MRI辅助髓核容积测定评价单侧椎弓螺钉置入并椎间融合对邻近节段的影响

MRI measurement of nucleus pulposus volume to assess the influence of unilateral pedicle screw fixation with an interbody fusion cage on adjacent segment

背景:大量的生物力学实验和临床应用研究表明,单侧椎弓根螺钉置入内固定并cage椎间融合不仅能够使脊柱获得即刻固定的稳定性,同时可降低固定节段的刚度。然而目前其对邻近节段椎间盘髓核容积变化的影响还未见报道。目的:应用MRI辅助髓核容积测定评价单侧椎弓根螺钉置入内固定并cage椎间植骨融合修复部分腰椎退变性疾病对固定融合邻近节段椎间盘退变的影响。方法:对34例腰椎间盘脱出症患者行单侧单节段椎弓根螺钉置入内固定加椎间cage植骨融合治疗,其中L_(4-5)节段16例,男9例,女7例。L_5-S_1节段18例,男10例,女8例。术后18个月取出内固定器,随访24-36个月。应用MRI技术,在T2加权像上分别在治疗后6,12,18,30个月测量头侧椎间隙髓核的前后径和宽度,正中矢状位测量髓核高度;X射线片上利用角平分线法测量头侧椎间隙高度。据治疗后髓核体积及椎间隙高度变化评价单侧椎弓根螺钉固定技术对固定邻近节段头侧椎间盘退变的影响。结果与结论:(1)固定L_(4-5)节段临近头侧L_(3-4)节段髓核体积变化:治疗后30个月与治疗前相比较,男性患者有所减少,但差异无显著性意义(P=0.139);而女性患者髓核体积较治疗前有所增加,但差异无显著性意义(P=0.143)。(2)固定L_5-S_1节段临近头侧L_(4-5)节段髓核体积变化:治疗后30个月与治疗前相比,男性患者略有减少,但差异无显著性意义(P=0.096);而女性患者与治疗前相比,治疗后6,12,18,30个月髓核体积均略有增加,但差异无显著性意义(P>0.05)。(3)固定L_(4-5)节段临近头侧L_(3-4)节段椎间隙变化:治疗后30个月,男女性患者椎间隙高度均较治疗前略有减少,但差异无显著性意义(P>0.05)。(4)固定L_5-S_1节段临近头侧L_(4-5)节段椎间隙变化:治疗后30个月随访时,男女性患者椎间隙高度均较治疗前略有减少,但差异无显著性意义(P>0.05)。(5)提示应用单侧单节段椎弓根螺钉置入内固定结合cage椎间植骨融合修复部分腰椎退性性疾病,可对固定融合邻近节段椎间盘退变起有一定的预防作用。

BACKGROUND： A large number of biomechanical studies and clinical application research showed that unilateral pedicle screw fixation with a single cage can not only make the spine to obtain immediate stability, and also reduces the fixed segment stiffness. However, there is not related research on the change of adjacent segment disc nucleus pulposus volume with unilateral pedicle screw. OBJECTIVE： To evaluate the effects of unilateral pedicle screw fixation with a single cage on adjacent segment degeneration for treating lumbar degenerative disease with MRI measurement of lumbar nucleus pulposus volume. METHODS： A total of 34 patients with lumbar disc herniation were treated by posterior lumbar interbody fusion with unilateral pedicle screw fixation with a single cage insertion. There were L_（4-5）segment in 16 patients（9 males and 7 females） and L_5-S_1 segment in 18 patients（10 males and 8 females）. The fixator was taken out at 18 months after surgery. They were followed up for 24 to 36 months. With MRI, the transverse diameter and sagittal diameter of the nucleus pulposus were measured by using T2-weighted images at 6, 12, 18, 30 months after treatment, while the nucleus pulposus height was measured by middle sagittal position. Cephalic intervertebral height was measured with angular bisector method on X-ray films. Effects of unilateral pedicle screw fixation on cephalic intervertebral disc degeneration were evaluated according to nucleus pulposus volume and the intervertebral space height. RESULTS AND CONCLUSION：（1） Nucleus pulposus volume at cephalic L_（3-4） on the fixed L_（4-5） segment was reduced in male patients after 30 months of treatment compared with pre-treatment（P=0.139）, but increased in female patients（P=0.143）.（2） Nucleus pulposus volume at L_（4-5） near to fixed L_5-S_1 segment was slightly reduced in male patients after 30 months of treatment（P=0.096）; nucleus pulposus volume was slightly increased in female patients after 6, 12, 18 and 30 months of treatment（P〉0.05）.（3） Disc space height at cephalic L_（3-4） near to L_（4-5） segment was diminished in male and female patients at 30 months of treatment（P〉0.05）.（4） Disc space height at cephalic L_（4-5） near to L_5-S_1 segment was slightly reduced in male and female patients compared with pre-treatment（P〉0.05）.（5） Unilateral pedicle screw with a single cage could effectively prevent adjacent segment degeneration in treatment of partial lumbar intervertebral degenerative disease.