Synonyms
Gonarthrosis, knee joint arthrosis, knee arthrosis
Definition
Osteoarthritis of the knee is an irreversible, progressive destruction of the knee joint, usually as a result of a permanent imbalance between load and capacity.
Introduction
At the age of 75, about 60-90% of people have osteoarthritis in one or more joints. Knee arthrosis is less common than, for example, arthrosis in the fingers. Since the knee is a central joint that is always loaded with the entire body weight, the patients’ suffering is relatively more pronounced in this area, and there are greater restrictions on quality of life than in smaller joints.
The bony knee joint consists of three bones: These can all be affected together (pangon arthrosis) or individually by arthrotic changes. One of the most common forms of arthrosis is that between the femur and the patella (femoropatellar arthrosis = patella arthrosis). – Thigh bone (femur)
- Lower leg bone (tibia) and
- Kneecap (patella).
Symptoms
Often the arthrosis in the knee remains silent during the first years. This means that changes in the joint are already visible on the X-ray, but the person affected has no symptoms. Initially, patients describe their complaints as stiffness and extensive joint pain and muscle aches.
Within an activated arthrosis, the knee can swell and appear overheated. The increased pressure in the knee joint can also lead to the development of a popliteal cyst. The mobility of the knee is more restricted in this case due to pain, which improves again after the irritation has subsided (e.g. hiking break of several days).
Particularly in the morning, after getting up and after sitting for a long time, a pain develops in the further course of the disease, which disappears after a few minutes of movement. Some patients experience more severe symptoms in damp or cold weather. After several years of the disease, deformations of the joints, malpositions and fatigue pain may occur.
Without therapy, patients with osteoarthritis of the knee may be so limited in their ability to walk that they have to use crutches or a wheelchair/rollator. However, an almost symptom-free course is also possible. As is usually the case in life, the individual course lies somewhere in between.
Causes
Primary and secondary arthrosis can be distinguished according to their causes. While the cause remains unknown in primary arthrosis, secondary arthrosis is preceded by another disease or trauma/accident of the knee. Specific causes of secondary osteoarthritis of the knee are long-standing malalignments such as knock-knees (genu valgum) or bow legs (genu varum).
There is a disproportion between the load and the load capacity of the middle or outer joint space, resulting in one-sided wear and tear of the joint cartilage. Further causes are previous injuries in the knee joint gap, such as fractures/ fractures of the thigh or lower leg bone with gap formation in the joint, as well as meniscus injuries. If unevenness remains on the joint surfaces after injuries in the knee, there is increased wear and tear of the cartilage on the opposite sides, up to and including bone baldness.
Frequent carrying of heavy objects (mostly at work) contributes to increased pressure in the knee joint, so that degenerative changes in the cartilage surfaces occur more quickly. Working in a kneeling position, such as tiling, also places enormous strain on the knee. As a result, under certain conditions, arthrosis in the knee has been recognised as an occupational disease since 2009.
