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7. Hand and Wrist MCQs

Practice Set 192 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 3821

Topic: 7. Hand and Wrist

In a patient undergoing ORIF for a Galeazzi fracture, a dorsal approach (Thompson approach) to the radius might be chosen. Which neurovascular structure is most at risk with this approach?

. Median nerve
. Ulnar nerve
. Radial artery
. Superficial radial nerve
. Posterior interosseous nerve (PIN)

Correct Answer & Explanation

. Posterior interosseous nerve (PIN)

Explanation

The Posterior Interosseous Nerve (PIN), a motor branch of the radial nerve, is most vulnerable during a dorsal approach (Thompson approach) to the radial shaft. It passes through the supinator muscle, and excessive retraction, direct injury, or entrapment during dissection can lead to a wrist drop and inability to extend the fingers at the MCP joints. The superficial radial nerve is also a concern, as it is sensory and can be injured with skin incisions or superficial dissection.

Question 3822

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 3823

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 3824

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.

Question 3825

Topic: 7. Hand and Wrist

When assessing the DRUJ intraoperatively after radial fixation, how is stability typically tested?

. By applying an axial load through the wrist
. By assessing passive range of motion of the wrist in flexion and extension
. By gently pronating and supinating the forearm while stabilizing the radius and observing for ulnar head subluxation
. By performing a scaphoid shift test
. By evaluating the integrity of the interosseous membrane visually

Correct Answer & Explanation

. By gently pronating and supinating the forearm while stabilizing the radius and observing for ulnar head subluxation

Explanation

After stable fixation of the radial shaft, DRUJ stability is typically tested by gently pronating and supinating the forearm. The surgeon stabilizes the radius and observes or palpates for any excessive translation or subluxation of the ulnar head relative to the sigmoid notch of the radius. Comparison to the contralateral side, if uninjured, is helpful. Persistent instability warrants further intervention (e.g., K-wire fixation).

Question 3826

Topic: Wrist & Carpus

What is the recommended period of K-wire stabilization for an unstable DRUJ after Galeazzi fracture fixation?

. 1-2 weeks
. 2-3 weeks
. 4-6 weeks
. 8-10 weeks
. 12 weeks or more

Correct Answer & Explanation

. 4-6 weeks

Explanation

If K-wire stabilization of the DRUJ is performed, it is typically maintained for 4-6 weeks. This duration allows for sufficient capsuloligamentous healing of the DRUJ stabilizers (primarily the TFCC) while minimizing the risk of pin-site infection, pin loosening, and joint stiffness. After removal, a gradual progression of forearm range of motion exercises is initiated.

Question 3827

Topic: Wrist & Carpus

Which of the following anatomical structures is crucial for maintaining stability of the DRUJ against proximal migration of the radius?

. The pronator teres muscle
. The supinator muscle
. The interosseous membrane
. The extensor carpi radialis longus tendon
. The flexor digitorum profundus

Correct Answer & Explanation

. The interosseous membrane

Explanation

The interosseous membrane (IOM) is a critical stabilizer of the forearm, particularly against proximal migration of the radius. Its fibers are obliquely oriented from the radius distally and medially to the ulna proximally. This allows it to transmit axial loads from the radius to the ulna and resist forces that would otherwise cause the radius to shorten relative to the ulna, thereby protecting the DRUJ.

Question 3828

Topic: 7. Hand and Wrist

During the surgical approach to a distal radial shaft fracture, what anatomical landmark is often used to identify and protect the anterior interosseous nerve (AIN)?

. Superficial to the pronator teres
. Deep to the brachioradialis
. On the interosseous membrane, deep to the flexor digitorum profundus and lateral to the flexor pollicis longus
. Proximal to the arcade of Frohse
. Within the carpal tunnel

Correct Answer & Explanation

. On the interosseous membrane, deep to the flexor digitorum profundus and lateral to the flexor pollicis longus

Explanation

During a volar (Henry) approach to the distal radial shaft, after retracting the brachioradialis and potentially detaching the pronator quadratus, the anterior interosseous nerve (AIN) is found on the interosseous membrane, running between the flexor pollicis longus (radially) and the flexor digitorum profundus (medially and ulnarly). It is crucial to identify and protect this nerve during dissection and plate application.

Question 3829

Topic: Wrist & Carpus

Which of the following statements regarding the stability of the DRUJ in a Galeazzi fracture is TRUE?

. The DRUJ is always stable once the radial fracture is reduced.
. DRUJ instability is more common with a fracture located in the proximal third of the radius.
. The DRUJ typically dislocates volarly with forearm pronation.
. DRUJ instability is inversely proportional to the degree of radial shortening.
. The DRUJ is inherently unstable due to the loss of radial support and potential ligamentous injury.

Correct Answer & Explanation

. The DRUJ is inherently unstable due to the loss of radial support and potential ligamentous injury.

