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Wrist & Carpus MCQs

Practice Set 9 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 161

Topic: Wrist & Carpus
A 70-year-old female presents with advanced Scapholunate Advanced Collapse (SLAC) wrist osteoarthritis. Which joint space is characteristically PRESERVED (spared from arthritic change) even in the late stages of this disease?
. Radioscaphoid joint
. Capitolunate joint
. Radiolunate joint
. Scaphotrapezial joint
. Lunotriquetral joint

Correct Answer & Explanation

. Radiolunate joint

Explanation

In both SLAC and SNAC (Scaphoid Nonunion Advanced Collapse) wrists, the radiolunate joint is characteristically spared from osteoarthritis. This is because the lunate has a spherical articulation with the lunate fossa of the radius, maintaining concentric loading without pathological shear forces, even when the scaphoid is destabilized. This preservation allows for salvage procedures like the four-corner fusion (capitate, hamate, lunate, triquetrum) combined with scaphoid excision.

Question 162

Topic: Wrist & Carpus

A patient undergoes open reduction and internal fixation of a Galeazzi fracture. Intraoperatively, after rigid anatomic fixation of the radius, the distal radioulnar joint (DRUJ) remains highly unstable in supination. What is the most appropriate intraoperative management of the DRUJ?

. Immobilization in pronation for 6 weeks
. Transfixing the DRUJ with K-wires in neutral rotation
. Transfixing the DRUJ with K-wires in supination
. Immediate Darrach procedure
. Ulnar shortening osteotomy

Correct Answer & Explanation

. Transfixing the DRUJ with K-wires in supination

Explanation

In a Galeazzi fracture, if the DRUJ remains grossly unstable after anatomic fixation of the radius, it should be pinned in the position of maximum stability to allow the ligaments to heal. This is typically achieved by transfixing the DRUJ with K-wires in supination for 4 to 6 weeks.

Question 163

Topic: Wrist & Carpus

A 55-year-old woman presents with the inability to flex her thumb interphalangeal joint 8 months after undergoing volar locking plate fixation for a distal radius fracture. Radiographs show a healed fracture but the plate is positioned anterior to the watershed line. Which of the following is the most likely cause of her current presentation?

. Attritional rupture of the flexor pollicis longus tendon
. Ischemic necrosis of the flexor pollicis longus muscle
. Iatrogenic injury to the anterior interosseous nerve
. Adhesive capsulitis of the thumb CMC joint
. Nonunion of the distal radius fracture

Correct Answer & Explanation

. Attritional rupture of the flexor pollicis longus tendon

Explanation

Volar plates placed distal to the watershed line of the distal radius can irritate and eventually cause attritional rupture of the flexor pollicis longus (FPL) tendon. This requires surgical intervention, often with tendon transfer or grafting.

Question 164

Topic: Wrist & Carpus

A 22-year-old athlete presents with a proximal pole scaphoid nonunion. MRI demonstrates avascular necrosis of the proximal pole. Which surgical approach and graft choice is most appropriate for this specific injury?

. Volar approach with non-vascularized iliac crest bone graft
. Dorsal approach with a 1,2-Intercompartmental Supraretinacular Artery (1,2-ICSRA) vascularized bone graft
. Volar approach with a free medial femoral condyle vascularized bone graft
. Dorsal approach with non-vascularized distal radius bone graft
. Volar approach with radial styloidectomy alone

Correct Answer & Explanation

. Dorsal approach with a 1,2-Intercompartmental Supraretinacular Artery (1,2-ICSRA) vascularized bone graft

Explanation

Proximal pole scaphoid fractures are best accessed via a dorsal approach. In the setting of avascular necrosis, a vascularized bone graft (such as the pedicled 1,2-ICSRA graft or a free medial femoral condyle graft) is indicated to promote healing.

