Cartilage damage is a relatively common type of injury. The majority of cases involve the knee joint.
Symptoms of cartilage damage include:
- joint pain
- a decreased range of movement in the affected joint
Cartilage is a tough, flexible tissue found throughout the body. Cartilage serves two main functions:
- it acts as a shock absorber
- it acts as a mould
Cartilage covers the surface of joints, enabling bones to slide over one another while reducing friction and preventing damage. It helps to support your weight when you move, bend, stretch and run.
The tough, flexible cartilage tissue is ideal for creating specially shaped and curved body parts that would otherwise have no support from the bones. For example, most of the nose and the outside of the ears are made up of cartilage tissue.
Unlike other types of tissue, cartilage does not have its own blood supply. Blood cells help to repair damaged tissue, therefore damaged cartilage does not heal as quickly as damaged skin or muscles.
Types of cartilage
There are three types of cartilage. They are:
- elastic cartilage
- hyaline cartilage
These are described in more detail below.
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 the epiglottis (the flap of tissue at the back of the throat, which prevents food going down into your airways).
Fibrocartilage is the toughest type of cartilage and can withstand a great deal of weight. It is found between the discs (vertebrae) of the spine and between the bones of the hips and pelvis.
Hyaline cartilage, also known as articular cartilage, is both springy and tough. It is found between the ribs, around the windpipe (trachea) and between the joints.
Types of cartilage damage
All three types of cartilage can be damaged. For example, a blow to your ear can damage the elastic cartilage, making your ear look deformed. This condition is often seen in rugby players and is known as ‘cauliflower ear’.
The fibrocartilage between the discs in your back can also become damaged, resulting in a slipped disc.
One of the most common and potentially serious types of cartilage damage is damage to the articular cartilage between a joint (usually the knee joint). The damage can result in pain, swelling and some loss of mobility.
There are three main ways that the articular cartilage can be damaged:
- as a result of a sudden accidental injury to the cartilage – for example, falling badly and landing on your knees
- where a small section of cartilage and a piece of bone attached to it comes away from a joint – this is known as osteochondritis dissecans
- long-term damage that occurs due to a process of ‘wear and tear’ – this type of long-term cartilage damage to the joints is known as osteoarthritis.
(The rest of this article focuses on articular cartilage damage.)
Read more about the causes of cartilage damage.
In more serious cases surgery may be required. There are a number of surgical techniques available, such as encouraging the growth of new cartilage, or taking a piece of healthy cartilage from elsewhere in the body and using it to replace damaged cartilage.
Read more about the treatment of cartilage damage.
How common is cartilage damage?
It is hard to estimate exactly how common cartilage damage is because many people with mild cartilage damage do not seek medical help. However, cartilage damage is thought to be quite common.
Every year in the UK, around 10,000 people have cartilage damage serious enough to require treatment.
Cases of accidental cartilage damage are most common in people under 35 years old. This is because this age group is more likely to take part in sporting activities where there is a higher risk of injury.
Cartilage damage associated with osteoarthritis is more common in adults over 50 years old. It is also more common in women than in men.
Symptoms of cartilage damage include:
- joint pain
- a decreased range of movement in the affected joint
If the damage is severe, a piece of cartilage can break off and become loose. If this happens, the loose piece of cartilage may affect the movement of your joint. This can cause a feeling of the joint ‘locking’ or catching. Sometimes, the joint may also give way.
The most common location for cartilage damage is in the knee joint. In some cases of knee joint damage, bleeding can occur inside the knee joint. This is known as haemarthrosis and can lead to skin around the joint swelling up. Dark red blotches similar to bruises may also develop on the skin.
Less common locations for cartilage damage include:
- the shoulder
- the hip joint
- the elbow
- the wrist
- the ankle
When to seek medical advice
Always visit your doctor if you suspect you have damaged your cartilage. It can be difficult to assess the severity of the damage so a medical diagnosis is advisable.
Articular cartilage damage can occur as a result of a sudden, direct blow to the cartilage. For example, your cartilage can be damaged if you have a bad fall directly onto your knees, or following a bad tackle while playing football or rugby.
This is why cartilage damage often occurs in people who play physical contact sports.
Read more about sports injuries.
Cartilage can also be damaged gradually over time through ‘wear and tear’. Your risk of developing this type of cartilage damage is increased if you are overweight or have a problem with the structure of your joint. This type of long-term damage to the cartilage is known as osteoarthritis.
Diagnosing articular cartilage damage can be challenging because it cannot be confirmed through a physical examination. Also, the symptoms are often similar to other types of knee injures, such as a sprain or a damaged ligament.
Magnetic resonance imaging (MRI)
Magnetic resonance imaging (MRI) scans are often used for detecting cartilage damage. MRI scans use strong magnetic fields and radio waves to produce detailed images of the inside of your body.
However, access to MRI scans is limited in many primary care trusts (PCTs), and patients with life-threatening conditions are usually given priority. You may have to wait a considerable amount of time before you can have a MRI scan.
If you have articular cartilage damage, another option is to have an arthroscopy. This is a form of ‘keyhole surgery’ where the surgeon makes a small cut in your joint. They will then use an arthroscope (a small, flexible tube with a camera on the end) to look inside your joint.
