Osteochondroma is the most common noncancerous bone growth. Most often, it affects the long bones in the leg, the pelvis, or the shoulder blade. An osteochondroma is a benign ( noncancerous) tumor that develops during childhood or adolescence. Multiple osteochondromatosis ( MO) is a rare genetic disorder associated with serious complications that may significantly affect the health- related quality of life of anyone having the disorder. The identified mechanism behind solitary osteochondromas is the homozygous deletions of the EXT1 gene. Osteochondroma is an overgrowth of cartilage and bone that happens at the end of the bone near the growth plate. Osteochondroza cantarinei. Osteochondrosis is almost exclusively found in children and teenagers up to around age 20. In about 10– 15% of all cases no genomic alterations are detected. An osteochondroma is made up of both bone and cartilage. Osteochondrosis is a family of orthopedic diseases of the joint that occur in children, adolescents and other rapidly growing animals, particularly pigs, horses, dogs, and broiler chickens. The mechanism behind the formation of multiple osteochondroma is large genomic deletions of EXT1 and EXT2 genes. Osteochondroses can also occur as a result of athletic activity and sports injuries. However, the exact cause of osteochondroma is unknown. It is an abnormal growth that forms on the surface of a bone near the growth plate.