Why fluid builds up in the knee
There is normally a small amount of fluid inside the knee joint, which keeps the joint lubricated. When wear, inflammation, injury, gout or infection makes this fluid increase, the knee swells, feels heavy and is hard to bend. This is commonly called “water on the knee”.
Draining the fluid (aspiration)
The built-up fluid is drawn out with a fine needle under ultrasound. This:
- quickly reduces pressure and pain in the knee
- makes the knee easier to bend
- allows the fluid to be tested, if needed, to find causes such as infection or gout
Many people wrongly believe that once fluid is drained it will keep coming back. In fact it comes back only if the underlying cause is not treated, not because it was drained.
Why PRP afterwards
When fluid builds up because of wear, draining it is not enough: the inflammation in the joint also needs attention. After the fluid is drained, PRP can be given into the joint at the same time under ultrasound guidance. PRP helps reduce inflammation and pain and improves the environment inside the joint.
Important warning
If the knee suddenly becomes red, hot and very swollen, with a fever, it may be an infection. In that case, see a doctor quickly without delay.
This article is for general health information. Always consult a doctor for your own diagnosis and treatment.
