Knee bone protruding this condition may be due to gout, but may also be rheumatoid arthritis, osteophytes and other causes. 1. Gout: gout is the deposition of urate crystals in the joints and surrounding soft tissues, triggering episodes of joint swelling and pain. Long-term aggregation of urate crystals can form gout stones, commonly found in articular cartilage, bursa, olecranon, periarticular tissues and other places, causing corresponding symptoms. When gout stone occurs in the knee joint, the knee bone can appear to protrude. 2. Rheumatoid arthritis: Rheumatoid joints can involve the peripheral joints of the wrist, fingers, knees, ankles, etc. and cause joint swelling, joint pain and joint deformity, therefore, the protruding of the knee bone may also be caused by rheumatoid arthritis. 3. Osteomalacia: Osteomalacia is a common disease in the middle-aged and elderly, and joint pain and joint deformity can occur when osteomalacia occurs in the joints of the knee, ankle, wrist and other joint parts. Therefore, the protruding knee bone may also be caused by osteophytes. There may be other reasons for the protruding knee bone, so it is recommended that patients go to the relevant departments of regular hospitals for detailed counseling.