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7. Hand and Wrist MCQs

Practice Set 253 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 5041

Topic: Nerve & Tendon

A patient sustains a severe laceration to the ulnar nerve at the level of the medial epicondyle. Upon examination, the patient has completely preserved function of the first dorsal interosseous muscle and adductor pollicis, despite profound ulnar sensory loss in the hand. What anatomical variant best explains this clinical picture?

. Riche-Cannieu anastomosis
. Martin-Gruber anastomosis
. Marinacci communication
. Berrettini anastomosis
. Horner's syndrome

Correct Answer & Explanation

. Martin-Gruber anastomosis

Explanation

The Martin-Gruber anastomosis is a communicating neural branch carrying motor fibers from the median nerve (or anterior interosseous nerve) to the ulnar nerve in the proximal forearm. In patients with this variant, a high ulnar nerve lesion (e.g., at the elbow) may spare ulnar-innervated intrinsic hand muscles because their motor supply bypassed the elbow via the median nerve.

Question 5042

Topic: Wrist & Carpus

In Scaphoid Nonunion Advanced Collapse (SNAC), the pattern of degenerative arthritis predictably progresses through specific stages. Unlike Scapholunate Advanced Collapse (SLAC), the radiolunate joint is typically spared in SNAC wrists. What biomechanical mechanism accounts for the preservation of the radiolunate joint in a SNAC wrist?

. The lunate remains tethered to the triquetrum causing volar intercalated segment instability (VISI)
. The distal scaphoid fragment maintains its ligamentous attachment to the lunate
. The intact scapholunate ligament maintains normal lunate extension and concentric radiolunate articulation
. The capitate migrates proximally, unloading the radiolunate joint
. The radioscaphocapitate ligament hypertrophies, shielding the radiolunate facet

Correct Answer & Explanation

. The distal scaphoid fragment maintains its ligamentous attachment to the lunate

Explanation

In a SNAC wrist, the proximal pole of the scaphoid remains firmly attached to the lunate via the intact scapholunate (SL) ligament. This maintains the lunate in a relatively extended but congruous position within the spherical lunate fossa of the radius, thereby preserving the radiolunate joint. The distal scaphoid fragment flexes, leading to progressive arthritis at the radioscaphoid and midcarpal joints.

Question 5043

Topic: 7. Hand and Wrist

A 42-year-old man presents with dactylitis of his index finger, nail pitting, and asymmetric oligoarthritis. Radiographs of his hands reveal marginal erosions with adjacent bone proliferation, described as a 'pencil-in-cup' deformity. He is negative for rheumatoid factor. Which HLA association is most commonly linked to this patient's condition?

. HLA-DR4
. HLA-B27
. HLA-DQ2
. HLA-B8
. HLA-DR2

Correct Answer & Explanation

. HLA-B27

Explanation

The patient has psoriatic arthritis, characterized by dactylitis, nail pitting, and 'pencil-in-cup' deformities. It is a seronegative spondyloarthropathy associated with the HLA-B27 allele. HLA-DR4 is associated with Rheumatoid Arthritis.

Question 5044

Topic: Wrist & Carpus

A randomized controlled trial comparing two surgical techniques for distal radius fractures finds no statistically significant difference in DASH scores at 1 year (p = 0.08). However, a true clinical difference actually exists in the population. This scenario represents which of the following statistical concepts?

. Type I error
. Type II error
. Selection bias
. Confounding
. Observer bias

Correct Answer & Explanation

. Type II error

Explanation

A Type II error (beta error) occurs when a study fails to reject a false null hypothesis—in simpler terms, concluding there is no difference when one truly exists. This is typically due to an inadequate sample size (low statistical power). A Type I error (alpha error) would be finding a difference when none exists (a false positive).

Question 5045

Topic: Wrist & Carpus

During a fluoroscopically assisted closed reduction of a distal radius fracture, the surgeon consciously steps back from the C-arm to reduce scatter radiation exposure. According to the inverse square law of radiation physics, doubling the distance from the primary radiation source reduces the exposure dose to what fraction of the original?

. One-half
. One-third
. One-quarter
. One-eighth
. One-sixteenth

Correct Answer & Explanation

. One-quarter

Explanation

The inverse square law states that the intensity of radiation is inversely proportional to the square of the distance from the source. Therefore, if the distance from the source is doubled (multiplied by 2), the radiation exposure is reduced to 1/(2^2), or one-quarter of the original dose. This is a fundamental principle of radiation safety in the operating room.

Question 5046

Topic: 7. Hand and Wrist

During flexor tendon repair in zone II of the hand, preservation of specific pulleys is paramount. Which of the following flexor tendon pulleys is located over the proximal phalanx and is considered one of the two most critical pulleys to prevent bowstringing?

