Three-dimensional finite element analysis of intramedullary nail with different materials in the treatment of intertrochanteric fractures

Intramedullary nails are the common treatment options for femoral intertrochanteric fractures. However, aseptic loosening is considered to be one of the primary forms of failure that can be caused by the stress shielding between the bone and implants. The matching in mechanical properties of implant and bone is a key issue to prevent this failure. Polyetheretherketone (PEEK) and Function-graded (FG) materials are widely used in clinical because of their excellent mechanical properties. In this study, to investigate the biomechanical behaviors of intramedullary nails made of Ti-6Al-4V alloy, Stainless Steel (SS), PEEK and two FG materials, three-dimensional finite element models of intertrochanteric fracture femur with intramedullary nail were constructed with ABAQUS. The maximum von Mises stress on the femoral fracture surface fixed by PEEK intramedullary nail was the largest, followed by FG intramedullary nail, which help stimulate bone growth and subsequently reduce fracture healing time. Compared with traditional metal intramedullary nails, PEEK and FG implants might increase von Mises stress along the same path in the proximal femur. The results showed that PEEK and FG intramedullary nails obviously changed the stress distributions in the bone and reduced stress shielding. This finding indicated that PEEK and FG intramedullary nails have the potential to become alternatives to the conventional metal intramedullary nails.     

胫骨残端长度对前交叉韧带重建术后本体觉恢复的影响

目的:研究保留韧带胫骨残端的长度对前交叉韧带重建术后膝关节本体觉恢复的影响.方法:自2011年3月至2011年12月于我院骨科就诊的42例前交叉韧带重建患者分为3组,每组14例.A组保留韧带胫骨残端长度15～20 mm,男8例,女6例,平均年龄(28.2±6.6)岁;B组保留韧带胫骨残端5～10 mm,男9例,女5例,平均年龄(27.9±6.4)岁;C组保留韧带胫骨残端小于2 mm,男9例,女5例,平均年龄(28.6±6.8)岁.治疗前后采用Lachman试验、前抽屉试验对稳定性进行评价,行Lysholm评分和Tegner评分评价关节功能,采用非负重位被动重复位置法对膝关节本体觉进行检测.结果:3组患者术后6个月Lachman试验、前抽屉试验均为阴性,12、18个月3组各1例前抽屉试验呈弱阳性.术后18个月Lysholm和Tegner评分均高于术前,而术后18个月3组间差异无统计学意义.屈曲20°和伸直80°、20°测试重复位置觉显示,3组在治疗前后差异无统计学意义.屈曲50°和伸直50°测试重复位置觉显示,A组和B组在术后6个月较治疗前好转,且明显优于C组;术后18个月3组差异无统计学意义.屈曲80°测试重复位置觉显示,A组和B组在术后12个月较治疗前好转,且明显优于C组;术后18个月3组差异无统计学意义.结论:保留韧带胫骨残端有助于前交叉韧带重建术后早期本体觉的恢复,残端长度以5～10 mm为宜.     

改良分次酶消化法分离培养兔肌腱干细胞及诱导分化鉴定

目的  采用改良分次酶消化法体外分离培养家兔肌腱干细胞,观察其生物学特性,并进行诱导分化及鉴定。方法  无菌条件下取出家兔髌腱组织,分别运用改良的分次酶消化法和酶消化后低密度稀释接种法进行分离、培养、传代,用倒置相差显微镜观察细胞形态特征并绘制两种方法的生长曲线,通过流式细胞鉴定仪检测肌腱干细胞表面抗原标志物的表达,取P3-P4代肌腱干细胞向成骨细胞、成软骨细胞诱导分化并鉴定。结果  改良的分次酶消化法较酶消化后低密度稀释接种法细胞增殖速度加快,形态均一,杂质细胞少。分离出的肌腱干细胞表面抗原标志CD90、CD44呈阳性,而CD34、CD14呈阴性,证实之前分离的细胞为肌腱干细胞。鉴定出肌腱干细胞具有向成骨细胞和成软骨细胞分化能力。结论  采用改良的分次酶消化法分离培养兔肌腱干细胞简单易行,肌腱干细胞生长及传代速度可观,活性良好,纯度较高。另外,肌腱干细胞的成功分离培养,也为肌腱相关疾病的研究开辟了一条新途径。

     

