of the triangular fibrocartilage complex (TFCC)
. Internal fixation of the radial head

Correct Answer & Explanation

. Radial head excision alone

Explanation

This patient has an Essex-Lopresti injury (radial head fracture, interosseous membrane disruption, DRUJ disruption). Excision of the radial head without replacement is strictly contraindicated, as it removes the proximal strut and leads to devastating proximal radial migration.

Question 249

Topic: Wrist & Carpus

A 30-year-old male sustains a Galeazzi fracture-dislocation. After rigid anatomic plate fixation of the radial shaft, the distal radioulnar joint (DRUJ) remains grossly unstable in supination. What is the most appropriate next step in management?

. Cast the arm in pronation for 4 weeks
. Perform a definitive Darrach procedure
. Open reduction of the DRUJ and repair of the triangular fibrocartilage complex (TFCC)
. Resect the ulnar styloid base and allow secondary capsular healing
. Place a spanning external fixator across the radiocarpal joint

Correct Answer & Explanation

. Open reduction of the DRUJ and repair of the triangular fibrocartilage complex (TFCC)

Explanation

If the DRUJ remains unstable after anatomic fixation of the radius in a Galeazzi fracture, especially in supination, it indicates a significant block to reduction or severe soft tissue disruption. Open reduction of the DRUJ with TFCC repair and/or temporary radioulnar pinning is required to restore stability.

Question 250

Topic: Wrist & Carpus

A 22-year-old male sustains an acute proximal pole scaphoid fracture. Operative fixation is planned to minimize the risk of nonunion. Which surgical approach and screw trajectory provide the best biomechanical fixation and biological preservation of the proximal pole?

. Volar percutaneous approach
. Volar open approach with wedge grafting
. Dorsal approach
. Limited intercarpal fusion
. Proximal row carpectomy

Correct Answer & Explanation

. Dorsal approach

Explanation

Proximal pole scaphoid fractures are best treated via a dorsal approach. This preserves the volar blood supply to the scaphoid and allows for a biomechanically superior straight-line screw trajectory down the central axis of the bone.

Question 251

Topic: Wrist & Carpus

A 22-year-old man requires open reduction and internal fixation of a proximal pole scaphoid fracture. Which surgical approach provides the most direct access to the proximal pole while preserving its primary blood supply?

. Volar approach through the FCR sheath
. Dorsal approach
. Volar approach between FCR and radial artery
. Mid-lateral approach
. Volar approach ulnar to the palmaris longus

Correct Answer & Explanation

. Dorsal approach

Explanation

The dorsal approach is preferred for proximal pole scaphoid fractures. It provides direct access to the proximal fragment and avoids injury to the major palmar blood supply, which enters the scaphoid at the distal and middle thirds.

Question 252

Topic: Wrist & Carpus

A 60-year-old woman undergoes volar locked plating for a distal radius fracture. Three months postoperatively, she returns with sudden inability to actively extend her thumb. What is the most likely cause of this complication?

. Rupture of the extensor pollicis longus (EPL) tendon
. Rupture of the flexor pollicis longus (FPL) tendon
. Posterior interosseous nerve (PIN) palsy
. Extensor pollicis brevis (EPB) rupture
. Abductor pollicis longus (APL) rupture

Correct Answer & Explanation

. Rupture of the extensor pollicis longus (EPL) tendon

Explanation

Extensor pollicis longus (EPL) tendon rupture is a known complication of distal radius fractures and volar plating. It often occurs due to prominent dorsal screws penetrating the dorsal cortex and mechanically attriting the tendon in the third extensor compartment.

Question 253

Topic: Wrist & Carpus

A 65-year-old woman undergoes volar plate fixation for a displaced distal radius fracture. Six months later, she presents with an inability to actively flex her thumb interphalangeal joint. What surgical error is most likely responsible for this complication?

. Prominent dorsal screws
. Plate placed proximal to the watershed line
. Plate placed distal to the watershed line
. Over-reduction of volar tilt
. Radial translation of the plate

Correct Answer & Explanation

. Plate placed distal to the watershed line

Explanation

Flexor pollicis longus (FPL) tendon rupture is a known complication of volar plating when the plate is placed too distally (prominent beyond the watershed line), causing mechanical attrition of the tendon.

Question 254

Topic: Wrist & Carpus

A 55-year-old woman underwent volar locked plating of a distal radius fracture 6 months ago. She now presents with a sudden inability to actively flex the interphalangeal joint of her thumb. What is the most likely cause of this complication?

