Menu

1. General Principles & Basic Science MCQs

Practice Set 651 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 13001

Topic: 1. General Principles & Basic Science

When evaluating the biomechanical properties of orthopedic screws, which of the following characteristics is most directly proportional to its pullout strength?

. Inner (root) diameter
. Thread pitch
. Outer (thread) diameter
. Core diameter
. Thread length

Correct Answer & Explanation

. Outer (thread) diameter

Explanation

The pullout strength of a screw is most heavily dependent on its outer (thread) diameter. Other factors include the length of thread engagement and the shear strength of the surrounding bone.

Question 13002

Topic: 1. General Principles & Basic Science
A 55-year-old poorly controlled diabetic patient presents with rapidly spreading extremity erythema, severe pain out of proportion to exam findings, and palpable crepitus. The calculated LRINEC score is 10. What is the most critical initial step in management?
. Broad-spectrum intravenous antibiotics alone
. MRI of the extremity with intravenous contrast
. Hyperbaric oxygen therapy
. Immediate surgical exploration and debridement
. Diagnostic bedside needle aspiration

Correct Answer & Explanation

. Immediate surgical exploration and debridement

Explanation

The patient has clinical signs of necrotizing fasciitis, supported by a high Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score. Immediate aggressive surgical debridement is the definitive and life-saving treatment.

Question 13003

Topic: Biomechanics & Biomaterials
In total joint arthroplasty, the process of highly cross-linking ultra-high molecular weight polyethylene (UHMWPE) achieves which of the following mechanical changes?
. Decreased wear resistance
. Increased fatigue strength
. Decreased wear rate but decreased fatigue strength
. Increased ductility and toughness
. Increased yield strength

Correct Answer & Explanation

. Decreased wear rate but decreased fatigue strength

Explanation

Highly cross-linking UHMWPE significantly improves its wear resistance, thereby decreasing the wear rate. However, this process alters the mechanical properties by decreasing its fatigue strength, yield strength, and toughness.

Question 13004

Topic: Biology, Genetics & Bone Healing

Which type of fracture healing is characterized by intermediate callus formation and typically occurs under conditions of relative mechanical stability?

. Primary bone healing
. Intramembranous ossification only
. Secondary bone healing
. Cutting cone remodeling
. Haversian remodeling

Correct Answer & Explanation

. Secondary bone healing

Explanation

Secondary bone healing involves an inflammatory phase, soft callus formation, hard callus formation, and remodeling. It occurs in fractures treated with relative stability, such as intramedullary nailing or external fixation.

Question 13005

Topic: 1. General Principles & Basic Science
Which of the following is the predominant collagen type found in the extracellular matrix of normal human articular hyaline cartilage?
. Type I
. Type II
. Type III
. Type IV
. Type X

Correct Answer & Explanation

. Type II

Explanation

Type II collagen constitutes approximately 90-95% of the collagen in normal articular hyaline cartilage. It provides the tensile strength and structural framework of the cartilage matrix.

Question 13006

Topic: Infection, Pharmacology & VTE

By which of the following mechanisms do biofilms primarily protect bacteria on orthopedic implants from systemic antibiotics?

. Rapid bacterial cellular replication
. Enzymatic degradation of circulating antibiotics
. Physical barrier via an extracellular polymeric substance matrix
. Alteration of bacterial target site receptors
. Increased density of intracellular drug efflux pumps

Correct Answer & Explanation

. Physical barrier via an extracellular polymeric substance matrix

Explanation

Biofilms protect sessile bacteria primarily by embedding them in a thick extracellular polymeric substance (EPS) matrix. This matrix acts as a physical barrier, limiting the penetration of antibiotics and immune cells.

Question 13007

Topic: 1. General Principles & Basic Science

According to Seddon's classification of nerve injuries, an axonotmesis injury is best defined by which of the following pathological descriptions?

