TODAY'S TWO SIGNS TODAY'S TWO SIGNS 106 SA JOURNAL OF RADIOLOGY • December 2007 TODAY'S TWO SIGNS Scapholunate instability (SLI) (also known as scapholunate dissociation or rotary subluxation of the scaphoid) is caused by a tear in the inter- osseous ligaments of the lunate, scaphoid and the capitate bone with a tear in the dorsal radiocarpal ligaments by acute dorsifexion injury or fractures of the distal radius.1,2 The patient complains of wrist pain, weakness of grip and a clicking sensation in the wrist. SLI is diagnosed with a gap or separation between the scaphoid and the lunate bones on a posterior anterior wrist X-ray. More than 2 mm is suspicious and 4 mm or more is diagnostic of SLI.1,2 This scaphoid- lunate gap is also referred to as the ‘Terry Thomas’ sign (Fig. 1) refer- ring to the distinctive gap between the upper incisors of the late British comedian. There is in addition foreshortening of the scaphoid, causing the cor- tical margin of the distal pole to become parallel to the central axis of the X-ray and appear as a ring called the the ‘ring sign’ (Fig. 1). The gap is bet- ter demonstrated in ulnar deviation or clenched-hand position (Fig. 2).1,2 Treatment is dependent on the symptoms, ranging from rest to carpal fusion. 1. Rogers LF. Radiology of Skeletal Trauma, 2nd ed. Edinburgh: Churchill Livingstone,.1992: 927-929. 2. Hudson TM, Caragol WJ, Kaye JJ. Isolated rotatory subluxation of the carpal navicular. AJR 1976; 126: 601-611. `Terry Thomas´ sign and the `ring sign´ of scapholunate instability A S Bajwa, MB BS, FCS (SA) Ortho Brenthurst Life Health Clinic, Parktown, Johannesburg A K Bajwa, MB BS, FCRad (Diag) SA Department of Diagnostic Radiology, Chris Hani Baragwanath Hospital and University of the Witwatersrand, Johannesburg Fig. 2. The gap is more pronounced in the clenched hand-position. Fig. 1. Posterior anterior wrist X-ray demonstrating the widened gap between the scaphoid and the lunate bone ‘Terry Thomas’ sign. There is in addition foreshortening of the scaphoid with a ‘ring sign’. Underlying osteodegenerative changes are noted; these and the radio carpal joints are due to longstanding SLI. pg106-107.indd 106 12/11/07 2:21:20 PM TODAY'S TWO SIGNS TODAY'S TWO SIGNS 107 SA JOURNAL OF RADIOLOGY • December 2007 The presence of faeculant material (colonlike material mixed with gas resembling stool) in the lumen of the distended (more than 2.5 cm) small bowel on computed tomography (CT) is defined as small bowel faeces sign (Fig. 1).1 It is due to intraluminal stagnation of the enteric contents complicated by bacterial overgrowth and water absorption. It is an uncommon but highly specific sign of small bowel obstruc- tion (SBO) on CT scan of the abdomen, particularly in patients with low-grade or intermittent obstruction.2 The adjacent transition zone and the distal collapsed bowel loops indicate the level of obstruction. The most common cause of the SBO is adhesions. Other common causes are inflammation, tumours and hernias. Small bowel faeces sign may also indicate severe metabolic or infectious pathology of the small bowel. The clinical signs of SBO are difficult to distinguish from local or generalised paralytic ileus; therefore an early radiological diagnosis is very important. 1. Mayo-Smith WW, Wittenberg J, Bennett GL, Gervais DA, Gazelle GS, Mueller PR. The CT small bowel faeces sign: description and clinical relevance. Clin Radiol 1995; 50: 765-767. 2. Catalano O. The faeces sign: a CT finding in small bowel obstruction. Radiology 1997; 37: 417-419. Small bowel faeces sign Amarjit Kaur Bajwa, MB BS, FCRad (Diag) SA Department of Diagnostic Radiology, Chris Hani Baragwanath Hospital, University of the Witwatersrand, Johannesburg Fig. 1. Axial CT in a 22-year-old female patient with history of Crohn dis- ease demonstrating the small bowel faeces sign in a distended ileal loop. Adjacent transition zone with collapsed distal small bowel is seen. pg106-107.indd 107 12/11/07 2:21:20 PM