Service de Chirurgie du Rachis, Hôpitaux Universitaires de Strasbourg, 1, Avenue Molière, 67200, Strasbourg, France.
Service de Radiologie Interventionelle, Hôpitaux Universitaires de Strasbourg, 1, place de l'hôpital, 67000, Strasbourg, France.
Surg Radiol Anat. 2021 Jun;43(6):843-853. doi: 10.1007/s00276-020-02673-7. Epub 2021 Jan 15.
The two-dimensional fluoroscopic method of percutaneous pedicle screw instrumentation has been clinically described as reliable method in the caudal thoracic and lumbosacral spine. Its accuracy has not been clearly reported in the cranial thoracic spine. The aim of this in vitro study was to investigate percutaneous pedicle screw placement accuracy according to pedicle dimensions and vertebral levels.
Six fresh-frozen human specimens were instrumented with 216 screws from T1 to S1. Pedicle isthmus widths, heights, transversal pedicles and screws were measured on computed tomography. Pedicle cortex violation ≥ 2 mm was defined as screw malposition.
The narrowest pedicles were at T3-T5. A large variability between transversal pedicle axes and percutaneous pedicle screw was present, depending on the spinal level. Screw malposition rates were 36.1% in the cranial thoracic spine (T1-T6), 16.7% in the caudal thoracic spine (T7-T12), and 6.9% in the lumbosacral spine (L1-S1). The risk for screw malposition was significantly higher at cranial thoracic levels compared to caudal thoracic (p = 0.006) and lumbosacral (p < 0.0001) levels. Cortex violation ≥ 2 mm was constantly present if the pedicle width was < 4.8 mm.
Percutaneous pedicle screw placement appears safe in the caudal thoracic and lumbosacral spine. The two-dimensional fluoroscopic method has a limited reliability above T7 because of smaller pedicle dimensions, difficulties in visualizing radiographic pedicle landmarks and kyphosis.
经皮椎弓根螺钉内固定的二维透视法已在胸腰段和腰骶段脊柱的临床中被描述为可靠的方法。但其在颅胸段脊柱中的准确性尚未明确报道。本体外研究的目的是根据椎弓根的尺寸和椎体的水平来研究经皮椎弓根螺钉的放置准确性。
6 个新鲜冷冻的人体标本从 T1 到 S1 共进行了 216 个螺钉的置入。在 CT 上测量椎弓根峡部的宽度、高度、横突和螺钉。椎弓根皮质侵犯≥2mm 定义为螺钉位置不当。
最窄的椎弓根位于 T3-T5。根据脊柱的水平，横突轴线和经皮椎弓根螺钉之间存在很大的差异。颅胸段（T1-T6）螺钉位置不当的发生率为 36.1%，胸腰段（T7-T12）为 16.7%，腰骶段（L1-S1）为 6.9%。颅胸段的螺钉位置不当风险明显高于胸腰段（p=0.006）和腰骶段（p<0.0001）。如果椎弓根宽度<4.8mm，则皮质侵犯≥2mm 始终存在。
经皮椎弓根螺钉置入在胸腰段和腰骶段是安全的。由于椎弓根尺寸较小、在影像学上难以观察到椎弓根的解剖标志和存在脊柱后凸，二维透视法在 T7 以上的可靠性有限。
