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Introduction

Knee Pain

Knee Osteoarthritis

Osteoarthritis (OA) is a common problem for many people after middle age. OA is sometimes referred to as degenerative or wear and tear arthritis. OA commonly affects the knee joint. Although OA has no cure, there are ways to treat it so patients have less pain, better movement, and enhanced quality of life.

The main problem in OA is degeneration of the articular cartilage. Articular cartilage is the smooth lining that covers the ends of the leg bones where they meet to form the knee joint. The cartilage gives the joint freedom of movement by decreasing friction.

When the articular cartilage degenerates, or wears away, the bone underneath is uncovered and rubs against bone. Small outgrowths called bone spurs may form in the joint.

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Causes

Years of repeated strain on the knee leading to wear and tear is the most common caue of osteoarthritis in the knee. Other causes include: 

  • Earlier knee injury: Fractures of the joint surfaces, ligament tears, and meniscal injuries can all cause abnormal movement and alignment, leading to wear and tear on the joint surfaces.

  • Genetics

  • Obesity: Having a higher body mass puts greater strain on the knee. Losing 10 pounds can reduce the risk of knee osteoarthritis by 50 percent.  

  • Problems in the subchondral bone: Normally, the articular cartilage protects the subchondral bone (the layer of bone just below the articular cartilage). But some medical conditions can make the subchondral bone too hard or too soft, changing how the cartilage normally cushions and absorbs shock in the joint.

Symptoms
  • Pain, swelling and stiffening of the knee

  • Pain worsens after activity like walking

 

Knee osteoarthritis develops slowly over several years, so symptoms gradually worsen.

  • Early stage: Your knee does fairly well while walking, then after sitting for several minutes your knee becomes stiff and painful

  • Intermediate stage: As the condition progresses, pain can interfere with simple daily activities

  • Late stage: The pain can be continuous and even affect sleep patterns

Diagnosis

The diagnosis of OA can usually be made on the basis of the initial history and examination.

X-rays can help in the diagnosis and may be the only special test required in the majority of cases. X-rays can also help doctors rule out other problems, since knee pain from OA may be confused with other common causes of knee pain, such as a torn meniscus or kneecap problems. In some cases of early OA, X-rays may not show the expected changes.

Magnetic resonance imaging (MRI) may be ordered to look at the knee more closely. An MRI scan is a special radiological test that uses magnetic waves to create pictures that look like slices of the knee. The MRI scan shows the bones, ligaments, articular cartilage, and menisci. The MRI scan is painless and requires no needles or dye.

If the diagnosis is still unclear, arthroscopy may be necessary to actually look inside the knee and see if the joint surfaces are beginning to show wear and tear. Arthroscopy is a surgical procedure in which a small fiber-optic TV camera is inserted into the knee joint through a very small incision, about one-quarter of an inch long. The surgeon can move the camera around inside the joint while watching the pictures on a TV screen. The structures inside the joint can be poked and pulled with small surgical instruments to see if there is any damage.

Non-surgical treatments

OA can't be cured, but therapies are available to ease symptoms and to slow down the degeneration. Recent information shows that mild cases of knee OA may be maintained and in some cases improved without surgery.

  • Taking pain relievers: Your healthcare provider may recommend taking pain relievers (non-steroidal anti-inflammatory medications, or NSAIDs) to help reduce pain and swelling in your knee. Acetaminophen can be used as an alternative if you cannot tolerate NSAIDs or are allergic.

  • Glucosamine and chondroitin sulfate: These supplements seem to have nearly the same benefits as anti-inflammatory medicine with fewer side affects. Many doctors feel the research supports these supplements and are encouraging their patients to use them.

  • Cortison injection: Cortisone is a powerful anti-inflammatory medication, but it has secondary effects that limit its usefulness in the treatment of OA. Multiple injections of cortisone may actually speed up the process of degeneration. Repeated injections also increase the risk of developing a knee joint infection, called septic arthritis. Any time a joint is entered with a needle, there is the possibility of an infection. Most physicians use cortisone sparingly, and avoid multiple injections unless the joint is already in the end stages of degeneration, and the next step is an artificial knee replacement.

  • Hyaluronic acid injection: Doctors inject three to five doses into the joint over a one-month period. The medicine helps lubricate the joint, ease pain, and improve people's ability to get back to some of the activities they enjoy. These injections are less effective for older adults and severe OA.

  • Physical therapy: You will learn ways to calm pain and symptoms, which might include the use of rest, heat, or topical rubs. You will also be taught how to protect the arthritic knee joint by modifying your activities. Range-of-motion and stretching exercises will be used to improve knee motion.

  • Walking aids: This may include shock-absorbing insoles, a cane or walker, a knee unloading brace, or a heel wedge

Surgery