Prediction of secondary displacement in Colles' fracture.

In a prospective study, 645 consecutive Colles' fractures treated conservatively were followed until union. The fractures subsequently lost some of their manipulated position during the immobilization period. However, the anatomical end result was significantly improved compared with the initial deformity. The mean shortening of the radius during plaster-cast treatment was 3 mm, and the mean increase of dorsal angulation was 7 degrees. Multiple regression analyses showed that initial dorsal angulation, age, and Older type were important predictor variables for the end result of dorsal angulation. Initial radial length, age and initial dorsal angulation were of importance for the end result of radial length. The strongest linear relationship was found between the end result of radial length and the initial radial length (r = 0.67). This may indicate that the patients who will malunite with radial shortening are those with significant radial axial shortening at the initial presentation. Thus, these patients should be treated with a more stable fixation device.