Practice Set 294 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.
Romosozumab is an anabolic agent used for the treatment of severe osteoporosis. It exerts its effect primarily by neutralizing which of the following molecules?
. Sclerostin
To reduce stress shielding around a femoral stem, an implant designer wishes to use a material whose modulus of elasticity most closely approximates that of cortical bone. Which of the following materials has a Young's modulus closest to cortical bone?
. Titanium alloy
A patient taking daily high-dose celecoxib sustains a tibial shaft fracture. How might this medication impair fracture healing?
. Decreasing production of prostaglandins essential for endochondral ossification
According to Perren's strain theory, what is the maximum interfragmentary strain that will permit primary (direct) bone healing to occur without callus formation?
. Less than 2%
. Direct Factor Xa inhibitor
When designing a cortical bone screw, which of the following dimensional changes will most significantly increase its pullout strength?
. Increasing the outer thread diameter
A patient receives daily subcutaneous injections of teriparatide for severe osteoporosis. This treatment primarily relies on which of the following physiological principles?
. Intermittent low doses of PTH stimulate osteoblastic bone formation
Highly cross-linked polyethylene (HXLPE) is used in total hip arthroplasty to reduce wear rates. What biomechanical trade-off is most commonly associated with increasing the cross-linking of polyethylene?
. Decreased ultimate tensile strength and fatigue resistance
. Synthetic competitive inhibition of the lysine-binding sites on plasminogen
A typical stress-strain curve for cortical bone is being analyzed.
What term is used to describe the area under the entire stress-strain curve before the point of complete failure?
. Toughness
A patient exhibits perioral numbness, tinnitus, and arrhythmias immediately following a large-volume local anesthetic block with bupivacaine. Toxicity from this class of medication is primarily due to:
. Blockade of voltage-gated sodium channels in the central nervous and cardiovascular systems
When evaluating the ultrastructure of articular cartilage, which zone is characterized by the highest concentration of proteoglycans, the lowest water content, and collagen fibers oriented perpendicular to the joint surface?
. Deep (radial) zone
Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized as a bone graft substitute. Intracellular signaling of BMPs is primarily mediated by which of the following pathways?
. Smad 1/5/8 pathway
Which of the following best describes the molecular mechanism of action of nitrogen-containing bisphosphonates such as alendronate?
. Inhibition of farnesyl pyrophosphate synthase
In a stress-strain curve of a cortical bone specimen under tension, the area under the entire curve represents which of the following mechanical properties?
. Toughness
Which of the following best describes the process of "creeping substitution" observed during the incorporation of cortical bone grafts?
. Simultaneous osteoclastic resorption and osteoblastic formation along Haversian canals
A patient develops a methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. Vancomycin is initiated. What is the specific mechanism of action of this antibiotic?
. Binds to D-alanyl-D-alanine termini of peptidoglycan precursors
The pull-out strength of a cortical screw is most heavily dependent on which of the following design parameters?
. Outer (thread) diameter
Continuous high-dose administration of parathyroid hormone (PTH) results in which of the following primary cellular effects in bone?
. Upregulation of RANKL expression by osteoblasts
. Potentiation of antithrombin III with a higher affinity for Factor Xa than thrombin