. Extensor pollicis longus rupture
. Flexor carpi radialis rupture
. Flexor pollicis longus rupture
. Flexor digitorum profundus rupture
. Anterior interosseous nerve palsy

Correct Answer & Explanation

. Flexor pollicis longus rupture

Explanation

Flexor pollicis longus (FPL) tendon rupture is a well-documented complication of volar plating for distal radius fractures. It typically occurs due to attritional wear from plate placement distal to the watershed line.

Question 255

Topic: Wrist & Carpus

A 55-year-old woman undergoes volar locked plating for a distal radius fracture. Six months postoperatively, she is unable to actively flex the interphalangeal joint of her thumb. Which of the following technical errors most likely contributed to this complication?

. Placement of screws dorsal to the Lister tubercle
. Plate placement distal to the watershed line
. Inadequate reduction of the volar lunate facet
. Screws penetrating the distal radioulnar joint (DRUJ)
. Failure to repair the pronator quadratus

Correct Answer & Explanation

. Plate placement distal to the watershed line

Explanation

Flexor pollicis longus (FPL) tendon rupture is a known and significant complication of volar locked plating for distal radius fractures. It is most commonly caused by hardware prominence due to plate placement distal to the watershed line, leading to tendon attrition.

Question 256

Topic: Wrist & Carpus

Which of the following represents an acceptable radiographic parameter for the nonoperative management of a distal radius fracture in an active adult?

. Radial shortening of 8 mm
. Articular step-off of 3 mm
. Dorsal tilt less than 10 degrees past neutral
. Radial inclination less than 10 degrees
. Volar tilt greater than 25 degrees

Correct Answer & Explanation

. Radial shortening of 8 mm

Explanation

Acceptable radiographic parameters for nonoperative management of a distal radius fracture typically include radial shortening < 5 mm, dorsal tilt < 10 degrees past neutral (or < 15 degrees), and articular step-off < 2 mm.

Question 257

Topic: Wrist & Carpus

A 28-year-old male sustains a Galeazzi fracture-dislocation. After plate fixation of the radial shaft, the distal radioulnar joint (DRUJ) remains unstable. Which muscle provides the primary deforming force causing volar and ulnar translation of the distal radius fragment?

. Pronator teres
. Pronator quadratus
. Brachioradialis
. Flexor pollicis longus
. Extensor carpi radialis longus

Correct Answer & Explanation

. Pronator quadratus

Explanation

In a Galeazzi fracture, the brachioradialis pulls the proximal fragment proximally, while the pronator quadratus pulls the distal fragment in a volar and ulnar direction, leading to the characteristic deformity.

Question 258

Topic: Wrist & Carpus

A 65-year-old woman undergoes volar plate fixation for a distal radius fracture. Six months postoperatively, she presents with an inability to actively flex the interphalangeal joint of her thumb. Placement of the plate distal to which of the following anatomical landmarks is the primary risk factor for this complication?

. Lister's tubercle
. Watershed line
. Sigmoid notch
. Brachioradialis insertion
. Pronator quadratus insertion

Correct Answer & Explanation

. Watershed line

Explanation

The watershed line is the bony ridge on the volar distal radius. Plate placement distal to this line significantly increases the risk of flexor pollicis longus (FPL) tendon attrition and subsequent rupture.

Question 259

Topic: Wrist & Carpus

During the surgical treatment of a Galeazzi fracture, after plate fixation of the radius, the distal radioulnar joint (DRUJ) is found to be grossly unstable in supination. What is the most appropriate next step?

. Pinning of the DRUJ in supination
. Pinning of the DRUJ in neutral
. Open repair of the triangular fibrocartilage complex (TFCC)
. Ulnar styloid excision
. Casting in pronation

Correct Answer & Explanation

. Pinning of the DRUJ in supination

Explanation

If the DRUJ remains unstable after anatomic radius fixation in a Galeazzi fracture, it should be stabilized. This is commonly achieved by percutaneous K-wire pinning of the ulna to the radius with the forearm in full supination.

Question 260

Topic: Wrist & Carpus

A 65-year-old female undergoes volar locking plate fixation for a displaced distal radius fracture. Four months postoperatively, she suddenly loses the ability to flex the interphalangeal joint of her thumb. Which of the following technical errors most likely contributed to this complication?

. Use of screws that were too long, protruding dorsally
. Placement of the volar plate distal to the watershed line
. Failure to repair the pronator quadratus over the plate
. Over-distraction of the fracture fragment
. Inadequate reduction of the dorsal cortex

Correct Answer & Explanation

. Placement of the volar plate distal to the watershed line

Explanation

Placement of a volar plate distal to the watershed line of the distal radius causes prominence of the hardware against the flexor tendons. This places the flexor pollicis longus (FPL) tendon at high risk for attritional rupture.

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