The structure of the femoral neck: A physical dissection with emphasis on the internal trabecular system

Abstract

In an attempt to determine the position and course of the horizontal trabecular column within the femoral neck a series of femoral necks were dissected using a physical method. Unexpectedly, the findings of the study show that the internal structure of the femoral neck, overall, is more complex than has been previously described. Both trabecular columns blend intimately with the overlying cortex in the manner of a composite structure, which may have implications as to their strength. It was noted, as previously described in the literature, that the horizontal column has a spiral configuration. In addition it was found, in this study, that this column shows wide variation in its inclination between different specimens. With increasing osteoporosis, the remnant of the horizontal column comes to lie progressively more antero-superiorly within the femoral neck. While fairly uniform in cross-sectional area throughout the femoral neck, this column is found to arise from a large, internal buttress within the upper anterior femoral shaft. It is also found that the femoral calcar, initially, has widespread attachments to all the internal structures. It is accepted that the formation of these trabeculae, and their retention with age, is due to the forces acting through them. The findings of the study, however, suggest that the horizontal trabeculae are responsible primarily for the conduction of compression forces, rather than tension forces as described in the Trajectorial Theory. A suggestion as to how the compression forces may be conducted through both these columns in the upper femur is given in light of the findings. These concepts, if proven, may require a modification of the approach to the biomechanical analysis of this region, particularly when using the various imaging techniques, as well as with physical testing of prostheses and other such hip devices.