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7. Hand and Wrist MCQs

Practice Set 244 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 4861

Topic: 7. Hand and Wrist

A 22-year-old male falls onto an outstretched hand and sustains a proximal pole scaphoid fracture. Which of the following anatomical features best explains the high rate of avascular necrosis (AVN) and nonunion associated with fractures in this specific region of the carpus?

. The proximal pole is entirely covered in articular cartilage, preventing callus formation.
. Blood supply enters the distal scaphoid and flows retrograde to the proximal pole.
. The proximal pole relies on a robust volar arterial network that is easily torn.
. The radiocarpal ligaments firmly attach to the proximal pole, causing constant distraction.
. The deep branch of the radial artery bypasses the scaphoid completely.

Correct Answer & Explanation

. Blood supply enters the distal scaphoid and flows retrograde to the proximal pole.

Explanation

The scaphoid bone is supplied primarily by branches of the radial artery (the dorsal carpal branch), which enter the bone at the distal third and waist. The blood supply then flows in a retrograde fashion to perfuse the proximal pole. Fractures through the waist or proximal pole routinely disrupt this retrograde blood flow, leading to a high risk of avascular necrosis and nonunion of the proximal fragment.

Question 4862

Topic: 7. Hand and Wrist

A 24-year-old man presents with chronic wrist pain and weakness following a fall onto an outstretched hand 6 months ago. The corresponding MRI reveals findings consistent with avascular necrosis (AVN) of the carpal bone shown. The blood supply to the proximal pole of this bone primarily enters via which of the following structures?

. Volar radiocarpal ligaments
. Dorsal carpal branch of the radial artery
. Superficial palmar arch
. Anterior interosseous artery
. Ulnar artery deep branch

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery

Explanation

The scaphoid relies heavily on retrograde blood flow. The dorsal carpal branch of the radial artery enters the scaphoid at the dorsal ridge (distal to the waist) and supplies the proximal 80% of the bone. Fractures at the waist or proximal pole disrupt this retrograde supply, leading to a high risk of AVN.

Question 4863

Topic: 7. Hand and Wrist

Following a primary Zone II flexor tendon repair in the hand, the patient is started on an early active motion protocol. Which of the following technical factors has the greatest impact on the tensile strength of the repair and its resistance to gap formation during early active motion?

. The type of locking knot tied
. The number of core suture strands crossing the repair site
. The use of a running epitendinous suture
. The caliber of the core suture material
. The timing of surgery within 24 hours of injury

Correct Answer & Explanation

. The number of core suture strands crossing the repair site

Explanation

The ultimate tensile strength of a flexor tendon repair is directly proportional to the number of core suture strands crossing the repair site. Modern early active motion protocols typically require a 4-strand or 6-strand repair to safely withstand the required mechanical loads without early gapping or rupture.

Question 4864

Topic: Wrist & Carpus

A patient treated with a volar locking plate for a distal radius fracture 3 months ago now presents with the inability to actively flex the interphalangeal joint of the thumb. Which of the following technical errors during the index surgery is the most likely cause of this complication?

. Prominent dorsal screw penetration into the extensor compartments
. Placement of the volar plate distal to the watershed line
. Inadequate reduction of the Lister tubercle
. Failure to release the brachioradialis insertion during the approach
. Use of excessively long peg screws in the distal row

Correct Answer & Explanation

. Placement of the volar plate distal to the watershed line

Explanation

Flexor pollicis longus (FPL) tendon rupture is a well-known complication of volar plating for distal radius fractures. It is classically caused by attrition/friction against a prominent plate placed too distally, crossing the 'watershed line' and impinging directly on the volar flexor tendons.

Question 4865

Topic: 7. Hand and Wrist

A patient with severe right hip osteoarthritis is advised by his physical therapist to use a cane during ambulation to relieve pain.

When the cane is properly held in the contralateral (left) hand, which of the following best explains the biomechanical mechanism by which the joint reaction force across the right hip is reduced?

. It shifts the body's center of gravity laterally away from the affected hip
. It increases the lever arm of the hip abductor musculature
. It creates an external support moment that reduces the force required by the hip abductors
. It decreases the lever arm of the body weight relative to the center of the femoral head
. It directly increases the joint reaction force to improve joint congruency

Correct Answer & Explanation

. It creates an external support moment that reduces the force required by the hip abductors

Explanation

Holding a cane in the contralateral hand provides a ground reaction force at a large distance from the affected hip center. This creates a substantial counter-moment that opposes the turning moment of the body weight. Because the external support moment generated by the cane assists in leveling the pelvis, the force required by the hip abductors is significantly decreased. Since abductor muscle force is the largest contributor to the hip joint reaction force, decreasing it leads to a dramatic reduction in the overall load across the joint.

