[Distribution of trabecular microfractures in the proximal femur--with the epiphyseal scar as a landmark].

The distribution of the trabecular microfractures in normal human proximal femora was investigated to see whether they were related to the femoral neck fracture of the elderly. In this study the epiphyseal scar was employed as an anatomical landmark in the proximal femur, since the authors' observation suggested that it remained throughout life and was located in constant connection with the margin of the articular cartilage. The medial aspect of the proximal femur was divided into three anatomical zones, which were called epiphyseal, subepiphyseal and subcapital ones, respectively. There were two areas in which trabecular microfractures concentrated; one was about the lateral end of the epiphyseal scar and another the subepiphyseal zone. Few microfractures were noted on the principal compressive trabeculae. A femoral neck fracture of the elderly usually provides a fracture line running from the lateral end of the epiphyseal scar down to the subcapital zone. Thus the fracture takes place just within the area of concentration of trabecular microfractures laterally, whereas it passes caudad to the medial group of microfractures. The authors hypothesize that the trabecular microfractures arising about the lateral end of the epiphyseal scar may have an etiological significance for the femoral neck fracture, in contrast that those in the subepiphyseal zone may not.