【作者】 侯致典；

【导师】 钟世镇； 王增涛；

【作者基本信息】 南方医科大学 ， 人体解剖与组织胚胎学， 2013， 博士

【摘要】 研究背景：手不仅是人的劳动器官也重要的感觉器官,同时还是人的第二张脸。是人们日常生活学习、劳动不可或缺的重要器官。日常工作中由于劳动保护的不足,手部损伤十分常见,如何更好的修复手部创伤,恢复手的功能一直是骨科、手外科、显微外科医生不断探索的课题。足部组织与手部组织有很大的相似性：如足背的皮肤浅筋膜薄而疏松、血管分布比较丰富、皮肤颜色外形等都同手部皮肤相接近；足部骨关节、伸屈肌腱、血管、神经等组织都同手部相应组织在结构和功能上相似,因此临床常用足部皮肤、骨关节、神经、肌腱等组织来修复手部组织的缺损,以重建手的功能。近年来随着显微外科技术的不断发展,越来越多的学者采用显微外科方法应用足部组织作为手修复和重建的供区,使得手部组织缺损的修复不断完善,同时不断探索尽可能提高手术的安全性并减少对供区的创伤。特别是在拇手指再造方面,自从1966年杨东岳开展了游离第2足趾再造拇指及1980年Morrison报道的拇甲瓣修复拇指以来,该类术式在临床应用广泛越来越广泛。目前,临床上最常用的手术方式还是以全部或者部分足部组织移植或者组合移植来再造手指。另外,临床中常用的第1跖背动脉皮瓣、趾蹼皮瓣、拇趾腓侧皮瓣、第2趾胫侧皮瓣、带伸肌腱的足背皮瓣等组织瓣移植都多以第1跖背动脉或者足背动脉为蒂。术中对第1跖背动脉的识别、游离、保护和切取是手术成功的关键,因此准确判断第1跖背动脉的来源、走行、分支分布对于手术成败至关重要。然而,第1跖背动脉变异较大,走行及口径不恒定,国内外不少学者对第1跖背动脉的解剖进行了一系列的研究,根据解剖和临床资料提出了几种不同的分型方法和分型数据。在众多的分型法中,以Gilbert分型法临床应用最为广泛。1976年Gillbert解剖50支红色乳胶灌注的足部标本,研究了第一趾蹼区域的解剖结构：根据第1跖背动脉和第1骨间背侧肌的相互关系将第1跖背动脉分成三型。在该研究中发现,占主要比例的是第1跖背动脉位于第1骨间背侧肌表面或者位于肌肉内部。另外有22%的标本中血管为于肌肉的下方。在12%的标本中,第1跖背动脉细小或者缺如。1983年Leung报道了他对第一趾蹼相关解剖的研究成果,他将第1跖背动脉分成7型。他的分型不仅包含了第1跖背动脉,也包含第1跖底动脉和足背动脉的相关变异。May和Lee也曾经报道了对第1跖背动脉的不同分型方法。Lee在1997对第1跖背和跖底动脉的起源和相互吻合做了研究,他将其分成2组。May将第1跖背和第1跖底动脉之间的吻合分成了三种类型。1.第1跖背汇入第1跖底的分支点。2.第1跖背动脉同第1趾底吻合3.第1跖背动脉同第2趾底吻合。自1998年12月至2010年12月,我们进行了近600个手指的全形再造和48例新鲜标本解剖。通过临床和标本解剖等研究我们发现,第1跖背动脉的解剖同Gilbert等学者的描述不相一致。第1跖背动脉的分型,使医生对第1跖背动脉的解剖有了更清楚的认识,推动了第2足趾移植、拇趾甲皮瓣等相关手术的开展与普及。但以往文献中对第1跖背动脉的分型的描述,都提及第1跖背动脉从第1骨间背侧肌中间穿行这一类型,并且在不少作者的分型中,都描述这类型是比例最高的。有的作者还将第1跖背动脉肌内型进一步分为几种亚型。第1跖背动脉肌内型的患者,手术时需切开第1骨间背侧肌,将第1跖背动脉从第1骨间肌中解剖游离出来或者将第1骨间背侧肌携带在第1跖背动脉上,一起游离出来。解剖游离肌内型第1跖背动脉是手术中最难的操作部分,并且会对第1骨间背侧肌造成不同程度的损伤,由此带来一些不良影响：影响第2足趾的功能、在受到破坏的第1骨间背侧肌表面植皮不易成活等。这种类型的第1跖背动脉在以往的文献中报道比例最高。我们在临床手术和标本解剖时发现,第1跖背动脉绝大多数都是位于第1骨间背侧肌和第1跖骨体的间隙内,没有发现有穿行过肌肉内部的类型。而第1跖背动脉是否穿行肌肉,对手术方式有较大的区别,并且手术效果存在根本的不同,因此本课题希望近一步探讨第1跖背动脉在走行过程中的解剖特点,特别是其同第1骨间背侧肌的位置关系。并根据解剖特征提出新的第1跖背动脉临床分型,针对不同的解剖类型,临床采用不同的手术方式,以更简便安全的解剖游离第1跖背动脉。材料与方法解剖标本选取24例,48侧红色乳胶灌注成人新鲜足部标本,所有标本来自南方医科大学临床解剖学研究所(广州中国)和山东省临床医学研究院修复重建研究所。所有足部标本从踝关节离断,经胫前或者胫后动脉灌注生理盐水,直到回流盐水澄清。然后注入约25m1红色乳胶并置入-30度冰箱。解剖足部第1、2趾,使用游标卡尺测量并记录第1跖背动脉的起源、起始处直径；第1跖背动脉同第1骨间背侧肌的位置关系；以及同第1跖底动脉吻合支的直径。由于第1跖背动脉同跖底动脉间吻合支过于细小时,其临床应用受到限制,因此我们将直径小于0.5mm的吻合支归入细小或者缺如型。本研究观察了30例足部铸型标本。所有标本注入20m1乙酸乙酯充盈微细血管,应用过氯乙烯和牙托材料的混合填充剂制作铸型标本.其中5例使用碱液去除软组织,保留骨骼。仔细观察第1跖背动脉的起始及其与第1跖底动脉的吻合关系。本组临床病例共148例,男116例,女32例；年龄在5-58岁,平均33.5岁。临床病例选取需要术中解剖游离第1跖背动脉的手术病例如：第2足趾移植,拇甲瓣、拇指腓侧皮瓣游离移植等。所有选取病例均完整观察并记录了第1跖背动脉来源、在第1、2跖骨间隙的走行及分支分布。5例健康成人志愿者进行了足部CT血管造影和三维重建。通过上臂头静脉注入碘海醇造影剂,然后采用螺旋CT扫描(GE Discovery CT750HD)。采用GE ADW4.4工作站对扫描数据进行容积重现、多平面重建和曲面重建技术,并对相关图片赋予伪彩显示。170例正常成人(男性98人,女性72人,15-60岁,平均37.5岁),340侧足进行彩色多普勒超声检查,观察记录第1跖背动脉的起源、同第1骨间背侧肌的解剖关系以及血管的直径。结果第1跖背动脉主要来源于足背动脉起始处直径1.48±0.20mm.在近端血管绕过第1骨间背侧肌胫侧起点后,在第1、2跖骨间隙向远端走行。在远端血管通过跖骨深横韧带的背侧浅出后,分出两条细小的趾背动脉,分别营养拇趾和第2趾的背侧相对缘的皮肤,其远端的终末支常与第1跖底动脉吻合,吻合后发出2条趾底动脉：拇趾腓侧趾底动脉和第2趾胫侧趾底动脉营养拇趾和第2趾。第1跖背动脉变异较大,主要表现在第1跖背动脉在走行过程中同第1骨间背侧肌的位置关系以及末端同跖底动脉的吻合上。足部第1骨间背侧肌解剖足部第1骨间背侧肌为双羽肌,起点由第1跖骨体发出的胫侧头和第2跖骨体发出的腓侧头组成,两头相合经跖骨深横韧带背侧,止于第2趾近节趾骨底两侧和趾背腱膜。胫侧头、腓侧头的起点分别位于第1、2跖骨体的近端,胫侧头在第1跖骨体上的附着处长度约为腓侧头的1/5,在跖骨间隙中形成一个连接第1跖骨和第1骨间背侧肌之间的腱弓样结构。第1跖背动脉同第1骨间背侧肌的解剖关系本研究显示第1跖背动脉在第1、2跖骨间隙同第1骨间肌的解剖关系主要有两种：1.血管走行位于第1骨间背侧肌的表面,其走行过程中位置表浅.此种类型中第1跖背动脉起自足背动脉或者足底深支,可以为足背动脉的直接延续,也可以在胫腓侧头之间由足底深支发出后浅行至骨间背侧肌背侧.