. Disruption of the myelin sheath only
. Disruption of the axon and myelin sheath with preservation of connective tissue stroma
. Disruption of the axon and endoneurium with intact perineurium
. Complete transection of the nerve including the epineurium
. Focal conduction block without Wallerian degeneration

Correct Answer & Explanation

. Disruption of the axon and myelin sheath with preservation of connective tissue stroma

Explanation

Axonotmesis refers to a nerve injury where the axon and myelin sheath are disrupted, leading to Wallerian degeneration distally, but the supporting connective tissue frameworks (endoneurium, perineurium, epineurium) remain intact. Recovery is possible because the intact stroma guides regenerating axons.

Question 13008

Topic: 1. General Principles & Basic Science
Low molecular weight heparin (LMWH) provides deep vein thrombosis prophylaxis primarily by exerting a potent inhibitory effect on which of the following components of the coagulation cascade?
. Factor IIa (Thrombin)
. Factor Xa
. Factor VIIa
. Factor VIII
. Vitamin K epoxide reductase

Correct Answer & Explanation

. Factor Xa

Explanation

LMWH works by binding to antithrombin III, which then potently and selectively inactivates Factor Xa. It has a much lower affinity for inhibiting Thrombin (Factor IIa) compared to unfractionated heparin.

Question 13009

Topic: 1. General Principles & Basic Science

When evaluating orthopedic pathology on T1-weighted Magnetic Resonance Imaging (MRI) sequences, which of the following normal tissues typically demonstrates the highest signal intensity (brightest appearance)?

. Cortical bone
. Ligaments
. Cerebrospinal fluid
. Subcutaneous fat
. Skeletal muscle

Correct Answer & Explanation

. Subcutaneous fat

Explanation

On T1-weighted MRI sequences, fat appears very bright (high signal intensity). Water and fluid appear dark on T1, while cortical bone and ligaments appear consistently dark on all standard MRI sequences.

Question 13010

Topic: Physiology & Rehabilitation

During rehabilitation, patients perform various types of muscle contractions. Which type of contraction generates the highest maximum force and is most commonly associated with delayed onset muscle soreness (DOMS)?

. Isotonic concentric
. Isometric
. Isokinetic
. Eccentric
. Tetanic

Correct Answer & Explanation

. Eccentric

Explanation

Eccentric contractions occur when a muscle lengthens while under tension. They can generate the highest forces of any contraction type but are also most highly correlated with microtrauma and subsequent delayed onset muscle soreness.

Question 13011

Topic: Biology, Genetics & Bone Healing

According to Perren's strain theory regarding fracture healing, what is the expected tissue formation response when the interfragmentary strain at a fracture site exceeds 10%?

. Lamellar bone forms immediately
. Woven bone forms
. Cartilage forms to bridge the gap
. Granulation tissue forms but bone and cartilage cannot form
. Primary bone healing via cutting cones occurs

Correct Answer & Explanation

. Granulation tissue forms but bone and cartilage cannot form

Explanation

Perren's strain theory dictates that tissues cannot form if the strain exceeds their tolerance. Bone tolerates less than 2% strain, cartilage tolerates up to 10%, and strains greater than 10% will only allow the formation of granulation tissue, leading to nonunion.

Question 13012

Topic: Surgical Anatomy & Approaches

A 35-year-old man with a chronic high radial nerve palsy undergoes functional tendon transfers. The surgeon transfers the pronator teres (PT) to the extensor carpi radialis brevis (ECRB) to restore wrist extension, and the flexor carpi ulnaris (FCU) to the extensor digitorum communis (EDC) to restore finger extension. Which of the following is the most appropriate transfer to restore thumb extension in this patient?

. Flexor carpi radialis to extensor digitorum communis
. Palmaris longus to extensor pollicis longus
. Pronator teres to extensor carpi radialis longus
. Flexor digitorum superficialis to extensor pollicis brevis
. Extensor indicis proprius to extensor pollicis longus

Correct Answer & Explanation

. Palmaris longus to extensor pollicis longus

Explanation

In a high radial nerve palsy, the palmaris longus (PL) to extensor pollicis longus (EPL) transfer is the gold standard for restoring thumb extension. The extensor indicis proprius (EIP) to EPL transfer is commonly used for spontaneous EPL ruptures, but it cannot be used in a radial nerve palsy because the EIP is innervated by the posterior interosseous nerve (PIN), which is nonfunctional in this scenario.

