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7. Hand and Wrist MCQs

Practice Set 180 of 266

This practice set contains high-yield board review questions covering key concepts in 7. Hand and Wrist. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 3581

Topic: 7. Hand and Wrist

A patient with a perilunate dislocation is successfully reduced and stabilized. Which of the following is an expected post-operative limitation or complication, even with optimal management?

. Complete restoration of wrist motion and strength within 3 months
. Zero risk of future wrist osteoarthritis
. Permanent median nerve palsy
. Some degree of persistent stiffness and reduced grip strength
. Immediate return to full strenuous activities

Correct Answer & Explanation

. Some degree of persistent stiffness and reduced grip strength

Explanation

Even with successful reduction and optimal surgical management, perilunate dislocations are severe injuries. Patients often experience some degree of persistent wrist stiffness, reduced range of motion, and decreased grip strength in the long term. While excellent results can be achieved, complete restoration of pre-injury function is rare. The risk of future wrist osteoarthritis remains high due to articular cartilage damage and altered carpal mechanics. Permanent median nerve palsy is a complication if not addressed, but not anexpectedoutcome with optimal care. Immediate return to activities is unrealistic.

Question 3582

Topic: 7. Hand and Wrist

What is the preferred method for assessing the alignment and stability of the scaphoid and lunate post-operatively, particularly regarding dynamic instability?

. Static PA and lateral radiographs
. Stress radiographs (e.g., clenched-fist PA view)
. Electromyography (EMG)
. Ultrasound imaging
. Bone scan

Correct Answer & Explanation

. Stress radiographs (e.g., clenched-fist PA view)

Explanation

While static PA and lateral radiographs are standard, stress radiographs, particularly a clenched-fist PA view, are often used to dynamically assess scapholunate stability post-operatively or in cases of suspected instability. This view can exaggerate any widening of the scapholunate interval (Terry Thomas sign) if instability persists. EMG is for nerve function, ultrasound has limited utility for deep carpal instability, and bone scan is for metabolic activity or inflammation. CT/MRI can assess static alignment and ligament integrity but not dynamic instability as effectively as stress radiographs.

Question 3583

Topic: 7. Hand and Wrist

Which muscle tendon is typically retracted dorsally to gain access to the dorsal wrist capsule during a dorsal approach for perilunate dislocation repair?

. Flexor carpi radialis
. Extensor carpi ulnaris
. Extensor pollicis longus
. Abductor pollicis longus
. Flexor digitorum superficialis

Correct Answer & Explanation

. Extensor pollicis longus

Explanation

In a dorsal approach to the wrist for perilunate dislocation, the interval between the third (extensor pollicis longus) and fourth (extensor digitorum communis and indicis proprius) extensor compartments is commonly utilized. The extensor pollicis longus (EPL) tendon (within the 3rd compartment) is typically retracted radially, and the common digital extensors (within the 4th compartment) are retracted ulnarly, or the fourth compartment is incised and its contents retracted. The EPL is the muscle most commonly identified and retracted to define this interval for exposing the dorsal wrist capsule.

Question 3584

Topic: 7. Hand and Wrist

The concept of 'lesser arc injury' versus 'greater arc injury' in carpal trauma refers to:

. The size of the carpal bones involved
. The extent of soft tissue versus bone involvement
. Whether the injury involves the distal or proximal carpal row
. Whether the injury path includes intra-carpal fractures (greater arc) or only ligamentous disruptions (lesser arc)
. The age of the patient

Correct Answer & Explanation

. Whether the injury path includes intra-carpal fractures (greater arc) or only ligamentous disruptions (lesser arc)

Explanation

The 'greater arc' of the carpus refers to the bony structures that form the periphery (scaphoid, trapezium, trapezoid, capitate, hamate, triquetrum). A 'greater arc injury' typically involves carpal bone fractures (e.g., trans-scaphoid, trans-capitate, trans-triquetral) in addition to ligamentous disruption. The 'lesser arc' refers to the intrinsic intercarpal ligaments (scapholunate, lunotriquetral). A 'lesser arc injury' involves only ligamentous disruption without carpal fractures, which is less common in severe dislocations. Thus, it's about whether the injury path includes fractures or just ligaments around the lunate.

