What is osteoarthritis?
Osteoarthritis of the knee is a slowly progressive, not primarily inflammatory degenerative disease (osteoarthritis) of the knee joint. Joint wear and tear occurs when the cartilage that acts as a buffer between the bones breaks down, leading to pain in the joint structures. Pain is usually felt when bending the knee, when climbing stairs and also after long periods sitting or lying down. Pain in the morning is a common complaint in the early stages of knee joint osteoarthritis. The joints feel stiff. The pain usually subsides after the joint has been able to warm up. A worn joint can easily become inflamed. Osteoarthritis that was initially non-inflammatory therefore becomes activated osteoarthritis with inflammatory phases. The aim is to keep the inflammatory phases as brief as possible by using medication.
Types of knee osteoarthritis
Three bones come together in the knee joint:
- The thigh bone (femur)
- The kneecap (patella)
- The shinbone (tibia)
Joint wear and tear always occurs between the colliding bone surfaces, each of which is covered with a smooth layer of cartilage. The joint between the thigh bone and the shinbone consists of two joint sections: the inner (medial) and outer (lateral) parts. This is why physicians speak of different compartments in the knee.
- Medial knee osteoarthritis: If the inner part of the knee joint is affected by wear and tear, this is medial osteoarthritis.
- Lateral knee osteoarthritis: If the knee osteoarthritis is located in the outer area of the knee, this is lateral osteoarthritis..
Osteoarthritis is the most common joint disease in adults worldwide. In Germany, knee ais is the most common, followed by hip joint osteoarthritis.1,2 Age is a strong risk factor in the development of osteoarthritis. More than half of women and a third of men aged 60 are affected – and these figures are increasing1.
Causes of knee osteoarthritis
There is often no clear or concrete cause for knee joint arthrosis: In most cases, it is “primary osteoarthritis” – caused by age-related degradation of the cartilage. In addition, congenital misalignments (bow-legged or knocked-kneed) and certain illnesses or injuries can result in joint wear and tear. These are referred to as “secondary osteoarthritis”.
Symptoms and signs of knee osteoarthritis
Typical signs of osteoarthritis in the knee joint are:
- Knee pain when climbing stairs and when walking on uneven ground.
- Pain is particularly bad when starting to move after long periods of rest and then slowly subsides only to recur after prolonged periods of stress.
- Symptoms increase after carrying heavy loads.
- In the course, there may be a noticeable swelling.
- In the advanced stages, crunching and crackling noises can be heard when the knee is moved.
- The joint is particularly sensitive in damp and cold weather conditions.
The more advanced the osteoarthritis, the more pronounced the symptoms: The pain becomes more frequent and often occurs even when at rest. Knee mobility continues to decrease1.
Osteoarthritis stages: grades of joint wear and tear
There are four grades of severity for osteoarthritis, depending on the degree of wear to the knee joint:
Osteoarthritis Grade I
The cartilage layer in the knee is undamaged, but soft. The person is still largely symptom-free, and the function of the joint is not yet impaired.
Osteoarthritis Grade II
The first damage to the cartilaginous cell structure may have occurred, and the cartilage surface is roughened up. There are usually not any symptoms or functional impairments of the knee joint in the early stages of knee osteoarthritis.
Arthrosis Grade III
The cartilage surfaces are damaged. The first cracks form. The person suffers from joint pain as the cartilage layer has worn away.
Arthrosis Grade IV
Total cartilage loss: The now exposed bone surfaces rub against each other. This is known by experts as Chondromalacia grade 4. Abrasion in the knee joint causes stiffening and painful inflammation, swelling and joint effusion.
Risk factors for osteoarthritis
Knee injuries, particularly of the menisci and ligaments, can cause natural wear to start earlier or speed up the degeneration process. The rupture of the anterior cruciate ligament (ACL) is one of the most common knee injuries. A consequence of this injury is often instability of the knee joint, which in the long term can lead to increased wear of the cartilage (cartilage degeneration) – and thus to the development of osteoarthritis3.
Exercise is essential for the nutrition of the cartilage: As the cartilaginous layers are not supplied with blood, metabolic products and nutrients can only be absorbed by movement.
For example, those with bow-leggedness, knock-knees, leg length discrepancies and cartilage weakness may be more prone to osteoarthritis.
Being overweight is one of the most significant risk factors for developing gonarthrosis. It usually accelerates the degeneration process.
Signs of wear can be more pronounced in highly physical professions, for example, tilers or construction workers.
Competitive athletes are subject to high levels of pressure, thereby significantly increasing the related cartilage wear and tear.
