2014 年 9 巻 2 号 p. 13-00164
Articular cartilage is a cushioning material which reduces contact pressure on joint, and protects subchondral bone from direct load. In the recent studies on mechanical behavior of cartilage, detailed cartilage geometries were available by means of in vivo CT and/or MR imaging. The mechanical property on the cross-section of cartilage is inhomogeneous due to its laminar microstructure. However, the studies are limited for detailed stress distribution in cartilage taking the effect of internal microstructure of cartilage even when those have taken the real bone/cartilage shape into account for finite element analysis (FEA). In this study, the FEA of cartilage layer of hip joint extracted from the 3D-CT image was performed in order to obtain knowledge of the stress distribution in detail considering the inhomogeneity of articular cartilage. The real bone surface geometries of femoral heads and acetabular fossae were extracted from 3D-CT image. The geometry of cartilage is defined by referring to the bone surface so that the femoral joint surfaces are reproduced. This study modeled the bilateral hip joints of healthy subjects. The reproduced femurs were discretized into 8-node brick elements for bone and cartilage layers of the hip joint. The mechanical properties used for FEA were those estimated by considering the microstructure in the previous study. High stress was observed mainly on cartilage surface covered with the acetabular fossa. Especially stress concentration was located at proximal surface of femoral head, while the stress at the lower distal region was not significant.
