Excellent Intra- and Interobserver Reliability of the D.H. Dejour Version 2 Classification for Trochlear Dysplasia...

Area of Science:

• Orthopedic Surgery
• Radiology
• Biomedical Engineering

Background:

• The D.H. Dejour classification (Version 2 [V2]) is an update to the radiographic classification of trochlear dysplasia, incorporating computed tomography (CT) scans.
• Magnetic resonance imaging (MRI) has become the preferred imaging modality for evaluating trochlear dysplasia.

Purpose of the Study:

• To assess the reliability of the Dejour V2 classification using a combination of radiographs and MRI, replacing CT scans.
• To explore inter-assessor variability in trochlear dysplasia assessment to identify classification limitations.

Main Methods:

• A retrospective comparative study analyzed 200 patients (123 with recurrent patellar dislocation, 77 controls) with available knee MRI and lateral radiographs.
• Two orthopedic surgeons independently classified trochlear dysplasia using the Dejour V2 system, initially with radiographs and confirmed with MRI.
• Intra- and interrater reliability were calculated using kappa coefficients.

Main Results:

• In controls, 13% had type A trochlear dysplasia; in the objective patellar instability (OPI) group, 97% had trochlear dysplasia.
• Intrarater reliability was substantial (0.77) and interrater reliability was substantial (0.75) for the full classification.
• Simplifying to two grades (low vs. high) based on a supratrochlear spur significantly improved reliability (0.95 intra, 0.93 inter) and diagnostic accuracy (97.8% sensitivity, 96.4% specificity for high-grade).

Conclusions:

• The Dejour V2 classification using radiographs and MRI shows moderate sensitivity for low-grade trochlear dysplasia when using four types.
• Simplifying the Dejour V2 classification to a two-grade system (low vs. high) based on the supratrochlear spur enhances diagnostic reliability and accuracy for trochlear dysplasia.