Chondromalacia

What is the patella?

The patella is the kneecap bone. It lies within the quadriceps tendon. This large tendon from the powerful thigh muscles (quadriceps) wraps round the patella and inserts into the top of the lower leg bone (tibia). The quadriceps muscles straighten the leg. The patella acts like a fulcrum to increase the force of the quadriceps muscle.

The back of the patella is covered with smooth cartilage. This helps the patella to glide over the lower part of the thigh bone (femur) when you straighten your leg.

What is chondromalacia?

Chondromalacia (sometimes called chondromalacia patellae) is damage to the patella cartilage. It is like a 'softening' or 'wear and tear' of the cartilage. The roughening or damage can range from slight to severe.

What causes chondromalacia?

Chondromalacia occurs most often in young adults and teenagers. It is more common in women. The reason why damage occurs to the cartilage is not clear. It is thought that the patella may rub against the lower thigh bone instead of gliding smoothly over it. This may damage the patella cartilage. Situations where this is more likely include the following.

• Overuse of the knee, such as in certain sports.
• Some people may have a slight problem in the alignment of the knee. This may cause the patella to rub on rather than glide over the lower femur. It may be just the way some peoples knee develops. It may also be due to an imbalance in the strength of the parts of the quadriceps muscle. If one side pulls harder than the other then the patella may not glide 'true' and may rub on one side.
• A slight problem with alignment and overuse with sports may be the commonest reason for the condition to develop.
• Injury to the knee.
• In older people it may develop as part of the ageing process where there is 'wear and tear' of cartilage in many joints.

What are the symptoms of chondromalacia?

• Pain around the knee. In mild cases it is a vague pain that is difficult to localise and may come and go. In others the pain may be permanent, bad and localised to a particular point on the knee. The pain is typically worse when walking down stairs or down hills. It may be brought on by sitting with the knees bent for long periods.
• A grating or grinding feeling or noise when the knee moves knee.
• The knee may feel as if it 'gives' at times.
• Stiffness in the knee.

• Avoid strenuous use of the knee - until the pain eases. Symptoms usually improve in time if the knee is not over used.
• Painkillers - such as regular paracetamol or anti-inflammatory painkillers such as ibuprofen may be advised to ease the pain.
• Physiotherapy - improving the strength of the muscles around the knee will ease the stress on the knee. Also specific exercises may help correct problems with alignment and muscle balance around the knee. Strengthening the inner side of the quadriceps muscle to counteract an imbalance when it pulls on the patella is the sort of treatment that may be advised.
• Surgery - may be advised if the above treatments have not helped. It is not commonly done as the above measures usually work.
  • Arthroscopic surgery is the usual operation. This is where a tiny flexible camera is inserted into the knee to see exactly what the cartilage looks like. By using fine surgical instruments the cartilage can be 'shaved' to remove roughened areas
  • In more severe cases surgery may be needed to correct the alignment of the patella. This is done to stop any constant rubbing and friction between the back of the back of the patella and the lower femur. For example, tight ligaments on the side of the patella may be cut to allow it to move over slightly.

In summary

• Chondromalacia causes knee pain.
• It usually goes in time.
• Avoid overuse of the knee till symptoms go.
• Physiotherapy to strengthen muscles around the knee is commonly advised.
• Surgery to shave the roughened cartilage or to realign the patella is occasionally needed.

© EMIS and PIP 2004   Updated: May 2001   CHIQ Accredited