. A1 pulley
. A2 pulley
. A3 pulley
. A4 pulley
. A5 pulley

Correct Answer & Explanation

. A2 pulley

Explanation

The A2 and A4 pulleys are the most critical for preventing bowstringing and maintaining the biomechanical efficiency of finger flexion. The A2 pulley is situated over the proximal half of the proximal phalanx, while the A4 pulley overlies the middle phalanx.

Question 5047

Topic: 7. Hand and Wrist

A 65-year-old female undergoes open reduction and internal fixation of a distal radius fracture with a volar locked plate. Three months postoperatively, she suddenly loses the ability to actively flex the interphalangeal joint of her thumb. What is the most likely etiology?

. Rupture of the extensor pollicis longus due to dorsal screw penetration
. Iatrogenic traction injury to the anterior interosseous nerve
. Attritional rupture of the flexor pollicis longus due to hardware prominence
. Adhesive capsulitis of the interphalangeal joint
. Avulsion of the FPL insertion at the distal phalanx

Correct Answer & Explanation

. Attritional rupture of the flexor pollicis longus due to hardware prominence

Explanation

Flexor pollicis longus (FPL) tendon rupture is a well-documented complication of volar plating of the distal radius. It typically occurs due to attritional wear over a plate positioned too distally (at or distal to the watershed line) or prominent screw heads on the volar surface.

Question 5048

Topic: Nerve & Tendon

A 45-year-old carpenter presents with progressive numbness in his ring and small fingers, accompanied by grip weakness. Examination reveals a positive Froment's sign and a positive Tinel's sign at the elbow. Compression of the ulnar nerve at the cubital tunnel is diagnosed. Which anatomic structure forms the roof of the cubital tunnel?

. Osborne's ligament
. Struthers' ligament
. Lacertus fibrosus
. Arcade of Frohse
. Transverse carpal ligament

Correct Answer & Explanation

. Osborne's ligament

Explanation

The roof of the cubital tunnel is formed by Osborne's ligament (the cubital tunnel retinaculum) and the overlying fascia of the flexor carpi ulnaris (FCU). The floor is formed by the posterior band of the medial collateral ligament (MCL) and the joint capsule.

Question 5049

Topic: 7. Hand and Wrist

Which of the following represents the most significant primary source of nutrition for the flexor digitorum profundus (FDP) tendon within Zone II of the hand?

. Direct arterial supply from the proper digital arteries via the lumbrical muscles
. Capillary beds branching directly from the periosteum of the phalanges
. Arterial supply via the vincula brevia and vincula longa
. Diffusion from the surrounding synovial fluid within the digital sheath
. Longitudinal intratendinous vessels originating from the musculotendinous junction

Correct Answer & Explanation

. Diffusion from the surrounding synovial fluid within the digital sheath

Explanation

Flexor tendons in Zone II ('no man's land') rely on dual nutrition: vascular perfusion and synovial diffusion. However, diffusion from the surrounding synovial fluid is the primary and most significant source of nutrition for these tendons within the fibro-osseous digital sheath. The vascular supply (via the vincula longa and brevia) only reaches the dorsal surface of the tendons, leaving the volar aspect reliant entirely on diffusion.

Question 5050

Topic: 7. Hand and Wrist

Within the carpal tunnel, the spatial arrangement of the flexor digitorum superficialis (FDS) tendons is highly organized. Which of the following accurately describes their anatomical configuration at the level of the transverse carpal ligament?

. The tendons to the index and middle fingers are volar (superficial) to those of the ring and small fingers.
. The tendons to the middle and ring fingers are volar (superficial) to those of the index and small fingers.
. The tendons to the index and small fingers are volar (superficial) to those of the middle and ring fingers.
. All four FDS tendons lie completely side-by-side in a single coronal plane.
. The tendons to the ring and small fingers are volar (superficial) to those of the index and middle fingers.

Correct Answer & Explanation

. The tendons to the middle and ring fingers are volar (superficial) to those of the index and small fingers.

Explanation

Within the confined space of the carpal tunnel, the flexor digitorum superficialis (FDS) tendons are stacked. The FDS tendons to the middle and ring fingers are situated volar (superficial) to the FDS tendons of the index and small fingers. This specific anatomical arrangement is highly reliable and is clinically relevant during surgical exploration of the carpal tunnel, repair of complex volar wrist lacerations, or when managing isolated tenosynovitis.

