Basic Medical Research And Clinical Study Of Pelvic Ring Injury

Pelvic ring fractures accounts for 2.3% to 3% of all fractures. A part of fractures are caused by serious trauma and patients often accompany with the nerouvascular injuries and important organ lesions, which may even threaten the life. These patients should be managed promptly and properly to stabilize vital signs and reserve the function to the utmost extend. Because of the anatomical and functional characteristics, severe pelvis ring injuries remain a chanllenge to orthopedic surgeons.The epidemiological information with regard to the pelvic ring factures is rare. Accordingly, we investigated retrospectively the imageological, diagnostic and therapeutical data of the patients in our hospital for a five-year period from 2003 to 2007. We hope it can serve as a reference to learn the epidemiological features of pelvic ring fractures in Hebei Province or even in North China.Separation of pubic symphysis is commen injuries of anterior pelvic ring. It should be treated with internal fixation if the separation is wider than 2.5cm. Separation of pubic symphysis can affect the contact characteristics between the acetabulum and femoral head. Our study showed that separation of pubic symphysis more than 2cm can significantly increase the stress between the acetabulum and femoral head. In order to avoid long-term complications, the stress should be decreased to normal. The strain gauges were applied to study the stress distribution in the intact pelvic ring and the pelvic ring with various separations of pubic symphsis. It can provide biomechanical evidence for the treatment algorism of separation of pubic symphysisPosterior pelvic ring has an important bearing function. Internal fixation is often required for unstable fractures of posterior pelvic ring and it is difficult to achieve anatomical reduction and rigid fixation. Thus, there is still not commenly used methods for unstable fractures of the posterior ring with satisfactory functional recovery. To furtherly improve the stabilization of internal fixation, minimize soft tissue injury, overcome the limitations of the currently used technology and reduce the difficulty of operative procedure, we designed a minimally-invasive adjustable plate (MIAP) for posterior pelvic ring injury based on anatomy and posterior pelvic ring. The MIAP matches well with the anatomy of posterior pelvic ring without prebending. MIAP is fixed close to the sacroiliac complex and dorsal surfase of the sacrum to restore utmostly the posterior pelvic ring biomechanical integrity. MIAP can be applied in a minimally invasive approach with less damage to the soft rissue coverage. The stability of the longitudinal fractures of posterior pelvic ring fixed with MIAP was studied via biomechanical testing, which was compared with the stability fixed with iliosacral screw and tension band plate, respectively. MIAP was used in practice to treat the patients with Tile type B and C fractures of posterior pelvic ring and the preliminary outcomes were analyzed.Part 1 The analysis of epidemiological features of pelvic fracturesObjective To investigate the epidemiological features of patients with pelvic fractures between 2003 and 2007 treated in our hospital.Methods The data of patients with pelvic fractures were collected and analyzed through the PACS system and case reports checking system, the issues including gender, age, injuried sites, and type of AO classification or Young-Burgess classification.Results One thousand nine hundrand fifty three pelvic fractures including 917 males and 930 females were selected, during whom 379 patients were admitted by our hospital. The high risk ages of all patients are between 31 and 40 years. Eighty one cases were combined with acetabular fractures and 312 cases were combined with other parts fracture. The 61-A type fractures are the most common type fractures of AO classification including 766 males and 853 females. The 61-A2 fractures are the most common subtype fractures including 562 males and 433 females. In the Young-Burgess classifications, the most common fractures are of APC type including 119 males and 70 females. The APC-I fractures are the most common subtype fractures including 68 males and 41 females.Conclusion This investigation implied epidemiological features of pelvic fractures between 2003 and 2007 in our hospital. The majority of patients are young and middle-aged and simple fractures are common.Part 2 The retrospective analysis of pediatric pelvic ring fracturesObjective To investigate retrospectively the epidemiological features of 106 pediatric pelvic fractures between 2003 and 2007 managed in our hospital.Methods The data of the children with pelvic fractures were collected and analyzed through the picture archiving and communication system(PACS) and