Spongiösen

Spongiösen, or spongy bone tissue, is the porous interior of bones and is also referred to as cancellous bone. It forms a lattice of trabeculae—the thin, rod- and plate-like elements—that create a sponge-like framework with interconnected spaces.

The trabecular network is most prominent in the epiphyses of long bones, inside the vertebral bodies, the pelvis, ribs, and the interior of flat bones. Its spaces are typically filled with red bone marrow in children and with varying amounts of red and yellow marrow in adults. The arrangement of trabeculae follows the lines of mechanical stress, providing structural support while keeping the bone lightweight and capable of metabolic exchange.

Functionally, spongiösen serves multiple roles. The porous architecture distributes loads efficiently, contributing to the mechanical strength of bones. The large surface area facilitates hematopoiesis in red marrow and mineral homeostasis through exchange of calcium, phosphate, and other ions between bone and blood.

Remodeling of spongiösen involves the coordinated activity of osteoblasts and osteoclasts, a continual process that adapts the trabecular structure to changing mechanical demands and metabolic needs. Because trabecular bone has a high turnover rate, it is particularly susceptible to conditions that reduce bone density.

Clinically, loss of trabecular bone mass is a hallmark of osteoporosis and contributes to fracture risk, especially in the spine, hip, and wrist. Imaging and biopsy often reveal thinning and disorganization of the trabecular network, underscoring the importance of spongiösen in skeletal health.