【作者】 郭智萍；

【导师】 张英泽；

【作者基本信息】 河北医科大学 ， 外科学， 2010， 博士

【摘要】 胫骨下1/3螺旋骨折合并后踝骨折是一种有规律性的复合骨折,损伤中后踝多为隐匿性骨折,在普通平片下常常不能显示骨折线,此类骨折漏诊率极高。各种影像学检查方法对胫骨下1/3螺旋形骨折合并后踝骨折的诊断具有重要价值,多层螺旋CT和MRI组织分辨率明显高于X线平片,对于后踝隐匿性骨折的检出率也明显提高,如何优化影像检查的方法,减少漏诊,是临床需要解决的一个重要问题。根据影像学表现对骨折进行分类和分型,了解后踝是否骨折及骨折块的详细信息,可以指导临床治疗。减少由于治疗不当引起的踝关节创伤性关节炎。本研究对胫骨下1/3螺旋骨折患者进行X线、CT及MRI检查,分析此类骨折的影像学特点,评价各种方法的诊断价值,为临床制定准确、恰当的治疗方案提供影像学基础。胫骨下1/3螺旋骨折合并后踝骨折往往发生于扭伤、摔伤等低能量的损伤中,关于其损伤机制仍然停留在假说阶段,相关的生物力学研究甚少。收集下肢标本进行生物力学研究,探讨其损伤机制,深入理解这种合并损伤,有助于提高骨折复位质量。胫骨下1/3螺旋骨折,往往同时合并后踝骨折,当后踝受累复位不良时,踝关节的功能恢复较差;在应用髓内钉或者接骨板固定胫骨干骨折时,如果内固定物置放不当,可能使未移位的后踝骨折块分离;在踝关节康复锻炼的过程中,后踝骨折亦可能分离移位;这时需行石膏固定或者二次手术固定,尽管如此,踝关节发生创伤性关节炎风险增高。因此,对胫骨下1/3螺旋形骨折患者,X线未能确诊是否有后踝骨折者,需行CT或MRI检查,根据检查结果,按损伤严重程度进行分型并制定手术方案,有助于提高该合并损伤的治疗效果。踝关节骨折是骨科的常见损伤,其中后踝骨折所占的比例高达25%。一般认为,单纯后踝骨折较少见,部分后踝骨折合并内踝、外踝、胫骨和腓骨(外踝以近部分)骨折。然而,目前较大样本的后踝骨折流行病学调查并不多见,为此,有必要对后踝骨折进行回顾性调查,以便了解后踝骨折的流行病学特点,提高后踝骨折诊治质量。第一部分胫骨下1/3螺旋骨折合并后踝骨折的影像分析目的:对胫骨下1/3螺旋骨折患者进行X线、CT及MRI检查,分析此类骨折的影像学特点,评价各种方法的诊断价值,为临床制定准确、恰当的治疗方案提供影像学基础。方法:对151例胫骨下1/3螺旋骨折进行了X线检查,对其中124例患者X线检查后踝为阴性者,在外伤后一周之内行多层螺旋CT扫描加重建及MR检查。多层螺旋CT重建层厚0.75mm,分别进行冠状面及矢状面重建。1影像学资料所有X线、螺旋CT、MR图像均由两位骨关节影像诊断医师阅读,并对每个图像的诊断结果达成一致意见。观察内容包括:1.1胫骨下1/3螺旋骨折线的形态,以及骨折线与后踝骨折的关系。后踝骨折线的形态,是否移位。1.2对于后踝隐匿性骨折的CT及MR图像:影像医师在仅知晓患者临床症状的情况下,判断隐匿性骨折是骨小梁骨折,还是骨皮质骨折。观察踝关节脱位情况,以及是否合并腓骨骨折及其他损伤。2后踝隐匿性骨折的诊断标准包括:多层螺旋CT上骨折的诊断标准为,贯穿正常的骨小梁的线形透亮影,边缘锐利,或骨皮质的不连续,或有骨折片的移位。若没有发现骨皮质骨折线,则认为是单纯骨小梁骨折。MR上骨折的标准为可以看到骨皮质骨折线,或骨小梁骨折线,或两者均有,骨折线区在STIR序列或T2WI序列应该表现为高信号。仅在STIR序列上出现的弥漫性高信号,被认为是骨髓水肿,不诊断为骨折。3统计学方法应用SPSS 13.0软件进行统计学分析。多层螺旋CT与MRI分别对于后踝骨小梁骨折和骨皮质骨折的显示能力的比较采用二项分布检验,p<0.05有统计学意义。结果:151例胫骨下1/3螺旋骨折的患者中,有126例(83.4%)发现合并后踝骨折,其中由多层螺旋CT和/或MR扫描发现后踝骨折有99例(78.6%)。1胫骨下1/3螺旋骨折合并后踝骨折的影像学分型:?根据胫骨骨折线与后踝骨折的关系将骨折分为A、B两型,A型:胫骨下1/3螺旋骨折合并单纯后踝骨折,两处骨折线无连续;B型:胫骨下1/3螺旋骨折线向胫骨远端延伸,累及后踝。根据后踝骨折的影像表现及合并损伤的程度分为3度。Ⅰ度:后踝骨折片小于25%,无分离错位的隐匿性骨折;Ⅱ度:后踝骨折片小于25%,骨折片分离错位者,或后踝骨折片大于25%者,患者不合并踝关节脱位和/或腓骨骨折;Ⅲ度:后踝骨折后踝骨折片大于25%的骨折,伴踝关节脱位和/或腓骨骨折者。在本组病例中A型损伤91例,B型损伤35例。在本组病例中Ⅰ度损伤患者59例,Ⅱ度损伤48例,Ⅲ度损伤19例。2后踝隐匿性骨折的检出在151例胫骨下1/3螺旋骨折患者的X线检查中,有27例检出合并有后踝骨折,X线诊断后踝骨折的敏感性为21.4%。对124例胫骨下1/3螺旋骨折X线平片未显示后踝骨折患者,行多层螺旋CT、MR扫描后发现99例后踝骨折,多层螺旋CT检出81例,MR检出99例。多层螺旋CT对于隐匿性后踝骨折敏感性为81.8%,特异性为100%,准确性为85.5%。MR对于隐匿性后踝骨折敏感性、特异性、准确性均为100%。在99例后踝隐匿性骨折中累及骨皮质的骨折78例(78.8%),其中多层螺旋CT检出78例,MR检出51例。对于后踝隐匿性骨折累及骨皮质的显示,多层螺旋CT敏感性、特异性、准确性均为100%;MR的敏感性为65.4%,特异性为100%,准确性为72.7%。对于后踝隐匿性骨折的显示MR敏感性高于多层螺旋CT,但无统计学意义(p>0.05)。对于后踝隐匿性骨折累及骨皮质的诊断,多层螺旋CT的敏感性明显高于MR(p<0.05)。结论:1.胫骨下1/3螺旋骨折合并后踝骨折发生率很高,占胫骨螺旋骨折的83.4%,后踝隐匿性骨折的发生率占78.6%。2. X线平片显示胫骨下1/3螺旋骨折合并后踝骨折仅有21.4%,因此对于X线片没有显示后踝骨折的胫骨下1/3螺旋骨折,应常规行多层螺旋CT或MR扫描。3.多层螺旋CT扫描后MPR成像,可提高对隐匿性骨折的检出率。多层螺旋CT和MRI在显示骨折细节上各有利弊,多层螺旋CT显示骨皮质骨折优于MR。MR显示骨折伴随的骨髓水肿敏感,可以作为诊断隐匿性骨折的金标准。第二部分胫骨下1/3螺旋骨折合并后踝骨折损伤机制的初步探讨目的:探讨胫骨下1/3螺旋骨折合并后踝骨折的损伤机制。方法:收集成人完整小腿标本23具,包括新鲜截肢标本15具,福尔马林浸泡的防腐小腿标本8具,经CT和MRI检查除外骨折。根据胫骨下1/3螺旋骨折合并后踝骨折患者的损伤机制,分别模拟小腿前倾踝关节中立位、小腿直立踝关节跖屈位、小腿直立踝关节背伸位以及小腿直立踝关节跖屈足旋前内翻位,应用自凝牙托粉将小腿标本固定于自制夹具,将夹具分别连接于NWS-10000扭转试验机、BOSE生物力学试验机和CSS-44020生物力学试验机。NWS-10000扭转试验机组给予外旋或内旋外力直至胫骨骨折,BOSE生物力学试验机组给予不同的垂直负荷同时施予50NM的旋转外力,CSS-44020生物力学试验机在给予垂直负荷的同时人为施予外旋作用力。试验结束后所用标本行CT、MRI检查,以观察有无胫骨骨折和/或后踝骨折。结果:在NWS-10000扭转试验机组,标本在旋转扭矩增加至72-107NM时胫骨发生骨折;本组标本在内旋作用力下胫骨下1/3发生骨折线自外下斜向内上的螺旋形骨折,在外旋作用力下胫骨下1/3发生骨折线自内下斜向外上的螺旋骨折,本组一具防腐小腿标本发生后踝骨折。在BOSE生物力学试验机组,标本分别固定于小腿前倾位踝关节中立位和小腿直立踝关节跖屈位,分别给予不同的垂直负荷同时施予50NM的外旋扭矩,本组仅1例固定于小腿前倾踝关节中立位的患者发生后踝骨折,其他标本未发生后踝骨折。