The most common causes of knee pain in men are ligament injuries, meniscus tears, osteoarthritis, rheumatoid arthritis, etc. If the symptoms persist, it is recommended to consult a doctor in time. 1. Ligament injuries: If you are engaged in strenuous physical activities, it is easy to cause knee ligament injuries, which will lead to pain and swelling in the knee. 2. Meniscus tear: If you suffer from external impact or improper exercise, it may cause meniscus tear, which will cause knee pain. 3. Osteoarthritis: Degenerative changes in the articular cartilage may occur, which may be followed by osteophytes. The pain is mild at the beginning, but intensifies as the disease progresses. 4. Rheumatoid arthritis: this is an autoimmune disease, when the inflammation of the acute attack, there will also be redness, swelling and pain in the knee. Causes of knee pain in men are more causes, may also be associated with chondromalacia patella, bursitis, gouty arthritis and other diseases, if the symptoms continue to be unrelieved, it is recommended to go to the hospital in time to find out the cause of the disease, targeted treatment.