Menu

1. General Principles & Basic Science MCQs

Practice Set 603 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 12041

Topic: Biomechanics & Biomaterials

In a standard stress-strain curve for an orthopedic biomaterial, the total area under the curve prior to the point of failure represents the material's:

. Stiffness
. Toughness
. Ductility
. Yield strength
. Viscoelasticity

Correct Answer & Explanation

. Stiffness

Explanation

Toughness is defined as the amount of energy a material can absorb before it fractures, represented by the total area under the stress-strain curve. Stiffness is represented by the slope of the linear elastic region.

Question 12042

Topic: 1. General Principles & Basic Science

Following a peripheral nerve transection and subsequent microsurgical repair, at what approximate rate do regenerating axons typically grow?

. 0.1 mm/day
. 1.0 mm/day
. 3.0 mm/day
. 5.0 mm/day
. 10.0 mm/day

Correct Answer & Explanation

. 0.1 mm/day

Explanation

After initial Wallerian degeneration and a latent period, peripheral nerve axons regenerate at an average rate of 1 mm per day. This equates to approximately one inch per month.

Question 12043

Topic: 1. General Principles & Basic Science
Which of the following correctly pairs the phase of ligament healing with its predominant cellular or extracellular matrix feature?
. Inflammatory phase - Type I collagen production
. Proliferative phase - Macrophage infiltration
. Remodeling phase - Conversion of Type III to Type I collagen
. Remodeling phase - Peak fibroblast proliferation
. Inflammatory phase - Type III collagen cross-linking

Correct Answer & Explanation

. Remodeling phase - Conversion of Type III to Type I collagen

Explanation

The remodeling phase of ligament healing is characterized by the gradual replacement of immature Type III collagen with stronger, more organized Type I collagen. The proliferative phase involves peak fibroblast activity and initial Type III collagen synthesis.

Question 12044

Topic: Biomechanics & Biomaterials
Highly cross-linked ultra-high-molecular-weight polyethylene (UHMWPE) is manufactured primarily to reduce which of the following?
. Adhesive wear
. Abrasive wear
. Fatigue failure
. Oxidation degradation
. Fretting wear

Correct Answer & Explanation

. Adhesive wear

Explanation

Highly cross-linked UHMWPE significantly reduces adhesive and abrasive wear in total joint arthroplasty. However, the cross-linking process can reduce the material's overall fatigue strength and fracture toughness.

Question 12045

Topic: Biology, Genetics & Bone Healing

According to Perren's strain theory, what is the maximum gap strain that allows for the formation of lamellar bone during fracture healing?

. 1-2%
. 5-10%
. 15-20%
. 30-40%
. >50%

Correct Answer & Explanation

. 1-2%

Explanation

Perren's strain theory states that lamellar bone can only form in stable environments with less than 2% strain. Granulation tissue tolerates 100% strain, while cartilage can tolerate up to 10% strain before tearing.

Question 12046

Topic: Biomechanics & Biomaterials

Which of the following orthopedic implant materials has a modulus of elasticity most similar to that of cortical bone, thereby minimizing stress shielding?

. Stainless steel
. Cobalt-chromium alloy
. Titanium alloy
. Alumina ceramic
. Polymethylmethacrylate (PMMA)

Correct Answer & Explanation

. Stainless steel

Explanation

Titanium alloys have a lower modulus of elasticity compared to stainless steel and cobalt-chromium, making them closer to the modulus of cortical bone. This reduces the risk of stress shielding and subsequent periprosthetic bone loss.

Question 12047

Topic: 1. General Principles & Basic Science

The primary glycosaminoglycans (GAGs) attached to the protein core of aggrecan in articular cartilage are:

. Hyaluronic acid and dermatan sulfate
. Chondroitin sulfate and keratan sulfate
. Heparan sulfate and chondroitin sulfate
. Keratan sulfate and hyaluronic acid
. Dermatan sulfate and heparan sulfate

Correct Answer & Explanation

. Hyaluronic acid and dermatan sulfate

Explanation

Aggrecan consists of a core protein with covalently attached chondroitin sulfate and keratan sulfate side chains. These negatively charged GAGs attract water, giving cartilage its unique compressive stiffness.

