Anatomy And Radiation Anatomy Study On The Sacroiliac Joint

1.Objective:1.1 To provide anatomical morphological basis for clinical diagnosis sacroiliac joint diseases and Lumbosacral-related diseases after observing the anatomy of the sacrum common variations.1.2 To study and measure the morphological characters of accessory auricular surface of sacrum and to probe its implications.1.3 To study X-ray of normal and ankylosing spondylitis patients with sacroiliac joint and provide the diagnosis basis for sacroiliac joint diseases.1.4 To study the sacroiliac joint and auricular surface(accessory auricular surface)of dry pelvis cases in the AP view and inclined view X-ray to provide the correct x-ray anatomical basis.2.Method2.1 To observe anatomic features of sacrums with cell-extracellar sacral vertebra, accessory auricular surface,sacral askew in dry sacrums in 96 cases.2.2 According to the gender of the observed samples,the incidence rate, location,horizontal and vertical radius vector and anatomic features of sacrums with accessory auricular surface were observed and measured in dry sacrums in 96 cases.2.3 43 cases of X-ray AP view in pelvis were chose,2leases of male(16 cases of ankylosing spondylitis,5 cases of normal)and 22 cases of female(14 cases of ankylosing spondylitis,8 cases of normal).To observe the change of sacroiliac joint gap(such as anterior and posterior gap and it's position)and sacroiliac joint length.2.4 The bilateral auricular surface and accessory auricular surface in sacrum and ilium were connected and fixed after besmeared barium in 3 pelvis cases.Auricular surface and accessory auricular surface projection and morphological characters were observed in X-ray AP view and inclined view photographs respectively.After washing the barium,the changes of auricular surface and the edge of accessory auricular surface with different postures X-ray were observed,with the edge of auricular surface and accessory auricular surface fixed with fine wire.Then changes in anterior and posterior gap were observed with removed the fine wire.3.Result3.1 The incidence of sacrum variation was high in sacral vertebra cracked and sacral askew(25%and 20.59%respectively in male cases 21.42%and 25% respectively in female cases).The incidence of lumbarization of sacral vertebra was less than 5%in both sexes cases.17 cases of transitional vertebra,including 14 cases of sacralization and 3 cases of lumbarization of sacral vertebra;23 cases of sacral vertebra cracked in whichⅠ°,Ⅱ°,Ⅲ°is 13 cases,6 cases and 4 cases respectively.21 cases of sacrum skewed;14 cases of accessory auricular surface.3.2 For all of the samples,14 samples(14.58%)had accessory auricular surfaces,of which 13 were male,one female.The accessory auricular surfaces were bilateral in most specimens,at the posteroinferior of sacroiliac joint and formed an angle with auricular surface.There were many variations in sacrums with aeeessory auricular surfaces.3.3 The sacroiliac joint was shown as bilateral single gap or bilateral double gap the majority,the proportion more than 80%in both sexes,the bilateral double gap was common(52.38%of male and 40.91%of female).With the bilateral gap in the sacroiliac joints,the rate of anterior gap was 60.00%;the rate of posterior gap was 55.00%and most showed in inferior.It was few in the upper and central.The sacroiliac joint length was most in the same horizontal plane with S₃(61.90%of male and 68.18%of female),followed by S₄,S₂ was the least.3.4 The pelvis inclined view of X-ray clearly showed the boundary and scope of auricular surface and accessory auricular surface and could be observed clearly ipsilateral upper of sacroiliac joint gap.4.Conclusion4.1 The anatomic variations were very common in sacrum and should be considered when diagnose the related diseases to avoid misdiagnosis.4.2 The incidence of accessory auricular surface was related to loads of body and gender of subject.In diagnosis and imaging examinations of sacroiliac joint diseases, factor of accessory auricular surface should be taken into account.4.3 The presence of the bony convex structure and orientation of auricular surface and auricular surface made the findings of SI joint on X-ray more complex., pathological changes in posterior gap should be not ignored when double gap display.4.4 The correct observed method had great meaning in diagnose disease of the sacroiliac joint early.