Medial meniscal extrusion: a validation study comparing different methods of assessment

Area of Science:

• Orthopedics
• Radiology
• Biomedical Engineering

Background:

• Longitudinal knee osteoarthritis (OA) studies require precise MRI assessment of meniscal extrusion.
• Accurate measurement at sequential time points necessitates a validated, reproducible method.
• Current proxy methods for medial meniscal extrusion lack standardization.

Purpose of the Study:

• To validate two common proxy methods for measuring medial meniscal extrusion against a reference standard.
• To determine the most appropriate MRI assessment method for longitudinal OA cohort studies.
• To compare extrusion measurements using the medial tibial spine landmark versus the greatest extrusion slice.

Main Methods:

• Diagnostic study utilizing high-resolution knee MRI scans from 20 asymptomatic subjects.
• Manual segmentation of the tibia and medial meniscus to establish a reference standard for extrusion.
• Custom MATLAB program to compare extrusion measurements from two proxy methods against the reference standard.

Main Results:

• Measuring extrusion on the slice with the greatest apparent extrusion overestimates true medial meniscal extrusion.
• This method incorrectly localizes maximal extrusion to the anterior tibia.
• Using the medial tibial spine landmark provides the most reliable and reproducible measurement of true perpendicular extrusion.

Conclusions:

• The coronal MRI slice corresponding to the apex of the medial tibial spine is the most accurate method for measuring medial meniscal extrusion.
• This landmark-based approach closely correlates with reference standard measurements.
• Clinicians and researchers should adopt this method for consistent assessment of meniscal extrusion in longitudinal OA studies.