本组标本均未发生胫骨干骨折,1例因轴向负荷过大导致胫骨远端粉碎骨折,其余各例发生踝关节半脱位或脱位。CSS-44020生物力学试验机组标本分别固定于小腿直立踝关节跖屈足内翻旋前位或足内翻旋后位,1例标本在施予近端夹具的外旋作用力下,发生踝关节脱位,2例标本在同时施予胫骨近端和远端旋转外力直接作用下发生胫骨干双处螺旋骨折,均未见后踝骨折。结论:本次生物力学实验证实了小腿近端在外旋暴力作用下会发生骨折线自内下至外上的胫骨下1/3螺旋骨折;本组试验分别在小腿直立踝关节跖屈位无垂直负荷的防腐标本和小腿前倾踝关节中立位垂直负荷下的标本模拟出后踝骨折,但是不易在其他标本上重复。第三部分胫骨下1/3螺旋骨折合并后踝骨折的临床分型及治疗目的:了解胫骨下1/3螺旋骨折合并后踝骨折的损伤特征,测量后踝骨折块的径线,对这种合并损伤进行分型,据此制定治疗方案并检验其治疗效果。方法:收集2007年7月至2009年6月我院诊治的胫骨下1/3螺旋骨折合并后踝骨折患者的临床资料,分别根据AO骨折分型、胫骨下1/3螺旋骨折合并后踝骨折分度进行统计。应用CT和MRI自带测量软件测量后踝骨折块的高度、宽度和长度,应用AUTOCAD2004软件测量后踝骨折块宽度占胫骨远端关节面长度的比例,并分析后踝骨折块不同径线之间的关系。根据胫骨下1/3螺旋骨折线与后踝骨折的关系将其分为A型损伤和B型损伤,B型损伤多合并胫骨远端关节面受累和踝关节其他部位损伤;据此制定手术方案指导其治疗,统计胫腓骨骨折和后踝骨折手术方式和使用的固定器械。术后定期随访进行影像学检查,根据可视化疼痛评估量表和美国足与踝关节协会踝与后足功能评分对其进行评价。结果:本组共126例患者,男性98例,女性28例,年龄39.9±16.7岁,左侧51例,右侧75例。其致伤机制以摔伤、扭伤和交通事故为主。后踝骨折经X线确诊27例,经CT确诊81例,经MRI确诊99例。根据AO骨折分型,42节段A型骨折104例,B型骨折21例,C型骨折1例;43节段骨折包括B型损伤119例和C型损伤7例。A型损伤91例,胫骨下1/3螺旋骨折合并单纯后踝骨折,两者为独立骨折。B型骨折35例,伴发损伤包括单纯胫骨远端关节面粉碎骨折2例,胫骨远端关节面单纯压缩骨折4例,胫骨远端关节面压缩粉碎骨折8例,踝关节半脱位9例,踝关节脱位3例,内踝骨折6例,外踝骨折3例等。本组患者112例腓骨骨折。测量显示后踝骨折块平均长度是9.9 mm(5.8-27.4mm),平均宽度是13.2mm (11.1-39.5mm),平均高度是28.5mm ( 9.6-48.3mm) ,后踝骨折占胫骨远端关节面的比例为0.36±0.14(0.07-0.61)。本组2例患者行手法复位和石膏固定,124例行手术治疗。A型损伤胫骨下1/3螺旋骨折患者1例行外固定,78例应用髓内钉固定,10例应用接骨板固定;后踝骨折应用钢板固定1例,克氏针固定6例,空心螺钉固定11例,拉力螺钉固定17例;B型骨折患者中,胫骨下1/3螺旋骨折外固定架固定2例,接骨板固定33例;后踝骨折接骨板固定4例,拉力螺钉固定24例。术中后踝无移位或劈裂。术后随访,胫骨下1/3螺旋骨折25例3个月、83例患者6个月,15例患者9个月达到了骨折愈合标准,3例患者胫骨下1/3螺旋骨折不愈合,2例应用石膏固定的胫骨下1/3螺旋骨折畸形愈合;后踝骨折107例3个月、29例6个月骨折月骨折愈合。患者12个月89例患者获得随访,行VAS评分,骨折部位疼痛得分为0.1±1.1(0-4);主动活动时疼痛得分为0.2±1.5(0-5);负重行走时疼痛得分为0.5±1.1(0-7);行美国足与踝关节协会踝与后足功能评分,得分86.7±9.6(58-98)。结论:本研究分析了我院胫骨下1/3螺旋骨折合并后踝骨折的损伤特点,根据胫骨骨折线是否直接累及后踝将其分为A型损伤和B型损伤,A型损伤占多数,B型损伤多伴有胫骨远端关节面压缩塌陷骨折和踝关节其他部位骨折。根据分型指导治疗,患者骨折愈合率高,踝关节功能恢复满意。第四部分566例后踝骨折的流行病学分析目的:回顾性分析2007年1月至2009年12月在河北省骨科医院诊治的后踝骨折患者的流行病学特点。方法:利用图片存档及通信系统(picture archiving and communication system,PACS)及病案查询系统,整理并分析我院2007年1月～2009年12月3年间诊治的后踝骨折患者X线片以及病历等资料,统计其性别、年龄、损伤部位、伴发的内踝骨折、外踝骨折以及胫腓骨骨折部位等特点,并进行分析。结果:本次回顾性研究共调查我院3年间后踝骨折患者566例,具有如下特点:男性多于女性,男性患者的高发年龄为31～40岁;女性患者的高发年龄为51～60岁;左侧多于右侧,双侧最少;单纯后踝骨折少,仅59例(10.42%);507例(89.58%)伴发其他部位骨折,其中伴同侧腓骨骨折最为多见,其他常见伴发骨折脱位依次为内踝骨折、外踝骨折、胫骨骨折、踝关节半脱位和脱位、距骨和跟骨骨折以及前踝和跖骨骨折。本组294例后踝骨折同时合并胫骨和/或腓骨骨折,其中154例合并腓骨骨折,85例同时合并胫腓骨折,仅合并胫骨骨折者最少,只有55例。单纯后踝骨折中,同时合并胫腓骨骨折最为常见;后踝骨折合并内踝骨折患者中,伴发腓骨骨折最为常见;后踝骨折合并外踝骨折的患者中,伴发胫骨骨折最为常见。致伤原因以摔伤、扭伤等低能量损伤为主。本组住院患者467例,其中男性298例,女性169例,平均年龄40.1岁;致伤原因以扭伤、交通事故和摔伤为主;18名患者伴发软组织、血管、神经等损伤。住院患者中行切开复位内固定为主。结论:本次调查揭示了我院3年间诊治后踝骨折的流行病学特点,有助于提高对后踝骨折严重性和复杂性的认识。更多还原

【Abstract】 Spiral fracture of low 1/3 tibia shaft combined with posterior malleolar fracture was a special complicated fracture. The posterior malleolar fracture usually present as occult fracture, which was negative in X-ray examination. So the rate of missed diagnosis was very high. The spatial resolution of MSCT and MR were higher than X-ray and they served as tools to detect posterior malleolar occult fracture. How to select imaging method to increase diagnosis accuracy was an important problem in clinic. Determining type and scale of fracture according to images could provide more detail information of fracture fragment, and reduce traumatic osteoarthritis that induced by inappropriate treatment. This study evaluated the imaging features and diagnosis value of tibia diaphyseal fracture in X-ray, CT and MRI, and provide imaging basis for clinical