Hi,Welcome with your query to HCM virtual Clinic. I reviewed all the details of your query. Based on the facts of your query,the cause of the sore knee hard lump seems to be-Painful PrePatellar Bursitis(Housemaids Knee) with accompanied Patellar subluxation /or it could be Synovitis as you had history of knee trauma which led to Patellar Subluxation,formed due to hard hit ,as you don t deny having hard hit. Would suggest USG/Xray knee left/right to fix this ambiguity. As I don t have direct information and as you haven t yet shown to any doctor except your cardiologist,I would suggest to take Second Opinion from your Orthopedic Surgeon/ or General Surgeon.He would investigate /check and treat it accordingly. Hope this reply would help you to plan treatment with your doctors and resolve your worries. Will appreciate writing excellent review and feedback comments to help the needy patient visitors like you at HCM. Welcome any further query and information in this regard. Contact at My HCM Clinic,with direct Premium question for further suggestions if need be. Good Day!! Dr.Savaskar M.N. Senior Surgical Specialist M.S.Genl-CVTS