This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal system, Subject name: Radiology
[{'content': 'A 70 years old female is on treatment with Alendronate for 7 years for osteoporosis. Now she complains of pain in right thigh. What is the next investigation to be performed? \nSelect and explain. \nA. DEXA scan, B. X-ray, C. Serum vitamin D levels, D. Serum alkaline phosphate levels', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Long term use of Alendronate (Bisphosphonates) results in following radiological changes in patients presenting with tigh pain: Earliest change would be thickening coex femur (predominantly the lateral coex) Later it results in subtrochanteric fracture through the thickened coex with medial spike. Hence in this scenario the next investigation would be X ray to see for coical thickening and atypical subtrochanteric fractures.', 'role': 'assistant'}]