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Wrist & Carpus MCQs

Practice Set 7 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 121

Topic: Wrist & Carpus

A 50-year-old female undergoes open reduction and internal fixation of a distal radius fracture with a volar locking plate. Six months postoperatively, she presents with an inability to actively flex the interphalangeal joint of her thumb. Which of the following technical errors during the index procedure is most likely responsible for this complication?

. Placement of the plate dorsal to the extensor pollicis longus tendon
. Placement of the plate distal to the watershed line
. Use of excessively long screws penetrating the dorsal cortex
. Failure to release the brachioradialis insertion
. Inadequate reduction of the dorsal tilt

Correct Answer & Explanation

. Placement of the plate distal to the watershed line

Explanation

The patient has sustained an iatrogenic rupture of the flexor pollicis longus (FPL) tendon. This is a well-documented complication of volar locked plating for distal radius fractures. It most commonly occurs when the plate is positioned too far distally, extending past the 'watershed line' (the bony ridge at the distal margin of the pronator fossa). This prominent distal hardware creates mechanical friction against the FPL tendon, ultimately leading to fraying and rupture.

Question 122

Topic: Wrist & Carpus

Six weeks after closed reduction and cast immobilization for a non-displaced distal radius fracture, a 55-year-old female presents with a sudden inability to actively extend her thumb interphalangeal joint. What is the preferred surgical management?

. Primary end-to-end repair of the extensor pollicis longus (EPL) tendon
. Extensor indicis proprius (EIP) to EPL tendon transfer
. Free tendon graft reconstruction of the EPL using palmaris longus
. Extensor carpi radialis longus (ECRL) to EPL tendon transfer
. First dorsal compartment release

Correct Answer & Explanation

. Extensor indicis proprius (EIP) to EPL tendon transfer

Explanation

Delayed spontaneous rupture of the extensor pollicis longus (EPL) tendon is a known complication of non-displaced distal radius fractures. Because the tendon ends are typically frayed and retracted, primary repair is usually impossible, making an EIP to EPL tendon transfer the gold standard treatment.

Question 123

Topic: Wrist & Carpus

A 65-year-old woman presents with the inability to extend her thumb interphalangeal joint. Six weeks prior, she sustained a non-displaced distal radius fracture treated with cast immobilization. Examination confirms rupture of the Extensor Pollicis Longus (EPL) tendon. Which of the following is the most appropriate and reliable surgical treatment?

. Primary end-to-end repair of the EPL
. Extensor Indicis Proprius (EIP) to EPL tendon transfer
. Extensor Carpi Radialis Longus (ECRL) to EPL tendon transfer
. Thumb interphalangeal joint arthrodesis
. Tendon grafting using palmaris longus

Correct Answer & Explanation

. Extensor Indicis Proprius (EIP) to EPL tendon transfer

Explanation

Delayed EPL rupture is a known complication of both operatively and non-operatively treated distal radius fractures, often secondary to ischemic changes or mechanical attrition at the Lister tubercle. Because the tendon ends are typically retracted and degenerated, primary end-to-end repair is rarely feasible. An Extensor Indicis Proprius (EIP) to EPL transfer is the gold standard, providing appropriate excursion, tension, and a reliable functional outcome without significant donor site morbidity.

Question 124

Topic: Wrist & Carpus

A 45-year-old female undergoes volar locked plating for a comminuted distal radius fracture. Postoperatively, she develops a spontaneous rupture of the flexor pollicis longus (FPL) tendon. Which of the following technical errors during surgery is the most significant risk factor for this complication?

. Placement of the volar plate distal to the watershed line (Soong Grade 2)
. Failure to repair the pronator quadratus muscle
. Use of locking screws rather than non-locking screws
. Over-penetration of dorsal cortical screws
. Placement of the plate proximal to the watershed line (Soong Grade 0)

Correct Answer & Explanation

. Placement of the volar plate distal to the watershed line (Soong Grade 2)

Explanation

FPL tendon rupture is a known complication of volar plating of the distal radius. Placement of the plate distal to the watershed line (Soong Grade 2) causes the plate to sit proud, creating mechanical attrition on the FPL tendon.

Question 125

Topic: Wrist & Carpus

Following volar locking plate fixation of a distal radius fracture, a patient develops attrition and rupture of the flexor pollicis longus (FPL) tendon. Which radiographic parameter on the postoperative lateral view is most highly predictive of this complication?

