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7. Hand and Wrist MCQs

Practice Set 231 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 4601

Topic: Nerve & Tendon
A 25-year-old rugby player is unable to actively flex the distal interphalangeal (DIP) joint of his ring finger after aggressively grabbing an opponent's jersey during a tackle. Ultrasound shows the flexor digitorum profundus (FDP) tendon stump retracted to the level of the lumbrical origin in the palm. According to the Leddy-Packer classification, what type of injury is this and what is the required timeframe for primary repair?
. Type I, requiring repair within 7-10 days
. Type I, safely repairable up to 3-4 weeks
. Type II, requiring repair within 7-10 days
. Type II, safely repairable up to 3-4 weeks
. Type III, requiring repair within 7-10 days

Correct Answer & Explanation

. Type I, requiring repair within 7-10 days

Explanation

This is a Type I Leddy-Packer jersey finger injury. The FDP tendon retracts into the palm (zone III), rupturing both vincula. This severely compromises the tendon's blood supply. To avoid tendon necrosis and contracture, surgical repair must be performed acutely, ideally within 7 to 10 days.

Question 4602

Topic: Nerve & Tendon

A patient presents to the clinic unable to form a perfect 'OK' sign with their thumb and index finger, instead flattening the pinch by using the pulps of the digits. Which nerve is predominantly affected, and which specific muscle function is lost?

. Anterior interosseous nerve; loss of flexor pollicis longus and flexor digitorum profundus to the index finger
. Posterior interosseous nerve; loss of extensor pollicis longus and extensor indicis proprius
. Median nerve at the carpal tunnel; loss of abductor pollicis brevis
. Ulnar nerve at the cubital tunnel; loss of adductor pollicis
. Ulnar nerve in Guyon's canal; loss of the first dorsal interosseous

Correct Answer & Explanation

. Anterior interosseous nerve; loss of flexor pollicis longus and flexor digitorum profundus to the index finger

Explanation

The anterior interosseous nerve (AIN) is a pure motor branch of the median nerve innervating the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index and middle fingers, and the pronator quadratus. Loss of FPL and FDP prevents terminal flexion of the thumb and index finger, leading to a positive 'OK' sign (Kiloh-Nevin sign) where the patient pinches with flattened pulps.

Question 4603

Topic: 7. Hand and Wrist
A 28-year-old carpenter sustains a volar laceration to his index finger over the proximal aspect of the proximal phalanx. Surgical exploration reveals transection of both the FDS and FDP tendons. In what flexor tendon zone did this injury occur?
. Zone I
. Zone II
. Zone III
. Zone IV
. Zone V

Correct Answer & Explanation

. Zone II

Explanation

Zone II (historically called 'no man's land') extends from the proximal aspect of the A1 pulley to the insertion of the FDS on the middle phalanx. Lacerations in this zone frequently involve both the FDS and FDP tendons within the tight fibro-osseous sheath.

Question 4604

Topic: Nerve & Tendon

A patient undergoing a carpal tunnel release subsequently experiences an isolated loss of thumb opposition but retains normal sensation over the thenar eminence and volar aspect of the thumb. Which structure was most likely iatrogenically injured?

. Recurrent motor branch of the median nerve
. Palmar cutaneous 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, superficial head of flexor pollicis brevis). Injury results in loss of opposition. Sensation remains intact because the proper digital nerves and palmar cutaneous branch are spared.

Question 4605

Topic: 7. Hand and Wrist

A 45-year-old male presents with right arm pain and numbness radiating to his thumb and index finger. On examination, he has weakness in wrist extension against resistance and a diminished brachioradialis reflex. Which cervical nerve root is most likely compressed?

. C4
. C5
. C6
. C7
. C8

Correct Answer & Explanation

. C4

Explanation

The C6 nerve root innervates the wrist extensors (extensor carpi radialis longus and brevis) and supplies sensation to the lateral forearm, thumb, and index finger. It also mediates the brachioradialis reflex. C5 is primary for deltoid/biceps, C7 for triceps/wrist flexion, and C8 for finger flexion/intrinsic hand muscles.

