What Is Cartilage Damage? What Is Articular Cartilage Damage?

Cartilage structures and functions can relatively easily be harmed, often resulting in damage. Cartilage is a tough, flexible connective tissue that is found in many areas of the body. This fine, rubbery tissue mainly functions as a cushion for bones at joints. The English word "cartilage" comes from the Latin word cartilage, which means "cartilage" or "gristle".

Cartilage has several functions:

Shock absorber: Cartilage covers the surface of joints, allowing bones to slide over one another. It reduces any friction, prevents any damage and helps to support weight when moving, bending, stretching or running.

Acts as a mould: the tough, flexible cartilage tissue forms specially shaped and curved body parts that would otherwise have no support from the bones. For instance, the outside of the ears and most of the nose are made up of cartilage.

However, cartilage unlike other types of tissue does not have a blood supply. Blood cells help repair tissue damage. As a result, unlike damaged skin or muscles that can heal, damaged cartilage will not heal quickly.

There are three types of cartilage:

Elastic cartilage is the most springy and supple type of cartilage. This type of cartilage makes up the outside of the ears, some of the nose, and also the epiglottis.

Fibrocartilage is the toughest type of cartilage, and it is able to withstand a great deal of weight. It is found between the discs and vertebrae of the spine and between the bones in the hips and pelvis.

Hyaline cartilage is both springy and tough. It is found between the ribs, around the windpipe, and between the joints. The cartilage between the joints is known as articular cartilage.

Types of cartilage damage

All three types of cartilage can be damaged. A blow to the ear can damage the elastic cartilage, causing the ear to appear deformed. Or, the fibro cartilage between the discs of the back can become damaged, resulting in a slipped disc.

One of the most common and potentially serious types of cartilage damage occurs in the articular cartilage that lies in between a joint, usually the knee joint. This can cause pain, swelling, and some loss of mobility. Articular cartilage damage is not life threatening, but does strongly affect the quality of life. This damage is often the cause of severe pain, swellings, handicapped mobility and severe restrictions to the patient's activities.

What are the signs and symptoms of cartilage damage?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor notice. For example, pain may be a symptom while a rash may be a sign.

The symptoms of articular cartilage damage include:

decreased range of movement in the affected joint
joint pain
stiffness
swelling

If the damage is particularly severe, a piece of cartilage can break off and become loose. In this case, the loose piece of cartilage may affect the movement of the joint. This can cause a feeling of the joint 'locking' or catching. Sometimes, the joint may also give way.

What are the causes of cartilage damage?

Direct blow: Articular cartilage damage can occur as a result of a sudden, direct blow to the cartilage. This can happen, for example, when falling directly onto the knees. This is why cartilage damage is often a problem for people who play sports that involve physical contact,such as football, rugby, and some martial arts.

'Wear and tear': Cartilage can also become damaged gradually, over time. There is an increased risk of developing this type of cartilage damage for overweight individuals, or for people with a problem with the structure of the joint. This type of long-term damage to the cartilage is known as osteoarthritis.

Immobility: Being immobile for a long period can also damage the cartilage. It requires regular movement in order for it to function properly.

Articular cartilage has a very limited capacity for self repair. Small damage does not repair itself and can often get worse over time.

How is cartilage damage diagnosed?

Diagnosing articular cartilage damage can be difficult. The diagnosis cannot be confirmed through physical examination. In addition, the symptoms are similar to the ones of other types of knee injuries, such as a sprain or a damaged ligament.

Magnetic resonance imaging (MRI): MRI scans use strong magnetic fields and radio waves to produce detailed images of the inside of the body. It can often detect cartilage damage.

Arthroscopy: This is a form of 'keyhole surgery' where the surgeon makes a small incision into the joint. An arthroscope (a small, flexible tube with a camera) is used to look inside the joint.

Arthroscopies can be carried out under local anesthetic and there is no need for an overnight stay at the hospital.

Grading of cartilage damage

After an arthroscopy, the extent of the damage can be determined. Cartilage damage is measured in grades from zero to four:
- Grade 0 - the cartilage is healthy, undamaged and intact.
- Grade 1 - the cartilage has some blistering and soft spots.
- Grade 2 - there is a minor defect (less than 50 percent) in the cartilage. There are minor tears in the surface of the cartilage.
- Grade 3 - there is a deeper defect (more than 50 percent), deep crevices in the cartilage.
- Grade 4 - the cartilage has lost all of its thickness, leaving the bones of the joint exposed.
The grading does not always correspond to the level of pain. For example, one person may have severe pain as a result of grade-one damage, while another person who has sustained extensive damage may experience very little pain. Pain is not a good indicator of the extent of the damage. Also, the size of each defect will be measured as well as its location.

What is the treatment for cartilage damage?

There are a number of non-surgical treatments that can help to relieve the symptoms of damaged articular cartilage:

Physiotherapy: A set of exercises that strengthen the muscles surrounding or supporting the joint. This may help to reduce the pressure on the joint, and reduce pain.

Painkillers: non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, can help to reduce swelling and pain. Avoid taking ibuprofen if there is history of stomach problems, such as a peptic ulcer.

Supportive devices: for example, a cane, or a leg brace.

Lifestyle changes: for example, reducing activity that involves the affected joint.

Non-surgical treatment may only provide short-term relief and surgery may be required in more severe cases.

Surgical treatment

Arthroscopic lavage and debridement: It is a technique that is used when pieces of cartilage have become loose in the joint, causing the joint to lock up. An arthroscope (a flexible tube with a camera on the end) is used to enter the joint, before literally 'washing out' the joint using a saline solution.

The technique cannot repair the damaged cartilage, but it can help to reduce the pain and increase mobility.

Marrow stimulation: It is a procedure that involves drilling tiny holes (micro fractures) into the bone underneath the damaged cartilage. This exposes the blood vessels inside the bone. As a result, it leads to the formation of a blood clot within the damaged cartilage. The blood cells then begin to stimulate the production of new cartilage. The disadvantage to the procedure is that the newly generated cartilage is fibro cartilage rather than hyaline cartilage. Fibro cartilage is not as supple as hyaline cartilage. Therefore, there is a risk that it can wear away after a few years in some cases. Further surgery may be required.

Mosaicplasty: It is a new technique that involves removing healthy cartilage from the non-weight bearing areas of a joint, such as the side of the knee. It is then used to replace the damaged cartilage.

Mosaicplasty appears to be successful in most people. However, there is not enough available evidence to determine what the possible long-term advantages and drawbacks of the technique may be.

As it is a new procedure, the possible risks and benefits of the technique should be fully discussed with the surgeon.

Autologous chondrocyte implantation (ACI) : It is another new technique where a small sample of cartilage cells is taken from the edge of the knee.

The cells are then sent to a laboratory and placed in an incubator, where they are given nutrients. This encourages them to divide and produce new cells. After a few weeks, the number of cartilage cells will have increased by 50 times from their original number. The new cartilage will be used to replace the damaged cartilage.

The National Institute for Health and Clinical Excellence (NICE), UK, has studied ACI and determined that there is not enough evidence about its long-term effects or safety. It is only available as part of a clinical trial or in a number of private clinics. The possible risks and benefits should be fully discussed with the surgeon before choosing to have the procedure.

Rehabilitation

Rehabilitation following any articular cartilage repair procedure is essential for the success of any articular cartilage resurfacing technique. The rehabilitation is often long and demanding. Mainly because it takes a long time for the cartilage cells to adapt and mature into repair tissue. Cartilage is a slow adapting substance.