改良Galveston技术与拉力螺钉固定单侧骶髂关节脱位的有限元分析

Objective To explore biomechanical properties of modified Galveston technique and lag screw fixation for dislocation of the unilateral sacroiliac ioint through finite element analysis. Methods Soft-ware Mimics 10.0l and Geomagic 10.0 was used to develop a geometric reconstruction of the pelvis based on the CT scan data.Geometric reconstructions of different internal fixations were also developed using software Solidworks 2007.The models were meshed,assembled and given the material properties through software Hypermesh 10.0.Five models of three-dimensional finite element(3D FE)were established for dislocation of the sacroiliac ioint:double L4-ilium Galveston fixation,double L5-ilium Galveston fixation,single L4-ilium Galveston fixation.single L5-ilium Galveston fixation,and lag screw fixation,Finally the models were imported to software Ansys 10.0.An axial load of 500 N was compressed above the L4 vertebral body.Stress-strain nephograms for the 5 different fixations were compared.and biomechanical stabilities of different internal fixations were analyzed. Results The stress-strain nephograms showed the maximum pelvic stresses in the 5 fixations were respectively 1.690×109Pa(double L4-1 Galveston),1.130×109Pa(double 1.584×109Pa(1ag screw fixation).Displacements of the sacrum were downward,forward,and rightward.The total displacements were respectively 1.589×10-3m,1.871×10-3m,2.404×10～m,2.468×10-3m and 0.308 ×103 m. Conclusions The maximum displacement in bilateral fixation is smaller than that in unilateral fixation with modified Galveston technique.In both bilateral and unilateral Galveston fixations for L4and L5,the maximum displacements are not significantly different,but they are larger than that in lag screw fixation.     

Screw-plate fixation versus non-cannulated screw fixation for Lisfranc ligament injury: A 3-D finite element analysis北大核心CSCD

Objective To compare biomechanical stabilities between screw-plate fixation and non-cannulated screw fixation for Lisfranc ligament injury by a 3-D finite element analysis. Methods A 3-D model of a healthy foot was developed from computed tomography images. The 1st and the 2nd dorsal tarsometatarsal ligaments and Lisfranc ligament were cut in the 3-D model of a healthy foot to establish a Lisfranc ligament injury model, in which screw-plate fixation (with 2 locking plates and 8 standard screws and one non-cannulated screw) and non-cannulated screw fixation (with 3 non-cannulated screws) for Lisfranc ligament injury were simulated respectively. Finite element analyses were carried out by Abaqus 6.14 software after loads were added in the 3-D models of screw-plate fixation and non-cannulated screw fixation for Lisfranc ligament injury. The overall stress-strain nephogram, the stress distribution and displacement of the foot bone, and the stress distribution on the internal fixation system were compared between the 2 kinds of models. Results Under the same load, the stress of the whole screw-plate fixation was concentrated on the fixators, and the stress of the non-cannulated screws was also greater than that of the bones. In both models, the strain of the whole foot led to arch collapse, especially in the medial column. The maximum stress on the screw holes in the medial and middle columns in the screw-plate fixation model was 39.91 MPa, smaller than that in the non-cannulated screw fixation model (53.13 MPa). The relative displacement of the first metatarsal joint in the screw-plate fixation model was 8.515 × 10-1 mm, much greater than that in the non-cannulated screw fixation model (3.893 × 10-1 mm). Stress concentration was observed in both models. The stress of the screw-plate system was concentrated on the fibular side of the middle section of the plate used to fix the first tarsometatarsal joint, decreasing towards both ends. The maximum stress of the non-cannulated screws was located in the middle of the medial column screw for fixation of the first tarsometatarsal joint, significantly greater than those of the both ends. The maximum stress of the screw-plate system was 239.5 MPa, smaller than that of the non-cannulated screws (256.8 MPa). Conclusions Non-cannulated screw fixation demonstrates a greater biomechanical stability for Lisfranc ligament injury than screw-plate fixation. However, the former may have a higher risk of screw breakage because it bears a greater stress. © 2023 Chinese Journal of Orthopaedic Trauma. All rights reserved.     

