X-ray tangential view in diagnosis of fracture of the fifth metatarsal base

Abstract

Objective To introduce a new X-ray projection in diagnosis of fracture of the fifth metatarsal base. Methods Included in this study were 97 patients who had undergone foot X-ray ex-amination at anteroposterior, oblique and tangential views from October 2014 to July 2015. They were 39 males and 58 females, with an average age of 46.2 years (from 15 to 80 years). Altogether, 43 left sides and 54 right sides were involved. In the tangential projection, the patients took supine position, kept the lower leg at extension and internal rotation of 10 to 20 degrees on the examination bed, relaxed the ankle on a resting position, kept the tube center to the fifth metatarsal base and perpendicular-to-table alignment. The fracture displacements were measured on the X-ray films of the 3 views. The Mehlhorn classifications and displace-ments observed on the tangential view X-ray films were compared with those on the X-ray films of anteropos-terior and oblique views. Results The fracture line was evident on the tangential view X-ray films of all the 97 patients but on the anteroposterior and oblique view films of 91 cases (93.8%). The mean fracture displacement on the tangential view films was greater than that on the anteroposterior and oblique view films. In the Mehlhorn classification, the anteroposterior view films revealed 59 cases of type A and 35 cases of type B; the oblique films showed 56 cases of type A and 38 cases of type B; the tangential view films found 35 cases of type A and 59 cases of type B. The tangential view films showed a significantly higher rate of diagnosis of type B fractures than images of the other 2 views (P<0.001). Conclusions The tangential pro-jection X-ray has an important value in the diagnosis of the fifth metatarsal base fracture. Patients suspected of the fracture should take X-ray examination at anteroposterior, oblique and tangential views. Key words: Metatarsal bones; Fractures, bone; Radiography; Diagnosis