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

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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.