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Wrist & Carpus MCQs

Practice Set 20 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 381

Topic: Wrist & Carpus

A 58-year-old woman undergoes volar locked plating for a displaced distal radius fracture. Six months postoperatively, she presents with a sudden inability to actively flex the interphalangeal joint of her thumb. Radiographs demonstrate that the volar plate is positioned distal to the watershed line. Which of the following is the most likely mechanism for her current deficit?

. Attritional rupture of the flexor pollicis longus tendon
. Compression of the anterior interosseous nerve
. Avulsion of the flexor pollicis brevis
. Rupture of the extensor pollicis longus tendon
. Nonunion of the distal radius fracture

Correct Answer & Explanation

. Attritional rupture of the flexor pollicis longus tendon

Explanation

Placement of a volar plate distal to the watershed line of the distal radius increases the risk of flexor tendon irritation and subsequent attritional rupture. The flexor pollicis longus (FPL) tendon is the most commonly affected due to its close anatomical proximity to the prominent distal edge of the plate. Treatment typically involves plate removal and tendon transfer (e.g., brachioradialis or FDS to FPL) or grafting.

Question 382

Topic: Wrist & Carpus

A 62-year-old woman sustained a minimally displaced distal radius fracture treated nonoperatively in a short arm cast for 6 weeks. Three weeks after cast removal, she suddenly loses the ability to actively extend her thumb interphalangeal joint. She denies any new trauma. What is the most appropriate management?

. Primary repair of the ruptured tendon
. Extensor indicis proprius (EIP) to extensor pollicis longus (EPL) tendon transfer
. Flexor digitorum superficialis (FDS) to EPL tendon transfer
. Splinting for 6 weeks followed by occupational therapy
. Corticosteroid injection into the third dorsal compartment

Correct Answer & Explanation

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

Explanation

Extensor pollicis longus (EPL) tendon ruptures typically occur 3 to 8 weeks after minimally displaced distal radius fractures. This is due to ischemia or mechanical attrition at the Lister tubercle. Because the tendon ends retract and undergo necrosis, primary repair is usually not possible. An EIP to EPL tendon transfer is the gold standard surgical treatment, providing an expendable donor with a matching vector and excursion.

Question 383

Topic: Wrist & Carpus

A 55-year-old woman presents with the inability to actively flex the interphalangeal joint of her right thumb 8 months after undergoing volar locked plating for a distal radius fracture.

Lateral radiographs demonstrate a prominent plate edge over the volar cortex. What is the most likely cause of her current symptom?

. Dorsal penetration of screws causing extensor pollicis longus rupture
. Placement of the plate distal to the watershed line
. Suboptimal reduction of the sigmoid notch
. Injury to the anterior interosseous nerve during the surgical approach
. Unrecognized partial laceration of the tendon during the initial trauma

Correct Answer & Explanation

. Placement of the plate distal to the watershed line

Explanation

The patient has suffered a rupture of the flexor pollicis longus (FPL) tendon, which is a known complication of volar plating of distal radius fractures. The FPL tendon is at particular risk for attrition and rupture when the volar plate is placed distal to the watershed line of the distal radius. This leads to prominence of the hardware that rubs against the tendon during excursion. Dorsal penetration of screws causes extensor tendon irritation or rupture (e.g., EPL), not flexor tendon injury.

Question 384

Topic: Wrist & Carpus
A 35-year-old man fell from a ladder 6 months ago, sustaining a radial head fracture that was treated nonoperatively. He now presents with chronic, progressive wrist pain and ulnar-sided swelling. Examination reveals tenderness at the distal radioulnar joint (DRUJ) and a positive ulnar variance on radiographs. What is the most appropriate management for this chronic condition?
. Radial head arthroplasty alone
. Ulnar shortening osteotomy and radial head arthroplasty
. Distal ulna resection (Darrach procedure)
. Radial head resection and interosseous membrane reconstruction
. Sauvé-Kapandji procedure

