Pediatric Femoral Shaft Fracture Classification: An Intraobserver and Interobserver Reliability Study

Abstract

Purpose: Fracture stability is important in choosing the optimal treatment for pediatric femoral fractures, although there is no consensus for characterizing a fracture as “stable” or “unstable.” The authors sought to measure interobserver and intraobserver reliability in classifying femoral fracture stability and examined the relationship between fracture ratio and perceived fracture stability and morphology. Methods: Fracture ratios were calculated from anteroposterior and lateral radiographs from 65 children aged 5 to 12 years, who were treated for femoral shaft fractures at a level 1 pediatric trauma center. Deidentified radiographs were placed into a PowerPoint presentation in random order and were shown to six fellowship-trained pediatric orthopaedic surgeons at two time points, 4 months apart. Raters classified stability as “stable/unstable” and morphology as “spiral/oblique/transverse.” Cohen and Fleiss kappa (k) values were calculated to determine intraobserver and interobserver reliability. Generalized linear modeling was used to compare FR to rater fracture stability and morphology. Results: The mean k for fracture stability for all raters was 0.68 (strong intraobserver agreement). The k for fracture stability during Round 1 was 0.53 (67.7% interobserver agreement, moderate). The k for fracture stability during Round 2 was 0.68 (75.4% interobserver agreement, strong). The mean k for fracture morphology for all raters was 0.79 (strong intraobserver agreement). The k for fracture morphology during Round 1 was 0.38 (15.4% agreement, fair). The k for fracture morphology during Round 2 was 0.46 (24.6% agreement, moderate). The average anteroposterior ratio in stable fractures was 1.32 compared with 1.78 in unstable fractures (P < 0.001). The average lateral ratio in stable fractures was 1.34 compared with 2.10 in unstable fractures (P < 0.001). Average anteroposterior and lateral ratios were highest in spiral fractures and lowest in transverse fractures (P < 0.003). Conclusions: Raters demonstrated strong intraobserver and interobserver agreement in classifying radiographic femoral fracture stability. Anteroposterior and lateral fracture ratios were significantly higher in unstable fractures.