What are the potential causes of knee swelling and pain?

There are many reasons why your knee might swell and hurt. One common cause is an injury. When you fall or twist your knee, ligaments or cartilage can be hurt. This can lead to extra fluid in the knee, known as knee effusion. Sometimes, a tear in the meniscus (the cushion in your knee) can cause pain and swelling. Infections inside the joint, called septic arthritis, can also cause a swollen, warm, and painful knee. Some people develop arthritis, which is wear-and-tear damage (osteoarthritis) or an immune system problem (rheumatoid arthritis), and this can lead to chronic knee pain and swelling. In addition, conditions like gout can cause sudden and severe knee pain along with swelling. Another possibility is bursitis, like prepatellar bursitis, which happens when the small fluid-filled sacs near the knee become inflamed from too much kneeling or repetitive pressure. Overall, these problems can cause your knee to feel stiff, swollen, and painful, and it is important to see a healthcare provider to help find the exact reason and the best way to feel better.