Explanation

The DRUJ in a Galeazzi fracture is inherently unstable primarily due to the loss of stable bony support from the fractured radial shaft and often concomitant injury to the triangular fibrocartilage complex (TFCC) and its stabilizing ligaments. Restoring radial length and alignment is crucial but does not guarantee DRUJ stability, necessitating intraoperative assessment.

Question 3830

Topic: 7. Hand and Wrist

After ORIF of a Galeazzi fracture, a patient reports pain with palpation directly over the fovea of the ulna. This, combined with clicking during forearm rotation, is most suggestive of:

. Nonunion of the radial shaft
. Extensor Carpi Ulnaris (ECU) subluxation
. Triangular Fibrocartilage Complex (TFCC) injury
. Carpal Tunnel Syndrome
. Osteoarthritis of the midcarpal joint

Correct Answer & Explanation

. Triangular Fibrocartilage Complex (TFCC) injury

Explanation

Tenderness over the fovea of the ulna, often referred to as the 'fovea sign', is a strong indicator of injury to the triangular fibrocartilage complex (TFCC), particularly its foveal attachment. Combined with clicking during forearm rotation, this suggests a traumatic TFCC tear, which is a common finding or persistent issue in Galeazzi injuries and can contribute to DRUJ instability. Other options are less directly linked to this specific clinical presentation.

Question 3831

Topic: 7. Hand and Wrist

When performing K-wire stabilization of the DRUJ, what is the ideal direction and location for pin placement?

. From the dorsal ulna into the radius, avoiding the extensor tendons
. From the volar radius into the ulna, avoiding the median nerve
. From the distal ulna styloid into the carpals
. From the proximal radius into the ulna, through the interosseous membrane
. From the ulnar side of the wrist into the radial styloid

Correct Answer & Explanation

. From the dorsal ulna into the radius, avoiding the extensor tendons

Explanation

For K-wire stabilization of the DRUJ, pins are typically inserted from the dorsal aspect of the ulna, across the reduced DRUJ, and into the radius. This technique helps maintain reduction and avoids vital neurovascular structures if performed carefully. It is critical to ensure the pins do not impinge on the extensor tendons or pass through their sheaths, which can lead to tenosynovitis or rupture.

Question 3832

Topic: 7. Hand and Wrist

Which of the following is NOT a component of the Triangular Fibrocartilage Complex (TFCC)?

. Articular disc
. Meniscus homolog
. Dorsal radioulnar ligament
. Palmar radioulnar ligament
. Scapholunate ligament

Correct Answer & Explanation

. Scapholunate ligament

Explanation

The TFCC is a complex structure at the ulnar aspect of the wrist comprising the articular disc, meniscus homolog, dorsal and palmar radioulnar ligaments, and the ulnocarpal ligaments (ulnolunate and ulnotriquetral). The scapholunate ligament is a major intrinsic carpal ligament, crucial for carpal stability, but it is not considered a component of the TFCC.

Question 3833

Topic: Wrist & Carpus

A patient is undergoing revision surgery for a chronic, painful Galeazzi malunion with severe positive ulnar variance and irreducible DRUJ arthritis. Which salvage procedure would be most appropriate in this scenario?

. Limited intercarpal fusion
. Proximal row carpectomy
. Sauve-Kapandji procedure
. Wrist arthrodesis
. Radial shortening osteotomy

Correct Answer & Explanation

. Sauve-Kapandji procedure

Explanation

For chronic, painful Galeazzi malunion with severe positive ulnar variance and irreducible DRUJ arthritis, the Sauve-Kapandji procedure (distal ulna pseudoarthrosis with DRUJ fusion) or a Darrach procedure (ulnar head excision) are considered salvage options. The Sauve-Kapandji preserves the distal ulna for stability while allowing forearm rotation through a created pseudoarthrosis proximal to the fused DRUJ. Radial shortening osteotomy would address the positive ulnar variance but not the irreducible arthritis. Wrist arthrodesis is a more extensive procedure for diffuse wrist arthritis.

Question 3834

Topic: Wrist & Carpus

Which of the following is a critical intraoperative assessment to ensure successful fixation of a Galeazzi fracture?

. Assessment of median nerve conductivity using nerve stimulator.
. Fluoroscopic imaging to confirm complete union of the fracture fragments.
. Testing forearm rotation with the DRUJ unpinned to confirm stability after radial fixation.
. Measuring the length of the radius with a ruler to ensure it is 24cm.
. Verifying no damage to the extensor carpi ulnaris tendon.

Correct Answer & Explanation

. Testing forearm rotation with the DRUJ unpinned to confirm stability after radial fixation.

Explanation

A critical intraoperative step after achieving stable internal fixation of the radial shaft in a Galeazzi fracture is to dynamically assess the stability of the DRUJ by gently pronating and supinating the forearm. If the DRUJ remains unstable without K-wire stabilization, then further intervention, such as temporary K-wire fixation or TFCC repair, is required to prevent persistent instability and poor functional outcomes.

