Department of Orthopaedics, University of Minnesota, Minneapolis, MN 55454, USA.
Spine (Phila Pa 1976). 2012 Jan 15;37(2):E119-25. doi: 10.1097/BRS.0b013e3182257cae.
Human cadaveric study.
The objective of the study was to determine the accuracy of intraoperative O-arm images in determining pedicle screw position using open dissection as the gold standard.
Pedicle screws are widely used in the treatment of various spinal disorders. Postoperative computed tomographic scans are the imaging gold standard to detect pedicle screw malposition. However, a second procedure is necessary if such malpositioned screws have to be revised. The O-arm is an intraoperative scanner that allows revision of a screw without having to return the patient to the operating room for a separate procedure. No previous studies have looked at the accuracy of intraoperative O-arm images in determining pedicle screw position.
This factorial validation study utilized 9 cadavers in a comparison of intraoperative O-arm images and the dissection gold standard. Four hundred sixteen screws were inserted using 3-dimensional image (O-arm) guidance from C2 to S1. The screw positions were randomized into 3 groups: "IN" (fully contained within the pedicle), "OUT-lateral," or "OUT-medial." After screw insertion, O-arm images were obtained and reviewed in a blinded fashion by 3 independent observers. Dissection identified the true position of the screws. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using dissection results as the gold standard. The interobserver reliability was also determined.
The overall accuracy, specificity, sensitivity, PPV, and NPV of O-arm images for the thoracic and lumbar spine were 73%, 76%, 71%, 74%, and 72%, respectively. Accuracy of surgeon perception in the cervical spine was significantly less than in the thoracic and lumbosacral spine. There was substantial interobserver agreement between the 3 readers.
Intraoperative O-arm images accurately detect significant pedicle screw violations in the thoracic and lumbosacral spine but are less accurate for the cervical spine.
人体尸体研究。
本研究的目的是确定术中 O 臂图像在使用开放式解剖作为金标准确定椎弓根螺钉位置的准确性。
椎弓根螺钉广泛用于治疗各种脊柱疾病。术后计算机断层扫描是检测椎弓根螺钉位置不当的影像学金标准。然而，如果需要修正这些位置不当的螺钉，则需要进行第二次手术。O 臂是一种术中扫描仪，可在无需将患者返回手术室进行单独手术的情况下修正螺钉。以前没有研究探讨过术中 O 臂图像在确定椎弓根螺钉位置方面的准确性。
这项析因验证研究在术中 O 臂图像与解剖金标准的比较中使用了 9 具尸体。使用 3 维图像（O 臂）引导从 C2 到 S1 插入了 416 个螺钉。螺钉位置随机分为 3 组：“IN”（完全包含在椎弓根内）、“OUT-外侧”或“OUT-内侧”。插入螺钉后，以盲法获得 O 臂图像，并由 3 位独立观察者进行回顾。解剖确定了螺钉的真实位置。使用解剖结果作为金标准，计算了特异性、敏感性、阳性预测值（PPV）和阴性预测值（NPV）。还确定了观察者间的可靠性。
胸腰椎 O 臂图像的总体准确性、特异性、敏感性、PPV 和 NPV 分别为 73%、76%、71%、74%和 72%。颈椎手术医生感知的准确性明显低于胸腰椎。3 位读者之间存在大量的观察者间一致性。
术中 O 臂图像可准确检测胸腰椎的显著椎弓根螺钉侵犯，但对颈椎的准确性较低。
