Reliability of a Modified Watson-Jones Classification for Tibial Tubercle Fractures in Children

Objectives: The first case report describing a pediatric fracture of the tibial tubercle was published in 1852 in the Medical Times and Gazette, a Journal of Medical Science, literature, criticism, and news. A century later, in 1955, Sir Watson-Jones introduced the first classification system for this fracture. Despite the existence of several classification systems for pediatric tibial tubercle fractures in the medical literature, a crucial aspect of their validation-reliability and reproducibility-has not yet been systematically evaluated.

Methods: In this study, a modified Watson-Jones (mWJ) classification system of tibial tubercle fractures in children was assessed for intraobserver and interobserver variability. Using the mWJ classification, 3 board-certified pediatric orthopaedic surgeons and 3 orthopaedic surgery residents, classified thirty tibial tubercle fractures based on anteroposterior and lateral radiographs on 2 separate occasions in a 2-week duration. Further comparison was made to evaluate the impact of advanced imaging, specifically computed tomography or magnetic resonance imaging, on diagnostic reliability and reproducibility.

Results: The study found substantial intraobserver reliability of the mWJ classification based on radiographs alone, with a Cohen weighted kappa (κ w ) coefficient of 0.733. When advanced imaging was utilized, the reliability of the classification improved to κ w = 0.783. Similarly, interobserver reliability demonstrated substantial consistency among observers when using radiographs alone (κ w = 0.69) and improved agreement with advanced imaging (κ w = 0.75). Notably, there was no significant difference in reliability scores between senior-level attendings and residents when analyzed as separate groups.

Conclusion: Fracture classification systems are clinically relevant tools that help organize and transfer knowledge efficiently, provide treatment guidance, propose prognostic expectations, and improve communication in academic literature. The present study demonstrated substantial reproducibility of an mWJ fracture classification system both between and within individual surgeon raters.

Level of evidence: Level III-diagnostic.