组配式人工半骨盆假体重建的生物力学分析

Objective To analysis the biomechanical characteristics of the reconstructed pelvis with modular hemi-pelvie prosthesis by finite element (FE) method. Methods A subject-specific finite element model of pelvis was established. Th experiment was performed on the same cadaveric pelvis. Eight points on the surface of cortical bone was determined. Both the same load and boundary conditions were applied on the FE model and experiment. The stress by experiment (σ EXP) was calculated based on the data collected from the strain discs. Linear regression was performed with the stress predicted by FE model (σFEM) and experi-ment data to validate the FE model. A defect pelvic (with zone Ⅱ +Ⅲ in left hemi-pelvis) FE model was con-structed and assembled with the prosthesis. The stress distribution on the eontra lateral hemi-pelvis was cal-culated by the reconstructed pelvic FE model (σRS), and the results were compared with that of the normal pelvis (σNS). Also the comparison was clone at the resection level of the affected hemi-pelvis between normal pelvic FE model (σNR) and reconstructed model (σRR) both on medial and lateral cortical bone of the pelvis. Structural analysis was performed on the whole set of implant. Results FE predictions were strongly correlated with experimental results (R2=0.87). No significant difference was found between the σRS and σNS (t=1.81, P=0.08). Regarding to the stress distribution at lilac resection level, no difference was found between σNR and σRR on the medial side (t=0.47, P=0.65). However, on the lateral side, σRR were signifi-cantly higher than the σNR (t=2.78, P=0.02). The peak stress of the prosthesis was about 183 MPa located at the conjunction of the acetabulum and the iliac fixation part. The main load conduction path on the prosthe-sis was at the posterior side of column portion part of the iliac fixation. Conclusion Reconstruction with modular hemi-pelvic prosthesis could recover the pelvic biomechanics with rational mechanical design.     

改良Galveston技术与拉力螺钉固定单侧骶髂关节脱位的有限元分析

目的 通过对改良Galveston技术与拉力螺钉同定单侧骶髂关节脱位的三维有限元模型进行分析,比较其生物力学稳定性.方法基于CT扫描数据,利用Mimics10.01软件和Geomagic10.0软件埘骨盆模型进行几何重建;利用Solidworks2007软件对内固定器械进行几何重建.导人Hypermesh 10.0软件中进行刚格划分和装配,赋予材料属性.建立右侧骶髂关节脱位双侧L4-髂骨Galveston固定、双侧L5-髂骨Galveston固定、单侧L4-髂骨Galveston同定、单侧L5-髂骨Galveston固定和拉力螺钉固定5种有限元模型.最后导入Ansys10.0软件中,在L4椎体上方模拟施加500 N轴向压缩载荷,分析不同内固定方式的von Mises应力分布和应变分布.结果从应力和应变云图可知,双侧L4-髂骨Galveston固定、舣侧L5-髂骨Galveston固定、单侧L4-髂骨Galveston固定、单侧L5-髂骨Galveston固定及拉力螺钉固定后骨盆的最大应力值分别为1.690×109 Pa、1.310×109 Pa、0.834×109 Pa、0.836×109 Pa、1.584×109 Pa;骶骨相对于左侧髋骨的移位方向为向下、向前和向右,总位移依次为1.589×10-3m、1.871×10～m、2.404×10-3 m、2.468×10-3m、0.308×10-3m.结论各种内固定下 Von Mises应力集中分布于腰髂螺钉与骨质的结合部位.改良Galveston技术双侧固定较单侧固定应变小,无论是双侧固定还是单侧固定,固定于L4和L5的应变无明显差异,但均明显大于拉力螺钉吲定.

Abstract：

Objective To explore biomechanical properties of modified Galveston technique and lag screw fixation for dislocation of the unilateral sacroiliac ioint through finite element analysis. Methods Soft-ware Mimics 10.0l and Geomagic 10.0 was used to develop a geometric reconstruction of the pelvis based on the CT scan data.Geometric reconstructions of different internal fixations were also developed using software Solidworks 2007.The models were meshed,assembled and given the material properties through software Hypermesh 10.0.Five models of three-dimensional finite element(3D FE)were established for dislocation of the sacroiliac ioint:double L4-ilium Galveston fixation,double L5-ilium Galveston fixation,single L4-ilium Galveston fixation.single L5-ilium Galveston fixation,and lag screw fixation,Finally the models were imported to software Ansys 10.0.An axial load of 500 N was compressed above the L4 vertebral body.Stress-strain nephograms for the 5 different fixations were compared.and biomechanical stabilities of different internal fixations were analyzed. Results The stress-strain nephograms showed the maximum pelvic stresses in the 5 fixations were respectively 1.690×109Pa(double L4-1 Galveston),1.130×109Pa(double 1.584×109Pa(1ag screw fixation).Displacements of the sacrum were downward,forward,and rightward.The total displacements were respectively 1.589×10-3m,1.871×10-3m,2.404×10～m,2.468×10-3m and 0.308 ×103 m. Conclusions The maximum displacement in bilateral fixation is smaller than that in unilateral fixation with modified Galveston technique.In both bilateral and unilateral Galveston fixations for L4and L5,the maximum displacements are not significantly different,but they are larger than that in lag screw fixation.     

