A lump of flesh bulging at the knee may be caused by trauma, cystic lesion, tumor lesion, knee joint effusion and other reasons. 1. Trauma: some patients in the knee trauma in the local wound healing process, the abnormal proliferation of inflammatory granulation tissue to form hyperplastic scars, the patient may appear in the knee bulge a pile of meat. 2. Cystic lesions: common sebaceous cysts, meniscus cysts, bone cysts and other diseases, can cause patients to bulge a pile of meat at the knee. 3. Tumor lesions: such as benign and malignant tumors of the skin, lipoma, osteochondroma, osteosarcoma and other tumor lesions caused by local hyperplasia, the patient may appear to bulge a pile of meat at the knee. 4. Knee joint effusion: such as knee synovitis, infection and other diseases can cause suprapatellar bursa effusion, the patient may appear at the knee bulging a pile of meat, touching the fluctuation feeling. There may be other reasons for the bulging of 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.