The retroisthmic cleft. Scintigraphic appearance and clinical relevance in patients with low back pain.

This article describes the scintigraphic appearance of both a symptomatic and asymptomatic retroisthmic cleft in two athletes with low back pain. This lesion, which involves the lamina, is the least common of the neural arch defects of which spondylolysis is the most common. The anatomy of the lesion is discussed and illustrated. The literature about the possible cause of these lesions is reviewed. The report emphasizes the valuable role of radionuclide bone imaging in patients who have pain of potentially osseous origin, and who have a lesion of uncertain physiologic significance seen on an anatomic study such as a plain x-ray, CT scan, or MRI.