基于增强现实的导航可提高椎弓根螺钉插入的精度。

BACKGROUND: Precise insertion of pedicle screws is important to avoid injury to closely adjacent neurovascular structures. The standard method for the insertion of pedicle screws is based on anatomical landmarks (free-hand technique). Head-mounted augmented reality (AR) devices can be used to guide instrumentation and implant placement in spinal surgery. This study evaluates the feasibility and precision of AR technology to improve precision of pedicle screw insertion compared to the current standard technique. METHODS: Two board-certified orthopedic surgeons specialized in spine surgery and two novice surgeons were each instructed to drill pilot holes for 40 pedicle screws in eighty lumbar vertebra sawbones models in an agar-based gel. One hundred and sixty pedicles were randomized into two groups: the standard free-hand technique (FH) and augmented reality technique (AR). A 3D model of the vertebral body was superimposed over the AR headset. Half of the pedicles were drilled using the FH method, and the other half using the AR method. RESULTS: The average minimal distance of the drill axis to the pedicle wall (MAPW) was similar in both groups for expert surgeons (FH 4.8 ± 1.0 mm vs. AR 5.0 ± 1.4 mm, p = 0.389) but for novice surgeons (FH 3.4 mm ± 1.8 mm, AR 4.2 ± 1.8 mm, p = 0.044). Expert surgeons showed 0 primary drill pedicle perforations (PDPP) in both the FH and AR groups. Novices showed 3 (7.5%) PDPP in the FH group and one perforation (2.5%) in the AR group, respectively (p > 0.005). Experts showed no statistically significant difference in average secondary screw pedicle perforations (SSPP) between the AR and the FH set 6-, 7-, and 8-mm screws (p > 0.05). Novices showed significant differences of SSPP between most groups: 6-mm screws, 18 (45%) vs. 7 (17.5%), p = 0.006; 7-mm screws, 20 (50%) vs. 10 (25%), p = 0.013; and 8-mm screws, 22 (55%) vs. 15 (37.5%), p = 0.053, in the FH and AR group, respectively. In novices, the average optimal medio-lateral convergent angle (oMLCA) was 3.23° (STD 4.90) and 0.62° (STD 4.56) for the FH and AR set screws (p = 0.017), respectively. Novices drilled with a higher precision with respect to the cranio-caudal inclination angle (CCIA) category (p = 0.04) with AR. CONCLUSION: In this study, the additional anatomical information provided by the AR headset superimposed to real-world anatomy improved the precision of drilling pilot holes for pedicle screws in a laboratory setting and decreases the effect of surgeon's experience. Further technical development and validations studies are currently being performed to investigate potential clinical benefits of the herein described AR-based navigation approach.

背景：准确插入椎弓根螺钉对于避免邻近的神经血管结构损伤很重要。椎弓根螺钉的标准插入方法是基于解剖学标志（徒手技术）。头戴式增强现实（AR）设备可用于引导脊柱手术中的器械和植入物放置。本研究评估了 AR 技术相对于当前标准技术提高椎弓根螺钉插入精度的可行性和精度。

方法：两位专门从事脊柱外科的认证骨科医生和两位新手外科医生分别指导在琼脂基凝胶中的 80 个腰椎模型中为 40 个椎弓根螺钉钻导孔。160 个椎弓根随机分为两组：标准徒手技术（FH）和增强现实技术（AR）。将椎体的 3D 模型叠加在 AR 耳机上。一半的椎弓根用 FH 方法钻孔，另一半用 AR 方法钻孔。

结果：对于专家外科医生，两组的钻头轴到椎弓根壁的最小距离（MAPW）平均值相似（FH：4.8±1.0mm vs. AR：5.0±1.4mm，p=0.389），但对于新手外科医生，FH 组为 3.4mm±1.8mm，AR 组为 4.2mm±1.8mm，p=0.044。专家外科医生在 FH 和 AR 组中均未出现主要钻头椎弓根穿孔（PDPP）。新手外科医生在 FH 组中有 3 个（7.5%）PDPP，在 AR 组中有 1 个（2.5%），p>0.005。专家外科医生在 AR 和 FH 设定的 6、7 和 8mm 螺钉之间的平均次要螺钉椎弓根穿孔（SSPP）之间没有统计学上的显著差异（p>0.05）。新手外科医生在大多数组之间的 SSPP 存在显著差异：6mm 螺钉，18（45%）与 7（17.5%），p=0.006；7mm 螺钉，20（50%）与 10（25%），p=0.013；8mm 螺钉，22（55%）与 15（37.5%），p=0.053，分别在 FH 和 AR 组中。在新手外科医生中，FH 和 AR 设定螺钉的平均最佳中侧会聚角（oMLCA）分别为 3.23°（STD 4.90）和 0.62°（STD 4.56），p=0.017。新手外科医生在 AR 辅助下钻导孔时，钻头的颅尾倾斜角（CCIA）精度更高（p=0.04）。

结论：在这项研究中，通过将 AR 耳机叠加到真实解剖结构上提供的附加解剖学信息提高了在实验室环境中椎弓根螺钉导孔钻孔的精度，并降低了外科医生经验的影响。目前正在进行进一步的技术开发和验证研究，以研究本文描述的基于 AR 的导航方法的潜在临床益处。