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 21
Topic: Wrist & Carpus
A 45-year-old male presents with chronic wrist pain and a scaphoid nonunion. Radiographs demonstrate degenerative changes isolated to the radioscaphoid and scaphocapitate joints. The radiolunate articulation is preserved. What is the SNAC classification and an appropriate surgical option?
Correct Answer & Explanation
. SNAC Stage II treated with scaphoid excision and four-corner fusion
Explanation
SNAC Stage II involves arthritis of the radioscaphoid and scaphocapitate joints. Appropriate salvage options include scaphoid excision with four-corner fusion or a proximal row carpectomy (if the capitate head is preserved).
Question 22
Topic: Wrist & Carpus
Regarding the surgical management of unstable Colles fractures with volar locking plates, which anatomical landmark is crucial to avoid hardware impingement on the flexor tendons and potential rupture?
Correct Answer & Explanation
. The volar watershed line
Explanation
Correct Answer: CThe volar watershed line is a critical anatomical landmark in volar plating of distal radius fractures. Plates placed distal to this line, or with screws protruding distally, risk irritation and rupture of the flexor tendons, particularly the flexor pollicis longus (FPL). The watershed line represents the ridge where the volar capsule and ligaments attach, marking the safe zone for plate placement proximally. Lister's tubercle is on the dorsal aspect, the pronator quadratus covers the plate proximally and protects tendons, but proper plate positioning relative to the articular surface, guided by the watershed line, is paramount for preventing distal tendon impingement.
Question 23
Topic: Wrist & Carpus
Which of the following is NOT typically considered a stable parameter after closed reduction of a Colles fracture?
Correct Answer & Explanation
. Articular step-off of 3 mm
Explanation
Correct Answer: DAn articular step-off of 3 mm is NOT considered a stable or acceptable parameter. Generally, an articular step-off or gap of >2 mm is considered unstable and an indication for surgical management, especially in active patients, due to the high risk of post-traumatic arthritis. Radial inclination of 22 degrees, volar tilt of 5 degrees (neutral to slight volar is acceptable for Colles), radial length difference of 2 mm (usually <3mm difference is acceptable), and ulnar variance of 0 mm (neutral) are all generally within acceptable post-reduction radiographic parameters for stable Colles fractures.
Question 24
Topic: Wrist & Carpus
Which classification system for distal radius fractures emphasizes the involvement of the radiocarpal and radioulnar joints?
Correct Answer & Explanation
. Frykman classification
Explanation
Correct Answer: BThe Frykman classification system is widely used for distal radius fractures and is based on the involvement of the radiocarpal and radioulnar joints (articular vs. extra-articular, and presence/absence of ulnar styloid fracture). The AO classification is more complex and describes fracture patterns by location (metaphyseal), articular involvement (extra-articular, partial articular, complete articular), and comminution. Gartland and Werley primarily assess outcome. Universal classification is another system that considers similar parameters as Frykman. Fernandez classification is based on the mechanism of injury and fracture morphology.
Question 25
Topic: Wrist & Carpus
A 25-year-old male sustains a closed volar Barton's fracture of the distal radius after a motorcycle accident. Which of the following is the most appropriate surgical treatment strategy to restore articular congruity and prevent displacement?
Correct Answer & Explanation
. Volar buttress plating
Explanation
A volar Barton's fracture is a volar shear fracture of the distal radius with radiocarpal subluxation. Volar buttress plating is the gold standard as it mechanically blocks the volar displacement of the articular fragment and carpus.
Question 26
Topic: Wrist & Carpus
A 45-year-old man presents with chronic wrist pain. Radiographs reveal a scaphoid waist nonunion with advanced radioscaphoid arthritis, but the midcarpal joint is spared. What is the correct classification for this pattern of arthritis?
Correct Answer & Explanation
. SNAC Stage II
Explanation
Scaphoid Nonunion Advanced Collapse (SNAC) Stage II involves arthritis extending to the entire radioscaphoid joint. Stage I involves only the radial styloid, while Stage III involves the capitolunate joint.
Question 27
Topic: Wrist & Carpus
A 32-year-old female presents after a fall onto an outstretched hand. Radiographs reveal a volar shear fracture of the distal radius with subluxation of the carpus (volar Barton's fracture). What is the optimal biomechanical fixation method for this specific fracture pattern?
