Quantification of Stiffness Change in Degenerated Articular Cartilage Using Optical Coherence Tomography-Based Air-Jet Indentation

Abstract

Articular cartilage is a thin complex tissue that covers the bony ends of joints. Changes in the composition and structure of articular cartilage will cause degeneration, which may further lead to osteoarthritis. Decreased stiffness is one of the earliest symptoms of cartilage degeneration and also represents the imperfect quality of repaired cartilage. An optical coherence tomography (OCT)-based air-jet indentation system was recently developed in our group to measure the mechanical properties of soft tissues. In this study, this system was applied to quantify the change of mechanical properties of articular cartilage after degeneration induced by enzymatic digestions. Forty osteochondral disks (n = 20 × 2) were prepared from bovine patellae and treated with collagenase and trypsin digestions, respectively. The apparent stiffness of the cartilage was measured by the OCT-based air-jet indentation system before and after the degeneration. The results were also compared with those from a rigid contact mechanical indentation and an ultrasound water-jet indentation. Through the air-jet indentation, it was found that the articular cartilage stiffness dropped significantly by 84% (p < 0.001) and 63% (p < 0.001) on average after collagenase and trypsin digestions, respectively. The stiffness measured by the air-jet indentation system was highly correlated (R > 0.8, p < 0.001) with that from the other two indentation methods. This study demonstrated that the OCT-based air-jet indentation can be a useful tool to quantitatively assess the mechanical properties of articular cartilage, and this encourages us to further develop a miniaturized probe suitable for arthroscopic applications.

Detecting early stage osteoarthritis by optical coherence tomography?

“…Such methods may prove especially valuable for OCT-based evaluation of femoral condyles, where AC is characterized by considerable curvature (Terukina et al, 2003 ) which makes surface position averaging challenging. Non-perpendicular optical beam angles are further known to bias the evaluation of cartilage surface degeneration by quantitative OCT (Huang et al, 2011b ). In a feasibility study, Nebelung et al performed a comprehensive OCT-based morphometric grading study on human AC representing the full spectrum of arthritic degeneration, ranging from Outerbridge 0 to 4, from macroscopically “normal” to fully eroded cartilage, respectively (Nebelung et al, 2014 ).…”

Micro‐poromechanics model of fluid‐saturated chemically active fibrous media

“…The charged proteoglycan assemblies in the hydrogel matrix are imbedded into the collagen fiber network to form a complex microstructure [73]. Furthermore, the interaction of collagen network and the hydrogel forms the main load bearing component as demonstrated by the experimental result that articular cartilage loses ∼ 84% of its stiffness when the collagen fiber network has been digested using collagenase while its loses ∼ 63% of its stiffness when proteoglycans are digested with trypsin [74]. In this case, the effective behavior of the collagen fiber-gel interaction can be expeditiously represented by the fiber element as shown by our results.…”

Measuring Human Corneal Stromal Biomechanical Properties Using Tensile Testing Combined With Optical Coherence Tomography

“…Optical coherence tomography (OCT) is a key ophthalmologic imaging technique can provide rapid, noninvasive, high-resolution in vivo imaging of corneal structures, which enables its broad diagnostic and therapeutic applications ( Ang et al, 2018 ; Spaide et al, 2018 ; Wang et al, 2019 ). In addition, OCT can assist tissue biomechanical detection when combined with an air-puff ( Huang et al, 2011 ) or shear wave elastography ( Wang and Larin, 2015 ). Among all categories of OCT devices, spectral-domain OCT (SD-OCT) has the advantages of high-speed acquisition and high axial resolution.…”