Question 4606

Topic: 7. Hand and Wrist

A 24-year-old rugby player felt a 'pop' in his left ring finger while attempting to grab an opponent's jersey. He is unable to actively flex the distal interphalangeal (DIP) joint of the ring finger, but PIP joint flexion is fully intact. Which of the following tendons is injured, and what is its normal anatomic insertion?

. Flexor digitorum superficialis; base of the middle phalanx
. Flexor digitorum profundus; base of the distal phalanx
. Flexor digitorum superficialis; volar plate of the PIP joint
. Flexor digitorum profundus; base of the middle phalanx
. Extensor digitorum communis; base of the distal phalanx

Correct Answer & Explanation

. Flexor digitorum superficialis; base of the middle phalanx

Explanation

The patient has a 'Jersey finger,' which is an avulsion of the flexor digitorum profundus (FDP) tendon. The FDP normally inserts onto the volar base of the distal phalanx and is responsible for active flexion of the DIP joint. The FDS inserts on the middle phalanx and flexes the PIP joint.

Question 4607

Topic: Wrist & Carpus

A 55-year-old female sustains a nondisplaced distal radius fracture treated conservatively in a cast. Six weeks later, following cast removal, she suddenly loses the ability to actively extend her thumb interphalangeal joint. Rupture of which tendon is most likely responsible, and around which bony prominence does it abruptly change direction?

. Extensor pollicis brevis; radial styloid
. Abductor pollicis longus; Lister's tubercle
. Extensor pollicis longus; Lister's tubercle
. Extensor pollicis longus; ulnar styloid
. Extensor indicis proprius; distal radioulnar joint

Correct Answer & Explanation

. Extensor pollicis brevis; radial styloid

Explanation

Delayed rupture of the Extensor Pollicis Longus (EPL) tendon is a classic complication of nondisplaced distal radius fractures due to ischemia or mechanical attrition. The EPL courses through the third extensor compartment and changes direction around Lister's tubercle on the dorsal radius.

Question 4608

Topic: 7. Hand and Wrist

A 21-year-old man falls onto his outstretched hand and sustains a fracture through the proximal pole of the scaphoid. He is counseled on the high risk for avascular necrosis (AVN). This risk is primarily due to the retrograde blood supply to the proximal pole. What is the major vascular source of this blood supply?

. Superficial palmar arch
. Dorsal carpal branch of the radial artery
. Deep palmar arch
. Ulnar artery
. Anterior interosseous artery

Correct Answer & Explanation

. Superficial palmar arch

Explanation

The primary blood supply to the scaphoid is derived from the dorsal carpal branch of the radial artery. The vessels enter the scaphoid at the dorsal ridge near the waist and distal pole, providing retrograde blood flow to the proximal pole. A fracture at the proximal pole disrupts this supply, significantly increasing the risk of nonunion and AVN.

Question 4609

Topic: 7. Hand and Wrist
A 32-year-old manual laborer presents with progressive dorsal wrist pain. Radiographs demonstrate sclerosis and fragmentation of the lunate with a fixed scaphoid rotary subluxation. The radioscaphoid angle is 70 degrees. Ulnar variance is neutral. According to the Lichtman classification, what is the most appropriate surgical treatment?
. Radial shortening osteotomy
. Proximal row carpectomy
. Vascularized bone graft from the distal radius
. Scaphoid-trapezium-trapezoid (STT) fusion
. Distal radius core decompression

Correct Answer & Explanation

. Proximal row carpectomy

Explanation

The patient has Lichtman Stage IIIB Kienbock's disease, defined by lunate fragmentation and collapse with fixed scaphoid rotation (carpal instability). Joint-leveling procedures (radial shortening) or revascularization are better suited for Stages II or IIIA (prior to carpal collapse/scaphoid rotation). For Stage IIIB without diffuse secondary arthrosis, proximal row carpectomy or scaphocapitate fusion are standard options.

Question 4610

Topic: 7. Hand and Wrist

During the repair of a Zone II flexor tendon injury, the surgeon must carefully navigate the relationship between the flexor digitorum superficialis (FDS) and the flexor digitorum profundus (FDP). The FDP tendon passes through Camper's chiasm, which is formed by the bifurcation of the FDS tendon. At approximately what anatomical landmark does this decussation occur?

