Recent experimental researches supports the hypothesis that mechanical stimuli play a role in regulating specialized molecules expression in articular cartilage in vitro and in vivo. Therefore we are studying bioreactor to provide a stimulus of mimicked real knee environment. Our bioreactor system consists of a joint motion stimulation device and culture chamber. We fabricated a stimulation system similar to movement of the CPM(Continuous Passive Motion) device for human joint motion. This system is composed of a linear stage, ball spline and links. Also we fabricated a culture system for media and circulation and mimicked knee environment. However, Previous culture system has some problems that media leakage and interference of joint model. In this study, we improved a new-chamber system for non-interference of joint model and medium sealing. Then, this system could be used to investigate the effect of dynamic culture.

Osteoarthritis is a degenerative joint disease and is led to physical disability. Yet the development of effective disease-modifying treatments has lagged. In this study, I examined the effect of physical therapeutic intervention through microcurrent stimulation and attempt to find which degree of intensity, either 25 or 500 with a regular 5 pps pulse, is more effective in the osteoarthritis. Osteoarthritis was induced with a mixture of 2% carrageenan and 2% kaolin in 26 male Sprague-Dawley rats. The mixture (0.1 ) was injected into the intra-articular capsule of knee joint once a week for three weeks. Five animals did not show degenerative changes by radiological findings and excluded in the following experiment. Osteoarthritic animals were randomly divided into 3 groups (, , =7/each): untreated, treated with 25 , treated with 500 . All experimental groups received microcurrent stimulation for four weeks (15 min/day, 5 days/week). The ethological inspection of foot print analysis on the walking corridor was accomplished every week. Histological preparations and immunohistochemical staining with insulin-like growth factor-1 were also done in the articular cartilages. All of these parameters were compared with those of osteoarthritic control group (n=7). The ethological inspection of foot print analysis revealed that changes of walking track (paw width) and stride length was significantly increased in both experimental groups. The better results were observed in experimental group treated with 25 intensity without significance than group treated with 500 . Histological preparations disclosed that routine hyaline cartilage of articular surface were altered to fibrous cartilage in untreated group and experimental group treated with 500 intensity. But a little changes were seen in experimental group treated with 25 intensity. Immunolocalization of insulin-like growth factor-1 was simultaneously decreased according to the duration of osteoarthritis, and did not show significant difference among the groups. In this study discovered that the microcurrent stimulation, especially 25 intensity, had a positive effect by the ethological inspection, histological and immunohistochemical stainings. These results suggest that microcurrent stimulation with low-intensity might be effective in the promotion of healing process for the osteoarthritis.