Question 5051

Topic: 7. Hand and Wrist
A 30-year-old carpenter sustains a sharp knife laceration to the volar aspect of his index finger at the level of the middle phalanx. On physical examination, he is unable to flex the distal interphalangeal (DIP) joint, but proximal interphalangeal (PIP) joint flexion is fully intact. Based on the Verdan zones of flexor tendon injury, this injury is classified as:
. Zone I injury involving the flexor digitorum superficialis (FDS)
. Zone I injury involving the flexor digitorum profundus (FDP)
. Zone II injury involving both FDS and FDP
. Zone III injury involving the flexor digitorum profundus (FDP)
. Zone V injury involving the common flexor origin

Correct Answer & Explanation

. Zone I injury involving the flexor digitorum profundus (FDP)

Explanation

The inability to flex the DIP joint with preserved PIP flexion localizes the injury to the flexor digitorum profundus (FDP) distal to the insertion of the flexor digitorum superficialis (FDS). The FDS inserts at the middle phalanx. Injuries to the flexor tendon system distal to the FDS insertion are classified as Zone I injuries, and by definition, involve only the FDP tendon.

Question 5052

Topic: 7. Hand and Wrist

A competitive cyclist presents with progressive numbness in the volar aspect of his small finger and the ulnar half of his ring finger. He also notes weakness in spreading his fingers apart. Sensation over the dorsoulnar aspect of the hand is fully intact. This clinical picture is most consistent with compression of the ulnar nerve at which specific anatomic location?

. The cubital tunnel at the elbow
. Zone 1 of Guyon's canal at the wrist
. Zone 2 of Guyon's canal at the wrist
. Zone 3 of Guyon's canal at the wrist
. The Arcade of Struthers

Correct Answer & Explanation

. Zone 1 of Guyon's canal at the wrist

Explanation

The patient has both motor (interossei) and sensory (volar pinky/ring) deficits of the ulnar nerve, but spared dorsal sensation. The dorsal ulnar cutaneous nerve branches off the ulnar nerve approximately 5-8 cm proximal to the wrist. Because dorsal sensation is intact, the lesion must be at the wrist (Guyon's canal) rather than the elbow. In Guyon's canal, Zone 1 is proximal to the bifurcation and contains both mixed motor and sensory fibers. Zone 2 is pure motor, and Zone 3 is pure sensory.

Question 5053

Topic: Hand Trauma & Infection
A 35-year-old mechanic presents with a swollen, painful index finger 3 days after a puncture wound. Examination raises suspicion for pyogenic flexor tenosynovitis. Kanavel's cardinal signs for this condition include all of the following EXCEPT:
. Flexed resting posture of the digit
. Fusiform swelling of the entire digit
. Tenderness along the course of the flexor tendon sheath
. Severe pain elicited by passive flexion of the digit
. Severe pain elicited by passive extension of the digit

Correct Answer & Explanation

. Severe pain elicited by passive flexion of the digit

Explanation

Kanavel's four cardinal signs of flexor tenosynovitis are: 1) flexed resting posture, 2) fusiform (sausage-like) swelling, 3) tenderness along the flexor sheath, and 4) excruciating pain on passive EXTENSION (not flexion), which stretches the inflamed tendon sheath.

Question 5054

Topic: Nerve & Tendon

During a physical examination of the hand, a patient is asked to tightly hold a piece of paper between their thumb and lateral aspect of the index finger (key pinch). The examiner pulls the paper away, and the patient's thumb interphalangeal (IP) joint noticeably flexes. This is a positive Froment's sign. Which muscle is compensating, and what is its innervation?

. Adductor pollicis; Ulnar nerve
. Flexor pollicis brevis; Median nerve
. Flexor pollicis longus; Anterior interosseous nerve
. Abductor pollicis brevis; Median nerve
. First dorsal interosseous; Ulnar nerve

Correct Answer & Explanation

. Adductor pollicis; Ulnar nerve

Explanation

Froment's sign tests for ulnar nerve palsy. The adductor pollicis (innervated by the ulnar nerve) is normally responsible for the key pinch. When it is weak or paralyzed, the patient compensates by using the Flexor Pollicis Longus (FPL) to flex the thumb IP joint to hold the paper. The FPL is innervated by the Anterior Interosseous Nerve (AIN), a branch of the median nerve.

Question 5055

Topic: Nerve & Tendon
A 24-year-old rugby player presents after grabbing an opponent's jersey. He is unable to actively flex the distal interphalangeal (DIP) joint of his ring finger. Radiographs show a small bony avulsion fragment volar to the proximal interphalangeal (PIP) joint. According to the Leddy and Packer classification, what type of injury is this, and what is its vascular implication?
. Type I; the vincula are intact allowing delayed repair
. Type I; the vincula are ruptured requiring repair within 7-10 days
. Type II; the tendon retracts to the PIP joint and is nourished by intact vincula
. Type III; the tendon is retracted to the palm and ischemic
. Type IV; characterized by an intra-articular fracture of the DIP joint

Correct Answer & Explanation

. Type II; the tendon retracts to the PIP joint and is nourished by intact vincula

Explanation

This is a 'Jersey finger' (FDP avulsion). In a Leddy and Packer Type II injury, the tendon retracts to the level of the PIP joint. It is caught by the intact vincula longus, which preserves some blood supply, allowing for a slightly delayed repair compared to a Type I injury (where the tendon retracts to the palm, rupturing vincula, making it ischemic and requiring repair within 7-10 days).

