单节段椎弓根螺钉固定联合上方棘突间Coflex置入的生物力学评价

Biomechanical evaluation for single-level rigid fixation combined with Coflex implantation

中文关键词:  腰椎坚强固定  棘突间装置  生物力学

英文关键词:Rigid fixation  Interspinous divece  Biomechanical test

中文摘要:

  【摘要】 目的：对腰椎单节段椎弓根螺钉固定联合上节段使用棘突间Coflex置入手术（Topping-off手术）进行生物力学评价。方法：采用6具男性L3～S1节段的人脊柱标本，建立L4/5椎弓根螺钉坚强固定（后路腰椎体间融合术，PLIF）模型及L4/5椎弓根螺钉固定联合L3/4棘突间Coflex置入（Topping-off手术）的模型。每具标本均进行完整、坚强固定和联合固定3种状态的生物力学测试。分别比较完整标本（A组）、L4/5坚强固定（B组）、联合固定（C组）中L3/4和L5/S1节段活动度及椎间盘内压差异。结果：B组L3/4节段平均活动度较A组显著增加（P<0.05）（分别比A组前屈增大0.54°，后伸增大0.34°，侧弯增大0.30°，旋转增大0.19°）；B组L5/S1活动度亦比A组增加，但无统计学意义（P>0.05）。C组L3/4节段的活动度与B组相比，后伸方向显著减小（P<0.05）（比B组减小0.32°），而前屈、侧弯、旋转减小不明显（P>0.05）；与A组相比，后伸及旋转无显著增大（P>0.05），前屈及侧屈有显著增大（P<0.05）（分别比A组前屈增大0.38°，侧屈增大0.28°）。C组L5/S1活动度与B组相比，除前屈方向外均有增大趋势，但无统计学意义（P>0.05）；与A组比较，均有增大，但无统计学意义（P>0.05）。与A组相比，B组L3/4椎间盘内压显著增加（P<0.05）（分别比A组前屈增大0.78kPa，后伸增大0.88kPa，侧弯增大1.84kPa，旋转增大1.45kPa）；L5/S1椎间盘内压也显著增加（P<0.05）（分别比A组前屈增大1.21kPa，后伸增大0.94kPa，侧弯增大0.70kPa，旋转增大0.81kPa）。与B组相比，C组L3/4椎间盘内压减小（分别比B组前屈减小0.29kPa，后伸减小1.39kPa，侧弯减小0.13kPa，旋转减小0.10kPa），但仅后伸减小有统计学意义（P<0.05）；C组L5/S1椎间盘内压分别比B组前屈减小0.39kPa，后伸减小0.10kPa，侧弯增大0.15kPa，旋转增加0.18kPa，但无统计学意义（P>0.05）。与A组相比，C组L3/4椎间盘内压增大，其中前屈、侧屈及旋转显著增大（P<0.05）（分别比A组前屈增大1.53kPa，侧屈增大1.71kPa，旋转增大1.35kPa）；C组L5/S1椎间盘内压也显著增大（P<0.05）（分别比A组前屈增大0.82kPa，后伸增大0.84kPa，侧屈增大0.85kPa，旋转增大0.99kPa）。结论：生物力学测试发现，Topping-off手术中Coflex对单节段坚强固定上方相邻节段有保护作用；但使下方相邻节段的应力增加，可能对远期退变产生不良影响。

英文摘要:

  【Abstract】 Objectives: To evaluate the biomechanical effect of topping-off operation with Coflex interspinous dynamic device combined with adjacent monosegmental rigid fixation by pedical screw in lumbar spine. Methods: 6 fresh frozen human cadaveric lumbar spine specimens(6 males) were tested. Models of L4/5 rigid fixation by pedical screw(posterior lumbar interbody fusion, PLIF) and models of L4/5 rigid fixation by pedical screw combined with L3/4 Coflex were established. On each specimen, range of segmental motion(ROM) and intradiscal pressure(IDP) of L3/4 and L5/S1 were tested in the condition of intact(group A), rigid fixation(L4/5)(group B) and combined with Coflex(L3/4)(group C), respectively. Results: The L3/4 ROM of group B was higher than that of group A significantly(P<0.05). The L3/4 ROM of group B in flexion, extension, lateral bending and axial rotation increased by 0.54°, 0.34°, 0.30° and 0.19°, respectively. The L5/S1 ROM of group B increased with no statistical significance(P>0.05), compared with group A. The L3/4 ROM of group C was lower than that of group B(P<0.05) only in the extension, while the decreases were not significant in other directions. Compared with group A, the L3/4 ROM of group C did not increase significantly in the extension and axial rotation(P>0.05), while it increased significantly in flexion(0.38°) and lateral bending(0.28°), respectively. Compared with group B, the L5/S1 ROM of group C had a increasing trend in extension, lateral bending and axial rotation, but no statistical significance(P>0.05). Compared with group A, the L5/S1 ROM of group C had a increasing trend in all directions(P>0.05). The L3/4 IDP of group B was higher than that of group A(P<0.05). The L3/4 IDP of group B in flexion, extension, lateral bending and axial rotation increased by 1.82kPa, 1.88kPa, 1.84kPa and 1.45kPa, respectively. The L5/S1 IDP of group B in flexion, extension, lateral bending and axial rotation increased by 1.21kPa, 0.94kPa, 0.70kPa and 0.81kPa, respectively(P<0.05). The L3/4 IDP of group C was lower than that of group B only in the extension(P<0.05). Compared with group A, the L3/4 IDP of group C in flexion, lateral bending and axial rotation increased by 1.53kPa, 1.71kPa and 1.35kPa, respectively(P<0.05). Compared with group B, L5/S1 IDP of group C increased in lateral bending and axial rotation, but no statistical significance(P>0.05). Compared with group A, L5/S1 IDP of group C in flexion, extension, lateral bending and axial rotation increased by 0.82kPa, 0.84kPa, 0.85kPa and 0.99kPa, respectively(P<0.05). Conclusions: Biomechanical evidence supports the protective effect of interspinous device on upper adjacent segments after monosegmental rigid fixation. It may increase the stress of lower adjacent segment which may induce adverse effects in the long-term period.