Question 4866

Topic: 7. Hand and Wrist

A 6-month-old infant presents with complete, simple syndactyly of the long and ring fingers of the right hand. When discussing surgical release, what is the ideal timing and the most critical technical consideration to prevent web creep?

. Release at 6 months of age; use of full-thickness skin grafts
. Release at 12-18 months of age; creation of a dorsal rectangular or triangular flap
. Release at 3 years of age; creation of a volar zig-zag flap
. Release at 6 months of age; primary closure under tension
. Release at 4 years of age; use of split-thickness skin grafts

Correct Answer & Explanation

. Release at 12-18 months of age; creation of a dorsal rectangular or triangular flap

Explanation

Simple syndactyly release is typically performed between 12 and 18 months of age, before the development of fine motor pinch skills. Border digits (thumb-index or ring-small) are released earlier (around 6 months) to prevent angular deformity. To reconstruct the web space and prevent distal migration (web creep), a dorsal rectangular or triangular flap is typically utilized, along with full-thickness skin grafts for the exposed sides of the digits.

Question 4867

Topic: 7. Hand and Wrist

In Zone II flexor tendon injuries ('No Man\'s Land'), the flexor digitorum superficialis (FDS) tendon splits to allow passage of the flexor digitorum profundus (FDP) tendon. What is the specific anatomical term for this decussation of the FDS?

. Vincula brevia
. Camper's chiasm
. A1 pulley
. Cleland's ligament
. Grayson's ligament

Correct Answer & Explanation

. Camper's chiasm

Explanation

Camper's chiasm is the anatomical structure where the FDS tendon bifurcates and reunites dorsal to the FDP tendon, allowing the FDP to pass through and insert on the distal phalanx. This complex anatomy occurs in Zone II of the flexor tendon system.

Question 4868

Topic: Nerve & Tendon

A patient with severe carpal tunnel syndrome exhibits weakness in thumb opposition. Which muscle is primarily responsible for this action, and which specific nerve branch innervates it?

. Abductor pollicis longus; Posterior interosseous nerve
. Adductor pollicis; Deep branch of the ulnar nerve
. Opponens pollicis; Recurrent motor branch of the median nerve
. Flexor pollicis brevis (deep head); Deep branch of the ulnar nerve
. First dorsal interosseous; Deep branch of the ulnar nerve

Correct Answer & Explanation

. Opponens pollicis; Recurrent motor branch of the median nerve

Explanation

The opponens pollicis, along with the abductor pollicis brevis and the superficial head of the flexor pollicis brevis, comprises the thenar eminence. These are innervated by the recurrent motor branch of the median nerve, which can be compressed in severe carpal tunnel syndrome, leading to atrophy and weakness in thumb opposition.

Question 4869

Topic: Nerve & Tendon

A patient suffers a proximal median nerve laceration but retains unexpected intrinsic hand muscle function. This is most likely due to a Martin-Gruber anastomosis. What does this anomaly connect?

. Median nerve to the ulnar nerve in the forearm
. Ulnar nerve to the median nerve in the forearm
. Median nerve to the ulnar nerve in the palm
. Ulnar nerve to the median nerve in the palm
. Radial nerve to the median nerve in the forearm

Correct Answer & Explanation

. Median nerve to the ulnar nerve in the forearm

Explanation

The Martin-Gruber anastomosis is an anomalous motor nerve connection from the median nerve (or anterior interosseous nerve) to the ulnar nerve in the forearm. It can cause atypical clinical presentations following isolated nerve injuries.

Question 4870

Topic: Nerve & Tendon

During the repair of a complete Zone II flexor tendon laceration in the index finger, preservation of specific pulleys is vital to maintain mechanical advantage and prevent bowstringing. Biomechanically, which pulley is the most critical to preserve or reconstruct?

. 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 of the flexor tendons. Of the two, the A2 pulley, located over the proximal phalanx, is the most biomechanically important.

