What is the cause of Osgoods Schlatters Disease?

Hiya,
Last Friday I was diagnosed with 'Osgood Schlatters'.
It's a confuzing name, for quite a common problem.
Let me tell you a little more:
Osgood-Schlatter's disease usuall occurs in teenagers. It causes pain and swelling just below the knee. It is named after the two people who first described it. It is not serious and usually goes away in time.
Young teenagers, particuarly boys, are the most commonly affected. It is uncommon over the age of 16. It is more common in teenagers who play a lot of sport involving kicking, running or jumping. These kinds of sports cause repeated and vigorous use of the quadriceps muscles. However, it can also occur in children who are not sporty.
The main symptom is pain just below the kneecap (patella). The severity of the pain tends to flare up and down. It is usually worse during, and just after, activity. It tends to ease with rest.
The pain typically lasts a few months, but sometimes persists until you have finished growing. This means that in some cases it can last up to two years.
A small, tender, bony bump may develop a few centimetres below the kneecap. This occurs where the patella ligament attatches to the tibia (shin bone). The small bump is permanent, although in time it becomes painless. The actual knee joint is not affected, so knee movements are normal. Symptoms usually occur just under one kneecaps, but in up to one in three cases it affects the area under both kneecaps.
No tests are usually needsas the diagnosis is often clear from the typical symptoms.
Sometimes it develops for no apparent reason. However, overuse of the front thigh muscles (quadriceps) is thought to be a common cause. The quadriceps muscle is used to straighten the knee. This muscle pulls on the patella, which pulls on the patella ligament, which is attached to the upper part of the tibia.
Overuse of the quadriceps muscle can cause repeated stress and strain on the attachment of the patella ligament to the growing tibia. This can cause inflammation and pain at the site of the ligament attachment. In some cases, and small flake of bone is pulled off the tibia by the pulling ligament. Healing bone (callus) then forms which may cause a hard bony bump to develop.
The pain usually goes within a few months without any treatment. It may helps to be reassured that the condition is not serious and is likely to go. However, paracetamol of ibuprofen may be useful to take to relieve the pain when it flares up.
Sport or physical activity is not likely to cause any permanent damage, but may make the pain worse. However, it is often sporty teenagers who develop Osgood-Schlatter's disease. Difficult decisions may have to be made about training schedules and sporting commitments. Each case is different, and your doctor will be able to advise you.
An approach similar to the following may be advised:

• You do not usually need to stop sport. However, easing off strenuous of vigorous sport may be sensible for a while until the pain eases to a tolerable level. You should aim to reduce the duration, frequency and also intensity of your exercise, especially if this exercise includes running or jumping. Consider a complete break from sport for a while if pain remains bad.
• An ice pack applied below the kneecap for about five minutes before and after exercise may prevent some inflammation and pain.
• Consider wearing knee pads during sports such as football and rugby to protect the tender area.
• Consider seeing a physiotherapist for advise on exercises to strengthen the quadriceps muscles.

As mentioned, although the pain typically only lasts a few weeks or months, it can sometimes last longer; up to two years. However, in around 9 out of 10 cases the pain resolves completely after this time. Some people find that the pain only recurs when they kneel.
In very few cases, a small operation may be required if pain continues. This can involve removing unhealed areas of flakes of bone or fixing them to the tibia. This usually leads to excellent results.