Shear wave ultrasound elastography for estimating cartilage stiffness: implications for early detection of osteoarthritis

Abstract

Current osteoarthritis (OA) diagnosis relies on radiographic abnormalities found in later stages of the disease, posing a challenge to the treatment efficacy. Therefore, earlier detection of OA is essential for improving therapeutic outcomes. The aim of this study was to investigate the feasibility of shear wave ultrasound elastography (SWUE) to detect changes in cartilage mechanical properties under OA conditions ex-vivo. Bovine osteochondral units were harvested from femoral condyles and subjected to either trypsin degradation, cartilage surface roughness defect using varying degrees of sandpaper, or subchondral bone degeneration using formic acid (FA) injection. Shear waves were generated using a mechanical shaker, while a high-frequency ultrasound system operating at 18 MHz was employed to detect wave propagation along the samples. The elasticity of cartilage was estimated by the shear wave speed (SWS) through the auto-correlation method. Our results show that the estimated SWS of cartilage after 24, 48, and 72 hours of trypsin incubation significantly decreased by 37%, 43%, and 59%, respectively, compared to the control group. Surface roughness treatment using 150-grit sandpaper significantly decreased the SWS by 35% compared to the control. Samples treated with 7% FA showed a significant increase in SWS by 62%, 89%, and 53% compared to control, 1% FA, and 3% FA, respectively. Our findings demonstrate the feasibility of SWUE to differentiate the elastic properties of cartilage under different OA conditions. This study presents the potential of a noninvasive, nonionizing tool for early detection of OA, representing a significant step toward its clinical implementation.Graphical