Determination of Radiographic Healing using the RUST Score and the Modified RUST in Femoral Shaft Fractures Treated with Intramedullary Nailing

Objectives: To determine and compare the reliability of both the Radiographic Union Scale for Tibial Fractures (RUST) and modified RUST when applied to assess bone healing in femoral shaft fractures treated with intramedullary nailing from January 2013 to December 2017 at a Level III Trauma Center in a tertiary government hospital. Methods: Eight observers were assigned randomly, namely two fellow orthopaedic consultants and six orthopaedic residents, to assess the femoral shaft x-rays of patients treated with intramedullary nailing using the Radiographic union scale for tibial fractures (RUST) and the newly created modified RUST. Two sets of x-rays in the anteroposterior and lateral views for their respective follow up periods, eighty six (86) sets in total, were used. These 86 sets of radiographs were primarily assessed by the raters within the 2nd week of August 2020 and final assessment was done within the 2nd week of September 2020. Results: Assessments of eighty six sets of radiographs showed that there is an excellent and essentially perfect agreement between all observers with the use of RUST and mRUST at 0.92 ICC (95% CI; 0.88-0.94) and 0.93 ICC (0.90-0.95), respectively and as stated by Portney et. al. (2009), an ICC of 0.90 to 0.99 is acceptable for use as a clinical measure. Conclusion: This study showed that the Radiographic Union Scale for Tibial Fractures (RUST) and the modified RUST possesses a high intra-observer and inter-observer agreement and variability that can both be clinically used as a tool for assessment of radiographic healing of fractures of the femoral shaft treated with intramedullary nailing. These two scoring systems also have nearly identical high reliability and reproducibility when their use is compared.