Finite element study of maxillary Le Fort-Ⅰ osteotomy with rigid internal fixation

Objective To study the biomechanical characteristic of maxillary Le fort- I osteotomy with rigid internal fixation (RIF), so as to choose best fixation method. Methods The 3-dimensional finite element models of maxillary Le Fort- I osteotomy with 9 kinds of RIF methods were established. Then the models were divided into three groups to calculate the stress distribution of the maxilla and the displacement of bone segment under 3 kinds of occlusion condition. The fixation stability of the different RIF methods was evaluated. Results Under the incisor occlusion condition, the stress of the cranio maxillary complex transmits mainly along the nasal-maxillary buttress. Under the premolar and molar occlusion condition, the stress transmits along the alveolar process first, then turns to the nasal-maxillary and zygomatic-maxillary buttress. The focused stress position of the internal fixation system is at the connection between the screws and the plate and at the plate near the osteotomy line. Under the premolar occlusion condition, the displacement of bone segment with different RIF methods was (in a decreasing order) 0.396509 mm ( with bio-absorbable plate), 0.148393 mm (with micro-plate ), 0.078436 mm (with mini-plate ) in group 1;0.188791 mm (fixing at the nasal-maxillary buttress), 0.121718 mm (fixing at the zygomatic-maxillary buttress) , 0.078436 mm (fixing at the both buttress) in group 2;0.091023 mm (with straight plate), 0.078436 mm (with L shape plate), 0.072450 mm (with Y shape plate) , 0. 065617 mm (with T shape plate) in group 3. Conclusions The fixation stability of using the bio-absorbable plate in Le Fort-Ⅰ osteotomy is less stable than using the titanium plate. Fixing at the zygomatic-maxillary buttress is more stable than at the naso-maxillary buttress. The fixation stability is different by using different shapes of plates.     

骨外固定支架技术在踝关节融合与矫形中的应用

目的 探讨骨外固定支架技术在踝关节融合与矫形中的疗效.方法 2001年1月至2009年6月采用外固定支架技术治疗27例踝关节创伤性患者,男18例,女9例;年龄32～68岁,平均41岁.其中创伤性关节炎13例,地方性大骨节病3例,骨关节炎5例,结核性踝关节炎2例,踝关节置换术后失败3例,骨髓炎1例.为保证骨对骨加压接触行外固定支架固定.结果 所有患者术后获6～38个月(平均10个月)随访.随访发现关节无肿胀和疼痛,行走步态和功能明显改善,X线片示关节均获骨性融合.结论 外固定支架技术用于踝关节融合率高,对踝关节感染及复合足踝关节畸形有一定优势性.

Abstract：

Objective To study the curative effect of external fixation in ankle joint arthrodesis.Methods From January 2001 to June 2009, we used external fixation in arthrodesis for 27 cases of traumatic ankle joint They were 18 males and 9 females, with an average age of 41 years (range, 32 to 68 years) . There were 13 cases of traumatic osteoarthritis of the ankle joint, 3 cases of local kaschin beck disease, 5 cases of ankle osteoarthritis, 2 cases of tuberculous ankle arthritis, 3 cases of ankle replacement failure, one case of osteomyelitis. Fibular flap grafts were used in 8 cases, bone autografts in 11 cases, bone allografts in 2 cases,and combined bone grafts in 11 cases. External fixation was applied for all cases to ensure compressive contact between bone ends. Results The patients were followed up for 6 to 38 months (average, 10 months). No pain or swelling was found at the ankle joint. Significant improvements were made in walking gait and function of the ankle. X-ray films verified bony fusion in all cases. Conclusion External fixation can lead to a high rate of bony fusion of the ankle joint, and is advantageous for treatment of ankle infection and combined deformity of the ankle and foot.     

