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Wrist & Carpus MCQs

Practice Set 23 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 441

Topic: Wrist & Carpus

What is the typical timeframe within which closed reduction and percutaneous pinning are most likely to be successful for a lunate or perilunate dislocation?

. Within 24 hours of injury
. Within 1 week of injury
. Within 3 weeks of injury
. Within 6 weeks of injury
. Anytime within 6 months of injury

Correct Answer & Explanation

. Within 1 week of injury

Explanation

Closed reduction and percutaneous pinning are generally most successful if performed within 1 week of injury. Beyond this timeframe, soft tissue swelling, adhesions, and muscle spasm make closed reduction increasingly difficult, and the chances of successful anatomical reduction diminish significantly, often necessitating open reduction. While 24 hours is ideal, up to a week is generally considered the window for attempts at closed reduction before considering open options.

Question 442

Topic: Wrist & Carpus

Which of the following associated injuries is most frequently found in conjunction with a perilunate dislocation, particularly in high-energy trauma?

. Distal radius fracture
. Metacarpal fracture
. Scaphoid fracture
. Ulnar styloid fracture
. Phalangeal fracture

Correct Answer & Explanation

. Scaphoid fracture

Explanation

A scaphoid fracture is the most common associated bony injury with perilunate dislocations, leading to a 'trans-scaphoid perilunate dislocation'. This injury occurs when the force of the dislocation propagates through the scaphoid bone instead of rupturing the scapholunate ligament alone. It's important to specifically look for this given its high incidence and implications for treatment.

Question 443

Topic: Wrist & Carpus

Which of the following factors significantly increases the likelihood of a lunate dislocation requiring open reduction and internal fixation rather than successful closed reduction?

. Patient age under 30 years
. Injury sustained in a low-energy mechanism
. Presentation to the emergency department within 6 hours of injury
. Associated scaphoid fracture (trans-scaphoid perilunate dislocation)
. Absence of median nerve symptoms

Correct Answer & Explanation

. Associated scaphoid fracture (trans-scaphoid perilunate dislocation)

Explanation

An associated scaphoid fracture (trans-scaphoid perilunate dislocation) significantly complicates closed reduction. The presence of a fracture fragment prevents smooth reduction and often requires open reduction to stabilize the fracture and repair associated ligaments, even if initial closed reduction of the dislocation seems possible. The other options generally favor successful closed reduction or are less of a contraindication to closed reduction attempts.

Question 444

Topic: Wrist & Carpus

When evaluating a lateral wrist radiograph, what normal alignment feature, when disrupted, suggests a perilunate or lunate dislocation?

. The normal alignment of the radial styloid with the scaphoid
. The articulation of the pisiform with the triquetrum
. The 'three-arc' alignment of Gilula's lines
. The collinear relationship of the radius, lunate, and capitate
. The normal ulnar variance

Correct Answer & Explanation

. The collinear relationship of the radius, lunate, and capitate

Explanation

On a true lateral wrist radiograph, the radius, lunate, and capitate should appear collinear, forming a continuous 'column.' Disruption of this collinear relationship, particularly the lunate displacing volarly or the capitate displacing dorsally relative to the lunate, is a hallmark of lunate or perilunate dislocations. Gilula's lines are assessed on an AP view to evaluate carpal alignment. Radial styloid-scaphoid articulation and pisiform-triquetrum articulation are important but not the primary indicator on a lateral for this specific injury. Ulnar variance relates to distal radius and ulna length.

Question 445

Topic: Wrist & Carpus

A 28-year-old male sustains a dorsal perilunate dislocation. After successful closed reduction, what is the next most critical step in management to ensure optimal outcome and prevent recurrence?

. Immediate full range of motion exercises
. Application of a short arm cast for 2 weeks
. Referral for occupational therapy for desensitization
. Surgical stabilization with K-wires and ligament repair (ORIF)
. Prescription of NSAIDs and activity modification

Correct Answer & Explanation

. Surgical stabilization with K-wires and ligament repair (ORIF)

Explanation

Dorsal perilunate dislocations, even if successfully reduced closed, are highly unstable due to extensive ligamentous disruption. The next critical step is almost always surgical stabilization with K-wires and ligament repair (ORIF) to maintain the reduction and allow for proper ligamentous healing. Without surgical stabilization, the risk of redislocation and chronic instability (leading to SLAC wrist) is very high. Immediate motion is contraindicated. A short arm cast alone is insufficient for stabilization of such an unstable injury.

Question 446

Topic: Wrist & Carpus

Which type of carpal instability is characterized by a volar tilt of the lunate on a lateral radiograph and is typically associated with a lunotriquetral ligament injury?