Question 165

Topic: Wrist & Carpus
A 45-year-old manual laborer presents with chronic wrist pain and a history of an untreated scaphoid fracture years ago. Radiographs reveal a scaphoid nonunion with advanced radioscaphoid and capitolunate arthritis, but the radiolunate joint is well-preserved. Based on this specific pattern of arthritis (SNAC Stage III), which of the following is the most appropriate surgical treatment?
. Proximal row carpectomy (PRC)
. Scaphoid excision and four-corner fusion
. Total wrist arthrodesis
. Radial styloidectomy
. Distal radius osteotomy

Correct Answer & Explanation

. Scaphoid excision and four-corner fusion

Explanation

The patient has Scaphoid Nonunion Advanced Collapse (SNAC) Stage III, which involves arthritis of the radioscaphoid and capitolunate joints with sparing of the radiolunate joint. Proximal row carpectomy (PRC) is contraindicated because it relies on a pristine articulation between the capitate head and the lunate fossa, and the capitate is already arthritic here. Scaphoid excision and four-corner fusion (capitate, hamate, lunate, triquetrum) removes the arthritic joints while preserving the intact radiolunate joint, maintaining some wrist motion.

Question 166

Topic: Wrist & Carpus

During open reduction and internal fixation of a highly comminuted, intra-articular distal radius fracture utilizing a volar locking plate, the surgeon identifies a 'die-punch' fragment comprising the volar margin of the lunate fossa. Failure to adequately capture and buttress this specific fragment is most likely to result in:

. Extensor pollicis longus tendon rupture
. Flexor pollicis longus tendon rupture
. Dorsal radiocarpal dislocation
. Volar radiocarpal dislocation
. Scapholunate advanced collapse

Correct Answer & Explanation

. Volar radiocarpal dislocation

Explanation

The volar marginal fragment of the lunate fossa is a critical stabilizing structure of the radiocarpal joint because the short radiolunate ligament originates here. If this 'die-punch' fragment is not securely buttressed, the lunate (and subsequently the entire carpus) will follow the fragment, leading to a catastrophic volar subluxation or dislocation of the carpus.

Question 167

Topic: Wrist & Carpus

In Scapholunate Advanced Collapse (SLAC) of the wrist, progressive osteoarthritis occurs in a predictable pattern, typically advancing from the radioscaphoid joint to the capitolunate joint. Which biomechanical factor best explains why the radiolunate joint is consistently spared?

. The radiolunate ligaments undergo early pathological contracture.
. The capitate translates ulnarly, unloading the radiolunate joint.
. The lunate is devoid of hyaline cartilage on its proximal articular surface.
. The spherical congruency of the lunate fossa prevents pathological shear forces.
. The triangular fibrocartilage complex (TFCC) redistributes loads away from the lunate.

Correct Answer & Explanation

. The spherical congruency of the lunate fossa prevents pathological shear forces.

Explanation

In the SLAC wrist, the radioscaphoid joint degenerates first because the distal pole of the scaphoid rotates into flexion, creating incongruence and pathological shear stresses against the elliptical scaphoid fossa. In contrast, the lunate fossa of the distal radius and the proximal lunate are spherically congruent. Even when the lunate rotates into extension (DISI deformity), it remains concentrically loaded without abnormal shear forces, thereby preserving the radiolunate articular cartilage.

Question 168

Topic: Wrist & Carpus

In a volar Barton's fracture, the carpus typically subluxates volarly in conjunction with the volar marginal fracture fragment of the distal radius. Which of the following ligaments remains firmly attached to the lunate facet fragment, pulling the carpus volarly?

. Radioscaphocapitate ligament
. Short radiolunate ligament
. Long radiolunate ligament
. Scapholunate interosseous ligament
. Volar radioulnar ligament

Correct Answer & Explanation

. Short radiolunate ligament

Explanation

A volar Barton's fracture involves the volar lip of the distal radius lunate fossa. The short radiolunate ligament attaches firmly to this specific volar marginal fragment. When the fragment fractures and displaces volarly, the short radiolunate ligament pulls the lunate (and thus the rest of the carpus) along with it, causing the characteristic volar radiocarpal subluxation.