treatment.Spiral fracture of low 1/3 tibial shaft is often associated with posterior malleolar fracture, which is a special kind of combined injury. This combined injury often occurs in the sprain, a fall or other low-energy trauma. Its injury mechanism remains a hypothesis and there are only a few related biomechanical studis. Performing biomechanical study and exploring its injury mechanism with the use of specimens of lower extremities is helpful in understanding profoundly this combined injury and improving the quality of fracture reduction. Spiral fractures of distal third of the tibia are often associated with posterior malleolar fracture. When the posterior malleolar fractures occure, the functional reconvery of ankle joint will be poor. In some fractures, besides posterior malleolar fractures, other part of ankle joint may also involved in fractures, or comminuted or compressed distal tibial articular fractures may occure, which call for great attention in the management of such fractures. In the management of the spiral fractures of distal third of the tibia using intramedullary nail or plate, if the implant placed unproperly, it could make the non-displaced posteriror malleolar fracture displaced. In the rehabilitation exercises of the ankle joints, the unfixed posterior malleolar fractures may also become displaced. In such condision, conservative or operative fixation should be performed and even so, the ankle joint is an increased risk to sustain posttraumatic arthritis. Therefore, CT or MRI tests shohld be recommended in tibial spiral fractures where posterior malleolar fractures can’t be diagnosed by X ray test. Classifying such combined injuries and making surgical plan based upon the severity of posterior malleolar is helpful to improve the outcome.Ankle fractures are common in orthopedic practice, among which as high as 25% are posterior malleolar fractures. It is generally believed that simple posterior fracture is a rare injury. The posterior malleolar fractures are often aossociated with medial malleolar fractures, lateral malleolar fractures as well as tibial and fibular fractures (proximal to lateral malleolar fractures). However, the large-sample epidemiological survey of posterior malleolar fractures ankle fractures is rare. Therefore it is necessary to conduct retrospectively epidemiological study on posterior malleolar fractures to in order to reveal its epidemiological characteristics and improve the treatment of posterior malleolar fractures. Part 1 Imaging Analysis of spiral fractures of distal third of the tibia Fracture with Posterior Malleolar FractureObjective: To evaluate the imaging features and diagnosis value of tibia diaphyseal fracture in X-ray, CT and MRI, and to provide the imaging basis for clinical treatment.Methods: One hundred and fifty-one patients with tibia spiral fracture were performed X-ray examination. 124 patients (98 male, 28 female; age range, 12–80 years; mean age, 39.9±16.7 years) with negative X-ray results underwent MSCT and MR imaging within a week after trauma. MSCT data were obtained with 0.7-mm-thick multiplanar reformations were performed in transverse, coronal, and sagittal planes relative to the tibia. 