Three-point index in predicting redisplacement of extra-articular distal radial fractures in adults

Introduction: In distal radial fractures in adults, factors affecting instability have been investigated in many studies in an effort to shorten the preoperative waiting period for the fractures requiring surgery. Numerous factors, aside from the alignment-related indices, have been searched to predict redisplacement. Unlike as in paediatric counterparts, the casting technique and casting-related indices have not been appropriately considered in adults. The aim of this study was to determine the impact of the various previously investigated factors in addition to casting technique-related indices such as threepoint index, cast index, padding index and gap index, in predicting the risk of redisplacement of extraarticular distal radial fractures in adults and the presence of the ulnar deviation of the cast. Patients and methods: Seventy-five patients over 18 years who were treated with a cast in our emergency department within 24 h after a displaced distal radial fracture, were recruited into the study. Age, alignment-related indices, cast-related indices, extent of the ulnar deviation of the cast, having a nonanatomical reduction, co-existing ulnar fracture, dorsal comminution and obliquity of the fracture line were investigated. Casting technique according to three-point index, obliquity of the fracture line, degree of the ulnar deviation of the cast, and reduction accuracy were the significant factors affecting redisplacement. Results: The three-point index had a sensitivity of 95.8%, specificity of 96.1%, positive predictive value of 92%, and negative predictive value of 98% in predicting redisplacement. Logistic regression revealed that having an inadequate cast according to the three-point index (p < 0.001), degree of obliquity of the fracture line (p = 0.018), decreased ulnar deviation of the cast (p = 0.002), and having a non-anatomical reduction (p = 0.029) were the significant predictive factors in redisplacement. Conclusions: Our results suggest that the casting technique plays a major role in the success of conservative treatment, which can best be examined with the three-point index. Ulnar deviation of the cast and fracture obliquity are the other dominant factors affecting redisplacement.