The Mechanism Of Ligament Injury When The Semi-pelvic Is Extorted And The Clinical Case Study Of Sagittal Plane Rotational Displacement In Unstable Pelvic Fractures

BackgroundAS we all konw,The treatment of pelvic fractures has gone through half a century in dispute.but now the diagnosis and treatment of pelvic fracture is still a problem for orthopedic surgeons.we used to take a more consevative treatment before we get a better understanding of pelvics.With the development of internal fixation technology and konwledge of pelvic fractures,we tend to take a more positive treatment programs.Sacroiliac joints are important structures to transfer the body load,The integrity of its anatomical and functional is crucial for stabilizing the pelvic ring.However,we pay more attention to the restoration of bone structure in the surgical treatment of pelvic fractures, but the importance of ligament damage has not attract enough attention.So the lone-term functional outcomes of sacroiliac joint injury are often unsatisfactory.In this experiment,we want to study the mechanism of sacroiliac joint ligament when the semi-pelvic is extorted.We are trying to learn more about the mechanics of the ligaments around the joints,in order to promote the clinical treatment of pelvic fracture.The stabilization system of sacroiliac joint includes the stablization of bone structure and the stabilization of soft tissue tructure,the stablization of bone structure mainly depends on the shape of the Sacrum and ilium,the stabilization of soft tissue tructure mainly depends on the ligamengts around the sacroiliac joint.Ligaments around the sacroiliac joint include Interosseous sacroiliac ligament, anterior sacroiliac ligament, posterior sacroiliac ligament, sacrospinous ligament, sacrotuberous ligament and iliolumbar ligament, Ligaments play an important role in maintaining the stability of the sacroiliac joint, With a better understanding of the ligaments around the sacroiliac joint,Currently clinicians determine the type of pelvic fractures mainly depend on the change of the bone structure in the X-ray image data and CT.Current diagnostic methods can not accurately judge the injury of sacroiliac ligaments, The research of sacroiliac ligaments of domestic scholars mainly focuse on the morphological and static biomechanics, ligament injury dose not link with the type of fracture, it is difficult to guide clinical practice issues. The pelvic has an irregular spatial structure and complex mechanism,Thus the displacement of unstable pelvic fracture in three-dimensional space is very complex, both anterior and posterior, lateral displacement, axial displacement, but also vertical shift, sagittal or coronal plane in different directions of rotation shift.Now there is no pelvic fracture classification according to the different shifts, in the conventional type of pelvic fractures, internal and external rotation of the horizontal displacement and vertical displacement are described more, but also the mechanism, These shift is also easier to describe and diagnose by X-ray and CT imaging.But there is little description of rotate shifts in the sagittal plane, and it is also difficult to find in the ordinary X-ray and CT scan imaging,The rotational displacement in the sagittal plane of pelvic fractures is also a fundamental shift in the way, it is also a common shift mode in clinical work, The selection of rotate axis has no impact on the morphological changes when pelvic purely rotate in the sagittal plane,So in the first part we do some reserch on the relationship of pelvic external rotation and the injury mechanism of the sacroiliac ligament,In the second part we measured the sagittal plane rotationnal displacement of unstable pelvic fractures radiologically and determine the type of fracture,analyze different types of shift ratio and its clinical significance.Part I The mechanism of ligament injury when the semi-pelvic is extorted and the role of sacrospinous ligament and sacrotuberous ligament when semi-pelvic rotate in the sagittal planeOb ject ive:This study was designed to study the injury mechanism of ligaments around the sacroiliac joint when semi-pelvic do external rotation movement and to determine the role of sacrospinous ligament and sacrotuberous ligament when semi-pelvic rotate in the sagittal plane.Methods:Complete pelvis specimens were separated from 10 unembalmed/fresh cadavers (female=3, male=7), with the complete section of L5 and complete preservation of pelvic ligaments. Pelvis and lower extremities were separated by hip nodules amputation, we should avoid ligament injuries when release the soft tissue of the pelvis, The specimens were divided into 2 groups randomly, and the test models were set up for two types of external rotation injuries of the pelvis:The group of fixed hemipelvis (the limited group), and the unfixed hemipelvis group (the unlimited group). Then the external rotation