SUMMARY OF BACKGROUND DATA

Pedicle screws are commonly placed with lumbar/lumbosacral fusions. Triggered electromyography (tEMG), which employs the application of electrical current between the screw and a complementary anode to determine thresholds of conduction, may be utilized to confirm the safe placement of such implants. While previous research has established clinical thresholds associated with safe screw placement, there is variability in clinical practice of anode placement which could lead to unreliable measurements.

PURPOSE

To determine the variance in pedicle screw stimulation thresholds when using four unique anode locations (ipsilateral/contralateral and paraspinal/gluteal relative to tested pedicle screws).

STUDY DESIGN

Prospective cohort study. Tertiary medical center.

PATIENT SAMPLE

Twenty patients undergoing lumbar/lumbosacral fusion with pedicle screws using tEMG

OUTCOME MEASURES

tEMG stimulation return values are used to assess varied anode locations and reproducibility based on anode placement.

METHODS

Measurements were assessed across node placement in ipsilateral/contralateral and paraspinal/gluteal locations relative to the screw being assessed. R² coefficients of correlation were determined, and variances were compared with F-tests.

RESULTS

A total of 94 lumbosacral pedicle screws from 20 patients were assessed. Repeatability was verified using two stimulations at each location for a subset of the screws with an R² of 0.96. Comparisons between the four anode locations demonstrated R² values ranging from 0.76 to 0.87. F-tests comparing thresholds between each anode site demonstrated all groups not to be statistically different.

CONCLUSION

The current study, a first-of-its-kind formal evaluation of anode location for pedicle screw tEMG testing, demonstrated very strong repeatability and strong correlation with different locations of anode placement. These results suggest that there is no need to change the side of the anode for testing of left versus right screws, further supporting that placing an anode electrode into gluteal muscle is sufficient and will avoid a sharp ground needle in the surgical field.

中文翻译：

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腰骶椎融合手术中阳极位置对椎弓根螺钉测试的影响

背景数据概要

椎弓根螺钉通常与腰椎/腰骶融合术一起放置。触发肌电图 (tEMG) 在螺钉和互补阳极之间应用电流来确定传导阈值，可用于确认此类植入物的安全放置。虽然之前的研究已经建立了与安全螺钉放置相关的临床阈值，但阳极放置的临床实践存在差异，这可能导致测量不可靠。

目的

确定使用四个独特的阳极位置（相对于测试的椎弓根螺钉的同侧/对侧和椎旁/臀部）时椎弓根螺钉刺激阈值的变化。

学习规划

前瞻性队列研究。三级医疗中心。

患者样本

使用 tEMG 进行椎弓根螺钉腰椎/腰骶融合术的 20 名患者

结果测量

tEMG 刺激返回值用于评估不同的阳极位置和基于阳极放置的再现性。

方法

相对于被评估的螺钉，测量在同侧/对侧和脊柱旁/臀部位置的节点放置进行评估。确定了R ²相关系数，并用 F 检验比较了方差。

结果

对来自 20 名患者的 94 颗腰骶椎弓根螺钉进行了评估。^{对于 R 2}为 0.96 的螺钉子集，在每个位置使用两次刺激来验证可重复性。四个阳极位置之间的比较表明 R ²值范围为 0.76 至 0.87。比较每个阳极站点之间的阈值的 F 测试表明所有组在统计上没有差异。

结论

目前的研究是对椎弓根螺钉 tEMG 测试阳极位置的首次正式评估，证明了非常强的可重复性和与不同阳极放置位置的强相关性。这些结果表明，无需改变阳极的侧面来测试左螺钉和右螺钉，进一步支持将阳极电极放入臀肌中就足够了，并且会避免在手术区域使用锋利的接地针。