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7. Hand and Wrist MCQs

Practice Set 59 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 1161

Topic: 7. Hand and Wrist
An infant presents with a hypoplastic thumb. Exam reveals an absent thenar eminence, a narrowed first web space, and an unstable carpometacarpal (CMC) joint. Radiographs show partial absence of the first metacarpal. According to the Blauth classification, what is the most appropriate definitive management?
. Reconstruction with web space deepening and Huber transfer
. Distraction osteogenesis of the first metacarpal
. Index finger pollicization
. Nonoperative management with a spica splint
. Microvascular free toe transfer

Correct Answer & Explanation

. Index finger pollicization

Explanation

This is a Blauth Type IIIB thumb hypoplasia, characterized by an unstable CMC joint. The treatment of choice is ablation of the hypoplastic thumb and index finger pollicization.

Question 1162

Topic: 7. Hand and Wrist
A 14-month-old child presents with a hypoplastic thumb. Examination reveals absent thenar musculature, an adducted first web space, and an unstable carpometacarpal joint. Radiographs show partial absence of the first metacarpal base. What is the most appropriate surgical management?
. Opponensplasty and web space deepening
. First web space release and metacarpophalangeal joint stabilization
. Index finger pollicization
. Distal radius distraction osteogenesis
. Free toe-to-hand transfer

Correct Answer & Explanation

. Index finger pollicization

Explanation

This patient has Blauth Type IIIB thumb hypoplasia, characterized by the absence of a stable carpometacarpal (CMC) joint. Due to the lack of basal stability, reconstruction of the existing digit is not viable, making index finger pollicization the treatment of choice.

Question 1163

Topic: 7. Hand and Wrist

The nail unit consists of several specialized structures. Which of the following best describes the primary function and characteristic of the sterile matrix?

. It generates 90% of the nail plate volume.
. It provides adherence to the nail plate and contributes to the ventral nail.
. It forms the protective barrier at the distal fingertip.
. It is located proximal to the lunula and produces the dorsal nail roof.
. It is primarily responsible for the longitudinal growth rate of the nail.

Correct Answer & Explanation

. It provides adherence to the nail plate and contributes to the ventral nail.

Explanation

The sterile matrix lies distal to the lunula, firmly adhering the nail plate to the underlying phalanx and contributing to the ventral layer of the nail plate. The germinal matrix, conversely, is responsible for producing 90% of the nail plate's volume.

Question 1164

Topic: 7. Hand and Wrist

A patient undergoes a revision amputation of the distal phalanx following a severe crush injury. Postoperatively, the patient develops a symptomatic hook nail deformity. Which of the following surgical errors most likely contributed to this complication?

. Failure to repair the germinal matrix
. Inadequate soft tissue coverage leaving the nail bed distally unsupported
. Over-resection of the sterile matrix
. Tight closure of the eponychial fold
. Failure to stent the proximal nail fold

Correct Answer & Explanation

. Inadequate soft tissue coverage leaving the nail bed distally unsupported

Explanation

A hook nail deformity occurs when the nail bed loses its distal bony support, often due to closing volar soft tissue too tightly over an amputated bone end. To prevent this, the distal bone must be shortened adequately, and the nail bed supported without volar tension.

Question 1165

Topic: 7. Hand and Wrist

A 3-year-old child presents with a hypoplastic thumb. Examination reveals a narrowed first web space, hypoplasia of the thenar muscles, and instability of the metacarpophalangeal (MCP) joint, but the carpometacarpal joint is clinically and radiographically stable. Which combination of procedures is most appropriate?

. Index finger pollicization
. First web space deepening, opponensplasty, and MCP joint ulnar collateral ligament reconstruction
. Distal radius distraction and free fibula transfer
. Metacarpal lengthening and flexor digitorum superficialis transfer
. Amputation and toe-to-hand transfer

Correct Answer & Explanation

. First web space deepening, opponensplasty, and MCP joint ulnar collateral ligament reconstruction

Explanation

This is a Blauth Type II thumb hypoplasia, characterized by web space narrowing, thenar hypoplasia, and MCP joint instability with a stable CMC joint. Management consists of reconstructing the deficient elements via web space deepening, opponensplasty, and UCL reconstruction.