Combined anterior and posterior ring fixation versus posterior ring fixation alone in the management of unstable Tile B and C pelvic ring injuries: A randomized controlled trial

Purpose: Combined anterior and posterior ring (APR) fixation is classically performed in Tile B2 and C1 injuries to achieve superior biomechanical stability. However, the posterior ring (PR) is the main weight bearing portion that is responsible for weight transmission from the upper parts of the body to the lower limbs through the sacrum and the linea terminalis. It is hypothesized that isolated PR fixation can achieve comparable radiological and clinical outco...     

外固定架联合髂腰固定术治疗垂直不稳定型骨盆骨折

目的 探讨应用外固定架联合髂腰固定术治疗垂直不稳定型骨盆骨折的临床效果.方法 对2008年1月至2009年3月收治的9例垂直不稳定型骨盆骨折患者进行手术治疗.男4例,女5例;年龄19～56岁,平均37岁.9例均为Tile C型骨折,其中C1.2型3例,C1.3型6例.采用后路患侧下腰椎旁切口入路,垂直移位复位后,椎弓根钉棒系统固定L4.5椎体和髂后上棘,前路双侧髂前上棘组合式外固定器固定.结果 9例患者术后获得12～18个月随访,平均14.3个月.术后X线片均示骨盆骨折复位满意,后环形态恢复良好;根据Matta骨盆骨折复位评定标准,优6例,良3例.术后2例患者骶丛损伤压迫症状解除,未出现医原性神经、血管损伤.下肢行走、蹲屈功能恢复满意.术后12个月Majeed评分:优7例,良2例.结论 外固定架联合髂腰固定术治疗垂直不稳定型骨盆骨折疗效满意,且具有操作简便、并发症少的特点.

Abstract：

Objective To evaluate the clinical outcomes of external fixator with lumbopelvic distraction spondylodesis in treatment of vertically unstable pelvic fractures. Methods From January 2008 to March 2009, 9 patients (4 males and 5 females) with a vertically unstable pelvic fracture were treated with modular external fixator with lumbopelvic distraction spondylodesis. According to the classification of Tile, 9fractures were classified as type C. This fixation construct comprises a vertical lumbopelvic distraction component which fixed L4.5 and the posterior superior iliac spine and a transverse fixation which fixed anterior iliac spine with external fixator. Results All patients were followed up 12-18 months after surgery, with an average of 14.3 months. Postoperative X-ray showed satisfactory reduction of pelvic fracture. Pelvic fractures healed in all patients without loss of reduction 3-6 months after operation. According to Matta reduction evaluation criteria, 6 patients were excellent and 3 good. For the two patients with sacral neurological injuries,appropriate surgical decompression was performed to improve the symptom and minimize the deformity. No iatrogenic complications of neurovascular injury occurred. Patients now walk unassistedly without pain in the waist or legs, and with no shortening of lower limbs or claudication. By considering symptom and satisfactory scores, the Majeed functional assessment revealed that seven patients had excellent results and two good at one year. Conclusion External fixator with lumbopelvic distraction spondylodesis that allowed early mobilization and ambulation, with general applicability and definite safety, is an effective surgical technique for the treatment of vertically unstable pelvic fracture.     

