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Wrist & Carpus MCQs

Practice Set 28 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 541

Topic: Wrist & Carpus

The 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) vascularized bone graft is commonly used for scaphoid nonunions. This artery courses between which two extensor compartments?

. Abductor pollicis longus/Extensor pollicis brevis and Extensor carpi radialis longus/brevis
. Extensor carpi radialis longus/brevis and Extensor pollicis longus
. Extensor pollicis longus and Extensor digitorum communis
. Extensor digitorum communis and Extensor digiti minimi
. Extensor digiti minimi and Extensor carpi ulnaris

Correct Answer & Explanation

. Abductor pollicis longus/Extensor pollicis brevis and Extensor carpi radialis longus/brevis

Explanation

The 1,2 ICSRA runs longitudinally along the distal radius between the first extensor compartment (APL, EPB) and the second extensor compartment (ECRL, ECRB). It is used as a pedicle for distal radius bone grafts to the scaphoid.

Question 542

Topic: Wrist & Carpus

During a radial styloidectomy for SNAC Stage I arthritis, the surgeon must be careful not to excise more than 3 to 4 mm of the radial styloid. Excessive resection risks destabilizing the carpus by detaching which of the following ligaments?

. Radioscaphocapitate (RSC) ligament
. Scapholunate interosseous ligament
. Lunotriquetral interosseous ligament
. Dorsal radiocarpal ligament
. Ulnocarpal ligament complex

Correct Answer & Explanation

. Radioscaphocapitate (RSC) ligament

Explanation

The radioscaphocapitate (RSC) ligament originates from the radial styloid. Excision of more than 3 to 4 mm of the styloid can compromise the origin of this critical volar stabilizing ligament, leading to ulnar translation of the carpus.

Question 543

Topic: Wrist & Carpus
A patient presents with a long-standing scaphoid nonunion. CT demonstrates advanced cystic changes and joint space loss at the capitolunate joint, but the radioscaphoid joint is relatively well preserved. What is the most appropriate management principle for this atypical pattern?
. It is managed as a SNAC I with isolated radial styloidectomy
. It requires isolated capitolunate fusion while preserving the scaphoid
. It is managed identically to SLAC I using scapholunate repair
. It is an absolute indication for total wrist arthroplasty regardless of age
. It is managed as a SNAC III equivalent due to capitate involvement, often requiring four-corner fusion

Correct Answer & Explanation

. It is managed as a SNAC III equivalent due to capitate involvement, often requiring four-corner fusion

Explanation

Although SNAC progression typically affects the radioscaphoid joint before the capitolunate joint, isolated capitolunate arthritis with a scaphoid nonunion dictates the same salvage treatment principles as SNAC III. Four-corner fusion is typically required.

Question 544

Topic: Wrist & Carpus

A 45-year-old man with Scaphoid Nonunion Advanced Collapse (SNAC) Stage II undergoes evaluation for a salvage procedure. He strongly prefers a proximal row carpectomy (PRC) over a four-corner arthrodesis. Which of the following intraoperative findings represents an absolute contraindication to proceeding with a PRC?

. Extensive osteophyte formation at the radial styloid
. Eburnation and loss of articular cartilage on the proximal capitate head
. Sclerosis of the lunate facet of the distal radius
. A scapholunate angle of 75 degrees
. Complete disruption of the scapholunate interosseous ligament

Correct Answer & Explanation

. Extensive osteophyte formation at the radial styloid

Explanation

Proximal row carpectomy relies on a congruent and healthy articulation between the capitate head and the lunate fossa of the radius. Eburnation or severe arthritis of the proximal capitate is an absolute contraindication to PRC, necessitating a four-corner fusion or total wrist arthrodesis instead.

Question 545

Topic: Wrist & Carpus

In the natural history and progression of Scaphoid Nonunion Advanced Collapse (SNAC), which specific articular surface is classically preserved until the final stage (Stage IV) of pancarpal arthritis?

. Radioscaphoid joint
. Scaphocapitate joint
. Capitolunate joint
. Radiolunate joint
. Trapeziometacarpal joint

Correct Answer & Explanation

. Radioscaphoid joint

Explanation

The radiolunate joint is characteristically spared in both SLAC and SNAC wrists due to the concentric, spherical nature of the lunate fossa, which prevents abnormal translation and shear. It only becomes involved in end-stage (Stage IV) pancarpal arthritis.

