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Wrist & Carpus MCQs

Practice Set 12 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 221

Topic: Wrist & Carpus

A 30-year-old laborer is diagnosed with a Scaphoid Nonunion Advanced Collapse (SNAC) wrist following an unrecognized scaphoid fracture five years prior. As the degenerative cascade of SNAC progresses through its predictable stages, which of the following joints is characteristically the LAST to develop arthritic changes?

. Radioscaphoid joint
. Scaphocapitate joint
. Capitolunate joint
. Lunotriquetral joint
. Radiolunate joint

Correct Answer & Explanation

. Radiolunate joint

Explanation

In both SLAC and SNAC wrist deformities, the radiolunate joint is characteristically spared from degenerative changes until the absolute end stages of the disease. This is because the lunate is concentrically congruent within the spherical lunate fossa of the radius, preserving normal load distribution and protecting the cartilage.

Question 222

Topic: Wrist & Carpus

In Scaphoid Nonunion Advanced Collapse (SNAC) of the wrist, which articulation is characteristically spared from degenerative changes, allowing for motion-preserving salvage procedures such as a four-corner fusion?

. Radioscaphoid joint
. Capitolunate joint
. Radiolunate joint
. Scaphotrapezial joint
. Capitohamate joint

Correct Answer & Explanation

. Radiolunate joint

Explanation

In both SNAC and SLAC (Scapholunate Advanced Collapse) wrist arthritis patterns, the radiolunate joint is characteristically spared from osteoarthritis. This occurs because the lunate maintains a congruent and concentric articulation with the lunate fossa of the radius. This preservation allows for salvage procedures like a four-corner fusion or proximal row carpectomy.

Question 223

Topic: Wrist & Carpus

Six months after open reduction and internal fixation of a distal radius fracture with a volar locking plate, the patient develops a sudden inability to actively extend the interphalangeal joint of the thumb. Which tendon is most likely injured, and what is the primary mechanism?

. Extensor pollicis longus (EPL); attritional rupture due to prominent dorsal screws
. Extensor pollicis brevis (EPB); impingement from the volar plate
. Flexor pollicis longus (FPL); attritional rupture over the watershed line
. Extensor carpi radialis longus (ECRL); iatrogenic transection during surgery
. Extensor pollicis longus (EPL); spontaneous rupture secondary to a previously non-displaced Lister's tubercle fracture

Correct Answer & Explanation

. Extensor pollicis longus (EPL); attritional rupture due to prominent dorsal screws

Explanation

The inability to actively extend the thumb interphalangeal joint indicates a rupture of the Extensor pollicis longus (EPL) tendon. In the setting of a previously placed volar plate, this complication is classically caused by excessively long screws protruding through the dorsal cortex, leading to attritional wear and eventual rupture of the EPL tendon.

Question 224

Topic: Wrist & Carpus

A 24-year-old gymnast presents with ulnar-sided wrist pain. Examination reveals a positive ballottement test (Reagan test). Radiographs show a volar flexed scaphoid and lunate with a dorsally extended triquetrum. What is the most likely diagnosis?

. Scapholunate dissociation (DISI)
. Lunotriquetral dissociation (VISI)
. Midcarpal instability
. Triangular fibrocartilage complex (TFCC) tear
. Perilunate dislocation

Correct Answer & Explanation

. Lunotriquetral dissociation (VISI)

Explanation

Lunotriquetral (LT) ligament tears lead to Volar Intercalated Segment Instability (VISI). The lunate flexes with the scaphoid while the triquetrum extends. The Reagan test (LT ballottement) is positive. Scapholunate tears lead to DISI (Dorsal Intercalated Segment Instability).

Question 225

Topic: Wrist & Carpus

In a patient with negative ulnar variance, which of the following best describes the altered biomechanics across the radiocarpal joint that predisposes the patient to Kienbock's disease?

. Increased load transmission across the radioscaphoid fossa.
. Decreased load transmission through the triangular fibrocartilage complex, resulting in lunate overload on the radius.
. Increased volar intercalated segment instability (VISI) leading to shear stress.
. Decreased vascularity of the palmar intercarpal ligaments.
. Ulnocarpal abutment causing secondary lunate necrosis.

Correct Answer & Explanation

. Decreased load transmission through the triangular fibrocartilage complex, resulting in lunate overload on the radius.