Plate selection for fixation of extra-articular distal humerus fractures: A biomechanical comparison of three different implants

Operative fixation of extra-articular distal humerus using a single posterolateral column plate has been described but the biomechanical properties or limits of this technique is undefined. The purpose of this study was to evaluate the mechanical properties of distal humerus fracture fixation using three standard fixation constructs.Two equal groups were created from forty sawbones humeri. Osteotomies were created at 80 mm or 50 mm from the tip of the trochlea. In the proximal osteotomy group, sawbones were fixed with an 8-hole 3.5 mm LCP or with a 6-hole posterolateral plate. In the distal group, sawbones were fixed with 9-hole medial and lateral 3.5 mm distal humerus plates and ten sawbones were fixed with a 6-hole posterolateral plate. Biomechanical testing was performed using a servohydraulic testing machine. Testing in extension as well as internal and external rotation was performed. Destructive testing was also performed with failure being defined as hardware pullout, sawbone failure or cortical contact at the osteotomy.In the proximal osteotomy group, the average bending stiffness and torsional stiffness was significantly greater with the posterolateral plate than with the 3.5 mm LCP. In the distal osteotomy group, the average bending stiffness and torsional stiffness was significantly greater with the posterolateral plate than the 3.5 mm LCP. In extension testing, the yield strength was significantly greater with the posterolateral plate in the proximal osteotomy specimens, and the dual plating construct in the distal osteotomy specimens. The yield strength of specimens in axial torsion was significantly greater with the posterolateral plate in the proximal osteotomy specimens, and the dual plating construct in the distal osteotomy specimens.Limited biomechanical data to support the use of a pre-contoured posterolateral distal humerus LCP for fixation of extra-articular distal humerus exists. We have found that this implant provided significantly greater bending stiffness, torsional stiffness, and yield strength than a single 3.5 mm LCP plate for osteotomies created 80 mm from the trochlea. At the more distal osteotomy, dual plating was biomechanically superior. Our results suggest that single posterolateral column fixation of extra-articular humerus fractures is appropriate for more proximal fractures but that dual plate fixation is superior for more distal fractures.     

肩关节后方不稳的诊疗现状

肩关节后方不稳发生率明显低于前方不稳,但是临床上诊疗难度大,误诊和漏诊率较高。其病因、临床表现治疗策略与前方不稳完全不同。因此,深入认识肩关节周围解剖结构、掌握检查方法、基于解剖和受伤方式对肩不稳进行分型对提高诊断准确率具有关键作用。CT三维重建对肱骨头及肩盂骨缺损的评估和核磁共振造影(magnetic resonance angiography,MRA)对于后方盂唇及关节囊病变评估有助于精确诊断。治疗方法分为保守治疗及手术治疗。对肌性不稳建议保守治疗。创伤性及发育不良性不稳建议手术治疗,具体根据肩盂侧或肱骨头侧损伤行不同术式。肩盂侧损伤根据骨缺损情况行软组织手术、植骨手术或截骨手术来重建后方稳定结构;肱骨头侧缺损则根据前方骨缺损面积行植骨术或肩胛下肌填塞术。手术方式有开放手术和关节镜手术,前者优势在于学习曲线短,固定牢固;后者优势在于微创操作及可以多角度观察病变部位并精确控制骨块位置。本文对将上述问题加以综述。     

组织工程关节软骨梯度仿生支架的研究进展

由于良好的机械性能和生物相容性,组织工程支架已经成为修复和再生关节软骨缺损的重要方法。随着组织工程技术的不断发展,过去十年已经开发和测试了许多支架的制备和形成方法,但是理想再生支架的制备一直存在争议。关节软骨作为人体关节内的承重组织,其基质结构和细胞组成呈带状,并且从软骨表层至软骨下骨存在着几个平滑的自然梯度,包括细胞...     

