Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.
Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.
Spine J. 2021 May;21(5):842-854. doi: 10.1016/j.spinee.2021.01.011. Epub 2021 Jan 19.
Correction of adult spinal deformity (ASD) by long segment instrumented spinal fusion is an increasingly common surgical intervention. However, it is associated with high rates of complications and revision surgery, especially in the elderly patient population. The high construct stiffness of instrumented thoracolumbar spinal fusion has been postulated to lead to a higher incidence of proximal junctional kyphosis (PJK) and failure (PJF). Several cadaveric biomechanical studies have reported on surgical techniques to reduce the incidence of PJF/PJK. As yet, no overview has been made of these biomechanical studies.
To summarize the evidence of all biomechanical studies that have assessed techniques to reduce PJK/PJF following long segment instrumented spinal fusion in the ASD patient population.
A systematic review.
EMBASE and MEDLINE databases were searched for human and animal cadaveric biomechanical studies investigating the effect of various surgical techniques to reduce PJK/PJF following long segment instrumented thoracolumbar spinal fusion in the adult patient population. Studied techniques, biomechanical test methods, range of motion (ROM), intervertebral disc pressure (IDP) and other relevant outcome parameters were documented.
Twelve studies met the inclusion criteria. Four of these studies included non-human cadaveric material. One study investigated the prophylactic application of cement augmentation (vertebroplasty), whereas the remaining studies investigated semi-rigid junctional fixation techniques to achieve a gradual transition zone of forces at the proximal end of a fusion construct, so-called topping-off. An increased gradual transition zone in terms of ROM compared to pedicle screw constructs was demonstrated for sublaminar tethers, sublaminar tape, pretensioned suture loops, transverse hooks and laminar hooks. Furthermore, reduced IDP was found after the application of sublaminar tethers, suture loops, sublaminar tapes and laminar hooks. Finally, two-level prophylactic vertebroplasty resulted in a lower incidence of vertebral compression fractures in a flexion-compression experiment.
A variety of techniques, involving either posterior semi-rigid junctional fixation or the reinforcement of vertebral bodies, has been biomechanically assessed. However, the low number of studies and variation in study protocols hampers direct comparison of different techniques. Furthermore, determination of what constitutes an optimal gradual transition zone and its translation to clinical practice, would aid comparison and further development of different semi-rigid junctional fixation techniques. Even though biomechanics are extremely important in the development of PJK/PJF, patient-specific factors should always be taken into account on a case-by-case basis when considering to apply a semi-rigid junctional fixation technique.
通过长节段器械固定脊柱融合术矫正成人脊柱畸形（ASD）是一种越来越常见的手术干预措施。然而，它与高并发症发生率和翻修手术率相关，尤其是在老年患者群体中。器械固定胸腰椎脊柱融合的高结构刚度被认为会导致更高的近端交界性后凸（PJK）和失败（PJF）发生率。几项尸体生物力学研究已经报道了降低 PJF/PJK 发生率的手术技术。然而，目前还没有对这些生物力学研究进行综述。
总结所有评估 ASD 患者人群中行长节段器械固定脊柱融合术后降低 PJK/PJF 发生率的技术的生物力学研究的证据。
系统综述。
在 EMBASE 和 MEDLINE 数据库中搜索了评估各种手术技术以降低成人患者人群中行长节段器械固定胸腰椎脊柱融合术后 PJK/PJF 发生率的人类和动物尸体生物力学研究。记录了研究技术、生物力学测试方法、活动度（ROM）、椎间盘压力（IDP）和其他相关结果参数。
符合纳入标准的研究有 12 项。其中 4 项研究包括非人类尸体材料。一项研究调查了预防性应用骨水泥增强（椎体成形术）的效果，而其余研究则调查了半刚性交界固定技术，以实现融合结构近端力的逐渐过渡区，即所谓的“ topping-off”。与椎弓根螺钉结构相比，板层内固定、板层带、预紧缝线环、横钩和板层钩的 ROM 逐渐过渡区更大。此外，板层内固定、缝线环、板层带和板层钩的应用可降低 IDP。最后，在屈伸压缩实验中，两水平预防性椎体成形术可降低椎体压缩骨折的发生率。
已经对涉及后外侧半刚性交界固定或增强椎体的多种技术进行了生物力学评估。然而，由于研究数量少且研究方案存在差异，限制了不同技术的直接比较。此外，确定什么构成最佳的逐渐过渡区及其向临床实践的转化，将有助于不同半刚性交界固定技术的比较和进一步发展。尽管生物力学在 PJK/PJF 的发展中非常重要，但在考虑应用半刚性交界固定技术时，应始终根据具体情况考虑患者的具体因素。
