Cartilage serves as a natural shock absorber in the joints. As an elastic protective layer of the joints, they can be several millimetres thick. They cushion loads and prevent bones from colliding directly with each other. In the case of cartilage damage, the cartilage is damaged. This becomes noticeable with pain during movement. Such cartilage damage can have various causes.
What is cartilage?
Cartilage layers are located on the joint-forming bones and can be several millimetres thick. They prevent the bones from colliding directly with each other during movement. Cartilage is elastic, shock-absorbing and low-friction tissue that consists of 80 percent water. There are no blood vessels or nerves in cartilage tissue. The cartilage therefore has no blood supply of its own and is supplied with nutrients via the synovial fluid and the bones beneath it. The cartilage’s ability to regenerate is therefore limited. With increasing age and constant strain, the cartilage becomes brittle, which eventually leads to cartilage damage.
Types of cartilage
A distinction is made between hyaline, elastic and fibrous cart ilage. Hyaline and elastic cartilage are surrounded by a cartilage membrane (perichondrium). This cartilage membrane is absent in fibrocartilage. It consists of an inner cellular layer, in which precursor cells are located, and an outer connective tissue layer. Blood and lymph vessels that nourish the cartilage end in the outer layer.
Hyaline cartilage is also known as vitreous cartilage and is characterized by high compressive elasticity. It is present where pressure loads mainly occur. It is found on most joint surfaces, but as articular cartilage it has no cartilage membrane. In adults, hyaline cartilage is the most common type of cartilage. Hyaline cartilage is also present on the ribs and in the laryngeal framework. Hyaline cartilage can calcify.
Elastic cartilage is cell-rich cartilage tissue that is highly elastic in compression and bending. Its structure is similar to hyaline cartilage, but it is even richer in fibers. Elastic cartilage is found in the epiglottis and in the auricles.
Fibrocartilage is also known as connective tissue cartilage and contains only a few cells. It is rich in collagen fibers and is found in the human body wherever shear forces occur. It has a high tensile strength. Fibrocartilage is found in the menisci of the knee joint, in the joint labrum and in the intervertebral discs.
Effect of the cartilage
Articular cartilage is important for joint movement and enables the joint surfaces to glide smoothly. When viewed under a microscope, the smooth surface of the articular cartilage shows small dents like a golf ball. The synovial fluid serves as a lubricating layer and adheres to the surface of the cartilage. Under load, water is pressed out of the cartilage to reduce the sliding resistance. Cartilage fluid nourishes the cartilage cells. Like a sponge, it is pressed out of the cartilage under load and flows back into the cartilage when the load is removed.
The cartilage can be deformed under pressure like a water cushion. Impacts on the joint are absorbed, cushioned and distributed over a larger surface area. The shock-absorbing effect of the cartilage is reinforced by the synovial fluid. The cartilage returns to its original shape when the load is removed.
Symptoms of cartilage damage
Cartilage damage can remain symptom-free for a long time or only become noticeable with minor symptoms. They are therefore often only discovered by chance. It is not always possible for patients to recognize cartilage damage themselves. Cartilage damage often only becomes noticeable when it is already more advanced. The microscopic cartilage abrasion caused by chronic processes leads to inflammation of the mucous membrane that lies on the inside of the joint capsule. With increased irritation, the mucous membrane produces joint fluid and thus a joint effusion. As the joint cartilage has no nerve endings, the inflamed joint capsule is usually responsible for the pain that occurs.
Typical symptoms, especially in the knee, are:
- Swelling of the affected joints
- Pain when the joint is stressed, such as during sport or climbing stairs
- Restriction of movement
- vague feeling of pressure on the affected joints
- Rubbing and cracking of the joints
- as the disease progresses, pain also occurs at rest
Severity of cartilage damage
There are four degrees of severity for cartilage damage:
Severity 1: Cartilage is still smooth and completely present, but is softened in places
Severity 2: Cartilage is roughened and has small cracks in places
Severity 3: Cartilage shows cracks and holes that do not yet reach the bone
Severity 4: Cartilage layer is completely destroyed in places, leaving the underlying bone exposed
Causes of cartilage damage
The cartilage structure loses its elasticity with advancing age and excessive strain. The shock-absorbing effect decreases as the water content in the cartilage decreases. Over time, the cartilage becomes brittle and cracks. If the cartilage, which is no longer completely smooth, rubs against its counterpart, defects can occur when small particles become detached. If the cartilage layer wears away completely, the ends of the bones rub against each other during movement. Arthrosis develops.
