Objective To investigate the best pathway and safety of sacroiliac joint (SIJ) puncture.Methods The anticorrosive adult specimens were frozen after SIJ CT scan.Horizontal or coronary sectioning was done.The horizontal sectioning was done corresponding to CT scan.The structures of different sections were observed and compared with the corresponding CT scans.Results According to the horizontal sectioning,the SIJ included synovial portion and ligamentous portion.As shown by CT,only part of the space between sacrum and ilium was the synovial portion,which occupied the whole part of the lower 1/3 segment SIJ,and the posterior was not covered with bones.There are no important nerves and blood vessels passing through the route from the buttock to the posterior of SIJ.Thus,the pathway can be regarded as the best and safe one although the lumbosacral trunk and iliac blood vessels go through the anterior of SIJ in the pelvis.Conclusion The best pathway of SIJ puncture is the upper part of the lower 1/3 segment.The safety of puncture depends on not penetrating the pelvic cavity to avoid damaging the structures in pelvis.

BACKGROUND: The nomination of undifferentiated spondyloarthropathy (USpA) has provided clues for the early diagnosis of spondylitis ankylopoietica and other subsets of SpA, thereby avoiding possible wrong treatments.OBJECTIVE: To investigate the prevalence of SpA in the workers and their adult relatives aged over 16 years old from a factory in Beijing urban district, as well as the results of human major histocompatibility complex (MHC) B27 and X-ray inspection on sacroiliac joint.DESIGN: Systematic sampling investigation.SETTING: Department of Internal Medicine, Chenghai District People's Hospital of Shantou City; Rheumatism Research Institute, Medical College of Shantou University; Department of Internal Medicine, Beijing Chaoyang Hospital.PARTICIPANTS: A survey was conducted among 1982 workers and their adult relatives aged over 16 years from a factory in Beijing urban district between May and October 1999; there were 1,025 males and 957 females.They all volunteered into this study after informed of the experiment.METHODS: All examinees were surveyed door to door with the modified Chinese-International Anti-rheumatic Alliance Rheumatism Questionnaire,those with positive results were subjected to physical examination and those suspicious cases were subjected to MHC-B27 and X-ray examination.MAIN OUTCOME MEASURES: The prevalence of SpA in the workersand their adult relatives aged over 16 years from a factory in Beijing urban district, as well as the results of MHC-B27 and sacroiliac joint X-ray inspection.RESULTS: Totally 1,982 subjects were enrolled in this study and all entered the result analysis. The prevalence of spondyloarthropathy was 1.61%(32/1 982), amongst which the prevalence of ankylopoietic spondylitis,USpA, and psoriastic arthritis was 0.31% (6/1 982), 1.21% (24/1 982),and 0.10% (2/1 982), respectively. No other subsets of SpA were observed. USpA was mainly presented by inflammatory lumbago and asymmetric arthrosteitis [83% (20/24), 62% (15/24)], while rheumatoid factor was negative in all subjects. Meanwhile, MHC-B27 was proved positive in 25% (6/24) subjects with the male-to-female ratio of 1.2:1.CONCLUSION: The prevalence of SpA is 1.61% in Beijing urban area,and SpA mainly consists of ankylopoietic spondylitis and USpA.