Knee cartilage: what is it and why is it important?

Knee cartilage is a specialized connective tissue : it is made up of collagen, water, chondrocytes and proteoglycans, cells that are also responsible for the production of important enzymes, above all elastase and hyaluronidase, which are very important as they promote the degradation of damaged collagen .

The cartilage of the knee, but it is a matter that can be extended to all the cartilages of our body, has no vessels, is not innervated and is very elastic and resistant. In the specific case of that of the knee, it is resistant to traction and pressure.

The main problem of cartilaginous tissue is that it is scarcely capable of regenerating itself , a question which is connected to the appearance of most of the questions concerning the pathologies and problems of the tissue in question.

The most common pathologies affecting the knee cartilage

The pathologies that most commonly affect the knee cartilage are osteoarthritis and chondromalacia, respectively.

Osteoarthritis occurs when the cartilage tissue in the joint gradually shrinks and then disappears. The cartilage that once made it easy for the bones to move against each other is being replaced by a less elastic, less smooth and generally less supportive surface for the joint. Osteoarthritis therefore causes problems with every joint movement.

Osteoarthritis is typical of middle and old age, with risk factors such as obesity and trauma that can anticipate its appearance.

Chondromalacia is, on the other hand, a degenerative disease that attacks the cartilage of the knee. It is typically caused by sprain trauma or even by injuries caused by overloading. It presents with significant joint pain and possible stiffening of the joint.

However, these are not the only problems that can affect the knee cartilage. As we were able to say just before, cartilage has a poor regenerative capacity, and for this reason a tissue injury has particularly serious and above all long-term consequences.

The lesion of the cartilage: general characteristics

Cartilage can be subject to lesions, which tend to be caused by the concomitance of trauma and degenerative processes.

Furthermore, when there is a degenerative process in progress, the cartilage ends up, over time, by losing its elasticity and its ability to support. Over time, inevitably, the cartilage ends up disappearing, leaving the bones that were covered with it bare, in friction on each other.

Chondral lesion and osteochondral lesion

It is also worth remembering that when the lesion affects only the cartilage we have what in medical jargon is called a chondral lesion . In the event that the underlying bone should also be affected, we can speak of an osteochondral lesion.

Knee cartilage injury: the most common signs and symptoms

There are several symptoms that are related to cartilage injuries . Pain is a constant, even if it is rarely proportional to the extent of the lesion: there are very common cases of minimal lesions that give rise to very intense pain and of lesions and degeneration that are instead extensive and cause more than limited pain.

However, pain is not the only possible sign of knee cartilage injury. It is possible to experience swelling, movement limitations even if not accompanied by pain and stiffening of the joint.

Diagnosis: how to identify a knee cartilage lesion

A superficial observation of the joint is not sufficient to identify the presence of a lesion to the knee cartilage.

It is typically used to:

• Nuclear magnetic resonance , using a contrast medium, a technique that is useful for identifying both types of lesion;
• Nuclear magnetic resonance , without resorting to a contrast medium, a technique which however is less and less used as it is not able to identify superficial lesions;
• TAC , which is used when it is necessary to study the condition not only of the cartilage, but also of the ligaments and menisci.

Ultrasonography is never used, as this diagnostic technique is unable to identify any minor injuries.

With regard to chondrial lesions, i.e. those that exclusively affect the cartilage, without also attacking the bones, we proceed with arthroscopy .

Possible therapies for knee cartilage injury

We are facing a relatively important problem, as it is very difficult to intervene for reconstructive purposes. The bulk of interventions and therapies aim to interrupt the degeneration of the tissue and therefore to stabilize the situation.

You can intervene both surgically and instead by ways that do not require surgery.

It is preferable to proceed without surgery when the lesion is either small or affects the ends of the tissue. Non-surgical therapy is often preferred even for small lesions.

For symptomatic purposes, we intervene with the administration of NSAIDs, non-steroidal anti-inflammatory drugs, in different dosages and combinations.

It also intervenes with viscosupplementation, or with infiltrations of hyaluronic acid. Typically you can also decide to aspirate any liquids from the inflamed knee before proceeding with infiltrations.

When surgery is preferred: here are the therapies

It is also possible to proceed surgically, using different methods of intervention:

1. Microfractures : an outdated technique which involves drilling the bone on the articular surface not covered by cartilage; the damage stimulates the creation of fibro-cartilaginous tissue, which however does not have the same elasticity as the original cartilage;
2. Plastic Mosaic : that is, with the removal of part of the bone with cartilaginous tissue to be implanted in the areas that have remained uncovered;
3. Chondroplasty : technique that can offer more than interesting results, which however require relatively long physiotherapy courses, which are necessary to fix the tissue being transplanted;
4. Autologous chondrocyte transplantation : fragments of cartilage are taken and used in the laboratory to isolate the chondrocytes. Subsequently these chondrocytes are implanted on the injured cartilage, for regenerative purposes.

Recovery times

Establish in advance what the recovery times are from an injury to the knee cartilage as it depends a lot on the pathology that has been suffered. Certainly, after surgery, a period of rehabilitation of the joint will follow, the duration of which will depend on the patient’s ability to respond.

I have written several guides on the knee joint and the possible problems associated with it that I invite you to read:

• Knee effusion
• Knee pain 
• Inner knee pain
• Pain behind the knee
• Fluid in the knee
• Baker’s cyst
• Fissure of the meniscus