. Metacarpal neck
. Proximal aspect of the proximal phalanx
. Proximal aspect of the middle phalanx
. Distal aspect of the middle phalanx
. Distal to the A4 pulley

Correct Answer & Explanation

. Metacarpal neck

Explanation

Camper's chiasm is the anatomical structure where the FDS tendon bifurcates, allowing the FDP tendon to pass from a deep to a superficial position. This decussation occurs over the proximal aspect of the proximal phalanx, typically deep to the A2 pulley.

Question 4611

Topic: Wrist & Carpus

A 65-year-old female presents 6 weeks after non-operative management of a minimally displaced distal radius fracture. She reports the sudden inability to extend her thumb. Examination reveals a complete lack of active retropulsion of the thumb. An Extensor Pollicis Longus (EPL) rupture is diagnosed. What is the most common anatomic zone implicated in this specific late complication?

. The first dorsal compartment
. Lister's tubercle at the third dorsal compartment
. The intersection syndrome area
. The scapholunate interval
. The extensor retinaculum at the fifth dorsal compartment

Correct Answer & Explanation

. The first dorsal compartment

Explanation

EPL rupture is a classic complication following nondisplaced or minimally displaced distal radius fractures. The rupture typically occurs at Lister's tubercle (the third dorsal compartment). The pathophysiology involves a combination of mechanical attrition against the intact or slightly irregular tubercle and localized ischemia within the intact retinaculum affecting the tendon's watershed zone.

Question 4612

Topic: 7. Hand and Wrist
A patient sustains a deep laceration to the volar aspect of the proximal phalanx, severing both the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons. According to the Verdan classification, this injury occurs in which flexor tendon zone?
. Zone I
. Zone II
. Zone III
. Zone IV
. Zone V

Correct Answer & Explanation

. Zone II

Explanation

Zone II (historically called "no man's land") extends from the A1 pulley (distal palmar crease) to the FDS insertion at the middle phalanx. It is characterized by the presence of both FDS and FDP tendons within a tight fibro-osseous sheath.

Question 4613

Topic: Nerve & Tendon

What is the most common long-term complication associated with an un-united pediatric lateral condyle humerus fracture?

. Cubitus varus
. Tardy ulnar nerve palsy
. Volkmann ischemic contracture
. Radial head subluxation
. Median nerve palsy

Correct Answer & Explanation

. Cubitus varus

Explanation

Nonunion of a lateral condyle fracture typically leads to a progressive cubitus valgus deformity due to proximal migration of the lateral condyle. Over years or decades, this significant valgus alignment stretches the ulnar nerve behind the medial epicondyle, resulting in tardy ulnar nerve palsy.

Question 4614

Topic: Nerve & Tendon

A 10-year-old child presents with a progressive elbow deformity and numbness in the small finger. History reveals a conservatively managed lateral condyle fracture at age 4. What is the most likely structural deformity and the associated nerve palsy?

. Cubitus varus leading to radial nerve palsy
. Cubitus valgus leading to tardy ulnar nerve palsy
. Cubitus varus leading to tardy ulnar nerve palsy
. Cubitus valgus leading to anterior interosseous nerve palsy
. Cubitus valgus leading to median nerve palsy

Correct Answer & Explanation

. Cubitus varus leading to radial nerve palsy

Explanation

Nonunion or premature lateral growth arrest following a lateral condyle fracture classically leads to a progressive cubitus valgus deformity. Over time, this valgus angulation stretches the ulnar nerve within the cubital tunnel, resulting in a tardy ulnar nerve palsy.

Question 4615

Topic: Nerve & Tendon

A 6-year-old boy presents with a supracondylar humerus fracture that is posterolaterally displaced. On clinical examination, he is unable to flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. Which nerve is most likely injured?

. Ulnar nerve
. Radial nerve
. Anterior interosseous nerve
. Posterior interosseous nerve
. Musculocutaneous nerve

Correct Answer & Explanation

. Ulnar nerve

Explanation

The anterior interosseous nerve (AIN) is a branch of the median nerve and is the most commonly injured nerve in extension-type, posterolaterally displaced supracondylar fractures. It provides motor innervation to the flexor pollicis longus and flexor digitorum profundus to the index and middle fingers.