Question 13013

Topic: 1. General Principles & Basic Science

A 45-year-old woman presents with severe, excruciating pain at the tip of her left index finger. The pain is exacerbated by cold weather. On examination, point tenderness is elicited with a pinhead, and the pain resolves temporarily when a tourniquet is inflated around the base of the finger. Histological examination of the excised lesion would most likely reveal:

. Multinucleated giant cells and hemosiderin-laden macrophages
. Lobules of hypocellular hyaline cartilage
. Sheets of uniform, round cells surrounding branching vascular channels
. A cystic structure with a mucin-filled cavity and fibrous lining
. Proliferation of mature adipocytes with fine fibrous septa

Correct Answer & Explanation

. Sheets of uniform, round cells surrounding branching vascular channels

Explanation

The clinical presentation is classic for a glomus tumor, characterized by the triad of paroxysmal pain, point tenderness (Love's pin test), and cold sensitivity. Pain relief with ischemia is known as Hildreth's sign. Histologically, glomus tumors present as sheets of uniform, round-to-oval cells (glomus cells) surrounding fine vascular channels.

Question 13014

Topic: 1. General Principles & Basic Science

A 32-year-old professional boxer presents with pain over the long finger MCP joint after a punch. He cannot actively extend the MCP joint from a flexed position but can maintain extension if passively placed in that position. On examination, the extensor tendon subluxates ulnarly during active flexion. Assuming this is an acute injury (2 days old), what is the most appropriate initial management?

. Primary surgical repair of the radial sagittal band
. Splinting the MCP joint in full extension for 4-6 weeks with PIP free
. Splinting the PIP joint in extension for 6 weeks
. Primary surgical repair of the ulnar sagittal band
. Extensor indicis proprius transfer

Correct Answer & Explanation

. Splinting the MCP joint in full extension for 4-6 weeks with PIP free

Explanation

Acute sagittal band ruptures (within 3 weeks) are effectively treated non-operatively with an extension splint for the MCP joint for 4-6 weeks, leaving the PIP joint free. The radial sagittal band is most commonly injured, leading to ulnar subluxation of the extensor tendon. Surgical repair is indicated for chronic injuries or failed conservative management.

Question 13015

Topic: 1. General Principles & Basic Science
A 55-year-old woman with base of thumb pain has radiographs showing thumb CMC joint space narrowing, subchondral sclerosis, and a 3 mm radial osteophyte. The scaphotrapezial (STT) joint appears completely normal. According to the Eaton-Littler classification, what is the stage of her disease?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage III

Explanation

The Eaton-Littler classification stages thumb CMC arthritis: Stage I has normal joint space with possible capsular widening. Stage II has mild narrowing and osteophytes < 2 mm. Stage III is characterized by advanced CMC joint degeneration (sclerosis, joint space narrowing) and osteophytes > 2 mm, while the STT joint remains normal. Stage IV involves pantrapezial arthritis (including the STT joint).

Question 13016

Topic: 1. General Principles & Basic Science

In the context of digital amputations, which of the following scenarios represents a generally accepted absolute contraindication to attempted microvascular replantation?

. Amputation of a single digit in Zone II in a 25-year-old
. Amputation of the thumb at the MCP joint in a 60-year-old
. Avulsion injury of the ring finger in a 30-year-old mechanic
. Multiple level (segmental) amputations in the same digit
. Warm ischemia time of 4 hours for an amputated thumb

Correct Answer & Explanation

. Multiple level (segmental) amputations in the same digit

Explanation

Multiple level (segmental) amputations in the same digit is considered an absolute contraindication to replantation because of the inability to restore adequate vascularity and the guarantee of extremely poor functional outcomes. Single digit amputation in Zone II is a relative contraindication (except in children). Thumb replantation is almost always indicated regardless of age if feasible. Up to 12 hours of warm ischemia time is tolerated for digits.

