Design And Evaluation Of An Overall Unloading Knee Brace

Knee is the most important weight-bearing joint of the body. It is thehub of the lower extremity which has complex structure and bearslong-term and a large amount of load. Therefore, the injury rate of it is alsoamong the first of all the joints. Among these diseases, one of the mostcommon symptoms is osteoarthritis (OA), and long-term and a largeamount of load is the leading reason for OA and joint pain. Meanwhile, theknee cartilage wear and tear and meniscus injury are also commondisorders of the knee which are related with joint load. Using knee bracesbecome an important means to treat these diseases, reduce pain and restorethe ability to walk by correcting joint lines and redistributing joint load.The thesis first introduced orthoses classification, function, materials,biomechanics, design principles, development trends, users’ psychology,and possible side effects.Secondly, taking “unloading” as core, the thesis analyzed the role andmechanism of joint load in OA, the knee cartilage wear and tear andmeniscus injury on the basis of describing the anatomical structures of theknee joint, movement characteristics, lower limb bearing mechanism.According to the analyses, treatment programs were elaborated such asweight loss, strengthening the exercise training of the lower extremity,changing the movement pattern and application of orthopedic or boosterequipment.Again, the thesis proposed a novel way to unload the two condyles ofthe knee through analyzing the mechanism and limitations of the existingunloading knee brace in the market. That is to pass the part of load abovethe knee to the below part directly by mechanism, so it is the knee and device to take the load together. Then, according to this idea, six differentkind of mechanisms were designed which all can convent the rotationalmovement of the knee to the liner movement of the thing holder makingunloading possible. At the same time, the six mechanisms were carried outmovement and mechanical analysis, comparing the advantages anddisadvantages of them and then I chose the best solution for overall designand optimization of the orthosis structure.Finally, in order to verify the role of unloading and consider safetyfactors, the thesis analyzed the role of the final device to the knee in detailincluding the restriction and protection of the device to the joint force line;thigh prop under the force of the thigh holder; the influence of the differentlocation between the knee instantaneous center and the institutional centerof rotation to the lower limb flexion and extension. And through theestablishment of a biomechanical model of the lower limb and the device,knee contact force relief was proved by force analysis of the kneeextension under the action of the device. But the result reveals thecontradiction between unloading capacity and quadriceps load. Then itseffect to people was evaluated generally by the biomechanical experimentwhich builds the relationships between pressures, shears force and skindeformation range of thign and the damping characteristics, resistancemoment and extra energy to use the device are also obtained. After allthese efforts, the thesis proved the effectiveness of the mechanism andevaluated the new brace safety and effect to body preliminarily.