. DISI (Dorsal Intercalated Segmental Instability)
. VISI (Volar Intercalated Segmental Instability)
. SNAC (Scaphoid Nonunion Advanced Collapse)
. SLAC (Scapholunate Advanced Collapse)
. Radial intercalated segmental instability

Correct Answer & Explanation

. VISI (Volar Intercalated Segmental Instability)

Explanation

VISI (Volar Intercalated Segmental Instability) is characterized by a volar tilt or flexion of the lunate on a lateral radiograph. This pattern is typically associated with disruption of the lunotriquetral interosseous ligament (LTIL). DISI is a dorsal tilt of the lunate, associated with SLIL injury. SNAC and SLAC are patterns of degenerative arthritis. Radial intercalated segmental instability is not a recognized term.

Question 447

Topic: Wrist & Carpus

What anatomical structure provides the most substantial extrinsic volar support to the lunate, often injured in lunate dislocations?

. Dorsal radiocarpal ligament
. Radioscaphocapitate ligament
. Ulnolunate ligament
. Triangular fibrocartilage complex (TFCC)
. Extensor carpi ulnaris tendon

Correct Answer & Explanation

. Radioscaphocapitate ligament

Explanation

The radioscaphocapitate ligament (also known as the 'long radiolunate ligament' or 'arcuate ligament') is a strong extrinsic volar ligament that originates from the radius and inserts onto the scaphoid, capitate, and lunate. It is a critical stabilizer of the scaphoid and lunate and is frequently torn in perilunate and lunate dislocations. The dorsal radiocarpal ligament is dorsal. The ulnolunate ligament is on the ulnar side. The TFCC stabilizes the DRUJ and ulnar carpus. The ECU tendon is an extrinsic muscle tendon.

Question 448

Topic: Wrist & Carpus

Which surgical technique for lunate or perilunate dislocation repair involves advancing a portion of the dorsal radiocarpal ligament to augment the repair of the scapholunate ligament?

. Rappaport procedure
. Brunelli procedure
. Blatt capsulodesis (dorsal capsulodesis)
. Ramon's tenodesis
. Watson scaphoidectomy

Correct Answer & Explanation

. Blatt capsulodesis (dorsal capsulodesis)

Explanation

The Blatt capsulodesis, also known as dorsal capsulodesis, is a surgical technique used to stabilize the scapholunate joint, often in chronic scapholunate dissociation following perilunate injuries. It involves creating a flap from the dorsal radiocarpal ligament and attaching it to the dorsal aspect of the scaphoid and lunate to restrict excessive scaphoid flexion. The Brunelli procedure uses a flexor carpi radialis (FCR) slip. Rappaport and Ramon's tenodesis are not standard terms for this approach. Watson scaphoidectomy is part of a SLAC wrist salvage.

Question 449

Topic: Wrist & Carpus

What is the critical differentiating factor between a dorsal perilunate dislocation and a dorsal trans-scaphoid perilunate dislocation?

. The direction of lunate displacement
. The involvement of median nerve compression
. The presence of an associated scaphoid fracture
. The degree of soft tissue swelling
. The patient's age and activity level

Correct Answer & Explanation

. The presence of an associated scaphoid fracture

Explanation

The critical differentiating factor is the presence of an associated scaphoid fracture. In a dorsal perilunate dislocation, the entire carpus (excluding the lunate) displaces dorsally, and the scapholunate ligament typically ruptures. In a dorsal trans-scaphoid perilunate dislocation, the scaphoid fractures instead of the scapholunate ligament tearing, and the fracture fragments displace along with the rest of the carpus. This has significant implications for surgical management.

Question 450

Topic: Wrist & Carpus

In the context of lunate dislocation, what is the significance of the capitolunate angle?

. It measures the rotation of the lunate on the AP view
. It assesses the integrity of the lunotriquetral ligament
. It is used to quantify the degree of ulnar variance
. It indicates the relationship between the lunate and the capitate on a lateral view, reflecting sagittal plane alignment
. It measures the scapholunate interval

Correct Answer & Explanation

. It indicates the relationship between the lunate and the capitate on a lateral view, reflecting sagittal plane alignment

Explanation

The capitolunate angle is measured on a true lateral radiograph and indicates the relationship between the longitudinal axes of the capitate and the lunate. Normally, this angle should be less than 30 degrees. An increased capitolunate angle (>30 degrees) suggests disruption of the normal sagittal alignment of the midcarpal joint, commonly seen in DISI (lunate dorsiflexed) or VISI (lunate volaflexed). It directly reflects sagittal plane alignment, unlike the other options.