然后第1跖背动脉在跖趾关节处发出跖背动脉,向远端走行在骨间背侧肌与足背浅筋膜之间,走行在跖骨深横韧带的背侧,终末支常与跖底动脉吻合。2.血管位于第1骨间背侧肌和第1跖骨体的间隙内。本研究多数样本显示第1跖背动脉由足背动脉发出后在第1骨间背侧肌胫、腓侧头之间,两头的交汇处绕过第1骨间背侧肌胫侧头所形成的腱弓向下内方走行穿入至第1骨间背侧肌和第1跖骨体之间,然后走行逐渐偏向胫侧.在第1骨间背侧肌和第1跖骨体之间的间隙内走行,走行过程中紧贴第1跖骨体。血管远端1/3逐渐向跖侧浅出,在跖骨深横韧带的背侧向远端走行。走行过程中发出肌支营养第1骨间背侧肌,肌支直径远小于第1跖背动脉。这种类型约占所有类型的84.29%。铸型标本清晰显示了第1跖背动脉的血管解剖类型,可以清楚的观察到第1跖背动脉的起源及其与第1跖底动脉动脉的吻合。约16.67%的铸型标本中,第1跖背动脉在足背动脉发出足底深支处或者发出前,由足背动脉发出,最常见的是约70.00%的铸型标本中第1跖背动脉起自足底深支。约6.67%的第1跖背动脉起自足底深弓,或者同第1跖底动脉动脉共干起自足底深弓。第1跖背动脉同第1跖底动脉的最常见的吻合类型是：第1跖背动脉远端走向趾蹼处,向跖侧走行与第1跖底动脉直接吻合,两条血管吻合后再发出两条趾底动脉,约83.33%的铸型标本是这种类型。在约13.33%的铸型标本中,第1跖背动脉同第1跖底动脉没有吻合或者吻合支细小(小于0.5mm)。第1跖背动脉和第1跖底动脉单独发出一支血管分别营养拇趾腓侧和第2趾胫侧。在新鲜标本和手术中也发现了这种吻合类型。在所有的铸型标本中发现1例标本,第1跖背动脉与第1跖底动脉之间没有吻合,第1跖背动脉单独发出2支趾背动脉,第1跖底动脉单独发出2条趾底动脉。彩色多普勒超声检查可以实时显示血流情况,并且该血管检查安全非侵入、无创伤。因此本研究使用彩色多普勒超声对足背和第1跖背动脉进行了连续解剖学观察。所有检查中均清晰显示了第1、2跖骨、第1跖背动脉和第1骨间背侧肌的位置关系。在340个样本中,占绝对大多数比例的第1跖背动脉起自足背动脉。约有84.12%的第1跖背动脉位于第1骨间背侧肌和第1跖骨之间的间隙内,而不是血管穿过肌肉中间。约11.76%的样本中第1跖背动脉位于第1骨间背侧肌的表面,如图11矢状面所示。约有4.12%的样本中第1跖背动脉缺如,或者血管非常细小(小于0.5mm)。CT血管造影可以很好的显示出1、2趾的血供。在连续的CT冠状位片上叶可以清晰显示出第1跖背动脉和第1骨间背侧肌的位置关系。在曲面重建图和3D图形中可以很好的显示出血管和肌肉的形态。大部分样本中血管都是走行于骨间背侧肌和跖骨之间的间隙内,他们之间的界线非常清晰。小部分样本显示血管走行于肌肉的表面。临床和解剖中发现约有8.16%(16/196)的标本显示在第1、2跖骨间隙,第1骨间背侧肌表面同时存在着伴随第1跖背动脉由足背动脉发出的一个细小分支,称为副第1跖背动脉。副第1跖背动脉多同第1跖背动脉一起发自足背动脉,血管常走行于肌肉表面。或者末端分布到拇趾和第2趾的趾背相对缘。大多数副第1跖背动脉血管都较细小(直径小于0.5mm),约1%的样本血管直径同第1跖背动脉类似。临床手术和解剖中发现部分标本第1跖背动脉直径非常细小,甚至在显微镜下解剖也没能发现确切的第1跖背动脉,考虑为血管纤细或者血管缺如。该部分样本同Gilbert所描述的Ⅲ型类似,约占2.85%。手术病例及标本解剖中均未发现第1跖背动脉走行在肌肉内部或者在第1骨间背侧肌肌肉下方的情况,这同Gilbert及其他文献中报道的不一致。以往分型中其肌肉内部型、肌肉下占很大比例,这与本研究发现有很大的区别。而是否存在肌内型对临床手术有很大的影响。血管在肌肉和跖骨间隙内时,仅需要切断肌肉的胫侧头就可以清晰显露跖背动脉,第一跖背动脉的解剖游离简便安全。手术时需要切开第一骨间背侧肌,在肌肉中解剖寻找第一跖背动脉。这样做,一方面手术难度大,另一方面对受区损伤太大。因此深入研究第1跖背动脉的解剖特点,探讨是否存在肌内型,以及血管同肌肉之间的位置关系类型,对临床手术具有重要的价值。临床手术中游离第1跖背动脉不是为了做血管的移植,而是为了以第1跖背动脉为蒂,作为供血动脉进行组织的转位或者游离移植,所以临床手术中需要考虑血管的来源和供养的部位即血管的终末分支。为了更好的描述第1跖背动脉的解剖类型,按照第1跖背动脉的血管来源、走行和分支分布作为第1跖背动脉分型的关键点。ABC分型方法：以第1跖背动脉的起源(Arise)、在趾蹼处的分支(Branch)吻合和在第1跖骨间隙的走行(Course)作为分型的关键点,根据第1跖背动脉在三个关键点的不同解剖情况分别统计。按照第1跖背动脉的起源(Arise)’情况分为3型：(1)足背动脉型：第1跖背动脉起源于足背动脉,为足背动脉的直接延续或源于足底深支,记作A1。(2)足底型：第1跖背动脉起自足底深弓或与第1跖底动脉共干由足底深弓发出,记作A2。(3)细小或缺如型：第1跖背动脉管径细小或者缺如,记作A3。按照第1跖背动脉末端在趾璞处分支(Branch)吻合情况分为3型：(1)吻合型：第1跖背动脉与第1跖底动脉吻合且吻合支直径大于0.5mm,记作B1。(2)单发型：第1跖背动脉不与第1跖底动脉吻合,两者间的吻合支直径小于0.5mm,第1跖背动脉单独发出拇趾腓侧趾底动脉或单独发出第2趾胫侧趾底动脉,记作B2。(3)缺如型：第1跖背动脉在趾蹼处缺如或不参与拇趾和第2趾趾底血供,记作B3。按照第1跖背动脉在跖骨间隙走行(Course)情况分为3型。(1)间隙型：第1跖背动脉从第1骨间背侧肌近端双羽之间穿入到骨间背侧肌下方,走行于第1骨间背侧肌与第1跖骨间隙,逐渐紧贴第1跖骨向远端走行,远端浅出该肌至浅层,记作C1。(2)表浅型：第1跖背动脉走行于骨间背侧肌浅面,记作C2。(3)细小或缺如型,第1跖背动脉在第1跖骨间隙非常细小,血管直径小于0.5mm,对临床手术意义有限,记作C3。第1跖背动脉的类型依据上述三个关键点作为分类指标分别进行统计,然后综合表示所属类型,如：A1B1C1型、A2B1C1型等。结论保证组织瓣良好的血供灌注是手术成败的关键。在各种以第1跖背动脉为供血源动脉的组织瓣移植手术中,术者必须完整安全的解剖游离该动脉,因此对第1跖背动脉全面正确的评估对手术的安全性至关重要。由于现有文献对第1跖背动脉和第1骨间背侧肌的解剖的描述还不够准确,部分显微外科医生对此错误理解,可能会导致严重的后果。第1跖背动脉起源于足背动脉,足背动脉的起源也常存在变异,典型足背动脉为胫前动脉的直接延续,部分为腓动脉穿支的延续或以两根的形式起源于上述两动脉,无论胫前动脉延续或是腓动脉穿支延续发出的第1跖背动脉,本研究均将其归入A1型。在切取血管蒂时,术者常采取顺逆结合的分离方式,在近端如果在第1跖背动脉是A1型,这时血管由足背动脉分离出的位置常常较为表浅,在切断血管时比较容易,当血管来自足底动脉时,其发出点往往较深,此时往往需要将第1骨间背侧肌的胫侧头切开,牵拉向腓侧,从第1、2跖骨间隙内结扎切取。对于第1跖背动脉与第1跖底动脉的吻合情况,徐达传、孙博、王增涛等学者做了详细的解剖学研究,而本研究中将第1跖背动脉与第1跖底动脉吻合作为第1跖背动脉分型的一个关键指标,主要侧重临床手术的需要。对于B1型第1跖背动脉,由于第1跖背动脉与第1跖底动脉间存在着较粗的吻合支,可以第1跖背动脉为蒂分别切取拇甲瓣或第2足趾。