Question 3835

Topic: Wrist & Carpus

What post-operative instruction is crucial for patients with Galeazzi fracture who have undergone K-wire stabilization of the DRUJ?

. Begin immediate active forearm rotation exercises.
. Maintain strict immobilization of the forearm until K-wires are removed.
. Start passive wrist range of motion exercises on postoperative day 1.
. Apply direct pressure to the K-wire entry sites multiple times daily.
. Remove the cast on day 7 and apply an elastic bandage.

Correct Answer & Explanation

. Maintain strict immobilization of the forearm until K-wires are removed.

Explanation

Maintaining strict immobilization of the forearm (usually in a long arm cast or splint) is crucial when K-wires are in place for DRUJ stabilization. This protects the healing ligaments and prevents dislodgement of the wires, which could lead to loss of reduction or pin-site complications. Active forearm rotation is contraindicated until the pins are removed and DRUJ stability is confirmed.

Question 3836

Topic: Wrist & Carpus

What is the primary role of the pronator quadratus muscle in the context of a Galeazzi fracture?

. It is primarily a supinator of the forearm.
. It provides vascular supply to the distal radius.
. It is a key pronator of the forearm and contributes to DRUJ stability.
. It acts as a wrist extensor.
. It stabilizes the elbow joint.

Correct Answer & Explanation

. It is a key pronator of the forearm and contributes to DRUJ stability.

Explanation

The pronator quadratus is the most distal of the pronator muscles and plays a critical role as a strong pronator of the forearm. It also acts as a primary dynamic stabilizer of the distal radioulnar joint (DRUJ), maintaining apposition of the radius and ulna. Its fibers run transversely, and its integrity is important for DRUJ function. It can be injured or interposed in Galeazzi fractures.

Question 3837

Topic: Wrist & Carpus

What defines a 'bayonet apposition' on radiographs of a forearm fracture?

. Fragments are angulated more than 30 degrees
. Fragments are aligned end-to-end but separated by more than 5mm
. Fragments are overlapping with no end-to-end contact
. Fragments are rotated by more than 45 degrees
. Fragments are minimally displaced and in stable contact

Correct Answer & Explanation

. Fragments are overlapping with no end-to-end contact

Explanation

Bayonet apposition describes a fracture pattern where the fracture fragments are overlapping but without end-to-end contact. This typically results in shortening of the bone, which in a Galeazzi fracture is detrimental as it leads to positive ulnar variance and DRUJ impingement/instability. It is a sign of significant displacement and instability.

Question 3838

Topic: 7. Hand and Wrist

What is the main concern if a Galeazzi fracture malunion leads to chronic positive ulnar variance?

. Increased risk of radial nerve palsy
. Ulnar impaction syndrome and DRUJ arthritis
. Carpal tunnel syndrome
. Flexor tendon adhesions
. Avascular necrosis of the distal ulna

Correct Answer & Explanation

. Ulnar impaction syndrome and DRUJ arthritis

Explanation

Chronic positive ulnar variance, a common sequela of Galeazzi malunion with radial shortening, can lead to ulnar impaction syndrome. This condition involves the distal ulna impinging on the lunate and triquetrum, causing pain, especially with ulnar deviation and pronation. It can also lead to degenerative changes and arthritis of the DRUJ and ulnocarpal joint.

Question 3839

Topic: Wrist & Carpus

Which soft tissue structure provides the primary support against dorsal displacement of the ulna at the DRUJ in supination?

. Dorsal radioulnar ligament of TFCC
. Palmar radioulnar ligament of TFCC
. Extensor Carpi Ulnaris tendon sheath
. Interosseous membrane
. Ulnocarpal ligament

Correct Answer & Explanation

. Palmar radioulnar ligament of TFCC

Explanation

The palmar (volar) radioulnar ligament, a component of the TFCC, is the primary stabilizer against dorsal translation of the ulna relative to the radius, especially when the forearm is in supination. The dorsal radioulnar ligament serves a similar role but primarily against volar translation in pronation. Together, they are crucial for DRUJ stability.

Question 3840

Topic: Wrist & Carpus

Which imaging modality can be particularly useful in evaluating the soft tissue structures of the DRUJ (e.g., TFCC) in the context of persistent instability after Galeazzi fixation?

. Standard radiographs
. Computed Tomography (CT) scan
. Magnetic Resonance Imaging (MRI) scan
. Bone scintigraphy
. Fluoroscopy

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI) scan

Explanation

Magnetic Resonance Imaging (MRI) is the gold standard for evaluating soft tissue structures like the Triangular Fibrocartilage Complex (TFCC), ligaments, and capsule around the DRUJ. In cases of persistent instability after Galeazzi fixation, MRI can provide detailed information about the integrity of the TFCC and other soft tissues that may be contributing to the ongoing instability. CT is excellent for bony anatomy, and fluoroscopy for dynamic assessment, but MRI excels in soft tissue visualization.

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