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1. General Principles & Basic Science MCQs

Practice Set 59 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1161

Topic: 1. General Principles & Basic Science

Phonopheresis is:

. Delivery of heat to the tissues with a special oval-shaped attachment
. Aspiration of blood with concentration of platelets for re-injection
. Delivery of medicine through the skin using ultrasound
. Using ultrasound in a rapid, deep massage-type application
. Delivery of substimulus auditory waves to the tissue

Correct Answer & Explanation

. Delivery of medicine through the skin using ultrasound

Explanation

Phonopheresis is delivery of medicine through the skin using ultrasound. Although there is some question as to whether the medications are more effectively absorbed or delivered with ultrasound use, this is a described modality.

Question 1162

Topic: 1. General Principles & Basic Science

Iontophoresis delivers medications such as analgesics or steroids through the skin using an electrical charge.

. True
. False Iontophoresis uses a direct or galvanic current to drive medications transdermally and is used for scar management and pain control.

Correct Answer & Explanation

. True

Explanation

Question 1163

Topic: 1. General Principles & Basic Science

Types of nerve tissues surrounding the axons include all of the following EXC EPT:

. Endoneurium
. Hyponeurium
. Perineurium
. Mesoneurium
. Epineurium

Correct Answer & Explanation

. Mesoneurium

Explanation

The structures surrounding the axons and Schwann cells include the endoneurium, perineurium, and epineurium. The mesoneurium is an adventitial layer in addition.

Question 1164

Topic: 1. General Principles & Basic Science

The Seddon grades of nerve injury include all of the following EXC EPT:

. Neuropraxia
. Axonotmesis
. Neurotmesis
. Schwann cell disruption

Correct Answer & Explanation

. Neuropraxia

Explanation

Neuropraxic injuries are stretch injuries to the nerve. Axonotmetic injury involves a more severe injury with loss of continuity of axons, and connective tissue elements remain intact. Neurotmesis is a complete nerve discontinuity. Schwann cell disruption occurs in neurotmesis but is not among the grades of Seddon nerve injury.

Question 1165

Topic: 1. General Principles & Basic Science

Younger age is associated with worse outcomes with nerve repair.

. True
. False Younger age is associated with improved functional outcome after nerve repair, particularly regarding sensory recovery.

Correct Answer & Explanation

. True

Explanation

Question 1166

Topic: 1. General Principles & Basic Science

Optimum conditions for nerve healing after direct repair include:

. Gapping at suture repair site
. Tension-free repair
. Early motion of extremity
. Preservation of all tissue whether devitalized or viable
. lacing sutures through the endoneurium to increase repair strength

Correct Answer & Explanation

. Tension-free repair

Explanation

Tension-free repair is the optimal technique to improve the potential for nerve recovery. Gapping, failure to splint to prevent tension on the nerve with motion, and failure to excise scarred or devitalized nerve tissue are impairments to successful nerve repairs. Suture repairs through the deep nerve segments can damage the axons. Sutures should be placed through the epineurium or, in a grouped fascicular repair, through the perineurium around the fascicles.

Question 1167

Topic: 1. General Principles & Basic Science

Gunshot or missile wounds can frequently cause neuropraxic injuries to peripheral nerves.

. True
. False Missile wounds can cause a blast stretch injury to peripheral nerves and may recover with observation.

Correct Answer & Explanation

. True

Explanation

Question 1168

Topic: 1. General Principles & Basic Science

In healthy articular cartilage, which structural component is primarily responsible for providing compressive stiffness and drawing water into the extracellular matrix?

. Type II collagen
. Aggrecan
. Hyaluronic acid
. Type I collagen
. Fibronectin

Correct Answer & Explanation

. Aggrecan

Explanation

Aggrecan, a major proteoglycan in cartilage, is highly negatively charged due to its glycosaminoglycan chains. This draws water into the matrix via Donnan osmotic pressure, providing the tissue with its characteristic compressive stiffness.

