Biology, Genetics & Bone Healing MCQs

A 3-year-old boy presents with progressive bowing of his legs and short stature. Labs show normal serum calcium, normal PTH, low serum phosphorus, and elevated alkaline phosphatase. Which of the following is the most likely pathophysiologic mechanism for his disease?

A 6-year-old boy presents with progressive bowing of the legs and short stature. Laboratory tests show normal serum calcium, profoundly low serum phosphate, normal PTH, and normal 25-hydroxyvitamin D levels. A mutation in the PHEX gene is identified. The primary pathophysiology of his bone disease is driven by the overproduction of:

A 32-year-old female is diagnosed with an expansile, lytic Giant Cell Tumor (GCT) in the distal femur. Because the lesion is large and abuts the subchondral bone, she is placed on neoadjuvant denosumab therapy to facilitate joint-salvage surgery. Denosumab functions by binding directly to which of the following?

A 65-year-old man with progressive cranial enlargement and anterior bowing of his tibiae is diagnosed with Paget's disease of bone. The underlying cellular abnormality involves hyperactive osteoclasts. Familial forms of this condition are most strongly associated with a mutation in which of the following genes?

A 68-year-old woman is diagnosed with multiple myeloma after presenting with diffuse bone pain and 'punched-out' lytic lesions on radiographs. The profound osteolysis seen in multiple myeloma is predominantly driven by myeloma cell-induced upregulation of which of the following combinations of factors?

A 22-year-old patient presents with recurrent fractures, anemia, and cranial nerve palsies. Radiographs demonstrate diffusely dense bones and a "rugger jersey" spine. The underlying pathophysiology of this condition is most commonly due to a primary defect in which of the following?

A 55-year-old female presents with diffuse, dull bone pain and proximal muscle weakness. Laboratory studies reveal low serum calcium, low serum phosphate, elevated alkaline phosphatase, and elevated parathyroid hormone (PTH). Radiographs show bilateral pseudofractures in the femoral neck. What is the most likely diagnosis?

A 68-year-old woman with severe osteoporosis is treated with denosumab. This biologic agent exerts its anti-resorptive effect by binding directly to which of the following molecular targets?

Bone morphogenetic proteins (BMPs), particularly BMP-2 and BMP-7, are utilized to augment fracture healing and spinal fusions. These osteoinductive proteins primarily exert their cellular effects by signaling through which of the following intracellular pathways?

An 80-year-old female with severe osteoporosis is started on teriparatide therapy. This medication, administered as a daily subcutaneous injection, increases bone mineral density primarily through which of the following mechanisms?

According to Perren's strain theory, what is the maximum amount of interfragmentary strain that allows for primary bone healing to occur without callus formation?

A 45-year-old woman with a history of Roux-en-Y gastric bypass presents with diffuse bone pain and proximal muscle weakness. Laboratory evaluation reveals low serum calcium, low phosphorus, elevated alkaline phosphatase, and elevated parathyroid hormone (PTH). What is the most likely diagnosis?

A 30-year-old woman is diagnosed with an expansive, eccentrically located, lytic lesion in the distal femur extending to the subchondral bone. Biopsy confirms a Giant Cell Tumor of bone. If medical therapy is considered, which molecular pathway is targeted to inhibit the progression of this tumor?

A 4-year-old girl is evaluated for recurrent fractures with minimal trauma. Examination reveals blue sclerae and mild hearing loss. A defect in which of the following processes is primarily responsible for her condition?

A surgeon utilizes demineralized bone matrix (DBM) during a spinal fusion. Which of the following properties does DBM inherently possess to facilitate bone formation?

A 4-year-old boy presents with a history of recurrent fractures, blue sclerae, and early-onset hearing loss. A structural defect in which of the following molecular processes is the primary pathophysiology?

A 65-year-old man presents with increasing hat size and bilateral hip pain. Radiographs reveal extensive cortical thickening and coarsened trabeculae. Bone biopsy demonstrates a mosaic pattern of lamellar bone. What is the primary cellular defect initiating this condition?

A 5-year-old boy is diagnosed with X-linked hypophosphatemic rickets. Which of the following laboratory profiles is most characteristic of his untreated condition?

A 30-year-old woman presents with a lytic, epiphyseal-metaphyseal lesion in her proximal tibia. Biopsy reveals multinucleated giant cells intermixed with mononuclear stromal cells. Systemic therapy with denosumab is considered. What is the specific target of this medication?