A Simulation Analysis About The Effects Of The Joint Line’s Height On Mechanical Characteristics Of Artificial Knee After TKA Of Human’s Knee

This research is supported by National Natural Science Foundation of China on research on high-flexion stability mechanism of high-flexion artificial knee to study the effects of the joint line’s height on mechanical characteristics of artificial knee after TKA.In order to determine a reasonable variation range of the joint line’s height to help clinical researches,this paper analyzed the effects of the joint line’s height on mechanical charateristics of artificial patellofemoral and tibiofemoral joints after total knee arthroplasty(TKA).In order to establish a fully three-dimensional geometric model of the knee joint.Secondly,CT and MR scanning images were used to obtained the relevant data of the knee.Simulating the TKA surgery and combining with the study data of literature defined material properties of each knee bones and soft tissues,the corresponding loads,and boundary conditions.A normal knee joint line as standard zero,11 groups of finite element models totally were established according to joint line’s height which changed 1mm every time from-4mm to + 6mm.Dynamic finite element simulation was used to analyze the biomechanical effects of the artificial patellofemoral and tibiofemoral joints in a weight-bearing state during squating exerciseThe contact stresses of tibiofemoral and patellofemoral joints were increased accordingly with the increase of the flexion angle during squating exercise.Reasonable variation interval of joint line’s height was-1mm ~ + 3mm and-1mm ~ + 5mm respectively for artificial patellofemoral and tibiofemoral joints.when the knee joint line’s height above this range,the local contact stress amplitudes of the patellofemoral and tibiofemoral joints fluctuated significantly which will lead to the wear of polyethylene prostheses increased.When the knee joint line’s height below this range,soft tissues’ constrains were insufficient and the risk of tibiofemoral joints’ dislocation increased.When a small artificial knee prosthesis model was selected,the clinical need to maintain that the variation interval of joint line’ height is-1mm ~ + 3mm after TKA,which can be helped to reduce the peaks of local stresses,prolonge the longevity of ultra-high molecular polyethylene prosthesis,preserve locking mechanism of soft tissues,and reduce the risk of tibiofemoral joint’ dislocation.