. Prominence of the plate volar to the critical line of Soong (Soong Grade 2)
. Dorsal screw penetration into the radiocarpal joint
. Plate placement proximal to the pronator quadratus footprint
. Use of non-locking cortical screws in the distal row
. Radial translation of the distal plate border

Correct Answer & Explanation

. Prominence of the plate volar to the critical line of Soong (Soong Grade 2)

Explanation

Plate prominence volar to the watershed line, classified as Soong Grade 2, significantly increases the risk of flexor tendon irritation. This mechanical conflict most commonly leads to rupture of the flexor pollicis longus (FPL).

Question 126

Topic: Wrist & Carpus

A 60-year-old female presents with a sudden inability to flex her thumb interphalangeal joint 6 months following volar locked plating of a distal radius fracture. Which of the following plate positions is the most likely biomechanical cause of this complication?

. Placement dorsal to the Lister tubercle
. Placement proximal to the pronator quadratus insertion
. Placement distal to the watershed line
. Placement with excessive radial inclination
. Placement extending into the distal radioulnar joint space

Correct Answer & Explanation

. Placement distal to the watershed line

Explanation

Flexor pollicis longus (FPL) rupture is a known complication of volar distal radius plating. It is most frequently caused by placement of the plate distal to the watershed line, leading to mechanical attrition of the tendon against the prominent plate edge.

Question 127

Topic: Wrist & Carpus
According to Mayfield's progressive stages of perilunate instability, a Stage III injury is characterized by the disruption of which of the following structures, leading to a complete perilunate dislocation?
. Scapholunate interosseous ligament
. Radioscaphocapitate ligament
. Lunotriquetral interosseous ligament
. Dorsal radiocarpal ligament
. Volar radiolunate ligament

Correct Answer & Explanation

. Lunotriquetral interosseous ligament

Explanation

Mayfield staging describes the progressive ligamentous disruption around the lunate. Stage I is scapholunate, Stage II involves the space of Poirier (capitolunate), Stage III is lunotriquetral disruption (resulting in perilunate dislocation), and Stage IV is lunate dislocation.

Question 128

Topic: Wrist & Carpus

A 45-year-old male sustains a volar marginal articular fracture of the distal radius (volar Barton's fracture) with volar subluxation of the carpus. During open reduction and internal fixation via an FCR approach, which of the following stout ligamentous structures remains attached to the volar fracture fragment, exerting the primary proximal and volar displacing force on the carpus?

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

Correct Answer & Explanation

. Radioscaphocapitate ligament

Explanation

In a volar Barton's fracture (volar shear fracture of the distal radius), the strong volar radiocarpal ligaments—specifically the radioscaphocapitate (RSC) and the long/short radiolunate ligaments—remain attached to the avulsed volar bony fragment. Because the carpus is tethered to this fragment via these ligaments, the entire carpus subluxates volarly and proximally along with the fracture fragment.

Question 129

Topic: Wrist & Carpus

A 29-year-old male undergoes open reduction and internal fixation for a Galeazzi fracture (distal one-third radial shaft fracture). Following anatomic and rigid fixation of the radius, the distal radioulnar joint (DRUJ) remains highly unstable to dorsal translation of the ulna. The surgeon decides to temporarily pin the DRUJ. In what position is the forearm most commonly pinned to maximize DRUJ stability?

. Maximum pronation
. Neutral rotation
. Maximum supination
. 45 degrees of pronation
. 90 degrees of flexion at the elbow

Correct Answer & Explanation

. Maximum supination

Explanation

Following a Galeazzi fracture, if the DRUJ remains unstable after radius fixation, it is typically due to a massive TFCC tear. The position of maximal stability for the DRUJ is supination, as the intact volar radioulnar ligaments become taught, reducing the dorsal subluxation of the ulna.

Question 130

Topic: Wrist & Carpus
  • What is the primary reason for choosing a bone graft substitute rather than an autologous cancellous graft in the treatment of distal radius fractures with metaphyseal comminution and impaction?
. Reduced morbidity
. Improved osteoinduction
. Improved osteoconduction
. More rapid revascularization
. Lower risk of disease transmission

Correct Answer & Explanation

. More rapid revascularization

Explanation

Autologous grafts provide the best osteoinductive and conductive properties. These properties lead to increased revascularization in incorporation of the graft. In the study quoted, there was a 10% minor and 6% major complication rate for iliac crest bone graft harvesting. The most frequent complications included; superficial infections and seromas, as well as minor hematomas. Major complications included herniation of abdominal contents, vascular injury, deep infection or hematoma, and iliac wing fracture.

