| BackgroundPelvic fractures are mostly caused by high-energy impact accounting for about 3% of skeletal fractures, with high mortality rates ranging from 10% to 16%. Surgical management of pelvic fractures is necessary and widely accepted. Surgical procedure help patients with unstable displaced pelvic ring stabilize the pelvis and improve clinical outcomes. Nowadays, the morbidity and mortality rate have decreased remarkably thanks to the development of treatment concepts and technologies, the treatment of pelvic factures is still a big challenge for orthopaedists.The posterior osseous-ligamentous complex locates in the central of posterior pelvic ring and contributes to about 60% of the pelvic stabilization, being the core transmission load of axial skeleton and lower extremity. Ligaments around the sacroiliac joint such as sacrotuberous ligament (ST)、 sacrospinous ligament (SS) as well as anterior sacroiliac ligament, are critical to sustaining and stabilizing the pelvic. These ligaments could be injured when posterior pelvic ring was damaged.In the Young-Burgess classification of pelvic injuries, the value of 2.5 cm of symphysis pubis diastasis differentiates the a stable pelvic from an rotationally unstable pelvic. Tranditional radiology examination only shows the pathology of the pelvic fracture, but the ligaments. Some researches deduced the injury of ligaments from the SIJ separation or symphyseolysis shown on the image,which were lack of clinical evidences. Although the key role of sacroiliac joint complex has now been acknowledged, the major managements of unstable pelvic fracture mostly focus on the reduction of bony pelvic ring and overlook the repairing of ligaments due to lack of information.MRJ is a kind of radiology examination which can assess the ligaments without invasive operations. Nowadays the MRI become the regular exam for patient with knee-joint injury. However, the integrity of ligament assessed by using MRI have rarely been studied. Current MR-based investigations of the SIJ ligaments mainly refer to the cartilage of the auricular surface or to signs of sacroilitis. But, it has been one of the research hotpots in pelvic. While the understand of the anatomy and biomechanics of sacroiliac joint complex getting deeper and deeper, MRI will be gradually applied to the diagnosis and treatment of pelvic injuries, especially in sacroiliac associated ligaments.The sacrotuberous and sacrospinous ligaments play an important role in sacroiliac joint complex, providing additional support posterior. The sacrospinous ligament lies above the lesser saciatic foramen and below greater saciatic foramen, the base of which attaches to the lateral inferior sacrum while the tip to the spine of the ischium. The sacrospinous ligament restrict the rotation of the sacrum in association with the sacrotuberous ligament, and once if they were traversed, the micromotion of SIJ would increase significantly.For adult, the general position is standard supine, especially for patients with pelvic injuries. After the computer calculate, we usually obtain three different planar image, horizontal plane, sagittal plane and coronal plane. However, due to the specificity of anatomy of sacroiliac ligaments which has different orientations. Surgeon can hardly observe these ligaments, particularly in patients with pelvic injuries. Theoretically, ligaments can better be revealed if the cross-section plane parallel to it. In this case, some researchers measured and calculate the angle between ligaments and three different plane in order to find out the appropriate cross-section plane.Isotropy 3D MRI has higher spatial resolution, and the acquisition of a volume dataset enables clinicians to take measurements. One of the major limitation is that it take to long to collect data. Currently, many MRI sequences has been developed and the application of 3D MRI is more convenient. We can reconstruct the volume data of pelvic by Multi-plannar reconstruction technology in the workspace and adjust the cross-section plane optionally.Long posterior sacroiliac ligament and sacrotuberou ligament has been studied by other reseaschers, instead of sacrospinous ligament. In our study, we locate the insertion of the ligament by observing the specimen, calculate the angle between the sacrospinous ligament and the coronal plane by using the CT data. Finally, obtain the image of the ligament in 3D MRI.ObjectiveThis study is to observe the anatomy properties of sacrospinous ligaments, determine the insertion and direction of it. According to the bony landmark of the insertion of the sacrospinous ligament, measure the angle between the projection of the sacrospinous ligament and coronal plane on sagittal plane on 3D reconstructive model of CT data. At last, Observe the image of sacrospinous ligament in 3D MRI. To provide an effective and convenient way for the diagnosis of sacrospinous ligaments.Part ⅠMethods1.MaterialSpecimen:eight fresh frozen or preservative adult male and female pelvis,supplied by the department of anatomy of south medical university, were used in this study(complete osseous pelvic with pelvic ligament and lumbar 4/5).All the pelvis was Confirmed well, by gross appearance and X-ray, without disease such as fracture, tumor, rheumatism disease or tuberculosis anatomical variations.Experimental apparatus:Orthopedic operating table, Clamps, Saclpel, ruler.2.Anatomy property observation:Eight fresh cadaver specimen were disserted carefully. The ligaments of Sacroiliac joint complex were protected intact. Observe and record the shape, the bony landmark of insertion and the course