11 Imaging dataImages of X-ray, MSCT and MR were reviewed by two musculoskeletal radiologists in consensus. The contents including:1.1 The shape of tibia fracture and posterior malleolar fracture, and the relationship between them. Displace of the fracture was recorded. The size of fracture block of posterior malleolus was measured and its proportion to malleolus was calculated at axial CT images.1.2 MSCT and MR images were reviewed. To approximate the clinical situation, the readers were informed about the site of clinical symptoms. The readers distinguished between signs of a cortical and signs of a trabecular fracture. In addition, readers were asked to note any other signs, such as dislocation of ankle joint or fibula fracture.2 Criteria for occult posterior malleolar fracture:Criteria on MSCT images were the presence of a sharp lucent line within the trabecular bone pattern, a break in the continuity of the cortex, a sharp step in the cortex, or a dislocation of bone fragments.Criteria for a bone fracture on MR images included the presence of a cortical fracture line, a trabecular fracture line, or a combination of both. Such a fracture line had to be hyperintense on STIR and T2-weighted images and hypointense or hyperintense on T1-weighted images. Evidence of a zone of diffusely increased signal intensity on STIR images was interpreted as bone marrow edema but not as a manifest fracture.3 Statistical AnalysisData were analyzed with a statistical software package (SPSS 13.0). A binomial test was used to evaluate the significance of the differences between MR imaging and MSCT with regard to the detection of posterior malleolar fractures and cortical involvement at a P value of less than 0.5. Results: 126 (83.4%) in 151 tibia shaft fracture were found associated with posterior malleolar fracture. 99 (78.6%) posterior malleolar occult fracture were detected by MSCT and/or MRI.1 Imaging typing of tibia spiral fracture fracture combined with posterior malleolar occult fracture.Type A and type B were determined according to the association of tibia fracture and posterior malleolar fracture. Type A indicated fracture of tibia shaft and fracture of posterior malleolar were separate. Type B indicated that these two fractures were continued.Three scales were determined according to imaging features. Scale 1: Posterior malleolar fracture fragment was less than 25%, and no displacement occult fracture. Scale 2: Posterior malleolar fracture fragment was less than 25% with displacement, or posterior malleolar fracture fragment was larger than 25%. no ankle joint dislocation and/or fibula fracture was combined in this kind of patients. Scale 3: Posterior malleolar fracture fragment was larger than 25%, combined with ankle joint dislocation and/or fibula fracture. 91 cases in type A and 35 cases in type B were found. 59 cases in Scale 1, 48 cases in scale 2, 19 cases in scale 3 were determined.2 Detection of posterior malleolar occult fracture124 cases whose X-ray were negative were performed MSCT and MR examination. 99 cases among them were found posterior malleolar fracture. 78 cases (78.8%) involved cortex. 