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7. Hand and Wrist MCQs

Practice Set 122 of 266

This practice set contains high-yield board review questions covering key concepts in 7. Hand and Wrist. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 2421

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 2422

Topic: 7. Hand and Wrist

A 24-year-old male presents 3 weeks after a fall onto an outstretched hand. MRI confirms a non-displaced proximal pole scaphoid fracture. What is the blood supply to the proximal pole of the scaphoid and the optimal management?

. Retrograde blood supply via dorsal carpal branch of radial artery; cast immobilization
. Antegrade blood supply via superficial palmar arch; percutaneous screw fixation
. Retrograde blood supply via dorsal carpal branch of radial artery; percutaneous screw fixation
. Antegrade blood supply via dorsal carpal branch of radial artery; cast immobilization
. Retrograde blood supply via ulnar artery; open reduction and internal fixation

Correct Answer & Explanation

. Retrograde blood supply via dorsal carpal branch of radial artery; percutaneous screw fixation

Explanation

The proximal pole relies on a retrograde blood supply from the dorsal carpal branch of the radial artery, making it prone to avascular necrosis. Due to high nonunion rates and prolonged healing times, screw fixation is generally recommended over casting for proximal pole fractures.

Question 2423

Topic: 7. Hand and Wrist

A 28-year-old male sustains a distal third radial shaft fracture with associated distal radioulnar joint (DRUJ) dislocation. After rigid plate fixation of the radius, the DRUJ remains irreducible. Which of the following structures is most commonly blocking reduction?

. Flexor carpi ulnaris tendon
. Extensor carpi ulnaris tendon
. Median nerve
. Ulnar nerve
. Extensor digitorum communis tendons

Correct Answer & Explanation

. Extensor carpi ulnaris tendon

Explanation

In a Galeazzi fracture-dislocation, if the DRUJ is irreducible following anatomic fixation of the radius, soft tissue interposition should be suspected. The extensor carpi ulnaris (ECU) tendon is the most common structure blocking reduction.

Question 2424

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 2425

Topic: Nerve & Tendon

A 42-year-old male undergoes tension band wiring for a transverse olecranon fracture. Postoperatively, he is unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. What structure was likely injured?

. Median nerve at the ligament of Struthers
. Ulnar nerve at the cubital tunnel
. Anterior interosseous nerve from prominent K-wires
. Posterior interosseous nerve from surgical approach
. Radial nerve at the spiral groove

Correct Answer & Explanation

. Anterior interosseous nerve from prominent K-wires

Explanation

The anterior interosseous nerve (AIN) can be injured by overly long Kirschner wires penetrating the anterior cortex of the ulna during tension band wiring. AIN palsy presents with weakness of the FPL and FDP to the index finger.

Question 2426

Topic: 7. Hand and Wrist

A 22-year-old male sustains a proximal pole scaphoid fracture. The high rate of avascular necrosis associated with this specific injury pattern is primarily due to the retrograde blood supply entering the scaphoid via which of the following vessels?

. Volar carpal branch of the radial artery
. Superficial palmar arch
. Dorsal carpal branch of the radial artery
. Anterior interosseous artery
. Ulnar artery branches

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

The scaphoid receives its primary blood supply in a retrograde fashion from the dorsal carpal branch of the radial artery, which enters at the dorsal ridge. Proximal pole fractures disrupt this precarious intraosseous supply, leading to high rates of AVN.

Question 2427

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 2428

Topic: 7. Hand and Wrist

According to the Mayfield classification of progressive perilunate instability, what structural failure marks the final sequence (Stage IV) of the injury cascade?

. Scapholunate ligament disruption
. Volar dislocation of the lunate into the carpal tunnel
. Dorsal dislocation of the capitate
. Lunotriquetral ligament disruption
. Avulsion of the dorsal radiocarpal ligament

Correct Answer & Explanation

. Volar dislocation of the lunate into the carpal tunnel

Explanation

Mayfield Stage IV represents a complete volar lunate dislocation into the carpal tunnel following disruption of the dorsal radiocarpal ligaments. This represents the terminal event of the progressive perilunate destabilization sequence.

Question 2429

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 2430

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 2431

Topic: 7. Hand and Wrist

In the typical progression of Scapholunate Advanced Collapse (SLAC) wrist, which carpal articulation is characteristically spared from degenerative joint disease?

