Clinical scaphoid score (CSS) to identify scaphoid fracture with MRI in patients with normal x-ray after a wrist trauma

INTRODUCTION: The aim of this study was to compare a combination of three commonly used tests to identify scaphoid fractures with MRI in patients with normal x-ray after a wrist trauma. PATIENTS AND METHODS: This prospective MRI study included patients between 18 years and 49 years, who attended the Emergency Department, Bergen, Norway after sustaining an acute wrist trauma within the previous week. Initial x-rays of the wrist were normal. MRI was done within a median of 1 day after the trauma. The study period lasted 1 year. The patients were examined with three commonly used clinical scaphoid tests; tenderness in the anatomical snuffbox with the wrist in ulnar deviation (3 points), tenderness over the scaphoid tubercle (2 points) and pain upon longitudinal compression of the thumb (1 point). The clinical scaphoid score (CSS) is a sum of these points, which was compared with MRI verified fracture of the scaphoid. RESULTS: We included 154 patients with wrist sprain and normal x-rays; 13 had occult scaphoid fracture. A CSS of 4 or more was the only statistically significant 'cut-off' value to identify occult scaphoid fractures (p<0.05). Diagnostic sensitivity increased with more experienced Emergency Department doctors. CONCLUSIONS: If a patient with wrist pain after injury and normal x-ray has a CSS≥4 (pain in the anatomical snuffbox in addition to pain at scaphoid tubercle or longitudinal compression or both) we recommend MRI. A CSS <4 has a negative predictive value of 96%, which makes scaphoid fracture unlikely.