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  • Writer's pictureDaniel Selin

Knee osteoarthritis

Knee osteoarthritis, knee arthritis, knee wear and tear, joint disease, joint wear and tear, knee degeneration, knee pain, knee ache, morning stiffness, stiffness, aging.

Polven tutkiminen, fysioterapia

Osteoarthritis or arthrosis, is the world's most common joint disease, and its prevalence increases with age. Although the root cause of rheumatoid arthritis is unknown, the disease involves more degradative than constructive events at the cellular and molecular level in the joint's cartilage and extracellular matrix. This leads to changes throughout the joint and surrounding tissues, ultimately resulting in significant functional changes in a person's movement and activity. Rheumatoid arthritis is most commonly found in the knees, hips, fingers and toe joints, and the facet joints between the spinal vertebrae.

Osteoarthritis can be broadly divided into two groups: primary and secondary rheumatoid arthritis. Primary osteoarthritis refers to joint degeneration without an apparent underlying cause, while secondary osteoarthritis is the result of either an abnormal force concentration in the joint, such as a traumatic injury, or an abnormal joint cartilage, such as in rheumatoid arthritis.

This text provides a closer look at knee osteoarthritis and delves into its underlying causes and treatment principles.


Overview of joint cartilage physiology

Joint cartilage is located at the ends of the bones that form a joint, and its main function is to absorb shock and facilitate gliding between the bones. It consists mainly of collagen and proteoglycans, which bind water molecules. Cartilage lacks blood vessels and nerves, so its metabolism and nutrient supply rely on the pressure changes that occur within the joint.

When the cartilage is compressed, fluid is squeezed out into the joint space, and when the load is released, the negative charge of the proteoglycans generates an osmotic pressure that draws nutrient-rich fluid back into the cartilage. Thus, joint loading is a key factor that affects the structure and metabolism of the cartilage. Moderate joint loading can maintain and enhance the properties of the cartilage.



The symptoms of knee osteoarthritis often begin with morning stiffness and pain, which then progresses and worsens with physical activity. When the knee is painful, it can also swell, and over time the joint itself may grow larger.

The knee is painful after prolonged periods of inactivity, and getting started with movement becomes more difficult. There is often a cracking or popping sound in the joint when the knee is bent or straightened. These joint sounds are completely harmless and are due to the weakened sliding properties of the joint cartilage. There doesn't seem to be a correlation between the loudness of joint sounds and pain, although they often worry people with knee osteoarthritis.

Typical symptoms of knee osteoarthritis are:

  • Pain during movement and when getting started with movement

  • Stiffness in the knee, especially in the morning

  • Loss of range of motion

  • Joint sounds

  • Pain after prolonged sitting or lying down

  • Joint enlargement

  • Knee pain that disrupts sleep

  • Dull, constant pain

  • Difficulty bearing weight on the affected leg



Osteoarthritis is the most common joint disease worldwide, and knee osteoarthritis is the most typical type of osteoarthritis. The disease primarily affects men and women over 45 years old, with slightly more women affected than men. Osteoarthritis can lead to increased pain sensitivity and reduced function, although not all osteoarthritis findings are painful. In fact, in one study, only about 15% of patients with knee osteoarthritis findings on X-rays had knee pain or changes in function.

Knee osteoarthritis is classified as primary or secondary based on its cause: Primary knee osteoarthritis is the result of degeneration of joint cartilage without a known cause. This is thought to be a result of age and wear and tear, where there are more destructive than constructive events occurring in the joint cartilage.

Secondary knee osteoarthritis is the result of degeneration of joint cartilage due to a known cause. Possible causes of secondary knee osteoarthritis include:

  • Obesity

  • Joint immobility or instability, for example due to injury

  • Abnormal joint alignment, either congenital or due to injury

  • Previous joint injury, such as a fracture to the joint surface

  • Congenital defects

  • Immobilization and loss of mobility

  • Family history and genetic inheritance

  • Metabolic factors

  • Abnormal anatomy

Normally, joint cartilage is in a balanced state of chemical reactions, but when osteoarthritis develops, the reactions become disrupted, leading to changes in collagen in the cartilage. This leads to disorganized collagen structure and reduced cartilage elasticity, resulting in cracks in the cartilage and eventually erosion. The damaged cartilage recovery process is disrupted, and the cartilage continues to wear away. As the cartilage wears away, the bony surfaces begin to damage, and this leads to the development of bone spurs, which further expand and stiffen the joint. At the same time, there is often ligament laxity and muscle wasting.