Question 3585

Topic: 7. Hand and Wrist

A patient has a chronic perilunate dislocation with significant degenerative changes noted on radiographs, including radioscaphoid arthritis and collapse. The lunate fossa of the radius appears relatively preserved. Which salvage procedure might be considered?

. Wrist arthroscopy and debridement
. Isolated scaphotrapeziotrapezoid (STT) fusion
. Proximal row carpectomy (PRC)
. Total wrist arthroplasty
. Four-corner fusion

Correct Answer & Explanation

. Proximal row carpectomy (PRC)

Explanation

For chronic perilunate dislocations with established degenerative changes, especially radioscaphoid arthritis, but with a preserved lunate fossa, a Proximal Row Carpectomy (PRC) can be a viable salvage option. PRC involves excising the scaphoid, lunate, and triquetrum, allowing the capitate to articulate directly with the lunate fossa of the radius. This provides pain relief and preserves a good range of motion, provided the capitate head and lunate fossa are healthy. Four-corner fusion (fusion of capitate, hamate, triquetrum, lunate) is an alternative but also involves removing the scaphoid, leaving the lunate, and fusing it to other carpals – it leads to less motion than PRC but can be more stable. Total wrist arthroplasty is generally reserved for inflammatory arthritis or very low demand patients. Arthroscopy and STT fusion are not appropriate for advanced degenerative changes from a perilunate dislocation.

Question 3586

Topic: 7. Hand and Wrist

A 50-year-old male with an acute perilunate dislocation reports a 'pop' in his wrist. Which of the following findings on physical examination, in addition to pain and swelling, would be most concerning for a potential complication requiring immediate intervention?

. Ecchymosis around the wrist
. Palpable bony tenderness
. Intact capillary refill in the fingers
. Loss of sensation in the thumb, index, and middle fingers
. Mild reduction in wrist range of motion

Correct Answer & Explanation

. Loss of sensation in the thumb, index, and middle fingers

Explanation

Loss of sensation in the thumb, index, and middle fingers (median nerve distribution) is a critical finding indicating significant median nerve compression. This complication can lead to permanent nerve damage if not promptly addressed by reduction (and surgical decompression if symptoms persist after reduction). While the other findings are expected with a severe wrist injury, median nerve compromise carries the highest risk of immediate long-term morbidity and dictates urgent management. Intact capillary refill is a positive sign, indicating adequate perfusion, not a concern.

Question 3587

Topic: 7. Hand and Wrist

Which of the following statements regarding the stability of a reduced perilunate dislocation is MOST accurate?

. Closed reduction alone is always sufficient for long-term stability.
. Ligament healing typically restores 100% of pre-injury strength.
. The carpus remains inherently unstable after reduction due to extensive ligamentous damage, often requiring surgical stabilization.
. Physiotherapy alone can fully compensate for ligamentous disruption.
. The risk of redislocation is negligible after initial reduction.

Correct Answer & Explanation

. The carpus remains inherently unstable after reduction due to extensive ligamentous damage, often requiring surgical stabilization.

Explanation

Perilunate dislocations involve extensive disruption of the intrinsic and extrinsic carpal ligaments. Even after successful closed reduction, the carpus remains inherently unstable due to this significant ligamentous damage. This instability often necessitates surgical stabilization (e.g., K-wire fixation and ligament repair/reconstruction) to maintain anatomical alignment and allow for proper ligamentous healing. Closed reduction alone typically leads to redislocation or chronic instability, and physiotherapy cannot compensate for the structural loss.

