<s>[INST] My 16 year old son hit his knee about a month and a half ago. He had xrays at first and there was nothing broken.  Now he has a hard bump in that place.  It only hurts when pressure is put on it.  What do you think that hard bump is? Thanks so much for your help! [/INST] Hello,Thank you for using Healthcaremagic.I read your question and understood your concern.I think this bump is a hematoma ( blood collection) that the body did not absorbed and it is hardened now. We call it organized hematoma or ossified hematoma. It will need masage and give more time the body to absorbeDr. Selmani </s>