Question 169

Topic: Wrist & Carpus

A 32-year-old male sustains a distal radius fracture combined with a distal radioulnar joint (DRUJ) dislocation. Following anatomic reduction and fixation of the radius, the DRUJ remains grossly unstable in supination. The primary anatomical stabilizer of the DRUJ that is likely disrupted in this injury is the:

. Triangular Fibrocartilage Complex (TFCC)
. Extensor carpi ulnaris (ECU) subsheath
. Interosseous membrane
. Pronator quadratus muscle
. Volar radiocarpal ligament

Correct Answer & Explanation

. Triangular Fibrocartilage Complex (TFCC)

Explanation

The Triangular Fibrocartilage Complex (TFCC), specifically its deep dorsal and volar radioulnar ligaments (ligamentum subcruentum), is the primary stabilizer of the distal radioulnar joint (DRUJ). Disruption leads to gross DRUJ instability despite anatomic radius fixation.

Question 170

Topic: Wrist & Carpus

A 26-year-old man falls off a motorcycle and injures his left wrist. There are no open wounds and the neurovascular examination is normal. Radiographs

. closed reduction and casting.
. external fixation and percutaneous pinning of the distal radius.
. open reduction and internal fixation of the distal radius.
. open reduction and internal fixation of the distal radius and open repair of the ulnar styloid.
. nonbridging external fixation of the distal radius.

Correct Answer & Explanation

. open reduction and internal fixation of the distal radius.

Explanation

The patient has a high-energy injury with resultant comminution of the distal radius metaphysis. Cast immobilization is likely to lead to radial shortening and angulation due to the comminution. Similarly, while external fixation and pinning has been successful in the past, some loss of radial length and volar angulation is typically noted. Present plate fixation devices for the distal radius employing locking screw technology have a superior ability to resist radial shortening and dorsal angulation. Fixation of the ulnar styloid is warranted when there is distal radioulnar joint instability or significant displacement of the styloid. This is more likely to occur with a fracture at the base of the styloid. In this instance, the distal radioulnar joint does not appear to be disrupted.

Question 171

Topic: Wrist & Carpus

A patient is treated with volar plating for a distal radius fracture. The CT scan shown in Figure 15 is obtained after union of the fracture because the patient reports ongoing symptoms. The prominent hardware is most likely injuring what tendon?

Anatomy 2008 Practice Questions: Set 1 (Solved) - Figure 34

. Extensor pollicis brevis (EPB)
. Extensor carpi radialis brevis (ECRB)
. Extensor digitorum communis (EDC)
. Extensor carpi ulnaris (ECU)
. Extensor carpi radialis longus (ECRL)

Correct Answer & Explanation

. Extensor digitorum communis (EDC)

Explanation

Extensor tendon injuries have been reported after volar plating of distal radius fractures. The CT scan shows prominent dorsal hardware a few millimeters ulnar to Lister's tubercle. The second compartment, the ECRL and ECRB, is radial to Lister's tubercle. The ECU runs along the distal ulna. The contents of the fourth dorsal compartment run just ulnar to Lister's tubercle. The EDC tendon is likely irritated in this patient. The EPB runs along the radial border of the radius and is well away from prominent hardware. Benson EC, Decarvalho A, Mikola EA, et al: Two potential causes of EPL rupture after distal radius volar plate fixation. Clin Orthop Relat Res 2006;451:218-222.

Question 172

Topic: Wrist & Carpus

A 36-year-old woman is placed in a short arm cast for a nondisplaced extra-articular distal radius fracture. Seven weeks later she notes the sudden inability to extend her thumb. What is the most likely cause of her condition?

General Orthopedics Board Review 2026: High-Yield MCQs (Set 10) - Figure 82

. Posterior interosseous nerve palsy
. Cervical disk herniation
. Entrapment of the flexor pollicis longus tendon
. Rupture of the extensor pollicis longus tendon
. Metacarpophalangeal joint dislocation

Correct Answer & Explanation

. Rupture of the extensor pollicis longus tendon

Explanation

Detailed A recent review of 200 consecutive distal radius fractures noted that the overall incidence of extensor pollicis longus rupture was 3%. The causes are believed to be mechanical irritation, attrition, and vascular impairment. The fracture is usually nondisplaced and the patient notes weeks to months after injury the sudden, painless inability to extend the thumb. Treatment involves extensor indicis proprius tendon transfer or free palmaris longus tendon grafting. Skoff HD: Postfracture extensor pollicis longus tenosynovitis and tendon rupture: A scientific study and personal series. Am J Orthop 2003;32:245-247. Bonatz E, Kramer TD, Masear VR: Rupture of the extensor pollicis longus tendon. Am J Orthop 1996;25:118-122.

