Chondromalacia (ICD code: M94.2) refers to the breakdown and softening or fraying of the joint cartilage. Chondro stands for cartilage and malacia for softening. According to the definition, the disease is classified as a chondopathy, i.e. a cartilage disease.
Articular cartilage plays a decisive role in the functionality of the joints; it covers the articular surfaces of all real joints. On the one hand, the cartilage ensures a smooth surface of the joint surfaces and thus enables low-friction mobility. It also acts as a shock absorber and cushions joint movements.
The thickness of the cartilage varies depending on the joint and is between 0.5 mm in the small joints of the fingers and 5 mm in the knee joint. However, excessive joint loads and acute injuries can damage the cartilage substance. This impairs joint function and leads to limited mobility and pain.

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In chondromalacia, the cartilage layer on the bones is softer than normal. The softening can occur in various degrees of severity and can progress to complete loss of the cartilage tissue.
What are the different degrees of cartilage damage?
Depending on the extent of the cartilage damage (chondropathy), a classification is made. It is divided into grades 0 to 4 according to Outerbridge, who first described it. The decisive criterion is the depth of the cartilage damage.
- In grade 0 chondropathy, the cartilage tissue is completely intact and healthy. There is no damage and therefore no impairment of joint function.
- Grade 1 chondropathy is accompanied by softening of the cartilage in places. The cartilage substance is still completely present and smooth. Softened areas are found in particular in areas that are exposed to intense pressure.
- Roughened cartilage with small cracks, on the other hand, is seen in grade 2 chondropathy.
- In grade 3 , the cracks extend to the bone, leaving bone substance partially exposed.
- In grade 4 chondropathy, the cartilage layer is completely destroyed and the bone is completely exposed. This means that the joint can no longer function normally and corresponding symptoms occur.
There is also a newer classification according to ICRS criteria. ICRS stands for International Cartilage Research Society, a society that specializes in cartilage diseases. In many areas, this classification corresponds to Outerbridge's classification , although the extent and depth of the lesion are described in more detail.
- ICRS grade 0: No recognizable defects
- ICRS grade 1
- 1A: intact surface, slight softening
- 1B: additional superficial cracks
- ICRS grade 2: lesion depth < 50% of the cartilage thickness
- ICRS grade 3: lesion depth > 50% of cartilage thickness, bone not yet exposed
- ICRS grade 4: lesion extends to the bone
Chondromalacia is usually due to overloading of the joint in question. Sporting or occupational activities can stress the joint and damage the cartilage substance. In particular, sports with a high and also one-sided joint load as well as sports that require extreme ranges of motion of the joints are considered a risk factor for chondromalacia. These include tennis and soccer, for example. Runners also often suffer damage to the cartilage in the hip or knee joint area. In the case of lesions in the area of the hip joint, micro-lesions, i.e. minute damage and tears caused by the constant repetitive movement of the hip during running, are frequently observed.
However, genetic factors also appear to play a role in the development of chondromalacia. The cartilage tissue can be more or less resilient due to genetic factors.
Traumatic events, i.e. an accident or a fall, are also among the causes of cartilage softening. Sudden and hard impact or rotational movement of the joint can lead to tears in the cartilage tissue. In the case of bone fractures , direct damage to the cartilage, known as cartilage contusion, is also possible. However, this is always a serious grade 4 injury.
Finally, inflammation and chronic joint effusions can also lead to a softening of the cartilage tissue and make it more susceptible to injury.
The symptoms depend primarily on how badly and where exactly the cartilage is damaged. Articular cartilage has neither blood vessels nor nerve fibers. The cartilage damage itself therefore does not cause any pain. The pain is caused by irritation of the bone and bone marrow.
In the early stages, chondromalacia usually goes unnoticed. Some patients merely experience an unpleasant feeling of pressure on the affected joints. As the damage progresses, however, the pain increases, especially during movement. Later, those affected suffer not only from pain during movement, but also at rest. Pressure on the affected joint or, in the case of the knee, on the kneecap also triggers pain, and a joint effusion may develop, which is characterized by significant swelling.
