Which of the following is the most sensitive investigation for the condition shown in the following X-ray?

Ans. A. MRIThe X-ray shows flattening of the femoral head and degenerative changes associated with the Avascular necrosis of femoral head. The most sensitive and specific investigation for avascular necrosis is MRI. MRI allows accurate assessment of the extent of involvement and can also identify associated bone marrow changes. X-ray may be normal in the early stages of the disease.Avascular necrosis or osteonecrosis of the femoral head occurs because of an interruption in the blood supply to femoral head which causes bone death. This leads to collapse of the femoral head causing secondary osteoarthritis subsequently.