Biology, Genetics & Bone Healing MCQs

Teriparatide, a recombinant human parathyroid hormone (PTH 1-34) analog, is given via daily subcutaneous injection. This intermittent dosing strategy leads to net bone formation primarily through which direct cellular effect?

A 68-year-old woman on long-term alendronate therapy presents with chronic left thigh pain. Radiographs demonstrate lateral cortical thickening and a transverse radiolucent line in the subtrochanteric region of the femur. Which of the following describes the fundamental pathophysiology of this specific fracture type?

A 68-year-old woman with a 10-year history of alendronate use presents with chronic thigh pain. Radiographs reveal focal lateral cortical thickening and a transverse radiolucent line in the subtrochanteric region. What is the most appropriate prophylactic management?

A 72-year-old woman on long-term alendronate therapy presents with a displaced subtrochanteric fracture of the right femur after a mechanical fall from standing height. She reports a 3-month history of left anterior thigh pain. Left femur radiographs reveal lateral cortical thickening and a transverse radiolucent line. What is the recommended management for the contralateral (left) limb?

A 65-year-old woman on long-term alendronate therapy presents with an atraumatic subtrochanteric femur fracture. Which of the following radiographic features is considered a hallmark of a bisphosphonate-related atypical femur fracture?

A 65-year-old woman, who has been taking alendronate for 12 years, presents with a low-energy transverse subtrochanteric femur fracture. Radiographs show lateral cortical thickening and a medial spike. Following cephalomedullary nailing of the fracture, what is the most appropriate pharmacological recommendation?

Sclerostin is a key regulatory glycoprotein secreted by osteocytes to inhibit bone formation. Its mechanism of action involves directly antagonizing which of the following intracellular signaling pathways?

According to Perren's strain theory of fracture healing, which of the following tissues can tolerate the highest level of interfragmentary strain before mechanical failure?

An infant presents with diffuse osteosclerosis and recurrent fractures. Genetic testing reveals a mutation in the CLCN7 gene. This condition primarily affects which of the following cellular mechanisms?

Bone morphogenetic protein 2 (BMP-2) stimulates osteoblast differentiation. Upon binding to its serine/threonine kinase receptor, which intracellular signaling molecules are directly phosphorylated to translocate to the nucleus?

Fibroblast growth factor 23 (FGF-23) plays a critical role in mineral homeostasis. Which of the following accurately describes its primary cellular source and its main renal effect?

Denosumab is highly effective in the management of osteoporosis and giant cell tumors of bone. It exerts its therapeutic effect by mimicking the physiological function of which endogenous molecule?

Cleidocranial dysplasia is characterized by hypoplastic clavicles, delayed cranial suture closure, and supernumerary teeth. It is caused by a genetic mutation in the master transcription factor for osteoblast differentiation. Which gene is affected?

Primary bone healing occurs under conditions of absolute stability without radiographically visible callus formation. Which of the following is the key microscopic mechanism driving this process?

Parathyroid hormone (PTH) regulates serum calcium homeostasis. Which of the following accurately describes the effect of intermittent, low-dose exogenous administration of PTH (e.g., teriparatide)?

A researcher is evaluating markers of bone turnover in patient serum. Which of the following markers is considered the most specific indicator of mature osteoblast activity and bone formation?

A pediatric patient with X-linked hypophosphatemic rickets presents with progressive lower extremity bowing. Pathophysiologically, this condition is driven by a mutation in the PHEX gene, leading to the overactivity of which regulatory hormone?

A 65-year-old woman is prescribed a medication for osteoporosis that works by binding to and inhibiting RANKL. What is the primary cellular effect of this medication?

A 40-year-old man sustains a transverse femoral shaft fracture treated with a rigid locked intramedullary nail. Which type of bone healing will predominate at the fracture site?

Which of the following signaling pathways is directly stimulated by the binding of bone morphogenetic protein-2 (BMP-2) to its cell surface receptor on mesenchymal stem cells?