case reports checking system, the issues including gender, age, injured sites and type of Torode and Zieg classification.Results One hundrand and six pediatric pelvic fractures were selected. The patients between 11 and 15 years old made up of the major portion of the case series. There are more male patients than females. The most injure side of the pelvic fractures is the left side and the least is the bilateral injuries. The auto-pedestrian accidents respond for most pediatric pelvic fractures. In Torode and Zieg classification, the major type is type III. Besides pelvic fracture, 19 cases sustained fractures in other parts. Among the patients admitted to our department 44.44% suffered soft tissue injuries, organ injuries or vascular injuries.Conclusion Pediatric pelvic ring fractures are severe injuries, often accompanied with multiple organ trauma. It is important to manage promptly pediatric pelvic fractures associated with soft tissue injury, internal organs or vascular injury at the early stage. Operation should be considered if severe displaced pediatric pelvic fractures exist. The measures for reducing auto-pedestrian accidents can effectively prevent pediatric pelvic fractures.Part 3 The analysis of epidemiological features of sacral fracturesObjective To investigate retrospectively the composition and fracture features of 563 cases with sacral fractures between January 2003 and December 2007 treated in our hospital.Methods The data of patients with sacral fractures were collected and analyzed through the PACS system and case reports checking system, the issues including gender, age, injured sites and type of AO classification or Denis classification.Results Five hundrand sixty three cases of sacral fractures were selected with the following features. There are more female patients than males. The patients between 21 and 50 years make up of the major portion of all patients. Most fractures occur in Autumn and Winter. Falling from height and motor vehicle accidents are the major injury causes. Recently, increasing number of patients suffer from sacral fractures. Among 485 cases of isolated sacral fractures and 78 cases combined with other injury of pelvic ring, the most common injured vertebral body is S5, and the secondary one is S4. The 61-A3 group fracture is the highest frequent type in AO classification. In Denis classifications, the most injured types are Zoneâ…¢.Conclusion The patient population with sacral fractures increases recently, among whom the young and middle-aged is the major portion with lower sacral vertebral body as the main ingredient and with low incidence of accompanied nerve injury. Precautionary measures should be applied in the young and middle-aged people with falling and motor vehicle accidents as the main preventionary issues.Part 4 Biomechanical study of the influnence of symphysis pubis diastasis on the posterior pelvic ringObjective To evaluate the effect of different degrees of diastasis of symphysis pubis on the stress distribution of posterior ring.Methods Eight embalmed pelvis and articulated proximal 1/3 of the femurs were harvested for this study. The sample position simulated both leg standing straight. The strain gages were sticked to 38 sites (symmetrical 19 sites in each side) distributing in the two sides of the sacroiliac joint, anterior sacrum and the posterior ilium. The strain gages were connected with WS3811 digital strainometer to record the strain change and the data during 600N load impacting on the sample at a speed of 10N/second on the CSS-44020 biomechanical machine in intact pelvic ring and 1cm/2cm/2.5cm of diastasis of symphysis pubis.Results Elastic change occurred in the pelvic cortical bone under 600N load. The symmetrical sites had similar strain change without signigicance at each model(P>0.05). The sites with more strain change distributed on the iliofemoral arch in the intact pelvis. The strain change increased significantly in the sites posterior lateral to the iliofemoral arch, and the strain change decreased significantly during diastasis of symphysis pubis.Conclusions The conduct of vertical load in the intact pelvic ring runs along the sacrofemoral arch in general. And it redistributed posteriolaterally in the condition of diastasis of symphysis pubis.Part 5 Biomechanical comparison of the stability of posterior pelvic ring disruptions fixed with three kind of fixatorObjective To analyze the stability of the vertical fracture of posterior pelvic ring fixed with sacroiliac screw, tension band plate and the posterior pelvic ring reconstruction fixator via biomechanical testing.Methods Eight adult male pelvic specimens without osteoporosis were selected. The sacroiliac complex was retained and other soft tissue was removed. The pelvic specimens were fastened to the Bose biomechanical testing machine. Vertical