Truumees Eeric, Demetropoulos Constantine K, Yang King H, Herkowitz Harry N
William Beaumont Hospital, Royal Oak, Michigan, USA.
Spine (Phila Pa 1976). 2002 Nov 15;27(22):2441-5. doi: 10.1097/00007632-200211150-00005.
An in vitro biomechanical study using a calibrated distractor and a subminiature load cell in a cadaver anterior cervical discectomy construct was conducted.
To study the interrelations of preoperative disc height, graft height, and compressive and distractive forces in an anterior cervical discectomy model.
The effects of graft size on compressive and distractive forces in a discectomy model remain unknown. Larger grafts afford neural decompression through anterior column distraction. This distraction may subject the graft and vertebral bodies to excessive loads, increasing graft fracture, and subsidence risk.
Disc height was measured radiographically in 18 specimens. A Smith-Robinson discectomy was performed, and the superior and inferior ends of the specimens were embedded in polyester resin. Distraction was applied through a calibrated Caspar distractor to measure the distractive force applied while steel spacers rigidly fixed to a subminiature load cell were introduced. After distraction was removed, immediate compressive force was measured.
Distractive forces of 112.4 N and 189.9 N were required to insert the 6-mm and 8-mm grafts, respectively. When this distractive force was removed, immediate compressive loads of 8.8 N and 21.5 N on the graft were noted. When a compressive load of 45 N was applied in a loading frame, measured graft loads of 16.2 N and 29.2 N also increased. No statistically significant relation was observed between preoperative disc height and distractive force or compression of the graft. Significantly lower distractive and compressive forces were associated with insertion of the 6-mm rather than 8-mm graft.
Significantly higher distractive and compressive forces were recorded with larger grafts. Preoperative disc height was not an accurate predictor of graft loads.
采用校准牵开器和超小型测力传感器，在尸体颈椎前路椎间盘切除模型上进行体外生物力学研究。
研究颈椎前路椎间盘切除模型中术前椎间盘高度、移植骨高度以及压缩力和牵张力之间的相互关系。
在椎间盘切除模型中，移植骨大小对压缩力和牵张力的影响尚不清楚。较大的移植骨通过前柱撑开实现神经减压。这种撑开可能使移植骨和椎体承受过大负荷，增加移植骨骨折和下沉风险。
对18个标本进行影像学测量椎间盘高度。施行Smith-Robinson椎间盘切除术，将标本的上下端嵌入聚酯树脂。通过校准的Caspar牵开器施加牵张力，在引入刚性固定于超小型测力传感器的钢制垫片时测量所施加的牵张力。去除牵张力后，立即测量压缩力。
分别插入6毫米和8毫米移植骨时所需的牵张力为112.4牛和189.9牛。去除该牵张力后，观察到移植骨上立即产生的压缩负荷分别为8.8牛和21.5牛。在加载框架中施加45牛的压缩负荷时，测得的移植骨负荷也分别增加至16.2牛和29.2牛。术前椎间盘高度与移植骨的牵张力或压缩力之间未观察到统计学上的显著关系。与插入8毫米移植骨相比，插入6毫米移植骨时的牵张力和压缩力明显更低。
较大的移植骨记录到明显更高的牵张力和压缩力。术前椎间盘高度并非移植骨负荷的准确预测指标。
