Efficacy of dynamic load during walking on the prediction of rebound effects following guiding growth intervention in children with angular deformities

理由：由于膝关节一侧承受了过多的负荷，膝关节的不对准容易导致单室变性。因此，在骨骼未成熟的患者中推荐引导生长。然而，种植体移除后经常会出现反弹效应（不对准的复发）。到目前为止，造成这种现象的原因还没有得到很好的理解，也不存在硬件移除的最佳时间标准。这个时间对轴向校正的长期成功至关重要。此外，硬件移除的指示是基于站立时的静态测量，不能反映实际负载情况和行走时的个体补偿机制。目的：本研究的目的是探讨行走时动态负荷对张力带板引导生长干预后反弹效应的影响。方法：在张力带钢板植入和取出前一天采集步态分析和站立x线片。为了分析反弹效应，将在移植后6个月和12个月进行无创步态分析。为了评估每日累积负荷，将使用移动步数追踪器。为了预测膝关节负荷状态作为动作肌肉的函数，将应用多体模拟，并与步态分析的膝关节负荷测量进行比较。人群：142例特发性腿内翻或外翻畸形患儿和60例典型发育年龄匹配对照。时间框架：预计持续时间为3年。在前六个季度，将招募患者和对照组。引导生长轴向矫正的预期时间平均为12个月，拔除后随访时间分别为6个月和12个月。预期结果：根据目前仅基于静态测量的硬件移除算法，少数患者可能在移除后出现病理性膝关节负荷。由于载荷情况影响骨重塑，病理性载荷可能与较高的反弹效应有关。这项研究的结果将首次深入了解骨骼和肌肉在指导生长期间和之后的机械完整性。这可能会改进治疗算法。

Rationale: Malalignment of knee joints is predisposed to the development of unicompartmental degenerations because of the excessive load placed on one side of the knee. Therefore, guided growth in skeletally immature patients is recommended. However, a rebound effect (recurrence of the malalignment) after implant removal frequently occurs. Up to now, the reasons for this phenomenon are not well understood and standards for optimal timing for hardware removal do not exist. This timing is crucial for the long term success of the axial corrections. In addition, indication for hardware removal is based on static measures during standing that does not reflect the actual load situation and individual compensatory mechanisms during walking. Objectives: The aim of the study is to investigate the influence of the dynamic load during walking on the rebound effect following a guiding growth intervention using tension band plates. Methods: Gait analysis and standing radiographs will be captured the day before implantation and explantation of tension band plates. To analyse rebound effects, non-invasive gait analysis will be performed 6 and 12 months after explantation. To assess daily cumulative loadings mobile step trackers will be used. In order to predict the knee joint loading regime as a function of acting muscles, multi-body simulations will be applied and additionally compared with knee joint loading measures of gait analyses. Populations: 142 children with idiopathic varus or valgus leg malalignment and 60 typically developed age matched controls. Timeframe: The anticipated duration is 3 years. During the first six quarters patients and controls will be recruited. The expected time of axial correction through guiding growth is on average 12 month, the follow up time after removal is 6 and 12 months. Expected outcome: According to the current algorithm for hardware removal, which is based only on static measurements, a few patients may show a pathologic knee joint loading after explantation. Since the load situation affects bone remodelling, pathological loads may be related to higher rebound effects. The results of this study should give first time insights into the mechanical integrity of bones and muscles during and after guiding growth. This may improve the treatment algorithm.