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7. Hand and Wrist MCQs

Practice Set 222 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 4421

Topic: 7. Hand and Wrist

During intraoperative fluoroscopy for closed reduction of a distal radius fracture, how should the C-arm be positioned relative to the operating table to minimize radiation exposure from scatter to the surgeon's head, neck, and hands?

. X-ray tube above the table, image intensifier below the table
. X-ray tube below the table, image intensifier above the table
. Both tube and intensifier lateral to the table
. Position of the tube does not affect scatter radiation distribution
. X-ray tube adjacent to the surgeon's dominant hand

Correct Answer & Explanation

. X-ray tube above the table, image intensifier below the table

Explanation

Radiation scatters primarily backward toward the X-ray tube source after hitting the patient (the largest source of scatter). Positioning the X-ray tube below the table directs the highest intensity scatter toward the floor and surgeon's legs, away from more sensitive and less protected areas like the head, neck, and hands. The image intensifier should be placed above the table.

Question 4422

Topic: Wrist & Carpus

Complex Regional Pain Syndrome (CRPS) is a devastating complication following distal radius fractures. Based on prospective randomized controlled trials, which of the following oral supplements has been recommended to be taken daily for 50 days to decrease the incidence of CRPS?

. Vitamin B6 (Pyridoxine) 100 mg
. Vitamin C (Ascorbic acid) 500 mg
. Vitamin D3 (Cholecalciferol) 2000 IU
. Calcium carbonate 1000 mg
. Glucosamine sulfate 1500 mg

Correct Answer & Explanation

. Vitamin B6 (Pyridoxine) 100 mg

Explanation

Multiple studies (most notably Zollinger et al.) have demonstrated that administering Vitamin C (500 mg daily for 50 days) after a distal radius fracture significantly reduces the risk of developing Complex Regional Pain Syndrome (CRPS), likely through its role as an antioxidant scavenging free radicals.

Question 4423

Topic: 7. Hand and Wrist

A patient presents with weakness in pinching, unable to form a perfect 'O' with the thumb and index finger (positive OK sign). Sensory examination of the hand is completely normal. Compression of which nerve is most likely responsible?

. Ulnar nerve at Guyon's canal
. Median nerve at the carpal tunnel
. Anterior interosseous nerve at the pronator teres
. Posterior interosseous nerve at the arcade of Frohse
. Superficial radial nerve at the brachioradialis

Correct Answer & Explanation

. Ulnar nerve at Guyon's canal

Explanation

The Anterior Interosseous Nerve (AIN) is a pure motor branch of the median nerve. It innervates the flexor pollicis longus (FPL), the flexor digitorum profundus (FDP) to the index and middle fingers, and the pronator quadratus. Weakness of the FPL and index FDP prevents terminal flexion, leading to a collapsed 'pinch' or abnormal OK sign.

Question 4424

Topic: Wrist & Carpus

Following closed reduction and casting of a distal radius fracture, which of the following pharmacological interventions has been supported by randomized controlled trials as an effective prophylactic measure to reduce the incidence of Complex Regional Pain Syndrome (CRPS)?

. Daily administration of Vitamin C 500 mg
. Immediate initiation of an oral corticosteroid taper
. Prophylactic gabapentin 300 mg three times daily
. Application of a topical lidocaine patch
. Early administration of a stellate ganglion block

Correct Answer & Explanation

. Daily administration of Vitamin C 500 mg

Explanation

Multiple studies, including randomized controlled trials, have demonstrated that the administration of Vitamin C (typically 500 mg daily for 50 days) following a distal radius fracture significantly reduces the risk of developing CRPS type I.

Question 4425

Topic: Nerve & Tendon

During Ulnar Collateral Ligament (UCL) reconstruction using the docking technique, which structure is at greatest risk of iatrogenic injury during the splitting of the flexor pronator mass and exposure of the sublime tubercle?

. Median nerve
. Radial nerve
. Medial antebrachial cutaneous nerve
. Ulnar nerve
. Anterior interosseous nerve

Correct Answer & Explanation

. Median nerve

Explanation

The medial antebrachial cutaneous (MABC) nerve branches extensively over the medial elbow. Its posterior branch often crosses directly over the area where the flexor-pronator split is performed to expose the sublime tubercle during UCL reconstruction. Careful blunt dissection and nerve retraction are essential to prevent painful neuromas or numbness.

