Microarchitecture and Bone Strength
Bone mass measured by BMD explains about 60% to 85% of the variation in bone strength,¹⁷and models of fracture risk have focused predominantly on losses of bone mass. However, the underlying microarchitecture of bone, in addition to bone mass, also affects bone strength. Bone mechanical strength is related to the shape, width and connectivity of the cancellous bone. Bone loss that causes discontinuity within the trabeculae irreversibly weakens the structural integrity of the bone, a more serious consequence than mere thinning of the trabeculae. This is referred to as "loss of connectivity." Once the trabeculae are disrupted, deposition of new bone matrix may merely thicken the remaining trabeculae, rather than restoring continuity, so the bone may never be able to return to normal strength.