Question 451

Topic: Wrist & Carpus
Regarding the Mayfield classification, what event signifies the transition from Stage III to Stage IV, resulting in a true lunate dislocation?
. Rupture of the scapholunate ligament
. Disruption of the capitolunate articulation
. Tear of the triquetrolunate ligament
. Disruption of the radiolunate articulation and volar displacement of the lunate
. Fracture of the radial styloid

Correct Answer & Explanation

. Disruption of the radiolunate articulation and volar displacement of the lunate

Explanation

Mayfield Stage IV, a true lunate dislocation, occurs when the entire perilunate arc of instability is completed. This means the lunate loses its final articulation, the radiolunate articulation, allowing it to displace volarly. Stage I is scapholunate, Stage II is capitolunate, Stage III is triquetrolunate. The final stage is the disruption of the radiolunate ligament, leading to the lunate's volar displacement.

Question 452

Topic: Wrist & Carpus

A patient is undergoing open reduction and internal fixation of a perilunate dislocation. During the procedure, the dorsal aspect of the scapholunate interosseous ligament is found to be avulsed from the lunate. What specific suture technique is commonly used to repair this type of ligamentous injury?

. Simple interrupted sutures to the capsule
. Horizontal mattress sutures to reinforce the volar capsule
. Transosseous sutures through drill holes in the lunate to reattach the ligament
. Loop sutures around the scaphoid to secure it to the radius
. Non-absorbable sutures to bridge the defect without bone anchorage

Correct Answer & Explanation

. Transosseous sutures through drill holes in the lunate to reattach the ligament

Explanation

When a ligament, such as the scapholunate interosseous ligament, is avulsed from its bony insertion (e.g., from the lunate), transosseous sutures are typically used. This involves drilling small holes through the bone (lunate in this case) and passing the sutures through the avulsed ligament, then through the bone, to re-anchor the ligament securely to its anatomical insertion. Simple interrupted sutures to the capsule or bridging sutures are generally insufficient for reattaching a ligament avulsed from bone. Horizontal mattress is a general technique, but transosseous specifically addresses avulsion from bone.

Question 453

Topic: Wrist & Carpus

Which of the following describes the anatomical position of the lunate relative to the capitate in a dorsal perilunate dislocation?

. The lunate is displaced volarly relative to the capitate
. The lunate is displaced dorsally relative to the capitate
. The capitate is displaced volarly relative to the lunate
. The capitate is displaced dorsally relative to the lunate
. The lunate and capitate maintain normal articulation

Correct Answer & Explanation

. The capitate is displaced dorsally relative to the lunate

Explanation

In a dorsal perilunate dislocation, the lunate maintains its articulation with the distal radius, but the capitate (and the rest of the carpus) dislocates dorsally relative to the lunate. Therefore, the capitate is displaced dorsally relative to the lunate. If the lunate itself displaces volarly, it is a true lunate dislocation. Understanding this relationship is fundamental to differentiating these injuries.

Question 454

Topic: Wrist & Carpus

A 10-year-old child presents with a Galeazzi-type injury. Compared to adults, what is the most common management approach?

. Always requires ORIF of the radius and DRUJ stabilization
. External fixation is the preferred method
. Closed reduction and long arm cast immobilization are often successful
. Ulnar shortening osteotomy is typically performed
. Observation with close follow-up

Correct Answer & Explanation

. Closed reduction and long arm cast immobilization are often successful

Explanation

In children, due to greater remodeling potential and thicker periosteum, closed reduction of the radial fracture and subsequent cast immobilization (usually a long arm cast with the forearm in supination or neutral to stabilize the DRUJ) are often successful, provided anatomical reduction of the radial shaft and stability of the DRUJ can be achieved. ORIF is reserved for unstable or irreducible cases. This is a key difference from adult management.

Question 455

Topic: Wrist & Carpus

Post-operatively for a Galeazzi fracture treated with ORIF, what is the primary goal of early rehabilitation regarding the DRUJ?

. Immediate full range of motion exercises for the DRUJ
. Maintaining forearm immobilization in full pronation
. Protecting the DRUJ while initiating forearm rotation only after pin removal (if used)
. Strengthening the wrist flexors to stabilize the DRUJ
. Applying continuous passive motion to the wrist and forearm

Correct Answer & Explanation

. Protecting the DRUJ while initiating forearm rotation only after pin removal (if used)

Explanation

The primary goal of early rehabilitation after Galeazzi ORIF, especially if the DRUJ was unstable and temporarily pinned, is to protect the DRUJ. This means maintaining forearm immobilization (typically in supination if pins were used for dorsal instability) until the pins are removed (usually 4-6 weeks) to allow capsuloligamentous healing. Initiating gentle, controlled forearm rotation begins only after pin removal and clinical assessment of DRUJ stability. Early aggressive motion could disrupt healing and lead to recurrent instability.

