Infusa A, An H S, Glover J M, McGrady L, Lim T H, Riley L H
Department of Orthopaedic Surgery, Medical College of Wisconsin, Milwaukee, USA.
Spine (Phila Pa 1976). 1996 Oct 1;21(19):2218-23. doi: 10.1097/00007632-199610010-00008.
A cadaveric study was performed to analyze the changes of foraminal dimensions of the lumbar spine and also to estimate the amount of foraminal distraction, achieved with pedicle screw instrumentation, that will create the greatest improvement in foraminal dimensions.
To establish the ideal amount of lumbar foraminal distraction using pedicle screw instrumentation and to investigate the changes of adjacent segments and lumbar lordosis with distraction maneuvers.
In patients undergoing fusions and instrumentation for foraminal stenosis, distraction of the lumbar spine may improve the dimensions of the intervertebral foramen. Results of previous studies have shown that anterior interbody distraction of the lumbar spine significantly increased the space in the lumbar foramen. No previous study has assessed the ideal amount of distraction, changes in the adjacent segments, or the effect on lumbar lordosis using posterior pedicle screw instrumentation.
Six fresh frozen human cadaveric spines from 15 to the sacrum were used. The ISOLA instrumentation system (Acromed Inc., Cleveland, OH) was applied using pedicle screws at L4, L5, and S1, L4-L5 and L5-S1 rods were contoured to the same degree of lumbar lordosis as in the specimen. The spine was potted in the upright position with the sacrum secured in the mold, and an axial load of 40 pounds was applied to the specimen. Radiographs were used to measure the posterior disc height, foraminal height, foraminal area, and lumbar lordosis. Two mm, 4 mm, 6 mm, 8 mm, and 10 mm of single level distraction were added to L4-L5 and L5-S1. The dimensions of the specimen were digitized and calculated after each distraction.
The posterior disc height, foraminal height and foraminal area increased with distraction. The greatest incremental change in the foraminal area was noted at 6 mm of distraction. The L4-L5 foraminal area increased 22.6% at 6 mm of L4-L5 distraction, and the L5-S1 foraminal area increased 39.2% at 6 mm of L5-S1 distraction. With distraction above 6 mm, the foraminal change plateaued. The greatest decrease in lumbar lordosis was only 4.6 degrees and occurred at 10 mm of distraction. There was no significant effect of distraction on the foramina of adjacent levels.
Posterior distraction using pedicle screws increased foraminal dimensions. The ideal amount of distraction on the rod, or the minimal amount of distraction necessary for improving foraminal dimensions, may be 6 mm using pedicle screw instrumentation.
进行了一项尸体研究，以分析腰椎椎间孔尺寸的变化，并估计椎弓根螺钉内固定实现的椎间孔撑开量，该撑开量将使椎间孔尺寸得到最大改善。
确定使用椎弓根螺钉内固定的理想腰椎椎间孔撑开量，并研究撑开操作对相邻节段和腰椎前凸的影响。
在因椎间孔狭窄接受融合和内固定手术的患者中，腰椎撑开可能会改善椎间孔尺寸。先前的研究结果表明，腰椎前路椎间撑开显著增加了腰椎椎间孔的空间。此前尚无研究使用后路椎弓根螺钉内固定评估理想的撑开量、相邻节段的变化或对腰椎前凸的影响。
使用6具从第15节段至骶骨的新鲜冷冻人体尸体脊柱。在L4、L5和S1处使用椎弓根螺钉应用ISOLA内固定系统（Acromed公司，俄亥俄州克利夫兰），L4-L5和L5-S1的棒材塑形为与标本相同程度的腰椎前凸。将脊柱以直立姿势固定在模具中，骶骨固定在模具内，对标本施加40磅的轴向载荷。使用X线片测量椎间盘后高度、椎间孔高度、椎间孔面积和腰椎前凸。在L4-L5和L5-S1处分别进行2mm、4mm、6mm、8mm和10mm的单节段撑开。每次撑开后对标本的尺寸进行数字化处理和计算。
随着撑开，椎间盘后高度、椎间孔高度和椎间孔面积增加。在撑开6mm时，椎间孔面积的增加最为显著。L4-L5撑开6mm时，L4-L5椎间孔面积增加22.6%，L5-S1撑开6mm时，L5-S1椎间孔面积增加39.2%。撑开超过6mm时，椎间孔变化趋于平稳。腰椎前凸的最大减小仅为4.6度，且发生在撑开10mm时。撑开对相邻节段的椎间孔没有显著影响。
使用椎弓根螺钉进行后路撑开可增加椎间孔尺寸。使用椎弓根螺钉内固定时，棒材上理想的撑开量，即改善椎间孔尺寸所需的最小撑开量可能为6mm。