injuries of the pelvis, and the final data components were acquired from the biomechanical equipment which recorded the angle displacement under each torque. The biomechanical torque curve recorded a transition time point of the anterior sacroiliac ligament fracture when all the anterior sacroiliac ligament of all specimens in this study presented fracture or severe distortion. In the limited group we found the anterior sacroiliac ligament break first, then the sacrospinous ligament and sacrotuberous ligament when semi-pelvics did external rotation motion,In the unlimited group the sacrospinous ligament and sacrotuberous ligament did not break when the external rotation motion.Then we have the test of rotation in the sagittal plane, according to documents we gave the pubic tubercle a vertical upward force,Since the sacroiliac joints were not separated completely, it will form a sagittal rotational movement of the sacroiliac joint axis.It may be elevated from the increased distance of the pubic tubercle to judge the degree of sagittal rotational displacement,Then we can calculate the effect of the sacrospinous ligament and the sacrotuberous ligament to limit the rotational displacement in the sagittal plane.Results:As was shown in the limited groups and the unlimited groups, with the failure of the anterior sacroiliac ligament, In the unlimited group, during the anterior sacroiliac ligament fractures, there were no obvious injuries or fractures found in the sacrospinous ligament or the sacrotuberous ligament. However, in the limited group, we found 1 case of the sacrotuberous ligament fracture, and 3 cases of the sacrospinous ligament fractures. The sequence of broken is the anterior sacroiliac ligament,then the sacrospinous ligament,at last the sacrotuberous ligament. In the second part,after the broken of the anterior sacroiliac ligament,we lift the pubic tubercle after we cut sacrospinous ligament,the average distance of the pubic tubercle moved up was 20.0±0.9301mm,we lift the pubic tubercle after we cut sacrotuberous ligament,the average distance of the pubic tubercle moved up was 13.5±0.9301mm.,Conclusion:In this study, we had the following several major findings. Firstly, when the limied group were extorted,the fracture order of the ligament was anterior sacroiliac ligament, sacrospinous ligament, sacrotuberous ligament.During the fractures of the anterior sacroiliac ligament, there were no obvious injuries or fractures of the sacrospinous ligament or the sacrotuberous ligament, while there were injuries in all specimens of the limited group. Secondly, we would observed the vertical displacement and rotation in the sagittal plane after the interosseous ligaments and sacroiliac ligaments were broken.Thirdly,the sacrospinous ligament have a more importance effort to restrict the rotation displacement of the semi-pelvic than sacrotuberous ligamentPart II:The Clinical Case Study of Sagittal Plane Rotational Displacement in Unstable Pelvic FracturesObjective:Measure the sagittal plane rotationnal displacement of unstable pelvic fractures radiologically and determine the type of fracture, analyze different types of shift ratio and its clinical significance.Methods:We retrospectively reviewed 82 patients (2005.6-2015.6) with a unilateral fracture of the pelves(43years±18,48 males and 34 females, Tile B 48 patients and Tile C 34 patients). Pelvic ring displacement was identified and recorded radiographically.the sagittal plane rotational displacements were determined by measuring the changed distances from the top of iliac crest to the lowest point of ischial tuberosity or to the pubic tubercle. After the data were collected, use statistical methods to analyze the ratio of different fractures and their clinical significance.Results:Based on radiographic evidence,36 showed sagittal plane rotationnal displacement,of which 28 (77.8%) showed supination displacement and 8 (22.2%) showed pronation displacement. All fractures were grouped based on the pattern of Tile classification:Tile B 48 patients and Tile C 34 patients. Twenty-two cases of Tile B (43.8%) and 14 cases of Tile C (44.1%) showed sagittal plane rotational displacement, In this study, closed reduction including internal fixation and external fixation were successfully accomplished in 71 cases (86.6%). The success rate of closed reduction in pronation and supination displacement groups was 62.5% and67.8%, respectively. The success rate of closed reduction between sagittal plane rotational displacement of pelvic fracture was lower than in all the unstable pelvic ring fractures in this study.Conclusion:The sagittal plane rotation (pronation and supination) displacement of pelvic fractures can be measured by special points and lines on the radiographs. The displacement in sagittal plane supination is more popular.The unstable pelvic fracture which showed sagittal plane rotational displacement is more difficult to reduct.