An otherwise healthy 40-year-old African American man presented with pain and stiffness of both knees for 2 years. He was in active military duty until a month before presentation and had performed long road marches and had carried heavy equipment. He did not have visual or hearing disturbances and had no history of fractures. He did not have family history of bone disease, fractures or other medical conditions. Review of systems was unremarkable. On examination both knees were swollen with evidence of free fluid, and flexion was restricted with crepitus on passive movements. Complete blood count, renal functions, electrolytes, calcium …