Correct Answer & Explanation

. Ulnar shortening osteotomy and radial head arthroplasty

Explanation

The patient has a missed Essex-Lopresti injury (radial head fracture, interosseous membrane tear, and DRUJ disruption). In the chronic setting, longitudinal radioulnar dissociation leads to proximal migration of the radius, causing ulnar impaction and DRUJ arthritis. Treatment requires restoring the radiocapitellar joint and leveling the radioulnar joint. Radial head arthroplasty alone cannot pull the radius back out to length once soft tissues have contracted. Therefore, an ulnar shortening osteotomy combined with radial head arthroplasty is indicated to restore DRUJ congruity and unload the ulnar carpus.

Question 385

Topic: Wrist & Carpus

A 35-year-old construction worker falls from a ladder and sustains a comminuted radial head fracture. During evaluation, he complains of wrist pain, and radiographs reveal positive ulnar variance and disruption of the distal radioulnar joint (DRUJ). He is diagnosed with an Essex-Lopresti injury. Which of the following surgical management strategies is most appropriate?

. Radial head excision and pinning of the DRUJ in supination
. Open reduction internal fixation of the radial head and immediate DRUJ motion
. Radial head arthroplasty and stabilization of the DRUJ
. Radial head excision with an ulnar shortening osteotomy
. Closed reduction of the DRUJ and casting in pronation

Correct Answer & Explanation

. Radial head arthroplasty and stabilization of the DRUJ

Explanation

An Essex-Lopresti injury consists of a radial head fracture, rupture of the interosseous membrane, and disruption of the DRUJ, leading to longitudinal radioulnar dissociation. Excision of the radial head without replacement is strictly contraindicated, as it will lead to rapid proximal migration of the radius and severe wrist and elbow dysfunction. Management requires restoring the lateral column of the elbow, typically with a radial head arthroplasty (since comminuted fractures are usually unfixable), followed by assessment and stabilization of the DRUJ (which may include TFCC repair and/or pinning the DRUJ in supination).

Question 386

Topic: Wrist & Carpus

A 45-year-old man presents with a sudden inability to flex the interphalangeal joint of his right thumb. He sustained a distal radius fracture 8 weeks ago that was treated with volar locked plating. Radiographs demonstrate the fracture is healing in good alignment, but the plate is positioned prominent and distal to the watershed line. Which of the following is the most likely etiology of his current deficit?

. Extensor pollicis longus rupture from dorsal screw protrusion
. Anterior interosseous nerve neuropraxia from localized edema
. Flexor pollicis longus rupture due to implant impingement
. Ischemic contracture of the thenar eminence
. Unrecognized associated scaphoid fracture with nonunion

Correct Answer & Explanation

. Flexor pollicis longus rupture due to implant impingement

Explanation

Volar plates placed distal to the watershed line of the distal radius can impinge on the flexor tendons. The flexor pollicis longus (FPL) tendon lies directly over the volar-ulnar aspect of the radius and is the most susceptible to attrition and rupture from prominent hardware. The patient's inability to actively flex the thumb interphalangeal joint is classic for an iatrogenic FPL rupture, which typically requires plate removal and tendon reconstruction (e.g., tendon transfer or graft).

Question 387

Topic: Wrist & Carpus

A 32-year-old male sustains a volar shear fracture of the distal radius (volar Barton fracture). During open reduction and internal fixation via a classic Henry approach, which of the following structures must be carefully protected to preserve the primary volar stabilizer of the radiocarpal joint?

. Radioscaphocapitate ligament
. Volar radioulnar ligament
. Lunotriquetral ligament
. Triangular fibrocartilage complex
. Dorsal radiocarpal ligament

Correct Answer & Explanation

. Radioscaphocapitate ligament

Explanation

The radioscaphocapitate (RSC) ligament is a critical volar stabilizer of the wrist, preventing ulnar translation of the carpus. During a volar approach to the distal radius (e.g., Henry approach), dissection distal to the watershed line must be minimized to avoid damaging the stout volar radiocarpal ligaments (RSC, long radiolunate, short radiolunate).

