Objective: In view of the extensive bone damage in rheumatoid arthritis

we used a commonly utilized animal model to detect behavioral changes in pain-related and the bone damage during the early disease

and to explore the correlation between bone damage and pain-related behavioral changes. Methods: Arthritis were induced in Sprague-Dawley （SD） male rats by injecting complete Freund’s adjuvant （CFA） into the tails. Pain-related behavior changes were studied using the Hargreaves

VonFrey

and acetone tests on the 0

7

14

day and 28 day after CFA injection. The rats were sacrificed according the same schedule. The bone damage of the right proximal tibia was studied by microCT scan and bone histological slices. Results: Animals developed soft tissue inflammation and polyarthritis on 7 days after CFA injection

and arthritic score proved obvious arthritis were established within the study period. Mechanical hyperalgesia and cold allodynia were present in the affected hind paw from the 7 day through the 28 day

but the heat hyperalgesia and the mechanical allodynia lasted a short time after CFA injection. Trabecular bone number （Tb.N）

Tissue Mineral Content （TMC） and Bone Volume to Tissue Volume （BV/TV） in the proximal tibia by microCT scan were also reduced after induction

especial 14 days after CFA injection. The bone histological slices showed the trabecular bone and proteoglycan diminished

the bone damage severity scores became more severely on the 7 day after CFA injection. Using analysis of covariance

these changes had statistical significance compared with baseline. By linear regression analysis demonstrated mechanical hyperalgesia and cold allodynia correlated well with arthritic score

bone damage parameters and bone damage severity scores. Conclusion: Adjuvant-induced arthritis （AA） were observed after CFA injection and lasted within the later experimental period. Pain-related behavioral changes were observed in the early time of AA. Bone damage was also occurred with arthritis development. Pain-related behavioral change correlated well with arthritic score and bone damage parameters.