骶骨切除术后四棒内固定方式重建腰骶部的三维有限元分析

目的 分析骶骨切除术后四棒内固定方式重建腰骶部的生物力学特点.方法 利用CT图像建立骶骨次全切除和全骶骨切除有限元模型.在次全切除模型上比较四棒内固定方式与改良Galveston技术重建时L3椎体在垂直压缩、前屈、后伸、左侧弯和右旋工况下的活动范围及内固定器械最大应力值.在全切除模型上比较两种重建方式在垂直压缩工况下L3椎体的活动范围和内固定器械最大应力值.结果 (1)在次全切除模型上,四棒内固定后L3椎体在各种工况下的活动范围分别为4.2mm、0.49°、0.49°、0.24°和0.26°,改良Galveston技术重建后分别为5.5 mm、0.74°、0.74°、0.27°和0.30°.四棒内固定后各种工况下器械最大应力值分别为810.7、148.0、148.0、134.6、14.4 Mpa,改良Galveston技术重建后分别为655.0、109.9、109.9、119.1、11.4 MPa.(2)在全切除模型上,四棒内固定后垂直压力下L3椎体位移和器械最大应力值分别为10.9 mm和2172 MPa,改良Galveston技术重建后分别为49.1 mm和4325 MPa.结论 与改良Galveston技术相比,四棒内固定方式重建腰骶部具有较强的刚度.在全骶骨切除且不行腰骶部植骨时,四棒内固定方式具有较小的最大应力值,可降低内固定器械早期失败的风险.但在骶骨次全切除或行腰骶部植骨时,其应力遮挡效应明显增加.

Abstract：

Objective To analysis the biomechanical properties of four-rod fixation system for lumbosacral reconstruction after sacrectomy.Methods Two finite element models of lumbosacral area were established according to pelvic CT images:a subtotal saerectomy model and a total sacrectomy model.The range of motion of L3 vertebral body and max yon Mise stress of instruments of a novel four-rod fixation system were evaluated and compared with those of modified Galveston technique(MGT)under conditions of veaebral body and max von Mise stress of instruments of the four-rod fixation system were evaluated and compared with those of MGT under vertical compression.Results In subtotal sacreetomy model,the range of motion of L3 vertebral body in the four-rod fixation system were 4.2 mm,0.49°,0.49°,0.24°and 0.26°compared to 5.5 mm.0.74°,0.74°,0.27°and 0.30°in the MGT.The max von Mise stress of instruments in the four-rod fixation system were 810.7,148.0,148.0,134.6 and 14.4 MPa,compared to 655.0,109.9,109.9,119.1 and 11.4 MPa in the MGT.In total sacrectomy model under veaical compression,the range of motion of L3 vertebral body and max van Mise stress of instruments in the four-rod fixation system were 10.9mm and 2172 MPa compared to 49.1 mm and 4325 MPa in the MGT.Conclnsion Comparing with the MGT.the four-rod fixation system was stiffer and showed a significant increase in the stability of lumbosacral area.When total sacrectomy without bone graft were performed,the max stress of the four-rod fixation system was much lower than that of the MGT,which means smaller risk of instrument failure.When subtotal sacrectomy or bone graft were performed,despite better stability,the higher stress shielding-effect of the four-rod fixation svstem might be unfavorable for bone fusion,which still need to be evaluated by clinical trials.     

Biomechanical effect of vertebropiasty on the adjacent intervertebral levels using a three-dimensional finite element analysis

Objective: To investigate the biomechanical effect of different volume, distribution and leakage to adjacent disc of bone cement on the adjacent vertebral body by three-dimensional osteoporosis finite element model of lumbar. Methods: L4 -L5 motion segment data of the cadaver of an old man who bad no abnormal findings on roentgenograms were obtained from computed tomography (CT) scans. Three-dimensional model of L4-L5 was established with Mimics software, and finite element model of L4-L5 functional spinal unit (FSU) was established by Ansys 7. 0 software. The effect of different loading conditions and distribution of bone cement after vertebroplasty on the adjacent vertebral body was investigated. Results: This study presented a validated finite element model of L4-L5 FSU with a simulated vertebroplasty augmentation to predict stresses and strains of adjacent untreated vertebral bodies. The findings from this FSU study suggested the endplate and disc stress of the adjacent vertebral body was not influenced by filling volume of bone cement but unipedicle injection and leakage to the disc of bone cement could concentrate the stress of adjacent endplate. Conclusions: Asymmetric distributions and leakage of cement into intervertebral disc can improve the stress of endplate in adjacent vertebral body. These results suggest that optimal biomechanical configuration should have symmetric placement and avoid leakage of cement in operation.     

