Clin Julien, Le Navéaux Franck, Driscoll Mark, Mac-Thiong Jean-Marc, Labelle Hubert, Parent Stefan, Shah Suken A, Lonner Baron S, Newton Peter O, Serhan Hassan
Spinologics, Inc., 6750 Avenue de l'Esplanade #290, Montréal, Quebec, H2V 1A2, Canada.
Spinologics, Inc., 6750 Avenue de l'Esplanade #290, Montréal, Quebec, H2V 1A2, Canada.
Spine Deform. 2019 Jan;7(1):2-10. doi: 10.1016/j.jspd.2018.06.007.
Biomechanical numerical simulation analysis of implant design and density in adolescent idiopathic scoliosis posterior instrumentation.
To evaluate the combined effect of pedicle screw design and density on deformity correction and construct load-sharing capacity.
Screw density is an area of popular study because of the impact of cost and potential patient morbidity of higher-density constructs. Using fewer screws raises concern about reduced correction and greater forces on each screw.
Personalized spinal numerical models were created for five patients. The correction techniques from five spine surgeons using both a high- and a low-density implant pattern (2 vs. 1.4 ± 0.22 screws/level) with uniaxial, multiaxial, and favored angle screws were simulated. The predicted correction and forces sustained by the implants were compared. The postoperative load-sharing capacity of a high- and a low-density construct, with or without crosslinks, was compared by simulating daily activities motions.
The major coronal curve correction was similar with high- and low-density constructs (73% ± 10% vs. 72% ± 10%; p > .05) but was higher when using uniaxial (77% ± 8%) compared to multiaxial (69% ± 11%) and favored angle screws (71% ± 10%; p = .009). High- and low-density constructs sustained similar intraoperative peak forces (305 ± 61 N vs. 301 ± 73 N; p = .23) regardless of screw design (all p > .05). Multiaxial and favored angle screws reduced the peak axial force by 23% and 38% compared to uniaxial screws (p = .007). The high-density construct reduced the postoperative loads sustained by each implant by 31% (p = .006). Crosslinks had no effect on load sharing (p = .23).
High- and low-density implant patterns achieved similar coronal correction with equivalent capacity to share corrective forces regardless of the screw design. Increased degrees of freedom of the screw head reduces the capacity to correct coronal deformity but generates lower bone-screw forces. The reduced number of screws increased the postoperative forces sustained by each screw, but its effect on potential complications requires further investigations.
Level 4.
青少年特发性脊柱侧弯后路内固定中植入物设计与密度的生物力学数值模拟分析。
评估椎弓根螺钉设计和密度对畸形矫正及内固定分担负荷能力的联合影响。
由于高密度内固定物的成本影响及潜在的患者发病率，螺钉密度是一个热门研究领域。使用较少螺钉引发了对矫正效果降低及每个螺钉受力增大的担忧。
为5名患者创建个性化脊柱数值模型。模拟了5位脊柱外科医生分别使用高密度和低密度植入模式（2枚/节段对比1.4±0.22枚/节段），以及单轴、多轴和偏角螺钉的矫正技术。比较了预测的矫正效果及植入物承受的力。通过模拟日常活动动作，比较了有或无横向连接的高密度和低密度内固定物术后的负荷分担能力。
高密度和低密度内固定物的主要冠状面曲线矫正效果相似（73%±10%对比72%±10%；p>.05），但与多轴螺钉（69%±11%）和偏角螺钉（71%±10%）相比，使用单轴螺钉时矫正效果更高（77%±8%；p=.009）。无论螺钉设计如何，高密度和低密度内固定物承受的术中峰值力相似（305±61N对比301±73N；p=.23）（所有p>.05）。与单轴螺钉相比（p=.007），多轴和偏角螺钉使峰值轴向力分别降低了23%和38%。高密度内固定物使每个植入物术后承受的负荷降低了31%（p=.006）。横向连接对负荷分担无影响（p=.23）。
无论螺钉设计如何，高密度和低密度植入模式在冠状面矫正效果及分担矫正力的能力方面相似。螺钉头部自由度增加会降低冠状面畸形矫正能力，但会产生较低的骨 - 螺钉力。螺钉数量减少会增加每个螺钉术后承受的力，但其对潜在并发症的影响需要进一步研究。
4级。
