| Objective1.1Through the anatomical observation of sacroiliac joint ligaments, to provide the anatomical basis for the mechanism of massage treatment of sacroiliac joint subluxation.1.2To observe the influence of the stress,strain and displacement when the normal sacroiliac joint is exerted load simulating oblique-pulling manipulation and further discuss scientific if the subluxation of sacroiliac joint is exist as an illness, the stress, strain and displacement distribution are analyzed when a three-dimensional finite element model of normal pelvis exerted by oblique-pulling manipulation.1.3To provide the accurate radiological anatomical evidence for clinical survey of sacroiliac joint (SI), the characteristic of the SJ is researched with the plain film radiography, including the anteroposterior and oblique radiography.1.4To explore the radiological types of the sacroiliac joint on the anteroposterior radiography of the pelvis, this may guide the clinicians to know more about the radiology of the sacroiliac joint.Method2.1(1) Five normal adult pelvis specimens, including a fresh female pelvic specimens, four embalmed adult pelvis specimens and two each for men and women). Observing the ligaments’ starting and ending points and their anatomical characteristic.(2) Cutting the sacroiliac ligaments according some order, observing the changes of the sacroiliac joint’s activity after each sacroiliac ligaments were cut.(3)When cut off all the sacroiliac ligaments, open the sacroiliac joint, observing the characteristics of the internal structure of the sacroiliac joint.(4) Observing the anatomical features of the sacroiliac space and the interosseous sacroiliac ligament in the pelvic horizontal slice.(5) Observing the anatomical features of the sacroiliac space and interosseous sacroiliac ligament in the pelvic horizontal slice.2.2A three-dimensional reconstruction and a finite element model were made using software of Mimics, Freeform and ANSYS. Lateral position is simulated on the three-dimensional finite element model of normal pelvis and it exerted loads horizontal forth and back, then the stress, strain and displacement distribution are calculated.2.3Research targeted on2dry pelvic specimens, one female and two male. Filming the anterposterior and oblique radiography of the pelvis after Coating barium evenly on the both of them and folding with tape and fastening. Observe the projective changes and morphological characters of SI as well as its auricular surface in the anteroposterior and oblique radiography.2.4950cases (male and female account for half respectively) of normal sacroiliac joints were observed on the anteroposterior radiography of the pelvis and then the radiological types of the sacroiliac joint were classified according to the number of the sacroiliac spaces and the characteristics of their shape.Result3.1(1) The iliolumbar ligament is thick and tough, starting at the fifth lumbar transverse process. It is divided into two branches, one of the branch radiate into the latter part of the iliac crest and the other radiate obliquely to the surface of the anterior sacroiliac ligament.The width of the iliolumbar ligament in the starting position(A1B1)---man is2.04±0.06cm, and female is1.98±0.05cm.And the distance between the midpoint of A1B1and the latter part of the iliac crest (C1D1)---man is5.93±0.07cm, and female is5.87±0.06cm.And both A1B1and C1D1haven’t statistical difference between man and female.(2) The anterior sacroiliac ligament is wide and thin, covering in the front of the sacroiliac joint, and connecting with the lateral margin of the sacrum pelvis and the front of the iliac auricular surface. The width of the ligament in the middle (D2E2)---man is3.09±0.06cm, and female is3.06±0.06cm.The distance between the peak of the sacroiliac space which is covered by the anterior sacroiliac ligament to the rear-end of the actuate line (F2G2)---man is5.36±0.07cm, and female is5.38±0.06cm.And both D2E2and F2G2haven’t statistical difference between man and female, too.