当第1跖背动脉为B2型时,由于第1跖背动脉同第1跖底动脉之间没有吻合支或者吻合支细小(<0.5mm),第1跖背动脉仅发出第1趾蹼相对缘中一侧的趾底动脉,如拇趾腓侧或者第2趾胫侧趾底动脉,这种情况下临床上以第1跖背动脉为蒂只能切取一侧组织瓣。如B2型第1跖背动脉,单发出一只第2趾胫侧趾底动脉,则可以第1跖背动脉为蒂切取第2足趾、或者第2跖趾关节、第2趾胫侧皮瓣等,如果此时以第1跖背动脉为蒂切取拇甲瓣、拇趾腓侧皮瓣等则会导致手术失败。B2型第1跖背动脉虽然解剖比例不高,但是如果对其没有足够的认识而选择不当,将会导致严重后果。当为B3型时,第1跖背动脉和第1跖底动脉之间没有吻合或者吻合支非常纤细,临床中不能以第1跖背动脉为蒂切取拇甲瓣或者第2足趾移植。本研究所有资料中并未发现有Gilbert等学者,所表述的肌内型的存在,而占主要比例的是第1跖背动脉走行于第1骨间背侧肌与第1跖骨之间的间隙,并紧贴第1跖骨。受此前文献中描述的血管穿过肌肉内部影响,很多年轻医生在第1骨间背侧肌内寻找第1跖背动脉,需要切开骨间背侧肌部分或者全长,甚至为了保护第1跖背动脉将骨间背侧肌大部分携带在组织瓣血管蒂上,这样不仅破坏了第1骨间背侧肌,术后供区植皮成活率低,对患者损伤大愈后差；而且增加了手术难度,延长了手术时间。根据本研究发现,第1跖背动脉并不穿过第1骨间背侧肌肌肉内部,在第1骨间背侧肌胫腓侧两头之间,在两头的交汇处绕过第1骨间背侧肌胫侧头穿入至其跖侧,位于第1骨间背侧肌和第1跖骨体之间的间隙内紧贴第1跖骨体走行。且第1骨间背侧肌的胫侧头较小,仅相当于腓侧头的1/5.因此手术中解剖游离第1跖背动脉时,仅需要切断第1骨间背侧肌胫侧头,将其向腓侧牵拉翻起,即可清晰显露处于肌肉和跖骨体之间的第1跖背动脉。当血管游离切取后将切断的第1骨间背侧肌胫侧头断端缝合,尽可能恢复第1、2跖骨间隙原有的解剖结构,减少对组织的损伤。该入路显露清楚、切取简单,供区损伤小、恢复快。保证组织瓣良好的血供灌注是手术成败的关键。在各种以第1跖背动脉为供血源动脉的组织瓣移植手术中,术者必须完整安全的解剖游离该动脉,因此对第1跖背动脉全面正确的评估对手术的安全性至关重要。同时术者必须了解组织瓣供血动脉最终的血管来源、走行和分支分布。血管的来源为血液供应的源头,可以为组织瓣提供足够的血管蒂长度。供血动脉的终末分支,让术者了解组织瓣最终的血管供应方式,防止因无法明确组织瓣血供而导致的盲目切取,引起严重的并发症。本研究采用ABC分型法将起源、分布、走行三点作为分型的关键点,即该血管：“从哪里来,到哪里去,如何走行”三个方面总结第1跖背动脉的解剖特点,以临床解剖学资料为基础,以临床手术需要为目的,详尽的概括了第1跖背动脉的来源、分支、分布和走行类型。ABC分型法可以更好的显微外科医生理解第1跖背动脉的解剖类型,为临床中涉及该血管的相关手术,提高相关手术的安全性和简便性提供解剖学依据。更多还原

【Abstract】 "Like replaces like" is the basic principle in reconstructive microsurgery. Therefore, toe-to-hand transfer has been widely used for thumb and finger reconstruction with excellent results. However, the procedures are challenging mainly due to the great anatomical variations of the first dorsal metatarsal artery (FDMA). There are several classification systems of FDMA, with Gilbert’s classification is the most widely used one in clinical application. Fifty feet were injected with color latex and dissected in Gilbert’s original study in1976. Based on the anatomy of the first web space, FDMA was classified into three types depending on the relationship to the first dorsal interosseus muscle (FDIM). In most specimens in their study, FDMA was found to be superficial or lies in the FDIM. FDMA laid deep under FDIM in22%of their specimens. It also mentioned that FDMA were very slender in10%of the specimens. In1983, Leung classified FDMA into seven types based on their anatomical study of the first web space and the metatarsal area. The absence of the first plantar metatarsal artery (FPMA) and dorsalis pedis artery (DPA) were also included in their classification system. May and Lee reported different classification systems based on the sagittal course of FDMA. Lee (1997) classified FDMA into2groups based on both the origin of FDMA and the communication between FDMA and FPMA in the first metatarsal space. May concluded that the terminal branches of FDMA had three types of communication with FPMA, which included:(1) The terminal branch of FDMA joined the bifurcation of FPMA,(2) The terminal branch of FDMA joined the first plantar digital artery,(3) The terminal branch of FDMA joined the second plantar digital artery.From December,1998to December,2010, we performed more than600cases of toe-to-hand transfer for thumb and finger reconstruction and did48fresh cadaver dissections. The