81 cases were detected by MSCT, while 99 were detected by MRI. The sensitivity of posterior malleolar occult fracture in MSCT was 81.8%, specificity was 100%, and accuracy was 85.5%. MRI resulted in 100% sensitivity, specificity and accuracy. For 78 cases with posterior malleolar occult fracture involved cortex, 78 cases cortex fracture were detected by MSCT, 51 cases by MRI. The sensitivity, specificity and accuracy in CT were 100%. The sensitivity of detection of cortex fracture in MRI was 65.4%, specificity was 100%, and accuracy was 72.7%.The sensitivity of posterior malleolar occult fracture in MR was higher than MSCT, however with no statistic significant.The sensitivity of cortex fracture in MSCT was significant higher than MR (p<0.05).Conclusion: 1. Tibia shaft fracture was often associated with posterior malleolar fracture with 83.4%. The incidence rate of posterior malleolar occult fracture was 78.6%.2. Only 19.8% posterior malleolar fracture combined with tibia shaft fracture was detect by X-ray. For tibia shaft fracture patients, even no posterior malleolar fracture was found by X-ray, MSCT or MR should be performed.3. MPR of MSCT can improve detection of occult fracture. MSCT has advantage in detecting cortex fracture, and discriminate pure trabecular fracture or cortex fracture, which was helpful for clinical treatment and prognosis. MR is sensitive in detecting bone marrow edema lesion combined with fracture.Part 2 Investigation of the injury mechanism of spiral fractures of distal third of the tibia with associated posterior malleolar fractureObjective: To investigate the injury mechanism of spiral fractures of distal third of the tibia with associated posterior malleolar fracture.Methods: 23 specimens of adult cnemis were collected, including 15 fresh amputated lower extremity and 8 antiseptic specimens soaked in formalin. Fracture of each specimen was excluded by CT and MRI scan. On the basis of the injury mechanism of spiral distal third tibial with associated posterior malleolar fracture, The specimens were fixed in the fixture using the self-curing denture acrylic to simulate the lower extremity in anteversion position and the ankle joint in neutral position, the lower extremity in upright position and ankle joint in plantar flexion position, the lower extremity in upright position and ankle joint in dorsal flexion position, and the lower extremity in upright position and ankle joint in plantar flexion position with the foot in pronate and varus position. The fixture was separately connected to the NWS-10000 torsion testing machine, BOSE biomechanical testing machine and CSS-44020 bio-mechanical testing machine. The NWS-10000 torsion testing machine offered external rotation or internal rotation forces until tibia fractured. The BOSE biomechanical testing machine provided different vertical loads and 50NM torquemoment at the same time. The CSS-44020 biomechanical testing machine provided vertical loads with rotation forces offered artificially. After the test, the specimens were scanned by CT and MRI to examine whether the spiral fractures of distal third of the tibia with associated posterior malleolar fracture occured.Results: In the specimens tested on the NWS-10000 torsion testing machine, tibial fractures occurred when the rotating torquemoment increases to 72-107NM. Under internal-rotation torquemoment, the spiral fractures of distal