Question 4426

Topic: 7. Hand and Wrist

A 45-year-old weightlifter undergoes a single-incision anterior approach for a distal biceps tendon repair. Postoperatively, he presents with inability to extend his fingers and thumb, but normal wrist extension with radial deviation. Which nerve was most likely injured during the procedure?

. Lateral antebrachial cutaneous nerve
. Median nerve
. Ulnar nerve
. Posterior interosseous nerve
. Superficial radial nerve

Correct Answer & Explanation

. Lateral antebrachial cutaneous nerve

Explanation

The posterior interosseous nerve (PIN) is at risk during a single-incision anterior approach for distal biceps repair if retractors are placed improperly on the radial neck. Injury to the PIN results in loss of digit extension (ECDC) and thumb extension (EPL), but wrist extension is preserved albeit with radial deviation because ECRL (innervated by the radial nerve proper) is intact, whereas ECU (innervated by PIN) is paralyzed.

Question 4427

Topic: Nerve & Tendon

A 40-year-old male sustains an acute distal biceps tendon rupture while lifting a heavy object. He undergoes surgical repair utilizing a single-incision anterior approach. Which nerve is most at risk of injury during this specific surgical approach?

. Median nerve
. Posterior interosseous nerve (PIN)
. Anterior interosseous nerve (AIN)
. Lateral antebrachial cutaneous nerve (LABCN)
. Ulnar nerve

Correct Answer & Explanation

. Median nerve

Explanation

The lateral antebrachial cutaneous nerve (LABCN), a continuation of the musculocutaneous nerve, is the most commonly injured nerve during a single-incision anterior approach for distal biceps repair. Injury to the Posterior Interosseous Nerve (PIN) is classically associated with the two-incision approach if the forearm is not kept in full supination during the posterior dissection.

Question 4428

Topic: Nerve & Tendon

During a Tommy John procedure (Ulnar Collateral Ligament reconstruction) using a modified Jobe technique with submuscular ulnar nerve transposition in a 20-year-old collegiate pitcher, what fascial structure must be released distally to prevent postoperative ulnar nerve compression?

. Arcade of Struthers
. Osborne's ligament
. Medial intermuscular septum
. Flexor carpi ulnaris (FCU) aponeurosis
. Lacertus fibrosus

Correct Answer & Explanation

. Arcade of Struthers

Explanation

When performing a submuscular transposition of the ulnar nerve, it is critical to release potential sites of compression. Proximally, the medial intermuscular septum and the Arcade of Struthers must be resected. Distally, the deep flexor-pronator aponeurosis (fascia of the FCU) must be released as the nerve enters the two heads of the FCU to prevent distal kinking or compression.

Question 4429

Topic: 7. Hand and Wrist

A 24-year-old American football running back sustains a hyper-dorsiflexion injury to his first metatarsophalangeal (MTP) joint on an artificial turf field. He is diagnosed with a severe 'turf toe' injury. Which anatomic structure is the primary plantar restraint to dorsal subluxation of the proximal phalanx at the first MTP joint?

. Extensor hallucis brevis tendon
. Dorsal capsule
. Plantar plate complex
. Deep transverse metatarsal ligament
. Medial collateral ligament of the MTP joint

Correct Answer & Explanation

. Extensor hallucis brevis tendon

Explanation

Turf toe is a sprain of the first MTP joint, typically caused by forced hyper-dorsiflexion. The plantar plate complex (which includes the plantar plate proper, the sesamoids, and the flexor hallucis brevis tendons) is the primary static and dynamic restraint preventing dorsal subluxation of the proximal phalanx.

Question 4430

Topic: Nerve & Tendon

A 45-year-old male presents with severe cubital tunnel syndrome that has failed conservative management. During an in situ ulnar nerve decompression, which of the following structures forms the anatomic roof of the cubital tunnel and must be released?

. Struthers ligament
. Osborne's ligament
. Lacertus fibrosus
. Arcade of Frohse
. Annular ligament

Correct Answer & Explanation

. Struthers ligament

Explanation

Osborne's ligament (also known as the cubital tunnel retinaculum or arcuate ligament) spans between the olecranon and the medial epicondyle, bridging the two heads of the flexor carpi ulnaris (FCU). It forms the roof of the cubital tunnel and is a primary site of ulnar nerve compression.

