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Wrist & Carpus MCQs

Practice Set 27 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 521

Topic: Wrist & Carpus

The Triangular Fibrocartilage Complex (TFCC) is the primary stabilizer of the distal radioulnar joint (DRUJ). Which specific component of the TFCC is the primary restraint to dorsal and volar translation of the radius relative to the ulna?

. Articular disc
. Meniscus homologue
. Volar and dorsal radioulnar ligaments
. Ulnocollateral ligament
. Extensor carpi ulnaris subsheath

Correct Answer & Explanation

. Articular disc

Explanation

The volar and dorsal radioulnar ligaments form the thickened margins of the articular disc of the TFCC. They are the primary stabilizers of the DRUJ, preventing dorsal and volar translation of the radius over the fixed ulna during pronation and supination.

Question 522

Topic: Wrist & Carpus

The central band of the forearm interosseous membrane is critical for longitudinal stability of the radioulnar relationship. What is the predominant fiber orientation of this central band?

. Originates on the radius and runs distally and ulnarly to insert on the ulna
. Originates on the ulna and runs distally and radially to insert on the radius
. Runs purely transversely between the radius and ulna
. Originates on the radial tuberosity and runs proximally to the coronoid
. Interdigitates equally in a cross-hatched pattern

Correct Answer & Explanation

. Originates on the radius and runs distally and ulnarly to insert on the ulna

Explanation

The fibers of the central band of the interosseous membrane originate on the radius and course distally and obliquely (ulnarly) to insert on the ulna. This orientation is biomechanically suited to transmit axial loads applied to the distal radius proximally towards the ulna.

Question 523

Topic: Wrist & Carpus

Extensor pollicis longus (EPL) tendon ruptures can occur following distal radius fractures. The EPL tendon typically passes around a bony prominence on the dorsal radius. This prominence acts as a pulley and separates which two extensor compartments?

. Compartments 1 and 2
. Compartments 2 and 3
. Compartments 3 and 4
. Compartments 4 and 5
. Compartments 5 and 6

Correct Answer & Explanation

. Compartments 1 and 2

Explanation

Lister's tubercle is a bony prominence on the dorsal distal radius. It separates the second extensor compartment (ECRL, ECRB) from the third extensor compartment (EPL), which uses the tubercle as a mechanical pulley.

Question 524

Topic: Wrist & Carpus

Six months after undergoing volar locked plating for a displaced distal radius fracture, a 55-year-old female reports a sudden inability to actively flex the interphalangeal joint of her thumb. Which of the following is the most likely cause of this complication?

. Rupture of the flexor pollicis longus tendon
. Rupture of the extensor pollicis longus tendon
. Anterior interosseous nerve palsy
. Adhesions of the flexor digitorum profundus
. Failure of the volar locking plate

Correct Answer & Explanation

. Rupture of the flexor pollicis longus tendon

Explanation

Prominence of the plate distal to the watershed line on the volar radius can cause attrition and subsequent rupture of the flexor pollicis longus (FPL) tendon. This is a well-documented complication of volar locked plating.

Question 525

Topic: Wrist & Carpus

A 60-year-old female undergoes volar locking plate fixation for a displaced distal radius fracture. Six months postoperatively, she presents with an inability to actively flex the interphalangeal joint of her thumb. What is the most likely cause?

. Extensor pollicis longus (EPL) rupture from dorsal screw prominence
. Flexor pollicis longus (FPL) rupture from plate placement distal to the watershed line
. Anterior interosseous nerve (AIN) neuropraxia
. Adhesions of the flexor digitorum profundus (FDP)
. Failure of the fracture fixation

Correct Answer & Explanation

. Extensor pollicis longus (EPL) rupture from dorsal screw prominence

Explanation

Placement of a volar plate distal to the watershed line increases the risk of flexor tendon irritation and rupture. The Flexor Pollicis Longus (FPL) is the most commonly ruptured tendon due to its anatomical proximity to the prominent distal edge of the plate.

Question 526

Topic: Wrist & Carpus

A 65-year-old female presents with an inability to flex her thumb interphalangeal joint six months after undergoing volar plate fixation for a distal radius fracture. Radiographs indicate the plate is positioned distally, bridging the watershed line. Which of the following tendons is most likely ruptured?

