Biology, Genetics & Bone Healing MCQs

Bone morphogenetic proteins (BMPs) are utilized in spine surgery for their potent osteoinductive properties. They primarily exert their effect by binding to cell membrane receptors, which subsequently phosphorylates which family of intracellular signaling proteins to transcribe osteogenic genes?

A 65-year-old man sustains a pathologic fracture of the humerus. Radiographs show multiple "punched-out" lytic lesions. Laboratory work reveals hypercalcemia, anemia, and an IgG kappa monoclonal spike. The severe osteolysis seen in this condition is primarily mediated by the neoplastic cells secreting factors that heavily upregulate which pathway?

A 70-year-old female with osteoporosis is prescribed a nitrogen-containing bisphosphonate. This medication inhibits bone resorption primarily by inhibiting which of the following intracellular targets within the osteoclast?

A 35-year-old sustains a transverse radius shaft fracture that is treated with open reduction and internal fixation using a dynamic compression plate to achieve absolute stability. What is the primary mechanism of bone healing expected in this scenario?

A 55-year-old patient presents with diffuse bone pain and proximal muscle weakness. Laboratory evaluation reveals hypocalcemia, hypophosphatemia, elevated alkaline phosphatase, and elevated parathyroid hormone. Radiographs show Looser zones in the femoral neck. What is the primary histopathologic defect?

Parathyroid hormone (PTH) plays a critical role in calcium homeostasis by modulating bone turnover. By what mechanism does PTH indirectly stimulate osteoclastic bone resorption?

A 65-year-old male with a history of advanced prostate carcinoma presents with severe back pain. Radiographs demonstrate multiple dense, osteoblastic lesions in the lumbar vertebrae. Prostate cancer cells predominantly stimulate this osteoblastic response by secreting which of the following factors?

A surgeon plans to utilize recombinant human bone morphogenetic protein-2 (rhBMP-2) on a collagen sponge carrier to augment healing in a tibial nonunion. At the cellular level, BMP-2 promotes osteoinduction primarily by initiating an intracellular signaling cascade mediated by which proteins?

A pediatric patient with frequent fractures and cranial nerve palsies is evaluated. Radiographs demonstrate a diffuse 'bone-within-bone' appearance. The primary pathophysiologic defect in this condition is characterized by a failure of which of the following?

A 68-year-old woman sustains an atypical subtrochanteric femur fracture after taking alendronate for 10 years. What is the primary cellular mechanism of action of this class of medication?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized to augment spinal fusion. BMPs primarily induce bone formation by binding to cell surface receptors and stimulating which of the following intracellular signaling pathways?

A 65-year-old male presents with bone pain and hypercalcemia. Radiographs demonstrate multiple 'punched-out' lytic lesions in the skull and long bones.

The profound lack of bone formation in the lytic lesions of this disease is primarily mediated by tumor cell secretion of which factor?

A midshaft tibia fracture is treated with a reamed, statically locked intramedullary nail. Which type of bone healing predominates in this biomechanical environment?

A 30-year-old female is diagnosed with an advanced giant cell tumor of bone in the distal femur. Denosumab is recommended for neoadjuvant treatment. What is the exact mechanism of action of this medication?

During the evaluation of a patient with suspected osteomalacia, vitamin D metabolism is reviewed. Which enzyme is directly responsible for the conversion of 25-hydroxyvitamin D to its most active hormonal form, 1,25-dihydroxyvitamin D?

A surgeon plans to use demineralized bone matrix (DBM) to augment a tibial nonunion repair. Compared to an autologous iliac crest bone graft, DBM inherently possesses which of the following biologic properties for bone healing?

A 40-year-old man sustains a fracture of the tibial shaft and undergoes reamed intramedullary nailing. Which of the following phases of fracture healing is most directly enhanced by the mechanical stability provided by the nail while still allowing controlled micromotion?

A 32-year-old woman presents with a lytic lesion in the distal femur. Biopsy confirms a giant cell tumor of bone. She is treated with denosumab to downstage the tumor prior to surgery. What is the mechanism of action of this medication?

Following a diaphyseal fracture, rigid fixation with compression plating is performed, resulting in absolute stability. By which of the following primary mechanisms will the fracture heal?

A 65-year-old woman receives intravenous zoledronic acid for the treatment of severe osteoporosis. At the cellular level, this medication inhibits osteoclast-mediated bone resorption primarily by inhibiting which of the following enzymes?