Question 1169

Topic: Biology, Genetics & Bone Healing

According to Perren's strain theory, absolute stability and primary bone healing require the interfragmentary strain at the fracture gap to be maintained below what critical threshold?

. 2%
. 10%
. 15%
. 20%
. 25%

Correct Answer & Explanation

. 2%

Explanation

Primary bone healing requires absolute stability with interfragmentary strain maintained below 2%. This low-strain environment allows for direct osteonal remodeling (cutting cones) without intermediate callus formation.

Question 1170

Topic: 1. General Principles & Basic Science

In obstetric brachial plexus injury, an indicator of plexus recovery at 3 months is the return of the:

. Biceps muscle
. Triceps muscle
. Brachioradialis muscle
. Latissimus muscle
. Teres major muscle

Correct Answer & Explanation

. Biceps muscle

Explanation

Biceps recovery at 3 months is the single most important indicator of recovery in obstetric plexus palsy.

Question 1171

Topic: 1. General Principles & Basic Science
At what degree of flexion is ulnar collateral ligament injury tested:
. 0° of metacarpophalangeal (MCP) joint flexion
. 30° of MCP joint flexion
. 60° of MCP joint flexion
. 90° of MCP joint flexion
. 120° of MCP joint flexion

Correct Answer & Explanation

. 30° of MCP joint flexion

Explanation

At 30° of MCP joint flexion, the ulnar collateral ligament is isolated from the volar plate.

Question 1172

Topic: 1. General Principles & Basic Science
Which of the following structures are found within the first dorsal compartment:
. Abductor pollicis longus and extensor indicis
. Abductor pollicis longus and extensor pollicis longus
. Abductor pollicis longus and extensor pollicis brevis
. Abductor pollicis brevis and extensor pollicis longus
. Extensor carpi radialis longus and extensor pollicis brevis

Correct Answer & Explanation

. Abductor pollicis longus and extensor pollicis brevis

Explanation

The first dorsal compartment encompasses the abductor pollicis longus and extensor pollicis brevis. Multiple slips of abductor pollicis brevis may be present, which is important in de Quervain's release.

Question 1173

Topic: Surgical Anatomy & Approaches

All of the following transfers may be used to improve function in a patient who has had radial nerve paralysis longer than 6 months, except:

. Pronator to extensor carpi radialis brevis
. Flexor carpi radialis extensors
. Flexor digitorum superficialis of the ring finger to digital extensors
. Flexor digitorum superficialis of the ring finger to brachioradialis
. Flexor palmaris longus to extensor pollicis longus

Correct Answer & Explanation

. Pronator to extensor carpi radialis brevis

Explanation

Radial nerve paralysis is a common injury, and many patients recover after repair. Tendon transfers should be delayed until sufficient time for reinnervation has passed. Pronator to extensor carpi radialis brevis can be performed at time of nerve repair to provide wrist extension and grasp during period of nerve recovery. Transfers for radial nerve palsy need to address wrist extension, thumb extension, and finger extenstion. All of the above transfer would provide these functions except a transfer to the brachioradialis.

Question 1174

Topic: Biology, Genetics & Bone Healing

Bone morphogenetic proteins (BMPs) are used to enhance bone healing. Which of the following BMPs is an FDA-approved osteoinductive agent commonly used in anterior lumbar interbody fusion?

. BMP-1
. BMP-2
. BMP-3
. BMP-4
. BMP-12

Correct Answer & Explanation

. BMP-2

Explanation

Recombinant human BMP-2 (rhBMP-2) is heavily utilized and FDA-approved for specific spinal fusions, including ALIF with a specific cage. BMP-2 and BMP-7 are the primary osteoinductive BMPs used clinically.

Question 1175

Topic: Biology, Genetics & Bone Healing

In the process of secondary bone healing, which physiological phase is characterized by the replacement of the cartilaginous soft callus with woven bone through endochondral ossification?

