What are the causes of osteochondroma?

Etiology

Osteochondromas form from areas of retained cartilaginous growth at the end of a long bone. Cartilage formation overgrows the periosteum to produce an exostosis.

Causes of osteochondromas include:

- Genetic predisposition: Majority of osteochondromas are sporadic. However, heredity plays a role in 20% of the cases. If an individual inherits certain forms of osteochondroma then there are high chances that they may pass it to the next generation, especially in children.

- Familial osteochondromatosis: This condition is caused by a gene alteration in the EXT-1 or EXT-2 genes (exostosin-1 and exostosin-2 genes) that affects the body’s ability to develop cartilage. Due to this, there are multiple exostoses (overgrowths) that occur around multiple bones. People with familial osteochondromatosis or hereditary multiple osteochondromas (HMO) face higher risks of developing chondrosarcoma (cartilage cancer).

- Secondary osteochondromas: These occur in people who are suffering from other conditions such as Ollier’s disease or Mafucci’s syndrome. Both these syndromes affect cartilage and connective tissue.