Question 546

Topic: Wrist & Carpus

A 65-year-old woman undergoes volar plate fixation for a displaced distal radius fracture. Six months postoperatively, she presents complaining of a sudden inability to bend the tip of her thumb. What is the most likely cause of this complication?

. Attritional rupture of the flexor pollicis longus (FPL) tendon
. Iatrogenic injury to the anterior interosseous nerve
. Unrecognized injury to the recurrent motor branch of the median nerve
. Nonunion of the distal radius
. Rupture of the extensor pollicis longus (EPL) tendon

Correct Answer & Explanation

. Attritional rupture of the flexor pollicis longus (FPL) tendon

Explanation

Volar plating of the distal radius places the flexor tendons, particularly the FPL, at risk for attritional rupture if the plate is positioned distal to the watershed line of the distal radius. The loss of active interphalangeal flexion of the thumb characterizes an FPL rupture. EPL rupture is more common after nonoperative management or dorsal plating of distal radius fractures.

Question 547

Topic: Wrist & Carpus

A 60-year-old female presents with an inability to flex the interphalangeal joint of her right thumb. She underwent open reduction and internal fixation of a distal radius fracture using a volar locking plate 6 months ago. What is the most likely pathophysiological cause of this complication?

. The plate was placed proximal to the watershed line
. A prominently long screw tip protruding through the dorsal cortex
. The plate was placed distal to the watershed line
. Iatrogenic transection of the flexor pollicis longus tendon during the initial surgical approach
. Attritional rupture of the extensor pollicis longus tendon

Correct Answer & Explanation

. The plate was placed proximal to the watershed line

Explanation

Attritional rupture of the flexor pollicis longus (FPL) tendon is a well-documented complication of volar plating of the distal radius. This typically occurs when the plate is positioned too far distally, crossing the 'watershed line' (the distal margin of the pronator fossa), which causes the FPL tendon to rub directly against the prominent distal edge of the plate during finger movement.

Question 548

Topic: Wrist & Carpus

Complex Regional Pain Syndrome (CRPS) is a devastating complication following distal radius fractures. Based on prospective randomized controlled trials, which of the following oral supplements has been recommended to be taken daily for 50 days to decrease the incidence of CRPS?

. Vitamin B6 (Pyridoxine) 100 mg
. Vitamin C (Ascorbic acid) 500 mg
. Vitamin D3 (Cholecalciferol) 2000 IU
. Calcium carbonate 1000 mg
. Glucosamine sulfate 1500 mg

Correct Answer & Explanation

. Vitamin B6 (Pyridoxine) 100 mg

Explanation

Multiple studies (most notably Zollinger et al.) have demonstrated that administering Vitamin C (500 mg daily for 50 days) after a distal radius fracture significantly reduces the risk of developing Complex Regional Pain Syndrome (CRPS), likely through its role as an antioxidant scavenging free radicals.

Question 549

Topic: Wrist & Carpus

Following closed reduction and casting of a distal radius fracture, which of the following pharmacological interventions has been supported by randomized controlled trials as an effective prophylactic measure to reduce the incidence of Complex Regional Pain Syndrome (CRPS)?

. Daily administration of Vitamin C 500 mg
. Immediate initiation of an oral corticosteroid taper
. Prophylactic gabapentin 300 mg three times daily
. Application of a topical lidocaine patch
. Early administration of a stellate ganglion block

Correct Answer & Explanation

. Daily administration of Vitamin C 500 mg

Explanation

Multiple studies, including randomized controlled trials, have demonstrated that the administration of Vitamin C (typically 500 mg daily for 50 days) following a distal radius fracture significantly reduces the risk of developing CRPS type I.

Question 550

Topic: Wrist & Carpus

An orthopedic investigator conducts a randomized controlled trial comparing two surgical techniques for distal radius fractures. The study concludes there is no significant difference between the two treatments (p = 0.08), but a post-hoc power analysis reveals the study power was only 60%. Which of the following statements is mathematically true regarding this study design?

