Quantifying birefringence in the bovine model of early osteoarthritis using polarisation-sensitive optical coherence tomography and mechanical indentation

Abstract

Recent studies have shown potential for using polarisation sensitive optical coherence tomography (PS-OCT) to study cartilage morphology, and to be potentially used as an in vivo, non-invasive tool for detecting osteoarthritic changes. However, there has been relatively limited ability of this method to quantify the subtle changes that occur in the early stages of cartilage degeneration. An established mechanical indenting technique that has previously been used to examine the microstructural response of articular cartilage was employed to fix the bovine samples in an indented state. The samples were subject to creep loading with a constant compressive stress of 4.5 MPa and, when imaged using PS-OCT, enabled birefringent banding patterns to be observed. The magnitude of the birefringence was quantified using the birefringence coefficient (BRC) and statistical analysis revealed that PS-OCT is able to detect and quantify significant changes between healthy and early osteoarthritic cartilage (p < 0.001). This presents a novel utilization of PS-OCT for future development as an in vivo assessment tool.

Detection of subtle cartilage and bone tissue degeneration in the equine joint using polarisation-sensitive optical coherence tomography

“…Alone, the framework provides little extra value in the wider diagnostic scope. Similarly, extracting birefringence as a measure of matrix integrity has been performed in multiple studies with various success 23,26 . Each quantitative metric effectively provides information on a single part of the complex osteoarthritis puzzle.…”

“…Studying OA with (PS)-OCT has been done previously by several groups, most with the ultimate objective to characterise and quantify human cartilage degeneration [14][15][16][17][18][19][20][21][22][23][24][25][26] . While these studies present promising results, they largely focus on differentiating cartilage based on conventional OA grading schemes.…”

Impact-Induced Cartilage Damage Assessed using Polarisation-Sensitive Optical Coherence Tomography

“…[32][33][34] PS-OCT based metrics revolve around quantifying the strength of the birefringence -an indirect measure of collagen matrix arrangement. 34,35 Optical axis orientation can also be extracted from polarisation-sensitive measurements which has recently allowed the full three dimensional reconstruction of collagen fiber orientation using a tractographic extension of PS-OCT. 36,37 Currently, de Bont et al 38 are the only group to have parameterised impact-induced cartilage degeneration using OCT and while they concluded OCT can reliably detect degenerative features, no polarisation metrics have been evaluated nor has the optical response of degenerate cartilage been evaluated following impact. It is also important to note that the previous OCT study was carried out only on tissue obtained from OA patients, which leaves open the question of how healthy and structurally intact cartilage may respond.…”

Simultaneous tractography and elastography imaging of the zone-specific structural and mechanical responses in articular cartilage under compressive loading

“…Due to the highly organized collagen matrix, cartilage samples show significant optical birefringence that can be quantified using optical polarization based methods such as PLM or polarization-sensitive optical coherence tomography (PSOCT) [22][23][24]. Recently, a PSOCT based tractography imaging method has shown potential for high-resolution visualization of detailed fiber organization in tissue [25][26][27][28].…”