(3) Posterior sacroiliac ligament is divided into short and long posterior sacroiliac ligament, the short posterior sacroiliac is start at the iliac tuberoses, radiating obliquely and stop at the lateral of the sacrum and the sacral joint crest. The long posterior sacroiliac ligament is cover at the surface of the short posterior sacroiliac, and start at the spinal iliac posterior superior and the2nd to4th sacral facet. It connected inwardly with the lumbodorsal fascia, and connected outwardly with the sacrotuberous ligament. The distance between spinal iliac posterior inferior and rock bottom of the lateral crest of the sacrum in the short posterior sacroiliac (A3B3)---man is3.07±0.04cm, and female is3.01±0.03cm;the distance between spinal iliac posterior superior and the4th sacral facet (C3D3)---man is6.31±0.08cm, and female is6.17±0.04cm.And both A3B3and C3D3have statistical difference between man and female;(4) The sacrotuberous ligament is located in posterior pelvic, and it is start at the iliac wing trailing edge、the sacral and coccygeal lateral margin, the fiber bundle concentrating obliquely downward, and then attached to the medial margin of ischial tuberoses. The distance between the highest iliac wing trailing edge and the lowest of the coccyx lateral margin (A4B4)---man is9.13±0.04cm,and female is9.06±0.03cm;The distance between the highest iliac wing trailing edge and ischial tuberosity (A4C4) man is6.76±0.04cm, and female is6.62±0.04cm;The distance between the lowest of the coccyx lateral margin and ischial tuberosity (B4C4)---man is6.76±0.04cm, and female is6.62±0.04cm;andA4B4、A4C4and B4C4have statistical difference between man and female;(5) Sacral ligament is in front of the sacral ligament nodules, starting at the side edge of the sacral, triangular outer oblique fibers concentrates and attaches to the ischial spine. Sacral ligament attaches to the sacral, coccyx side edge (A5B5); the width of it is male3.29±0.12cm and female3.20±0.10cm. Sacral ligament attaches to the sacral, coccyx from the side edge of the top to the ischial spine (A5C5); the width is men5.28±0.13cm and female5.51±0.13cm. Sacral ligament attached to the sacral, ischial spine distance (B5C5) to the lower edge of the side of the coccyx, the width is male5.06±0.07cm and5.16±0.06cm for women. There is no significant difference between men and women in A5B5; however, significant differences exist between men and women in both A5C5and B5C5.(6) In two cases of pelvic horizontal slice, either the male or the female, the distances between the starting and the ending of the sacroiliac space (M1M2) on both sides are gradually decreasing from the low pelvis horizontal slice to the high one. But the distance between the starting and the ending of the interosseous sacroiliac ligament in pelvic horizontal slice (M2O) present different patterns---male is increase first, and then decrease, but the female is increase from low pelvis to high pelvis. And the M1A2/M2O is decrease, too. N1N2, the coronal plane projection in the human body of M1M2also decrease from low pelvis to high pelvis, al, the angle formed by M1M2and the human body sagittal axis, is always smaller than the a2, which is the angle formed by M2O and the human body sagittal axis both the male and the female. 3.2When the normal sacroiliac joint is exerted load simulating oblique-pulling manipulation, stress of the pelvis is mainly concentrated inside anterior inferior part of the left iliac fossa from the front view, the maximum stress is0.540E+07; the stress of the pelvis is mainly concentrated the junction between ilium and sacrum from the posterior view, the maximum stress is0.694E+07. Stress of the pelvis is mainly concentrated greater sciatic notch of left pelvis from the side view; the maximum stress is0.54E+07. The shift of pelvis is concentrated contralateral pelvis where the ones exerted load. The maximum displacement is the area where is between anterior superior iliac spine and the highest point of iliac on the contralateral pelvis. The minimum displacement is0. The maximum value of internal and external strain of normal sacroiliac joint is8.682×104m. The maximum value of anteropostreior strain is3.337×10-4m; The maximum value of up and down strain of normal sacroiliac joint is3.284×10-4m.3.3The auricular surface of the male sacroiliac joint was in the shape of’L’, and that of the female,’C’.On the anteroposterior X-ray, both the male auricular surface and the female one were found to be located at the lower2/3of the sacroiliac joint space, and the L-shaped and C-shaped auricular surface could not be observed but were demonstrated only as a thin narrow strip. It was also observed that the male auricular surface was longer and narrower than the female one, as is shown in Graphs1and2. On the oblique X-ray, the sacral and iliac surfaces at the opposite side were clearly seen. The male iliac auricular