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.