Question 1166

Topic: 7. Hand and Wrist

Following the repair of a severe nail bed laceration with proximal avulsion, a stent is placed beneath the eponychial fold. What is the primary purpose of this step?

. To maintain the length of the distal phalanx
. To prevent synechiae formation between the dorsal roof and the germinal matrix
. To compress the sterile matrix graft and prevent hematoma
. To direct the longitudinal growth rate of the new nail plate
. To prevent infection of the distal interphalangeal joint

Correct Answer & Explanation

. To prevent synechiae formation between the dorsal roof and the germinal matrix

Explanation

Stenting the proximal nail fold (eponychium) prevents the dorsal roof from adhering to the underlying germinal matrix (synechiae). Such adhesions can result in a permanently split, ridged, or absent nail plate.

Question 1167

Topic: 7. Hand and Wrist

In an index finger pollicization procedure, the extensor digitorum communis (EDC) and extensor indicis proprius (EIP) tendons are reassigned. The EDC tendon of the index finger is typically sectioned and attached to the base of the new first metacarpal (former proximal phalanx) to function as which muscle?

. Abductor pollicis longus
. Extensor pollicis brevis
. Extensor pollicis longus
. Adductor pollicis
. First dorsal interosseous

Correct Answer & Explanation

. Abductor pollicis longus

Explanation

In pollicization, the EDC is shortened and attached to the base of the proximal phalanx (which becomes the new thumb metacarpal) to function as the abductor pollicis longus (APL). The EIP is typically routed to function as the extensor pollicis longus (EPL).

Question 1168

Topic: 7. Hand and Wrist
What clinical or radiographic finding definitively separates Blauth Type IIIA from Type IIIB congenital thumb hypoplasia, thereby dictating the need for index finger pollicization rather than reconstruction?
. Absence of the flexor pollicis longus tendon
. Narrowing of the first web space with adduction contracture
. Absence of the proximal first metacarpal with carpometacarpal (CMC) joint instability
. Hypoplasia of the thenar intrinsic musculature
. Presence of a pollex abductus connection

Correct Answer & Explanation

. Absence of the proximal first metacarpal with carpometacarpal (CMC) joint instability

Explanation

The critical distinction between Blauth IIIA and IIIB is the stability of the CMC joint. Type IIIA has a stable CMC joint and can be reconstructed, whereas Type IIIB has an absent proximal metacarpal and unstable CMC joint, necessitating index finger pollicization.

Question 1169

Topic: 7. Hand and Wrist

A patient presents with a progressive "hook nail" deformity 6 months after sustaining a distal fingertip amputation. What is the most likely biomechanical cause of this specific deformity?

. Failure to repair a germinal matrix laceration
. Excessive tension applied during nail bed repair
. Loss of distal tuft bony support with the nail bed draped over the closure
. Retained subungual hematoma under the proximal nail fold
. Hypertrophy of the hyponychium

Correct Answer & Explanation

. Loss of distal tuft bony support with the nail bed draped over the closure

Explanation

A hook nail deformity typically occurs when there is a loss of bony support from the distal phalanx tuft, causing the distal nail bed and subsequently the growing nail to curve palmarward over the amputation site.

Question 1170

Topic: 7. Hand and Wrist

When performing an index finger pollicization, preservation of which of the following structures is most critical for the viability of the transferred digit?

. Radial digital nerve of the index finger
. Proper palmar digital arteries of the index finger
. Superficial dorsal venous system
. Princeps pollicis artery
. Dorsal metacarpal arteries

Correct Answer & Explanation

. Proper palmar digital arteries of the index finger

Explanation

The index finger is transferred on its neurovascular pedicles. Preservation and careful mobilization of the proper palmar digital arteries are critical for arterial inflow and viability of the pollicized digit.

Question 1171

Topic: 7. Hand and Wrist

A newborn infant presents with complete absence of the thumb, including all phalanges and the first metacarpal. Based on the Blauth classification, what is the most appropriate definitive management for this deformity?

