Osteoarthrosis of the knee
Knee arthrosis / gonarthrosis / wear-and-tear of the knee joint
Osteoarthrosis of the knee is a common form of osteoarthrosis. It is commonly known as arthrosis of the knee and specialists also refer to it as gonarthrosis.
Osteoarthrosis of the knee mainly affects people over the age of fifty years.
Description of the condition
A thin layer of cartilage covers all joint surfaces. This acts like a shock absorber and ensures optimum sliding of the individual bone components in the joint. Osteoarthrosis is associated with a deterioration in quality of the cartilage. This causes the joint to move less smoothly and the shocks are not absorbed as effectively. Loss of cartilage can result in chronic knee symptoms.
As the cartilage is gone, bone-to-bone contact can occur in the joint. This is painful and makes the joint less mobile. The body responds by forming osteophytes. This means that abnormal bony growths occur along the edges of the joint. This is the body's repair response to combat the effects of osteoarthrosis. By making the joint wider, this distributes the pressure over a greater surface area.
Cause and origin
The patient is usually over the age of 50 years. The symptoms develop gradually as a result of ageing and wear-and-tear. The quality of the cartilage decreases with increasing age and wear-and-tear occurs. This is a natural process. Almost everyone over the age of 75 years has osteoarthritis in one or more joints.
Osteoarthritis of the knee can also occur at a younger age. For example, the cartilage can become damaged in an accident. Symptoms can also develop as a result of abnormalities within the joint. Injuries to the meniscus, the cruciate ligaments or an abnormal position of the leg can result in osteoarthritis, because the cartilage is strained for an extended period of time.
Signs & symptoms
People with knee osteoarthrosis usually experience pain and stiffness of the knee joint.
Typical symptoms include:
- Painful knee, particularly when moving around.
- Morning stiffness. This means that the symptoms occur mainly in the morning or after an extended period of inactivity. The person needs to "get moving" before the symptoms decrease.
- Crepitations (a cracking sound or sensation in the knee when moving).
- Widening of the knee joint.
- Decreased mobility of the knee movements. Particularly the flexing of the knee (crouching).
- Locking symptoms (the joint locks suddenly when moving).
Not all of the symptoms are present all the time and people can experience periods with a lot of symptoms or few symptoms. The entire joint is usually sensitive/painful. The affected part of the knee can be more painful.
The joint space is narrowed on the X-ray. Any osteophyte formation will also be visible. X-rays will only be made if the physical examination does not provide certainty about the diagnosis, or if the result of the X-ray will determine the treatment.
Wear-and-tear of the cartilage cannot be reversed. Once it's gone, it's gone. It is possible to keep the cartilage as healthy as possible by getting regular doses of gentle exercise. Think of walking or cycling. We will provide an explanation below about why it is important to keep moving.
Cartilage acts like a sponge. When weight is placed on it, it compresses and the waste products are removed. When the pressure is released, the cartilage sucks in nutrients. The sponge action therefore ensures an ideal environment for the cartilage. This explains why complete rest is bad for the cartilage; the sponge effect is not utilised, resulting in reduced circulation of waste products and nutrients.
An exercise programme for the knee, under the supervision of a physiotherapist, can be created to combat the effects of osteoarthrosis. In addition, various techniques can be applied to keep the knee as mobile and pain-free as possible.
If conservative treatment does not result in improvement, then surgical intervention can be considered. A number of procedures are possible. A knee replacement (knee prosthesis) can be performed for severe, increasing symptoms. Surgeons are reluctant towards joint replacements in patients younger than 50 years, because the risk is then higher that another knee replacement will be required at a later stage.
Nugteren, K. van & Winkel, D. (2007). Onderzoek en behandeling van de heup. Houten: Bohn Stafleu van Loghum.
Nugteren, K. van & Winkel, D. (2009). Onderzoek en behandeling van artrose en artritis. Houten: Bohn Stafleu van Loghum.
Verhaar, J.A.N. & Linden, A.J. van der (2003). Orthopedie. Houten: Bohn Stafleu van Loghum.