The knee is one of the largest joints in our body and allows many different movements. The knee, however, can be susceptible to many types of injuries and arthritis processes. Arthritis is when the joint starts to swell, causing pain, stiffness and difficulty moving. Arthritis is typically results from trauma but can be caused by hereditary and genetic factors. Other types of arthritis can be a process of the body attacking itself, known as an autoimmune reaction.
Osteoarthritis
Osteoarthritis is a type of arthritis typically seen after some type of injury or infection. Within the knee joint, the bones are covered with a smooth layer of cartilage that allows for smooth joint movement but mainly acts as a shock absorber. Any damage to the cartilage can ruin that smooth surface and start to wear it down. The uneven surface of the cartilage can continue to thin and wear out. When the cartilage thins, it causes the nearby bone to start to thicken and even develop spurs; the spurring will lead to further irritation of the shock absorbers and can irritate the tissues that make synovial fluid (joint lubrication). In severe cases the cartilage can completely wear away, at which point the joint is bone on bone.
Varying Symptoms
The process of the arthritis and joint degeneration is accompanied by pain. Pain is the most common symptom and, unfortunately, the pain is not centered in one location; it can move, go away on its own, or be constant and sharp. Often, the pain is felt with movement, especially going up stairs. It is rare for osteoarthritis to cause pain with rest or at night, unless it is a well-progressed case. When the cartilage is no longer smooth, it can cause the joint to "lock up", feel stiff and not move as well. This might be a more predominant sign in the beginning, before pain starts. The irritation caused to the synovial tissues can cause them to produce more synovial fluid than is necessary, and some people can end up with mild to severe swelling (water on the knee).
Diagnosis
Since the symptoms can vary so much from one case to another, the best person to decide if you have osteoarthritis is your doctor. From there, your doctor will order blood tests and perhaps an X-ray or MRI to look for signs of the problem with imaging.