Explanation

Negative ulnar variance decreases the normal load borne by the ulnocarpal joint and triangular fibrocartilage complex (which is normally about 20%). This disproportionately increases the compressive forces transmitted from the distal radius to the lunate, leading to mechanical overload, microtrauma, and predisposing the lunate to avascular necrosis (Kienbock's disease).

Question 226

Topic: Wrist & Carpus

A 45-year-old construction worker presents with chronic wrist pain. Radiographs reveal a scaphoid nonunion advanced collapse (SNAC). Which of the following findings is an absolute contraindication to performing a proximal row carpectomy (PRC)?

. Scapholunate advanced collapse (SLAC) Stage II
. Capitate proximal pole degenerative changes
. Scaphoid nonunion advanced collapse (SNAC) Stage I
. Isolated radioscaphoid arthritis
. Dorsal intercalated segment instability (DISI) without arthritis

Correct Answer & Explanation

. Capitate proximal pole degenerative changes

Explanation

Proximal row carpectomy (PRC) relies on creating a new articulation between the lunate fossa of the distal radius and the proximal pole of the capitate. Therefore, any pre-existing degenerative changes or arthritis at the proximal pole of the capitate (or the lunate fossa) are an absolute contraindication to PRC. In such cases, a four-corner fusion (which relies on an intact radiolunate joint) is typically the preferred salvage procedure.

Question 227

Topic: Wrist & Carpus
A 50-year-old manual laborer complains of chronic wrist pain. Radiographs demonstrate advanced joint space narrowing between the radius and the scaphoid, as well as narrowing between the capitate and the lunate. The radiolunate joint space is perfectly preserved. This radiographic appearance is pathognomonic for 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 wrist progresses in a predictable pattern. Stage I involves the radial styloid and scaphoid. Stage II involves the entire radioscaphoid fossa. Stage III involves proximal migration of the capitate with capitolunate arthritis. The radiolunate joint is characteristically spared due to the concentric shape of the articulation, even in Stage III. Stage IV (controversial) implies pancarpal arthritis including the radiolunate joint.

Question 228

Topic: Wrist & Carpus

A 65-year-old female undergoes open reduction and internal fixation of a distal radius fracture using a volar locking plate. Six months postoperatively, she suddenly loses the ability to actively extend her thumb interphalangeal joint. What is the most likely cause?

. Extensor digitorum communis attrition
. Extensor pollicis longus rupture due to dorsal screw prominence
. Flexor pollicis longus rupture from the volar plate
. Abductor pollicis longus adherence
. Posterior interosseous nerve palsy

Correct Answer & Explanation

. Extensor pollicis longus rupture due to dorsal screw prominence

Explanation

Loss of active thumb IP extension is the hallmark of Extensor Pollicis Longus (EPL) rupture. When a volar locking plate is used, screws that are too long and penetrate the dorsal cortex (especially near Lister's tubercle) can cause attrition and secondary rupture of the EPL tendon.

Question 229

Topic: Wrist & Carpus
Scaphoid Nonunion Advanced Collapse (SNAC) wrist follows a predictable pattern of progressive articular degeneration. Stage III of the SNAC wrist natural history is characterized by degenerative changes specifically involving which of the following articulations?
. Radioscaphoid articulation only
. Scaphocapitate joint
. Capitolunate joint
. Radiolunate joint
. Distal radioulnar joint

Correct Answer & Explanation

. Radiolunate joint

Explanation

SNAC wrist progression occurs as follows: Stage I involves the radial styloid and distal scaphoid fragment. Stage II progresses to involve the radioscaphoid joint and the scaphocapitate joint. Stage III involves the capitolunate joint as the capitate subluxates dorsally. Notably, the radiolunate joint is typically spared in both SNAC and SLAC (Scapholunate Advanced Collapse) patterns due to the congruent nature of the spherical lunate facet.

Question 230

Topic: Wrist & Carpus
A 48-year-old manual laborer presents with chronic wrist pain years after an untreated scapholunate ligament tear. Radiographs show joint space narrowing extending across the entire radioscaphoid articulation. The capitolunate and radiolunate joints appear completely preserved. What is the correct staging for this condition?
. SLAC Stage I
. SLAC Stage II
. SLAC Stage III
. SNAC Stage II
. SNAC Stage III

Correct Answer & Explanation

. SLAC Stage III

Explanation

Scapholunate Advanced Collapse (SLAC) occurs in predictable stages. Stage I involves arthrosis restricted to the radial styloid and scaphoid. Stage II involves the entire radioscaphoid joint. Stage III involves the capitolunate joint. The radiolunate joint is characteristically spared due to its concentric, spherical articulation.

