Biology, Genetics & Bone Healing MCQs

A 12-year-old boy presents with progressive muscle weakness, a waddling gait, and severe, aching leg pain. Radiographs demonstrate marked, symmetrical bilateral cortical thickening of the femoral and tibial diaphyses, sparing the metaphyses and epiphyses.

Which of the following medical treatments has been shown to provide significant symptomatic relief for this condition?

A 70-year-old man complains of progressive hearing loss and an increasing hat size. Laboratory studies show a markedly elevated serum alkaline phosphatase with normal serum calcium and phosphorus levels. Histologic examination of a bone biopsy reveals a characteristic "mosaic" pattern of lamellar bone. What is the primary cellular defect in this disease?

A 30-year-old woman presents with knee pain. Radiographs reveal an eccentric, lytic lesion in the distal femoral epiphysis extending to the subchondral bone. Biopsy confirms a giant cell tumor of bone. Denosumab therapy is considered for her locally aggressive disease. What is the mechanism of action of this drug?

A 60-year-old man presents with a painful, destructive, lytic lesion in his proximal femur. He has a history of a nephrectomy for clear cell renal carcinoma 3 years ago. The lesion is judged to be at high risk for an impending pathologic fracture, and prophylactic intramedullary nailing is planned. What preoperative intervention is highly recommended to minimize surgical morbidity?

A 14-year-old boy with a family history of multiple bony protuberances presents with painless bumps around his knees and shoulders. Radiographs show multiple pedunculated and sessile bone lesions pointing away from the joint lines, with cortex continuous with the host bone. Genetic testing reveals a mutation in the EXT1 gene. What is the normal function of the protein encoded by this gene?

A 68-year-old male presents with a pathologic proximal femur fracture. Workup reveals monoclonal gammopathy and Bence-Jones proteinuria. Bone marrow biopsy confirms the diagnosis.

What is the primary cellular mechanism driving the distinct osteolytic lesions seen in this disease process?

A 70-year-old man with left thigh pain is found to have the lesion shown in the provided imaging. Serum protein electrophoresis confirms a monoclonal gammopathy. Following prophylactic internal fixation with a locked intramedullary rod, which of the following medical therapies is most appropriate to decrease the risk of future pathologic fractures?

A 70-year-old man presents with left thigh pain. Serum protein electrophoresis reveals a monoclonal gammopathy. Radiographs and CT (Figures A and B) show a large lucent lesion in the peritrochanteric region. Which of the following adjuvant medical treatments is most appropriate postoperatively to decrease the risk of future skeletal-related events?

A 70-year-old man with multiple myeloma presents with a large lucent lesion in the peritrochanteric region of the left proximal femur, as shown in the imaging studies. He undergoes prophylactic internal fixation with a locked intramedullary rod. Which of the following adjuvant therapies is most appropriate to decrease the risk of future pathologic fractures in this patient?

A 4-year-old boy with a history of multiple low-energy fractures, blue sclerae, and dentinogenesis imperfecta is being evaluated. He has bowing of both femurs. A genetic panel confirms a mutation in the COL1A1 gene. Which of the following describes the mechanism of action of the first-line medical therapy used to decrease fracture burden in this condition?

A patient with symptomatic Paget's disease of the tibia is prescribed the first-line pharmacologic treatment to reduce bone pain and turnover. What is the primary cellular mechanism of action of this medication class?

Routine laboratory testing in an asymptomatic 65-year-old male reveals an isolated, marked elevation of serum alkaline phosphatase. Calcium, phosphorus, and GGT levels are completely normal. Radiographs of the pelvis show coarse trabeculations and cortical thickening. What phase of Paget's disease does this presentation most likely represent?

A 60-year-old male on long-term hemodialysis presents with diffuse bone pain. Radiographs demonstrate a 'rugger jersey' appearance of the spine. His labs show elevated PTH, low calcium, and high phosphorus. What is the primary pathophysiologic trigger for his skeletal disease?

Which of the following laboratory profiles most accurately differentiates primary hyperparathyroidism from secondary hyperparathyroidism?

A bone biopsy from the thickened, bowed tibia of a patient with Paget's disease demonstrates a characteristic mosaic pattern of lamellar bone with prominent, disorganized cement lines. What is the underlying primary cellular abnormality driving this disease process?

What is the primary cellular defect that initiates the pathogenesis of Paget's disease of bone?

A 62-year-old woman with chronic kidney disease presents with diffuse bone pain. Radiographs of her hands show subperiosteal bone resorption on the radial aspect of the middle phalanges.

What is the most likely primary driving mechanism for these osseous changes?

A 68-year-old woman with active Paget's disease of the right hemipelvis and femur is scheduled for a total hip arthroplasty due to severe secondary osteoarthritis. Which preoperative pharmacological intervention is highly recommended to reduce intraoperative blood loss?

A 65-year-old male presents with enlarging hat size, hearing loss, and bowing of the tibiae. Laboratory evaluation reveals an isolated, markedly elevated alkaline phosphatase with normal serum calcium and phosphorus. What is the primary cellular abnormality initiating this disease process?

A 68-year-old male with symptomatic Paget's disease of the right hip is scheduled for a total hip arthroplasty due to severe secondary osteoarthritis. To minimize severe intraoperative hemorrhage, which medical management is recommended prior to surgery?