Question 13017

Topic: Infection, Pharmacology & VTE

A 25-year-old man presents with an infected laceration over the 3rd metacarpophalangeal joint after striking another person in the mouth during an altercation. Wound cultures grow a fastidious Gram-negative rod. Which of the following is the most appropriate empiric antibiotic treatment for this specific pathogen?

. Cephalexin
. Clindamycin
. Amoxicillin-clavulanate
. Vancomycin
. Erythromycin

Correct Answer & Explanation

. Amoxicillin-clavulanate

Explanation

The scenario describes a classic "clenched fist injury" or human bite. The fastidious Gram-negative rod associated with human bites is Eikenella corrodens. The drug of choice for Eikenella and general human bite prophylaxis/treatment is amoxicillin-clavulanate. Cephalexin and clindamycin have poor coverage against Eikenella.

Question 13018

Topic: 1. General Principles & Basic Science

A 45-year-old man presents with a "snapping" sensation over the long finger metacarpophalangeal (MCP) joint. Examination demonstrates that when he makes a fist, the extensor tendon subluxates into the ulnar gutter. The tendon reduces when he actively extends his fingers. Which structure is most likely injured?

. Radial sagittal band
. Ulnar sagittal band
. Central slip
. Transverse retinacular ligament
. Oblique retinacular ligament

Correct Answer & Explanation

. Radial sagittal band

Explanation

The sagittal bands centralize the extensor tendon over the MCP joint. The radial sagittal band is injured most commonly (often termed "boxer's knuckle"), allowing the extensor tendon to subluxate or dislocate into the ulnar gutter during flexion. Ulnar sagittal band injuries are rare.

Question 13019

Topic: 1. General Principles & Basic Science
What is the standard, most widely recommended sequence of structural repair during the microsurgical replantation of a completely amputated digit?
. Bone fixation, extensor tendon, flexor tendon, arteries, nerves, veins
. Arteries, veins, bone fixation, flexor tendon, extensor tendon, nerves
. Bone fixation, arteries, veins, flexor tendon, extensor tendon, nerves
. Veins, arteries, bone fixation, extensor tendon, flexor tendon, nerves
. Extensor tendon, flexor tendon, bone fixation, arteries, nerves, veins

Correct Answer & Explanation

. Bone fixation, extensor tendon, flexor tendon, arteries, nerves, veins

Explanation

The classic and widely taught sequence for digital replantation is: 1) Bone fixation (establishes skeletal stability), 2) Extensor tendon repair, 3) Flexor tendon repair, 4) Arterial anastomosis, 5) Nerve repair, 6) Venous anastomosis, and 7) Skin closure. This is often remembered by the mnemonic BEFANV.

Question 13020

Topic: Biology, Genetics & Bone Healing

A 65-year-old female is started on denosumab for the treatment of osteoporosis. Which of the following best describes the molecular mechanism of this medication in altering bone biology?

. Directly inhibits carbonic anhydrase II within the ruffled border
. Binds to RANKL to prevent its interaction with the RANK receptor
. Acts as a bisphosphonate analog that induces osteoclast apoptosis
. Binds directly to the RANK receptor on osteoclasts acting as a competitive antagonist
. Promotes Osteoprotegerin (OPG) production from osteoblasts

Correct Answer & Explanation

. Binds to RANKL to prevent its interaction with the RANK receptor

Explanation

Denosumab is a fully human monoclonal antibody (IgG2) that specifically binds to the receptor activator of nuclear factor kappa-B ligand (RANKL). By binding to RANKL, it prevents RANKL from interacting with the RANK receptor on the surface of osteoclasts and their precursors. This effectively inhibits osteoclast survival, formation, and function, leading to decreased bone resorption.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page