Question 456

Topic: Wrist & Carpus

A patient with a Galeazzi malunion presents with chronic pain and limited forearm rotation. The radial shaft is shortened by 10mm. Which salvage procedure might be considered for the DRUJ pathology?

. Scaphoidectomy
. Trapezectomy
. Darrach procedure (ulnar head excision)
. Staple arthrodesis of the DRUJ
. Radial styloidectomy

Correct Answer & Explanation

. Darrach procedure (ulnar head excision)

Explanation

In cases of symptomatic Galeazzi malunion with radial shortening leading to painful positive ulnar variance and DRUJ pathology, a Darrach procedure (excision of the distal ulna or ulnar head) can be considered as a salvage procedure. This procedure aims to relieve impingement and restore forearm rotation by effectively creating a pseudoarthrosis at the DRUJ. Other options like Sauve-Kapandji (arthrodesis of DRUJ with pseudoarthrosis proximal to allow rotation) or ulnar shortening osteotomy (to correct ulnar variance) might also be considered depending on the specific deformity and patient factors.

Question 457

Topic: Wrist & Carpus

Which ligament is considered the primary stabilizer of the distal radioulnar joint?

. Radial collateral ligament
. Ulnar collateral ligament
. Dorsal radioulnar ligament of the TFCC
. Palmar radioulnar ligament of the TFCC
. Scapholunate ligament

Correct Answer & Explanation

. Palmar radioulnar ligament of the TFCC

Explanation

The triangular fibrocartilage complex (TFCC) is the primary stabilizer of the DRUJ. Within the TFCC, both the dorsal and palmar (volar) radioulnar ligaments are critical. The palmar radioulnar ligament is the primary stabilizer in supination, and the dorsal radioulnar ligament is the primary stabilizer in pronation. However, generally, the anterior (volar) and posterior (dorsal) limbs are considered the main components providing stability. In the context of the choices, the Palmar radioulnar ligament of the TFCC is generally considered the stronger and most important stabilizer, especially against dorsal subluxation, as the DRUJ commonly dislocates dorsally in Galeazzi fractures with forearm pronation.

Question 458

Topic: Wrist & Carpus

Which of the following is considered a relative contraindication to K-wire stabilization of the DRUJ following Galeazzi fracture ORIF?

. Open fracture
. Significantly comminuted radial shaft fracture
. Concomitant ipsilateral elbow injury
. Unstable DRUJ despite anatomical reduction of the radial shaft
. Presence of an active infection at the surgical site

Correct Answer & Explanation

. Presence of an active infection at the surgical site

Explanation

The presence of an active infection at the surgical site is a significant contraindication to any implant placement, including K-wires, due to the high risk of osteomyelitis and poor healing. While an unstable DRUJ despite radial fixation is anindicationfor K-wire fixation, the other options are either not contraindications or would require addressing separately but don't preclude DRUJ pinning if indicated.

Question 459

Topic: Wrist & Carpus

Which of the following describes the key principle for reduction of the DRUJ in a Galeazzi fracture?

. Direct manipulation and pinning of the ulnar head regardless of radial reduction
. Reduction of the radial shaft with restoration of length, alignment, and rotation often leads to indirect reduction of the DRUJ
. Exclusive reliance on traction with an external fixator
. Open reduction of the DRUJ is always required before radial fixation
. Passive stretching of the interosseous membrane

Correct Answer & Explanation

. Reduction of the radial shaft with restoration of length, alignment, and rotation often leads to indirect reduction of the DRUJ

Explanation

The key principle for DRUJ reduction in a Galeazzi fracture is that restoration of anatomical length, alignment, and rotation of the radial shaft will often indirectly reduce the distal radioulnar joint. The integrity and tension of the interosseous membrane and the DRUJ ligaments are re-established when the radius is anatomically reconstructed. Only if the DRUJ remains unstable after stable radial fixation is direct intervention (e.g., K-wire stabilization, soft tissue repair) typically considered.

Question 460

Topic: Wrist & Carpus

What is the consequence of inadequate restoration of radial length during Galeazzi fracture fixation on the DRUJ?

. Increased stability of the DRUJ due to tighter ligaments
. Negative ulnar variance, leading to potential ulnar impaction syndrome
. Positive ulnar variance, leading to impingement and DRUJ instability
. Increased wrist flexion and extension
. Reduced risk of nerve injury

Correct Answer & Explanation

. Positive ulnar variance, leading to impingement and DRUJ instability

Explanation

Inadequate restoration of radial length (i.e., residual radial shortening) during Galeazzi fracture fixation leads to a positive ulnar variance. This means the ulna becomes relatively long compared to the radius. This altered length relationship causes impingement at the DRUJ, leading to pain, limited forearm rotation, and often persistent or recurrent DRUJ instability due to abnormal tension and kinematics.

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