Numerical analysis evaluation of artificial joints.

Artificial joints are exposed to loads on a daily basis. Loads on the bone through the artificial joint and the joint's sliding surface shear force may cause implant fixation failure, fatigue fractures, wear of the bearing and foreign body reactions. Artificial joints can experience sudden internal damage, which can be fatal if it occurs during activities performed at high altitudes or in water. The standard design hip prosthesis has a metal femoral stem. Most stem fractures are caused at the proximal one third of the stem by fatigue due to repetitive loading. Femoral stem neck fractures can also occur. To eliminate in vivo prosthesis failures, safety performance preclinical studies evaluate stem body and neck breakage. However, the development of new femoral stems via prototyping and fatigue test verification would require excessive time and money. Therefore, evaluation methods based on numerical analyses, such as finite element analysis (FEA), have been introduced to simulate tests on actual machines. Fatigue strength design verification using FEA can efficiently identify a design that can pass International Organization for Standardization fatigue tests. FEA may also aid with composite implant development by enabling efficient preclinical testing to prove safety using minimal actual fatigue testing. Once a biological safety study of a composite material is performed, a clinical trial can prove its clinical efficacy and safety and device regulatory approval can be requested. This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2020 (Vol. 49, No. 3, pp. 195-198), with adding some additional contents and references.