Question 3588

Topic: 7. Hand and Wrist

What imaging modality is most sensitive for assessing the integrity of the scapholunate interosseous ligament and detecting subtle carpal instability patterns after reduction?

. Plain radiographs (PA and lateral)
. Computed Tomography (CT)
. Magnetic Resonance Imaging (MRI) with or without arthrography
. Ultrasound
. Bone scintigraphy

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI) with or without arthrography

Explanation

Magnetic Resonance Imaging (MRI), especially with arthrography (MRA), is the most sensitive imaging modality for directly visualizing and assessing the integrity of the intrinsic carpal ligaments, such as the scapholunate interosseous ligament. It can detect subtle tears and provide detailed information about soft tissue injury and early degenerative changes not visible on plain radiographs or CT. CT is excellent for bony detail and alignment, but less sensitive for ligaments. Ultrasound and bone scintigraphy have limited roles in this specific assessment.

Question 3589

Topic: 7. Hand and Wrist

Which of the following is considered a relative contraindication to attempting closed reduction of an acute perilunate dislocation?

. Presence of a median nerve palsy
. Significant wrist swelling
. Patient age over 60
. Open fracture or significant skin compromise
. Associated undisplaced radial styloid fracture

Correct Answer & Explanation

. Open fracture or significant skin compromise

Explanation

An open fracture or significant skin compromise overlying the wrist joint is a relative contraindication to closed reduction attempts, especially if it could convert a closed injury to an open one through excessive manipulation, or if there's a risk of introducing infection. While median nerve palsy and swelling are common, they are indications forurgentreduction rather than contraindications. Older age or an associated undisplaced radial styloid fracture do not preclude careful closed reduction.

Question 3590

Topic: 7. Hand and Wrist

What is the primary vector of force leading to a perilunate dislocation according to biomechanical studies?

. Direct blow to the dorsal wrist
. Axial compression with the wrist in flexion
. Hyperextension, ulnar deviation, and intercarpal supination
. Radial deviation with pronation
. Repetitive stress injury

Correct Answer & Explanation

. Hyperextension, ulnar deviation, and intercarpal supination

Explanation

The typical mechanism of injury for a perilunate dislocation involves a fall onto an outstretched hand (FOOSH) with the wrist in forced hyperextension, ulnar deviation, and often an element of intercarpal supination. This combination of forces causes the carpus to dorsally 'peel off' the lunate, leading to the progressive ligamentous disruption characteristic of a perilunate injury. Other force vectors are less common for this specific injury pattern.

Question 3591

Topic: Wrist & Carpus

In the context of perilunate instability, what is the significance of the 'ring sign' on a PA wrist radiograph?

. It indicates avascular necrosis of the lunate.
. It signifies an associated scaphoid fracture.
. It suggests rotary subluxation of the scaphoid due to scapholunate dissociation.
. It demonstrates widening of the lunotriquetral interval.
. It represents a fracture of the triquetrum.

Correct Answer & Explanation

. It suggests rotary subluxation of the scaphoid due to scapholunate dissociation.

Explanation

The 'ring sign' (or 'signet ring sign') is seen on a PA radiograph when the scaphoid bone is rotated into flexion. This flexion creates a superimposition of its distal pole on its body, making the distal pole appear as a dense ring. This sign is indicative of rotary subluxation of the scaphoid, which occurs due to disruption of the scapholunate interosseous ligament, a key component of perilunate instability. It does not directly indicate AVN, scaphoid fracture (though often co-occurs), lunotriquetral widening, or triquetral fracture.

Question 3592

Topic: 7. Hand and Wrist

When performing open reduction and internal fixation for a perilunate dislocation, after reducing the carpus, which anatomical structure is most commonly targeted for primary repair or augmentation to restore dorsal carpal stability?

