OBJECTIVE: To test the external validity of the fracture to plafond (FTP-length of fracture/distance to plafond) ratio to rule out distal intra-articular fractures (DIA) in distal tibial shaft fractures at an independent tertiary trauma center. DESIGN: Retrospective cohort study. SETTING: Two Level 1 trauma centers. PATIENTS: Two hundred seventeen patients with a distal tibial shaft fracture in the model cohort and 146 patients in the validation cohort. INTERVENTION: Radiographic measurements to calculate FTP ratio. MAIN OUTCOME MEASUREMENTS: Calibration plots, area under receiver operating characteristic curve (AUC), and decision curve analyses to evaluate the external validity of FTP ratio to determine DIA. RESULTS: The AUC for the anteroposterior (AP) FTP ratio was 0.83 [95% confidence interval (CI) 0.78-0.88] in the model data set and 0.86 (95% CI 0.80-0.91) in the validation data set. The AUC for the lateral FTP ratio was 0.82 (95% CI 0.77-0.87) in the model data set and 0.82 (95% CI 0.75-0.88) in the validation data set. The previously established AP FTP cutoff ratio of 0.61 had a 94% negative predictive value in the model cohort and a 100% negative predictive value in the validation cohort. CONCLUSION: The FTP ratio is an effective and externally validated screening tool to rule out DIA in distal tibia shaft fractures. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.
ASJC Scopus subject areas
- Orthopedics and Sports Medicine