Abstract: Abstract: Objective To investigate the therapeutic effects of mechanical loading on early and late osteoarthritis (OA) of model mice. Methods Thirty-six 8-week-old female C57BL/6 mice, weighing about 20 g, were divided into the normal control (Control) group, OA group, and OA + loading (OAL) group by a random number table method. Each group was subdivided into 2-week and 8-week sub-groups (n=6). H&E and Safranin O/fast green staining were used to evaluate the therapeutic effects of mechanical loading on cartilage, synovium and osteophyte in early and late OA mice. Results Compared with the Control group, the thickness of hyaline cartilage (HC) and the thickness of all articular cartilage (TAC) were thinner in OA mice, and the OARSI score, synovial score and osteophyte score were significantly increased (all P＜ 0.05). After mechanical loading, the thickness of HC and TAC were increased in OAL group, and OARSI score, synovial score and osteophyte score were decreased (all P＜0.05). The relative data suggested that pathological changes were more severe in mice with late OA compared with mice of early OA, and the therapeutic effect of mechanical loading was better for the late OA. Correlation analysis showed that the early cartilage degradation of OA may be related to the synovial inflammation, and the late stage of OA may be related to the osteophyte formation. Conclusion Mechanical loading can improve the pathological changes of osteoarthritis mice, indicating that mechanical loading can be used as a new type of clinical treatment for osteoarthritis

Key words: osteoarthritis, cartilage, articular, synovitis, osteophyte, mechanical loading