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

Abstract

PurposeLongitudinal cohort studies of knee OA aetiology use MRI to assess meniscal extrusion within the same knee at sequential time points. A validated method of assessment is required to ensure that extrusion is measured at the same location within the knee at each time point. Absolute perpendicular extrusion from the tibial edge can be assessed using the reference standard of segmentation of the tibia and medial meniscus. This is labour intensive and unsuitable for large cohorts. Two methods are commonly used as proxy measurements. Firstly, the apex of the medial tibial spine is used to identify a reproducible MRI coronal slice, from which extrusion is measured. Secondly, the coronal MRI slice of the knee demonstrating the greatest extrusion is used. The purpose of this study was to validate these two methods against the reference standard and to determine the most appropriate method to use in longitudinal cohort studies. We hypothesised that there is no difference in absolute meniscal extrusion measurements between methods.MethodsTwenty high-resolution knee MRI scans were obtained in asymptomatic subjects. The tibia and medial meniscus were manually segmented. A custom MATLAB program was used to determine the difference in medial meniscal extrusion of the knee using the reference standard compared to the two other methods.ResultsAssessing extrusion using the single coronal MRI slice demonstrating the greatest extrusion overestimates the true extrusion of the medial meniscus. It incorrectly places the greatest meniscal extrusion at the anterior part of the tibia. Assessing extrusion using a consistent anatomical landmark, such as the medial tibial spine, most reliably corresponds to the reference of segmentation and measurement of true perpendicular extrusion from the tibial edge. Clinicians and researchers should consider this when assessing meniscal extrusion in the knee, and how it changes over time.ConclusionThis study suggests measuring meniscal extrusion on the coronal MRI slice corresponding to the apex of the medial tibial spine as this correlates most closely with the true perpendicular extrusion measurements obtained from manually segmented models.Level of evidenceDiagnostic, Level I.

Preoperative Medial Meniscal Extrusion Is Associated With Patient-Reported Outcomes After Medial Opening Wedge High Tibial Osteotomy

“…32 The MME was measured in the midcoronal plane image where the largest area of the medial tibial spine was observed. 5,15 Patients with missing meniscal tissue on preoperative MRI scans were excluded from the analysis. The measurements were performed by drawing 2 lines as follows 7 : The first line was a vertical line intersecting the medial margins of the medial tibial plateau.…”

Preliminary diagnosis of medial meniscus posterior root tears using the Rosenberg radiographic view

“…MRI evaluation was performed in the supine position, using either an Achieva 1.5 T (Philips, Amsterdam, The Netherlands) or an EXCELART Vantage powered by Atlas 1.5 T (Toshiba Medical Systems, Otawara, Japan), with a knee coil. Measurement of MME was performed using a bony landmark method, which is considered more reproducible than a coronal slice method [22]. A coronal plane through the MTE was used to measure the horizontal distance between the most medial aspect of the tibia and the most medial aspect of the meniscus on this image (Fig.…”

Sonographic evaluation of lateral meniscal extrusion: implementation and validation

“…Different techniques for ME measurement have been described in the literature [ 5 , 37 , 38 ]. Coronal MR slices, as obtained in the present study, are oriented parallel to the posterior condylar line of the femur and represent the imaging standard for measurements of ME.…”

“…Lateral meniscal extrusion in the healthy and surgically treated (injured) knees in Group II Measurements of lateral meniscal extrusion are presented as mean ± standard deviation ME meniscal extrusion; n number of investigated knees *Statistically significant difference between the healthy and surgically treated (injured) knees (p < 0.05) ME, when menisci extrude anteriorly or posteriorly from the imaging plane, and overestimations of ME, when measurements are obtained posterior to the joint midline. For these reasons, Jones et al[38] have recently recommended obtaining radially orientated MR slices, running perpendicular to the tibial and meniscal rim, to minimize the risk of bias due to incorrect slice angulation. Since the spatial resolution of both MRI and US is excellent, deviations of results are likely due to differences in imaging planes.…”