Abstract
Objective: Avascular Necrosis happens to be one of the most common diseases in patients presenting with a chronic painful hip. We have evaluated these patients in the background of demographic details.
Material and Method: Prospective study evaluating 319 patients using conventional X-ray and MRI. Imaging findings were evaluated and staging of AVN was done on both modalities. Demographic details were documented in the background of clinical settings.
Results: 10.6% of the cases were diagnosed on X-Ray (34 patients). Sequential MRI examination picked up 21% MRI (68 patients). X-ray was missing the diagnosis of AVN in nearly 50% of the cases. 46% of the cases (147 patients) were from age groups ranging from 20-40 years, followed by older patients. It is comparatively rare in young, and if present is associated with other systemic diseases. 60% of the patients were male and 40% of the patients were females. Bilateral hip pain was present in 31% of the cases (100 patients). Right side involvement (37%) was slightly more common than left (32%) in cases with unilateral hip pain. Commonly encountered imaging findings associated were femoral head marrow oedema in 59 patients (87%), double-line sign in 54 patients (79%), subchondral cysts in 42 patients (62%), followed by joint effusion, joint space reduction, femoral head altered contour, femoral head fragmentation with collapse.
Conclusion: X-ray alone can miss up to 50% of the cases of Avascular Necrosis of the femoral head, especially in milder and potentially salvageable cases. Correct imaging interpretation and grading make the role of MRI pivotal.

Key words: AVN, X-ray, MRI, Bone Marrow Edema, Joint space reduction, Effusion, Femoral head altered contour, Femoral head fragmentation with collapse