Hello, Thanks for your query. This hard nodule could be due to haematoma formation (collection of blood) which might get fibrosed or calcified.. Possibilities that may need to be considered include bony outgrowth, growths from underlying connective tissue etc. I would suggest getting this evaluated by an orthopedician for an accurate diagnosis and appropriate management. You may get the X-ray of the area affected and FNAC (fine needle aspiration cytology) of lump under his/her guidance. I do hope that you have found something helpful and I will be glad to answer any further query. Take care