Author: Jack Andringa-Bate
Knee pain is one of the most common reasons for people to visit a Physiotherapist and one of the most prevalent lower limb conditions. If you are over the 40 and have not recently changed your activity levels or had a traumatic injury, a swollen and painful knee may be contributed to by knee osteoarthritis. Although this diagnosis may seem scary and threatening, the prognosis is often more favourable than you think! In addition, a diagnosis of knee osteoarthritis does not mean you have to stop physical activity altogether, in fact just the opposite is often true.
Essential Anatomy
The knee is a hinge joint formed by the articulation of the femur bone of the thigh with the tibia bone of the lower leg. A joint capsule surrounds this articulation and this is filled with fluid (more on this shortly), giving rise to medial and lateral compartments that are also supported by multiple ligaments. All this adds up to a very stable joint and this structure allows us to flex and extend our knee easily while preventing a large amount of movement in the medial or lateral (side to side) directions. The patellofemoral joint, which is the joint formed between your knee cap and the femur, is also included.
The surfaces of bones that meet in joints in our bodies are covered with what is known as articular cartilage. This cartilage is an adaptation that helps to ensure the bones can glide over each other with very little friction. This process is further aided by synovial fluid, a special fluid that exists in our joints to nourish them and aid in movement. It’s important to note that articular cartilage has little to no direct blood supply. Since blood is regenerative, this means that the articular cartilage is very poor at regenerating and repairing.
What causes knee osteoarthritis
At its heart, knee osteoarthritis involves the thinning of the articular cartilage that covers the surface of the bones of the knee joint, accompanied by inflammation and pain. This is an extremely complex process that is contributed to by many factors. Whilst it is often easy to simply blame things such as wear and tear on the knee joint, the reality is that articular cartilage thinning is both a physical and a biological process. This means that many factors are at play in the development of knee osteoarthritis, some that we can control (such as body weight and diet), and some that we cannot (like our genes). In some cases, previous injury to the knee, such as a meniscus injury or ACL rupture, can lead to arthritis over time as these injuries influence the biomechanics of the knee.
Although the articular cartilage does not have very good capacity to regenerate, this does not mean that thinning of the articular cartilage is inevitable or that it is unable to respond to stress. The human body is a dynamic and adaptable system and it has been demonstrated in many tissues in the body that they can adapt and change in response to the stresses that they are subjected to. For example, studies that have shown running at moderate to high levels may actually be protective with regards to the health of knee cartilage. We must be careful to assume that a knee joint has become “worn out” due to overuse and that this means we need to “protect and save” the knee.
Often when people are diagnosed with osteoarthritis, it is because they have received an X-ray that has demonstrated changes within their knee. Radiographic changes that can be seen on X-ray, often considered a gold standard for diagnosing osteoarthritis, are actually quite poorly correlated with pain. This means that in some people there may be a high degree of radiographic evidence of degeneration but that this individual may not have severe pain. Conversely, some people may have minimal signs of radiographic evidence of degeneration while experiencing a high degree of pain. This highlights that pain is a complex and multidimensional process. It is important in osteoarthritis to remember that what you see on your x-ray or MRI result does not necessarily dictate how you will experience osteoarthritis, it is only one piece of a much larger puzzle.
Physiotherapy treatment for knee osteoarthritis
Owing to its high prevalence there is a multitude of treatment options for someone with knee osteoarthritis. These range from pharmacological aids for pain relief, to exercise therapy and even surgery. In most cases, conservative management is considered as the first-line treatment for osteoarthritis. Conservative management is any treatment that avoids invasive surgical procedures. This may include a number of treatments including education, weight loss, and activity modification, therapeutic exercise, and pain relief (often in conjunction with exercise).
Exercise is very important in knee osteoarthritis for several reasons. Research is constantly being updated in this area but one thing that is for certain is that strong muscle help to support painful joints. Exercise can help to improve tissue capacity, meaning that it can make your body stronger and more resilient to stress. Physiotherapists are experts at identifying which exercises can be used to specifically improve your tissue capacity. When performed consistently, exercise can enable people to continue to do the activities they enjoy, often without pain. It is also important to note that exercise has anti-inflammatory effects which over time, help to decrease the inflammation and pain that occurs with knee osteoarthritis.
While exercise is undoubtedly important in knee osteoarthritis, the devil is often in the dosage. This is especially important when you first begin your rehabilitation when knee pain can often be stirred. At these times, the assistance of a professional such as a Physiotherapist can be crucial, as they will be able to offer support and guidance on the appropriate frequency, timing, intensity, and type of exercise. Examples of exercises for knee osteoarthritis include:
Mobility –
Knee range of motion exercises may be useful to reduce swelling and pain in the knee.
Control –
Balance and proprioception (body awareness) exercises may be useful to improve control and balance in the knee joint, which are often impaired in the presence of pain.
Strength –
Strength exercises such as squats, lunges, and bridges will help to build tissue capacity to support the knee and may help to facilitate getting you back to doing the physical activities that you enjoy.
Summary
In summary, remember these 3 things about knee osteoarthritis:
- The causes of knee osteoarthritis are complex and include physical and biological processes, some of which we can control, and some of which we cannot.
- A diagnosis of knee osteoarthritis does not necessarily mean your knee is worn out and that you cannot continue to lead a healthy, active lifestyle
- Conservative management, including Physiotherapy led therapeutic exercise, is effective as a first-line treatment in reducing symptoms and improving functional outcomes (i.e. the activities you enjoy doing) in many people.
If you are experiencing knee pain, book in with your physiotherapist for a thorough assessment using this link – FREE INITIAL ASSESSMENT. Once the cause has been identified, the road to recovery can begin.
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