anatomy of FDMA was found to be different to that described in previous studies in the literature. We summarized our findings here and proposed a new classification system to help a surgeon to better understand the anatomy of FDMA and harvest FDMA based tissue transfer.MATERIALS AND METHODS:24fresh human cadavers were obtained from the Willed Body Program at Southern Medical University, Guangdong, China. Anatomical studies were done on the48foot specimens from these cadavers. The foot specimens were amputated at the ankle level, and the anterior or posterior tibial artery was cannulated and perfused with warmed saline until the venous return was clear. The specimens were then perfused with25ml red latex through anterior or posterior tibial artery and stored at-30℃until dissection. During the dissection, an incision was made on the dorsal aspect of foot from the ankle to the toes web space. Different parameters of FDMA were recorded, including its origin and diameter, relationship between FDMA and FDIM; diameter of its communicating branch with FPMA. The diameters of arteries were measured with a vernier caliper. The diameter of the FDMA’s communicating branch with FPMA was considered clinically significant if its diameter was0.5mm or larger.A total of30cast specimens were studied in our research.20ml of ethyl acetate was injected through the anterior or posterior tibial artery into each foot specimen to expand small blood vessels, and cast specimens were made by injecting a mixture of denture material and a perchloroethylene into the artery. Lixivium was used to corrode soft tissues while keeping bone intact in5of the cast specimens, whereas bones were removed in other cast specimens. The origin of FDMA and its communicating branch with FPMA were carefully examined.A total of148clinical cases were studied (116male,32female; aged5～58yrs, average33.5yrs). All patients had surgeries for free tissue transfer pedicled with FDMA, e.g.2nd toe transfer, and big toe wrap-around flap transfer, etc. Dissecting out FDMA (the pedicle) was the critical part of these procedures. The origin (arises), branches, and running course of FDMA were closely examined and recorded.CT angiography and three-dimensional reconstruction were done in5healthy adult volunteers. Informed consents were obtained from all5volunteers on CTA study. After the contrast media iohexol was injected into the cephalic veins, the feet were scanned with a multidetector CT (GE Discovery CT750HD). The data were processed by Volume rendering (VR), multiple planar reformation (MPR), curved planar reformation (CPR) and pseudo-color post-processing in a working-station (GE-ADW4.4).FDMA and DPA were examined by Ultrasound Color Doppler Imaging (CDI, GE Vivid7, M12L) in340feet of170healthy adult volunteers (98male,72female; aged15～60yrs, average37.5yrs). The origin and diameter of FDMA, and its relationship to the FDIM were recorded.ResultIn majority of our cases, FDMA originated from DPA, and ran toward the first web space. The average diameter of FDMA at the origin was (1.48±0.20)mm. Proximally, it passed under a muscular