Question 12048

Topic: Biology, Genetics & Bone Healing

A direct tendon insertion into bone consists of four distinct transitional zones. What is the correct order of these zones from tendon to bone?

. Tendon, fibrocartilage, mineralized fibrocartilage, bone
. Tendon, mineralized fibrocartilage, fibrocartilage, bone
. Tendon, hyaline cartilage, mineralized hyaline cartilage, bone
. Tendon, disorganized collagen, organized collagen, bone
. Tendon, woven bone, lamellar bone, cortical bone

Correct Answer & Explanation

. Tendon, fibrocartilage, mineralized fibrocartilage, bone

Explanation

Direct tendon insertions (entheses) transition through four distinct zones: tendon, unmineralized fibrocartilage, mineralized fibrocartilage, and bone. This gradual structural transition helps dissipate mechanical stress at the insertion site.

Question 12049

Topic: Biology, Genetics & Bone Healing

Intermittent administration of parathyroid hormone (PTH), such as with teriparatide, primarily stimulates bone formation by:

. Directly inhibiting osteoclast activity
. Upregulating sclerostin expression
. Promoting osteoblast survival and preventing apoptosis
. Decreasing intestinal calcium absorption
. Stimulating the release of calcitonin

Correct Answer & Explanation

. Directly inhibiting osteoclast activity

Explanation

While continuous PTH causes bone resorption, intermittent PTH administration promotes bone formation by stimulating osteoblast differentiation and preventing osteoblast apoptosis. It also downregulates sclerostin.

Question 12050

Topic: Biomechanics & Biomaterials

A surgeon places a stainless steel screw into a titanium plate to fix a fracture. This combination places the construct at highest risk for which type of corrosion?

. Fretting corrosion
. Crevice corrosion
. Galvanic corrosion
. Pitting corrosion
. Intergranular corrosion

Correct Answer & Explanation

. Fretting corrosion

Explanation

Galvanic corrosion occurs when two dissimilar metals are placed in physical contact within an electrolytic medium, such as human body fluid. The less noble metal (anode) undergoes accelerated corrosion.

Question 12051

Topic: Physiology & Rehabilitation

Which type of muscle contraction generates the highest maximum force and is most commonly implicated in indirect muscle strain injuries?

. Concentric
. Isometric
. Eccentric
. Isokinetic
. Isotonic

Correct Answer & Explanation

. Concentric

Explanation

Eccentric contractions involve muscle lengthening under tension and generate the highest forces. They are the most common mechanism for indirect muscle strains due to the high stress placed on the myotendinous junction.

Question 12052

Topic: Biology, Genetics & Bone Healing

Bone Morphogenetic Protein 2 (BMP-2) induces osteoblastic differentiation primarily through the intracellular activation of which signaling pathway?

. Wnt/beta-catenin
. Notch signaling
. Smad 1/5/8
. JAK/STAT
. MAP kinase

Correct Answer & Explanation

. Wnt/beta-catenin

Explanation

BMPs bind to serine/threonine kinase receptors on the cell surface, which then phosphorylate intracellular Smad proteins (typically Smads 1, 5, and 8). These form a complex with Smad 4 and translocate to the nucleus to regulate target gene expression.

Question 12053

Topic: 1. General Principles & Basic Science

Under conditions of high load and low speed in a native synovial joint, which type of lubrication mechanism primarily protects the articular surfaces from direct contact?

. Hydrodynamic lubrication
. Elastohydrodynamic lubrication
. Boundary lubrication
. Weeping lubrication
. Squeeze-film lubrication

Correct Answer & Explanation

. Hydrodynamic lubrication

Explanation

Boundary lubrication is dependent on molecules like lubricin directly adhering to the articular surfaces, protecting them during high-load, low-speed situations. In these conditions, fluid films cannot be maintained.