. There is an 8% chance of a Type I error.
. The study has a 40% probability of a Type II error.
. The study is adequately powered to detect a clinically meaningful difference.
. Increasing the sample size would predictably decrease the power of the study.
. A Type I error definitively occurred.

Correct Answer & Explanation

. There is an 8% chance of a Type I error.

Explanation

Statistical power is the probability of correctly rejecting the null hypothesis when it is false, defined as (1 - Beta). If the power is 60%, then Beta (the probability of a Type II error, or failing to reject a false null hypothesis) is 40%. Because the study is underpowered (standard convention requires >80% power), there is a high risk that a true difference exists but was not detected due to insufficient sample size.

Question 551

Topic: Wrist & Carpus

A 55-year-old female who underwent open reduction and internal fixation of a distal radius fracture with a volar locking plate 9 months ago presents with a sudden inability to flex the interphalangeal (IP) joint of her thumb. Which of the following technical errors during the initial surgery is the most likely cause of this complication?

. Placement of the volar plate distal to the watershed line
. Over-penetration of screws through the dorsal cortex
. Failure to repair the pronator quadratus muscle over the plate
. Placement of the plate too proximal on the radial diaphysis
. Excessive radial inclination of the plate

Correct Answer & Explanation

. Placement of the volar plate distal to the watershed line

Explanation

The patient has sustained an iatrogenic rupture of the Flexor Pollicis Longus (FPL) tendon, which is a known complication of volar plating for distal radius fractures. The "watershed line" is a transverse ridge on the volar distal radius, marking the distal margin of the pronator fossa. If a plate is placed distal to this line, it sits prominently and rubs against the overlying flexor tendons (most commonly the FPL), leading to tenosynovitis, attrition, and eventual rupture. Dorsal screw over-penetration endangers the extensor tendons (e.g., EPL).

Question 552

Topic: Wrist & Carpus

A 60-year-old woman is treated non-operatively in a cast for a minimally displaced Colles fracture. Six weeks later, after cast removal, she suddenly loses the ability to actively extend her thumb interphalangeal joint. What is the most appropriate definitive management for this complication?

. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer
. Primary end-to-end repair of the EPL tendon
. Tendon graft using the palmaris longus
. Immobilization in a thumb spica splint for 6 weeks
. Release of the first dorsal compartment

Correct Answer & Explanation

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

Explanation

Spontaneous rupture of the EPL tendon post-distal radius fracture is due to ischemia or attrition over Lister's tubercle. Because the tendon ends retract and degenerate, primary repair is usually impossible, making an EIP to EPL transfer the gold standard.

Question 553

Topic: Wrist & Carpus
A 55-year-old manual laborer presents with chronic wrist pain. Radiographs reveal advanced scapholunate advanced collapse (SLAC) with degenerative changes involving the radioscaphoid joint and the entire scaphoid facet of the radius, sparing the capitolunate joint. What SLAC stage does this represent?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage II

Explanation

SLAC Stage II involves osteoarthritis of the entire radioscaphoid joint. Stage III involves the capitolunate joint, and Stage I is limited to the radial styloid-scaphoid articulation.

Question 554

Topic: Wrist & Carpus

A 45-year-old female sustains a non-displaced fracture of the distal radius. Four weeks later, she presents with sudden inability to actively extend the interphalangeal joint of her thumb. Which of the following is the most likely cause of this complication?

. Iatrogenic nerve injury during casting
. Extensor pollicis longus attrition over Lister's tubercle
. Ischemic contracture of the forearm
. Unrecognized rupture of the flexor pollicis longus
. Extensor pollicis brevis entrapment in the first dorsal compartment

Correct Answer & Explanation

. Iatrogenic nerve injury during casting

Explanation

Extensor pollicis longus (EPL) tendon rupture is a known complication of non-displaced distal radius fractures. It typically occurs due to mechanical attrition over the fracture callus at Lister's tubercle or localized ischemia.

Question 555

Topic: Wrist & Carpus

A 60-year-old woman undergoes volar plate fixation for a displaced distal radius fracture. Four months postoperatively, she suddenly loses the ability to actively flex her thumb interphalangeal joint. This complication is most directly related to plate placement distal to which anatomic landmark?

