Samchukov M L, Cope J B, Harper R P, Ross J D
Texas Scottish Rite Hospital for Children, Dallas 75219, USA.
J Oral Maxillofac Surg. 1998 Jan;56(1):51-9. doi: 10.1016/s0278-2391(98)90916-8.
Experience using distraction osteogenesis for limb lengthening has shown the importance of appliance orientation. Although successful results of mandibular lengthening using osteodistraction have been reported, optimal orientation of the distractors relative to the mandible has not been determined. The purpose of this study was to evaluate the biomechanical effects of linear distractors placed parallel to the body of the mandible or parallel to the axis of distraction.
A two-dimensional model of the human mandible was generated for computer simulation of mandibular osteodistraction. Linear distractors were then analyzed based on their orientation, either parallel to the body of the mandible or parallel to the axis of distraction. In addition, two types of distraction osteogenesis procedures for mandibular reconstruction were analyzed: 1) bilateral mandibular lengthening, and 2) bilateral mandibular lengthening in combination with midline mandibular widening.
Distractors oriented parallel to the body of the mandible caused a lateral displacement of the posterior components of the distraction devices and a reduction of the midline distraction gap during mandibular lengthening. These effects were eliminated when the device was oriented parallel to the axis of distraction. Midline symphyseal widening created axial rotation of the mandibular condyles regardless of the orientation of the distractors.
Distraction appliances must be oriented parallel to the axis of distraction to prevent adverse biomechanical effects during bilateral mandibular lengthening. Additional ramus osteotomies, using hinged devices for angular correction, may be necessary to compensate for rotational movements of the mandibular condyles secondary to midline osteodistraction.
利用牵张成骨技术进行肢体延长的经验表明了器械定向的重要性。尽管已有报道称使用骨牵张技术进行下颌骨延长取得了成功，但牵张器相对于下颌骨的最佳定向尚未确定。本研究的目的是评估与下颌骨体平行放置或与牵张轴平行放置的线性牵张器的生物力学效应。
生成人类下颌骨的二维模型，用于下颌骨牵张成骨的计算机模拟。然后根据线性牵张器的定向进行分析，其定向为与下颌骨体平行或与牵张轴平行。此外，还分析了两种用于下颌骨重建的牵张成骨手术：1）双侧下颌骨延长，以及2）双侧下颌骨延长联合下颌骨中线增宽。
与下颌骨体平行定向的牵张器在下颌骨延长过程中导致牵张装置后部组件向外侧移位，并使中线牵张间隙减小。当牵张器与牵张轴平行定向时，这些影响被消除。无论牵张器的定向如何，中线联合处增宽都会导致下颌髁突发生轴向旋转。
牵张器械必须与牵张轴平行定向，以防止双侧下颌骨延长过程中出现不良生物力学效应。可能需要额外的升支截骨术，并使用铰链装置进行角度矫正，以补偿中线牵张成骨继发的下颌髁突旋转运动。
