Even if your knee injury happened a while ago, it can still cause pain. But so can many other things, including arthritis and other conditions. To find out what’s going on in your case, you’ll need to see your doctor.
At that visit, you’ll talk about your symptoms and the injury. You’ll also get a physical exam, and you may need to get an X-ray, MRI, CT scan, or other tests.
In addition to redness, swelling, bruising, and discoloration, your doctor will check for differences in your muscles. Knee pain often happens the when the outer muscles of the thigh are stronger than those in the mid-thigh (causing the kneecap to be pulled “off track”), so your doctor will pay particular attention to the vastus medialis, a muscle in your mid-thigh that extends to the knee.
You doctor will also feel your knee, checking for pain, warmth, and swelling. They will then bend, straighten, rotate, or press on the knee to feel for injury and find out how well the knee moves and where the pain is.
Depending on your medical history and the findings of the physical exam, your doctor may recommend one or more of these tests to see inside your knee:
X-ray. This quick, painless test produces a 2-dimensional picture of your bones that helps find breaks and joint disease like osteoarthritis.
CT scan. It combines X-rays taken from many different angles to give a 3-dimensional view of the knee. The test shows much more detail of the bones than regular X-rays, and it can help diagnose bone problems and find breaks in bones that X-rays may not pick up.
Bone scan. This test creates images of bones on a computer screen or film. First, you’ll get a harmless radioactive material injected into your bloodstream. The material collects in the bones, particularly in abnormal areas of the bones, and shows up on a scanner.
MRI. In this test, a powerful magnet linked to a computer creates pictures of areas inside the knee. It’s useful for finding damage to soft tissue, such as muscles, ligaments, cartilage, and tendons.
Your doctor may order laboratory tests to confirm a diagnosis. For instance, an analysis of fluid taken from your knee can spot an infection, inflammation, or gout. The procedure can also help relieve pain and pressure.