Spinal fixation procedures are currently limited by the rigidity of the existing instruments and pedicle screws leading to fixation failures and rigid pedicle screw pull out. Leveraging our recently developed Concentric Tube Steerable Drilling Robot (CT-SDR) in integration with a robotic manipulator, to address the aforementioned issue, here we introduce the transformative concept of Spatial Spinal Fixation (SSF) using a unique Flexible Pedicle Screw (FPS). The proposed SSF procedure enables planar and out-of-plane placement of the FPS throughout the full volume of the vertebral body. In other words, not only does our fixation system provide the option of drilling in-plane and out-of-plane trajectories, it also enables implanting the FPS inside linear (represented by an I-shape) and/or non-linear (represented by J-shape) trajectories. To thoroughly evaluate the functionality of our proposed robotic system and the SSF procedure, we have performed various experiments by drilling different I-J and J-J drilling trajectory pairs into our custom-designed L3 vertebral phantoms and analyzed the accuracy of the procedure using various metrics.

翻译：目前脊柱固定手术受限于现有器械和椎弓根螺钉的刚性，常导致固定失败及刚性椎弓根螺钉拔出。为应对上述问题，本研究结合新近研发的同心管可转向钻孔机器人与机械臂操作系统，提出采用独特柔性椎弓根螺钉的空间脊柱固定这一变革性理念。所提出的SSF方案支持在椎体全容积范围内实现FPS的平面与离面置入。换言之，本固定系统不仅支持平面与离面钻孔轨迹的规划，还能实现FPS在线性轨迹（以I形表示）和/或非线性轨迹（以J形表示）内的植入。为全面评估所提机器人系统及SSF方案的功能性，我们通过在定制设计的L3椎体仿体上钻削多组I-J与J-J钻孔轨迹对，并采用多种度量指标分析手术精度，开展了系列实验验证。