The primary treatment for knee osteoarthritis is conservative treatment. This includes a combination of pharmacological and non-pharmacological pain management methods, as well as a gradually increasing exercise program designed by a physiotherapist to improve the knee's biomechanical properties. The goal of treatment is to alleviate pain and improve function and work capacity. Strengthening the muscles surrounding the joint and improving mobility are of paramount importance in knee osteoarthritis. This is achieved through a precise, individualized exercise program that often includes mobility-enhancing and maintenance exercises, as well as manual therapy. In the early stages, heavy or stressful exercise can exacerbate symptoms, so training should be started moderately.

Drug therapy for osteoarthritis aims to alleviate symptoms, as there is no medication that cures osteoarthritis. However, this is an important part of overall rehabilitation to ensure that exercise is carried out without major complications. Pain and anti-inflammatory medications are the primary pharmacological options, but if these do not produce the desired results, opioids or intra-articular corticosteroid or hyaluronate injections may be tried. In such cases, it is advisable to consult a physician specializing in osteoarthritis and pain management.

Joint replacement surgery is considered when conservative treatment (such as physiotherapy) does not achieve the desired result, and the patient experiences severe pain and disability. The results of joint replacement surgery are often excellent, and many patients experience significant pain relief. The best long-term outcome is achieved by combining surgery with post-operative physiotherapy, which ensures that the muscles surrounding the joint function properly and that everything is in order for mobility and function.



Conservative treatment for knee osteoarthritis primarily involves physiotherapy, which aims to reduce joint pain, increase joint mobility, stability, and muscle strength surrounding the joint. Physiotherapy often consists of a combination of the following actions:

  • Patient education and advice

  • Exercise therapy

  • Modifying activities to reduce joint stress

  • Weight loss counseling

  • Knee support

  • Pain management techniques

  • Manual therapy to maintain range of motion

  • Encouraging an active, healthy lifestyle

  • Strengthening the lower kinetic chain

  • Improving proprioception, agility, and balance

  • Enhancing physical function

The combination of supervised exercises and a home exercise program has been shown to produce good results. Weight loss is beneficial in all stages of knee osteoarthritis. It is recommended for patients who have symptomatic knee osteoarthritis and a body mass index over 25. The pillars of weight loss include balancing energy intake and expenditure and increasing aerobic exercise or so-called daily physical activity. Strength training can also increase energy expenditure, resulting in weight control as long as this increased energy expenditure is not compensated by increasing energy intake.

To receive an individualized rehabilitation program and advice, I recommend contacting a physiotherapist specialized in lower limb injuries for those suffering from knee osteoarthritis.


Self care

  1. Exercise regularly: Regular exercise can help strengthen the muscles around the knee joint, which can help reduce pain and improve flexibility. Low-impact exercises like walking, cycling, swimming, and yoga are recommended to start with.

  2. Lose weight: Being overweight puts extra pressure on the knee joint, which can make knee osteoarthritis worse. Losing weight can help reduce this pressure and improve symptoms.

  3. Use assistive devices: Assistive devices such as a cane or knee brace can help take pressure off the knee joint and reduce pain.

  4. Apply heat or cold: Applying heat or cold to the affected knee can help reduce pain and inflammation. A heating pad or warm towel can be used for heat therapy, while a cold pack or ice wrapped in a towel can be used for cold therapy.

  5. Take over-the-counter pain medications: Over-the-counter pain medications like nonsteroidal anti-inflammatory drugs (NSAIDs) can help relieve pain and reduce inflammation.

  6. Get enough rest: Resting the knee and avoiding activities that aggravate the condition can help reduce pain and prevent further damage to the joint.

It's important to note that these self-care tips are not a substitute for medical treatment or the advice of a healthcare professional. If you have knee osteoarthritis, it's important to work with your physical therapist to develop a comprehensive treatment plan.

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