Why a knee MRI?
X-rays show bone well. They do not show the soft tissues that cause most knee pain — the menisci, the ligaments, the cartilage, the tendons. MRI is the gold-standard imaging test for the inside of the knee because it shows all of those structures in fine detail, without radiation.
If you have had ongoing knee pain, swelling, locking, instability or a sports injury that has not settled, an MRI is normally the test that finally explains what is going on.