Slate R K, Posnick J C, Wells M D, Goldstein J A, Keeley F W, Thorner P S
Division of Plastic Surgery, Hospital for Sick Children, Toronto, Ontario, Canada.
Plast Reconstr Surg. 1993 Oct;92(5):874-83.
Although clinical and experimental findings have demonstrated that fetal soft-tissue wounds heal without scarring, very little is known about the process of fetal bone healing. This study examined fetal long bone healing in utero, both histologically and biochemically, with and without fracture fixation in a fetal sheep model. Our study group consisted of 25 live fetuses (from 16 ewes). There were 50 fetal tibias in this group; 12 were control, 17 were fixed (miniplate fixation), and 21 were nonfixed. A midshaft osteotomy of the tibia, either fixed or non-fixed, was performed on fetal sheep at 95 days' gestation (term = 145 days) in utero. The sheep were then killed at one of five postoperative time intervals (weeks 1, 2, 3, 4, and 7), and fetal bone healing was examined. The variables reviewed included gross morphology, histology, radiology, and collagen analysis (proportions of types II to I and III to I collagen). Fetal bone healing without fixation was accompanied by a large callus with rapid and abundant cartilage and collagen deposition. Bone healing was characterized by malunion or nonunion at 7 weeks. However, with miniplate and screw fixation, callus formation was minimal; primary bone healing occurred by 3 weeks and did not adversely affect long bone growth. Analysis of callus samples revealed a minimal amount of type III collagen, whereas the proportion of type II collagen was variable and proportional to the content of callus cartilage.
尽管临床和实验结果表明胎儿软组织伤口愈合后不留疤痕，但对于胎儿骨骼愈合过程却知之甚少。本研究在胎儿绵羊模型中，通过组织学和生物化学方法，对有或没有骨折固定情况下的子宫内胎儿长骨愈合进行了研究。我们的研究组由25只活胎儿（来自16只母羊）组成。该组共有50根胎儿胫骨；12根为对照组，17根进行了固定（微型钢板固定），21根未固定。在妊娠95天（足月为145天）的子宫内对胎儿绵羊的胫骨进行中段截骨术，截骨后胫骨要么固定要么不固定。然后在术后五个时间间隔（第1、2、3、4和7周）中的某一个时间点将绵羊处死，并检查胎儿骨骼愈合情况。评估的变量包括大体形态、组织学、放射学和胶原蛋白分析（II型与I型以及III型与I型胶原蛋白的比例）。未固定的胎儿骨骼愈合伴有大量骨痂形成，软骨和胶原蛋白快速大量沉积。在7周时，骨骼愈合的特征为畸形愈合或不愈合。然而，采用微型钢板和螺钉固定时，骨痂形成极少；3周时发生一期骨愈合，且对长骨生长没有不利影响。对骨痂样本的分析显示III型胶原蛋白含量极少，而II型胶原蛋白的比例则各不相同，且与骨痂软骨的含量成比例。