. Flexor digitorum superficialis to the index finger
. Flexor carpi radialis
. Flexor pollicis longus
. Extensor pollicis longus
. Abductor pollicis longus

Correct Answer & Explanation

. Flexor digitorum superficialis to the index finger

Explanation

Placement of a volar plate distal to the watershed line of the distal radius increases the risk of flexor tendon irritation and rupture. The flexor pollicis longus (FPL) is the most frequently ruptured tendon in this scenario.

Question 527

Topic: Wrist & Carpus

A 62-year-old woman is treated in a short arm cast for a minimally displaced, extra-articular fracture of the distal radius. Four weeks later, her cast is removed, but she suddenly loses the ability to actively extend her thumb interphalangeal joint. She has no sensory deficits. What is the most likely etiology of this complication?

. Iatrogenic injury to the radial nerve from cast compression
. Avascular necrosis of the scaphoid leading to mechanical block
. Attritional rupture of the extensor pollicis longus (EPL) tendon
. Compression of the posterior interosseous nerve (PIN) by fracture callus
. Unrecognized associated radiocarpal dislocation

Correct Answer & Explanation

. Iatrogenic injury to the radial nerve from cast compression

Explanation

EPL tendon rupture is a well-documented complication following nondisplaced or minimally displaced distal radius fractures treated conservatively. It occurs due to localized ischemia within the third dorsal compartment (a watershed area for the tendon as it angles around Lister's tubercle), compounded by mechanical attrition from the fracture hematoma or callus.

Question 528

Topic: Wrist & Carpus
A 45-year-old manual laborer presents with progressive wrist pain following an untreated scaphoid fracture 5 years ago. Radiographs demonstrate a scaphoid non-union advanced collapse (SNAC) pattern. Degenerative changes are noted at the radial styloid and the entire radioscaphoid joint, but the capitolunate and radiolunate joints are preserved. What is the correct SNAC stage for this patient?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage II

Explanation

The SNAC (Scaphoid Nonunion Advanced Collapse) classification outlines the progression of arthritis. Stage I: Arthritis localized to the radial styloid. Stage II: Arthritis extending to involve the entire radioscaphoid joint. Stage III: Arthritis progresses to involve the capitolunate joint. Stage IV: Pancarpal arthritis (though the radiolunate joint is often remarkably spared until very late). Because the entire radioscaphoid joint is involved but the capitolunate is spared, this is Stage II.

Question 529

Topic: Wrist & Carpus

A patient undergoes volar plating for a distal radius fracture. Postoperatively, the patient develops an attrition rupture of the flexor pollicis longus (FPL) tendon. This complication is most commonly associated with plate placement distal to which anatomical landmark?

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

Correct Answer & Explanation

. Pronator quadratus insertion

Explanation

Placing a volar locking plate distal to the watershed line of the distal radius causes prominence of the hardware against the volar flexor tendons. This leads to friction, tenosynovitis, and potential attrition rupture of the flexor pollicis longus (FPL) tendon.

Question 530

Topic: Wrist & Carpus

A 28-year-old gymnast presents with ulnar-sided wrist pain and clicking after a fall. Examination reveals a positive fovea sign. Arthroscopy confirms a traumatic avulsion of the Triangular Fibrocartilage Complex (TFCC) from its insertion at the fovea of the ulnar head. According to the Palmer classification, what type of TFCC tear is this?

. Class 1A
. Class 1B
. Class 1C
. Class 1D
. Class 2A

Correct Answer & Explanation

. Class 1A

Explanation

The Palmer classification divides TFCC tears into traumatic (Class 1) and degenerative (Class 2). Class 1A is a central perforation (avascular zone, typically debrided). Class 1B is an ulnar avulsion (from the ulnar styloid or fovea, highly vascular, amenable to repair). Class 1C is a distal avulsion involving the ulnocarpal ligaments. Class 1D is a radial avulsion (from the sigmoid notch of the radius). Class 2 tears involve degenerative wear.

