摘要:目的:研究生物降解聚DL乳酸(PDLLA)自锁式捆绑带固定骨折的生物力学性能。方法:80只新西兰大白兔随机分为两组,建立股骨干非负重骨折动物模型,应用生物降解自锁式捆绑带固定骨折为实验组,钢丝固定骨折为对照组,分别于术后1、4、8、12周行生物力学检查进行比较。结果:捆绑带组在术后4、8、12周均比钢丝组的弯曲强度高,但4周、12周时Pgt;005,无统计学差异,8周时Plt;005,提示有统计学差异。离体同种固定物不同时间段抗拉强度自身比较:钢丝固定术后4阶段抗拉强度比较Pgt;005,任何两两比较都没有统计学差异,抗拉强度未随术后时间延长发生明显下降。捆绑带固定术后4周与术后1周比较Pgt;005,抗拉强度无明显降低,但术后8周和术后12周时Plt;005,抗拉强度明显下降。结论:生物降解自锁式捆绑带在非负重骨折治疗中可发挥良好的固定作用。生物降解自锁式捆绑带降解时,应力传导促进了骨折的愈合。Abstract: Objective: To study the biomechanics function of selflocking cerclage band made of biodegradable material polyDLlactic acid (PDLLA) in the fixation of fractures. Methods: Eighty rabbits were divided into two groups. Femur fracture models were made. Fractures were fixed using biodegradable selflocking cerclage band in experimental group and metal fixation material in control group. The biomechanics was analyzed and compared after 1, 4, 8 and 12 weeks respectively． Results: The bending strength of experimental group is more ber than that of control group after 4, 8 and 12 weeks, but it was not statistically significant at 4 and 12 weeks (Pgt;005). It was statistically significant at 8 weeks (Plt;005). The tensile strength of the same cerclage instrument was compared at different stage in vitro, and the result of the control group was not statistically significant at the four stage (〖WTBX〗P〖WTBZ〗gt;005). Regarding the changes of tensile strength of the cerclage instrument at different stage, the result of the experimental group was not statistically significant after 1 and 4 weeks (Pgt;005). However, the decrease of tensile strength was statistically significant after 8 and 12 weeks (Plt;005). Conculsion: Biodegradable selflocking cerclage band could be used in thetreatment of nonweightbearing fractures. The stress force conducting promotes healing of fracture when the selflocking biodegradable cerclage band degrades.
ObjectiveTo introduce the surgery method to reset and fix tibial plateau fracture without opening joint capsule, and evaluate the safety and effectiveness of this method. MethodsBetween July 2011 and July 2013, 51 patients with tibial plateau fracture accorded with the inclusion criteria were included. All of 51 patients, 17 cases underwent open reduction and internal fixation without opening joint capsule in trial group, and 34 cases underwent traditional surgery method in control group. There was no significant difference in gender, age, cause of injury, time from injury to admission, side of injury, and types of fracture between 2 groups (P>0.05). The operation time, intraoperative blood loss, incision length, incision heal ing, and fracture healing were compared between 2 groups. The tibial-femoral angle and collapse of joint surface were measured on X-ray film. At last follow-up, joint function was evaluated with Hospital for Special Surgery (HSS) knee function scale. ResultsThe intraoperative blood loss in trial group was significantly less than that in control group (P<0.05). The incision length in trial group was significantly shorter than that in control group (P<0.05). Difference was not significant in operation time and the rate of incision heal ing between 2 groups (P>0.05). The patients were followed up 12-30 months (mean, 20.4 months) in trial group and 12-31 months (mean, 18.2 months) in control group. X-ray films indicated that all cases in 2 groups obtained fracture heal ing; there was no significant difference in the fracture healing time between 2 groups (t=1.382, P=0.173). On X-ray films, difference was not significant in tibial-femoral angle and collapse of joint surface between 2 groups (P>0.05). HSS score of the knee in trial group was significantly higher than that of control group (t=3.161, P=0.003). ConclusionIt can reduce the intraoperative blood loss and shorten the incision length to use open reduction and internal fixation without opening joint capsule for tibial plateau fracture. Traction of joint capsule is helpful in the reduction and good recovery of joint surface collapse. In addition, the surgery without opening joint capsule can avoid joint stiffness and obtain better joint function.
ObjectiveTo study the effectiveness of a new anterolateral approach of distal femur in the treatment of type C distal femoral fractures by comparing with traditional lateral and anterolateral approaches. MethodsThe clinical data of 51 patients with type C distal femoral fractures treated between January 2008 and August 2011 were retrospectively analyzed. Of 51 patients, 24 patients received the new anterolateral approach of distal femur combined with fixation of condylar buttress plate (modified group), and 27 patients underwent traditional lateral or anterolateral approach combined with fixation of condylar buttress plate (traditional group). There was no significant difference in gender, age, injury cause, American Society of Anesthesiologist (ASA) classification, side, fracture type, complication, and the time from injury to operation between 2 groups (P>0.05). The operation time, intraoperative blood loss, frequency of intraoperative fluoroscopy, hospitalization time, fracture healing time, and Hospital for Special Surgery (HSS) scores of the knee at 3, 6, and 12 months were recorded. ResultsThe operation was successfully completed and the incision healed by first intention in all patients. The operation time and frequency of intraoperative fluoroscopy of modified group were significantly less than those of traditional group (P<0.05). But the intraoperative blood loss and the hospitalization time showed no significant difference between 2 groups (P>0.05). All patients were followed up 12-37 months (mean, 21.3 months). X-ray films showed all fractures were union. The fracture healing time was (12.92±2.24) weeks in the modified group and (13.24±2.52) weeks in the traditional group, showing no significant difference (t=0.476, P=0.637). The knee HSS scores of modified group were significantly higher than those of traditional group at 3, 6, and 12 months after operation (P<0.05). There was no significant difference in the incidence of knee varus or valgus, leg length discrepancy, internal fixator loosening, flexing dysfunction of knee, traumatic arthritis of knee, and total complications between 2 groups (P>0.05). ConclusionComparing with traditional lateral and anterolateral approaches, using the new anterolateral approach to treat type C distal femoral fractures has the advantages of less damage to soft tissue, excellent exposure, less operation time, and frequency of intraoperative fluoroscopy, and better postoperative rehabilitation of knee joint.
This study aims to analyze the biomechanical stability of Magic screw in the treatment of acetabular posterior column fractures by finite element analysis. A three-dimensional finite element model of the pelvis was established based on the computed tomography (CT) and magnetic resonance imaging (MRI) data of a volunteer and its effectiveness was verified. Then, the posterior column fracture model of the acetabulum was generated. The biomechanical stability of the four internal fixation models was compared. The 500 N force was applied to the upper surface of the sacrum to simulate human gravity. The maximum implant stresses of retrograde screw fixation, single-plate fixation, double-plate fixation and Magic screw fixation model in standing and sitting position were as follows: 114.10, 113.40 MPa; 58.93, 55.72 MPa; 58.76, 47.47 MPa; and 24.36, 27.50 MPa, respectively. The maximum stresses at the fracture end were as follows: 72.71, 70.51 MPa; 48.18, 22.80 MPa; 52.38, 27.14 MPa; and 34.05, 30.78 MPa, respectively. The fracture end displacement of the retrograde tension screw fixation model was the largest in both states, and the Magic screw had the smallest displacement variation in the standing state, but it was significantly higher than the two plate fixations in the sitting state. Magic screw can satisfy the biomechanical stability of posterior column fracture. Compared with traditional fixations, Magic screw has the advantages of more uniform stress distribution and less stress, and should be recommended.