Changes to the cartilage metabolism also worsen nutrient supply to the cartilage.
How can I prevent osteoarthritis?
Years of being overweight can damage a person’s joints. This significantly increases the risk of developing osteoarthritis. This is because: The knee joints must bear large loads, which means they wear out more quickly. Being overweight starts with a BMI (body mass index) of 25. A BMI of over 30 is when someone is classified as being severely overweight or obese. People with osteoarthritis are therefore often advised to lose weight.
Self-management – how to improve your quality of life
With self-management, osteoarthrtis patients can do a great deal to reduce pain and improve treatment outcomes: Be active in dealing with the disease. For example, eat a healthy diet, lose weight sustainably and take regular physical activity.
Nutrition for osteoarthritis
Nutrition plays a significant role in the development of arthrosis. Nutritional changes cannot cure athrosis but can have beneficial effects. That is why the scientific focus is on the connection between arthrosis and nutrition.
Pay attention to your diet and weight: Study on weight and osteoarthritis
An Australian study examined the connection between being overweight and developing osteoarthritis of the knee. Patients of a healthy weight only developed osteoarthritis at an older age. Young, healthy but overweight patients saw a decrease in the cartilage at a younger age1.
Sport and exercise with osteoarthritis
What really helps? Does exercise help or is it better to rest? One thing is for sure: Sport and exercise are invaluable both for those already with gonarthrosis and those looking to prevent it! When in pain, people often prefer to rest and try to move the knee as little as possible. This is precisely the wrong thing to do. Lack of exercise is one of the main risk factors for arthrosis.
Infographic: Sport and exercise with osteoarthritis
Find out how good movement and sports are for osteoarthritis.
Targeted training of the arthrotic joints strengthens the muscles and improves coordination. Movement produces more synovial fluid, which leads to less abrasion.
Which sports are suitable for those with osteoarthritis?
Beneficial sports with gentle movements
- Aqua aerobics
- Cross-country skiing
Unsuitable “contact” sports
- Alpine skiing
Find the sporting activity you like best. Avoid sports-related strain. If you are unsure of whether you can do a specific sport, ask your doctor for advice.
Therapeutic measures – what helps in osteoarthritis?
Although osteoathritis is incurable, numerous treatment options can relieve pain and make everyday life easier.
- Orthopaedic aid (such as insoles, supports, orthoses)
- Physio or exercise therapy
- Physical therapy (e.g. magnetic field therapy, ultrasound, electrical stimulation, shockwave)
- Occupational therapy
- Naturopathy (e.g. acupuncture, aqua aerobics)
- Medication (painkillers, anti-inflammatory drugs)
Six home exercises
Exercises that can be performed without pain can counteract the progression of the ostearthritis. The examples listed here are not just beneficial for the knee. They support the entire musculoskeletal system and keep you fit.
A rarely used therapy for knee osteoarthritis is arthroscopy, in which a small camera (endoscope) is inserted into the knee joint to obtain a clear picture of the interior of the joint and to decide on suitable therapy measures.
In osteotomy, a wedge of bone is removed or inserted to correct misalignments or arthrotic damage on one side of the knee joint. By correcting the leg axis, the affected cartilage is relieved, thus preventing increased wear.
Partial joint replacement
If only one side of the knee joint is affected by osteoarthritis, there is the possibility of surgery. In a partial joint replacement surgery, only the destroyed or affected side of the knee joint is replaced with metallic or plastic components. This operation is also known as an unicompartmental knee joint replacement. The healthy side is preserved.
Complete joint replacement (full knee prosthesis)
This operation is only considered if both sides of the knee surface have been significantly destroyed and the patient is in so much pain that they cannot be helped by other therapies. During the operation, the destroyed surface of the knee joint is replaced by metallic and plastic components. These are shaped to best match the anatomy of the knee joint.
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1 Arthrose. Gesundheitsberichterstattung des Bundes; Heft 54. Herausgeber: Robert Koch-Institut, Berlin 2013. Published online at: www.rki.de/DE/Content/Gesundheitsmonitoring/Gesundheitsberichterstattung/GBEDownloadsT/arthrose.pdf (Last accessed: 27.02.2018).
2 Fuchs J. et al. Prävalenz ausgewählter muskuloskelettaler Erkrankungen. Ergebnisse der Studie zur Gesundheit Erwachsener in Deutschland (DEGS1). 2013;56(5-6):678–686.
3 Paschos NK. Anterior cruciate ligament reconstruction and knee osteoarthritis. World J Orthop. 2017;8(3):212–217.
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