third of the tibia run from lareral-inferior to medial-superior. Under external-rotation torquemoment, the spiral fractures of distal third of the tibia run from medial-inferior to lateral-superior and one corrosion specimen sustained posterior malleolar fracture simultaneously. In the specimens tested on the BOSE biomechanical testing machine, specimens were separately fixed simulating the lower extremity in anteversion position and the ankle joint in neutral position or the lower extremity in upright position and ankle joint in plantar flexion position. The specimens were offered vertical load and 50NM rotation torquemoment simultaneously. In this group, no spiral fractures of distal tibia occurred. One specimen sustained comminuted distal tibial fracture due to violent vertical load and the other specimens sustained subluxation or dislocation of ankle joints. In the group tested on the the CSS-44020 biomechanical testing machine, specimens were separately fixed to simulate the lower extremity in upright position and ankle joint in plantar flexion position with the foot in pronated- or supine- varus position. Ankle dislocation was found in a specimen when the external rotation force acts on the proximal cnemis. Dual spiral tibial fractures were noted in 2 specimens when the rotating force acts directly on both proximal and distal ends of the tibia. But no posterior malleolar fracture occurs.Conclusions: The biomechanical study verified that spiral fractures of distal third of the tibia can occur when the external rotation force acts on the proximal cnemis and the fracture line is from medial-inferior to lateral-superior. Posterior malleolar fracture were noted in 2 specimens, one corrosion specimen in upright position and ankle joint in plantar flexion position without vertical load and one fresh specimen in anteversion position and the ankle joint in neutral position under vertical load. However, this can’t be reproduced in other specimens.Part 3 The clinical classification and treatment of spiral fractures of distal third of the tibia with associated posterior malleolar fractures.Objective: This study aims to investigate the injury characteristics of spiral fractures of distal third of the tibia with associated postwrior malleolar fractures, to measure the measurement the posterior malleolar fracture fragment, to classify the combined injury and study the efficacy of the surgical plan based upon the new injury classification.Methods: From July 2007 to June 2009 the data of tibial shaft fractures with associated posterior malleolar fractures were collected in our hospitl, which were analysed according to AO classification of fracture type and the new classificaiton referencing the severity of posterior malleolar fractures. The height, width and length of the fragment of posterior malleolar fracture were measured with the application of measurement software in CT and MRI. The ratio between the width of the posterior malleolar fragment and the width of the distal tibial articular surface were measured in the lateral radiograph and saggital CT or MRI images using the AUTOCAD2004. The relationship between the width, length and height of the fragment of posterior malleolar fracture were analysed. The combined