Development of a novel micro-CT based scoring system for the assessment of joint structure in a rat model of
Takuya Takata1, Tatsunori Ikemoto1, Young-Chang Arai2
1Department of Orthopedics, School of Medicine, Aichi Medical University, Nagakute, Japan.
Background:
Osteoarthritis (OA) is a degenerative joint disease involving cartilage loss and inflammation. Traditional histological evaluation is limited. Micro-computed tomography (micro-CT) offers non-invasive three-dimensional (3D) joint visualization but lacks detailed cartilage assessment. This study developed and evaluated a novel micro-CT-based scoring system for joint structure in a rat model of mono-iodoacetate (MIA)-induced OA.
Methods:
OA was induced in the right knees of 24 Wistar male rats using varying MIA concentrations (0.2, 0.5, 1, 3 mg). After 28 days, knee joints were scanned using micro-CT and segmented into 10 compartments. Degenerative changes in each compartment were scored (0-4), and a total joint score was calculated. Histological evaluation using a modified Mankin score was performed on sagittal sections of the patellar groove. Interobserver reliability and correlations between micro-CT joint scores and Mankin scores were analyzed statistically.
Results:
The micro-CT 3D imaging scoring system demonstrated excellent interobserver reliability [interclass correlation coefficient (ICC) >0.75 for most compartments]. Micro-CT joint scores revealed statistically significant differences in joint degeneration between the highest MIA dose group (3 mg) and the lower dose groups (0.2 and 0.5 mg). Notably, micro-CT could differentiate between the 0.2 mg and 1mg groups, which was not fully reflected in histological scores. A strong correlation was found between the total micro-CT joint score and the modified Mankin score (ρ=0.8, P<0.001).
Conclusions:
The novel micro-CT-based 3D imaging scoring system provides a reliable method for quantifying gross degenerative changes in rat knee joints in the MIA-induced OA model. While it does not directly assess cartilage, its correlation with histological findings suggests its utility as a complementary tool for evaluating overall joint degeneration.