arch formed by the tibial head of FDIM. Distally, it proceeded superficially over the deep transverse metatarsal ligament. At the distal part of the1st web space, FDMA gave off two dorsal digital arteries, for blood supply of the great toe and the2nd toe. FDMA had many anatomic variations, including:its origin, running course in the first intermetatarsal space, anastomosis with FPMA, and diameters of FDMA and its branches.Anatomy of FDIMFDIM has two heads, the fibular head attached to the2nd metatarsal and the tibial head attached to the1st metatarsal. The muscle bellies from the two heads are fused together distally. It then passes dorsally over the deep transverse metatarsal ligament and inserts at the base of the proximal phalanx and dorsal digital aponeurosis of the2nd toe. The length of the attachment of the tibial head on the metatarsal is only about 1/5of that of the fibular head. Therefore, it is easy to cut the tibial head off the1st metatarsal instead of the fibular head.Anatomical relationship between FDMA and FDIMTwo different kinds of anatomical relationships between FDMA and FDIM in the first intermetatarsal space were observed in this study.1. FDMA runs superficial to FDIM. In this type, FDMA may branch directly from DPA or from the deep plantar branch of DPA when it perforates between the two head of FDIM. FDMA then courses distally towards the1st web space, lying superficial to FDIM. Around metatarsophalangeal joint level, FDMA sends out two dorsal digital arteries to supply the blood for the dorsal skin of the great and2nd toes. FDMA then proceeds over the deep transverse metatarsal ligament at the distal part of the first web space, and usually anastomoses with FPMA.2. FDMA runs in the space between FDIM and the first metatarsal. In84.29%of the specimens from our study, FDMA arose from DPA, coursed plantarly, and then passed under the muscular arch formed by the tibial head of FDIM. It ran closely to the first metatarsal. It coursed dorsally at the distal1/3of the space and superficially to the interosseus muscle. However, it always passed under the deep transverse metatarsal ligament. It gave off small muscular branches to FDIM.The anatomical patterns of FDMA can be easily observed in our cast specimens. The anatomical patterns of FDMA can be easily observed in our cast specimens. In86.67%of our cast specimens, FDMA arose from DPA (16.67%arose from DPA directly and70.00%from the deep plantar artery). In6.67%of the cast specimens, FDMA arose from the deep plantar arch directly or had a common trunk with FPMA that arose from the deep plantar arch. In83.33%of all the cast specimens, FDMA anastomosed with FPMA, and then gave off the fibular side plantar digital artery to the big toe and the tibial side plantar digital artery to the2nd toe. In13.33%of the cast specimens, FDMA and FPMA did not anastomose, or the diameter of the communicating branch between these two arteries was less than0.5mm. FDMA and FPMA individually sent out one main branch to supply one side of the first web space: fibular side of the great toe or tibial side of the2nd toe. This pattern