A prospective study identifying the sensitivity of radiographic findings and the efficacy of clinical findings in carpal navicular fractures.

Carpal navicular fracture is the most common wrist bone fracture. Improper diagnosis and inadequate treatment result in potentially serious complications, including delayed fracture union, pseudoarthrosis, avascular necrosis, and wrist instability ultimately leading to deformity and osteoarthritis. Initial radiographs do not always demonstrate a discernible fracture line. To better define the frequency of initially negative radiographs of the navicular associated with true navicular fractures, and to test the efficacy of the three clinical signs (snuffbox tenderness, pain with supination against resistance, and pain with longitudinal compression of the thumb toward the navicular), a prospective study of 85 patients who presented to the emergency department during a four-year period with a mechanism of injury suggesting possible navicular injury was conducted. Forty-five patients had no demonstrable fracture or instability on initial examination or during the follow-up period. Forty patients ultimately were shown to have navicular fractures. Patients with negative radiographs and positive clinical findings were reevaluated after ten to 14 days of immobilization. Thirty-two patients had fracture lines visible on initial radiographic examination, and eight had lucent fracture lines demonstrated after ten to 14 days of immobilization. Snuffbox tenderness had a sensitivity of 100% and a specificity of 98% for fracture; supination against resistance had a sensitivity of 100% and a specificity of 98%; and longitudinal compression of the thumb had a sensitivity of 98% and a specificity of 98%. Chi-square analysis revealed a P value less than .001 for each of the three clinical maneuvers. This study reports a 20% occurrence of initially false-negative radiographs, which is higher than previously reported.(ABSTRACT TRUNCATED AT 250 WORDS)