Comparison of Histologic Assessment Methods in Osteoarthritic Knee Research

• Dylan McQuiston, Medical Diagnostics, University of Delaware

• X. Lucas Lu, Mechanical Engineering, University of Delaware

Knee osteoarthritis (OA), characterized by degeneration of multiple joint tissues – including articular cartilage breakdown and changes in periarticular structures – remains a significant clinical challenge. Several semi-quantitative histological grading systems have been developed to assess the severity of OA in both clinical and animal studies. These systems are essential for the objective evaluation and comparison of pathological changes in cartilage and periarticular structures in OA. Selecting a reproducible and reliable histologic assessment method is critical in OA research, particularly when assessing the efficacy of therapeutic interventions aimed at preventing or slowing disease progression. In this project, we aim to compare three histologic assessment methods using histological images of human articular cartilage and rat knee joints, to determine which assessment, or combinations of assessments, is most appropriate for our ongoing in vitro and in vivo studies of OA treatments. Previously collected human cartilage explants and rat knee joint samples were processed and embedded in paraffin wax.  5 μm tissue sections were obtained using a microtome with a tape transfer technique. Safranin-O/Fast Green staining was used to label and analyze articular cartilage and periarticular structures. The OARSI histopathological grading and staging system, whole-joint grading system, and ImageJ-assisted quantitative measurement were performed and compared in this project. The comparison of these three histological assessment methods in this study will provide valuable insights for selecting the most appropriate method for our ongoing in vitro and in vivo OA studies to evaluate potential OA treatments.