injury can be classified into type A and type B injury referencing whether tibial shaft fracture runs directly to the posterior malleolus. Type B injury is often combined with distal tibial comminuted or compressed articular fractures and fractures of other parts of the ankle joint. Referencing the new classification, surgical plans were made to guide the management of the combined injury. The implants and surgeries applied in the treatment of tibial and fibular fractures with associated posterior malleolar fracutres were recorded and analysed. At regular postoperative follow-ups, radiological examinations were carried out and the funcional recovery of ankle joint were eveluated with the use of visual analogue score(VAS) and AOFAS Ankle-Hindfoot Scale.Results: There were 126 patients including 98 males and 28 female with the age of 39.9±16.7 years old in the study. There were 51 left and 75 right fractures. The majority of the patients were injured in falls, sprains or traffic accidents. 27 posterior malleolar fractures were diagnosed with radiograph, 82 with CT scans and 17 with MRI scans. The fracture pattern includes 17 gradeⅠinjuries, 82 gradeⅡinjuries, 19 gradeⅢinjuries and 8 gradeⅣinjuries. According to AO classification of fracture, the group consists of 104 cases of 42-type A fractures, 21 cases of 42-type B fractures and 1 cases of 42-type C fractures. The group included 119 cases of 43-type B fractures and 7 cases of 43-type C fractures. On the basis of the new classificaiton of the combined injuries, there were 91 cases of type A injuries, in which tibial shaft fractures and the posterior malleolar fracture were two separate fractures, and 35 cases of type B injuries. In type B injuries, besides posterior malleolar fractures, there were 2 distal tibial articular comminuted fractures, 4 distal tibial articular compressed fractures and 8 distal tibial articular comminuted-compressed fractures, 9 cases of ankle dislocation, 3 cases of subluxation of ankle joint, 6 medial malleolar fracture and 3 lateral malleolar fractures. There wre also 112 fibular fractures in the group. The measurements demonstrated that the average length of posterior malleolar fracture was 9.9 mm(range, 5.8-27.4mm), the average width was 13.2mm(range, 11.1 -39.5mm) and average height was 28.5mm (9.6-48.3mm). The ratio between the width of the posterior malleolar fracture and the distal tibial articular surface was 0.36±0.14(0.07-0.61). Manipulative reduction and cast immobilization were performed in two patients and surgeries were carried out in the other 124 patients. Among type A injuries, one tibial shaft fracture was treated with external fixators, 78 with intramedullary nailing and and 10 with plate fixation; one posterior malleolar fractures were managed with plate, 6 with Kirschner wires, 11 with cannulated screws, 17 with lag screws. Among type B injuries, 2 tibial shaft fractures were fixed with external fixators and 33 with plates; 4 posterior malleolar fractures were managed with plates and 24 with lag screws. 