Sferra J, Kambic H E, Schickendantz M S, Watson J T
Department of Orthopaedics, Cleveland Clinic Foundation, OH 44195, USA.
Clin Orthop Relat Res. 1995 Feb(311):222-6.
The mechanical integrity of tibial bone treated by distraction osteogenesis (callotasis) using an Orthofix external fixator was evaluated in a group of 6 dogs. Diaphyseal corticotomies were performed on Day 0. Distraction was begun on Day 8, at a rate of 0.33 mm every 8 hours. On Day 34, the Orthofix frame was locked. On Day 56, the frames were removed and the dogs were euthanized. Radiographs were taken weekly to assess regenerate bone formation and extent of tibial bone lengthening, which averaged 12 mm (range, 5-20 mm). One dog showed incomplete bony union that was attributed to pin loosening. Torsional testing of lengthened and contralateral control tibiae resulted in spiral diaphyseal fractures. Five of 6 lengthened tibiae bones fractured within the diaphysis, but outside the regenerate area, suggesting that the strength of the lengthened segment exceeded that of the original diaphysis which was exposed to stress shielding by the external fixator. These observations have led to a method to test and evaluate lengthened bone at the time of frame removal and to monitor the effectiveness of this type of technique.
在一组6只犬中，对使用Orthofix外固定器通过牵张成骨术（骨痂延长术）治疗的胫骨的机械完整性进行了评估。在第0天进行骨干皮质切开术。在第8天开始牵张，以每8小时0.33毫米的速度进行。在第34天，锁定Orthofix框架。在第56天，拆除框架并对犬实施安乐死。每周拍摄X线片以评估再生骨形成情况和胫骨延长程度，平均延长12毫米（范围为5 - 20毫米）。一只犬显示骨愈合不完全，归因于克氏针松动。对延长的胫骨和对侧对照胫骨进行扭转测试，结果导致骨干螺旋骨折。6只延长的胫骨中有5只在骨干内但在再生区域外发生骨折，这表明延长段的强度超过了因外固定器应力遮挡而承受应力的原始骨干的强度。这些观察结果促成了一种在拆除框架时测试和评估延长骨并监测此类技术有效性的方法。
