Objective:To study on relationship of inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) content in the injured local soft tissue with injured degrees of the soft tissue in the third lumbar vertebrae (L3) transverse process syndrome model rat and to observe the effect of needle-knife therapy.Methods:One hundred and sixty male SD rats were randomly divided into normal group,model group,aminoguanidine (AG) group,needle-knife group,40 rats in each group.The L3 transverse process syndrome rat model was established,and after treatment of needle-knife and AG,iNOS activities and NO contents and histomorpholocal changes in the soft tissues around L3 transverse process on 1,3,7 and 14 days were observed in the groups.Results:Compared with the normal group,iNOS activity and NO content in the model group were significantly increased (P<0.01);Compared with the model group,iNOS activities and NO contents were significantly decreased in both the needle-knife group and the AG group (both P<0.01);And both iNOS activities and NO contents were identical with both local inflammation response and injured degrees of the injured tissue in the groups.Conclusion:Needle-knife therapy can significantly inhibit generation of NO,alleviate inflammatory response and injured degree of the injured soft tissue,improve microcirculation,prevent formation of pathological scar tissue,and promote repair of the chronic soft tissue injury.