Question 12054

Topic: 1. General Principles & Basic Science

Which of the following non-collagenous proteins is the most abundant in mature bone matrix and requires Vitamin K for its gamma-carboxylation to bind calcium effectively?

. Osteopontin
. Osteonectin
. Osteocalcin
. Bone sialoprotein
. Sclerostin

Correct Answer & Explanation

. Osteopontin

Explanation

Osteocalcin is the most abundant non-collagenous protein in bone. It is secreted by osteoblasts and requires Vitamin K-dependent gamma-carboxylation to effectively bind to the calcium in hydroxyapatite.

Question 12055

Topic: Biology, Genetics & Bone Healing

During secondary fracture healing, the predominant source of osteochondroprogenitor cells that form the external hard callus is the:

. Endosteum
. Bone marrow stroma
. Periosteum
. Circulating mesenchymal stem cells
. Skeletal muscle satellite cells

Correct Answer & Explanation

. Endosteum

Explanation

The cambium (inner) layer of the periosteum is highly cellular and provides the majority of osteochondroprogenitor cells required for external callus formation during secondary fracture healing.

Question 12056

Topic: 1. General Principles & Basic Science

Compared to calcium phosphate, calcium sulfate bone graft substitutes are characterized by which of the following properties?

. Slower resorption rate
. Higher ultimate compressive strength
. Osteoinductive potential
. Rapid resorption rate
. Higher mechanical structural support

Correct Answer & Explanation

. Slower resorption rate

Explanation

Calcium sulfate undergoes rapid resorption, often dissolving faster than new bone can form. Calcium phosphate has a much slower resorption profile and higher compressive strength, providing better long-term structural support.

Question 12057

Topic: Biology, Genetics & Bone Healing

Which of the following cells produce osteocalcin and bone sialoprotein:

. Osteocytes
. Osteoblasts
. Mast cells
. Osteoclasts
. Fibroblasts

Correct Answer & Explanation

. Osteocytes

Explanation

Osteoblasts are metabolically active cells that line the bone surface. Osteoblasts produce type I collagen and manynoncollagenous proteins such as osteocalcin, bone sialoprotein, and extracellular matrix proteins. Osteoblasts have large amounts of rough endoplasmiCreticulum because they prepare large amounts of protein for export out of the cell. The Golgi apparatus exports the protein.

Question 12058

Topic: Biology, Genetics & Bone Healing

Which of the following is the rate-limiting step in the production of biologically active Vitamin D:

. 25 hydroxylation in the liver
. Absorption of calcium in the duodenum
. Conversion of 7 dehydrocholesterol to vitamin D3 in the skin
. 1 hydroxylation in the kidney
. Absorption of calcium in the jejunum

Correct Answer & Explanation

. 25 hydroxylation in the liver

Explanation

The addition of a second hydroxyl group at the 1 position to 25 hydroxy vitamin D3 is the rate-limiting step in the formation of the active from of vitamin D3. Impaired renal function is common in older individuals

Question 12059

Topic: 1. General Principles & Basic Science

Figure 93

. Chromosome 17 mutation
. MYH3 mutation
. Embryonic vascular interruption
. Infantile vascular interruption
. Chromosome 11 mutation

Correct Answer & Explanation

. Chromosome 17 mutation

Explanation

- Sporadic inheritance

Question 12060

Topic: Infection, Pharmacology & VTE

What is the most common pathogen for soft-tissue infection of the foot caused by a puncture wound?

. Staphylococcus aureus
. Pseudomonas aeruginosa
. Eikenella corrodens
. Pasteurella multocida
. Vibrio species

Correct Answer & Explanation

. Staphylococcus aureus

Explanation

Staphylococcus and Streptococcus species are the most common causes of soft-tissue infections in the foot due to punctures. Pseudomonas is the most common cause of osteomyelitis of the foot due to puncture wounds. Pasteurella and Eikenella are seen in animal and human bites, respectively.Vibrio species are found in marine environments.

Test Yourself

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

On this Page