Question 5056

Topic: Wrist & Carpus

A 60-year-old female presents 6 weeks after non-operative management of a minimally displaced distal radius fracture. She reports sudden inability to actively extend her thumb interphalangeal joint. The extensor pollicis longus (EPL) tendon is suspected to have ruptured. What is the most widely accepted mechanism for this complication in non-displaced or minimally displaced fractures?

. Attritional wear from a prominent volar plate
. Primary laceration by sharp bone fragments at the time of injury
. Synovial ischemia due to increased pressure within the intact third dorsal compartment
. Entrapment of the tendon within the fracture site
. Iatrogenic injury from casting

Correct Answer & Explanation

. Synovial ischemia due to increased pressure within the intact third dorsal compartment

Explanation

EPL ruptures are most commonly associated with non-displaced or minimally displaced distal radius fractures. Because the extensor retinaculum remains intact, bleeding and edema increase pressure within the tightly constrained third dorsal compartment, leading to microvascular ischemia and subsequent delayed rupture of the EPL tendon.

Question 5057

Topic: 7. Hand and Wrist

A 24-year-old male sustains a proximal pole scaphoid fracture. Which of the following best describes the primary vascular supply at risk, leading to avascular necrosis?

. Palmar carpal branch of the radial artery
. Superficial palmar arch
. Dorsal carpal branch of the radial artery
. Anterior interosseous artery
. Ulnar artery through the deep palmar arch

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

The scaphoid receives its primary blood supply from the dorsal carpal branch of the radial artery, which enters the bone distally and flows retrograde. Proximal pole fractures are at a high risk for AVN because this retrograde blood supply is disrupted.

Question 5058

Topic: 7. Hand and Wrist

A laceration to the volar aspect of the hand occurs in 'Zone II' of the flexor tendons. What anatomical boundaries define Zone II, historically known as 'no man\'s land'?

. From the distal interphalangeal joint to the insertion of the FDP
. From the proximal aspect of the A1 pulley to the insertion of the FDS
. From the carpal tunnel to the A1 pulley
. From the musculotendinous junction to the carpal tunnel
. From the A1 pulley to the A5 pulley

Correct Answer & Explanation

. From the proximal aspect of the A1 pulley to the insertion of the FDS

Explanation

Zone II is defined as the area from the proximal edge of the A1 pulley (distal palmar crease) to the insertion of the flexor digitorum superficialis (FDS) tendon on the middle phalanx. Both FDS and FDP tendons run tightly together in this fibro-osseous sheath.

Question 5059

Topic: 7. Hand and Wrist

A patient sustains a deep laceration to the palmar aspect of the hand at the level of the proximal phalanx. This injury occurs in flexor tendon 'Zone II'. Which anatomical feature defines this zone?

. Distal to the insertion of the flexor digitorum superficialis (FDS)
. Between the distal palmar crease and the A1 pulley
. From the A1 pulley to the insertion of the flexor digitorum superficialis (FDS)
. Within the carpal tunnel
. Proximal to the carpal tunnel

Correct Answer & Explanation

. From the A1 pulley to the insertion of the flexor digitorum superficialis (FDS)

Explanation

Flexor tendon Zone II, historically known as 'no man\'s land' due to the difficulty of repair and high risk of adhesions, extends from the proximal edge of the A1 pulley to the insertion of the FDS on the middle phalanx. Both the FDS and FDP tendons are enclosed within the same tight fibro-osseous sheath in this zone.

Question 5060

Topic: 7. Hand and Wrist

In the evaluation of suspected Carpal Tunnel Syndrome, which of the following electrodiagnostic findings is typically the earliest and most sensitive indicator of median nerve compression?

. Decreased compound muscle action potential (CMAP) amplitude
. Prolonged distal motor latency
. Decreased sensory nerve action potential (SNAP) amplitude
. Prolonged sensory nerve latency
. Fibrillation potentials in the abductor pollicis brevis

Correct Answer & Explanation

. Prolonged sensory nerve latency

Explanation

In compressive neuropathies such as Carpal Tunnel Syndrome, sensory fibers are typically affected before motor fibers because they are larger and more superficially located within the nerve fascicles. Prolongation of sensory latency across the carpal tunnel is the earliest and most sensitive electrodiagnostic finding. Motor latency prolongation and denervation potentials (fibrillations) represent later, more severe stages of compression.

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