Matsukawa Keitaro, Abe Yuichiro, Mobbs Ralph Jasper
Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Tokyo, Japan.
Department of Orthopaedic Surgery, Wajokai Eniwa Hospital, Eniwa, Japan.
Spine Surg Relat Res. 2021 Mar 10;5(6):418-424. doi: 10.22603/ssrr.2020-0221. eCollection 2021.
The sacral-alar-iliac (SAI) screw technique is becoming popular for sacropelvic fixation. However, appropriately placing SAI screws is technically demanding because of a narrow safe corridor and the risk of neurovascular/visceral injuries. Recently, a three-dimensional patient-specific template guiding technique for pedicle screw placement has been considered a promising method to improve accuracy and safety. The objective of the present study was to investigate the accuracy of SAI screw placement with a patient-specific template guide using cadaveric and prospective clinical pilot studies.
Three-dimensional planning of SAI screw placement, including entry point, screw trajectory, length, and diameter, was performed using a computer simulation software. Then, three-dimensional printed patient-specific template guides were created based on the plan. Firstly, a total of 12 SAI screws were placed for 6 cadaveric specimens using the guides. Next, in a prospective clinical trial, a total of 20 SAI screws were placed for 10 consecutively enrolled patients. The safety and accuracy of screw placement were analyzed using postoperative computed tomography by the evaluation of any cortical breach and measurement of screw deviations between the planned and actual screw positions.
All the screws showed no perforation. In the cadaveric study, the mean horizontal and vertical deviations from the planned screw position at the entry point were 1.40±1.21 mm and 1.34±1.09 mm, respectively. The mean angular deviations in the sagittal and transverse planes were 1.68°±1.24° and 1.53°±1.06°, respectively. The results of the clinical study showed comparable accuracy with those of the cadaveric study, except for the vertical deviation at the entry point (=0.048).
This is the first study to evaluate the feasibility and accuracy of using a patient-specific template guide for SAI screw placement. This technique could become an effective solution to achieve accurate screw placement.
骶骨-翼-髂骨（SAI）螺钉技术在骶骨盆固定中越来越受欢迎。然而，由于安全通道狭窄以及存在神经血管/内脏损伤风险，正确放置SAI螺钉在技术上具有挑战性。最近，一种用于椎弓根螺钉置入的三维个体化模板引导技术被认为是提高准确性和安全性的一种有前景的方法。本研究的目的是通过尸体和前瞻性临床试点研究，探讨使用个体化模板引导进行SAI螺钉置入的准确性。
使用计算机模拟软件进行SAI螺钉置入的三维规划，包括进针点、螺钉轨迹、长度和直径。然后，根据该规划制作三维打印的个体化模板引导器。首先，使用引导器为6个尸体标本共置入12枚SAI螺钉。接下来，在一项前瞻性临床试验中，为10例连续入组的患者共置入20枚SAI螺钉。术后通过计算机断层扫描评估螺钉置入的安全性和准确性，评估是否有皮质穿透以及测量计划和实际螺钉位置之间的螺钉偏差。
所有螺钉均未出现穿孔。在尸体研究中，进针点处螺钉实际位置与计划位置的平均水平和垂直偏差分别为1.40±1.21mm和1.34±1.09mm。矢状面和横断面的平均角度偏差分别为1.68°±1.24°和1.53°±1.06°。临床研究结果显示，除进针点处的垂直偏差（=0.048）外，与尸体研究结果的准确性相当。
这是第一项评估使用个体化模板引导进行SAI螺钉置入的可行性和准确性的研究。该技术可能成为实现准确螺钉置入的有效解决方案。