Question 531

Topic: Wrist & Carpus
According to the Mayfield classification of perilunate instability, what is the anatomic sequence of ligamentous disruption around the lunate as the severity of injury progresses from Stage I to Stage IV?
. Scapholunate -> Lunotriquetral -> Capitolunate -> Dorsal radiocarpal
. Scapholunate -> Capitolunate -> Lunotriquetral -> Dorsal radiocarpal
. Lunotriquetral -> Capitolunate -> Scapholunate -> Dorsal radiocarpal
. Capitolunate -> Scapholunate -> Lunotriquetral -> Volar radiocarpal
. Dorsal radiocarpal -> Scapholunate -> Capitolunate -> Lunotriquetral

Correct Answer & Explanation

. Scapholunate -> Capitolunate -> Lunotriquetral -> Dorsal radiocarpal

Explanation

The Mayfield progression of perilunate instability occurs in a specific sequence around the lunate: Stage I (Scapholunate ligament disruption), Stage II (Capitolunate joint disruption/dislocation), Stage III (Lunotriquetral ligament disruption), and Stage IV (Lunate dislocation, failing the dorsal radiocarpal ligament and extruding the lunate volarly).

Question 532

Topic: Wrist & Carpus

A 45-year-old female sustains a volar Barton's fracture of the distal radius. This fracture pattern involves a volar marginal articular fragment that subluxates with the carpus. Which critical radiocarpal ligament complex remains attached to this volar fragment, mediating the volar subluxation of the carpus?

. Dorsal radiocarpal ligament
. Scapholunate interosseous ligament
. Volar radiolunate ligaments (short and long)
. Triangular fibrocartilage complex (TFCC)
. Ulnocarpal ligaments

Correct Answer & Explanation

. Dorsal radiocarpal ligament

Explanation

A volar Barton's fracture is a shear fracture of the volar rim of the distal radius (typically involving the volar lunate facet). The volar radiolunate ligaments (short and long) remain attached to this fragment, and because the carpus remains tethered to this fragment via these ligaments, the entire carpus subluxates volarly with the fractured rim.

Question 533

Topic: Wrist & Carpus

A 32-year-old male sustains a Galeazzi fracture-dislocation. Following rigid internal fixation of the radius, the distal radioulnar joint (DRUJ) is evaluated and found to be unstable in all positions of forearm rotation. What is the most appropriate next step in management?

. Open exploration and repair of the TFCC or percutaneous pinning of the DRUJ in a reduced position
. Cast immobilization in full supination for 6 weeks
. Immediate resection of the distal ulna (Darrach procedure)
. Dynamic splinting of the wrist and forearm
. Ulnar shortening osteotomy

Correct Answer & Explanation

. Open exploration and repair of the TFCC or percutaneous pinning of the DRUJ in a reduced position

Explanation

If the DRUJ remains grossly unstable in all planes after rigid radial fixation in a Galeazzi fracture, the joint must be stabilized via percutaneous transfixation pins or open TFCC repair.

Question 534

Topic: Wrist & Carpus

A 60-year-old female presents with a comminuted distal radius fracture and undergoes volar locked plating. During screw placement in the most distal row, the surgeon must be careful to avoid dorsal cortex penetration to prevent tendon rupture in which dorsal extensor compartment?

. First dorsal compartment
. Second dorsal compartment
. Third dorsal compartment
. Fourth dorsal compartment
. Sixth dorsal compartment

Correct Answer & Explanation

. First dorsal compartment

Explanation

Dorsal screw prominence past the distal radius cortex frequently irritates or ruptures the extensor pollicis longus (EPL) tendon, which resides in the third dorsal compartment.

Question 535

Topic: Wrist & Carpus

Six weeks after being treated non-operatively for a non-displaced distal radius fracture, a 68-year-old woman presents with a sudden inability to actively extend her thumb interphalangeal (IP) joint. Which tendon transfer is the most appropriate definitive management?

. Extensor indicis proprius (EIP) to Extensor pollicis longus (EPL)
. Extensor carpi radialis brevis (ECRB) to EPL
. Flexor digitorum superficialis (FDS) to EPL
. Palmaris longus (PL) to EPL
. Brachioradialis (BR) to EPL

Correct Answer & Explanation

. Extensor indicis proprius (EIP) to Extensor pollicis longus (EPL)

Explanation

Spontaneous rupture of the EPL tendon is a known complication of non-displaced distal radius fractures. The EIP to EPL tendon transfer is the gold standard treatment to restore thumb IP extension.