Correct Answer & Explanation
. Volar buttress plate
Explanation
A volar Barton's fracture involves an unstable volar shear fragment that allows the carpus to subluxate volarly. A volar plate applied in a buttress mode best neutralizes these shear forces and maintains joint congruity.
Question 28
Topic: Wrist & Carpus
A 65-year-old female undergoes volar locked plating of a distal radius fracture. Four weeks postoperatively, she suddenly loses the ability to actively extend her thumb interphalangeal joint. What is the most likely cause?
Correct Answer & Explanation
. Rupture of the extensor pollicis longus tendon
Explanation
Extensor pollicis longus (EPL) tendon rupture is a known complication of distal radius fractures and their fixation. It is often caused by prominent dorsal screw penetration or regional ischemia, presenting as a sudden loss of active thumb IP extension.
Question 29
Topic: Wrist & Carpus
A 22-year-old male sustains a proximal pole scaphoid fracture. What anatomical characteristic of the scaphoid's blood supply places him at a high risk for avascular necrosis?
Correct Answer & Explanation
. Distal to proximal retrograde intraosseous perfusion
Explanation
The scaphoid receives its primary blood supply from branches of the radial artery that enter the distal pole and travel retrograde within the bone. Proximal pole fractures disrupt this flow, creating a high risk of avascular necrosis.
Question 30
Topic: Wrist & Carpus
A 60-year-old female undergoes volar locking plate fixation for a distal radius fracture. Six months later, she presents with an inability to flex her thumb interphalangeal joint. Plate prominence at which anatomical landmark is most responsible for this complication?
Correct Answer & Explanation
. Watershed line
Explanation
Prominence of the volar plate distal to the watershed line significantly increases the risk of flexor pollicis longus (FPL) tendon attrition and rupture. Proper plate placement avoids bridging this critical landmark.
Question 31
Topic: Wrist & Carpus
A 60-year-old female undergoes open reduction and internal fixation of a distal radius fracture using a volar locking plate. Four months postoperatively, she presents unable to actively flex the interphalangeal (IP) joint of her thumb. Which tendon has most likely ruptured, and what surgical technical error primarily increases the risk of this complication?
Correct Answer & Explanation
. Flexor pollicis longus; placement of the volar plate distal to the watershed line.
Explanation
Flexor pollicis longus (FPL) tendon rupture is a well-known complication of volar plating for distal radius fractures. It occurs due to attritional wear when the plate is positioned too distally, projecting volar to the "watershed line" of the distal radius.
Question 32
Topic: Wrist & Carpus
You are presented with a simulated clinical scenario: a 45-year-old male with a displaced distal radius fracture. When asked to 'discuss your management,' which initial framework demonstrates the MOST structured and comprehensive approach expected by an examiner?
Correct Answer & Explanation
. Outlining a systematic approach encompassing initial assessment, history, examination, investigations, non-operative vs. operative considerations, informed consent, post-operative care, rehabilitation, and potential complications.
Explanation
Correct Answer: CExaminers seek a structured, systematic approach that demonstrates a holistic understanding of patient care, not just technical surgical skills. An initial framework that covers the entire patient journey – from diagnosis (history, exam, investigations) through treatment decisions (non-op vs. op), patient communication (consent), and post-treatment considerations (post-op care, rehabilitation, complications) – demonstrates comprehensive clinical reasoning. While classification and latest research are important, they fit within this broader framework, not as the initial statement of management. Delaying an answer or over-focusing on a single aspect can suggest a lack of structured thinking.
Question 33
Topic: Wrist & Carpus
A 28-year-old laborer presents with chronic radial-sided wrist pain 18 months after a fall. Radiographs demonstrate a scaphoid waist nonunion with a humpback deformity, dorsal intercalated segment instability (DISI), and established radiocarpal arthrosis. Which of the following is the most appropriate surgical management?
Correct Answer & Explanation
. Scaphoid excision and four-corner fusion
Explanation
Scaphoid excision and four-corner fusion is indicated for scaphoid nonunion advanced collapse (SNAC) with established radiocarpal arthrosis. Bone grafting to achieve union is contraindicated once significant degenerative changes have developed in the midcarpal or radiocarpal joints.
