Langenskiöld classification of tibia vara: a multicenter study on interrater reliability

Area of Science:

• Orthopedics
• Radiology
• Medical Imaging

Background:

• The Langenskiöld classification, established in 1952 for tibia vara, is widely used in orthopedic research.
• Previous studies have explored the reliability of this classification system.
• The potential for improved reliability using subspecialist expertise and Magnetic Resonance Imaging (MRI) remains an area of investigation.

Purpose of the Study:

• To evaluate the inter-rater reliability of the Langenskiöld classification for tibia vara.
• To compare the reliability of the classification using standard radiographs versus MRI.
• To assess if expert subspecialists and advanced imaging enhance classification consistency.

Main Methods:

• A cross-sectional, multicenter study involving 12 expert raters (pediatric orthopedic surgeons and musculoskeletal radiologists) from France and Iran.
• Independent classification of tibia vara cases using both conventional radiographs and MRI (T1, T2, fat saturation sequences).
• Statistical analysis using weighted kappa and percentage agreement, including analysis of a proposed regrouping of stages.

Main Results:

• Mean weighted kappa for radiographs was 0.47 and for MRIs was 0.45, indicating moderate agreement.
• Mean percent total agreement was 46.6% for radiographs and 40.8% for MRIs.
• A proposed regrouping of stages showed improved kappa statistics (0.53 for radiographs, 0.46 for MRIs), particularly for stages 2-5.

Conclusions:

• The Langenskiöld classification demonstrates, at best, moderate inter-rater reliability among expert orthopedic specialists.
• Variability in classification is most pronounced in stages 2, 3, and 4, potentially influencing treatment decisions.
• Utilizing MRI did not significantly enhance the reliability of the Langenskiöld classification, although regrouping the stages improved consistency.