Question 4871

Topic: Nerve & Tendon

A 45-year-old female undergoes an open carpal tunnel release. Postoperatively, her paresthesias resolve, but she presents 4 weeks later with a profound inability to palmar abduct her thumb. Which of the following structures was most likely injured iatrogenically during the procedure?

. Palmar cutaneous branch of the median nerve
. Recurrent motor branch of the median nerve
. Deep motor branch of the ulnar nerve
. Superficial radial nerve
. Anterior interosseous nerve

Correct Answer & Explanation

. Recurrent motor branch of the median nerve

Explanation

The recurrent motor branch of the median nerve innervates the thenar musculature (abductor pollicis brevis, opponens pollicis, and superficial head of the flexor pollicis brevis). Injury results in weakness of thumb palmar abduction and opposition.

Question 4872

Topic: 7. Hand and Wrist

A 45-year-old female presents with numbness in the thumb, index, and middle fingers, and night pain. Nerve conduction studies (NCS) are ordered. Which of the following is typically the earliest and most sensitive electrodiagnostic finding in this condition?

. Decreased motor amplitude
. Prolonged sensory latency
. Prolonged motor latency
. Fibrillation potentials on EMG
. Slowed nerve conduction velocity in the forearm

Correct Answer & Explanation

. Prolonged sensory latency

Explanation

In compressive neuropathies such as carpal tunnel syndrome, the large myelinated sensory fibers are typically affected before the motor fibers. Consequently, a prolonged sensory distal latency or decreased sensory conduction velocity across the carpal tunnel is the earliest and most sensitive NCS finding.

Question 4873

Topic: Wrist & Carpus

A surgeon is performing a closed reduction of a distal radius fracture under a hematoma block. What is the generally accepted maximum safe dose of lidocaine without epinephrine for local infiltration in an adult patient?

. 2.0 mg/kg
. 4.5 mg/kg
. 7.0 mg/kg
. 10.0 mg/kg
. 15.0 mg/kg

Correct Answer & Explanation

. 4.5 mg/kg

Explanation

The maximum safe dose of 1% lidocaine without epinephrine for local infiltration is 4.5 mg/kg (up to approximately 300 mg total in an average adult). The addition of epinephrine increases the maximum safe dose to 7.0 mg/kg.

Question 4874

Topic: Wrist & Carpus
A 55-year-old male presents with severe wrist pain and is diagnosed with Stage III Scapholunate Advanced Collapse (SLAC). The surgeon is debating between a proximal row carpectomy (PRC) and a four-corner fusion. Which of the following findings is an absolute contraindication to performing a proximal row carpectomy?
. A scapholunate interval greater than 3 mm
. Severe degeneration of the proximal capitate articular surface
. Radioscaphoid arthritis involving the radial styloid
. Ulnar positive variance
. An intact radioscaphocapitate ligament

Correct Answer & Explanation

. Severe degeneration of the proximal capitate articular surface

Explanation

Proximal row carpectomy (PRC) relies on a healthy articulation between the head of the capitate and the lunate fossa of the distal radius. Therefore, significant degenerative arthritis of the proximal capitate articular surface (capitolunate arthritis) is a strict contraindication to a PRC. In such cases, a four-corner fusion with scaphoid excision is the preferred motion-preserving alternative.

Question 4875

Topic: Nerve & Tendon
A 35-year-old man underwent primary repair of a zone III flexor digitorum profundus (FDP) laceration. Postoperatively, he notes that when he attempts to forcefully flex his fingers into a full fist, the PIP joint of the affected finger paradoxically extends. What is the most likely cause of this phenomenon?
. Rupture of the FDP tendon proximal to the lumbrical origin
. FDS tendon adhesion to the A2 pulley
. A tight FDP tendon repair causing a tenodesis effect
. Attenuation of the central slip
. Rupture of the sagittal band

Correct Answer & Explanation

. Rupture of the FDP tendon proximal to the lumbrical origin

Explanation

This patient is demonstrating a 'lumbrical plus' finger. This occurs when the FDP tendon is divided or ruptures distal to the origin of the lumbrical muscle, or if an FDP graft is left too long. When the patient attempts to flex the finger, the proximal retraction of the FDP pulls the lumbrical muscle proximally, which translates force through the lateral bands to cause paradoxical extension of the PIP and DIP joints.