. Observation and acceptance of the deformity
. Non-vascularized toe-to-hand transfer
. Distraction osteogenesis of the radial carpus
. Index finger pollicization
. Vascularized bone graft from the fibula

Correct Answer & Explanation

. Index finger pollicization

Explanation

Complete absence of the thumb is classified as Blauth Type V. The standard of care for restoring pinch and grasp in this condition is index finger pollicization.

Question 1172

Topic: 7. Hand and Wrist

A patient complains of a chronic longitudinal split in their nail plate following an old crush injury. This specific deformity is most frequently caused by persistent scarring in which of the following structures?

. Germinal matrix
. Sterile matrix
. Eponychial fold
. Hyponychium
. Distal phalanx tuft

Correct Answer & Explanation

. Germinal matrix

Explanation

A longitudinal split in the nail plate is typically the result of an unaddressed scar or defect in the germinal matrix, as this is the tissue responsible for generating the nail plate. Sterile matrix scarring typically causes non-adherence rather than a split.

Question 1173

Topic: 7. Hand and Wrist

A 35-year-old machinist suffers a crush-avulsion injury resulting in complete loss of the eponychial fold and exposure of the proximal nail matrix. What is the most reliable method for reconstructing the eponychial fold to prevent severe future nail deformity?

. Full-thickness skin graft placed directly on the germinal matrix
. Split-thickness skin graft from the thigh
. Local rotational or advancement flaps (e.g., eponychial flap)
. Healing by secondary intention
. Amputation of the distal phalanx

Correct Answer & Explanation

. Local rotational or advancement flaps (e.g., eponychial flap)

Explanation

Skin grafts placed directly on the germinal matrix tend to fail or cause severe scarring. Complete loss of the eponychial fold is best managed with local rotational or advancement flaps from the dorsal finger to provide durable coverage.

Question 1174

Topic: 7. Hand and Wrist

When counseling parents regarding an index finger pollicization for their child's Blauth Type IV thumb hypoplasia, what preoperative factor should be emphasized as the strongest predictor of limited functional outcome in the newly constructed thumb?

. Age less than 12 months at the time of surgery
. Pre-existing stiffness or limited mobility in the index finger
. Absence of the radial artery on ultrasound
. Unilateral rather than bilateral presentation
. Concomitant syndactyly of the ulnar digits

Correct Answer & Explanation

. Pre-existing stiffness or limited mobility in the index finger

Explanation

The functional outcome of pollicization depends heavily on the preoperative mobility of the index finger. A stiff index finger (often termed "pollicizing a stiff finger") will result in a stiff, poorly functioning thumb.

Question 1175

Topic: Hand Trauma & Infection

A patient develops a severe acute paronychia that has progressed to a fluctuant abscess extending completely under the proximal eponychial fold. What is the standard surgical approach to adequately drain this without causing permanent nail deformity?

. Longitudinal incision through the center of the nail plate and underlying bed
. Excision of the entire nail bed down to the periosteum
. Elevation of the eponychial fold and removal of the proximal third of the nail plate
. Distal fingertip pulp incision (fish-mouth approach)
. Trephination of the distal nail plate only

Correct Answer & Explanation

. Elevation of the eponychial fold and removal of the proximal third of the nail plate

Explanation

For an abscess extending under the eponychial fold (eponychia), adequate drainage requires gently elevating the eponychial fold and removing the proximal portion of the nail plate to prevent matrix damage and ensure proper outflow.

Question 1176

Topic: Wrist & Carpus

A 62-year-old female underwent volar plating for a distal radius fracture 8 weeks ago. She now complains of a sudden inability to flex the interphalangeal joint of her thumb. Which of the following is the most likely cause of this complication?

. Prominent screw tips penetrating the dorsal cortex
. Plate placement proximal to the watershed line
. Plate placement distal to the watershed line
. Injury to the anterior interosseous nerve during approach
. Nonunion of the distal radius

Correct Answer & Explanation

. Plate placement distal to the watershed line

Explanation

Placing a volar plate distal to the watershed line of the distal radius creates a prominence that can cause attritional rupture of the flexor pollicis longus (FPL) tendon. The FPL is particularly vulnerable due to its close anatomical relationship to the volar cortex.