of sacrospinous ligaments.ResultEight fresh cadaver specimen were disserted carefully. The ligaments of Sacroiliac joint complex were protected intact. The fan-shape sacrospinous ligament passes from the sacrum to the ischial spine. The sacral insertion of the sacrospinous ligament occurred along the 4th sacral vertebral transverse process tubercle to the 1st Coccygeal vertebra transverse process and the fascicles of which girded the insertion at the ischial spine.Part ⅡMethods1.MaterialThe data of whole pelvics of adults scanned by CT in our hospital between 2009.11 to 2011.11 were collected including 25 male and 11 female,whose average old is 50.28, from 17 to 89.None of the models had bone lesions or anatomic variation.2. Measuring the anatomy parameter of the sacrospinous ligament.We imported the data into Mimics 10.01 (Materialise,Belgium) in the format of Dicom, and then got the information of the pelvic edge using the function of grayscale splitting. Extracted these information again with function of region segmentation next, and we rebuilt them into three-dimensional reconstruction. We locate the bony landmark of the insertion of the sacrospinous ligament. Record the corresponding parameter of the landmark. During the data were imported into the software, we identified the orientation to build a space coordinates system. The bony landmark of the two insertion of the sacrospinous ligament can be represented by the parameter of the coordinate we previously recorded in each plane. The angle between the projection of the sacrospinous ligament and coronal plane on sagittal plane can be easily calculated by using trigonometric function.ResultWe measured the angle between the projection of the sacrospinous ligament and coronal plane on sagittal plane. The mean angle of the right and the left side were 60.72±8.22 degree and 62.16±7.88.respectively in 25 females. In 11 males, the mean angle of the right side was 61.04±11.71 and the left side was61.04±9.36. We found that there was no significant differences between the left and the right sides in both genders(P>0.05). The differences between male and female were of no statistical significance(P>0.05). The mean angle of total 72 sacrospinous ligament of 36 pelvics were 61.32±8.71 degree.Part ⅢMethods1. Material10 healthy volunteers were recruited in South Medical University. Philips 3.0T Achieva MRI (supplied by the department of South Medical University Nanfang hospital Medical Image Center). The study protocol was approved by the ethics committee of South Medical University Nanfang hospital and every volunteers signed the freely given informed consents.2. Data collection10 healthy volunteers all receive MRI scaning with a standard supine position, and hands placed on the chest. The MR sequences were 3D mDixon. The parameters for scanning:Thk 3.0/-1.5 mm, FOV 375mm, TR 3.6ms,TE 0.0ms, Matrix 196*384. Transfer the volume data to the workspace and select the multiple planar reconstruction function. Locate the ischial spine in the horizon plane and then spin the cross-section plane in the sagittal plane. Record the present angle when the sacrospinous ligament can integrality be seen on the oblique coronal plane. Previously determined the angle of the cross-section plane as 60±5 degree and record level of the display of the sacrospinous ligament. Compare the level of the display of the ligament on sagittal plane horizon plane and coronal plane with the level of the display of the ligament on oblique coronal plane.3. Image assessmentThe observation were completed by a seniority radiologist with accumulate knowledge of sectional anatomy of pelvic and a seniority orthopedist with rich experience in pelvic therapy. Excellent:the hole ligament and the two insertion of it can be seen. Good:the ligament can party be seen. Poor:the ligament can not be seen.Result20 sacrospinous ligaments of 10 volunteers were observed in the MRI images. The mean angle between the projection of the sacrospinous ligament and coronal plane on sagittal plane we measured on MRI data was 57.53±9.50 degree. After we compared the CT and MRI data, and found that there was no statistical significant differences. The comparison between the oblique coronal plane and the 3 normal plane showed statistical significant differences(P<0.05). The level of the display on oblique coronal plane and the horizon plane were significantly higher than the rest of two. As the rank of the level of the oblique plane were higher than the horizon plane, we can assumed that the 60±5 degree oblique coronal plane is the best cross-section plane for sacrospinous ligament to display.Conclusion1. The fan-shape sacrospinous ligament passes from the sacrum to the ischial spine. The sacral insertion of the sacrospinous ligament occurred along the 4th sacral vertebral transverse process tubercle to the 1st Coccygeal vertebra transverse process and the fascicles of which girded the insertion at the ischial spine.2. We found that there was no significant differences between the left and the right sides in both genders(P>0.05). The differences between male and female were of no statistical significance(P>0.05). The mean angle of total 72 sacrospinous ligament of 36 pelvics were 61.32±8.71 degree.3. The level of the display on oblique coronal plane and the horizon plane were significantly higher than the rest of two. As the rank of the level of the oblique plane were higher than the horizon plane, we can assumed that the 60±5 degree oblique coronal plane is the best cross-section plane for sacrospinous ligament to display. |
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