Question 231

Topic: Wrist & Carpus

Three months after open reduction and internal fixation of a distal radius fracture with a volar locking plate, a patient develops a sudden inability to extend the interphalangeal joint of the thumb. What is the most common iatrogenic cause of this specific complication in the setting of volar plating?

. Excessive traction during reduction
. Ischemia from the surgical approach
. Prominent dorsal screws penetrating the dorsal cortex
. Direct intraoperative laceration of the tendon
. Attritional rupture over the distal edge of the volar plate

Correct Answer & Explanation

. Prominent dorsal screws penetrating the dorsal cortex

Explanation

Rupture of the extensor pollicis longus (EPL) tendon after volar plating of the distal radius is most commonly caused by dorsal screw prominence. Screws that are too long penetrate the dorsal cortex and cause mechanical attrition of the EPL tendon within the third extensor compartment. Attrition over the distal edge of the volar plate affects flexor tendons (like the FPL).

Question 232

Topic: Wrist & Carpus

Six weeks after undergoing closed reduction and cast application for a nondisplaced distal radius fracture, a 55-year-old woman suddenly loses the ability to actively extend her thumb at the interphalangeal joint. She denies any new trauma. What is the most appropriate definitive management?

. Observation and dynamic extension splinting for 6 weeks
. Primary end-to-end repair of the ruptured tendon
. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer
. Extensor carpi radialis longus (ECRL) to EPL tendon transfer
. Palmaris longus to EPL tendon transfer

Correct Answer & Explanation

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

Explanation

This patient has sustained a delayed spontaneous rupture of the extensor pollicis longus (EPL) tendon, a well-known complication of nondisplaced or minimally displaced distal radius fractures. Primary end-to-end repair is generally not feasible because the tendon ends rapidly retract and the involved tendon is structurally attenuated or necrotic over Lister's tubercle. The gold standard treatment is a tendon transfer utilizing the extensor indicis proprius (EIP) to the EPL, which restores thumb extension with excellent functional outcomes.

Question 233

Topic: Wrist & Carpus

A 65-year-old woman is seen in the outpatient clinic 6 weeks after sustaining a non-displaced distal radius fracture treated with a short arm cast. She now complains of a sudden inability to actively extend the interphalangeal joint of her thumb. She denies any new trauma. What is the most appropriate definitive surgical management for her condition?

. Primary end-to-end repair of the extensor pollicis longus (EPL) tendon
. Extensor indicis proprius (EIP) to EPL tendon transfer
. Extensor carpi radialis longus (ECRL) to EPL tendon transfer
. Splinting the thumb in extension for 6 weeks
. Thumb interphalangeal joint arthrodesis

Correct Answer & Explanation

. Extensor indicis proprius (EIP) to EPL tendon transfer

Explanation

This patient has suffered a spontaneous rupture of the extensor pollicis longus (EPL) tendon. This is a known complication following distal radius fractures, notably non-displaced fractures. The rupture is usually due to ischemia or mechanical attrition within the third dorsal compartment. Because the tendon ends are often retracted and degenerated, primary end-to-end repair is rarely possible. The standard of care is a tendon transfer utilizing the extensor indicis proprius (EIP) to the EPL.

Question 234

Topic: Wrist & Carpus

A 55-year-old woman presents with the inability to flex the interphalangeal joint of her thumb 6 months after undergoing open reduction and internal fixation of a distal radius fracture. Radiographs show a healed fracture, but the volar locking plate is positioned distal to the watershed line of the radius. Which of the following tendons is most likely injured?

. Flexor carpi radialis
. Flexor pollicis longus
. Flexor digitorum profundus to the index finger
. Extensor pollicis longus
. Extensor indicis proprius

Correct Answer & Explanation

. Flexor pollicis longus

Explanation

Placement of a volar locking plate distal to the watershed line of the distal radius places the flexor tendons at significant risk for attrition and spontaneous rupture. The flexor pollicis longus (FPL) tendon is the most commonly injured tendon in this scenario due to its direct proximity to the prominent hardware on the volar surface.

Question 235

Topic: Wrist & Carpus

A 55-year-old woman is evaluated 4 months after undergoing open reduction and internal fixation of a distal radius fracture with a volar locking plate. She complains of new-onset inability to actively flex the interphalangeal (IP) joint of her thumb. Radiographs reveal the volar plate is positioned distal to the watershed line. What is the most likely cause of her symptom?

