Exostosis

An exostosis (pl. exostoses) is a benign (non-cancerous) new growth projecting from the surface of a bone, informally known as a bone spur. Exostoses can cause chronic pain ranging from mild to severe, depending on the shape, size, and location of the lesion, though most are asymptomatic and are found by chance on plain x-ray taken for other reasons. Occasionally, an exostosis can be potentially life-threatening.

When used in the phrases "cartilaginous exostosis" or "osteocartilaginous exostosis", the term is considered synonymous with osteochondroma. Some sources consider the two terms to mean the same thing even without qualifiers, but this interpretation is not universal.

Osteomyelitis, a bone infection, may leave the adjacent bone with exostosis formation. Charcot foot, the neuropathic breakdown of the feet seen primarily in diabetics, can also leave bone spurs that may then become symptomatic.