Imaging Techniques for Osteoarthritis Assessment

Knee joint images were captured by X-ray (MX-20, Faxitron X-ray, Corp., Lincolnshire, IL, United States) and SkyScan 1276 Micro-CT (Bruker, Kontich, Belgium) and NRecon version 1.6 software (Bruker) and Ingenia3.0 T MRI system (Philips, United States). The rats were anesthetized by intraperitoneal injection of pentobarbital sodium (40 mg/kg) and fixed in supine position. The bilateral ankles were fixed on the tray with adhesive tape. The lens was focused at an appropriate focal length on the knee joint of the rat and the exposure time was set to apropriate minutes to ensure a clear image. The extent of osteoarthritis was assessed by imaging findings, including joint space narrowing and articular surface calcification, as well as articular cartilage damage, according to the imaging scoring system used in previous literature with macroscopic score which was based on surface roughness and erosin. Using imaging techniques, we quantified the tibial plateau or femoral condyle surface by calculating the ratio of the lesion area to the total surface area. Both the tibial and femoral joints were evaluated based on a maximum score of 10 (Gerwin et al., 2010 (link); Kohn et al., 2016 (link); Lin et al., 2021 (link)). The scoring was performed by two experienced observers who were blinded to the study groups.