Medial compartmental osteoarthritis is a type of osteoarthritis (OA) of the knee. The knee itself is made up of three compartments:

  • lateral compartment, located on the outer side of the knee
  • medial compartment, located near the middle of the knee on the inner side
  • patellofemoral compartment, formed by the kneecap and part of the femur

Medial compartmental OA affects only the medial portion of the knee. OA of the knee that affects only the medial compartment or only the lateral compartment is also called unicompartmental arthritis. It’s also possible to have both medial compartmental and lateral compartmental arthritis at the same time.

Most types of OA are caused by wear and tear of specific joints, though there are some genetic forms as well. If you’re diagnosed with medial compartmental OA, the cartilage in your knee has undergone excessive use or injury.

According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, OA is the most common form of knee arthritis. Without diagnosis and treatment, medial compartmental OA can lead to serious complications that can affect your mobility. Learn more about this condition and the treatment options.

Symptoms of medial compartmental OA tend to develop over time. You may have pain in your knee and then notice that it gets worse, especially with activity. Eventually, the pain can stop you from everyday activities. You may also have pain and stiffness that is worse when you wake up in the morning.

Other symptoms can include swelling, or inflammation, in the knee area, as well as a knee that “locks up” after sitting. Vigorous activity can also make symptoms worse.

The symptoms of medial compartmental OA are like other types of OA symptoms. Pain, stiffness, and inflammation are markers for all arthritis. The difference in medial compartmental types is that the symptoms are in the knee only.

OA itself occurs when the articular cartilage gets damaged. Articular cartilage is crucial. It acts as a cushion between the bones of a joint. Without this type of cartilage, the bones rub against each other when you move. This can irritate nerve fibers and cause pain and further damage. As a result of the damage, spaces between the joints may narrow. Bone spurs can also form on the bones in the knee.

Medial compartmental OA without lateral compartmental OA may be due to:

  • a traumatic injury that destroys articular cartilage in the medial compartment only
  • knee misalignment
  • certain activities performed over time on an injured or misaligned knee, causing further wear and tear
  • a meniscus injury, which is an injury to the piece of fibrocartilage between your thighbone and shinbone

Medial compartmental OA is first diagnosed with a physical exam. Your doctor will analyze your medical history and any prior issues or injuries you’ve had with your knee. Then they will check for possible misalignment.

X-rays are taken to view joint damage of the knee. This will also help your doctor determine whether OA has affected multiple compartments within the knee or if you have medial compartmental OA only.

For an accurate diagnosis, you may be referred to a sports medicine specialist, orthopedic surgeon, or rheumatologist. These types of doctors specialize in OA.

Treatment for medial compartmental OA requires a combination of medications and exercises. Weight loss can also help. Below are some specific treatment plans for people with arthritis of the knee.

OTC medication

Over-the-counter (OTC) medications may help alleviate your symptoms while making it easier to move around and perform everyday tasks. These drugs include acetaminophen (Tylenol), aspirin (Bayer, Bufferin), and ibuprofen (Advil, Motrin).

Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). It has the additional benefit of reducing pain-causing inflammation. NSAIDs are used less often for the treatment of OA, but they may help reduce your pain if you’re experiencing a lot of inflammation in the knee.

The downside to OTC medications is that they don’t stop future pain. The effects from these drugs wear off once you stop taking them.

Prescription medication

There are also topical medications that contain NSAIDs, aspirin, and counterirritants. Some are available OTC. Diclofenac (Voltaren-XR, Pennsaid) is available by prescription.

Prescription-strength pain relievers (opioids) may be used in extreme cases. These drugs can be habit-forming and may interfere with other medications you take. For this reason, opioids are both prescribed and used with caution.

Certain injections of the knee may also help. Hyaluronan injections work by mimicking a component of joint fluid that cushions the knee joints. Corticosteroids may offer pain relief, as well as reduced inflammation, and sometimes can have a prolonged benefit. Corticosteroid injections may only provide short-term relief, or no relief at all.


Regular exercise is essential to managing your overall health, but it also helps protect your bones and joints. Exercise may be difficult at first because of the pain. But remember, regular movements help condition knee joints while also strengthening muscles in the area. The key is to start off slowly and to gradually work your way up to longer workouts. Doing too much too soon can cause more pain and joint damage.

Low-impact exercises, such as walking, swimming, and cycling, are best for knee OA. For medial compartmental OA, you can also talk to your doctor about incorporating mini-squats, hamstring and quad stretches, and other knee-strengthening exercises to your routine. Strengthening the quad muscles, which are the muscles in your thigh, may help stabilize your knee and reduce or prevent pain.

Learn more: Maintaining fitness with osteoarthritis of the knee »

Weight loss

Losing weight can help alleviate excess pressure placed on the knees and other joints in the body. In fact, according to the University of California, San Francisco, weight loss is the best nonsurgical option for this type of OA. If you’re overweight, talk to your doctor about safe ways to manage extra pounds. Exercising and making changes to your diet can help.

Your doctor may also recommend an unloader brace for your knee for added support. This may be especially helpful if your OA is caused by knee misalignment. The downside is that these braces sometimes need to be custom-made and can be costly.

For some people, medications and lifestyle changes may not be enough to stop the damage already done to their knees from medial compartmental OA. In such cases, knee replacement surgery might be necessary. A surgery decision is based on your age, severity of pain, and your overall activity level.

Reduced mobility from OA of the knee may require physical therapy. You may also need assistive devices, such as crutches or a wheelchair.

OA is a permanent condition. Once your joints are damaged, they won’t come back. Forms of OA, like medial compartmental OA, may be managed to prevent further damage.

Proper treatment and lifestyle changes can reduce the need for knee replacement surgery. They can also improve your quality of life and decrease the need for mobility devices. Though it may be tough at first, staying active can also go a long way in managing medial compartmental OA.