Question 131

Topic: Wrist & Carpus

In the surgical treatment of a displaced volar Barton's fracture (volar marginal shear fracture of the distal radius), failure to properly reduce and stabilize the volar lunate facet fragment most reliably leads to volar radiocarpal subluxation. This subluxation occurs due to the incompetence of which critical ligament attached to this fragment?

. Radioscaphocapitate ligament
. Long radiolunate ligament
. Short radiolunate ligament
. Dorsal radiocarpal ligament
. Volar radioulnar ligament

Correct Answer & Explanation

. Short radiolunate ligament

Explanation

The volar lunate facet of the distal radius serves as the origin for the short radiolunate ligament, which inserts onto the volar aspect of the lunate. This ligament is the primary restraint preventing volar translation of the lunate and the entire carpus. If the volar lunate facet fracture fragment is not rigidly stabilized with a volar buttress plate, the carpus will subluxate volarly.

Question 132

Topic: Wrist & Carpus

In a patient demonstrating the classic progression of scaphoid nonunion advanced collapse (SNAC), which specific area of the radiocarpal joint is characteristically spared from arthritic changes, even in the late stages of the disease?

. Radioscaphoid articulation
. Scaphocapitate articulation
. Radiolunate articulation
. Capitolunate articulation
. Trapeziometacarpal articulation

Correct Answer & Explanation

. Radiolunate articulation

Explanation

In both SNAC and SLAC wrist pathology, the radiolunate joint is characteristically spared from arthrosis. This is due to the congruent, concentric articulation between the lunate and the lunate fossa of the distal radius, which distributes loads evenly.

Question 133

Topic: Wrist & Carpus

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

. Rupture of the extensor pollicis longus (EPL) tendon
. Rupture of the extensor pollicis brevis (EPB) tendon
. Anterior interosseous nerve (AIN) neuropraxia
. Flexor pollicis longus (FPL) tendon rupture
. Nonunion of the distal radius fracture

Correct Answer & Explanation

. Rupture of the extensor pollicis longus (EPL) tendon

Explanation

EPL tendon rupture is a well-known complication after distal radius fractures. In the setting of volar plating, it is typically caused by prominent dorsal screw tips penetrating the third extensor compartment, leading to attritional wear and sudden rupture.

Question 134

Topic: Wrist & Carpus

A 55-year-old female is unable to extend her thumb interphalangeal joint 6 weeks after non-operative management of a minimally displaced distal radius fracture. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) transfer is planned. Where is the most reliable anatomical landmark to locate the proximal stump of the ruptured EPL tendon?

. Lister's tubercle
. First dorsal compartment
. Fourth dorsal compartment
. Intersection of the first and second compartments
. Volar to the brachioradialis insertion

Correct Answer & Explanation

. Lister's tubercle

Explanation

The EPL tendon wraps directly around Lister's tubercle (occupying the third dorsal compartment), making it the most reliable anatomical landmark. Following spontaneous rupture in a distal radius fracture, the proximal stump typically retracts but is found just proximal to the retinaculum at this location.

Question 135

Topic: Wrist & Carpus
Which of the following represents the correct sequence of degenerative changes seen in Scaphoid Nonunion Advanced Collapse (SNAC)?
. Radioscaphoid joint, followed by lunocapitate joint, followed by radiolunate joint
. Radioscaphoid joint, followed by scaphocapitate joint, followed by lunocapitate joint
. Radiolunate joint, followed by radioscaphoid joint, followed by midcarpal joint
. Scaphotrapezial joint, followed by radioscaphoid joint, followed by lunocapitate joint
. Radioscaphoid joint, followed by radiolunate joint, followed by pisotriquetral joint

Correct Answer & Explanation

. Radioscaphoid joint, followed by scaphocapitate joint, followed by lunocapitate joint

Explanation

SNAC wrist arthritis follows a predictable pattern of progression due to abnormal kinematics of the distal scaphoid fragment. Stage I: arthritis at the radial styloid and distal scaphoid. Stage II: arthritis progresses to the scaphocapitate joint. Stage III: arthritis involves the lunocapitate joint. The radiolunate joint is characteristically spared in both SLAC and SNAC wrists due to its concentric, purely spherical articulation.