Question 173

Topic: Wrist & Carpus

A 62-year-old female is 6 months post-operative from a volar locked plating of a comminuted distal radius fracture. She presents to the clinic complaining of a new inability to actively flex the interphalangeal (IP) joint of her thumb. Passive IP flexion is intact. Which of the following technical errors during the initial surgery is most likely responsible for this complication?

. Placement of the volar plate distal to the watershed line
. Use of excessively long dorsal screws irritating the extensor pollicis longus (EPL)
. Iatrogenic traction injury to the median nerve during the modified Henry approach
. Failure to repair the pronator quadratus during closure
. Prominent hardware violating the distal radioulnar joint (DRUJ)

Correct Answer & Explanation

. Placement of the volar plate distal to the watershed line

Explanation

Loss of active thumb IP joint flexion after volar distal radius plating points to an attritional rupture of the Flexor Pollicis Longus (FPL) tendon. The most common iatrogenic cause of FPL rupture in this setting is the placement of the volar plate distal to the 'watershed line' of the distal radius. This prominence acts as a mechanical fulcrum, causing friction, fraying, and eventual attritional rupture of the FPL.

Question 174

Topic: Wrist & Carpus



A 41-year-old female develops a widespread eczematous skin rash overlying her forearm three weeks after open reduction and internal fixation of a distal radius fracture utilizing a standard 316L stainless steel volar locking plate. Dermatology consultation confirms a metal allergy via patch testing. Which specific element within the stainless steel alloy is most commonly responsible for this type IV hypersensitivity reaction?

. Titanium
. Cobalt
. Chromium
. Nickel
. Molybdenum

Correct Answer & Explanation

. Nickel

Explanation

Nickel is the most common metal sensitizer in the general population, accounting for the vast majority of Type IV hypersensitivity (allergic contact dermatitis) reactions to metallic orthopedic implants. Medical-grade 316L stainless steel contains approximately 10-14% nickel, making it a frequent culprit in sensitive individuals, often necessitating hardware removal or revision to a titanium implant.

Question 175

Topic: Wrist & Carpus

A 60-year-old female undergoes volar locked plating for a displaced distal radius fracture. Eight weeks post-operatively, she returns complaining of the sudden inability to actively flex the interphalangeal joint of her thumb. Which of the following surgical errors most likely led to this complication?

. Plate placed distal to the watershed line
. Dorsal screw penetration
. Unrecognized scapholunate ligament tear
. Failure to repair the pronator quadratus
. Over-distraction of the radiocarpal joint

Correct Answer & Explanation

. Plate placed distal to the watershed line

Explanation

Flexor pollicis longus (FPL) tendon rupture is a known complication of volar plating of the distal radius. It is typically caused by placement of the plate distal to the watershed line, allowing the FPL tendon to rub against the prominent distal edge of the plate.

Question 176

Topic: Wrist & Carpus
A 45-year-old manual laborer presents with chronic right wrist pain. He recalls a severe sprain 10 years ago that was untreated. Radiographs demonstrate an established scaphoid nonunion with arthritic changes at the radioscaphoid and capitolunate joints, but preservation of the radiolunate articulation. Based on the expected stage of this disease process, which of the following is the most appropriate surgical treatment?
. Open reduction internal fixation of the scaphoid with vascularized bone graft
. Radial styloidectomy alone
. Proximal row carpectomy (PRC)
. Total wrist arthroplasty
. Scaphotrapeziotrapezoid (STT) fusion

Correct Answer & Explanation

. Proximal row carpectomy (PRC)

Explanation

This patient has Scaphoid Nonunion Advanced Collapse (SNAC) Stage III, defined by arthritis at both the radioscaphoid joint and the midcarpal (capitolunate) joint, with a preserved radiolunate joint. Open reduction and internal fixation is no longer indicated once degenerative changes have occurred. Radial styloidectomy is insufficient for Stage III. The standard salvage procedures for SNAC Stage III (and SLAC Stage III) are either a proximal row carpectomy (PRC) or a scaphoid excision with a four-corner fusion. The radiolunate fossa is typically spared in both SLAC and SNAC wrists because the lunate maintains a concentric articulation with the radius.

