Gordon Michael, Peppelman Walter C, Beutler William, OʼHalloran Damien, Chinthakunta Suresh R, Bucklen Brandon
*Newport Orthopedic Institute, Newport Beach, CA †Pennsylvania Spine Institute, Harrisburg ‡Globus Medical Inc., Audubon, PA.
Clin Spine Surg. 2017 Feb;30(1):E31-E37. doi: 10.1097/BSD.0b013e31829a37ce.
An in vitro biomechanical study.
To determine the fracture reduction achieved by a novel inflatable bone tamp under simulated physiological load.
Previous biomechanical studies have showed that kyphoplasty allows near-total restoration of lost vertebral height in unloaded conditions and partial height restoration under simulated physiological loads. Clinically, loss of reduction has been observed after bone tamp deflation, before cement injection. The present study evaluated fracture reduction achieved by an inflatable bone tamp during kyphoplasty while maintaining physiological load. Comparison to commercially available inflatable bone tamp was also performed.
Eighteen osteoporotic vertebral bodies (T11-L4) were alternately assigned to one of the 2 treatment groups: group A-AFFIRM (Algea Thearpies, a division of Globus Medical Inc., Audubon, PA); and group B-KYPHON (Kyphon Inc., Sunnyvale, CA). The vertebral bodies were compressed axially on an MTS Bionix 858 machine at a rate of 5 mm/min until compressed to 40% of the initial anterior height. Load versus displacement was recorded. The fractured VBs then underwent kyphoplasty with cement augmentation. The augmented vertebral bodies were then recompressed and anterior vertebral body height (mm) and wedge angle (degrees) was measured initially, after mechanically creating an anterior wedge fracture, and after repairing the compression fracture. Each vertebral body was subjected to 111 N load to simulate in vivo physiological loading during inflation and cement augmentation. The vertebral height, wedge angle, cement volume, and inflation pressures were compared between the treatment groups using an unpaired t test (P<0.05). Failure loads were compared between intact and repaired VBs using a paired t test (P<0.05).
Average lost height restored in group A was 29%, and 30% in group B compared to the compressed state. Similar trends were observed in the mean changes of vertebral body wedge angle in both the groups. No significant difference in mean inflation pressures (group A 182±33 psi; group B 175±37 psi) were found between the 2 groups. Average percentage increase in failure load was 218% and 241% for groups A and B, respectively. Mean injected cement volume was 6.65±0.65 and 6.73±0.41 mL for groups A and B, respectively.
Some height restoration was observed using the 2 bone tamps in fractured vertebral bodies under simulated physiological load. The fracture reduction achieved by the 2 inflatable bone tamps was equivalent. No significant difference between mean inflation pressures and failure load was demonstrated between the 2 groups.
一项体外生物力学研究。
确定一种新型充气式骨填充器在模拟生理负荷下实现的骨折复位情况。
以往的生物力学研究表明，椎体后凸成形术在无负荷条件下可使丢失的椎体高度近乎完全恢复，在模拟生理负荷下可部分恢复椎体高度。临床上，在注入骨水泥之前，已观察到骨填充器放气后复位丢失的情况。本研究评估了椎体后凸成形术期间充气式骨填充器在维持生理负荷时实现的骨折复位情况。还与市售充气式骨填充器进行了比较。
将18个骨质疏松性椎体（T11 - L4）交替分配到2个治疗组之一：A组 - AFFIRM（Globus Medical Inc.旗下的Algea Thearpies公司，宾夕法尼亚州奥杜邦）；B组 - KYPHON（Kyphon公司，加利福尼亚州森尼韦尔）。在MTS Bionix 858机器上以5毫米/分钟的速度对椎体进行轴向压缩，直至压缩至初始前高度的40%。记录负荷与位移情况。然后对骨折的椎体进行椎体后凸成形术并注入骨水泥强化。随后对强化后的椎体再次进行压缩，并在机械制造前楔形骨折后、修复压缩骨折后，分别测量椎体前高度（毫米）和楔形角（度）。在充气和注入骨水泥期间，对每个椎体施加111 N的负荷以模拟体内生理负荷。使用不成对t检验比较治疗组之间的椎体高度、楔形角、骨水泥体积和充气压力（P<0.05）。使用配对t检验比较完整椎体和修复椎体之间的破坏负荷（P <0.05）。
与压缩状态相比，A组平均恢复的丢失高度为29%，B组为30%。两组椎体楔形角的平均变化也观察到类似趋势。两组之间平均充气压力无显著差异（A组182±33 psi；B组175±37 psi）。A组和B组破坏负荷的平均增加百分比分别为218%和241%。A组和B组平均注入的骨水泥体积分别为6.65±0.65毫升和6.73±0.41毫升。
在模拟生理负荷下，使用这两种骨填充器在骨折椎体中观察到了一定程度的高度恢复。两种充气式骨填充器实现的骨折复位效果相当。两组之间平均充气压力和破坏负荷无显著差异。
