I have dirt trapped in my kneecap...?

A few years ago I fell down outside. I scraped my knee up pretty badly, and because I fell in dirt, a lot of dirt got in the wound. I was dumb and terrified of the pain I would get from cleaning it out completely, so I didn't. Stupid, I know. The wound healed nicely, except for the fact that there is a bunch of dirt trapped in my kneecap under the skin. What can I do, outside of reopen the wound? Should I do anything? Keep in mind, this was yeaaaars ago. The wound is completely healed, with brown streaks visible of where the dirt still is under a few layers of skin. There never has been any sign of infection or anything outside of the fact that I have a colored knee now.