was also found in the fresh cadaver dissections and clinical cases. In1case of all the cast specimens, FDMA did not anastomose with FPMA. FDMA gave off two branches of dorsal metatarsal arteries, while FPMA gave off two branches of plantar metatarsal arteries. There was no communication among these branches.CDI can quantitatively measure the real-time intravascular blood flow in the extremities noninvasively. In our study, CDI was used to monitor the blood flow to FDMA and DPA continuously. In84.12%of our340cases, FDMA lay in the space between FDIM and the first metatarsal. In11.76%of the cases, FDMA lay superficial to FDIM. We also recorded the origins of FDMA. FDMA arose from DPA in85.00%of the cases, and from the deep plantar arch along with FPMA about10.88%of the cases. FDMA was absent, or the diameter of FDMA was less than0.5mm in4.12%of our cases.It is convenient and accurate to illustrate the blood supply to the1st and2nd toes by using multidetector CT angiography. The continuous transformation images on the coronal plane show the positional relationship of the muscle and the artery. The artery and muscle were also located with the curved planar reformation technique, and3D reconstruction. In most of the cases in our study, FDMA coursed in the spaces between the first metatarsal and the FDIM. FDMA lies on the surface of the FDIM in a small percentage of our cases.In8.16%(16/196) of our fresh cadaver dissections and clinical cases, there was collateral FDMA. It arose from DPA along with FDMA, and runs superficial to FDIM. It usually anastomosed with the distal part of FDMA or FPMA and provided partial blood supply for the1st and2nd toes. The collateral FDMA had a small diameter (average0.5mm) in most cases. However, it had comparable diameter to FDMA in2cases in our study.In some cases, we could not find FDMA either in cadaver dissections or during surgeries. This could be due to the small caliber, or even absence of FDMA. This type is similar to Gilbert’s type III, and accounts for4.25%of all the cases. Intramuscular type of FDMA was described in the other classification systems in the literature, which refers to that FDMA went inside or through the FDIM. However, we didn’t find the intramuscular type of FDMA in all the surgical cases and anatomical specimens in this study, which contradict the previous classification systems.ABC classification method of FDMAWhen harvesting a FDMA based tissue for transfer, it is critical to know the origin, course and the main branches of the pedicle. Therefore, we proposed here a new clinical classification system to better describe the anatomy of FDMA based on these3key aspects of the artery:the origin of FDMA (Arise), the branches of FDMA in the first web space (Branch), and the course (Course) of FDMA in the first intermetatarsal space. We named this the "ABC" classification system of FDMA. First, the origin (Arise) of FDMA can be divided into3types:(1) the dorsal type (86.16%):FDMA originates from the DPA, as a direct continuation branch or derived from deep plantar artery, was denoted as A1;(2) the plantar type (9.46%):FDMA arises from the deep plantar arch or arising from the same branch of the deep plantar arch together with FPMA. It was denoted as A2;(3) slender type (4.38%):diameter of FDMA was smaller than0.5mm,or it was too slender to be found in operations and in perfused specimens. It was denoted as A3.Second, the main terminal branches (Branch) of FDMA in the first web space can be divided into3types:(1) B1, communication type (84.96%):FDMA and FPMA anastomoses with each other, and the diameter of the communicating branches larger than0.5mm.This type is safe for tissue transfer pedicled with FDMA.(2) B2, independent type (9.73%):FDMA and FPMA don’t anastomoses with each other, or the diameter of the communicating branch between these two arteries is less than0.5mm. FDMA and FPMA independently send out one main branch to supply one side of the first web space, fibular side of the great toe and tibial side of the2nd toe. Therefore, only one side of tissue, either great toe or the2nd toe, can be harvested based on FDMA.(3) B3, the slender type (5.31%):the diameter of the terminal branch of FDMA is smaller than0.5mm, or there is no significant anastomosis with FPMA. The great and2nd toes were mainly supplied by FPMA. Therefore, free tissue transfer can’t be harvested based on FDMA.Third, the course (Course) of FDMA in the first intermetatarsal space can be divided into3types according to the spatial relationship between FDMA and FDIM.(1)C1, interspace type (84.29%):FDMA goes under the tibial head of FDIM and courses into the interspace formed by FDIM and the first metatarsal. It stays closer to the first metatarsal at the distal part of the interspace and courses superficially towards the dorsum of the foot and passes over the deep transverse metatarsal ligament.(2) C2, superficial type (11.46%):FDMA runs superficial to FDIM during the whole course.(3)C3, slender type (4.25%):The diameter of FDMA is less than0.5mm and it is difficult to be found and dissected out. It is not suitable to do FDMA based free tissue transfer.Our ABC classification system is based on the three fundamental characteristics of FDMA:origin (arising), branches and its course. FDMA can be classified by combining these three basic characteristics, e.g. Type:A1B1C1and A2B1C1etc.DiscussionFDMA based free tissue transfer has been widely used in reconstructive microsurgery. Familiar with the anatomy of FDMA is the key to ensure the sufficient blood perfusion for the transferred tissue. The ABC classification system that we described here gives a more accurate and clear description of the anatomy of FDMA for surgery purpose.FDMA originates from DPA or one of its branches. However, the origin of the DPA also has many variations. DPA can be as a direct continuation of the anterior tibial artery, which is the most common type. It can also be a direct continuation of the peroneal artery, or from the communicating branch of the anterior tibial artery and peroneal artery. Regardless of its different origins, DPA is defined by its location on the dorsum of the foot and supply blood to tissues around the first web