Question 4876

Topic: 7. Hand and Wrist

A patient with a traumatic ulnar nerve transection at the wrist (low ulnar nerve injury) demonstrates significantly more severe clawing of the ring and small fingers compared to a patient with an ulnar nerve transection at the elbow (high ulnar nerve injury). Which intact muscle is responsible for exacerbating the claw deformity in the low ulnar nerve injury?

. Extensor digitorum communis
. Flexor digitorum superficialis
. Flexor digitorum profundus
. Lumbricals
. Dorsal interossei

Correct Answer & Explanation

. Flexor digitorum profundus

Explanation

This describes the 'Ulnar Paradox.' In a high ulnar nerve injury, the flexor digitorum profundus (FDP) to the ring and small fingers is denervated, so there is less active flexion force at the DIP joint. In a low ulnar nerve injury, the FDP remains innervated (by branches given off in the proximal forearm), leading to unopposed flexion of the DIP joints, which drastically accentuates the classic claw hand posture.

Question 4877

Topic: 7. Hand and Wrist

During a partial fasciectomy for severe Dupuytren's contracture of the ring finger, the surgeon notes that the digital neurovascular bundle is displaced superficially and toward the midline of the digit. Involvement of which of the following fascial cords is the primary cause of this specific anatomical distortion?

. Central cord
. Lateral cord
. Spiral cord
. Natatory cord
. Retrovascular cord

Correct Answer & Explanation

. Spiral cord

Explanation

The spiral cord is responsible for proximal interphalangeal (PIP) joint contractures and classically displaces the digital neurovascular bundle centrally, superficially, and proximally. This distortion places the neurovascular bundle at high risk of iatrogenic injury during surgical excision. The spiral cord is formed by the pretendinous band, spiral band, lateral digital sheet, and Grayson's ligament.

Question 4878

Topic: 7. Hand and Wrist

A 28-year-old man sustains a severe laceration at the level of the proximal wrist crease, completely transecting the median nerve. Six months later, despite complete absence of median nerve sensation in the hand, he demonstrates surprisingly preserved strength in thumb opposition and a normal thenar eminence. Which of the following neural anomalies best explains this physical finding?

. Martin-Gruber anastomosis
. Riche-Cannieu anastomosis
. Berrettini anastomosis
. Marinacci anastomosis
. Bouvier's anomaly

Correct Answer & Explanation

. Riche-Cannieu anastomosis

Explanation

The Riche-Cannieu anastomosis is an anomalous neural connection between the deep branch of the ulnar nerve and the recurrent motor branch of the median nerve in the palm. When present, it allows ulnar nerve innervation of the thenar muscles, preserving thumb opposition even if the median nerve is transected proximal to the wrist. The Martin-Gruber anastomosis occurs in the forearm.

Question 4879

Topic: 7. Hand and Wrist

In the pathogenesis of primary osteoarthritis of the trapeziometacarpal (thumb CMC) joint, attenuation of which specific ligament is classically considered the primary initiating event leading to dorsal-radial subluxation of the metacarpal base?

. Dorsoradial ligament
. Anterior oblique ligament (beak ligament)
. Intermetacarpal ligament
. Posterior oblique ligament
. Ulnar collateral ligament

Correct Answer & Explanation

. Anterior oblique ligament (beak ligament)

Explanation

The anterior oblique ligament (AOL), also known as the beak ligament, originates on the palmar tubercle of the trapezium and inserts on the palmar beak of the first metacarpal. It has historically been considered the primary static stabilizer of the trapeziometacarpal joint. Attenuation of the AOL allows dorsal-radial subluxation of the metacarpal base, accelerating joint degeneration.

Question 4880

Topic: 7. Hand and Wrist

A 24-year-old gymnast presents with chronic ulnar-sided wrist pain after a twisting injury. MRI arthrography reveals a tear of the triangular fibrocartilage complex (TFCC) directly at its radial attachment to the sigmoid notch of the radius. According to the Palmer classification system, how is this tear classified?

. Palmer Class 1A
. Palmer Class 1B
. Palmer Class 1C
. Palmer Class 1D
. Palmer Class 2C

Correct Answer & Explanation

. Palmer Class 1A

Explanation

The Palmer classification categorizes TFCC tears into traumatic (Class 1) and degenerative (Class 2). Palmer 1A is a central perforation; 1B is an ulnar avulsion (with or without ulnar styloid fracture); 1C is a distal avulsion (involving the ulnocarpal ligaments); and 1D is a radial avulsion from the sigmoid notch of the radius.

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