Objective:

To assess osteoarthritis in rat models at an early stage (7 days after induction).

Materials and methods:

This is a retrospective study comparing results from previous experiments. The models compared were: a) anterior cruciate ligament transection model (CLX), and an adjuvant-induced arthritis model in two varieties b) sub-plantar (ASP), and c) intra-articular (AIA). Seven days after osteoarthritis (OA) induction, an analysis was made of the clinical, histological, radiological, and serological inflammatory markers (IL-1[3, IL-4, IL-6, TNF-a, MMP-2, and MMP-9).

Results:

The AIA model produced significant differences in several parameters, when compared to the control group. However, the levels of IL-1 were higher in all OA models than in the baseline group, being more pronounced in the CXL and AIA groups (P < .001). Surprisingly, the lowest value for IL-4 was observed in the AIA group (P < .001 versus baseline group). Furthermore, the most elevated values of MMP-2 were observed in the ASP model.

Conclusions:

Although arthritis rat models are used and compared interchangeably as if they were the same, it is shown in this work that at an early stage the models behave quite different in most of the studied variables.

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