. Volar radioscaphocapitate ligament
. Transverse carpal ligament
. Dorsal radiocarpal ligaments (specifically the dorsal intercarpal ligament and dorsal scapholunate ligament)
. Triangular fibrocartilage complex (TFCC)
. Flexor retinaculum

Correct Answer & Explanation

. Dorsal radiocarpal ligaments (specifically the dorsal intercarpal ligament and dorsal scapholunate ligament)

Explanation

While volar ligaments are often ruptured, the dorsal approach allows for direct repair of the dorsal radiocarpal ligaments, particularly the dorsal intercarpal ligament and the dorsal scapholunate ligament. These ligaments are crucial for dorsal carpal stability and are typically extensively disrupted in perilunate dislocations. Their repair or augmentation, along with K-wire stabilization, is essential to prevent recurrent dorsal subluxation. The TFCC primarily stabilizes the DRUJ. Volar ligaments are also important but typically addressed via a separate volar approach or indirectly.

Question 3593

Topic: 7. Hand and Wrist

Post-operatively, what is the recommended position for wrist immobilization after surgical repair of a perilunate dislocation?

. Full wrist extension and ulnar deviation
. Mild wrist flexion and radial deviation
. Neutral wrist position with slight ulnar deviation
. Full wrist flexion and pronation
. Full wrist extension and supination

Correct Answer & Explanation

. Neutral wrist position with slight ulnar deviation

Explanation

Following surgical repair of a perilunate dislocation, the wrist is typically immobilized in a neutral position or slight flexion (around 10-20 degrees) and slight ulnar deviation. This position helps to maintain the reduction, reduce tension on the repaired dorsal ligaments, and keep the scaphoid in a more favorable position for healing, minimizing the tendency for scaphoid flexion. Extreme positions should be avoided.

Question 3594

Topic: Wrist & Carpus

What factor is most strongly associated with a higher likelihood of failure following surgical repair of perilunate dislocations?

. Patient age under 30
. Acute presentation (within 24 hours)
. Delay in surgical intervention beyond 6 weeks
. Absence of associated scaphoid fracture
. Use of K-wire stabilization

Correct Answer & Explanation

. Delay in surgical intervention beyond 6 weeks

Explanation

Delay in surgical intervention, particularly beyond 6 weeks (often considered chronic), is strongly associated with a higher likelihood of surgical failure, residual pain, stiffness, and the development of degenerative arthritis. With chronicity, soft tissues contract, articular cartilage may be damaged, and reduction becomes more challenging, often requiring salvage procedures rather than primary repair. Acute presentation and K-wire stabilization improve outcomes, and patient age or absence of scaphoid fracture are less dominant factors for failure compared to chronicity.

Question 3595

Topic: Wrist & Carpus

Which of the following describes the anatomical defect in a 'trans-radial styloid perilunate dislocation'?

. A dislocation where the lunate is fractured.
. A perilunate dislocation associated with a fracture of the radial styloid process.
. A dislocation involving the distal radioulnar joint.
. A fracture of the capitate with perilunate instability.
. A dislocation where the scaphoid is excluded from the injury.

Correct Answer & Explanation

. A perilunate dislocation associated with a fracture of the radial styloid process.

Explanation

A 'trans-radial styloid perilunate dislocation' refers to a perilunate dislocation that is associated with a fracture of the radial styloid process. The force vector typically involves a radial component, causing the radial styloid to avulse or fracture as the carpus displaces. This is a common associated bony injury and falls under the 'greater arc' injury pattern when combined with the ligamentous disruption.

Question 3596

Topic: 7. Hand and Wrist

In the classification of carpal instability, what does the acronym 'DISI' stand for?