. Lister's tubercle
. The watershed line
. The sigmoid notch
. The radial styloid
. The ulnar styloid

Correct Answer & Explanation

. Lister's tubercle

Explanation

Placement of a volar plate distal to the watershed line of the distal radius causes hardware prominence. This can lead to attritional rupture of the flexor pollicis longus (FPL) tendon.

Question 556

Topic: Wrist & Carpus

A 40-year-old manual laborer presents with wrist pain and a known scaphoid nonunion. Radiographs reveal Scaphoid Nonunion Advanced Collapse (SNAC) Stage II. Which of the following best describes the pattern of arthritic involvement in this stage?

. Arthritis limited to the radial styloid
. Arthritis of the entire radioscaphoid joint
. Arthritis involving both the radioscaphoid and capitolunate joints
. Isolated radiolunate arthritis
. Pancarpal arthritis including the radioulnar joint

Correct Answer & Explanation

. Arthritis limited to the radial styloid

Explanation

SNAC Stage II is characterized by osteoarthritis involving the entire radioscaphoid joint. The radiolunate joint is typically spared in all SNAC stages due to its congruent spherical articulation, distinguishing it from the elliptical radioscaphoid joint.

Question 557

Topic: Wrist & Carpus

A 55-year-old female undergoes volar locked plating for a distal radius fracture. At her 6-month follow-up, she presents with an inability to actively flex the interphalangeal joint of her thumb. This complication is most highly associated with plate placement distal to which anatomic landmark?

. Lister's tubercle
. The watershed line
. The sigmoid notch
. The volar radioulnar ligament
. The pronator quadratus insertion

Correct Answer & Explanation

. Lister's tubercle

Explanation

Placement of a volar plate distal to the watershed line of the distal radius places the hardware in direct contact with the flexor tendons. This prominent hardware causes irritation and can lead to rupture of the flexor pollicis longus (FPL) tendon.

Question 558

Topic: Wrist & Carpus

A 45-year-old female presents with the inability to actively extend her thumb interphalangeal joint 3 months after undergoing open reduction and internal fixation of a distal radius fracture with a volar locking plate. Radiographs reveal a healed fracture with a prominent screw protruding through the dorsal cortex. What is the most likely diagnosis?

. Flexor pollicis longus rupture
. Extensor pollicis longus rupture
. Extensor indicis proprius rupture
. Flexor digitorum profundus rupture
. Extensor digitorum communis rupture

Correct Answer & Explanation

. Flexor pollicis longus rupture

Explanation

Extensor pollicis longus (EPL) rupture is a known complication of distal radius fractures treated with volar plating. It typically occurs due to mechanical attrition and friction over prominent dorsal screws that protrude past the dorsal cortex.

Question 559

Topic: Wrist & Carpus

A 42-year-old falls from a ladder, sustaining a comminuted, unsalvageable radial head fracture. Wrist pain is also noted, and distal radioulnar joint (DRUJ) instability is confirmed. Which of the following is strictly contraindicated in this patient's management?

. Radial head excision alone
. Radial head arthroplasty
. TFCC repair
. Ulnar shortening osteotomy
. Pinning of the DRUJ in supination

Correct Answer & Explanation

. Radial head excision alone

Explanation

This patient has an Essex-Lopresti injury, characterized by a radial head fracture, interosseous membrane tear, and DRUJ disruption. Radial head excision alone is strictly contraindicated as it removes the primary restraint to proximal radial migration, leading to severe ulnocarpal impaction.

Question 560

Topic: Wrist & Carpus

Which of the following radiographic parameters is the most critical to restore to prevent long-term radiocarpal arthrosis following surgical fixation of an intra-articular distal radius fracture?

. Volar tilt
. Radial inclination
. Radial height
. Articular step-off
. Ulnar variance

Correct Answer & Explanation

. Volar tilt

Explanation

While restoring extra-articular alignment parameters is important for kinematics, restoring articular congruity (minimizing step-off to less than 1-2 mm) is the single most critical factor in preventing the development of post-traumatic radiocarpal arthrosis after an intra-articular fracture.

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