Chondropathia patellae

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Classification according to ICD-10
M22.4 Chondropathia patellae
ICD-10 online (WHO version 2019)

When chondromalacia patella ( "cartilage disease of the knee cap" ), also Peripatelläres pain syndrome called, is a disease of the cartilage back surface of the kneecap . Often there is a softening ( malacia ) of the cartilage, which is why the disease is also known as chondromalacia patellae , especially in English . The term patellofemoral pain syndrome is often used synonymously .

root cause

With a thickness of up to 7 mm, the cartilage on the kneecap is the thickest in the human body. The cartilage is nourished by a flexing process that pushes the synovial fluid in and out of the cartilage. This flexing process can only take place reliably in a very narrow pressure range. If the contact pressure is too high, this process is just as disturbed as if the pressure is too low.

The most important extensor muscle of the knee joint, the M. quadriceps femoris , reacts very sensitively to inactivity or protection of the leg. Within less than two weeks, the central head of this muscle loses much of its strength. The resulting force, which acts on the upper pole of the kneecap, shifts and with it the load distribution in the kneecap sliding bearing. Regardless of the actual disease, any "bad condition" of a knee can lead to damage to the posterior surface of the kneecap. This clinical picture can take on a life of its own and persist even after the first illness has healed. The resulting nutritional disorders lead to a degeneration of the cartilage, the surface becomes rough, the fibers emerge, one speaks of " unmasking the cartilage ".

The cause of a disturbed pressure distribution between the kneecap and the plain bearing are traumatic changes, malformations of the patella or the plain bearing as well as axial or rotational errors in the affected leg.

Symptoms of illness

In lighter cases, walking on the plane does not present any difficulties, pain occurs when the knee is bent and often when walking downhill. The physical examination reveals a so-called patellar displacement pain in addition to the "patella pressure pain" .


The disease sometimes occurs in children or very young people. Girls and women are more likely to be affected. If left untreated, the clinical picture leads to progressive degeneration of the cartilage. At the end there is arthrosis of the kneecap plain bearing.


Patellar sliding bearing

In chondropathia patellae, the movement test shows rubbing noises or a crunch in the plain bearing of the kneecap and often kneecap pressure. The doctor can trigger certain phenomena during the physical examination, all of which demonstrate the irritation of the patella bearing. Irritation effusions or capsule swelling can occur, but are not necessarily present. There is a special positioning of the knee joint for X-rays , in which the sliding bearing between the kneecap and the thigh bone is shown in different functional states, but the informative value is limited with regard to the cartilage damage. On the other hand, the shape of the sliding bearing, i.e. the corresponding joint portions of the femoral patellar joint, can be assessed well. An unfavorable kneecap shape, for example, the so-called patellar dysplasia , leads to a disadvantageous pressure distribution on the cartilage of the posterior surface of the kneecap and thus represents a predisposition for the development of chondropathia patellae. In contrast to X-ray diagnostics, MRI as another imaging method also shows pathological changes in the cartilage itself.

Femoral patellar osteoarthritis

The picture shows a cross-section through the bones of the thigh, the femoral condyles. The kneecap is in the upper area of ​​the picture. The fine structure of the bone, the so-called cancellous bone, is clearly shown.

The layer of cartilage can be seen between the kneecap and the thigh, the fine, gray border between them is the synovial fluid. In the lower part of the picture is the hollow of the knee with the vessels running through it. The joint capsule surrounds the thigh and the kneecap, you can see the fiber structure. The honeycombed, brightly displayed material is body fat.


Cartilage tissue, especially hyaline cartilage, is incapable of regeneration. It is therefore important to avoid cartilage damage as much as possible! Since the chondropathia patellae results from an unfavorable pressure load on the back surface of the kneecap, all possibilities of avoiding pressure on the kneecap must be used in order not to promote the progression of the cartilage damage. In particular, knee flexion over 90 ° or kneeling activities should be avoided because this significantly increases the contact pressure of the back surface of the kneecap on the corresponding plain bearing of the femur . Knee supports press on the kneecap and are therefore not suitable! Certain sports activities that involve bending the knee are not recommended: sports that are often not associated with knee strain (e.g. breaststroke bending movement) should also be considered.

Surgical measures such as splitting the capsular apparatus, tying the quadriceps tendon or surgically relocating the patellar tendon attachment to the head of the tibia can change the relationship between the kneecap and the plain bearing. However, an operative procedure only makes sense if there is an unfavorable positional relationship in the femoropatellar joint.


  • Rüdiger Döhler : The so-called Chondropathia patellae . Wehrmedizinische Monatsschrift 30 (1986), pp. 288-293.
  • Jörg Franke: The importance of the morphology of the femoropatellar joint in the pathogenesis of the femoropatellar pain syndrome . Med. Diss. Univ. Goettingen 1995.
  • Fritz Hefti : Pediatric Orthopedics in Practice . Springer, 1998, ISBN 3-540-61480-X , p. 286 ff.

Individual evidence

  1. a b W. Pschyrembel: Clinical Dictionary. 266th edition. Verlag Walter de Gruyter, 2014, ISBN 978-3-11-033997-0 .