Welcome to part one of our three-part blog series on Knee Osteoarthritis (OA). This series will tell you everything you need to know about the condition; the symptoms, stages, treatments, and bracing options available to you. In part one we will discuss OA is, it’s risk factors, symptoms and stages of progression.
What is Knee Osteoarthritis?
Osteoarthritis (OA) is a degenerative disease affecting the joints. With 16 million people impacted by osteoarthritis, it is considered to be the most common cause of arthritis pain. 1 million Canadians live with knee OA, with one out of ten people over 60 years of age is affected by the condition. However its onset is being detected 16 years earlier than it was in the 1990s.
Osteoarthritis is known as a “wear and tear” disease. The symptoms people experience are caused by a loss of or breaking down of cartilage in the knee, which leads to a narrowing of the space in the joint. This loss of joint space progresses as time goes on, leading to bone spurs and decreased movement.
Interested in learning more about OA treatments? Read the second blog post in the series Knee Osteoarthritis: Non-Surgical Treatments That Work.
Causes and Risk Factors
Knee OA can develop as a result of a number of factors. Age is the most common risk factor associated with OA. It is important to remember that, while age does not cause knee OA, older adults (especially women) are still most affected due to the degenerative nature of the disease. It is estimated that 85% of Canadians over the age of 70 will have osteoarthritis. Other risk factors include:
- Altered knee biomechanics
- Previous injury or trauma
- Repetitive stress injuries
There are many symptoms of knee osteoarthritis, and their severity depends on how advanced your condition is. While you may not have every symptom associated with knee osteoarthritis, you could have osteoarthritis of the knee if you have any of these symptoms:
Crepitus is the medical term for that grinding, creaking, crunching, or grating sensation you may feel or hear when moving or bending your knee. Depending on how advanced your knee osteoarthritis is, you may feel or hear (or sometimes both) these sounds/sensations when moving the knee joint.:
Pain, tenderness, or soreness is often felt on the inside of the knee (medial knee) with osteoarthritis. This is because your body distributes your weight straight down, putting added pressure on the inside of the knee joint. However, some people do experience OA symptoms on both sides of their knee or just the outside of the knee joint. OA pain is usually worse at the end of the day and improves with rest. With knee OA you may feel pain or sensitivity when:
- Kneeling down
- Walking uphill or downhill
- Walking up stairs or down stairs
- Bending your knee
While pain associated osteoarthritis can get better with rest, too much rest will lead to stiffness in the knee joint. The stiffness usually lasts for a few minutes and subsides with movement and gentle stretching. If you’ve noticed that your knee becomes stiff after sitting for a while, or it’s most stiff when you wake up in the morning, you may have knee OA. With knee osteoarthritis your knee may feel stiff:
- For short periods in the morning
- After prolonged rest
- After sitting for a long time
Loss of Mobility
Knee OA can result in a loss of daily functioning as your knee is not moving as freely or as much as it normally would. The pain, tenderness, and stiffness mean many people with OA see a decrease in their mobility, this can make it difficult to:
- Get in and out of chairs
- Get in or out of cars
- Walk up or down stairs
Decrease in Muscle Power
OA can lead to some loss of muscle power with muscle loss or wasting near the knee joint. While muscle wasting is a more extreme symptom, many people with OA still experience:
- Weak muscles near the knee joint
- Knee giving out or giving way
- Joint instability
- Loss of muscle power
You may also experience warmth and swelling of the knee. With knee OA you may experience:
- Swelling inside the actual knee joint space
- Swelling of the bursa (fluid filled sacks near the knee
Learn more about treating OA in the second blog post in this series Knee Osteoarthritis: Non-Surgical Treatments That Work.
Knee Osteoarthritis Stages
Osteoarthritis is a degenerative condition that sees the cartilage in the knee slowly wear away. The cartilage in the knee joint becomes rough and breaks down over time, causing an overgrowth of the bone underneath. OA gradually develops over many years and can go undetected until you reach the later stages. The progression of OA is measured in four stages.
Stage One – Minor – Little or no Pain or Discomfort
In stage one, there is already a small loss of cartilage (around 10%). Osteophytes, small outgrowths of bone, may also start growing in the knee joint. While there is some cartilage loss, there is little to no narrowing of the joint space between the bones.
Stage Two – Mild – Some Pain and Joint Stiffness
Stage two sees a continuing loss of cartilage and noticeable osteophyte growth. While the space between the joints (joint space) remains healthy, the places where the bones make contact starts to harden, along with the surrounding tissues. Damage to the knee joint at this stage is still minor; the bones are not rubbing or scraping against each other.
Stage 3 – Moderate – Pain, Discomfort, and Swelling
In stage three, there is a notable loss of cartilage and the joint space has noticeably narrowed. This stage also sees the joint becoming swollen and inflamed.
Stage 4 – Severe – Intense Pain, Discomfort, Loss of Mobility
Stage four is the most advanced with 60% of knee cartilage worn away. The joint space is significantly narrowed with the bones touching each other. The friction caused by the bones rubbing against each other causes significant inflammation. Patients at this stage of OA typically see the growth of more osteophytes, experience intense pain and in very severe cases the bones may become deformed.
It is possible to have stage four OA with minimal to no pain at all. That’s why, if you think you might have osteoarthritis of the knee, it’s best to book an appointment with a qualified physical therapist to get a full assessment.