de Kater Esther P, Jager David J, Breedveld Paul, Sakes Aimée
Bio-Inspired Technology Group, Faculty of Mechanical Engineering, Department of BioMechanical Engineering, Delft University of Technology, Delft, The Netherlands.
Department of Electronic and Mechanical Support Division, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, Delft, The Netherlands.
PLoS One. 2024 Dec 19;19(12):e0315629. doi: 10.1371/journal.pone.0315629. eCollection 2024.
Pedicle screws have long been established as the gold standard for spinal bone fixation. However, their fixation strength can be compromised in cases of low bone density, particularly in osteoporotic bone, due to the reliance on a micro-shape lock between the screw thread and the surrounding bone. To address this challenge, we propose augmenting conventional pedicles screws with a curved compliant anchor. This anchor integrates a curved super-elastic nitinol rod that is advanced through a canulated pedicle screw, forming a macro-shape lock within the vertebral body to aid the fixation strength. Both placement safety and fixation strength of this novel spinal bone anchor were validated on tissue phantoms (Sawbones). The radius of the curved compliant anchor's path demonstrates high precision while exhibiting strong dependence on the bone density in which the anchor is placed. When the curved compliant anchor is combined with a conventional pedicle screw, the mean maximum pull-out force elevated to 290 N, marking a 14% enhancement in pull-out resistance compared to using pedicle screw alone. Further augmentation with multiple curved compliant anchors holds promise for even greater fixation. The application of a curved compliant spinal bone anchor offers a promising means of increasing the fixation strength of pedicles screws, which is especially relevant in challenging clinical scenarios such a patient suffering from osteoporosis.
椎弓根螺钉长期以来一直被视为脊柱骨固定的金标准。然而，由于其固定强度依赖于螺钉螺纹与周围骨骼之间的微观形状锁定，在骨密度较低的情况下，尤其是骨质疏松性骨中，其固定强度可能会受到影响。为应对这一挑战，我们提出用一种弯曲的柔性锚固件增强传统椎弓根螺钉。这种锚固件集成了一根弯曲的超弹性镍钛诺棒，该棒穿过空心椎弓根螺钉，在椎体内形成宏观形状锁定，以增强固定强度。这种新型脊柱骨锚固件的放置安全性和固定强度均在组织模型（Sawbones）上得到了验证。弯曲柔性锚固件路径的半径显示出高精度，同时对其放置的骨密度表现出强烈依赖性。当弯曲柔性锚固件与传统椎弓根螺钉结合使用时，平均最大拔出力提高到290 N，与单独使用椎弓根螺钉相比，拔出阻力提高了14%。用多个弯曲柔性锚固件进一步增强固定有望实现更大的固定效果。弯曲柔性脊柱骨锚固件的应用为提高椎弓根螺钉的固定强度提供了一种有前景的方法，这在具有挑战性的临床场景中尤为重要，比如患有骨质疏松症的患者。
