Contralateral MRI scan can be used reliably for three-dimensional meniscus sizing - Retrospective analysis of 160 healthy menisci

Abstract

Background: Meniscus allograft transplantation is a valuable surgical option for post-meniscectomy syndrome. For best results, the selected allograft should be as similar as possible to the original meniscus. Three-dimensional meniscus sizing could be a new approach to improve the accuracy of meniscus matching. The contralateral anatomy might therefore be a suitable reconstruction template. The purpose of this study was to compare the three-dimensional shape of the right and left menisci by bi-planar segmentation of magnetic resonance imaging (MRI) scans.

Methods: Three-dimensional surface models of healthy menisci were created based on 40 bilateral MRI scans. Manual segmentation was performed on the MRI data in sagittal and coronal planes. For side-to-side comparison, each left meniscus model was mirrored and then superimposed to its corresponding right meniscus model. Differences between the meniscus pairs were assessed by width, length, height and surface distances. Inter-reader reliability, as well as accuracy of bi-planar segmentation was assessed by two different readers.

Results: The meniscus pairs were not significantly different in terms of width, length and height (P = at least 0.138). Side difference of mean surface distances was 0.76 mm (±0.13 standard deviation (SD)) for medial and 0.78 mm (±0.15 SD) for lateral menisci. Inter-reader reliability was good to excellent (0.828-0.987).

Conclusion: The three-dimensional shapes of the left and right menisci are very similar. Therefore, the contralateral meniscus can be used as a template for three-dimensional meniscus allograft sizing. Three-dimensional meniscus segmentation and sizing can be performed accurately by combination of sagittal and coronal planes.

Keywords: 3D; Allograft; Knee; MRI; Meniscus; Sizing.