surface covered a wide area and was long and narrow, while the female’s covered a smaller area and was in the shape of a strip, and the sacroiliac joint space at the same side could also be observed, as is indicated in Graphs3and4. On the anteroposterior X-ray, both the anterior and posterior sacroiliac spaces could be observed. Through the thin lead wires fixed alongside the fringe of the sacral and iliac auricular surface, respectively, the structure of the anterior and posterior sacroiliac joint spaces could be observed. The anterior space was observed to be formed by the anterior fringe of the sacral auricular surface and that of the iliac auricular surface, and the posterior space, by the posterior fringe of the sacral auricular surface and the that of the iliac auricular surface. As is demonstrated on the anteroposterior X-ray, the auricular surface of the male sacroiliac joint covered a wide area and was long and narrow, resembling the kidney, while the female’s, covered a smaller area and was in the shape of a strip. As displayed on the oblique X-ray, the range and fringe of the auricular surface of the sacroiliac joint at the opposite side and the whole of the sacroiliac joint space were clearly shown. As displayed by the male pelvic X-ray, AB and CD were single spaces, and BFC and BEC formed the anterior and posterior sacroiliac joint space, respectively. On the female pelvic X-ray, however, AB was shorter, and CD was absent, with Points C and D overlapping. On the oblique X-ray, the auricular surface, anterior space and posterior space could be observed, as is shown by Graphs9and10.3.4(1) The normal sacroiliac joints on the anteroposterior radiography of the pelvis can be classified to three types:①42cases of males(8.8%) and122cases of females(25.7%) were classified as type I, which was called Single gap on both sides type;②376cases of males(79.2%) and222cases of females(46.7%) were classified as type II, which was called Double gaps on both sides type;③57cases of males(12%) and131cases of females(27.6%) were classified as type Ⅲ, which was called One side single gap and the other side double gaps type;(2) Double gaps on both sides type can be particularly classified to four subtypes:①3cases of males(0.8%) and15cases of females(6.6%) were classified as2double gaps type;②212cases of males(56.4%) and155cases of females(69.8%) were classified as12double gaps type;③8cases of males(2.1%) and4cases of females(1.8%) were classified as21double gaps type;④157cases of males(41.8%) and44cases of females(19.8%) were classified as121double gaps type;(3) One side single gap and the other side double gaps type can also be classified to two subtypes:①15cases of males(26.3%) and65cases of females(49.6%) were classified as Single gap on left and double gaps on right type;②42cases of males(73.7%) and66cases of females(50.4%) were classified as Double gaps on left and single gap on right type.Conclusion4.1The sacroiliac joint has strong stability, which is closed related to the structural features of the sacroiliac joints and ligaments. Of them, posterior sacroiliac ligament and Interosseous sacroiliac ligament make a decisive role to the stability of the sacroiliac joint. This study provides the anatomical basis for the clinical research and treatment.4.2The focus of the sacroiliac joint stress is anterior superior border and posterior superior border when the normal pelvis exerted oblique-pulling manipulation. The anterior superior border and posterior superior border of the normal sacroiliac are pulled only by oblique-pulling manipulation with small displacement. The internal and external strain of normal sacroiliac joint is maximal, the second value is anteropostreior strain, the up an dwmn strain of sacroiliac joint is minimal4.3The radiological anatomic characteristics of SJ are presented in the anterposterior and oblique radiography of the pelvis. The observation should focus on the anterior and posterior spaces and the scope of auricular surface of SI joint.It’s suggested that the anteroposterior radiography is enough for meeting the clinical requirement.4.4The most common type of the normal sacroiliac joints on the anteroposterior radiography of the pelvis is the Double gaps on both sides type, in which the largest proportion of all the four subtypes is the "12"double gaps type, but the constituent ratio of each type on gender has a significant variation. |
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