不同方法治疗不稳定骨盆骨折中前环损伤的有限元分析

目的:比较5种不同固定方法治疗不稳定骨盆骨折中前环损伤的生物力学稳定性,为临床治疗提供参考。方法:使用三维有限元方法,建立一侧骶髂关节脱位合并耻骨支骨折的不稳定骨盆骨折模型(Tile C型),模拟前方采用5种不同的固定方法,后方统一采用骶髂螺钉进行固定,并在模拟站立状态下比较分析不同组合固定方法治疗后的骨盆环的von Mises应力及应变分布情况。结果:竖直方向500 N载荷加载后,前方骨折处最大应力3.56 MPa(前方外固定架组),骶髂关节和骨折处总位移和Y轴上垂直位移在应力下均未超过1.5 mm。其中前方经皮入路组和前方外固定架组在内固定、骨折前方、骶髂关节处的最大应力明显大于改良Stoppa入路组、传统的髂腹股沟入路组、空心螺钉组,且在骶髂关节和骨折处的总位移和Y轴上垂直位移也大于其他3组。结论:不稳定性骨盆骨折中的前环损伤在5种组合方法植入物的固定后均能得到明显的改善,但采用改良Stoppa入路、髂腹股沟入路、前方空心钉固定方法治疗前环损伤在生物力学总体性能要优于前方经皮入路和前方外固定架治疗的方法。     

Sacroiliac screw fixation for tile B fractures

BACKGROUND: The purpose of this comparative cadaveric study was to investigate whether the stability of partially unstable pelvic fractures can be improved by combining plate fixation of the symphysis with a posterior sacroiliac screw. METHODS: In six specimens, a Tile B1 (open-book) pelvic fracture was created. We compared the intact situation with isolated anterior plate fixation and plate with sacroiliac screw fixation. Using a three-dimensional video system, we measured the translation and rotation stiffness of the fixations and the load to failure. RESULTS: Neither absolute displacements at the os pubis or at the sacroiliac joint nor stiffness of the ilium with respect to the sacrum were significantly different for the techniques with or without sacroiliac screw or the intact situation. Load to failure was reached in only one of the six cases. In all other cases, the fixation of the pelvis to the frame failed before failure of the fixation itself. In these cases, a load of approximately 1,000 N or more could be applied. CONCLUSION: The addition of a sacroiliac screw in a Tile B1 fracture does not provide significant additional stability. Although cyclic loading was not tested, in these experiments forces could be applied that were similar to full body weight. Clinical experiments into direct postoperative weight bearing are recommended to examine the clinical situation.     

Reconstruction of type II+III pelvic resection with a modular hemipelvic endoprosthesis: a finite element analysis study

Objective: To conduct a biomechanical study of the whole reconstructed pelvic ring using a modular hemipelvic endoprosthesis. Methods: A subject‐specific finite‐element (FE) model of the whole pelvic ring, including the pelvis, sacrum and main ligaments, was constructed. Type II+III pelvic resection was simulated on the FE model. Then a three‐dimensional model of a reconstructed pelvic ring with a modular hemipelvic endoprosthesis was developed, and FE analysis performed to compare the stresses along the bilateral arcuate lines of the reconstructed and normal pelvis in the bipedal standing position. Comparison between bilateral stress distributions along the sciatic notch was also performed. The characteristics of load transmission within the endoprosthesis were also studied. Results: No significant difference in the stresses along the bilateral arcuate lines was observed between the reconstructed and normal pelvis. The stress distribution on the prosthesis along the sciatic notch paths was significantly greater than that on the unaffected side in the same position. The peak stress of the implant on the S1 vertebral body was 182.9 MPa under a load of 600N. Study of load transfer on the implant showed that the posterior side of the column between the point of iliac fixation and the acetabulum was subject to the greatest stress. Conclusion: This FE study showed that a modular hemipelvic endoprosthesis can restore load transfer between the sacrum and acetabulum on simple standing. Future implant design should aim to decrease the stress concentration and make the biomechanical performance more balanced.     

Cyclic loading of sacroiliac screws in Tile C pelvic fractures

BACKGROUND: To investigate the stiffness and strength of completely unstable pelvic fractures fixated both anteriorly and posteriorly under cyclic loading conditions, the authors conducted a randomized, comparative, cadaveric study. METHODS: In 12 specimens, a Tile C1 pelvic fracture was created. The authors compared the intact situation to anterior plate fixation combined with one or two sacroiliac screws. In 2,000 measurements, each pelvis was loaded with a maximum of 400 N. The translation and rotation stiffness of the fixations were measured using a three-dimensional video system. Furthermore, the load to failure and the number of cycles before failure were determined. RESULTS: Both translation and rotation stiffness of the intact pelvis were superior to the fixated pelvis. No difference in stiffness was found between the techniques with one or two sacroiliac screws. However, a significantly higher load to failure and significantly more loading cycles before failure could be achieved using two sacroiliac screws compared with one screw. CONCLUSION: Although the combination of anterior plate fixation combined with two sacroiliac screws is not as stable as the intact pelvis, in this study, embalmed aged pelves could be loaded repeatedly with physiologic forces. Given the fact that the average trauma patient is younger and given the fact that the quality (or grip) of the fixation was a significant covariable for longer endurance of the fixation, this suggests that direct postoperative weight bearing could be possible if these results are confirmed in further research.     