Question 388

Topic: Wrist & Carpus
A 39-year-old female presents with persistent ulnar-sided wrist pain that is exacerbated by gripping, pronation, and ulnar deviation. Conservative measures including splinting and NSAIDs have failed. Radiographs reveal 3.5 mm of positive ulnar variance. An MRI arthrogram demonstrates a degenerative, central perforation of the triangular fibrocartilage complex (TFCC) and corresponding chondromalacia on the proximal ulnar aspect of the lunate. What is the most appropriate surgical intervention?
. Arthroscopic primary TFCC repair to the fovea
. Ulnar shortening osteotomy
. Darrach procedure (distal ulnar resection)
. Sauvé-Kapandji procedure
. Proximal row carpectomy

Correct Answer & Explanation

. Ulnar shortening osteotomy

Explanation

This patient's presentation is classic for ulnar impaction syndrome with a Palmer Class 2C degenerative TFCC tear. The underlying biomechanical issue is excessive ulnar length (positive ulnar variance), leading to increased load transmission across the ulnocarpal joint. The most appropriate treatment for symptomatic ulnar impaction syndrome with ulnar variance >2 mm that has failed conservative care is an ulnar shortening osteotomy. This extra-articular procedure unloads the ulnocarpal joint and typically tightens the ulnocarpal ligaments. An arthroscopic wafer procedure may be considered if variance is <2 mm.

Question 389

Topic: Wrist & Carpus
A 28-year-old male sustains a scaphoid waist fracture that progresses to a scaphoid nonunion advanced collapse (SNAC) pattern. Radiographs reveal degenerative changes limited to the radioscaphoid joint. What stage of SNAC wrist does this represent?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage I

Explanation

SNAC Stage I involves arthritis localized to the radioscaphoid joint. Stage II involves the scaphocapitate joint, and Stage III progresses to involve the capitolunate joint.

Question 390

Topic: Wrist & Carpus

A 28-year-old construction worker complains of dorsal central wrist pain. Radiographs reveal ulnar negative variance and sclerosis of the lunate without collapse. MRI confirms diffuse avascular necrosis of the lunate. What is the most appropriate initial surgical intervention to offload the radiolunate joint?

. Ulnar lengthening osteotomy
. Proximal row carpectomy
. Radial shortening osteotomy
. Vascularized bone graft from the distal radius
. Lunate excision and silastic replacement

Correct Answer & Explanation

. Radial shortening osteotomy

Explanation

In early-stage Kienbock's disease (stage I or II) with ulnar negative variance, a radial shortening osteotomy is the treatment of choice. It levels the joint and decreases the mechanical load transmitted through the lunate, potentially allowing for revascularization.

Question 391

Topic: Wrist & Carpus

A 24-year-old gymnast presents with persistent ulnar-sided wrist pain and clicking upon pronation and supination. Examination reveals gross instability of the distal radioulnar joint (DRUJ) and a positive foveal sign. MRI confirms a complete avulsion of the triangular fibrocartilage complex (TFCC). Which specific fibers must be reattached to restore DRUJ stability?

. Superficial radioulnar ligaments attaching to the ulnar styloid tip
. Deep radioulnar ligaments (ligamentum subcruentum) attaching to the fovea
. Ulnocarpal ligaments (ulnolunate and ulnotriquetral)
. Extensor carpi ulnaris subsheath
. Volar radioulnar ligament midsubstance fibers

Correct Answer & Explanation

. Deep radioulnar ligaments (ligamentum subcruentum) attaching to the fovea

Explanation

The deep fibers of the TFCC (ligamentum subcruentum), which insert into the fovea at the base of the ulnar styloid, are the primary stabilizers of the DRUJ. Failure to repair these deep fibers results in persistent DRUJ instability.

