Movassaghi K, Altobelli D E, Zhou H
Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, USA.
J Oral Maxillofac Surg. 1995 Sep;53(9):1033-42; discussion 1042-3. doi: 10.1016/0278-2391(95)90121-3.
This study investigated the ability to use titanium screws to provide stable skeletal points in the growing craniofacial region of the rabbit for suture expansion. These screws provided sites for direct application of external forces to alter growth and anatomic form.
Twenty-one rabbits (30 days old) were divided into three groups: control (n = 9), experimental (n = 9, and sham (n = 3). Four four-holed AO/ASIF commercially pure titanium craniofacial plates were contoured into an L-shape with a 90 degree angle at the midpoint. The plates were placed bilaterally in the frontal and nasal bone sites and secured with 2.0-mm diameter, 4-mm long, commercially pure titanium screws in both the sham and experimental groups. After 4 week of healing, a spring mechanism with a distraction force of 55 g was activated between ipsilateral plates and across the frontonasal sutures bilaterally in the experimental group for 5 weeks. No force was applied between the plates in the sham group. A preliminary evaluation of the bone-implant interface and the changes in the suture was done histologically. Morphologic changes were measured using cephalometric radiographs and direct anatomic measurements.
The experimental group showed a significant increase in growth across the frontonasal suture in comparison with the sham group (P < .05). In addition, an increase in the length of the nasal and frontal bones in the expanded group was observed in comparison with the control and sham groups (P < .05). Histologically, a mixture of woven and lamellar bone was seen in the suture region and lamellar bone was seen in the screw-bone interface.
This study indicates that titanium screws in the developing rabbit skull can provide stable sites for the direct application of external forces, producing secondary changes in skeletal morphology. This laboratory models provides a useful system for the further study of growth modification using such external mechanical forces.
本研究探讨了使用钛螺钉在生长中的兔颅面部区域提供稳定的骨骼点以进行缝合扩张的能力。这些螺钉为直接施加外力以改变生长和解剖形态提供了部位。
将21只30日龄的兔子分为三组：对照组（n = 9）、实验组（n = 9）和假手术组（n = 3）。将四块四孔AO/ASIF商业纯钛颅面骨板加工成L形，中点处呈90度角。在假手术组和实验组中，将骨板双侧放置在额骨和鼻骨部位，并用直径2.0毫米、长4毫米的商业纯钛螺钉固定。愈合4周后，在实验组中，激活一个牵张力为55克的弹簧装置，在同侧骨板之间并双侧跨过额鼻缝，持续5周。假手术组的骨板之间不施加力。通过组织学方法对骨-植入物界面和缝合处的变化进行初步评估。使用头颅侧位X线片和直接解剖测量来测量形态学变化。
与假手术组相比，实验组额鼻缝处的生长显著增加（P < .05）。此外，与对照组和假手术组相比，扩张组的鼻骨和额骨长度增加（P < .05）。组织学上，在缝合区域可见编织骨和板层骨的混合，在螺钉-骨界面可见板层骨。
本研究表明，发育中的兔颅骨中的钛螺钉可为直接施加外力提供稳定部位，从而引起骨骼形态的继发性变化。该实验室模型为进一步研究使用这种外部机械力进行生长改变提供了一个有用的系统。
