What Kelly321 said - although I am sure you are fine if you have no other problems.
I wanted to add: don't let an orthopedic-type injury go untreated while you're pregnant. A simple knee sprain is a lot harder to deal with when you can't (or would rather not) take naproxen / get x-rays / try cortisone shots. So really, really don't be shy about getting swollen joints or other minor injuries treated early, when the safer, more conservative treatments are most efficacious.