The most worrisome complication of osteochondromas is malignant degeneration, which should be suspected with any new onset of pain or growth after skeletal maturity. In this case, the lesion is symptomatic because it is causing a tendinosis as it encircles and entraps the semitendinosus tendon, and substantially deviates the surrounding musculotendinous structures. 

Case courtesy of Dr. Aaron Schein.