There are many causes of knee pain. In people over the age of 50, by far the most common cause of knee pain is osteoarthritis, which is wear and tear of the knee. In younger people, it's going to be more musculoskeletal injuries or repetitive stress injuries. And knee osteoarthritis in people over 50. And everyone can develop knee meniscus tears, muscle injuries that refer into the knee, patellar tendinitis, patellofemoral syndrome- the way the patella tracks within the knee, bursitis, you can strain the ligament. All sorts of musculoskeletal injuries can lead to knee pain. In addition, knee pain can be a presenting symptom for a more systemic problem such as lyme disease or rheumatoid arthritis. This is why it’s so important if you have knee pain to go to a doctor and get checked out so that the underlying cause can be identified and promptly treated.

What are the Symptoms of Knee Pain that Indicate Arthritis?

When knee pain is caused by arthritis, people are generally presented with dull, achy pain in the knee. It is often stiff in the morning and feels a little better as you get moving. If you walk for too long, the knee will often be painful. Depending on whether or not the arthritis is in the medial or lateral components, the anterior or front of the knee, depending on where the arthritis is it may be more painful with going up steps or going down steps. Down steps indicates more that it is behind the knee cap, behind the patella, and going up stairs is more consistent with arthritis in the medial or lateral components of the knee.

In general it may be dull and achy, it may start to lock a little bit or catch. There may be episodic flares of knee pain where it gets swollen and then gets a little better, and it fluctuates a little bit as time goes on. Often colder weather or fluctuations in the pressure outside will affect the way that someone experiences knee pain as well. It is important to recognize that there is no one specific symptom that one will have with knee arthritis, but rather a constellation of them and then putting that into the overall clinical picture as well.

How is Knee Pain from Arthritis Diagnosed?

The diagnosis of knee pain from arthritis begins with a history and physical examination. During the history, people with knee pain from arthritis will often have dull achy pain, often it’s a little more stiff in the morning and it feels a little better as you get going. If you go for a long walk there may exacerbation of the pain. Going up and down stairs depending on where the arthritis is may also make that more painful. Sometimes when people sit for a long time, they feel like they have to stretch their leg out because the knee will get stiff and achy and there may be episodic flares of knee pain with arthritis as well.

During the physical examination, you may notice some crepitus and crunching as you move the knee around. And there will be some different provocative maneuvers. A lot of the physical examination will also be ruling out other causes of knee pain and to make sure there is no acute meniscal tear, ligament strain, or other more acute kinds of injuries. X-rays, and MRIs, and other imaging studies will typically show arthritis in the knee, but it’s important to realize that x-rays or the MRIs may show arthritis, but that does not necessarily mean that arthritis is causing the symptoms either.

So it’s important to always put imaging studies in proper context. That context is that it's one piece of the diagnostic puzzle but not the entire diagnostic puzzle. It’s not uncommon to see a patient who has pain on one knee, say pain in the right knee, but X-rays of both knees shows the same amount of arthritis on both knees. The difference is that in one knee, there has been an inflammatory response to the arthritis and now that knee is symptomatic. So that’s the knee that we need to address. That is just one example of why it’s important to take your imaging studies in that appropriate context.

Dr. Grant Cooper is a physiatrist with several years of clinical experience, specializing in the non-surgical treatment of spine, joint, and muscle pain. He is the Co-Founder and Co-Director of Princeton Spine and Joint Center and the Co-Director of the Interventional Spine Program. Dr. Cooper has authored and edited 15 books.