Question 392

Topic: Wrist & Carpus
A 45-year-old man presents with chronic wrist pain. Radiographs demonstrate a chronic scaphoid nonunion with radioscaphoid arthritis, but the capitolunate joint and midcarpal joints are perfectly preserved. What stage of Scaphoid Nonunion Advanced Collapse (SNAC) does this represent, and what is an appropriate surgical option?
. Stage I SNAC; scaphoid excision and four-corner fusion
. Stage II SNAC; proximal row carpectomy
. Stage III SNAC; proximal row carpectomy
. Stage II SNAC; radial styloidectomy alone
. Stage I SNAC; total wrist arthrodesis

Correct Answer & Explanation

. Stage II SNAC; proximal row carpectomy

Explanation

SNAC Stage II involves arthritis extending to the entire radioscaphoid joint while sparing the midcarpal joint. Proximal row carpectomy (PRC) or scaphoid excision with four-corner fusion are standard motion-preserving surgical treatments for Stage II SNAC.

Question 393

Topic: Wrist & Carpus

A 62-year-old woman returns to the clinic 8 months after undergoing volar plate fixation for a distal radius fracture. She reports a sudden inability to actively flex the interphalangeal joint of her thumb. Radiographs reveal the hardware is intact but positioned distal to the watershed line. Which of the following is the most appropriate surgical management?

. Flexor carpi radialis (FCR) to flexor pollicis longus (FPL) tendon transfer
. Extensor indicis proprius (EIP) to FPL tendon transfer
. Primary end-to-end repair of the FPL tendon
. Free tendon graft using the palmaris longus
. Hardware removal and tenolysis only

Correct Answer & Explanation

. Extensor indicis proprius (EIP) to FPL tendon transfer

Explanation

Rupture of the FPL tendon post-volar plating is due to chronic attrition over the prominent plate and cannot be reliably repaired primarily. An EIP to FPL tendon transfer is the standard and most reliable method to restore thumb interphalangeal flexion.

Question 394

Topic: Wrist & Carpus

A 28-year-old man undergoes an open reduction and internal fixation of a distal radius fracture under regional anesthesia. During the administration of a supraclavicular brachial plexus block, the patient suddenly develops perioral numbness, tinnitus, and subsequent generalized seizures followed by ventricular arrhythmias. Which of the following local anesthetics was most likely used, given its high potential for irreversible cardiac toxicity?

. Lidocaine
. Ropivacaine
. Mepivacaine
. Bupivacaine
. Chloroprocaine

Correct Answer & Explanation

. Bupivacaine

Explanation

The clinical scenario describes Local Anesthetic Systemic Toxicity (LAST). Bupivacaine is a long-acting amide local anesthetic that is notoriously lipophilic and has a high affinity for cardiac voltage-gated sodium channels. If inadvertently injected intravascularly, it can cause severe, refractory cardiac arrhythmias (such as ventricular fibrillation) and cardiovascular collapse. Its cardiac toxicity is much more difficult to resuscitate (often requiring lipid emulsion therapy) compared to lidocaine. Ropivacaine was developed specifically as an alternative to bupivacaine because it is less lipophilic and has a significantly improved cardiac safety profile.

Question 395

Topic: Wrist & Carpus

A 22-year-old gymnast requires arthroscopic repair of a triangular fibrocartilage complex (TFCC) tear. Healing potential is closely related to the local vascularity. Which portion of the TFCC possesses the most robust blood supply?

. Central articular disc
. Radial attachment
. Peripheral 10-20% at the ulnar attachment
. Volar capsular margin only
. The entire structure is avascular

Correct Answer & Explanation

. Peripheral 10-20% at the ulnar attachment

Explanation

The TFCC receives its blood supply exclusively at its periphery, predominantly at the ulnar attachment (the peripheral 10-20%). The central portion is avascular and generally requires debridement rather than repair if torn.

