Arthrosis stages

Types of arthrosis stages

There are different classifications according to which the stages of arthrosis are classified. According to the X-ray image, the different stages are classified according to Kellgren and Lawrence. The cartilage damage is classified according to Outerbridge.

The different stages of arthrosis

A progressing arthrosis is divided into a total of three arthrosis stages. Arthrosis stage 1 is defined as an arthrosis that does not cause any symptoms and is usually not noticed by the patient. It is also called silent arthrosis.

The surface of the cartilage is still intact and smooth. However, there is a softening of the cartilage. As a rule, stage 1 arthrosis is seen as a chance finding.

For example, patients come to their doctor with an X-ray of a joint because they fear a fracture in the course of an accident. Characteristic changes in the X-ray image indicate an arthrotic process. It can be assumed that most people who have passed the age of 60 suffer from at least one, but probably several, arthroses, the cause of which is usually years of incorrect strain.

In arthrosis stage 2, all arthroses are classified in which an inflammatory process is already in progress and usually already causes symptoms, i.e. leads the patient to the doctor. It is often the case that arthrosis first starts in stage 1 and then moves on to stage 2. It varies from patient to patient how long the arthrosis remains in stage 1 and when it passes to stage 2.

Arthroses of stage 1 show the typical painful clinic. However, the pain is not permanent and can sometimes be controlled without medication. Arthroses of stage 3 are also called manifest arthroses, which are active, trigger a medium to strong inflammatory reaction and exist for a long period of time.

All stage 2 arthrosis changes over time to stage 3 if left untreated. Due to the severity of the symptoms, intensive medical and physical treatment of the patient is necessary. In addition to the pain, which is usually permanent, there are also restrictions of movement and reduced function of the affected joints. and surgery for arthrosis


A common classification of the arthrosis stages, which is especially used in the area of knee joint arthrosis, is the Outerbridge classification I -IV. In stage I, the surface of the cartilage still appears preserved and smooth. However, there is a softening of the cartilage.

During arthroscopy, the softening can be tested with the aid of an instrument (palpation hook). If too much pressure is applied with a tactile hook, damage can occur (more quickly than with healthy cartilage). The changed cartilage is therefore more susceptible to further injuries.

In addition, blisters may already be present. In the second stage the surface of the cartilage is changed. The cartilage appears frayed and rough.

Smaller cracks may also be present. However, this damage is limited to a maximum of half the total thickness of the cartilage. The depth of a crack can be estimated with the palpation hook and may expand further over time.

The cartilage shows clear damage and tears. This damage now affects more than half of the thickness of the cartilage layer. However, the underlying bone (subchondral bone) is not visible.

Tears with such a depth can be the result of trauma. Surgical treatment is usually well possible if the defects are not narrow. There may also be wide depressions that can lead to cartilage baldness.

These defects are more difficult to treat surgically. You can find more information about surgery for osteoarthritis here. At this stage, the entire cartilage layer is also affected.

In addition, the underlying bone is revealed. An area in which the cartilage is worn down to the bone is also called cartilage baldness. If there is further stress and wear, the bone can also be affected.

Deformations are the result. This process is usually accompanied by severe pain. The arthrotic wear and tear in the knee joint develops over many years.

At the beginning, hardly any complaints are noticed, until finally, after many years, every strain on the joint leads to pain symptoms. This is why arthrosis is often only discovered in more advanced stages. However, the earlier the diagnosis of knee arthrosis is made, the earlier therapy can begin and the wear and tear process can be stopped.

In the early stages of knee arthrosis, it is initially (usually small) cartilage damage that is responsible for changes in the knee joint. On some sections of the joint, an additional load is created and the cartilage and, in the long term, the underlying bone is affected. The duration and extent of the so-called intermediate stage of osteoarthritis in the knee depends on the extent to which the knee joint is strained by body weight, rotational movements or sports involving rapid acceleration and changes of direction.

The cartilage is gradually worn away and the pressure on the underlying bone increases. In order to distribute the pressure better, the joint surface is enlarged and bony extensions (osteophytes) are formed. In osteoarthritis of the knee, these excrescences are sometimes palpable or even visible.

The cartilage damage spreads more and more, the joint space narrows and thus the knee joint becomes more and more immobile. In the late stage of knee joint arthrosis, the cartilage is degraded and the thigh and lower leg bones lie directly on top of each other. The X-ray image shows compression and hardening of the bone (subchondral sclerosis). When the joint space has completely disappeared, the affected knee joint is stiff.