Articular cartilage optical properties in the near-infrared (NIR) spectral range vary with depth and tissue integrity.

Bilour Khan,Dmitry Semenov,Isaac O Afara,Markku Hauta-Kasari,Juha Töyräs,Ervin Nippolainen,Rubina Shaikh,Iman Kafian-Attari

doi:10.1364/boe.430053

Bilour Khan, Dmitry Semenov + Show 6 more

Open Access

https://doi.org/10.1364/boe.430053

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Abstract

Optical properties of biological tissues in the NIR spectral range have demonstrated significant potential for in vivo diagnostic applications and are critical parameters for modelling light interaction in biological tissues. This study aims to investigate the optical properties of articular cartilage as a function of tissue depth and integrity. The results suggest consistent wavelength-dependent variation in optical properties between cartilage depth-wise zones, as well as between healthy and degenerated tissue. Also, statistically significant differences (p<0.05) in both optical properties were observed between the different cartilage depth-wise zones and as a result of tissue degeneration. When taken into account, the outcome of this study could enable accurate modelling of light interaction in cartilage matrix and could provide useful diagnostic information on cartilage integrity.

Highlights

Articular cartilage is a specialized connective tissue covering the ends of bones in diarthrodial joints, such as the knee, hip, and shoulder
As the orientation of collagen fibers varies with depth from the articular surface to the subchondral bone, the structure of cartilage can be categorized into three distinct layers, namely, superficial zone (SZ) middle zone (MZ), and deep zone (DZ) [5]
This zone provides the highest resistance to compressive forces and has collagen fibers oriented perpendicular to the cartilage-bone interface

Summary

Introduction

Articular cartilage is a specialized connective tissue covering the ends of bones in diarthrodial joints, such as the knee, hip, and shoulder. Collagen fibers, being a major ECM component, are distributed with depth wise architecture with parallel orientation to the articular surface in SZ, random orientation in MZ and perpendicular orientation to the articular surface in DZ [2]. As the orientation of collagen fibers varies with depth from the articular surface to the subchondral bone, the structure of cartilage can be categorized into three distinct layers, namely, superficial zone (SZ) middle zone (MZ), and deep zone (DZ) [5]. SZ comprises approximately 0–10% of cartilage thickness [6] and collagen fibers in this zone are aligned parallel to the tissue surface. The DZ covers about 70–90% of the cartilage matrix [6] and interfaces with the calcified cartilage This zone provides the highest resistance to compressive forces and has collagen fibers oriented perpendicular to the cartilage-bone interface

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