CT评估腰骶段后路椎弓根置钉的准确性研究

Retrospective study on the CT evaluation of accuracy of pedicle screw placement in posterior lumbosacral instrumentation

目的统计分析L4、L5及S1后路椎弓根置钉准确性，并探讨导致椎弓根穿透的原因。方法回顾性分析2014年1月至2014年12月符合纳入及排除标准、接受腰骶椎后路椎弓根钉一棒系统固定手术的患者共293例，L4节段219例，L5节段270例及S，节段95例。术后24-48h内均行腰骶椎CT平扫及重建，由2名专业人员评估L4、L5和S1节段椎弓根螺钉在椎弓根内的位置。对于穿透椎弓根侧壁的螺钉，记录其穿透位置与程度，统计螺钉在腰骶椎各节段的穿透情况，分析导致椎弓根穿透的相关因素。对各医院间椎弓根螺钉穿透率进行统计分析。对所有患者均行术后随访观察，记录所有可能因椎弓根螺钉穿透而导致的并发症。结果293例患者共置入椎弓根螺钉1166枚，其中穿透椎弓根侧壁的螺钉280枚。L4节段穿透率为28．9％（126／436），L5节段为24．5％（132／539），S1节段为11．5％（22／191）。椎弓根螺钉在L5和L4节段穿透率的差异无统计学意义；但均高于S1节段，差异均有统计学意义。椎弓根穿透位置统计结果显示，L4节段内下缘穿透率为58．7％（74／126），L5节段为75％（99／132），S1节段为86．4％（19／22）；与L4节段相比，L5和S1椎弓根螺钉穿透更集中于椎弓根内下缘。穿透严重程度统计结果显示，L4节段高危穿透率（Ⅲ级、Ⅳ级）为6．3％（8／126），L，节段为14．4％（19／132），S1节段为36．4％（8／22）；L5和S1节段达到严重破损的比例均明显高于L。节段。3所医院间穿透率的差异有统计学意义，而各医院椎弓根螺钉穿透节段、穿透程度以及穿透位置的特点与总体结果趋于一致。椎弓根穿透的病例中9例发生脑脊液漏，2例神经损伤表现。结论L5与L4节段具有同样的高穿透率，L5和S1节段达到高危穿透的比例更高，且更多地集中于椎弓根内下缘。低级别医院发生椎弓根螺钉穿透的比例及相关并发症更高。

Objectives To evaluate the accuracy of posterior pedicle screw placement in a multi-centric retrospective clinical study and analyze the potential reasons of pedicle breaches. Methods From January 2014 to December 2014, 293 patients with conventional posterior pedicle screw instrumentation up to inclusion and exclusion criteria were recruited from 3 different hospitals. The operative levels included L4 in 219 cases, L5 in 270 cases and S1 in 95 cases. The screw positions in the pedicles were verified by 2 professional observers independently under computed tomography reconstruction within 24 hours to 48 hours postoperatively. The locations and grades of breached pedicles were recorded in each segment and related factors were analyzed. Pedicle breach rates in 3 hospitals were stratified and analyzed as welh All patients were followed up and neurological deficits as well as other postoperative complications were registered. Results There were 280 pedicle breaches in a total of 1166 instrumented pedicles of 293 patients. The breach rates in different levels were listed as 29.0% （126/436） in L4, 24.5% （132/539） in L5 and 11.5% （22/191） in S1. There were no significant differences in pedicle breach rates between L4 and Ls, while the breach rates in L4 and L5 were both significantly higher than those in St. For severe violation from L4 to St, 6.3% （8/126）, 14.4% （19/ 132） and 36.4% （8/22） were confirmed respectively. The incidences of high risk pedicle breach （grade III, grade IV） of L5 and S1 were significantly higher than those of L4. Furthermore, the inferomedial breach rates quantified from L4 to S1 were 58.7% （74/126）, 75% （99/132）, 86.4% （19/22） respectively. The breach rates in the inferomedial wall of the L5, S1 pedicles were statistically higher than those of L4. Pediele breach rates among 3 hospitals varied while the characteristics of the locations, the grades and the segments of breached pedicles were similar to overall results in each hospital. There were 9 eases of eerebrospinal fluid leakage and 2 cases of transient nerve root injuries. Conclusion There are no significant differences in pedicle breach rates between L4 and L5. However, pedicle breach rates in L4 and L5 are statistically higher than those in S1. The incidence of high risk pedicle breach and inferomedial wall breach of L5 and S1 are significantly higher than that of L4. In addition, the incidences of pedicle breaches and related complications occurred more in lower-level hospitals.