TOMOGRAPHIC STUDY OF THE S2-ALAR-ILIAC SCREW TECHNIQUE IN BRAZILIAN MEN

ABSTRACT Objective The use of pedicle screws was a milestone for modern spinal surgery. This type of fixation, due to its superior biomechanics, gave greater fixation power, greater capacity to withstand the pulling forces and, therefore, greater stability and lower rates of pseudoarthrosis. Fixation of the lumbosacral junction, even with the development of these new implants, remains a challenge mainly because the considerable rates of pseudoarthrosis. The use of iliac screws solves the biomechanical difficulties. However, its use shows high rates of surgical wound problems. The S2-Alar-Iliac screw (S2AI) came as a solution to these complications. The lack of studies about anatomical and anthropometric parameters in the Brazilian population justifies the study. Methods Eleven hip tomographies of Brazilian adult males were analyzed by four evaluators. The right and left sides were considered. In each patient, measurements were made of greater and shorter bone length, greater and smaller bone diameter, distance from the entry point to the skin, sagittal and axial angles related to the hypothetical insertion of an S2AI screw and compared to the same measurements obtained with the iliac screw. Results The mean bone length was 136.7 mm, the greatest bone diameter was 24.8 mm, the smallest bone diameter was 19.7 mm and the distance from the screw to the skin was 42.1 mm for the S2AI screw. Conclusions The obtained data present an average of the sample that can be useful in the decision of the surgical technique in the studied group. Level of evidence I; Diagnostic Studies (Anatomical Investigation).摘要 研究目的 椎弓根螺钉的应用是现代脊柱外科的里程碑事件。此类固定方式凭借优异的生物力学特性，具备更强的固定强度与抗牵拉载荷能力，因此可提供更高的稳定性，并降低假关节形成率。尽管新型植入物不断发展，腰骶结合部的固定仍为临床难题，其假关节形成率仍居高不下。髂骨螺钉可解决上述生物力学困境，但该术式的手术切口并发症发生率较高。S2骶骨翼髂骨螺钉（S2-Alar-Iliac screw, S2AI）的问世为解决此类并发症提供了可行方案。目前针对巴西人群的解剖学与人体测量学参数研究仍较为匮乏，故而开展本项研究。 研究方法 本研究纳入11例巴西成年男性的髋关节CT扫描影像，由4名评估者分别对双侧（左侧、右侧）数据进行分析。针对每位患者，测量其骨最大长度、骨最小长度、骨最大直径、骨最小直径、螺钉进针点至皮肤的距离，以及与S2AI螺钉假想置入相关的矢状位与轴位角度，并将上述指标与髂骨螺钉的对应测量结果进行对比。 研究结果 S2AI螺钉的平均骨长度为136.7mm，骨最大直径为24.8mm，骨最小直径为19.7mm，螺钉至皮肤的距离为42.1mm。 研究结论 本研究获取的样本平均数据可为该研究人群的手术术式选择提供参考依据。 证据等级：I级；诊断性研究（解剖学调查）。