. Inflammatory phase
. Soft callus phase
. Hard callus phase
. Remodeling phase
. Hematoma phase

Correct Answer & Explanation

. Hard callus phase

Explanation

The hard callus phase of secondary fracture healing involves the mineralization of the fibrocartilaginous soft callus, converting it into woven bone. This is primarily achieved via endochondral ossification.

Question 1176

Topic: 1. General Principles & Basic Science

Articular cartilage derives its unique resilience and capacity to resist extreme compressive forces primarily from which of the following molecular interactions?

. The tensile strength of Type I collagen fibrils
. Negatively charged proteoglycans (Aggrecan) drawing and trapping water
. The rigid lattice structure of Type II collagen
. Elastin fibers within the superficial zone
. Fibronectin cross-linking in the deep zone

Correct Answer & Explanation

. Negatively charged proteoglycans (Aggrecan) drawing and trapping water

Explanation

The compressive stiffness of articular cartilage is governed by the osmotic swelling pressure of the negatively charged glycosaminoglycans on aggrecan molecules, which strongly attract and retain water within the Type II collagen meshwork.

Question 1177

Topic: Surgical Anatomy & Approaches

A 30-year-old man sustains a closed midshaft humeral fracture after a fall.

Upon initial clinical examination in the emergency department, he exhibits an inability to actively extend his wrist and metacarpophalangeal joints. Sensation is decreased over the dorsal first web space. What is the most appropriate initial management for this neurological deficit?

. Immediate surgical nerve exploration
. Immediate EMG and nerve conduction studies
. Observation and supportive splinting for 3 to 4 months
. Primary tendon transfers to restore extension
. Prophylactic fasciotomies of the forearm

Correct Answer & Explanation

. Observation and supportive splinting for 3 to 4 months

Explanation

The standard of care for a primary radial nerve palsy associated with a closed midshaft humeral fracture is observation and supportive dynamic splinting. The vast majority of these injuries are neuropraxias or axonotmeses that will spontaneously recover within 3 to 4 months.

Question 1178

Topic: Surgical Anatomy & Approaches

A 22-year-old patient with an upper trunk (C5-C6) brachial plexus injury is scheduled for an Oberlin transfer to restore elbow flexion, as his lower trunk function is fully intact. Which of the following best describes the standard surgical technique for an Oberlin transfer?

. Transfer of a redundant fascicle of the ulnar nerve to the biceps motor branch
. Transfer of the spinal accessory nerve to the suprascapular nerve
. Transfer of the medial pectoral nerve to the musculocutaneous nerve
. Transfer of intercostal nerves to the musculocutaneous nerve
. Transfer of a fascicle of the radial nerve to the axillary nerve

Correct Answer & Explanation

. Transfer of a redundant fascicle of the ulnar nerve to the biceps motor branch

Explanation

The classic Oberlin transfer is a nerve transfer procedure that restores elbow flexion by mobilizing a redundant motor fascicle from the uninjured ulnar nerve and coapting it directly to the motor branch of the biceps muscle.

Question 1179

Topic: 1. General Principles & Basic Science

Which digit is most commonly affected by macrodactyly:

. Thumb
. Index
. MIddle
. Ring
. Small

Correct Answer & Explanation

. Index

Explanation

The index finger is most frequently affected, although multiple digital enlargement is actually more commonly seen.

Question 1180

Topic: 1. General Principles & Basic Science

The most accepted theory for the cause of macrodactyly is:

. Idiopathic
. Neural
. Vascular
. Humoral
. C ongenital

Correct Answer & Explanation

. Neural

Explanation

Some surgeons believe that macrodactyly is a variant of neurofibromatosis. Although macrodactyly is not an inherited anomaly, there are syndromes that may be associated with enlarged digits such as Proteus syndrome. Although numerous causes have been suggested, the most accepted theory was described by Inglis in 1950. He theorized that the abnormal nerves exert influence on the local tissues to stimulate growth.

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