Question 4616

Topic: Nerve & Tendon

A 4-year-old boy sustains a lateral condyle fracture of the humerus. Radiographs show 3 mm of displacement. The fracture is treated with closed reduction and percutaneous pinning. What is the most common long-term complication if this fracture fails to unite (non-union)?

. Cubitus varus and median nerve palsy
. Cubitus valgus and tardy ulnar nerve palsy
. Volkmann ischemic contracture
. Radial head subluxation
. Myositis ossificans

Correct Answer & Explanation

. Cubitus varus and median nerve palsy

Explanation

Lateral condyle non-unions characteristically lead to progressive cubitus valgus deformity. Over time, the valgus angulation stretches the ulnar nerve, resulting in a tardy ulnar nerve palsy.

Question 4617

Topic: Nerve & Tendon

A 6-year-old child sustains a minimally displaced lateral condyle fracture of the humerus. Which of the following is the most common long-term complication if this injury goes unrecognized and untreated?

. Cubitus varus
. Tardy ulnar nerve palsy
. Radial head subluxation
. Avascular necrosis of the trochlea
. Median nerve palsy

Correct Answer & Explanation

. Cubitus varus

Explanation

Untreated lateral condyle fractures often lead to nonunion and progressive cubitus valgus. This valgus deformity progressively stretches the ulnar nerve, leading to tardy ulnar nerve palsy years later.

Question 4618

Topic: Wrist & Carpus

A randomized controlled trial comparing two surgical techniques for distal radius fractures concludes there is no significant difference in functional outcomes at 1 year. However, true population data dictates that a significant difference does exist. The investigators committed a Type II error. Which of the following is equal to the probability of avoiding this error?

. Alpha
. p-value
. Statistical power
. Positive predictive value
. Confidence interval

Correct Answer & Explanation

. Statistical power

Explanation

A Type II error (beta) is failing to reject the null hypothesis when it is actually false. The probability of avoiding a Type II error is Statistical Power (1 - beta). Power is the ability of a study to detect a true difference if one exists.

Question 4619

Topic: Nerve & Tendon

Following a closed crush injury to the forearm, a patient exhibits a complete motor and sensory deficit in the distribution of the median nerve. Nerve conduction studies later indicate a Sunderland third-degree nerve injury. This classification signifies the disruption of the axon, the myelin sheath, and which other distinct neural structure?

. No other structures (axon and myelin only)
. Epineurium
. Perineurium
. Endoneurium
. Complete transection of all neural elements

Correct Answer & Explanation

. Perineurium

Explanation

In the Sunderland classification of peripheral nerve injuries: First-degree = focal demyelination (Neuropraxia); Second-degree = axonal damage with intact endoneurium (Axonotmesis); Third-degree = loss of axonal and endoneurial continuity, but intact perineurium and epineurium; Fourth-degree = disruption of axon, endoneurium, and perineurium with intact epineurium; Fifth-degree = complete nerve transection (Neurotmesis).

Question 4620

Topic: 7. Hand and Wrist

A 28-year-old carpenter sustains a laceration to the volar aspect of his index finger. Exploration reveals a complete laceration of both the flexor digitorum superficialis (FDS) and profundus (FDP) tendons. The injury is classified as occurring in Zone II. What are the anatomical boundaries of flexor tendon Zone II in the digits?

. From the distal interphalangeal joint to the FDP insertion
. From the distal palmar crease to the FDS insertion
. From the carpal tunnel to the distal palmar crease
. From the musculotendinous junction to the carpal tunnel
. From the FDS insertion to the FDP insertion

Correct Answer & Explanation

. From the distal palmar crease to the FDS insertion

Explanation

Flexor tendon Zone II, historically termed 'no man's land' due to the difficulty of successful repair, extends from the A1 pulley (at the level of the distal palmar crease) to the insertion of the FDS tendon on the middle phalanx. In this zone, both the FDS and FDP tendons are tightly enclosed within the flexor tendon sheath.

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