Quantitative three-dimensional collagen orientation analysis of human meniscus posterior horn in health and osteoarthritis using micro-computed tomography

V.-P Karjalainen,I Kestilä,M.A Finnilä,E Folkesson,A Turkiewicz,P Önnerfjord,V Hughes,J Tjörnstrand,M Englund,S Saarakkala

doi:10.1016/j.joca.2021.01.009

V.-P Karjalainen, I Kestilä + Show 8 more

Open Access

PDF Available

https://doi.org/10.1016/j.joca.2021.01.009

Copy DOI

Export

Save

Cite

Abstract
Highlights/Summary
Full-Text PDF
Similar Papers

Abstract

Listen

Knee osteoarthritis (OA) is associated with meniscal degeneration that may involve disorganization of the meniscal collagen fiber network. Our aims were to quantitatively analyze the microstructural organization of human meniscus samples in 3D using micro-computed tomography (μCT), and to compare the local microstructural organization between OA and donor samples. We collected posterior horns of both medial and lateral human menisci from 10 end-stage medial compartment knee OA patients undergoing total knee replacement (medial & lateral OA) and 10 deceased donors without knee OA (medial & lateral donor). Posterior horns were dissected and fixed in formalin, dehydrated in ascending ethanol concentrations, treated with hexamethyldisilazane (HMDS), and imaged with μCT. We performed local orientation analysis of collagenous microstructure in 3D by calculating structure tensors from greyscale gradients within selected integration window to determine the polar angle for each voxel. In donor samples, meniscus bundles were aligned circumferentially around the inner border of meniscus. In medial OA menisci, the organized structure of collagen network was lost, and main orientation was shifted away from the circumferential alignment. Quantitatively, medial OA menisci had the lowest mean orientation angle compared to all groups,-24° (95%CI -31 to-18) vs medial donor and-25° (95%CI -34 to-15) vs lateral OA. HMDS-based μCT imaging enabled quantitative analysis of meniscal collagen fiber bundles and their orientations in 3D. In human medial OA menisci, the collagen disorganization was profound with overall lower orientation angles, suggesting collagenous microstructure disorganization as an important part of meniscus degradation.

Highlights

The samples were thawed in phosphate buffered saline (PBS), and the posterior horn was separated from the meniscus body with a scalpel followed by fixation in 4% saline-buffered formaldehyde for a minimum of 11 days
Collagen fiber bundles in HMDS-treated meniscal samples were successfully depicted in 3D using micro-computed tomography (mCT)
In Fig. 5(A) we show the percentage of voxels as a function of orientation angle in each sample from OA samples and in Fig. 5(B) from donor samples

Summary

Introduction

A superficial layer covers the femoral and tibial surfaces of the menisci with thin but dense randomly oriented collagen fiber network that is parallel to the surface[11,12]. In the outer border of both medial and lateral menisci, radial collagen bundles orient orthogonally and intertwine with circumferentially aligned fibers, tying the meniscus together[11,15,16]. These bundles provide additional mechanical reinforcement and prevent separation of circumferentially oriented bundles[17]

Methods

Results

Conclusion