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7. Hand and Wrist MCQs

Practice Set 189 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 3761

Topic: 7. Hand and Wrist

Which diagnostic finding on plain radiographs would necessitate an immediate surgical consultation in a patient with a wrist injury?

. A non-displaced distal radius fracture
. A minimally displaced intra-articular scaphoid fracture
. A lunate dislocation with associated median nerve paresthesias
. A non-displaced ulnar styloid fracture
. A small avulsion fracture of the triquetrum

Correct Answer & Explanation

. A lunate dislocation with associated median nerve paresthesias

Explanation

A lunate dislocation, especially when associated with median nerve paresthesias, constitutes a surgical emergency. The nerve compression requires urgent reduction (closed or open) to prevent irreversible damage. While other fractures mentioned may require surgical consideration, they typically do not demand the same immediate emergent surgical intervention as an acute lunate dislocation with nerve compromise.

Question 3762

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 3763

Topic: 7. Hand and Wrist
A patient sustained an acute dorsal perilunate dislocation with an associated scaphoid waist fracture (trans-scaphoid perilunate dislocation). After open reduction and internal fixation, what is a specific challenge related to the scaphoid fracture component?
. High risk of ulnar nerve compression
. Difficulties in achieving stable fixation due to poor bone quality
. High incidence of scaphoid nonunion or avascular necrosis
. Inability to repair associated ligamentous injuries
. Increased risk of Kienböck's disease in the contralateral wrist

Correct Answer & Explanation

. High incidence of scaphoid nonunion or avascular necrosis

Explanation

Trans-scaphoid perilunate dislocations carry a high incidence of scaphoid nonunion or avascular necrosis (AVN) of the proximal pole of the scaphoid. The scaphoid's blood supply enters predominantly distally and dorsally. A waist fracture can disrupt this supply, especially to the proximal pole. This complicates healing and necessitates meticulous fixation and often bone grafting. Ulnar nerve compression is less common than median nerve compression. Bone quality is not necessarily poor. Associated ligamentous injuries can and should be repaired. Kienböck's in the contralateral wrist is unrelated.

Question 3764

Topic: 7. Hand and Wrist

Which specific K-wire configuration is commonly used to stabilize the scapholunate articulation after reduction of a perilunate dislocation?

. Pinning from the radius to the lunate
. Pinning from the ulna to the triquetrum
. Pinning from the scaphoid to the lunate, and from the capitate to the lunate
. Pinning from the metacarpals to the carpal bones
. Pinning from the triquetrum to the hamate

Correct Answer & Explanation

. Pinning from the scaphoid to the lunate, and from the capitate to the lunate

Explanation

To stabilize the scapholunate articulation and maintain the reduction of the lunate within the carpal rows, K-wires are typically placed from the scaphoid into the lunate, and from the capitate into the lunate. This 'sandwich' fixation helps to maintain the critical relationship of the lunate with both the scaphoid and the capitate, preventing both scapholunate dissociation and capitolunate instability. Pinning from the radius to the lunate is also often done to stabilize the radiolunate articulation, but the question specifically asks about scapholunate. Other options are for different joints or stability patterns.

Question 3765

Topic: 7. Hand and Wrist

What is the most common direction of displacement for the lunate in a true lunate dislocation?

. Dorsal
. Ulnar
. Volar
. Radial
. Proximal

Correct Answer & Explanation

. Volar

Explanation

In a true lunate dislocation, the lunate almost universally dislocates volarly into the carpal tunnel, losing its articulation with both the distal radius and the capitate. This is in contrast to a perilunate dislocation where the lunate remains in place, and the rest of the carpus displaces dorsally around it.

Question 3766

Topic: 7. Hand and Wrist

Which clinical sign, if present, would indicate a high probability of successful closed reduction of a lunate dislocation, even before confirmation with radiographs?

. Increased pain after manipulation
. Audible 'clunk' and immediate relief of median nerve symptoms
. Persistent wrist deformity
. Inability to move the fingers
. Development of new paresthesias

Correct Answer & Explanation

. Audible 'clunk' and immediate relief of median nerve symptoms

Explanation

An audible 'clunk' or 'thud' during the reduction maneuver, coupled with immediate and significant relief of median nerve symptoms (if present), is a strong clinical indicator of successful closed reduction of a lunate dislocation. This suggests the lunate has popped back into its anatomical position, decompressing the nerve. The other options suggest either an unsuccessful reduction or complications.

Question 3767

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 3768

Topic: 7. Hand and Wrist

After open reduction and internal fixation of a perilunate dislocation, what is the most important component of the initial rehabilitation phase (post-immobilization)?

. Aggressive passive stretching into hyperextension
. High-resistance strengthening exercises
. Gentle, active and active-assisted range of motion exercises in protected arcs
. Immediate return to sports activities
. Complete avoidance of all wrist motion for another 6 weeks

Correct Answer & Explanation

. Gentle, active and active-assisted range of motion exercises in protected arcs

Explanation

Following the immobilization period (typically 6-8 weeks) after ORIF of a perilunate dislocation, the initial rehabilitation phase should focus on gentle, active and active-assisted range of motion exercises within protected arcs. The goal is to gradually restore motion without stressing the healing ligaments or risking redislocation. Aggressive stretching, high-resistance exercises, or immediate return to sports would jeopardize the repair. Complete avoidance of motion would lead to severe stiffness.

