Biology, Genetics & Bone Healing MCQs

Absolute stability of a transverse radius fracture is achieved using a rigid compression plate, leading to primary bone healing. This specific healing process bypasses callus formation and relies entirely on which of the following cellular mechanisms?

The direct insertion of a ligament into bone is structurally designed to transition mechanical stress and prevent failure at the interface. Which of the following accurately represents the histological progression of this transition from ligament to bone?

Demineralized bone matrix (DBM) is commonly used as a bone graft extender. While lacking structural integrity, DBM is highly valued biologically because the demineralization process exposes specific growth factors, providing which primary property?

Romosozumab is a monoclonal antibody recently approved for the treatment of postmenopausal women with severe osteoporosis at high risk of fracture. What is the specific molecular target of this medication?

A healthy individual consumes a highly calcium-rich diet, triggering a transient elevation in serum calcium. In normal homeostasis, which hormone is secreted by the thyroid parafollicular cells to directly counteract this rise by inhibiting osteoclast activity?

Osteoprotegerin (OPG) regulates bone mass and prevents excessive bone resorption. It exerts this effect by acting as a decoy receptor for which of the following molecules?

Recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) is utilized in spinal fusions to induce osteoinduction. The intracellular signaling pathway activated by BMP-2 binding to its serine/threonine kinase receptor is primarily mediated by which of the following?

Nitrogen-containing bisphosphonates, such as alendronate, are a first-line treatment for osteoporosis. They cause osteoclast apoptosis by inhibiting which specific enzyme in the mevalonate pathway?

During embryonic skeletal development and fracture repair, multipotent mesenchymal stem cells must commit to the osteoblastic lineage. Which of the following transcription factors is the master regulator for osteoblast differentiation?

According to Perren's strain theory of fracture healing, the tissue that forms at a fracture site is dictated by the amount of interfragmentary strain. If the local mechanical strain is between 2% and 10%, which type of tissue will predominantly form?

Romosozumab is an anabolic pharmacological agent used to treat severe osteoporosis. It exerts its effect by binding to and inhibiting a specific glycoprotein, thereby activating the Wnt signaling pathway. What is the target of romosozumab?

A 65-year-old woman with severe osteoporosis is started on romosozumab, a monoclonal antibody that binds to sclerostin. What is the primary downstream effect of this medication on bone metabolism?

A 32-year-old man undergoes open reduction and internal fixation of a transverse radial shaft fracture with a compression plate. Radiographs at 8 weeks show no visible callus, but the fracture line is disappearing. What is the primary mechanism of bone healing occurring in this scenario?

In response to hypocalcemia, parathyroid hormone (PTH) is secreted into the bloodstream. Which of the following best describes the direct effect of PTH on the kidneys to restore serum calcium levels?

A 72-year-old woman with a history of multiple osteoporotic vertebral compression fractures is started on teriparatide. Which of the following best describes the mechanism of action of this medication?

A surgeon uses demineralized bone matrix (DBM) to augment a posterolateral lumbar fusion. Which of the following properties is characteristic of DBM but absent in synthetic calcium phosphate ceramics?

Sclerostin is a key negative regulator of bone mass. It functions by antagonizing the Wnt signaling pathway. Which cell type is the primary source of sclerostin in the skeletal system?

Which of the following bone graft substitutes is considered exclusively osteoconductive and relies entirely on the host bed for cellular and inductive components?

In a bridge plating construct for a comminuted diaphyseal fracture, increasing the working length of the plate (the distance between the closest screws on either side of the fracture) has what primary biomechanical effect?

Bone Morphogenetic Proteins (BMPs) play a crucial role in osteoinduction. Following the binding of BMPs to their serine/threonine kinase receptors, which intracellular signaling molecules are directly phosphorylated to translocate to the nucleus?