Are Distal Radius Fracture Classifications Predictive of Instability? A Prospective Cohort Study

Abstract The success of treatment for distal radius fractures (DRFs) fundamentally depends on the proper identification of fracture instability. However, there is no evidence-based consensus on the best classification system for detecting unstable fractures. This study aims to evaluate the effectiveness of the main DRF classification systems in predicting instability during conservative treatment, as well as to assess their reproducibility and identify additional factors associated with loss of reduction. A prospective cohort study involving 121 adult patients with conservatively treated DRF. Initial radiographs were independently classified by three hand surgeons according to six systems: AO/ASIF, Fernandez, Frykman, Universal, IDEAL, and LaFontaine criteria. Instability was defined as loss of reduction within 8 weeks of follow-up, based on standardized radiographic parameters. Predictive analysis for instability and intraclass correlation coefficients were applied to assess reproducibility. Among the evaluated classifications, the Universal classification demonstrated predictive ability when subtypes were grouped. The IDEAL classification showed predictive power in both global and grouped analyses. In the AO/ASIF system, subtype C3 was associated with an increased risk of loss of reduction. The Frykman and Fernandez classifications and the LaFontaine criteria showed no significant predictive value. Regarding reproducibility, IDEAL and LaFontaine showed moderate agreement, while the remaining systems demonstrated poor concordance. Advanced age was an independent risk factor for instability. This study demonstrates that among the analyzed classifications, the AO/ASIF (type C3), Universal (unstable types IIB, IIC, IVB, IVC), and IDEAL systems provide prognostic value for predicting instability, with higher relative risks of loss of reduction. Reproducibility analysis showed better performance for the LaFontaine and IDEAL systems. Age emerged as an important prognostic factor, particularly in patients older than 65 years. Prognosis, Level 1b.