Arthritis can occur in any joint, but occurs most often in weight–bearing joints such as the knees and hips. There are three major types of arthritis that can affect the knee, which are osteoarthritis, rheumatoid arthritis and post-traumatic arthritis; osteoarthritis is the most common form of arthritis in the knee. Osteoarthritis is the “wear and tear” of the cartilage in the knee. As the cartilage wears away, it becomes frayed and rough, and the protective space between the bones decreases. This can become very painful as bone begins rubbing on bone and most often is seen in people 50 years of age and older. Common symptoms of arthritis in the joint can include swelling, pain, stiffness and decreased range of motion. There are several proactive steps you can take to help alleviate knee pain. Stretching the calf, hamstring and quadriceps muscles takes pressure off your knees and kneecaps. Weight loss can also be beneficial. People with knee arthritis can lessen their pain by about 20 percent with every 10 pounds they lose. Wearing shoes that are comfortable, supportive and have good cushioning can help alleviate pressure being placed on the knee joint. Having strong core muscles in your lower abdomen and lower back improves posture, which lessens the pressure on your knees.