. Radioscaphoid joint
. Capitolunate joint
. Scaphocapitate joint
. Radiolunate joint
. Triscaphe joint

Correct Answer & Explanation

. Radiolunate joint

Explanation

In SLAC wrist, the radiolunate joint is characteristically spared from osteoarthritis because the lunate fossa is concentric and the lunate cartilage is maintained despite the bone extending into a DISI deformity. The radioscaphoid joint is the first to degenerate.

Question 2432

Topic: 7. Hand and Wrist

A 45-year-old female treated non-operatively for a minimally displaced distal radius fracture presents 6 weeks later with a sudden inability to actively extend her thumb interphalangeal joint. What is the most likely pathophysiologic mechanism for this complication?

. Avascular necrosis of the thumb metacarpal base
. Attritional rupture of the tendon over Lister's tubercle
. Entrapment of the extensor tendon within the fracture site
. Iatrogenic nerve injury from excessive cast compression
. Unrecognized concomitant first carpometacarpal joint dislocation

Correct Answer & Explanation

. Attritional rupture of the tendon over Lister's tubercle

Explanation

Extensor pollicis longus (EPL) tendon rupture is a known complication of nondisplaced or minimally displaced distal radius fractures. It typically occurs due to attritional wear over the intact but roughened bony anatomy at Lister's tubercle, combined with local ischemia in the third dorsal compartment.

Question 2433

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 2434

Topic: 7. Hand and Wrist

A 28-year-old male presents with a swollen, painful wrist after falling from a ladder. Radiographs demonstrate a volar perilunate dislocation. He complains of severe numbness and tingling in his thumb, index, and middle fingers. Which anatomic mechanism is most directly responsible for these neurologic symptoms?

. Direct contusion to the ulnar nerve within Guyon's canal
. Tethering of the radial sensory nerve over the displaced dorsal carpus
. Volar displacement of the lunate compressing the median nerve within the carpal tunnel
. Avulsion of the anterior interosseous nerve at the level of the pronator quadratus
. Acute compartment syndrome of the deep volar forearm

Correct Answer & Explanation

. Volar displacement of the lunate compressing the median nerve within the carpal tunnel

Explanation

Perilunate and lunate dislocations frequently cause acute carpal tunnel syndrome because the lunate rotates and displaces volarly directly into the carpal tunnel. This causes acute mechanical compression of the median nerve, necessitating urgent reduction.

Question 2435

Topic: 7. Hand and Wrist

A 65-year-old active female sustains a distal radius fracture after a fall on an outstretched hand. Which of the following initial radiographic parameters is the most reliable predictor that nonoperative management in a cast will fail and result in unacceptable deformity?

. Initial radial shortening of 2 mm
. Initial dorsal angulation greater than 20 degrees
. Volar comminution without dorsal involvement
. An associated ulnar styloid base fracture
. Intra-articular step-off of 1 mm

Correct Answer & Explanation

. Initial dorsal angulation greater than 20 degrees

Explanation

Initial dorsal angulation greater than 20 degrees, along with dorsal comminution and older age, is a strong predictor of late displacement in distal radius fractures treated nonoperatively.

Question 2436

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 2437

Topic: Nerve & Tendon

An 18-year-old male sustains a complete distal biceps tendon rupture. He undergoes repair via a single-incision anterior approach. Which of the following nerves is most at risk of injury with this specific surgical approach?

. Radial nerve
. Posterior interosseous nerve
. Lateral antebrachial cutaneous nerve
. Median nerve
. Ulnar nerve

Correct Answer & Explanation

. Lateral antebrachial cutaneous nerve

Explanation

The lateral antebrachial cutaneous nerve (LABC) is the most commonly injured nerve during a single-incision distal biceps repair. The posterior interosseous nerve is more commonly injured with the two-incision technique.

Question 2438

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 2439

Topic: 7. Hand and Wrist
A 45-year-old manual laborer presents with progressive wrist pain and a history of remote trauma. Radiographs demonstrate degenerative changes between the radial styloid and the scaphoid, as well as between the scaphoid and the entire scaphoid fossa of the radius. The radiolunate joint is spared. What is the correct SLAC wrist stage?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage II

Explanation

Scapholunate Advanced Collapse (SLAC) Stage II is characterized by osteoarthritis progressing to involve the entire radioscaphoid articulation. Stage I involves only the radial styloid, while Stage III progresses to the capitolunate joint.

Question 2440

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.

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