Matsukawa Keitaro, Yato Yoshiyuki, Hynes Richard A, Imabayashi Hideaki, Hosogane Naobumi, Asazuma Takashi, Matsui Toshiyasu, Kobayashi Yasushi, Nemoto Koichi
*Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama †Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Tokyo, Japan ‡Department of Engineering, Florida Institute of Technology, Melbourne, FL §Department of Anatomy and Neurobiology, National Defense Medical College, Tokorozawa, Saitama, Japan.
Clin Spine Surg. 2017 Jun;30(5):E497-E504. doi: 10.1097/BSD.0000000000000130.
A morphometric measurement of new thoracic pedicle screw trajectory using computed tomography and a biomechanical study on cadaveric thoracic vertebrae using insertional torque.
To introduce a new thoracic pedicle screw trajectory which maximizes engagement with denser bone.
Cortical bone trajectory (CBT) which maximizes the thread contact with cortical bone provides enhanced screw purchase. Despite the increased use of CBT screws in the lumbar spine, no study has yet reported the insertional technique for thoracic CBT.
First, the computed tomography scans of 50 adults were studied for morphometric measurement of lower thoracic CBT. The starting point was determined to be the intersection of the lateral two thirds of the superior articular process and the inferior border of the transverse process. The trajectory was straight forward in the axial plane angulated cranially targeting the posterior third of the superior endplate. The maximum diameter, length, and the cephalad angle were investigated. Next, the insertional torque of pedicle screws using this new technique was measured and compared with that of the traditional technique on 24 cadaveric thoracic vertebrae.
All morphometric parameters of thoracic CBT increased from T9 to T12 (the mean diameter: from 5.8 mm at T9 to 8.5 mm at T12; the length: from 29.7 mm at T9 to 32.0 mm at T12; and the cephalad angle: from 21.4 degrees at T9 to 27.6 degrees at T12). The mean maximum insertional torque of CBT screws and traditional screws were 1.02±0.25 and 0.66±0.15 Nm, respectively. The new technique demonstrated average 53.8% higher torque than the traditional technique (P<0.01).
The detailed morphometric measurement and favorable screw fixation stability of thoracic CBT are reported. The insertional torque using thoracic CBT technique was 53.8% higher than that of the traditional technique.
使用计算机断层扫描对新型胸椎椎弓根螺钉轨迹进行形态测量，并对尸体胸椎进行插入扭矩的生物力学研究。
引入一种新型胸椎椎弓根螺钉轨迹，使与更致密骨的接触最大化。
皮质骨轨迹（CBT）可使螺纹与皮质骨的接触最大化，从而增强螺钉的把持力。尽管CBT螺钉在腰椎中的使用越来越多，但尚无研究报道胸椎CBT的插入技术。
首先，对50名成年人的计算机断层扫描进行研究，以测量下胸椎CBT的形态。起点确定为上关节突外侧三分之二与横突下缘的交点。轨迹在轴向平面上向前，向头侧成角，目标是上位终板的后三分之一。研究了最大直径、长度和头侧角度。接下来，在24个尸体胸椎上测量使用这种新技术的椎弓根螺钉的插入扭矩，并与传统技术的插入扭矩进行比较。
胸椎CBT的所有形态学参数从T9到T12均增加（平均直径：从T9的5.8mm增加到T12的8.5mm；长度：从T9的29.7mm增加到T12的32.0mm；头侧角度：从T9的21.4度增加到T12的27.6度）。CBT螺钉和传统螺钉的平均最大插入扭矩分别为1.02±0.25和0.66±0.15 Nm。新技术的扭矩平均比传统技术高53.8%（P<0.01）。
报告了胸椎CBT的详细形态测量和良好的螺钉固定稳定性。使用胸椎CBT技术的插入扭矩比传统技术高53.8%。