Question 177

Topic: Wrist & Carpus

A 72-year-old female sustains a distal radius fracture.

She undergoes volar locking plate fixation. Three months postoperatively, she suddenly cannot flex the interphalangeal joint of her thumb. Which tendon is most likely injured?

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

Correct Answer & Explanation

. Flexor pollicis longus

Explanation

Attrition rupture of the Flexor Pollicis Longus (FPL) tendon is a known complication of volar plating of the distal radius. It typically occurs due to plate prominence distal to the watershed line, which leads to friction against the FPL tendon during thumb motion.

Question 178

Topic: Wrist & Carpus

A 60-year-old female presents with sudden inability to actively flex the interphalangeal (IP) joint of her thumb. She underwent open reduction and internal fixation of a distal radius fracture with a volar locking plate 8 months ago. Radiographs show the plate is well-fixed but positioned distally on the radius. What anatomical landmark was most likely violated, leading to this specific complication?

. The sigmoid notch
. Lister's tubercle
. The watershed line
. The pronator quadratus insertion
. The radial styloid groove

Correct Answer & Explanation

. The watershed line

Explanation

This patient has suffered a rupture of the Flexor Pollicis Longus (FPL) tendon, which is the most common tendon rupture following volar plate fixation of the distal radius. The primary risk factor is placing the plate distal to the 'watershed line' (the bony ridge at the distal margin of the pronator fossa). When the plate sits anterior to this line, it acts as a prominent friction point against the flexor tendons, particularly the FPL, leading to attritional wear and delayed rupture.

Question 179

Topic: Wrist & Carpus

A 60-year-old woman presents 4 weeks after sustaining a nondisplaced distal radius fracture, which was managed in a short arm cast. She now complains of a sudden inability to actively extend the interphalangeal joint of her thumb. Which of the following represents the most likely etiology of this complication?

. Injury to the posterior interosseous nerve
. Attritional rupture of the extensor pollicis longus tendon over Lister's tubercle
. Volar subluxation of the distal radioulnar joint
. Adhesion of the flexor pollicis longus tendon
. Ischemic contracture of the forearm musculature

Correct Answer & Explanation

. Attritional rupture of the extensor pollicis longus tendon over Lister's tubercle

Explanation

Extensor pollicis longus (EPL) tendon rupture is a known complication following distal radius fractures, peculiarly most often associated with non-displaced or minimally displaced fractures. It occurs due to attritional wear as the tendon glides over the fracture callus near Lister's tubercle, combined with focal ischemia within the third dorsal compartment. The classic presentation is a sudden inability to extend the IP joint of the thumb a few weeks post-injury. Treatment is typically an extensor indicis proprius (EIP) to EPL tendon transfer.

Question 180

Topic: Wrist & Carpus
A 45-year-old manual laborer presents with chronic wrist pain and stiffness. Radiographs demonstrate Scaphoid Nonunion Advanced Collapse (SNAC) Stage III. Which of the following joint involvement patterns correctly describes SNAC Stage III, making Proximal Row Carpectomy (PRC) contraindicated?
. Isolated radioscaphoid arthritis
. Capitolunate arthritis
. Scaphocapitate arthritis
. Pancarpal arthritis
. Radiolunate arthritis

Correct Answer & Explanation

. Capitolunate arthritis

Explanation

SNAC staging progresses as follows: Stage I involves the radioscaphoid joint (specifically the radial styloid); Stage II involves the scaphocapitate joint; Stage III involves the capitolunate joint; and Stage IV is pancarpal arthritis. Proximal row carpectomy (PRC) relies on a preserved proximal capitate head articulating with the lunate fossa of the radius. Because SNAC III involves degenerative changes at the capitolunate joint (including the capitate head), PRC is contraindicated, and a four-corner arthrodesis is the preferred motion-preserving salvage procedure.

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