Last updated on 5 January 2022
What is cartilage?
The cartilage is a connective rubbery tissue that acts as a cushion between the bones of joints. It is easily damaged and, because it does not contain blood vessels or nerves, it takes much longer to heal than normal tissue.
When cartilage in a joint, known as articular cartilage, is damaged, it can cause severe pain, inflammation and some degree of disability. This type of cartilage damage occurs most commonly in the knee, but the elbow, wrist, ankle, shoulder and hip joint can also be affected.
What causes knee cartilage damage?
Damage to the knee cartilage can occur as a result of trauma, such as an accident, or through progressive degeneration, sometimes called wear and tear.
Certain activities are also more likely to cause articular cartilage damage. These include:
High-impact sports injuries
A direct blow to the joint can cause cartilage damage. This is very common in people who are active in high-impact sports.
Conversely, inactivity can result in cartilage damage too, particularly for ‘weekend warriors’ who participate in sports only at the weekend and are therefore more prone to injury from the sudden burst of intense activity. Your joints need to move regularly to remain healthy. If you go through long periods of inactivity, you increase the risk of damage to the cartilage.
Obesity and long-term stress on joints
Long periods of stress on your joints can also result in cartilage damage. This is especially so in load-bearing joints like the knee joints if you are overweight or obese. This prolonged stress can eventually lead to loss of cartilage in the joints, known as osteoarthritis.
Symptoms of knee cartilage damage
If you have damaged knee cartilage, you may experience symptoms such as:
- Joint pain even while resting, that increases when weight is put on the joint
- Swelling around the knee
- Stiffness in the knee
- A clicking or grinding sensation during movement
- Sensation of the knee joint locking, catching, or giving way
How to diagnose knee cartilage damage?
Symptoms of a sprain, ligament damage and cartilage damage can often be similar, making it difficult to differentiate one from the other. However, with today’s non-invasive tests, diagnosis is much easier than it used to be.
To confirm the source of your pain, your doctor may order the following diagnostic tests:
Magnetic resonance imaging (MRI)
In an MRI, a magnetic field and radio waves create detailed images of the body, but this procedure may not always detect cartilage damage.
A tube-like instrument called an arthroscope is inserted into your joint to examine it. An arthroscopy can help determine the extent of your cartilage damage.
Treating knee cartilage damage?
If your injury is not severe, non-surgical treatments such as injections and supplementations may suffice in treating your knee cartilage damage. Your doctor may suggest one of the following:
Many patients ask for the magic bullet or miracle injection therapy. This can be as simple as a cortisone injection (sometimes called a H+L), which subdues inflammation and gives instant pain relief. However, this is akin to putting a band aid on the problem as it does not treat the root cause and its results are temporary.
This procedure, where a thick fluid called hyaluronic acid is injected into the joint, is recommended for patients with small early cartilage defects or injuries. Hyaluronic acid acts as a lubricant to enable bones to move smoothly over each other and as a shock absorber for joint load. These treatments are typically repeated every 6 to 12 months as the knee’s response to the hyaluronic acid diminishes over time.
Platelet-rich plasma injections
Over the past several years, much has been written about a preparation called platelet-rich plasma (PRP), although its potential effectiveness in the treatment of injuries is inconclusive.
Platelets are blood cells that contain proteins that help wounds to heal. Researchers theorise that, by injecting areas of inflammation or tissue damage with high concentrations of platelets, it can encourage wounds in this area to heal.
Your doctor will take a small blood sample from you. This will be put into a centrifuge or other specialised device that spins at high speed to separates the platelets from other blood components. The concentration of platelets is then injected into the area of your body that needs to be treated.
Because the injection contains a high concentration of platelets, which can be from 5 to 10 times more than the untreated blood, doctors theorise that the platelets will speed up healing. Many famous athletes – Tiger Woods, tennis star Rafael Nadal, and several others – have received PRP for various problems, such as sprained knees and chronic tendon injuries, and some have credited PRP with their being able to return more quickly to competition.
Stem cell therapy
Stem cell therapy is being lauded as a miracle cure for almost everything, but there is little scientific evidence to back this up, with the exception of stem cell therapy for the knees.
Until recently, treatment options for osteoarthritis in the knee joints were either temporary or surgical. But treatments with stem cell therapy have resulted in decreased inflammation, reduced pain and repaired cartilage. In fact, many people have successfully avoided knee surgery through this treatment method.
In the procedure, adult stem cells are extracted from bone marrow or fat through simple methods. It is then concentrated and injected into the knee with image guidance, usually to with successful results.
Stem cell therapy has great potential for healing cartilage damage. However, it has remained unclear whether stem cells are responsible for regeneration or whether they trigger the process. This is a very new treatment and different laboratories yield very different results, but it is beginning to show much promise.
Surgical treatment for knee cartilage repair
Surgery is usually offered for severe disease that do not seem to respond to conservative treatments. There are several surgical options available depending on your age, activity level, extent of cartilage damage and how long ago the injury happened.
Have a careful discussion with your doctor to determine if surgery is needed, and which surgical procedure will best treat your knee cartilage damage.
Surgical options include:
Your surgeon will smoothen the damaged cartilage and remove loose edges to prevent it from rubbing and irritating the joint.
Your surgeon will drill tiny holes (micro-fractures) under the cartilage, exposing the blood vessels that lie inside the bone. This causes a blood clot to form inside the cartilage, triggering new cartilage to form. This clot eventually matures into firm repair tissue that becomes smooth and durable.
Since this maturing process is gradual, it usually takes 2 to 6 months for the patient to experience improvement in the pain and function of the knee. Improvement is likely to continue for about 2 to 3 years. Unfortunately, the new cartilage that grows is less supple than the original cartilage. This means it wears away more quickly, and you may need further surgery later on.
Your surgeon will take healthy, undamaged cartilage from one area and move it to the damaged site. This procedure is only used for isolated areas of cartilage damage, generally limited to 10 to 20mm in size, so it is not suitable in cases where damage is more widespread, as in osteoarthritis. It is typically used in patients under the age of 50 who damaged their cartilage in an accident.
Autologous chondrocyte implantation
A small piece of cartilage is removed and taken to a laboratory, where it is grown to produce more cartilage cells. About 1 to 3 months later, the new cartilage cells are implanted into the joint, where they grow into healthy tissue.
Arthroscopic knee surgery
Specifically for the knee, this procedure involves your surgeon making a very small incision and inserting a tiny camera – called an arthroscope – into your knee. This allows your surgeon to view the inside of the joint on a screen and, if necessary and possible, correct the issue using small instruments within the arthroscope.
Cartilage regeneration, known as membrane-induced autologous chondrocyte implantation (MACI), harvests cartilage-forming cells from your body and surgically implants them into the damaged area to restore the cartilage.
While cartilage damage cannot heal on its own, there are various treatment options available. Depending on the degree of your cartilage damage, it is possible to treat your injuries using non-surgical as well as surgical treatments. If you suffer cartilage damage, make sure to consult a doctor on which is the best treatment option for you.
Article reviewed by Dr Chin Pak Lin, orthopaedic surgeon at Gleneagles Hospital
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