Foreign bodies. The broken needle tip in the third finger of the patient on the left is easily seen on this radiograph. Radiographs are useful when a suspected foreign body is expected to be metallic or glass, as these are radio-opaque. However, a common cause of foreign bodies in the hands is splinters of wood, which will not show up on a radiograph. A little known fact amongst clinicians is that these are usually very easy to see using ultrasound – like the linear echogenic splinter in the tip of a fifth finger, shown on the ultrasound image on the right (arrows).