Cartilage damage can also have other causes:
- Accidental cartilage tears (=flake fracture) due to sports injuries or accidents at work
- Malposition or deformity (dysplasia) of the affected joint
- Inflammation of the affected joint due to bacterial infection or rheumatoid disease
- Circulatory disorders
- Lack of exercise
- Overweight
- genetic factors, if less resilient cartilage tissue is present due to hereditary factors.
There is an increased risk of cartilage damage in sports with a high one-sided joint load or work with a high weight load.
How is cartilage damage diagnosed?
If you have symptoms of cartilage damage, the doctor will discuss your medical history with you. He will ask you what the symptoms are and when they occur. During a physical examination, he will check the mobility of the joint and how it reacts to pressure. He will perform an X-ray examination of the affected joint to rule out osteoarthritis. In the early stages, no cartilage damage is visible on the X-ray images. Magnetic resonance imaging (MRI) is used for further diagnosis. Surgical assessment of the affected joint (arthroscopy) allows precise diagnosis of cartilage damage and further therapeutic measures, such as the removal of affected cartilage tissue, regenerative or reparative therapy measures.
Treatment of cartilage damage
Cartilage damage can be treated conservatively and surgically. Painkillers and anti-inflammatory drugs such as ibuprofen, paracetamol and diclofenac can be taken for acute pain. Their anti-inflammatory effect is also intended to combat the irritation of the joint mucosa. Due to possible side effects, painkillers should only be taken for a limited period of time. If the cause is an underlying disease, causal treatment is carried out. Weight reduction is strongly recommended for overweight people, as the knee joint bears approximately 5 times the body weight with every step. Exercise helps to build muscle and protects the cartilage.
Infiltration treatments with hyaluronic acid have an anti-inflammatory effect and improve the gliding ability of the damaged cartilage. Infiltrations of autologous plasma use the body’s own growth factors to induce new growth of cartilage matrix.
How can physiotherapy help with cartilage damage?
Physiotherapy is used to strengthen the muscles. It improves the mobility and stability of the joints. Incorrect loading and misalignment of the joints can be corrected with various exercises. If there is significant joint effusion, lymphatic drainage helps to reduce swelling. Pain can be alleviated as inflammatory messengers are broken down more quickly. The effect of physiotherapy can be supported by applying heat. If the inflammation is acute, a cold pack can help.
How can surgery help?
Surgery should be the last step in the treatment of cartilage damage if the disease cannot be treated conventionally. Surgical treatment options include cartilage smoothing, bone marrow stimulation or the implantation of cartilage cells and cartilage tissue. These operations are performed in a minimally invasive manner as part of an arthroscopy. Bone marrow stimulation surgery is used if the cartilage damage is less than 2 cm in size. The defect is drilled into in order to fill the defect with cartilage regeneration tissue from the emerging bone marrow. For larger defects, different forms of cartilage cell transplantation have better results. If osteoarthritis has already occurred, a complete joint replacement with a joint endoprosthesis may be necessary.
What complications can occur with cartilage damage?
Cartilage damage can lead to severe pain and restricted mobility. If cartilage damage is not treated, the joint cartilage can no longer regenerate. This can result in complete cartilage wear and osteoarthritis, which is associated with severe pain. If the joint space becomes narrower due to the progressive breakdown of the cartilage, the joint becomes unstable. The body tries to compensate for the defect with bone growths. These bone attachments cannot replace the cartilage and can hinder movement. This causes severe pain during movement and sometimes even at rest. To prevent this, treatment should be carried out as early as possible.