Question 396

Topic: Wrist & Carpus

The Triangular Fibrocartilage Complex (TFCC) is the major stabilizer of the distal radioulnar joint (DRUJ). Which specific component of the TFCC provides the primary restraint to dorsal translation of the distal radius relative to the ulna during active forearm pronation?

. Volar radioulnar ligament
. Dorsal radioulnar ligament
. Ulnocarpal meniscus homologue
. Extensor carpi ulnaris (ECU) subsheath
. Ulnolunate ligament

Correct Answer & Explanation

. Dorsal radioulnar ligament

Explanation

The dorsal and volar radioulnar ligaments are the primary stabilizers of the DRUJ. During forearm pronation, the radius crosses over the ulna, and the dorsal radioulnar ligament stretches over the ulnar head and tightens. Thus, the dorsal radioulnar ligament prevents dorsal subluxation of the radius (or volar subluxation of the ulna) in pronation. Conversely, the volar radioulnar ligament tightens in supination.

Question 397

Topic: Wrist & Carpus

In a dorsal surgical approach to the distal radius, Lister's tubercle serves as a critical anatomical landmark. Which tendon utilizes this bony prominence as a mechanical pulley to change its line of pull?

. Extensor carpi radialis brevis
. Extensor pollicis longus
. Extensor digitorum communis
. Extensor carpi radialis longus
. Extensor indicis proprius

Correct Answer & Explanation

. Extensor pollicis longus

Explanation

The extensor pollicis longus (EPL) tendon resides in the third extensor compartment and turns sharply around the ulnar aspect of Lister's tubercle. This anatomical arrangement increases its risk for attrition and rupture following distal radius fractures.

Question 398

Topic: Wrist & Carpus

The central band of the interosseous membrane is critical for longitudinal radioulnar stability, particularly after a radial head excision. What is the anatomical orientation of the central band fibers?

. Proximal radius to distal ulna
. Proximal ulna to distal radius
. Transverse from radius to ulna
. Distal radius to proximal humerus
. Proximal radius to proximal ulna

Correct Answer & Explanation

. Proximal radius to distal ulna

Explanation

The central band of the interosseous membrane has strong fibers that run obliquely from proximal on the radius to distal on the ulna. This orientation effectively transfers axial compressive loads from the radius to the ulna.

Question 399

Topic: Wrist & Carpus

A 24-year-old gymnast sustains a traumatic tear of the triangular fibrocartilage complex (TFCC). Arthroscopy reveals a tear in the central articular disc. What is the healing potential of this specific region, and what is its vascular supply?

. High healing potential; supplied by the anterior interosseous artery
. Poor healing potential; avascular region
. High healing potential; supplied by the dorsal radiocarpal arch
. Poor healing potential; supplied by the ulnar artery
. Moderate healing potential; supplied by the palmar radiocarpal arch

Correct Answer & Explanation

. Poor healing potential; avascular region

Explanation

The central articular disc of the TFCC is avascular, receiving nutrients only through diffusion from synovial fluid. Consequently, tears in the central portion (Palmer 1A) have poor healing potential and are typically treated with debridement rather than repair.

Question 400

Topic: Wrist & Carpus

A 65-year-old woman is managed conservatively in a cast for a non-displaced distal radius fracture. Eight weeks later, she reports the sudden inability to actively extend her thumb interphalangeal joint. Rupture of which of the following tendons is the most likely cause?

. Extensor pollicis brevis
. Abductor pollicis longus
. Extensor pollicis longus
. Flexor pollicis longus
. Extensor indicis proprius

Correct Answer & Explanation

. Extensor pollicis longus

Explanation

Extensor pollicis longus (EPL) tendon rupture is a known complication of non-displaced distal radius fractures due to ischemia or mechanical attrition at the Lister tubercle. It presents with an inability to actively extend the thumb interphalangeal joint.

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