Multicenter validation of the modified wu classification as a 3d triplanar framework for proximal tibiofibular fractures

Abstract Accurate evaluation of proximal tibiofibular fractures remains clinically challenging. This study aimed to evaluate the diagnostic applicability and compare the inter-observer reliability and intra-observer reproducibility of the novel modified Wu classification (mWC) against three established systems (AO/OTA, Schatzker, and Luo). A multicenter, retrospective study was conducted analyzing 320 independent proximal tibiofibular fracture cases (comprising 171 cases in males and 149 cases in females; mean patient age, 45.76 ± 15.82 years) treated between January 2010 and October 2023. Four independent observers of varying clinical expertise evaluated plain radiographs, 2D CT, and 3D reconstructions to classify the fractures across the four systems. A second blinded assessment was performed following a four-week washout period. Agreement was quantified utilizing Fleiss’ kappa and Cohen’s kappa coefficients. Traditional systems failed to adequately categorize 26.9% (86/320) of cases, whereas the mWC successfully achieved a 100% classifiability rate. For inter-observer reliability, the mWC demonstrated substantial agreement (κ = 0.616), outperforming the Luo (κ = 0.597), Schatzker (κ = 0.484), and AO/OTA (κ = 0.449) classifications. Regarding intra-observer reproducibility, the mWC showed substantial agreement (mean κ = 0.772), which was statistically secondary to the almost perfect agreement achieved by the Luo system (κ = 0.831), but remained superior to the substantial agreement demonstrated by the Schatzker (κ = 0.700) and AO/OTA (κ = 0.696) systems. Crucially, the specific structural sub-components of the mWC (column, region, and segment) consistently yielded substantial to almost perfect agreement across evaluations.The mWC represents a structured evaluative framework that addresses several morphological gaps of traditional systems for evaluating proximal tibiofibular fractures. By integrating 3D anatomical precision and effectively addressing complex fracture patterns with concomitant fibular involvement, the mWC provides a consistent, reproducible framework that expands taxonomic classifiability, potentially facilitates preoperative surgical planning, and supports the standardization of future clinical research.