Question 136

Topic: Wrist & Carpus

A 28-year-old tennis player presents with ulnar-sided wrist pain and clicking. Examination reveals instability of the distal radioulnar joint (DRUJ) in both supination and pronation. MRI arthrogram demonstrates a full-thickness tear of the triangular fibrocartilage complex (TFCC) at its foveal attachment. Which of the following is the primary stabilizing structure of the DRUJ disrupted in this patient?

. The volar radioulnar ligament
. The dorsal radioulnar ligament
. The radiocarpal ligaments
. The superficial limb of the TFCC attaching to the ulnar styloid
. The deep limb of the TFCC attaching to the fovea

Correct Answer & Explanation

. The deep limb of the TFCC attaching to the fovea

Explanation

The primary stabilizers of the DRUJ are the radioulnar ligaments (volar and dorsal). However, it is the deep (proximal) fibers of these ligaments that converge to attach at the fovea of the ulna (ligamentum subcruentum) that serve as the true isometric axis of rotation and the primary restraint to DRUJ translation. Tears of the superficial attachment to the ulnar styloid (Palmer 1B) typically do not cause gross DRUJ instability, whereas deep foveal avulsions do.

Question 137

Topic: Wrist & Carpus

A 40-year-old female sustains a comminuted distal radius fracture with an associated distal radioulnar joint (DRUJ) dislocation. Intraoperatively, following anatomic volar plate fixation of the distal radius, the DRUJ remains grossly unstable in supination. The ulnar styloid is intact on fluoroscopy. What is the most appropriate next step in management?

. Pinning the DRUJ in pronation for 6 weeks
. Open repair of the deep fibers of the triangular fibrocartilage complex (TFCC) to the fovea
. Ulnar shortening osteotomy
. Darrach procedure
. Reconstruction of the distal oblique bundle

Correct Answer & Explanation

. Open repair of the deep fibers of the triangular fibrocartilage complex (TFCC) to the fovea

Explanation

DRUJ instability after anatomic fixation of the distal radius without an ulnar styloid fracture suggests an avulsion of the deep (foveal) fibers of the TFCC, which are the primary stabilizers of the DRUJ. Direct open or arthroscopic repair of the radioulnar ligaments to their foveal footprint is the most appropriate management to restore stability.

Question 138

Topic: Wrist & Carpus
A 50-year-old male presents with chronic wrist pain and a known history of an untreated scapholunate ligament tear. Radiographs reveal narrowing and sclerosis at the radioscaphoid joint as well as the capitolunate joint. The radiolunate joint is well-preserved. According to the SLAC (Scapholunate Advanced Collapse) classification, which stage is this, and what is an appropriate surgical treatment?
. SLAC I; Scapholunate ligament reconstruction
. SLAC II; Radial styloidectomy
. SLAC III; Proximal row carpectomy or 4-corner fusion
. SLAC IV; Total wrist arthrodesis
. SLAC III; Total wrist arthrodesis

Correct Answer & Explanation

. SLAC III; Proximal row carpectomy or 4-corner fusion

Explanation

This patient has SLAC III arthritis, which involves the radioscaphoid and capitolunate joints while sparing the radiolunate joint. (SLAC I involves only the radial styloid-scaphoid articulation; SLAC II involves the entire radioscaphoid fossa). The standard surgical treatment options for SLAC III are proximal row carpectomy (PRC) or scaphoid excision with 4-corner fusion. Total wrist fusion is typically reserved for SLAC IV (pancarpal, including radiolunate arthritis) or failed salvage.

Question 139

Topic: Wrist & Carpus
In a progressive perilunate instability pattern (Mayfield classification), which ligamentous disruption occurs immediately after the scapholunate ligament fails?
. Lunotriquetral ligament
. Volar radiolunate ligament
. Capitolunate articulation
. Dorsal radiocarpal ligament
. Triangular fibrocartilage complex (TFCC)

Correct Answer & Explanation

. Capitolunate articulation

Explanation

According to Mayfield's stages of perilunate instability, the injury progresses sequentially around the lunate: scapholunate (Stage I), capitolunate (Stage II), lunotriquetral (Stage III), and finally volar dislocation of the lunate (Stage IV).

Question 140

Topic: Wrist & Carpus

What is the most common tendon rupture associated with the placement of a volar locking plate for a distal radius fracture if the plate is positioned distal to the watershed line?

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

Correct Answer & Explanation

. Flexor pollicis longus

Explanation

Placement of a volar plate distal to the watershed line on the distal radius causes prominent hardware to impinge on the flexor tendons, most commonly leading to attritional rupture of the flexor pollicis longus (FPL) tendon.

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