Question 4431

Topic: Nerve & Tendon

A 55-year-old male presents with numbness in his small and ring fingers and intrinsic muscle weakness. Electrodiagnostic studies confirm severe ulnar neuropathy at the elbow. During an open surgical release, which structure forms the primary roof of the cubital tunnel?

. Struthers ligament
. Medial intermuscular septum
. Osborne's ligament
. Arcade of Frohse
. Lacertus fibrosus

Correct Answer & Explanation

. Struthers ligament

Explanation

Osborne's ligament (the cubital tunnel retinaculum) bridges the two heads of the flexor carpi ulnaris and forms the roof of the cubital tunnel. Release of this structure is a critical step in ulnar nerve decompression.

Question 4432

Topic: 7. Hand and Wrist

During upper extremity embryological development, a mutation resulting in the overexpression of the Sonic hedgehog (SHH) gene in the anterior margin of the limb bud will most likely result in which of the following congenital anomalies?

. Radial club hand
. Ulnar dimelia (Mirror hand)
. Phocomelia
. Syndactyly
. Transverse radial deficiency

Correct Answer & Explanation

. Radial club hand

Explanation

The Zone of Polarizing Activity (ZPA) is located at the posterior margin of the developing limb bud and secretes the Sonic hedgehog (SHH) protein. SHH dictates radioulnar (anterior-posterior) patterning. Ectopic expression or a graft of the ZPA to the anterior margin of the limb bud leads to duplication of posterior structures, resulting clinically in ulnar dimelia (mirror hand).

Question 4433

Topic: Wrist & Carpus

An orthopedic investigator conducts a randomized controlled trial comparing two surgical techniques for distal radius fractures. The study concludes there is no significant difference between the two treatments (p = 0.08), but a post-hoc power analysis reveals the study power was only 60%. Which of the following statements is mathematically true regarding this study design?

. There is an 8% chance of a Type I error.
. The study has a 40% probability of a Type II error.
. The study is adequately powered to detect a clinically meaningful difference.
. Increasing the sample size would predictably decrease the power of the study.
. A Type I error definitively occurred.

Correct Answer & Explanation

. There is an 8% chance of a Type I error.

Explanation

Statistical power is the probability of correctly rejecting the null hypothesis when it is false, defined as (1 - Beta). If the power is 60%, then Beta (the probability of a Type II error, or failing to reject a false null hypothesis) is 40%. Because the study is underpowered (standard convention requires >80% power), there is a high risk that a true difference exists but was not detected due to insufficient sample size.

Question 4434

Topic: Nerve & Tendon

A 6-year-old boy presents to the emergency department after a fall off monkey bars. Radiographs reveal a widely displaced, extension-type supracondylar humerus fracture. On examination, he is unable to actively flex the interphalangeal joint of his thumb and the distal interphalangeal joint of his index finger. Which nerve is injured?

. Radial nerve
. Ulnar nerve
. Anterior interosseous nerve (AIN)
. Posterior interosseous nerve (PIN)
. Main trunk of the median nerve

Correct Answer & Explanation

. Anterior interosseous nerve (AIN)

Explanation

The anterior interosseous nerve (AIN) is the most frequently injured nerve in extension-type supracondylar humerus fractures. Clinically, it presents as an inability to form the 'A-OK' sign due to weakness of the flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) to the index finger.

Question 4435

Topic: 7. Hand and Wrist

A 55-year-old female undergoes open reduction internal fixation of a distal radius fracture with a volar locking plate. Six months postoperatively, she suddenly loses the ability to actively flex the interphalangeal joint of her thumb. What is the most likely cause of this complication?

. Delayed anterior interosseous nerve palsy
. Extensor pollicis longus (EPL) tendon rupture
. Flexor pollicis longus (FPL) tendon rupture
. Late-onset median nerve compression
. Prominent dorsal screws irritating the extensor tendons

Correct Answer & Explanation

. Flexor pollicis longus (FPL) tendon rupture

Explanation

Flexor pollicis longus (FPL) tendon rupture is a known complication of volar plating for distal radius fractures, typically occurring when the plate is positioned too distally, projecting volar to the 'watershed line', causing mechanical attrition of the tendon.

