Biology, Genetics & Bone Healing MCQs

According to Perren's strain theory of fracture healing, what is the optimal range of interfragmentary strain required to promote secondary bone healing via a cartilaginous callus?

A 45-year-old patient presents with diffuse bone pain, muscle weakness, and pseudofractures (Looser zones) on radiographs. Labs demonstrate hypocalcemia and hypophosphatemia. A bone biopsy would most likely show which of the following classic histological features?

A 72-year-old woman is prescribed teriparatide for severe osteoporosis. Which of the following best describes the cellular mechanism by which this medication exerts its primary anabolic effect?

A novel therapeutic agent for osteoporosis functions by inhibiting sclerostin. Which of the following pathways is directly affected by this inhibition?

During the process of secondary fracture healing, the initial soft callus is eventually replaced by hard callus. This process is most dependent on which of the following biological phenomena?

Demineralized bone matrix (DBM) is commonly used as a bone graft substitute. Which of the following bone graft properties is preserved in DBM?

Nitrogen-containing bisphosphonates, such as alendronate, inhibit osteoclast function and induce apoptosis. What is the specific intracellular target of these medications?

A 14-year-old boy presents with multiple fractures and a history of delayed tooth eruption. Radiographs show diffusely dense, 'bone-within-bone' appearance. His condition is caused by a genetic mutation affecting a specific enzyme required for proper bone resorption. Which of the following is the primary function of this enzyme in the osteoclast?

An investigational drug for the treatment of severe osteoporosis acts by inhibiting sclerostin. By neutralizing sclerostin, this medication primarily increases bone mass through which of the following mechanisms?

A newborn is evaluated for absent clavicles, open cranial sutures, and delayed fontanelle closure. This condition is associated with a mutation in a master transcription factor essential for osteoblast differentiation. Which of the following genes is most likely mutated?

Bone morphogenetic proteins (BMPs) are commonly used in spinal fusion surgery to promote osteoinduction. Following the binding of BMP to its cell surface receptor, which intracellular signaling molecules are directly phosphorylated to translocate to the nucleus and regulate gene transcription?

During the incorporation of a structural cortical bone allograft, the process involves concurrent osteoclastic resorption of the graft and osteoblastic bone formation. Which of the following best describes this biologic process?

Articular cartilage exhibits unique biomechanical properties to resist both compressive and tensile forces. Which component of the extracellular matrix is primarily responsible for the compressive stiffness of articular cartilage?

A 4-year-old boy presents with diffuse bone pain, gingival bleeding, and metaphyseal radiolucent bands on radiographs. The underlying nutritional deficiency impairs the function of an enzyme essential for collagen synthesis. Which step in collagen synthesis is primarily affected?

Intermittent administration of parathyroid hormone (PTH) analogues, such as teriparatide, is used to treat severe osteoporosis. What is the primary cellular mechanism by which intermittent PTH therapy increases bone mineral density?

According to Perren's strain theory, what level of tissue strain optimally promotes the formation of woven bone during secondary fracture healing?

Which of the following bone graft substitutes is considered exclusively osteoconductive and lacks both osteoinductive and osteogenic properties?

Rigid plate fixation of a transverse diaphyseal fracture leading to absolute stability primarily heals via which biological process?

Parathyroid hormone (PTH) stimulates bone resorption primarily by binding to receptors on which of the following cell types?