Question 34
Topic: Wrist & Carpus
According to Mayfield's stages of perilunate instability, a stage III injury is characterized by the disruption of which of the following ligaments?
Correct Answer & Explanation
. Lunotriquetral interosseous ligament
Explanation
Mayfield stage I involves the scapholunate ligament, and stage II involves capsular disruption allowing dorsal capitate dislocation. Stage III involves disruption of the lunotriquetral interosseous ligament, separating the lunate from the triquetrum.
Question 35
Topic: Wrist & Carpus
During the initial stage of a perilunate dissociation (Mayfield Stage I), isolated disruption of the scapholunate interosseous ligament occurs. If left untreated, this specific ligamentous failure predominantly results in which radiographic deformity over time?
Correct Answer & Explanation
. Dorsal intercalated segment instability (DISI)
Explanation
Disruption of the scapholunate ligament allows the lunate to extend abnormally with the triquetrum, while the scaphoid flexes. This abnormal dorsal tilt of the lunate presents radiographically as a Dorsal Intercalated Segment Instability (DISI) deformity.
Question 36
Topic: Wrist & Carpus
A 28-year-old male sustains a transscaphoid perilunate fracture-dislocation. Despite prompt and anatomic open reduction and internal fixation, the patient remains at high risk for which of the following long-term complications due to the inherent vascular anatomy?
Correct Answer & Explanation
. Avascular necrosis of the proximal pole of the scaphoid
Explanation
Transscaphoid perilunate dislocations carry a high risk of nonunion and avascular necrosis (AVN) of the proximal pole of the scaphoid. This is due to the retrograde intraosseous blood supply entering the scaphoid distally, which is disrupted by the fracture.
Question 37
Topic: Wrist & Carpus
A 40-year-old mechanic complains of chronic dorsal wrist pain. Radiographs demonstrate a scapholunate gap of 4 mm, a 'cortical ring sign', and narrowing of the radioscaphoid articulation, while the midcarpal joint is preserved. This radiographic pattern is most consistent with which stage of Scapholunate Advanced Collapse (SLAC)?
Correct Answer & Explanation
. Stage II SLAC
Explanation
SLAC staging follows a predictable pattern of arthritic progression. Stage I involves the radial styloid; Stage II involves the entire radioscaphoid fossa; and Stage III progresses to involve the capitolunate joint. The midcarpal joint is preserved here, placing it in Stage II.
Question 38
Topic: Wrist & Carpus
During open reduction and internal fixation of a distal third radial shaft fracture (Galeazzi fracture), the surgeon assesses the distal radioulnar joint (DRUJ) for instability. Which of the following intraoperative findings most strongly indicates the need for DRUJ stabilization?
Correct Answer & Explanation
. Gross translation of the ulna relative to the radius in neutral rotation after rigid radius fixation
Explanation
Following rigid fixation of the radius in a Galeazzi fracture, the DRUJ must be assessed. Gross instability in neutral or all forearm positions dictates the need for DRUJ stabilization, typically via radioulnar pinning in supination or open TFCC repair.
Question 39
Topic: Wrist & Carpus
Which of the following is an absolute indication for operative intervention in an acute scaphoid waist fracture?
Correct Answer & Explanation
. Displacement greater than 1 mm
Explanation
Displacement of greater than 1 mm in an acute scaphoid fracture is an absolute indication for surgical fixation due to the high risk of nonunion and subsequent Scaphoid Nonunion Advanced Collapse (SNAC). Proximal pole fractures are a strong relative indication.
Question 40
Topic: Wrist & Carpus
A 60-year-old female sustained a non-displaced distal radius fracture treated conservatively in a short arm cast. Six weeks later, she reports a sudden inability to actively extend the interphalangeal joint of her thumb. What is the primary pathophysiology behind this specific complication?
Correct Answer & Explanation
. Ischemia of the tendon due to hematoma and edema within an intact third dorsal compartment
Explanation
Extensor pollicis longus (EPL) ruptures following non-displaced distal radius fractures are primarily ischemic in nature. The intact extensor retinaculum of the third dorsal compartment restricts swelling, leading to increased pressure, decreased synovial perfusion, and subsequent tendon necrosis and rupture.
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