Bone Marrow Changes in Osteoporosis

Abstract

Bone research in osteoporosis has quite rightly focused on the mineralised component of bone as this is the component that is ultimately responsible for bone strength. However, the non-mineralised component of bone, i.e. the bone marrow, is many times more metabolically active and responsive than the mineralised component of bone. Despite this, the bone marrow has been relatively overlooked with regard to the pathogenesis of osteoporosis and related conditions. This has changed with magnetic resonance imaging and positron emission tomography allowing non-invasive quantification of bone marrow physiology and pathology on a large scale. Aspects of the bone marrow that can be evaluated on imaging are marrow fat content, perfusion, molecular diffusion and metabolic activity. There are many ways in which bone marrow metabolism may potentially influence bone metabolism. For example, the bone marrow forms the microenvironment of biologically relevant endosteal and trabecular bone and this bone may be responding to changes in the bone marrow. Similarly, the bone marrow contains pluripotent mesenchymal stem cells with the ability to differentiate preferentially along either haematopoetic, adipocytic or osteoblastic cell lines. Preliminary research has shown how bone loss in senile osteoporosis mass is accompanied by scalar changes in marrow fat content, marrow perfusion and marrow diffusion. Similar to the bone loss of osteoporosis, the bone marrow changes in osteoporosis represent an exaggeration of physiological age-related change. Bone marrow changes occur in synchrony rather than pre- or post-date changes in the mineralised component of bone. Whether the bone marrow is an active contributor or a passive bystander to physiological and osteoporotic bone loss remains to be seen.KeywordsBone Mineral DensityApparent Diffusion CoefficientFatty MarrowBone Marrow ChangeBone Blood FlowThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.