勾画磁控生长棒：对扩张能力和近段交界性后凸的影响。
Contouring the magnetically controlled growing rods: impact on expansion capacity and proximal junctional kyphosis.
机构信息
Department of Orthopedic Surgery, University of Pennsylvania, Philadelphia, PA, USA.
Division of Orthopedic Surgery, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
出版信息
Eur J Orthop Surg Traumatol. 2021 Jan;31(1):79-84. doi: 10.1007/s00590-020-02743-x. Epub 2020 Jul 26.
OBJECTIVE
To quantitatively determine the relationship between the contouring of the magnetically controlled growing rods (MCGR), their expansion capacity and the risk of developing proximal junctional kyphosis in early onset scoliosis (EOS). MCGRs allow gradual expansion and correction of the spinal deformity in EOS while reducing the need for repeated surgeries. As the expansion of the MCGRs is controlled externally, several factors can impact the discrepancy between the intended and actual expansions of the rods. The expansion capacity of the growing rods as a function of the expanded length has been tested in experimental setups; however, no study has evaluated the role of contouring of the MCGRs on its function and long-term surgical outcome.
METHODS
A total of 25 EOS patients, a total of 48 MCGRs, with right thoracic curves, were studied retrospectively. All patients had two view spinal radiographs at pre-operative, after MCGR implantation, and after 6 lengthening visits. The first post-operative radiographs were used to calculate the 3D contour of the MCGR at the proximal end. 2D ultrasound images before and after lengthening visits were used to measure the rod lengthening at each visit. The relationship between the increase in the rod length and rod curvature was determined. Finally, the rod curvature was correlated to the changes in proximal junctional kyphosis (PJK) angle between the pre-operative and the most recent follow-up, i.e., after 6 visits.
RESULTS
The average rod 3D angle at the proximal end was 13.5° ± 9.7° [0°-37.2°]. The overall increased length after six lengthening visits for the rod at the concave side was 18.8 mm and at the convex side was 16.9 mm. 62% of the patients with a contoured rod at the proximal end developed a PJK exceeding 10° whereas in patients with a straight rod PJK occurred in 9.1%.
CONCLUSIONS
Contouring the MCGR impacts both the mechanics of the rod expansion and the prevalence of PJK in EOS patient population.
目的
定量研究磁控生长棒（MCGR）的轮廓、扩张能力与早发性脊柱侧凸（EOS）中近端交界性后凸（PJK）风险之间的关系。MCGR 允许在减少多次手术的同时，逐渐扩张和矫正 EOS 中的脊柱畸形。由于 MCGR 的扩张是外部控制的，因此有几个因素会影响棒的实际扩张与预期扩张之间的差异。已经在实验装置中测试了生长棒的扩张能力作为扩展长度的函数；然而，尚无研究评估 MCGR 的轮廓对其功能和长期手术结果的影响。
方法
回顾性分析 25 例右侧胸弯 EOS 患者，共 48 根 MCGR。所有患者在术前、MCGR 植入后和 6 次延长就诊时均拍摄双视图脊柱 X 线片。第一次术后 X 线片用于计算 MCGR 近端的 3D 轮廓。在延长就诊前后使用 2D 超声图像测量每次就诊时的棒延长长度。确定杆长度增加与杆曲率之间的关系。最后，将杆曲率与术前和最近随访时（即 6 次就诊后）近端交界区后凸（PJK）角度的变化相关联。
结果
近端 MCGR 的平均杆 3D 角度为 13.5°±9.7°[0°-37.2°]。在 6 次延长就诊后，凹侧杆的总延长长度为 18.8mm，凸侧为 16.9mm。近端有轮廓的 MCGR 患者中，62%发生 PJK 超过 10°，而直杆患者中 PJK 发生率为 9.1%。
结论
MCGR 的轮廓会影响棒的扩张力学和 EOS 患者人群中 PJK 的发生率。
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