Question 536

Topic: Wrist & Carpus

A surgeon plans to perform a 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) vascularized bone graft for a scaphoid proximal pole nonunion. The pedicle for this graft is derived from which of the following source vessels?

. Anterior interosseous artery
. Radial artery
. Ulnar artery
. Posterior interosseous artery
. Deep palmar arch

Correct Answer & Explanation

. Anterior interosseous artery

Explanation

The 1,2 ICSRA is a consistently present branch of the radial artery. It courses distally on the dorsal aspect of the distal radius between the first and second extensor compartments and is utilized for pedicled vascularized bone grafts to the scaphoid (Zaidemberg's graft).

Question 537

Topic: Wrist & Carpus

When distinguishing between Scapholunate Advanced Collapse (SLAC) and Scaphoid Nonunion Advanced Collapse (SNAC), which of the following radiographic findings is uniquely characteristic of SNAC?

. Arthrosis of the radiolunate joint
. Sparing of the radiolunate joint
. Normal scapholunate interval
. Proximal migration of the capitate
. Arthrosis of the radioscaphoid joint

Correct Answer & Explanation

. Arthrosis of the radiolunate joint

Explanation

Both SLAC and SNAC predictably spare the radiolunate joint (until end-stage pancarpal arthritis) and both feature progressive radioscaphoid and midcarpal arthritis. However, in SNAC, the scapholunate ligament remains intact, tethering the proximal scaphoid fragment to the lunate; thus, the scapholunate interval remains normal. In SLAC, this ligament is torn, causing a widened SL interval (Terry Thomas sign).

Question 538

Topic: Wrist & Carpus

A 25-year-old male sustains a proximal pole scaphoid fracture. After 6 months of conservative management, he has an established nonunion. MRI with gadolinium demonstrates no enhancement of the proximal pole fragment. What is the most appropriate surgical intervention to optimize the chance of union?

. Percutaneous retrograde headless compression screw
. Volar approach with non-vascularized iliac crest bone graft
. Proximal row carpectomy
. Vascularized bone graft (e.g., free MFC or pedicled)
. Scaphoid excision and 4-corner fusion

Correct Answer & Explanation

. Percutaneous retrograde headless compression screw

Explanation

Lack of gadolinium enhancement on MRI indicates avascular necrosis (AVN) of the proximal pole. In a young patient without advanced arthrosis (SNAC), attempting joint preservation is paramount. A vascularized bone graft (pedicled from the radius or a free medial femoral condyle graft) provides the highest union rates for scaphoid nonunions complicated by severe ischemia or AVN.

Question 539

Topic: Wrist & Carpus
A 35-year-old male presents with wrist pain 8 years after a scaphoid fracture. Radiographs show radioscaphoid and capitolunate arthritis, but the radiolunate and lunotriquetral joints are spared. The diagnosis is SNAC Stage III. What is the most appropriate motion-preserving procedure?
. Radial styloidectomy
. Proximal row carpectomy (PRC)
. Scaphoid excision and four-corner fusion
. Total wrist arthroplasty
. Scaphoid open reduction and internal fixation with iliac crest bone graft

Correct Answer & Explanation

. Scaphoid excision and four-corner fusion

Explanation

SNAC III involves radioscaphoid and capitolunate arthritis. Proximal row carpectomy is contraindicated due to capitolunate degeneration; therefore, scaphoid excision and four-corner fusion is the preferred motion-preserving treatment.

Question 540

Topic: Wrist & Carpus

In the progression of Scaphoid Nonunion Advanced Collapse (SNAC), which of the following joints is typically the last to be involved or remains definitively spared compared to SLAC arthritis?

. Radioscaphoid joint
. Capitolunate joint
. Radiolunate joint
. Scaphotrapezial joint
. Scaphocapitate joint

Correct Answer & Explanation

. Radioscaphoid joint

Explanation

In both SLAC and SNAC wrists, the radiolunate joint is characteristically spared due to the congruent spherical articulation and absence of abnormal shear forces. Arthritis progresses through the radioscaphoid and midcarpal joints before ever affecting the radiolunate joint in end-stage disease.

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