Question 4436

Topic: 7. Hand and Wrist

Which of the following defects occurs in Albright hereditary osteodystrophy (pseudohypoparathyroidism):

. Type X collagen
. Sulfate transporter gene
. Beta glucosidase
. Galpha S (GNAS1)
. C arbonic anhydrase type II, proton pump

Correct Answer & Explanation

. Type X collagen

Explanation

Pseudohypoparathyroidism (PHP) (Albright Hereditary Osteodystrophy [AHO]) - end organ insensitivity; in AHO, germline mutation that leads to loss of function of Galpha S (GNAS1); causes end-organ resistance to PTH (Zaleske).1/. PHP - short stature, short metacarpals (4th and 5th), rounded facies a. Mental retardation, tetanyb. Sex-linked dominant2/. Laboratory features a. Hypocalcemiab. Hyperphopshatemia c. Normal PTH3/. Other featuresThe other responses refer to:Metaphyseal chondrodysplasia (Schmid type): Type X collagenDiastrophic dysplasia: Sulfate transporter geneGaucher's disease: Beta glucosidaseOsteopetrosis: C arbonic anhydrase type II, proton pump

Question 4437

Topic: 7. Hand and Wrist
The patient in Figure 55 is actively attempting to make a fist. This clinical scenario suggests which of the following anatomic lesions?
. Median nerve lesion in the arm
. Radial nerve lesion in the arm
. Anterior interosseous nerve syndrome
. Posterior interosseous nerve syndrome
. Median neuropathy at the wrist

Correct Answer & Explanation

. Anterior interosseous nerve syndrome

Explanation

The inability to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (the 'OK' sign) is characteristic of an anterior interosseous nerve syndrome.

Question 4438

Topic: 7. Hand and Wrist
A 24-year-old man has a deep knife wound across the dorsal aspect of his wrist, transecting all of his wrist and finger extensor tendons. How does the surgeon determine which of the proximal tendon stumps in the fourth dorsal compartment is the extensor indicis proprius?
. The tendon runs in a separate compartment.
. The tendon has a more circular cross section.
. The tendon has the most distal muscle belly.
. The tendon is the most radial and superficial.
. The tendon has two separate slips.

Correct Answer & Explanation

. The tendon has the most distal muscle belly.

Explanation

The extensor indicis proprius (EIP) muscle belly is located more distally than the extensor digitorum communis (EDC) muscle bellies, allowing for identification of the EIP tendon stump.

Question 4439

Topic: 7. Hand and Wrist

A 45-year-old female falls on an outstretched hand and presents with a displaced intra-articular fracture of the distal radius. The injury imaging demonstrates volar displacement of a marginal fracture fragment with the carpus following the fragment.

In this type of fracture (volar Barton's), which of the following structures remains attached to the displaced volar marginal fragment, directly mediating the volar subluxation of the carpus?

. Extensor carpi radialis brevis tendon
. Brachioradialis tendon
. Radioscaphocapitate ligament
. Pronator quadratus muscle
. Triangular fibrocartilage complex (TFCC)

Correct Answer & Explanation

. Extensor carpi radialis brevis tendon

Explanation

A volar Barton's fracture is a shear injury where the volar marginal articular fragment of the distal radius is displaced volarly. The strong volar radiocarpal ligaments, predominantly the radioscaphocapitate (RSC) and long radiolunate (LRL) ligaments, remain attached to this volar fragment. Because these ligaments tether the proximal carpal row to the distal radius, the carpus subluxates volarly along with the fracture fragment. Anatomic reduction and buttress plate fixation are required to restore joint congruity and stability.

Question 4440

Topic: 7. Hand and Wrist

A 22-year-old collegiate golfer presents with chronic, recalcitrant volar-ulnar wrist pain. A carpal tunnel radiograph view confirms a displaced fracture of the hook of the hamate. After 3 months of failed conservative management, surgical excision of the fractured fragment is planned. During the approach and excision, which nerve is anatomically at greatest risk of iatrogenic injury?

. Median nerve
. Superficial sensory branch of the radial nerve
. Deep motor branch of the ulnar nerve
. Recurrent motor branch of the median nerve
. Palmar cutaneous branch of the median nerve

Correct Answer & Explanation

. Median nerve

Explanation

The deep motor branch of the ulnar nerve travels in Guyon's canal and courses radially, tightly hooking around the base of the hook of the hamate to supply the intrinsic muscles of the hand (interossei, adductor pollicis, and the two ulnar lumbricals). Because of its intimate anatomic proximity to the hamate hook, it is at high risk of iatrogenic injury during surgical excision of the fragment.

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