load, ranging from o to 620N, was applied on the specimens at a speed of 20N per second and the displacement was recorded. Then the specimen was exposed to torsional load at a speed of 0.1 degree per second. The rotation degree and the corresponding torque was recorded. Sacral vertical fractures were made. The fractures were reduced anatomically and fixed in turn with sacroiliac screw, tension band plate and the posterior pelvic ring reconstruction fixator. The above mentioned testing protocol was repeated and the testing data was recorded. Paired t tests were employed to analyze the stability of the fixed pelvic specimens.Result The intact pelvis displaces greater than the fixed pelvises under vertical load(P<0.05). Under minor vertical load, the displacement of the pelvis fixed with sacroiliac screw was similar to that of the pelvis fixed with tension band plate(P>0.05). Under major vertical load, the displacement of the pelvis fixed with sacroiliac screw was more severe than that of the pelvis fixed with tension band plate (P<0.05). Under vertical load, the displacement of the pelvis fixed with posterior pelvic ring reconstruction fixator was smaller than that of the pelvis fixed with sacroiliac screw and tension band plate (P<0.05). The torque measured on the intact pelvis displaces was significantly smaller than that of the fixed pelvis under the same torsional load(P<0.05). Under minor torsional load, the torque measured on the pelvis fixed with sacroiliac screw was similar to that of the pelvis fixed with tension band plate(P>0.05). Under major torsional load, the torque measured on the pelvis fixed with sacroiliac screw was significantly smaller than that of the pelvis fixed with tension band plate (P<0.05). Under any torsional load, the torque measured on the pelvis fixed with posterior pelvic ring reconstruction fixator was significantly greater than that of the pelvis fixed with sacroiliac screw and tension band plate (P<0.05).Conclusion The pelvis fixed with posterior pelvic ring reconstruction fixator is more stable than that fixed with sacroiliac screw and tension band plate under both vertical load and torsionalPart 6 The application of minimally invasive adjustable plate in the treatment of posterior pelvic disruptions with minimally invasive percutaneous plate osteosynthesisObjective This study aims to introduce a novel minimally-invasive adjustable plate (MIAP) for posterior pelvic ring injury, describe the surgical technique and present the preliminary radiological and clinical results of the instrument in the management of posterior pelvic disruptions.Methods The MIAP is designed to imitate the structure and function of the posterior pelvic ring. It matches well with the anatomical feature of posterior pelvic ring and it is placed close to the sacroiliac complex and the sacrum. Isolated compressed or separate fracture in the frontal plane of posterior pelvis ring can be reduced by the adjusting the MIAP length. Twenty two patients with posterior pelvic ring injuries were treated with MIAP through a minimally invasive approach from August 2008 to March 2010, including 10 males and 12 females. The fracture patterns consisted of 14 cases of Type C fractures and in and 8 cases of Type B according to Tile classification of fractures. Preoperative and postoperative radiography was conducted to assess the reduction and union. Functional rehabilitation program was individualized and early exercises were encouraged. Patients were followed up and the functional outcome was measured with the use of a scoring system proposed by Lindahl and associates.Result The posterior pelvic ring disruptions were reduced significantly and fixed with the use of MIAP. Thirteen screws were inserted through the medial holes of MIAP into the sacrum without iatrogenic neurovascular injuries. The average duration of surgery was 54 minutes the mean intraoperative blood loss was 85ml for the reduction and fixation of the posterior pelvic ring injuries. The patients were followed up for a mean of 21 months. All patients achieved union. The overall radiological results of the reduction were excellent in 15 patients, good in six patients and fair in one patient. The functional outcome was excellent in 13 patients, good in six and fair in three. Fifteen patients returned to their original jobs and seven patients changed jobs because of the associated injuries. There was no iatrogenic nerve injury, deep infection, failure of fixation or irritative symptoms or pressure sores due to the subcutaneous implantation.Conclusion Treatment of posterior pelvic ring injury with MIAP is an effective technique in view of its convenience, safety, minimal traumatic invasion and lower complications. Favorable clinical and radiological outcomes can be achieved in patients with posterior pelvic disruptions treated with MIAP.