A lump inside the lower part of the knee may be a normal bony protrusion or it may be due to osteophytes, bone or soft tissue tumors, or bursitis, Local scarring and hyperplasia and other diseases. 1. Normal bony prominences: there are normal bony prominences such as tibial tuberosity below the knee joint of human body, which are more obvious in thin people. 2. Osteomalacia: due to osteophytes, especially the formation of localized bony prominence, patients may have a lump below the knee. 3. Bone or soft tissue tumors: such as osteochondroma, osteosarcoma, lipoma and other neoplastic diseases, patients may also have a lump below the knee. 4. Bursitis: due to long-term friction and other factors lead to aseptic inflammation of local bursa and other tissues, patients may have a lump below the knee. 5. Localized scar hyperplasia: often due to previous trauma, the patient belongs to the scarred body, after healing in the wound above the formation of hyperplastic scars. There may also be other reasons for a lump below the knee, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.