Transforming growth factor-pi and fibroblast growth factor-2 play very important roles in fibroblast proliferation and collagen expression. These processes lead to the formation of joint adhesions through the SMAD and MAPK pathways. in which extracellular signal-regulated kinase (ERK)2 is considered to be Crucial Based on these theories, we examined the effects of a lentivirus-mediated small interfering RNA (siRNA) targeting ERK2 on the suppression of joint adhesion formation in vivo The effects were assessed in vivo from different aspects including the adhesion score, histology and joint contracture angle We found that the adhesions in the ERK2 siRNA group became soft and weak, and were easily stretched Accordingly. the flexion contracture angles in the ERK2 siRNA group were also reduced (P < 0 05 compared with the control group). The animals appeared healthy, with no signs of impaired wound healing. In conclusion. local delivery of a lentivirus-mediated siRNA targeting ERK2 call ameliorate joint adhesion formation effectively and safely (C) 2009 Elsevier Inc All rights reserved