In this article we look in depth at the main causes of damage and degeneration of the articular cartilage, and at what to do and what to use for effective protection of this important tissue.
- Articular cartilage: what it is made of
- Articular cartilage: why does it become damaged and degenerate?
- What can be done to protect the articular cartilage?
Articular cartilage: what it is made of
Cartilage is a connective tissue with a firm yet elastic consistency, found on the articular surfaces of the bones, in order to protect them from rubbing and absorb impacts. It also forms the framework of organs such as the larynx and the trachea.
We can identify 3 types of it:
- hyaline cartilage. It is smooth, flexible and bluish-white in colour. It is the type found in the greatest proportion in the human body. It is found, for example, in the ribs, nose, trachea, bronchi, larynx and on all mobile articular surfaces;
- elastic cartilage. It is opaque yellow in colour and is characterised by high elasticity. It is found in the auricles, the Eustachian tubes and the epiglottis;
- fibrous cartilage. It is whitish in colour and is present in the semi-mobile joints, as it is highly resistant to mechanical stress. It is found in the intervertebral discs, the menisci of the knee and the pubic symphysis.
All of them are made up of cells called chondrocytes and of an extracellular matrix composed of elastic and collagen fibres immersed in an amorphous matrix.
Another fundamental aspect to underline is that cartilage contains no blood vessels or nerves. This is a protective feature, since, being a tissue under heavy strain and subject to trauma, the presence of vessels could lead to haemorrhages.
On the other hand, this characteristic makes it harder for nutrients to arrive: they can only reach the chondrocytes by diffusion through the extracellular matrix (a phenomenon closely linked to its permeability).
The articular cartilage, which covers the ends of the bones in a joint, is the hyaline type. 1% of its weight consists of chondrocytes and 99% of a complex extracellular matrix (water, type II collagen, proteoglycans, glycoproteins and noncollagenous proteins).
Articular cartilage: why does it become damaged and degenerate?
But why is this tissue so prone to damage and degeneration?
- The perichondrium is missing. The perichondrium is a membrane of dense connective tissue containing fibroblasts (which produce collagen fibres) and undifferentiated cells that can become chondroblasts and chondrocytes. These features make it essential for the nourishment and repair of cartilage. Its absence at the level of the cartilaginous articular surfaces is a critical point for regeneration.
- It can be repeatedly subject to trauma and strain. Osteoarticular trauma and injuries are very frequent in adolescents and young people, above all as a result of falls and sports injuries. Another important type of strain is body weight: situations of obesity significantly affect the integrity of the articular cartilage.
- The presence of other joint conditions such as osteoarthritis and rheumatoid arthritis. In joints affected by osteoarthritis the water content increases considerably, which leads to breakdown of the matrix and an increase in permeability. As a result, elasticity and load-bearing capacity decrease.
- Physiological ageing. Because it has a low regenerative capacity, as the years go by the articular cartilage tends to thin physiologically, worn down also by the use of the joint. Partial or full-thickness lesions usually occur after the age of 40.
What can be done to protect the articular cartilage?
As we have seen above, the big problem with cartilage tissue is the lack of vascularisation. This peculiarity has faced researchers with a real challenge: finding the right molecules to be able to provide nourishment and stimulate the proliferation of this tissue.
Cartilage in fact has little, if any, capacity for self-repair, owing to the fact that when an injury occurs the chondrocytes are unable to migrate towards the damaged part of the tissue and set the repair process in motion.
This is precisely why it is worth considering external support and research has shown that there are specific nutrients able to support the structure of the cartilage and promote the regeneration processes of the tissue.
What are these elements?
Collagen peptides with a weight below 3KDa
First and foremost, collagen peptides with a weight below 3KDa! Weight is an extremely important discriminating factor, since the bioavailability of “portions of collagen” is significantly greater than that of native collagen. Furthermore, their small size ensures diffusion into the extracellular matrix.
Collagen peptides are useful for supporting cartilage metabolism and stimulating the chondrocytes to produce matrix components1.
In particular, a patented active (FORTIGEL®), based on bioactive collagen peptides below 3 KDa, has been shown to provide positive support for the composition of cartilage tissue, specifically by increasing the density of the proteoglycans. This parameter was assessed with magnetic resonance imaging2-3.
Other studies carried out with the same active (over 12/24 weeks) have shown an improvement in joint pain and stiffness associated with physical exercise4-5.
Chondroitin
Chondroitin is a glycosaminoglycan (GAG) normally bound to proteins to form a proteoglycan. It is one of the essential components that make up the articular cartilage, giving it high resistance to compression.
Its physiological functions are:
- Maintaining the elasticity of the cartilage
- Preventing its degradation
- Attenuating inflammation
Several studies have supported the use of chondroitin sulphate in conditions of cartilage degeneration, above all linked to osteoarthritis6-7.
Glucosamine
Glucosamine is an essential component of articular cartilage and is able to stimulate the synthesis of hyaluronic acid by the chondrocytes.
It has been observed that it may also have a modulating action on pro-inflammatory mediators at joint level8. Several studies underline its particularly positive synergy with chondroitin sulphate9-10.
So, in a supplement specifically designed for the cartilage, these elements must always be present and accompanied by Vitamin C, Manganese, Copper and Selenium in order to best support the formation of collagen, maintain the physiology of the connective tissues and protect the cells from oxidative stress.
In the event of a cartilage injury, which tends to show itself with a dull pain, localised or diffuse, felt in particular during or after movement, it is very important to talk to your doctor and act as soon as possible.
Time is a fundamental factor in being able to properly preserve the tissue from degeneration.
Fortunately, as knowledge advances and the right tools become available, it is possible to intervene and avoid as far as possible, or at least delay, prosthetic implants in old age.
Moreover, according to a recent discovery11 (2019), it seems that human tissue may regenerate on its own through a process similar to that of some animal species by means of a group of small molecules identified as microRNAs. These molecules are able to regulate the expression of certain specific proteins that have been seen to act on the regeneration of some tissues.
In humans, the activity of these “regenerative” microRNAs varies depending on where they are located. It is greater in the ankle area and in the superficial layers of the cartilage tissue. It is lower in the deep layer of the cartilage and in the area of the knees and hips. This could explain why the hip and the knee are the sites most targeted and most subject to degradation in situations of osteoarthritis.
This extraordinary discovery opens the door to new research and the development of new therapies and intervention strategies for the prevention and treatment of degenerative cartilage diseases.