Bone Abstracts

Introduction: Hereditary multiple osteochondromas (HMO) is characterized by the outward growth of cartilage-capped bone tumors. Osteochondromas contain a bone marrow cavity continuous with the normal bone cavity. Because of their off-axis position, osteochondromas are expected to carry less load than normal bone tissue. According to Wolff’s law, we therefore hypothesized that osteochondromas would have a less developed, osteoporotic-like microstructure. To test this hypothesis, we measured the bone morphology of osteochondromas with microCT scanning and compared it to normal bone. To our knowledge this is the first study done with microCT and human osteochondromas.

Materials and methods: Micro-CT scans were made of thirteen osteochondromas from human subjects to evaluate tissue mineralization and bone structural parameters. Values for normal bone were taken from the literature.

Results: Large differences in tissue mineralization were found, with three specimens being hardly mineralized and the others being less mineralized than normal bone. The osteochondromas have less but thicker trabeculae than normal bone. The spacing between the trabeculae is increased. The structure lacks a clear orientation, being more isotropic than normal bone.

Discussion: Osteochondromas resemble an osteoporotic structure in some aspects (increased trabecular spacing, decreased trabecular number) but the osteochondromas have a higher trabecular thickness. This may be due to the influence of the cartilage cap nearby. The osteochondromas also lack a clear trabecular orientation, probably due to the absence of mechanical loading.

Conclusion: Osteochondromas have a less developed structure, as witnessed by the lower mineralization and the absence of a clear trabecular orientation, but is not comparable to osteoporotic bone.

Significance: This study is the first to show that the architecture of the osteochondromas is not osteoporotic. It only resembles an osteoporotic structure in some aspects (increased trabecular spacing, decreased trabecular number) but that they have a higher trabecular thickness.