Cancellous, trabecular or spongy bone is one of the two macroscopic forms of bone, the other being cortical bone, and comprises 20% of skeletal mass.
Cancellous bone is located in the medullary cavity of bone, in particular tubular and short bones, and consists of dense trabeculae (struts) that traverse the bone marrow-filled medullary cavity . Trabeculae are geometrically arranged to resist local forces transmitted through the bone and are adaptable. Microscopically it is the same as cortical bone.
The function of cancellous bone is to provide strength and support to the overlying bony cortex whilst minimizing weight.
Trabeculae are visible in the medullary cavities of bone as dense struts of bone that parallel the lines of force that the particular bone is subject to.
Cancellous bone appears radiopaque (white) on computed tomography, with trebeculae the same density as cortical bone, whereas the marrow is of intermediate density.
The signal intensity of trabeculae follows that of cortical bone, being low on T1 and T2 weighted images. The marrow which the trabeculae traverse, however, may be of different signal intensities, depending on the proportion of red and yellow marrow, or the presence of a marrow disease process.