Guo Jing, Guo Lianjin, Gao Juzhou, Ling Qinjie, Yin Zhixun, He Erxing
Spine Surgery, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
Guangzhou Orthopaedic Institute, Guangzhou, China.
BMC Musculoskelet Disord. 2017 May 5;18(1):180. doi: 10.1186/s12891-017-1537-x.
Significant prominence of iliac crests with a deep seated L5 vertebra can potentially interfere with the screw trajectory when placing percutaneous pedicle screws (PPS) at the lumbosacral segment. The objective of this study was to investigate the influence of L5 position in relation to the iliac crests on the accuracy of percutaneous placement of lumbosacral pedicle screws.
From Oct 2012 to Sep 2014, 54 patients who underwent PPS placement at L5-S1 segment were recruited. Patients were divided into 2 groups: the L5-Seated Group (L5-S Group, n = 34) including patients with intercrest lines passing through the L4 vertebra or L4/5 intervertebral disc; whereas the L5-Non-Seated Group (L5-NS Group, n = 20) including patients with intercrest lines passing through the L5 vertebra. Postoperative computerized tomography was obtained in all patients, and PPS accuracy was evaluated by grading pedicle breach (Grade 0, no breach; Grade 1, ≤2mm; Grade 2, >2mm without neurological compromise; Grade 3, with complications). Screw convergence angle (SCA), defined as the angle subtended by the screw axis and vertebral midline, was also recorded.
In the L5-S Group, 82.4% (56/68) screws were measured as Grade 0 at L5, and 66.2% (45/68) were Grade 0 at S1; meanwhile, in the L5-NS Group, 77.5% (31/40) and 75.0% (30/40) screws were Grade 0 at L5 and S1, respectively. Misplacement rate was numerically higher at S1 in the L5-S Group (P > 0.05). There were significantly more medial pedicle violations at S1 in the L5-S Group as compared to the L5-NS Group (25.0% vs 7.5%, P = 0.024). No statistical difference was found in L5 SCA between the 2 groups (L5-S Group 23.7° ± 7.4° vs L5-NS Group 23.4° ± 10.6°, P = 0.945); however, S1 SCA was significantly smaller in the L5-S Group (14.7° ± 5.8°) when compared with the L5-NS Group (20.8° ± 5.2°) (P = 0.036).
A deep seated L5 vertebra with respect to the iliac crests might compromise the accuracy of PPS placement at S1 vertebra. Severe iliac prominence may interfere with the screw trajectory and limit the medial angulation of pedicle screw for percutaneous S1 fixation.
髂嵴明显突出且L5椎体位置较深时，在腰骶段置入经皮椎弓根螺钉（PPS）可能会干扰螺钉的轨迹。本研究的目的是探讨L5相对于髂嵴的位置对腰骶椎弓根螺钉经皮置入准确性的影响。
2012年10月至2014年9月，招募了54例行L5-S1节段PPS置入术的患者。患者分为2组：L5低位组（L5-S组，n = 34），包括髂嵴连线经过L4椎体或L4/5椎间盘的患者；而L5非低位组（L5-NS组，n = 20），包括髂嵴连线经过L5椎体的患者。所有患者术后均行计算机断层扫描，并通过对椎弓根穿破情况进行分级（0级，无穿破；1级，≤2mm；2级，>2mm且无神经损伤；3级，有并发症）来评估PPS的准确性。还记录了螺钉汇聚角（SCA），定义为螺钉轴线与椎体中线所成的角度。
在L5-S组中，L5节段82.4%（56/68）的螺钉测量为0级，S1节段66.2%（45/68）为0级；同时，在L5-NS组中，L5和S1节段分别有77.5%（31/40）和75.0%（30/40）的螺钉为0级。L5-S组S1节段的误置率在数值上更高（P>0.05）。与L5-NS组相比，L5-S组S1节段的内侧椎弓根侵犯明显更多（25.0%对7.5%，P = 0.024）。两组间L5的SCA无统计学差异（L5-S组23.7°±7.4°对L5-NS组23.4°±10.6°，P = 0.945）；然而，与L5-NS组（20.8°±5.2°）相比，L5-S组S1的SCA明显更小（14.7°±5.8°）（P = 0.036）。
相对于髂嵴，L5椎体位置较深可能会影响S1椎体PPS置入的准确性。严重的髂嵴突出可能会干扰螺钉轨迹，并限制经皮S1固定时椎弓根螺钉的内侧成角。
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