前路双重建钢板固定结合植骨治疗难复性TileC型骶髂关节骨折脱位

目的探讨采用前路双重建钢板固定植骨治疗难复性TileC型骶髂关节骨折脱位的临床疗效。方法对39例难复性TileC型骶髂关节骨折脱位采用前路双重建钢板进行固定,取髂骨松质骨植骨。结果所有患者获平均18（8—24）个月的随访,骶髂关节在解剖位或功能位融合。3例术前合并腰骶丛不完全损伤者,在3-4个月内完全恢复。按照Tornetta和Matta复位评定标准：优24例,良8例,可7例,优良率82．1％。根据Majeed功能评分系统：优22例,良9例,可8例。优良率79．5％。结论采用前路双重建钢板固定与植骨治疗难复性TileC型骶髂关节骨折脱位可获得满意复位、固定可靠、稳定性好。有利于骶髂关节融合、并发症少、可使患者早期康复。     

19例Tile C型骨盆骨折的诊治

目的总结Tile C型骨盆骨折的诊治经验,以减少病残。方法对19例Tile C型骨盆骨折患者在血流动力学稳定后进行切开复位内固定和（或）外固定支架固定治疗,术后在X线片上测量骨盆骨折分离移位的最大距离。结果患者均获随访,时间12-60个月。骨折均愈合,无畸形愈合,无步态失常,无下肢不等长、骶髋痛或轻微疼痛。按Majeed骨盆骨折功能评分：满意13例,良好4例,差2例。据Matta评定标准,满意13例,良好6例。结论 Tile C型骨盆骨折的诊治应遵循损害控制原则和内脏损伤情况,按骨折类型和骨折是否开放进行切开复位内固定和（或）外固定支架固定。     

骶髂关节前入路钢板治疗骨盆后环损伤17例

目的：评价骶髂关节前入路钢板治疗骨盆后环损伤的临床疗效。方法：回顾性分析骶髂关节前入路钢板治疗骨盆后环损伤17例临床效果。结果：17例中TileB型8例,C型9例,双钢板治疗5例,单钢板12例,手术时间平均3．6h（2．0-4．5h）,平均出血1800ml（800-4200m1）,14例随访平均27．4个月（6-42个月）,后环损伤平均移位16mm（4-28mm）,骨折愈合,轻度跛行3例。无感染发生。结论：骶髂关节前入路钢板治疗骨盆后环损伤能获得良好的复位和稳定的固定。     

Biomechanical study of four kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation: A finite element analysis

ObjectiveTo compare the biomechanical stability of four different kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation.MethodsFinite element models of unstable Tile type B and type C pelvic ring injuries were created in this study. Modelling was based on fixation with a single S1 screw (S1-1), single S2 screw (S2-1), two S1 screws (S1-2) and a combination of a single S1 and a single S2 screw (S1–S2). The biomechanical test of two types of pelvic instability (rotational or vertical) with four types of percutaneous fixation were compared. Displacement, flexion and lateral bend (in bilateral stance) were recorded and analyzed.ResultsMaximal inferior translation (displacement) was found in the S2-1 group in type B and C dislocations which were 1.58 mm and 1.90 mm, respectively. Maximal flexion was found in the S2-1 group in type B and C dislocations which were 1.55° and 1.95°, respectively. The results show that the flexion from most significant angulation to least is S2-1, S1-1, S1-2, and S1–S2 in type B and C dislocations. All the fixations have minimal lateral bend.ConclusionOur findings suggest single screw S1 fixation should be adequate fixation for a type B dislocation. For type C dislocations, one might consider a two screw construct (S1–S2) to give added biomechanical stability if clinically indicated.