Musculoskeletal modeling and simulations of scoliotic standing postures

青少年特发性脊柱侧凸（AIS）不仅以脊柱变形和胸腔扭曲为特征，而且还表现为头、肩和骨盆在所有三个平面上的方向改变。脊柱的畸形、形态和姿态反映在体节惯性参数（BSIP）中。虽然有文献证据表明BSIP影响站立姿势和平衡，但对其与肌肉控制的相互作用知之甚少。总体研究目标是建立以脊柱侧凸躯干为重点的肌肉骨骼模型，模拟BSIP在不同直立姿势条件下的影响，并估计AIS女孩恢复平衡所需的肌肉激活。具体目标是在SIMM/Opensim的肌肉骨骼模型中开发一个通用的健全（AB）和三个通用的脊柱模块，用于小、中、重度畸形；模拟10名健全女生和30名AIS女生在8种直立姿势条件下站立平衡的BSIP和肌肉力矩的变化，并使用受试者特异性模型模拟躯干肌肉激活模式以改善AIS的站立平衡。为了进行这些模拟，个性化的3D脊柱数据将由EOS系统获得，这是一种超低剂量数字x射线辐射技术，可用于临床和体内个性化BSIP，使用的方法是我之前的发现基金中开发的。站立平衡将通过两个测力板和一个基于6个摄像头的视频系统来量化。然后将在SIMM中开发的脊柱模块导入OpenSim进行模拟。这些软件目前在实验室中可用。如果调整肌肉力矩可以改善AIS中的站立平衡，那么这些模拟将测试哪些肌肉最有效。虽然我们在我们的肩部模型中使用了类似的方法，其他人在运动过程中建模下肢，但没有人解决脊柱侧凸中的站立平衡，不对称站立姿势和肌肉模拟。本研究为脊柱侧凸肌肉骨骼模型工具包奠定了基础，并提供了具有潜在临床影响的独特和新颖的进展，从而导致更好的姿势训练计划，改进身体支架和脊柱内固定。

Adolescent idiopathic scoliosis (AIS) is not only characterized by a deformed spine and rib cage distortion but also by altered head, shoulders and pelvis orientation in all three planes. Spinal deformity, morphology and posture are reflected in the body segment inertial parameters (BSIP). Though there is literature-based evidence that BSIP affects standing posture and balance little is known about their interaction with muscle control. The overall research goal is to develop musculoskeletal models focusing on the scoliotic trunk to simulate the effects BSIP in different upright stance conditions and estimate muscle activations required to restore balance in AIS girls. The specific objectives are to develop a generic able-bodied (AB) and three generic spine modules for small, moderate and severe deformity in the musculoskeletal models of SIMM/Opensim; simulate changes in BSIP and muscle moments on standing balance in 10 able-bodied and 30 AIS girls for eight upright stance conditions and simulate trunk muscles activation patterns using subject-specific models to improve standing balance in AIS. To perform these simulations personalized 3D spine data will be obtained by the EOS system, an ultra low dose digital X-ray radiation technique, available at the clinic and in-vivo personalized BSIP using methods developed in my previous Discovery grant. Standing balance will be quantified by two force plate and posture by a 6 camera video-based system. The spine modules to be developed in SIMM will then be imported into OpenSim for the simulations. These softwares are currently available in the laboratory. If modifying muscle moment can improve standing balance in AIS then these simulations will test which muscles are the most effective. Though we are using similar approaches in our shoulder model and others in modeling the lower limbs during locomotion no one addressed standing balance, asymmetrical standing postures and muscle simulations in scoliosis. This research develops the foundations for a scoliotic spine musculoskeletal model toolkit and provides a unique and novel advance with potential clinical impact leading to better posture training programs and improve body brace and spinal instrumentation.