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 injuries, 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 to produce detailed images of the inside of your body.

However, access to MRI scans can be limited 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.

Arthroscopy

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 camera) to look inside your joint.

An arthroscopy is usually carried out under general anaesthetic. In some cases, however, a spinal or local anaesthetic is used.

An arthroscopy is usually performed as a day case procedure, which means the person being treated is able to go home on the same day as the surgery.

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% of the total thickness) 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.

A more important consideration, therefore, is how the damaged cartilage affects the underlying structure and mechanics of the joint it supports.

Cartilage damage is a relatively common type of injury. The majority of cases involve the knee joint.

Symptoms of cartilage damage include:

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

Cartilage

Cartilage is a tough, flexible tissue found throughout the body. Cartilage serves two main functions:

• a shock absorber
• 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 repair damaged tissue, so 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 – this makes up the outside of the ears, some of the nose and the epiglottis (the flap of tissue at the back of the throat that prevents food going down into your airways)
• fibrocartilage – found between the discs (vertebrae) of the spine and between the bones of the hips and pelvis
• articular (hyaline) cartilage – a springy and tough type of cartilage found between the ribs, around the windpipe (trachea) and between the joints

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.

This article focuses on articular cartilage damage.

Causes of articular cartilage damage

Articular cartilage damage is one of the most common and potentially serious types of cartilage damage, and usually affects the knee joint. The damage can result in pain, swelling and some loss of mobility.

There are three main ways the articular cartilage can be damaged:

• a sudden accidental injury – for example, a fall or a sports injury
• osteoarthritis – this type of long-term cartilage damage to the joints is more likely if you’ve had your meniscus removed, are overweight, or have a problem with your joint structure
• osteochondritis dissecans – where a small section of cartilage and a piece of bone attached to it comes away from a joint
• infection

Treatment

Non-surgical treatments, such as physiotherapy and non-steroidal anti-inflammatory drugs (NSAIDs), are usually recommended for minor to moderate cases of cartilage damage.

Surgery may be required in more serious cases. 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 joint and using it to replace damaged cartilage.

In the most serious cases, the entire joint may need to be replaced with an artificial joint, such as a knee replacement or hip replacement.

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 damage do not seek medical help. However, it is thought to be quite common.

Every year around 10,000 people in the UK 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 the age of 50. It is also more common in women than in men.

The symptoms of articular cartilage damage include swelling, joint pain, stiffness and 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, which is known as haemarthrosis.

There may also be swelling and dark red blotches on the skin that are similar to bruises.

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 GP if you suspect you have damaged your cartilage. You may need to be referred to a specialist in hospital for assessment and treatment as it can be difficult to tell how severe the cartilage damage is.

There are a number of surgical and non-surgical treatments that can help relieve symptoms of damaged articular cartilage, depending on how severe the damage is.

Non-surgical treatment

Non-surgical options may include:

• physiotherapy – exercises that strengthen the muscles surrounding or supporting your joint, which may help reduce both pain and pressure on the joint
• painkillers – non-steroidal anti-inflammatory drugs (NSAIDs) can help reduce swelling and pain
• 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

Surgical treatment for damaged articular cartilage includes the following procedures:

• arthroscopic lavage and debridement
• marrow stimulation
• mosaicplasty
• allograft osteochondral transplantation
• autologous chondrocyte implantation

These procedures are described in more detail below.

Marrow stimulation

Marrow stimulation involves making tiny holes called 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

Mosaicplasty is a technique where small dowels (rods) of healthy cartilage from the non-weightbearing areas of a joint, such as the side of the knee, are removed and used to replace the damaged cartilage.

Mosaicplasty can be successful in most people. However, it is only suitable for treating relatively small areas of cartilage damage. This is because removing too much healthy cartilage could damage the section of the body where the cartilage was taken from. 

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. 

Unlike mosaicplasty, large areas can be covered by this technique. This procedure will need special funding from your clinical commissioning group (CCG).

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 from 2 to 20 million. 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 or glued on to the damaged area, usually through a small incision.

After studying ACI, the National Institute for Health and Care Excellence (NICE) decided there is not enough evidence about the procedure’s long-term effects or safety. The procedure is therefore currently only offered by very few hospitals.

However, a number of private clinics may offer ACI. The cost of treatment can be expensive and depends on the complexity of the operation. In some cases, you may have to pay in the region of £25,000.

Artificial scaffolds

A new technique being used to treat cartilage damage involves implanting an artificial scaffold into the damaged area. The scaffold can be either a patch or gel, and is usually made up of a combination of collagen and proteins.

They can be used in combination with microfracture or on their own. Some recent techniques include soaking the scaffold in bone marrow to attempt to use stem cells to repair the cartilage.

The frame helps bone marrow cells form cartilage, and is gradually absorbed over time until only the regenerated cartilage remains.

This technique is not currently widely available on the NHS, however.  

Ongoing research

A number of ongoing research projects are currently investigating more efficient and effective ways of repairing cartilage.

Examples of current research projects include:

• investigating ways of using different sources of stem cells to generate new cartilage (for example, bone marrow or fat)
• using donor stem cells to regenerate cartilage
• combining cartilage and stem cells to improve repair

Although these projects are still in the early stages, researchers are optimistic they will lead to new kinds of treatment.