Evaluating reliability of the RUST score in diaphyseal Tibia fractures: A collaborative assessment by orthopaedic surgeons and radiologists

Abstract

Introduction: Fractures of the diaphysis of the tibia are quite common. Whelan et al., in 2010 proposed the Radiological Union Score of Tibia (RUST) to evaluate fracture healing based on whether a fracture line and bridging callus are present on each cortex as noted in AP and lateral views of a radiograph. The main objective of this study was to evaluate interobserver and intraobserver variation of the RUST score for tibial diaphysis fractures managed by intramedullary interlocking nails when applied by orthopaedic surgeons, radiologists, and interns. Methods: A collection of 115 radiographs comprising diaphyseal tibia fractures that were treated with intramedullary nailing between January 2021 and July 2022. Eight observers (two orthopaedic surgeons, two radiologists, and four interns) independently applied the RUST score for each radiograph. Clinical data related to the radiographs such as duration since surgery and medical history were not disclosed to the observers. Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) were used to measure the reliability of the RUST score. Interobserver reliability was measured by examining the scores of the eight observers from the first assessment. In order to determine the intraobserver reliability, each reviewer was instructed to reassess the radiographs after a period of 4 weeks following the original evaluation. Results: The RUST score of the 115 radiographs varied from 4 to 12. The mean scores in the first assessment and second assessment were 8.47 ± 2.75 and 8.68 ± 2.65, respectively. Overall, there was high interobserver agreement among all observers (ICC, 0.95; 95% CI, 0.93–0.96). The intraobserver reliability among all the observers was good (ICC, 0.81; 95% CI, 0.79–0.84). Conclusion: The RUST score has excellent interobserver and intraobserver reliability for tibial diaphysis fractures fixed with intramedullary nails, showing exceptional consistency between orthopaedic surgeons and radiologists.