http://www.gentili.net/signs/

It presents images and information related to common and not so common signs used in Musculoskeletal Radiology, which can be reviewed by sign name (from Absent bow tie sign to Vacuum phenomenon), pathological diagnosis or locations (from Ankle to Wrist). The signs are illustrated with radiographs and diagrams. The references are linked to PubMed, allowing access to the abstract, if available.