Arthroscopies are often carried out under local anaesthetic where painkilling medication is used to numb the joint. This means that you may not have to spend the night in hospital.
Read more about having an arthroscopy.
Grading cartilage damage
After having an arthroscopy, your surgeon should be able to determine the extent of the damage. Cartilage damage is measured in grades from 0 to 4, where grade 0 indicates no damage and grade 4 indicates severe damage. The grades are described in more detail below.
- Grade 0: the cartilage is undamaged and intact
- Grade 1: the cartilage has some blistering and softening
- Grade 2: there is a minor defect (less than 50%) in the cartilage, or minor tears in the surface of the cartilage
- Grade 3: there is a deeper defect (more than 50%) in the cartilage
- Grade 4: the cartilage has lost all of its thickness, leaving the bones of the joint exposed
The grading of cartilage damage does not always correspond to the level of pain you feel.
For example, one person may feel severe pain as a result of grade 1 cartilage damage, whereas another person who has extensive damage may experience very little pain.
Therefore, a more important consideration is how the damaged cartilage affects the underlying structure and mechanics of the joint that it supports.
There are a number of non-surgical treatments that can help to relieve symptoms of damaged articular cartilage. They are described below.
- Physiotherapy – exercises that strengthen the muscles surrounding or supporting your joint which may help reduce pressure on the joint and reduce pain.
- Painkillers – non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can help reduce swelling and pain. However, avoid taking ibuprofen if you have, or have had, a stomach problem, such as a stomach ulcer.
- Supportive devices – such as a cane or leg brace.
- Lifestyle changes – such as reducing activity that involves the affected joint.
In more severe cases of articular cartilage damage, non-surgical treatment may only provide short-term relief and surgery may be required.
Surgical treatment for damaged articular cartilage includes the following procedures:
- arthroscopic lavage and debridement
- marrow stimulation
- allograft osteochondral transplantation
- autologous chondrocyte implantation
These procedures are described in more detail below.
Arthroscopic lavage and debridement
Arthroscopic lavage and debridement is a technique used when pieces of cartilage have become loose in the joint, causing the joint to lock.
The surgeon makes a cut in the joint before using an arthroscope (a flexible tube with a camera on the end) to assess the damage. They then ‘clean out’ the joint using a saline (salt) solution. Loose cartilage fragments are removed using a device known as a shaver, which works in a similar way to a vacuum cleaner.
Arthroscopic lavage and debridement cannot repair the damaged cartilage, but it can help reduce pain and increase mobility.
Marrow stimulation involves making tiny holes (microfractures) into the bone beneath the damaged cartilage using a small pointed instrument known as an awl. This releases the bone marrow from inside the bone and leads to a blood clot forming within the damaged cartilage.
The marrow cells then begin to stimulate production of new cartilage. The drawback to marrow stimulation is that the newly generated cartilage is fibrocartilage rather than hyaline cartilage. As fibrocartilage is not as supple as hyaline cartilage, there is a risk that after a few years it will wear away and further surgery may be needed.
Mosaicplasty is a technique where small rods of healthy cartilage from the non-weight-bearing areas of a joint, such as the side of the knee, are removed and used to replace the damaged cartilage.
Mosaicplasty seems to be successful in most people. However it is only suitable for treating relatively minor cartilage injury. This is because removing too much healthy cartilage could damage the section of the body from where the cartilage was taken.
Before having mosaicplasty, your surgeon should discuss the possible risks and benefits of the technique with you.
Allograft osteochondral transplantation (AOT)
If damage to your cartilage is thought too extensive to be treated with mosaicplasty an alternative procedure called allograft osteochondral transplantation (AOT) may be considered.
AOT is a similar procedure to mosaicplasty, but the cartilage is obtained from a recently deceased donor. The cartilage will be tested in a laboratory to make sure it is free from infection before being prepared for transplant.
Autologous chondrocyte implantation (ACI)
Autologous chondrocyte implantation (ACI) uses a two-stage technique. During the first stage the surgeon takes a small sample of cartilage cells from the edge of your knee during an arthroscopy.
The cells are sent to a laboratory and placed in an incubator where they are given nutrients to encourage them to divide and produce new cells. After a few weeks, the number of cartilage cells will have increased by 50 times. The new cartilage cells are used to replace the damaged cartilage.
The second stage involves placing these cells on a collagen patch, which is then sutured/glued onto the damaged area usually through a small incision.
After studying ACI, the National Institute for Health and Clinical Excellence (NICE) has decided there is not enough evidence about the procedure’s long-term effects or safety. Therefore ACI is not available on the NHS unless as part of a clinical trial (a type of research that tests one treatment against another).
A new technique used to treat cartilage damage is known as an artificial scaffold. This involves implanting a frame (the artificial scaffold), made up of a combination of collagen and proteins, into a damaged joint.
The frame stimulates growth of new cartilage cells and over time is gradually absorbed into the new cartilage tissue until only cartilage remains.
A number of ongoing research projects are currently investigating more efficient and effective ways of repairing cartilage. Examples of current research projects include:
- creating hybrid cartilage by combining human cells with synthetic fibres
- investigating ways of using stem cells to generate new cartilage
Although these projects are still in their early stages, researchers are optimistic they will lead to new kinds of treatment.