. Dorsal Intercalated Scapholunate Instability
. Distal Intercarpal Segmental Instability
. Dorsal Intercalated Segmental Instability
. Dynamic Intercarpal Scaphoid Impaction
. Dislocated Intrinsic Scapholunate Impairment

Correct Answer & Explanation

. Dorsal Intercalated Segmental Instability

Explanation

DISI stands for Dorsal Intercalated Segmental Instability. It is a common pattern of carpal collapse seen after scapholunate ligament injury, where the scaphoid flexes volarly, and the lunate extends dorsally, causing the lunate to appear dorsally tilted on a lateral radiograph. The opposing pattern, VISI (Volar Intercalated Segmental Instability), is caused by lunotriquetral ligament injury.

Question 3597

Topic: 7. Hand and Wrist

What is the typical management for a perilunate dislocation in a young, active patient presenting acutely (within hours to days) without significant associated fractures or neurovascular compromise?

. Closed reduction and long-term cast immobilization only
. Immediate volar carpal tunnel release
. Open reduction and internal fixation (ORIF) with ligament repair/reconstruction
. Observation with progressive range of motion exercises
. Total wrist fusion

Correct Answer & Explanation

. Open reduction and internal fixation (ORIF) with ligament repair/reconstruction

Explanation

For young, active patients with acute perilunate dislocations, particularly when there is no significant neurovascular compromise after initial reduction, open reduction and internal fixation (ORIF) with primary ligament repair and K-wire stabilization is the preferred definitive treatment. This approach aims to restore anatomical alignment, reconstruct or repair the torn ligaments, and prevent long-term instability and osteoarthritis. While closed reduction is an urgent first step, it is rarely definitive for long-term stability due to the extensive ligamentous damage. Other options are either inadequate or too extreme for an acute presentation.

Question 3598

Topic: 7. Hand and Wrist
Which structure contributes significantly to the blood supply of the lunate and is at risk during severe lunate displacement or manipulation?
. Deep palmar arch
. Superficial palmar arch
. Volar and dorsal branches of the radial and ulnar arteries supplying the lunate via its capsule
. Anterior interosseous artery
. Posterior interosseous artery

Correct Answer & Explanation

. Volar and dorsal branches of the radial and ulnar arteries supplying the lunate via its capsule

Explanation

The blood supply to the lunate arises primarily from small intraosseous vessels that enter through its volar and dorsal capsules, fed by branches of the radial and ulnar arteries. These capsular attachments are often disrupted during severe dislocations, increasing the risk of avascular necrosis.

Question 3599

Topic: 7. Hand and Wrist

A patient is undergoing open reduction for a chronic perilunate dislocation. The surgeon observes significant contracture of the dorsal wrist capsule and ligaments. What intraoperative maneuver might be necessary to achieve reduction?

. Dorsal capsulodesis
. Volar capsular release
. Distraction osteogenesis of the radius
. Proximal row carpectomy
. Excision of the radial styloid

Correct Answer & Explanation

. Volar capsular release

Explanation

In chronic perilunate dislocations, contracture of the volar wrist capsule and ligaments is a common impediment to reduction, especially of the dorsally displaced carpus. A volar capsular release, typically through a separate volar incision, may be necessary to allow the carpus to be reduced volarly and regain its articulation with the lunate. Dorsal capsulodesis is a stabilization procedure, not a release to aid reduction. Distraction osteogenesis or excisions are typically not needed to simply achieve reduction unless part of a salvage procedure. Proximal row carpectomy is a salvage, not a reduction, procedure.

Question 3600

Topic: 7. Hand and Wrist

In a complete lunate dislocation (Stage IV Mayfield), the lunate typically displaces in which direction?

. Dorsally
. Radially
. Ulnarly
. Volarly (into the carpal tunnel)
. Proximally

Correct Answer & Explanation

. Volarly (into the carpal tunnel)

Explanation

In a complete lunate dislocation (Mayfield Stage IV), the lunate itself dislocates volarly into the carpal tunnel, typically after the entire carpus has dislocated dorsally and then the lunate is 'pushed out' volarly. This is often associated with significant median nerve compression. Perilunate dislocation is when the carpus dislocates dorsallyaroundthe lunate, which maintains its radiolunate articulation.

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