space. FDMA originating from DPA or the deep plantar artery is classified as type Ajin this study.Retrograde dissection of the pedicle was suggested in the toe-to-hand transfer surgery.The origin of the type A1of FDMA is superficial and the dissection of the pedicle is easy. If the origin of FDMA is type A2, the tibial head of the first interosseus should be divided and retracted to fibular side in order to dissect out the pedicle.Many detailed anatomical studies have been done to investigate the different anastomosing types between FDMA and FPMA. This is the basis for the type B (branches) in our classification system, which is also one of the critical parts in harvesting FDMA based tissue transfer. In type B1of FDMA, the anastomosing branch is big enough (the diameter>0.5mm) for the blood from FDMA to flow through to the plantar digital artery. Therefore, it is safe to harvest FDMA based2nd toe and/or great toe tissue transfer. There are2patterns of type B2for the anatomy of FDMA:it is either running towards the fibular side of the great toe or the tibial side of the2nd toe. Therefore, only one side of the tissue, either the great toe or the2nd toe, can be harvested for tissue transfer pedicled with FDMA. If the wrong side of tissue is harvested, the surgery will fail. In type B3, the anastomosing branch of FDMA to the plantar digital arteries will be too slender for harvesting any FDMA pedicled great toe or2nd toe tissue transfer.The intramuscular type described by Gilbert that FDMA coursed inside the interosseus muscle was not found in any cases of our study. The most common type was type C1of FDMA. Many literatures described that FDMA coursed inside or under FDIM and lots of surgeons have the misconception that this is the most common anatomy type of FDMA. Therefore, they may cut open FDIM and try to dissect out to FDMA. This will cause many pitfalls of the surgery:damaging FDIM, jeopardizing the blood supply to the skin, and making the procedure more complicated and prolonging the surgical time etc. According to our study, FDMA does not course inside FDIM. In type C1of FDMA, the tibial head is easy to be divided and retracted to the fibular side. FDMA can then be easily dissected out in the space between FDIM and the first metatarsal.The tibial head of the muscle can be sutured back as much as possible after the pedicle has been dissected out.CDI is noninvasive, convenient, safe and cheap. The results of CDI are consistent with intraoperative findings. It can be used preoperatively to quantitatively measure the intravascular blood flow and classify FDMA. Therefore, a surgeon can know the anatomical variations of FDMA before a surgery by using CDI study.We described detailed anatomical variations of FDMA in this study, especially the findings that were critical for harvesting a FDMA base vascularized free tissue transfer. We also propose an "ABC" classification system based on this study. It can give a surgeon a clear picture of different anatomical variations of FDMA and help him/her to easily and successfully harvest a vascularized tissue transfer based on FDMA.更多还原