Breeze S W, Doherty B J, Noble P S, LeBlanc A, Heggeness M H
Department of Orthopedic Surgery, Institute for Spinal Disorders, Baylor College of Medicine, Houston, Texas, USA.
Spine (Phila Pa 1976). 1998 Sep 1;23(17):1829-31. doi: 10.1097/00007632-199809010-00004.
The pullout strength of unicortical and bicortical screws in thoracic and lumbar vertebral bodies was measured as a function of bone mineral density.
To determine the influence of bone mineral density and screw insertion technique on the stability of anterior thoracolumbar spine screw fixation.
No previous study has addressed the specific technique of screw insertion or stability of screw fixation in the anterior spine.
Fifty-one human thoracic vertebral bodies were tested in pullout with 6.55-mm cancellous screws inserted using unicortical and bicortical techniques.
Pullout force increased exponentially with increasing bone mineral density for unicortical and bicortical screws. Bicortical screws were significantly stronger in resisting pullout than unicortical screws.
Advancing an anterior vertebral body screw to engage the second cortex increases resistance to pullout by 25-44%, depending on vertebral bone mineral density. The difference in resistance between unicortical and bicortical techniques was smaller in specimens with low mineral densities.
测量胸腰椎椎体中单皮质和双皮质螺钉的拔出强度，并将其作为骨密度的函数。
确定骨密度和螺钉置入技术对胸腰椎前路脊柱螺钉固定稳定性的影响。
此前尚无研究探讨前路脊柱螺钉置入的具体技术或螺钉固定的稳定性。
使用单皮质和双皮质技术，用6.55毫米的松质骨螺钉对51个人类胸椎椎体进行拔出试验。
单皮质和双皮质螺钉的拔出力均随骨密度增加呈指数增长。双皮质螺钉抵抗拔出的能力明显强于单皮质螺钉。
推进椎体前路螺钉使其与第二层皮质骨啮合，可使拔出阻力增加25%至44%，具体取决于椎体骨密度。在骨密度较低的标本中，单皮质和双皮质技术之间的阻力差异较小。
