Biology, Genetics & Bone Healing MCQs

A 68-year-old woman is prescribed alendronate for the treatment of severe osteoporosis. Nitrogen-containing bisphosphonates inhibit bone resorption primarily by blocking which of the following enzymes in the osteoclast?

During the incorporation of a massive structural cortical bone allograft, the process of creeping substitution is initiated. Which of the following biological events must occur first to allow creeping substitution to proceed?

Sclerostin is a key regulatory protein in bone metabolism and is the target of the monoclonal antibody romosozumab. Sclerostin exerts its primary osteo-regulatory effect by inhibiting which of the following intracellular signaling pathways?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized to enhance bone healing in specific fusion environments. BMPs transmit their osteoinductive intracellular signals primarily through which of the following secondary messengers?

According to Perren's strain theory of fracture healing, the mechanical environment dictates the type of tissue that forms in a fracture gap. Which type of tissue will predominantly form if the interfragmentary strain is between 2% and 10%?

A 55-year-old patient with end-stage chronic kidney disease presents with hypocalcemia, osteomalacia, and secondary hyperparathyroidism. This metabolic bone disease is primarily driven by a deficiency in which of the following steps of vitamin D metabolism?

During the reparative phase of secondary fracture healing, the soft fibrocartilaginous callus is gradually replaced by a hard, bony callus. This specific tissue transition occurs primarily via which of the following biological mechanisms?

Osteoprotegerin (OPG) plays a critical role in maintaining bone mass and preventing excessive resorption. What is the primary molecular function of OPG within the bone remodeling microenvironment?

A 72-year-old woman with severe osteoporosis and a recent vertebral compression fracture is being evaluated for teriparatide therapy. Which of the following elements of her medical history represents an absolute contraindication to the use of this medication?

A 65-year-old woman is prescribed denosumab for osteoporosis. This medication works by inhibiting bone resorption through a mechanism that most closely mimics which of the following endogenous molecules?

A 55-year-old patient receives a recombinant human Bone Morphogenetic Protein (rhBMP-2) graft during a spinal fusion. Which intracellular signaling molecules are directly phosphorylated after BMP-2 binds to its cell surface receptors?

A 70-year-old woman is treated with intermittent low-dose teriparatide. The anabolic effect of this drug on bone is primarily mediated by the stimulation of which of the following?

A surgeon decides to treat a nonunion with distraction osteogenesis. The process of bone formation during distraction osteogenesis occurs primarily through which mechanism?

Romosozumab is a bone-building medication recently approved for severe osteoporosis. It exerts its dual effect of increasing bone formation and decreasing bone resorption by binding to and inhibiting:

Vitamin D plays a critical role in calcium homeostasis and bone health. The final step in the formation of the most active form of Vitamin D (1,25-dihydroxyvitamin D3) occurs in the kidney and is catalyzed by which enzyme?

A fracture is rigidly fixed with a compression plate, achieving absolute stability and a gap of less than 0.01 mm. Under these conditions, the fracture will heal via primary bone healing, which is microscopically characterized by:

A 65-year-old woman is treated with a monoclonal antibody for osteoporosis that mimics the physiological role of osteoprotegerin (OPG). What is the primary mechanism of action of this medication?

Demineralized bone matrix (DBM) is used during a spinal fusion. Which of the following components is primarily responsible for the osteoinductive properties of this graft material?

During the inflammatory phase of fracture healing, which of the following cell types is primarily responsible for the initial clearing of necrotic tissue and secretion of cytokines to recruit mesenchymal stem cells?