アルミナ・セラミックス人工足関節置換後における足関節の2次元FEMによる解析

Abstract

Normally, arthrodesis is indicated if only an ankle joint is destroyed. However if there are pathological changes in the neighboring joints, it is desirable to preserve joint functions and an artificial ankle joint replacement is indicated in many cases. We made models of the lateral views of ankle joints and performed a comparative investigation of (1) deformations and (2) major and minor principal stresses by means of the finite element method by inferring (1) physiological conditions, (2) conditions immediately after replacement with an artificial ceramic joint, which we developed, without cement, (3) conditions of fusion between the ceramic and the bone a few months after the replacement, and positions of a lower leg (4) standing on one leg medially, (5) inclined posteriorly and (6) inclined anteriorly. The NASTRAN program was used in the analysis and membrane and rod elements were used for element divisions. A tibial component of an artificial joint was loaded mainly on the anterior cortical bone of the tibia and on the posterior cancellous and cortical bone. A component of a talus having a stem in the center replaced a joint surface. The physiological stress distribution was similar to the travecular course. Immediately after replacement with an artificial joint, there was a large amount of stress in the ceramic, but compressive stress was found between the ceramic and the bone. After fusion between the artificial joint and the bone, stress distributions changed to approximately the same conditions as the physiological conditions. These results were investigated comparatively with clinical results.