Question 3769

Topic: 7. Hand and Wrist
A patient presents with persistent wrist pain and difficulty with grip strength 1 year after a lunate dislocation was managed with closed reduction and casting. Radiographs now show sclerosis and collapse of the lunate with associated radial shortening. What is the most likely diagnosis?
. Scaphoid nonunion
. Pisotriquetral arthritis
. Kienböck's disease (post-traumatic avascular necrosis of the lunate)
. Distal radioulnar joint instability
. Carpal tunnel syndrome

Correct Answer & Explanation

. Kienböck's disease (post-traumatic avascular necrosis of the lunate)

Explanation

Sclerosis and collapse of the lunate with associated radial shortening (due to the collapsed lunate) after a lunate dislocation is characteristic of Kienböck's disease, specifically post-traumatic avascular necrosis of the lunate. Lunate dislocation can disrupt the lunate's precarious blood supply, leading to AVN. While other complications are possible, this specific constellation of findings points to Kienböck's disease. Carpal tunnel syndrome could be present but doesn't explain the bone changes.

Question 3770

Topic: 7. Hand and Wrist

Which of the following describes the 'Signet Ring Sign' on an AP wrist radiograph in the context of carpal instability?

. The lunate appearing triangular or 'piece of pie' shaped
. An overlap of the scaphoid and lunate
. A foreshortened scaphoid, appearing round and sclerotic due to flexion
. A widened space between the capitate and hamate
. The ulna appearing shorter than the radius

Correct Answer & Explanation

. A foreshortened scaphoid, appearing round and sclerotic due to flexion

Explanation

The 'Signet Ring Sign' on an AP wrist radiograph refers to a foreshortened, rounded, and often sclerotic appearance of the scaphoid. This occurs when the scaphoid is abnormally flexed (due to scapholunate ligament disruption), causing its distal pole to overlap the proximal pole, giving it the appearance of a signet ring. This is a classic sign of scapholunate dissociation and dorsal intercalated segmental instability (DISI).

Question 3771

Topic: 7. Hand and Wrist

What is the approximate incidence of median nerve compression in acute lunate dislocations?

. Less than 10%
. 10-25%
. 25-50%
. Over 50%
. Rarely observed

Correct Answer & Explanation

. Over 50%

Explanation

Median nerve compression symptoms occur in a significant number of acute lunate dislocations, with reported incidences ranging from 25% to over 50%. The volarly displaced lunate directly impinges on the nerve within the unyielding carpal tunnel, making it a common and urgent concern requiring prompt reduction.

Question 3772

Topic: 7. Hand and Wrist

When planning an open reduction of a lunate dislocation, what is the preferred incision for optimal exposure of the volar aspect of the wrist and the median nerve?

. Longitudinal incision along the ulnar border of the wrist
. Dorsal longitudinal incision centered over the Lister's tubercle
. Longitudinal incision slightly radial to the thenar crease in the palm extending proximally
. Zig-zag or carpal tunnel type incision across the wrist crease, extending proximally
. Transverse incision at the level of the distal radioulnar joint

Correct Answer & Explanation

. Longitudinal incision slightly radial to the thenar crease in the palm extending proximally

Explanation

For volar exposure to decompress the median nerve and repair volar ligaments in a lunate dislocation, a longitudinal incision, typically a modified carpal tunnel incision, is often preferred. It usually starts in the palm, slightly radial to the thenar crease (to avoid injuring the recurrent motor branch of the median nerve), and extends proximally across the wrist crease towards the distal forearm. This provides good visualization while minimizing potential for neurovascular injury. A zig-zag incision across the wrist crease is often used for carpal tunnel release but needs careful extension for dislocation. Dorsal incision is for dorsal structures. Ulnar or transverse incisions are not suitable for primary volar exposure.

Question 3773

Topic: 7. Hand and Wrist

In the context of carpal kinematics, which of the following best describes the normal movement of the lunate during radial deviation of the wrist?

. It extends and translates radially
. It flexes and translates ulnarly
. It extends and translates ulnarly
. It flexes and translates radially
. It remains static without significant translation

Correct Answer & Explanation

. It extends and translates ulnarly

Explanation

During normal radial deviation of the wrist, the lunate extends (dorsiflexes) and translates ulnarly. Conversely, during ulnar deviation, the lunate flexes (volarflexes) and translates radially. This complex kinematic pattern is essential for normal wrist motion and is disrupted in carpal instability. This understanding is crucial for appreciating the mechanics behind perilunate and lunate dislocations.

Question 3774

Topic: 7. Hand and Wrist

Which factor, when present in a patient with a lunate dislocation, may make closed reduction more challenging due to soft tissue interposition?

