Biology, Genetics & Bone Healing MCQs

Bone morphogenetic proteins (BMPs) are extensively used in orthopedics for their osteoinductive properties. Which of the following best describes the intracellular signaling pathway activated directly upon BMP binding to its cell surface receptor?

A 35-year-old female presents with a lytic epiphyseal lesion of the distal femur. Biopsy confirms a Giant Cell Tumor (GCT) of bone. If medical therapy is initiated, which molecular pathway is targeted by the drug of choice?

Which type of bone healing occurs under conditions of absolute stability, such as following rigid compression plating of a simple transverse radius fracture?

A 4-year-old boy presents with profound bowing of the lower extremities and a waddling gait. Laboratory studies reveal normal serum calcium, significantly decreased serum phosphate, elevated alkaline phosphatase, and normal parathyroid hormone levels. What is the most likely genetic mutation responsible for this condition?

Which of the following pharmacological agents acts by primarily binding and inhibiting sclerostin, thereby upregulating the Wnt/beta-catenin signaling pathway to dramatically increase osteoblastic bone formation?

A 4-month-old infant presents with recurrent fractures, cranial nerve palsies, and diffuse skeletal sclerosis on radiographs. Genetic testing reveals a mutation in the TCIRG1 gene. Which of the following is the primary pathophysiologic mechanism responsible for this condition?

A 65-year-old female presents with persistent, dull, aching back pain. Radiographs show a compressive fracture of L4 and multiple 'punched-out' lytic lesions in her skull. Serum protein electrophoresis reveals a monoclonal spike. Which of the following factors is primarily responsible for the osteolytic bone destruction seen in this disease process?

A 35-year-old female presents with knee pain. Radiographs reveal an eccentrically located, lytic epiphyseal lesion extending to the subchondral bone in the proximal tibia. Biopsy shows multinucleated giant cells interspersed with mononuclear stromal cells. Treatment with Denosumab is considered. Denosumab targets which of the following to arrest tumor progression?

Which of the following conditions is an absolute requirement for primary (direct) bone healing to occur without the formation of a cartilaginous callus?

A 32-year-old female presents with knee pain and swelling. Radiographs show an eccentric, lytic epiphyseal lesion in the distal femur without a sclerotic rim. Biopsy confirms a giant cell tumor of bone. If medical therapy is considered, which of the following describes the mechanism of the most appropriate targeted agent?

Bone morphogenetic proteins (BMPs) are osteoinductive growth factors belonging to the TGF-beta superfamily. Which of the following BMPs is an FDA-approved biologically active protein used as an adjunct in acute open tibia fractures?

Which cytokine is secreted by osteoblasts to directly stimulate osteoclast differentiation by binding to its specific receptor on the surface of osteoclast precursors?

A 55-year-old female with short bowel syndrome presents with diffuse bone pain and symmetric Looser zones on radiographs. What is the expected laboratory profile for her condition?

According to Perren's strain theory, providing absolute fracture stability with less than 2% interfragmentary strain will promote which specific type of bone healing?

Bone morphogenetic proteins (BMPs) initiate intracellular signaling by binding to specific membrane-bound serine/threonine kinase receptors. This directly leads to the phosphorylation and nuclear translocation of which intracellular transcription factors?

Which of the following bone morphogenetic proteins (BMPs) is currently FDA-approved as an alternative to autogenous bone graft for use in acute, open tibial shaft fractures treated with an intramedullary nail?

Demineralized bone matrix (DBM) is widely used in orthopedic surgery as a bone graft substitute. Which of the following best describes the inherent biologic properties of DBM?

A 65-year-old woman with a distal radius fracture is diagnosed with osteoporosis and started on an oral bisphosphonate. What is the primary mechanism of action of this medication class?

During embryonic development, the limb bud grows in three different axes. Which signaling center and its corresponding molecule are primarily responsible for the anteroposterior (radioulnar) patterning of the limb, dictating the development of the thumb to the small finger?