A 26 years old lady complained to her GP of aching pain in both knees on and off for the last few years. The GP requested for an x-ray to be done.
X-ray showed multiple bony projections arising from the medial aspect of his tibias bilaterally as well as medial and lateral aspect of lower femurs. These projections are known as exostoses.
An exostosis (plural: exostoses) is the formation of new bone on the surface of a bone. Some people called it osteochondroma. These are benign growths of bone extending outwards from the surface of a bone. It can occur in any bone. It can be solitary or multiple, sessile or pedunculated.
The number of exostoses and the bones on which they are located vary greatly among affected individuals. The exostoses are not present at birth, but approximately 96% of affected people develop multiple exostoses by the time they are 12 years old. Exostoses typically form at the end of long bones and on flat bones such as the hip and shoulder blade. Once they reach adult height and their bones stop growing, the development of new exostoses also usually stops.
Multiple exostoses can disrupt bone growth and can cause growth disturbances of the arms, hands, and legs, leading to short stature. Often these problems with bone growth do not affect the right and left limb equally, resulting in uneven limb lengths (limb length discrepancy). Bowing of the forearm or ankle and abnormal development of the hip joints (hip dysplasia) caused by exostoses can lead to difficulty walking and general discomfort.
Multiple exostoses may also result in pain, limited range of joint movement, and pressure on nerves, blood vessels, the spinal cord, and tissues surrounding the exostoses.
Hereditary multiple exostoses is a condition in which people develop multiple exostoses. Exostoses are typically benign; however, in some instances these tumours may become malignant (cancerous). It is estimated that people with hereditary multiple exostoses have a 1 in 20 to 1 in 200 lifetime risk of developing cancerous exostoses (sarcomas).