. Associated ulnar styloid fracture
. Patient with generalized ligamentous laxity
. Chronic dislocation (>3 weeks)
. High-energy injury mechanism
. Absence of median nerve symptoms

Correct Answer & Explanation

. Chronic dislocation (>3 weeks)

Explanation

Chronic dislocations (generally >3 weeks) become significantly more challenging to reduce closed due to the development of adhesions, fibrosis, muscle spasm, and swelling around the dislocated carpal bones, leading to soft tissue interposition that physically blocks reduction. While high-energy injury can cause more complex trauma, the chronicity itself is the primary factor for soft tissue interposition. Ligamentous laxity might theoretically make reduction easier, but also less stable post-reduction. Ulnar styloid fracture is bony, not soft tissue interposition. Absence of nerve symptoms doesn't affect mechanical reduction difficulty.

Question 3775

Topic: 7. Hand and Wrist

What type of carpal instability results from the failure of the lunotriquetral ligament?

. DISI
. SLAC
. SNAC
. VISI
. Scapholunate dissociation

Correct Answer & Explanation

. VISI

Explanation

Failure of the lunotriquetral ligament (LTIL) leads to Volar Intercalated Segmental Instability (VISI). In VISI, the lunate takes on a volaflexed posture (volar tilt) due to the loss of its dorsal connection to the triquetrum. This often results in an increased capitolunate angle, with the capitate extending dorsally relative to the lunate. DISI results from scapholunate ligament failure, leading to dorsal tilt of the lunate.

Question 3776

Topic: 7. Hand and Wrist

When considering the long-term prognosis of a successfully treated lunate or perilunate dislocation, what is the most significant determinant of functional outcome?

. Patient's age at the time of injury
. Pre-existing wrist arthritis
. The success of anatomical reduction and stable fixation of all components
. The duration of post-operative cast immobilization
. The use of prophylactic antibiotics

Correct Answer & Explanation

. The success of anatomical reduction and stable fixation of all components

Explanation

The most significant determinant of long-term functional outcome in lunate or perilunate dislocations is the success of anatomical reduction and stable fixation of all components (bones and ligaments). Meticulous restoration of carpal alignment and stability is crucial to prevent chronic instability, progressive arthritis (SLAC wrist), and functional deficits. While other factors play a role, anatomical reduction is paramount. Pre-existing arthritis is a contraindication to reconstructive surgery and points to salvage. Duration of cast and prophylactic antibiotics are important but secondary to achieving stable anatomical reduction.

Question 3777

Topic: 7. Hand and Wrist

Which view on a wrist radiograph is best for evaluating Gilula's lines?

. Lateral view
. Oblique view
. AP view
. Radial deviation view
. Clenched-fist AP view

Correct Answer & Explanation

. AP view

Explanation

Gilula's lines, which are used to assess the smooth curvilinear alignment of the proximal and distal carpal rows, are best evaluated on a standard AP (Anteroposterior) view of the wrist. Disruption of these lines indicates carpal instability or dislocation.

Question 3778

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 3779

Topic: 7. Hand and Wrist

Following reduction of a perilunate dislocation, what specific finding on CT scan would confirm adequate reduction and good prognosis, assuming no associated fractures?

. A 3mm scapholunate interval
. A capitolunate angle of 45 degrees
. Smooth articulation between the lunate and radius, and lunate and capitate
. A residual volar tilt of the lunate
. Slight widening of the midcarpal joint

Correct Answer & Explanation

. Smooth articulation between the lunate and radius, and lunate and capitate

Explanation

Adequate reduction of a perilunate dislocation means that the carpal bones are restored to their anatomical relationships. A CT scan confirming smooth articulation between the lunate and radius (radiocarpal joint), and the lunate and capitate (midcarpal joint), indicates proper alignment and a good reduction. A 3mm scapholunate interval is borderline to abnormal (typically <2mm or <3mm for dynamic instability). A capitolunate angle of 45 degrees indicates persistent DISI or VISI and is not adequate. Residual volar tilt of the lunate indicates VISI and inadequate reduction. Slight widening of the midcarpal joint indicates persistent instability.

Question 3780

Topic: 7. Hand and Wrist
What is the primary role of wrist arthrodesis in the management of lunate dislocation?
. To prevent median nerve compression in acute cases
. To preserve full wrist range of motion in chronic cases
. As a salvage procedure for severe, chronic, painful, and unmanageable carpal instability/arthritis
. To primarily treat Kienböck's disease without dislocation
. To facilitate a quicker return to high-impact sports

Correct Answer & Explanation

. As a salvage procedure for severe, chronic, painful, and unmanageable carpal instability/arthritis

Explanation

Wrist arthrodesis (fusion) is a salvage procedure typically reserved for severe, chronic, painful, and unmanageable carpal instability or arthritis resulting from long-standing lunate/perilunate dislocations, failed reconstructive surgeries, or advanced SLAC/SNAC wrist. It aims to eliminate pain by fusing the wrist bones, sacrificing all motion. It does not preserve motion, is not for acute nerve compression (though it can indirectly alleviate chronic nerve symptoms), nor is it a primary treatment for Kienböck's without dislocation, and it certainly does not facilitate a quicker return to high-impact sports due to complete loss of motion.

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