If cartilage softening is suspected based on the symptoms, the affected joint is examined first. A joint effusion, redness or swelling of the skin over the joint can provide initial indications of cartilage disease when the joint is examined externally (inspection). Careful palpation of the joint in a resting position is also one of the first diagnostic measures.
This is followed by an examination under load, whereby the joint is moved passively and rotated slowly. Passive means that the patient does not move the joint themselves, but all movements are carried out by the examining doctors. This is the only way to detect the typical pain of chondromalacia. Depending on the extent of the cartilage damage, so-called crepitations can also be felt during joint movements. This is a crackling noise caused by the direct friction of bone on bone in grade 4 chondromalacia.
Following the inspection and physical examination, an ultrasound examination of the joint is usually carried out. Both joint effusion and the joint surfaces can be visualized here. In some cases, an X-ray examination will also be necessary. This is particularly necessary after an accident in order to determine or rule out a bone fracture. In addition, chondromalacia also shows a thickening of the bone tissue under the joint cartilage.
More precise conclusions can be drawn with the help of tomographic imaging, in particular computer tomography or magnetic resonance imaging(CT and MRI). Here, both the bone and the joint surfaces can be assessed.
What happens during arthroscopy?
However, direct observation of the joint cartilage is only possible duringarthroscopy. An optical probe with a video camera at the tip is inserted into the joint through a small incision. This small camera enables a precise inspection of the joint and the cartilage. With additional instruments inserted during arthroscopy, dead cartilage can also be removed and the joint surface smoothed. The depth of the cartilage damage can also be precisely determined.
Arthroscopy is an invasive diagnostic procedure that is only possible under anesthesia (usually general anesthesia, rarely spinal anesthesia). It should therefore only be carried out if there is an appropriate indication. One possible indication would be, for example, the planning of an artificial joint prosthesis, which is often indicated by an arthroscopy in advance and the patient is informed of the prospects of success.
In some cases, however, the bone or cartilage can also be cleaned and smoothed during arthroscopy so that an artificial prosthesis is no longer or not yet necessary. Among other things, medication can also be injected into the joint to rebuild the cartilage tissue or prevent softening from progressing.
Arthroscopy is therefore both a diagnostic measure and a therapy.

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Conservative acute treatment should be started immediately after diagnosis. The load on the diseased joint should be reduced and is absolutely necessary to protect the cartilage tissue. Cold or heat treatments and local applications with anti-inflammatory and pain-relieving creams or ointments can also alleviate the symptoms.
Once the symptoms have subsided, physiotherapy treatment can help you return to an active and pain-free life. This is usually possible on an outpatient basis and close to home, but sometimes this treatment is also carried out on an inpatient basis in a specialized rehabilitation clinic.
Bone fractures often require immobilization in plaster or surgical treatment. Surgery may also be advisable even if there is no bony injury. This is particularly the case if the symptoms do not improve despite consistent conservative treatment and the pain does not significantly decrease or disappear. In these cases, where conservative therapy fails, there is usually significant cartilage damage. This can only be effectively repaired by surgery. Various types of cartilage therapy are available for this purpose. For example, the regenerative capacity of the cartilage can be improved by drilling holes(microfracturing) and healthy cartilage tissue can grow in via these drill channels.
Larger cartilage defects with exposed bone areas, on the other hand, often require so-called abrasion arthroplasty. In this procedure, the damaged cartilage is exposed and milled away using arthroscopy . This allows stem cells from the bone marrow to enter the wound, which ideally form new cartilage.
The joint is then cleaned of the removed cartilage and bone material as part of the so-called joint toilet using an irrigation fluid. However, it usually takes several weeks, sometimes even several months, for new cartilage tissue to form. Patients should therefore relieve the affected joint in the initial period after the operation, for example by using crutches.
In most cases, steady, pain-adapted weight-bearing on the joint is possible after 2 weeks. Prolonged immobilization of the joint should be avoided, as this can lead to shrinkage of the joint capsule and subsequent stiffening of the joint. This applies in particular to the shoulder joint, which is at risk of stiffening after just a few days of immobilization. Appropriate physiotherapeutic measures are therefore particularly important after surgery and help to ensure that the joint functions well again.