针对我国关节外科医生主治医师阶段手术相关数据的调查分析

目的 通过问卷调查的方式收集数据,分析我国关节外科医生选择假体和手术入路的影响因素以及关节置换辅助技术的使用情况等。方法 本研究采用电子表格调查问卷模式,调查人群设定为中青年关节外科副高及以上医师,使用Microsoft Excel软件对数据进行图表制作和统计分析。本次问卷调查由22个问题组成,包括当前国内关节外科医生毕业后主治医师阶段手术培训教育的环境和特点,每年初次和翻修全膝关节置换（total knee arthroplasty,TKA）以及全髋关节置换（total hip arthroplasty,THA）的病例数量,关节置换辅助技术的使用,手术方式和入路的选择,所使用关节假体的品牌,以及影响个人选择的因素。结果 问卷通过网络链接的方式发出,共回收完成312份问卷。其中56%的受访医生所在单位每年至少完成200例关节置换手术。43%的受访医生每年至少进行50例TKA,58%的受访医生每年至少进行50例THA。74.5%和65.9%的受访医生初次TKA和THA 90%以上的病例会选择同一个厂家的假体。主治医师阶段的经历、个人经验的积累、单位和厂家是关节外科医生选择TKA和THA假体和手术入路最主要的影响因素。59.0%的受访医生使用了关节置换辅助技术,其中40.8%认为辅助关节技术影响其关节假体的选择。结论 主治医师阶段的经历、个人经验的积累以及单位和厂家是国内关节外科医生选择假体和手术技术最主要的影响因素。     

关节镜治疗距下关节创伤性关节炎的临床疗效观察

目的探讨关节镜治疗距下关节创伤性关节炎的临床疗效。方法回顾分析 2011 年 1 月—2014 年 12 月收治并符合选择标准的 14 例距下关节创伤性关节炎患者临床资料。患者均为男性；年龄 32～62 岁，平均 42 岁。既往均为高处坠落伤致跟骨骨折；其中 8 例行石膏外固定，6 例行切开复位内固定术。受伤至该次手术时间 2～7 年，平均 3.4 年。采用关节镜下经外侧入路对距下关节进行清理和松解，术中探查关节软骨损伤并按照 Outerbridge 分级评价：3 级 4 例、4 级 10 例。手术前后采用疼痛视觉模拟评分（VSA）评价疼痛情况，美国矫形足踝协会（AOFAS）踝-后足评分评价踝关节功能恢复情况。结果术后切口均Ⅰ期愈合，无早期相关并发症发生。患者均获随访 18 个月。患者关节疼痛症状明显缓解，术后 18 个月 VAS 评分以及 AOFAS 踝-后足评分总分分别为（3.8±0.9）、（59.1±8.8）分，明显优于术前的（7.7±1.2）、（37.6±8.2）分，差异均有统计学意义（t=9.728，P=0.000；t=6.688，P=0.000）。随访期间无患者行距下关节融合，CT和MRI复查未见关节炎明显加重。 结论采用关节镜下清理治疗距下关节创伤性关节炎可以改善关节功能，延迟关节融合。     

Trochleoplasty for severe trochlear dysplasia significantly improves the quality of life of patients with symptomatic patellar instability

BackgroundTrochleoplasty is a recognized surgical technique to address severe trochlear dysplasia. The clinical and radiological outcomes of trochleoplasty surgery in trochlear dysplasia have been well reported. There is a paucity in literature regarding the correlation between trochleoplasty and quality of life (QoL). The aim of this study is to measure the improvement in QoL, in patients with severe trochlear dysplasia and recurrent patellar instability following trochleoplasty.MethodsBetween 2013 and 2019, 51 trochleoplasty cases were performed in 48 patients. They were identified from our prospectively kept database. All operations were performed by a fellowship trained consultant sports knee surgeon. Functional outcomes and QoL scores were assessed using Kujala, IKDC and EQ-5D index. Objective outcomes were obtained following each patient’s latest follow-up assessment.ResultsThe mean age at operation was 22y (SD ± 4.7, range 14–37y) and the mean follow-up period was 21.6 months (SD ± 15.2, range 12–60 months). The mean Kujala score improved from 58.1 (SD 14.9) to 77.9 (SD 17.3) at latest follow-up (p < 0.001). The mean IKDC score improved from 40.5 (SD 14.2) to 69.5 (SD 22.8) at latest follow up (p < 0.001). The mean EQ-5D index also improved from 0.593 (SD 0.257) to 0.824 (SD 0.189) at latest follow-up (p = 0.003). A higher Body Mass Index (BMI; >30 kg/m²) was associated with inferior outcomes.ConclusionTrochleoplasty is an effective surgical technique which improves the QoL in patients suffering from patellar instability secondary to severe trochlear dysplasia. BMI can be used to predict post-operative outcomes.