H sign

The Honda sign (H sign / H pattern) is a term used to describe the appearances of bilateral sacral insufficiency fractures on a radioisotope bone scan.

Radiographic features

Sacral insufficiency fractures are usually vertically through the sacral alae, paralleling the sacroiliac joint, often with a transverse component - this pattern resembles the capital letter H, leading to the designation of the Honda sign / H sign / H pattern.

With the more common availability of MRI, radioisotope scans (technetium 99m HDP) are less commonly undertaken.

History and etymology

The name derives from the appearance of the Honda car manufacturer's logo (badge), with the H-shaped appearance representing the areas of increased radioisotope uptake in the sacral alae medial to the sacroiliac joints with a band connecting the bilateral areas of vertical uptake.