Design, development and validation of adjustable knee brace using experimental and computational methods

膝关节支架通常用于在前交叉韧带（ACL）重建手术后稳定膝关节。目前不存在允许在康复期间逐渐加载膝盖结构从而使得组织能够适当愈合的膝盖支具。我们建议使用体内/体外联合方法来验证用于测试膝关节支架设计的人体膝关节的详细有限元模型。然后将使用经过验证的有限元模型设计能够逐渐加载/卸载膝盖结构的新膝盖支架。 将对进行正常活动（如行走和下蹲）的男性活体受试者进行运动捕捉。运动捕捉数据将被输入到刚体生物力学模型中，以计算这些活动期间下肢的肌肉力量分布。将获得10个新鲜冷冻尸体膝关节。膝盖将被切开，肌肉将被与僵硬肌肉的弹性模量相匹配的泡沫代替。然后，动态膝关节模拟器系统将生理肌肉力和膝关节运动学（如通过生物力学模型计算的）施加在尸体膝关节上，具有和不具有支架。将使用植入式传感器测量ACL应变。 然后将提取膝关节韧带和踝关节组织并进行拉伸试验，以获得这些组织的机械性能。将组织的材料特性分配给膝关节的高级FE模型，该模型将承受与动态膝关节模拟器中相同的载荷。将得到的ACL和ACL应变与实验结果进行比较，以验证模型。 然后将开发新的膝关节支架设计。支撑将允许ACL加载的自定义。将使用经验证的FE模型优化新设计。将推导出新型可调节膝关节支具的各种配置与产生的ACL应变之间的关系。新的设计可以减少ACL重建失败，从而降低相关的医疗费用。

Knee braces are often used to stabilize the knee joint following anterior cruciate ligament (ACL) reconstructive surgery. There currently exists no knee brace that allows gradual loading of the knee structures over the rehabilitation period thereby enabling proper healing of the tissue. We propose to use a combined in-vivo/in-vitro methodology to validate a detailed finite element model of human knee for testing knee brace designs. The validate finite element model would then be used design a new knee brace with the capability to progressively load/unload knee structures. Motion capture will be performed on live male subject performing normal activities such as walking and squatting. The motion capture data will be input into a rigid body biomechanical model to calculate muscle force profiles in the lower extremity during those activities. Ten fresh frozen cadaver knees will be obtained. The knees will be dissected the muscles will be substituted by foam that matches the modulus of elasticity of the stiff muscles. A dynamic knee simulator system then applies physiological muscle forces and knee kinematics (as calculated through the biomechanical model) on the cadaver knees, with and without braces. ACL strain will be measured using implanted transducers. The knee ligament and meniscal tissues will then be extracted and tested in tension to obtain the mechanical properties of these tissues. The material properties of the tissues will be assigned to an advanced FE model of the knee which will be subjected to same loading as subjected to in the dynamic knee simulator. The resulting ACL and meniscal strains will be compared with experimental results to validate the model. A new knee brace design will then be developed. The brace would enable the customization of ACL loading. The new design will be optimized using the validated FE model. Relationship between various configurations of the new adjustable knee brace and resulting ACL strain will be derived. The new design could result in lesser failed ACL reconstruction thereby decreasing the associated healthcare costs.