High Resolution Micro-Computed Tomography Reveals a Network of Collagen Channels in the Body Region of the Knee Meniscus

Abstract

The meniscus is an integral part of the human knee, preventing joint degradation by distributing load from the femoral condyles to the tibial plateau. Recent qualitative studies suggested that the meniscus is constituted by an intricate net of collagen channels inside which the fluid flows during loading. The aim of this study is to describe in detail the structure in which this fluid flows by quantifying the orientation and morphology of the collagen channels of the meniscal tissue. A 7 mm cylindrical sample, extracted vertically from the central part of a lateral porcine meniscus was freeze-dried and scanned using the highest-to-date resolution Microscopic Computed Tomography. The orientation of the collagen channels, their size and distribution was calculated. Comparisons with confocal multi-photon microscopy imaging performed on portions of fresh tissue have shown that the freeze-dried procedure adopted here ensures that the native architecture of the tissue is maintained. Sections of the probe at different heights were examined to determine differences in composition and structure along the sample from the superficial to the internal layers. Results reveal a different arrangement of the collagen channels in the superficial layers with respect to the internal layers with the internal layers showing a more ordered structure of the channels oriented at 30$$^{\circ }$$ ∘ with respect to the vertical, a porosity of 66.28% and the mean size of the channels of 22.14 $$\mu {\text {m}}$$ μ m .

Comparison of temporomandibular joint disc, meniscus, and intervertebral disc in fundamental characteristics and tissue engineering

“…23 Additionally, in the same layer of AF, collagen fibers are highly aligned, approximately in a direction at 30-45 angle with the circumferential line as the axis, with fibers in the adjacent two layers going opposite and crisscrossing each other 24 (Figure 3A). Differently, in superficial layer of meniscus, these fibers are thin, oriented randomly 26 (Figure 3B).…”

The Human Meniscus Behaves as a Functionally Graded Fractional Porous Medium under Confined Compression Conditions

“…Currently, the clinical outcomes of these implants are not ideal [5] due to the fact that they do not mimic the structure-property relationships of the tissue as these are still not well understood [6]. Among many biologic tissues, the meniscal tissue is composed of porous solid matrices-mainly collagen-with fluid filling the pores [7][8][9][10]. The overall mechanical behaviour of this type of tissues depends not only on the solid matrix deformation, but also on the movement of the fluid in and out of the collagen channels [7,8] during the deformation.…”

“…Among many biologic tissues, the meniscal tissue is composed of porous solid matrices-mainly collagen-with fluid filling the pores [7][8][9][10]. The overall mechanical behaviour of this type of tissues depends not only on the solid matrix deformation, but also on the movement of the fluid in and out of the collagen channels [7,8] during the deformation.…”

“…The investigation of the material properties, coupled with the quantification of architectural parameters, such as the porosity and channel interconnectivity, will enable the design of artificial cellular structure, which can resemble the native behaviour of the tissue (see, for instance, [11]). More in depth, advanced microscopy investigations highlighted that collagen bundles form the wall of channels, which can be observed both at the macroscale and at the microscale [7,10]. Fluid is able to flow inside these channels in response to physiological loading.…”

A unified modelling and simulation for coupled anomalous transport in porous media and its finite element implementation

“…This paper introduces a unified formalism for coupled anomalous diffusion processes in porous media as well as a simple open-source implementation in FE commercial code. It was noticed that in soft tissue hydrated with water such as articular cartilage [1] and meniscus [2][3][4][5][6] the interstitial water pressurizes when the tissue is loaded. The fluid pressurization has been hypothesized to be a major factor in the load-support mechanism and in the response to friction of these types of tissues [1].…”