Avascular necrosis of left hip joint with hip joint effusion-ARCO Stage III

Left femoral head shows deformed contour with surface flattening and depression for more than 4 mm along the supero-lateral aspect. There is moderate marrow oedema in femoral head which is extending into the neck region. The reactive interface line is evident in the femoral head. On T2WI, double line sign is present with serpiginous peripheral dark and inner bright line seen. The area of involvement is >30 % of the femoral head and the crescent encompasses >30 of the maximum circumference of the femoral head. Mild effusion is seen in the hip joint. Thickening of the hip joint capsule is seen. Marginal osteophytes are seen at the acetabular margins. Degenerative cysts are seen in the femoral head.

Right femoral head shows normal appearance. No marrow edema is seen. The femoral head shows normal smooth rounded contour without any significant flattening.

The acetabular labrum is normal. The rest of the pelvic bones reveal normal signal intensity.

Bilateral sacro-iliac joint space is normal.

The urinary bladder is normal.
CT LEFT HIP JOINT:
Left hip joint
It shows multiple areas of sclerosis and lucency in the femoral head with surface irregularity with flattening and depression. Degenerative changes are seen in the left hip joint.

Avascular necrosis of left hip joint with hip joint -ARCO Stage III. The area of involvement is >30 % of the femoral head and the crescent encompasses >30% of the maximum circumference of the femoral head. > 4 mm surface depression -grade C. Secondary degenerative changes are seen.
Normal right femoral head.