Honda (‘H’) Sign

Stress fractures and other stress phenomena are often detected with radionuclide bone scans before changes are evident on plain radiographs. The plain radiographic appearance may be very subtle or non-specific. In 1983, Todd Ries ¹ (Baylor University Medical Center) reported a characteristic pattern, seen on radionuclide bone scans, in four patients with sacral insufficiency fractures. ‘In each case, bone scans showed a characteristic H-shaped uptake pattern, with the central portion of radionuclide over the sacrum and the remainder over the sacroiliac joints.’ The H-shaped pattern he described has become known as the Honda sign. The horizontal and vertical lines of increased uptake seen on the bone scan (Figure 1) indicate the areas of insufficiency fracture and resemble the letter H of the Honda automobile emblem (Figure 2). These insufficiency fractures can be a cause of pain in cancer patients. The fractures should not be confused with areas of metastatic disease. The Honda sign can now also be detected on computerized tomography and magnetic resonance imaging scans. Figure 1 ‘Posterior view of the pelvis shows the characteristic H-shaped pattern of uptake.’ Reprinted from Ries’. Detection of osteoporotic sacral fractures with radionuclides. <italic>Radiology,</italic> 1983, 146, 783–5 with permission of the RSNA https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig41_1_B.jpg"/> Figure 2 Honda automobile ‘H’ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig41_2_B.jpg"/>