Abstract: AIM: To observe the changes of the hip in means of injecting 2‰ noradrenaline (NA) into the hip joint cavity and study the pathogenesis of transient sy-novitis of hip. METHODS: Forty 2-3 months old dogs were divided into 10 groups,and 2‰ NA was injected into the hip joint. ^99mTC-MDP triphasic imaging was used to observe the local blood supply of femoral head, intra-articular pressure was determined, and patholoyical changes were observed to understand the natural course of the disease process. RESULTS: Injecting 2‰ noradrena-line resulted in transient contraction of blood vessels in femoral head and after 3 hours blood vessels begun to ex-pand, exudation of hip joint caused an increase of pressure in hip joint. This process continued for 2 weeks. There was no necrosis of synovium and femoral head. The whole process resembled transient synovitis of hip in the clinical manifestation. CONCLUSION: Injecting 2‰ noradrenaline results in extension and congestion of hlood vessels. An increase of pressure in hip joint causes tran-sient ischemia in femoral head. The whole process resem-hles transient synovitis of hip in the clinical manifesta-tion.Noradrenaline may play an important role in the pathogenesis of transient synovitis of hip.

Key words: noradrenaline, synovitis, hip, femoral head