89 patients were followed up at 12 months postoperatively. The VAS score on fracture pain was 0.1±1.1 (range, 0-4). The VAS score on active pain of the ankle joint was 0.2±1.5 (range, 0-5) and that on weight-bearing walking pain was 0.5±1.1 (range, 0-7). The AOFAS Ankle-Hindfoot Scale was 86.7±9.6 (range, 58-98).Conclusion: This study revealed the injury features of tibial shaft fracture with associated posterior malleolar fractures of our hospital. The combined injury can be classified into type A and type B injury referencing whether tibial shaft fracture runs directly to the posterior malleolus. Type B injury is often combined with distal tibial comminuted or compressed articular fractures and fractures of other parts of the ankle joint. The new classification can be used to guide the management of the combined injury with high union rate of the fractures and satisfactory functional recovery of ankle joint.Part 4 The epidemiological analysis of posterior malleolar fracture in Hebei Orthopedic HospitalObjective: To investigate the epidemiological features of patients with posterior malleolar fracture treated in our hospital between January 2007 and December 2009.Methods: The data of patients with posterior malleolar fracture treated in our hospital from January 2007 to December 2009 are collected through the PACS system and case reports checking system and analyzed. The issues include gender, age, injuried sites, the features of the combined medial malleolar fractures, lateral malleolar fractures, tibial fractures and fibular fractures.Results: 566 patients with posterior malleolar fracture treated in our hospital during three years were included in the retrospective study. There are more men than wonem in the group. The men aged 31-40 years old are at high risk to sustain this fracture and the women aged 51-60 years old are at high risk. The left fractures is more than the right ones and bilateral fractures are the least. There are 59 cases with simple posterior malleolar fractures and 507 patients who sustaine other combined injuries. Among the 507 cases, the ipsilateral fibular fractures were the most common and other combined fractures or dislocations are medial malleolar fractures, lateral malleolar fractures, tibial fractures, dislocations of the ankle joint, talar fractures, calcaneal fractures, anterior malleolar fractures and metatarsal fractures. 294 cases with posterior malleolar fractures are with associated tibial or fibular fractures, including 154 tibial fractures, 85 tibial-fibula fractures and 55 fibular fractures. The simple posterior malleolar fractures are often combined with tibial-fibular fractures. The posterior and medial malleolus fractures are often combined with fibular fractures. The posterior and lateral malleolus fractures are often combined with tibial fractures. Low-energy trauma such as fall and sprain is the major cause of injury. 467 patients were admitted to our hospital including 298 males and 169 females with an average age of 40.1 years old. The major causes of injury are sprains, traffic accidents and falls. 18 patients combined with injuries of soft tissue, blood vessels and nerves. Open reduction and internal fixation is the main treatment algorism.Conclusion: This investigation revealed the epidemiological features of posterior malleolar fractures of our hospital which will help to understand the seriousness and complexity of the posterior malleolar fractures.更多还原