Design And Performance Evaluation Of An Overall Unloading Knee Brace

As the most complex and largest weight-bearing joint of human body, knee’s injury rate is the highest in all joints. The incidence rate of knee osteoarthritis is very high in the elderly. Overloading is one of the main factors that cause or accelerate the knee osteoarthritic. Hence, load reduction is an important treatment method of knee osteoarthritis. As a kind of external assistive device, unloading braces are widely used to reduce the load in the knee in the rehabilitation process.This thesis first introduced the anatomical structure of the knee and its motion, as well as the pathological features and the etiology of knee osteoarthritis. Then the biological influence of knee pressure on knee osteoarthritis is analyzed. By describing the research results of three different methods of unloading the force in the knee, the thesis confirms the importance of load reduction in the treatment of knee osteoarthritisSecondly, based on the mechanics in the knee, the mechanical model of the knee was built, the mechanism of wedge shoes and ‘three point’ orthotics was introduced. Qualitative analyses about the changes of the knee force when wearing wedge shoes or ’three point’ orthotics were conducted. The results showed that the force on the breaking side reduced while the other side overloaded. Hence, the concept of overall unloading brace was proposed. The working principle and mechanical design of the brace were introduced.Thirdly, based on the mechanical design and mechanical model proposed before, the biomechanical experiment was conducted and the feasibility of the unloading function of the brace was proved. In addition, the thesis analyzed the impact of the installation location and the pressure between the brace’s metal bracket and the thigh on the unloading forces. Experiment results indicated that the unloading forces would be large if the brace installed in the front side above the femoral condyle, and the unloading forces would grow up if the pressure between the strap and the thigh increase. The results also showed when the pressure was too large, the knee motion blocked.Finally, from the perspective of kinematic motions, the thesis described the changes of temporal and spatial parameters, such as gait stride, step length, walking speed and the changes of the knee s’ kinematic motions, as flexion angle, internal-external rotation angle and adduction-abduction angle by conducting gait experiments. The results proved that little changes of temporal and spatial parameters appeared after wearing the overall unloading brace and the brace didn’t affect the knees’ flexion and extension motion. These experiments preliminary evaluate the effectiveness of the brace.