I have problem with my left knee which makes a small grinding noise. It has been going on for a while now, I play soccer but I can't remember if it was a sport injury or not. There is no pain involved but it just worrier's me a lot...

Is there any particular disease associated with this or can it just be a sporting injury?

That grinding sound is no good. Bone on bone. Contact a sports med. Orthapedic right away. If you are near ny I have a good one for you.

Is there any long term effects that can be brought by this?

Yes arthritis and debilitating pain