Question 1177

Topic: 7. Hand and Wrist

A 5-year-old boy with Duchenne Muscular Dystrophy is noted to have a waddling gait and uses his hands to push off his knees to stand up from the floor. His parents report he frequently falls. These findings are primarily indicative of weakness in which of the following muscle groups?

. Distal forearm and hand intrinsic muscles
. Gastrocnemius-soleus complex
. Proximal hip extensors and quadriceps
. Anterior tibialis and peroneal muscles
. Shoulder abductors and external rotators

Correct Answer & Explanation

. Proximal hip extensors and quadriceps

Explanation

Correct Answer: CThe waddling gait (due to gluteus medius/minimus weakness) and Gower's sign (using hands to 'walk up' legs to stand) are classic early signs of Duchenne Muscular Dystrophy. Gower's sign specifically compensates for weakness in the quadriceps and hip extensors, which are crucial for standing up from a seated or prone position. The waddling gait is a result of proximal hip abductor weakness. Therefore, weakness in the proximal hip extensors and quadriceps is the primary underlying cause of these observed signs.Option A (Distal forearm and hand intrinsic muscles):Weakness in these muscles is not characteristic of the early signs of DMD, which primarily affects proximal muscles.Option B (Gastrocnemius-soleus complex):Weakness or contracture of the gastrocnemius-soleus complex leads to equinus deformity and toe-walking, but not directly to a waddling gait or Gower's sign.Option D (Anterior tibialis and peroneal muscles):Weakness in these muscles would lead to foot drop or other ankle deformities, not the described gait or Gower's sign.Option E (Shoulder abductors and external rotators):While shoulder girdle weakness can occur later in DMD, it is not the primary cause of a waddling gait or Gower's sign, which are lower limb and trunk-related compensatory mechanisms.

Question 1178

Topic: 7. Hand and Wrist

A 30-year-old rock climber suffers a forced extension of his flexed ring finger, rupturing his flexor digitorum profundus (FDP) tendon directly at its insertion on the distal phalanx base. According to the standard flexor tendon injury classification, this corresponds to:

. Zone I
. Zone II
. Zone III
. Zone IV
. Zone V

Correct Answer & Explanation

. Zone I

Explanation

Zone I of the flexor tendon system extends from the insertion of the flexor digitorum superficialis (FDS) to the insertion of the FDP on the distal phalanx. Injuries here isolate the FDP tendon.

Question 1179

Topic: 7. Hand and Wrist

A 40-year-old female presents with aching volar forearm pain and paresthesias in the thumb, index, and middle fingers. The physician is trying to differentiate between carpal tunnel syndrome (CTS) and pronator syndrome. Which clinical finding strongly points toward pronator syndrome rather than CTS?

. Severe nocturnal exacerbation of symptoms
. Positive Phalen test at the wrist
. Paresthesias over the thenar eminence
. Severe atrophy of the abductor pollicis brevis
. Worsening symptoms with neck extension

Correct Answer & Explanation

. Paresthesias over the thenar eminence

Explanation

The palmar cutaneous branch of the median nerve innervates the skin over the thenar eminence. It branches proximal to the carpal tunnel, so it is spared in CTS but affected in more proximal compressions like pronator syndrome.

Question 1180

Topic: 7. Hand and Wrist

Which of the following physical examination maneuvers has the highest sensitivity for diagnosing carpal tunnel syndrome?

. Tinel's sign over the median nerve
. Phalen's test
. Carpal compression test (Durkan's test)
. Semmes-Weinstein monofilament testing
. Froment's sign

Correct Answer & Explanation

. Carpal compression test (Durkan's test)

Explanation

The carpal compression test, or Durkan's test, involves applying direct manual pressure over the carpal tunnel for up to 30 seconds. It is widely considered the most sensitive provocative maneuver for diagnosing carpal tunnel syndrome.

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