. Flexor carpi radialis (FCR) rupture
. Flexor pollicis longus (FPL) tendon rupture
. Extensor pollicis longus (EPL) tendon rupture
. Flexor digitorum profundus (FDP) tendon rupture
. Anterior interosseous nerve (AIN) palsy

Correct Answer & Explanation

. Flexor pollicis longus (FPL) tendon rupture

Explanation

Placement of a volar plate distal to the watershed line of the distal radius increases the risk of flexor tendon attrition and rupture. The flexor pollicis longus (FPL) tendon is at the highest risk due to its anatomical proximity to the plate on the volar surface. EPL ruptures are typically associated with prominent dorsal screws or unreduced dorsal cortical fragments, not volar prominence.

Question 236

Topic: Wrist & Carpus

A 55-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. Which of the following technical errors most likely contributed to this complication?

. Placement of the plate proximal to the watershed line
. Placement of the plate distal to the watershed line
. Use of excessively long dorsal cortical screws
. Failure to release the brachioradialis tendon
. Over-reduction of the volar tilt

Correct Answer & Explanation

. Placement of the plate distal to the watershed line

Explanation

Placement of a volar plate distal to the watershed line of the distal radius risks hardware prominence against the flexor pollicis longus (FPL) tendon. This constant friction can lead to delayed FPL rupture.

Question 237

Topic: Wrist & Carpus
In the natural history of Scapholunate Advanced Collapse (SLAC), Stage III arthritic changes classically involve which of the following articulations?
. Radioscaphoid joint
. Radiolunate joint
. Capitolunate joint
. Scaphotrapezial joint
. Distal radioulnar joint

Correct Answer & Explanation

. Radiolunate joint

Explanation

SLAC progresses in predictable stages: Stage I involves the radial styloid, Stage II encompasses the entire radioscaphoid joint, and Stage III progresses to the capitolunate joint. The radiolunate joint is characteristically spared due to the concentric shape of the lunate fossa.

Question 238

Topic: Wrist & Carpus

A 24-year-old male presents with a proximal pole scaphoid fracture. You elect to proceed with percutaneous screw fixation. Which surgical approach and screw trajectory offer the best mechanical advantage and easiest access for a proximal pole fracture?

. Volar approach, distal to proximal trajectory
. Dorsal approach, proximal to distal trajectory
. Volar approach, proximal to distal trajectory
. Dorsal approach, distal to proximal trajectory
. Radial snuffbox approach, central trajectory

Correct Answer & Explanation

. Dorsal approach, proximal to distal trajectory

Explanation

Proximal pole scaphoid fractures are best approached dorsally to allow a proximal-to-distal screw trajectory. This approach minimizes damage to the precarious blood supply entering distally and allows central placement of the screw in the small proximal fragment.

Question 239

Topic: Wrist & Carpus

A 28-year-old male sustains a Galeazzi fracture. Following open reduction and internal fixation of the radial shaft, the distal radioulnar joint (DRUJ) remains grossly unstable in all forearm positions. What is the most appropriate first step in management?

. Long arm casting in neutral rotation
. Open repair of the triangular fibrocartilage complex (TFCC)
. Transfixing the DRUJ with K-wires for 4 to 6 weeks
. Distal ulna resection
. Re-evaluating the radial reduction for malrotation or shortening

Correct Answer & Explanation

. Re-evaluating the radial reduction for malrotation or shortening

Explanation

In a Galeazzi fracture, the most common cause of persistent DRUJ instability after fixation of the radius is non-anatomic reduction (shortening or malrotation) of the radial shaft. The surgeon must first re-evaluate and perfectly correct the radius fixation before addressing the TFCC directly or pinning the joint.

Question 240

Topic: Wrist & Carpus

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

. EPL tendon rupture from dorsal screw prominence
. FPL tendon rupture from plate prominence distal to the watershed line
. Anterior interosseous nerve palsy from surgical traction
. FDP tendon rupture from prominent ulnar screws
. Adhesions of the FCR tendon within its sheath

Correct Answer & Explanation

. FPL tendon rupture from plate prominence distal to the watershed line

Explanation

Placement of a volar plate distal to the watershed line of the distal radius can cause mechanical attrition and subsequent rupture of the flexor pollicis longus (FPL) tendon. The watershed line marks the safe distal limit for hardware placement.

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