Osteochondroma

Osteochondroma
Other names	Osteocartilaginous exostoses
Lateral radiograph of the knee demonstrating ossification in the peritendinous tissues in a patient with osteochondroma.
Specialty	Orthopedics

Osteochondromas are the most common benign tumors of the bones.^[1][2] The tumors take the form of cartilage-capped bony projections or outgrowth on the surface of bones (exostoses).^[3][4] It is characterized as a type of overgrowth that can occur in any bone where cartilage forms bone. Tumors most commonly affect long bones about the knee and in the forearm.^[1][3] Additionally, flat bones such as the pelvis and scapula (shoulder blade) may be affected.^[5]

Hereditary multiple exostoses usually present during childhood. Yet, the vast majority of affected individuals become clinically manifest by the time they reach adolescence.^[3][6] Osteochondromas occur in 3% of the general population and represent 35% of all benign tumors and 8% of all bone tumors. The majority of these tumors are solitary non-hereditary lesions and approximately 15% of osteochondromas occur as hereditary multiple exostoses preferably known as hereditary multiple osteochondromas (HMOs).^[4][7]

Osteochondromas do not result from injury and the exact cause remains unknown. Recent research has indicated that multiple osteochondromas is an autosomal dominant inherited disease. Germline mutations in EXT1 and EXT2 genes located on chromosomes 8 and 11 have been associated with the cause of the disease.^[8]

The treatment choice for osteochondroma is surgical removal of solitary lesion or partial excision of the outgrowth, when symptoms cause motion limitations or nerve and blood vessel impingements.^[4][7] In hereditary multiple exostoses the indications of surgery are based upon multiple factors that are taken collectively, namely: patient's age, tumor location and number, accompanying symptomatology, esthetic concerns, family history and underlying gene mutation.^[1][3] A variety of surgical procedures have been employed to remedy hereditary multiple exostoses such as osteochondroma excision, bone lengthening, corrective osteotomy and hemiepiphysiodesis. Sometimes a combination of the previous procedures is used.^[3] The indicators of surgical success in regard to disease and patient characteristics are greatly disputable.^[3] Because most studies of hereditary multiple exostoses are retrospective and of limited sample size with missing data, the best evidence for each of the currently practiced surgical procedures is lacking.^[3]