See if I'm a candidateDo I qualify?

Condition guide · Knee

Knee osteoarthritis, explained simply

If you've been told your knee is "bone-on-bone," here's what that actually means — and why understanding the cause points you toward the right treatment.

What osteoarthritis is

Osteoarthritis is the gradual wearing down of the smooth cartilage that cushions the ends of the bones in your knee. As that cushion thins, the bones move with less protection — which is where "bone-on-bone" comes from. But cartilage loss is only part of the story.

Why it actually hurts

Here's the part most people are never told: cartilage itself has no nerves, so cartilage wear alone doesn't fully explain your pain. Much of the pain comes from inflammation in the joint lining (the synovium). As arthritis progresses, that lining becomes inflamed and grows tiny, abnormal blood vessels — a process called neovascularity. These vessels feed ongoing inflammation and travel alongside nerve fibers, making the joint more sensitive and painful.

This matters because it explains why two people with similar-looking X-rays can have very different pain — and why treatments that target inflammation and abnormal blood flow can help even when the cartilage can't be restored.

How it progresses

  • ✔Early: occasional ache after activity; stiffness in the morning that eases as you move.
  • ✔Moderate: pain during and after everyday activities; swelling; trouble with stairs and getting up.
  • ✔Advanced: pain at rest and at night; noticeable stiffness and loss of motion; pain that shapes your day.
Femur & tibia the bones of the joint Cartilage the cushion that wears away Joint lining (synovium) where arthritis pain begins
Much of arthritis pain comes from the inflamed joint lining — not the cartilage alone. That's what embolization targets.

What this means for treatment

Because inflammation drives so much of the pain, calming that inflammation is a legitimate goal — not just replacing the joint. That's the idea behind genicular artery embolization (GAE): reduce the abnormal blood flow feeding the inflammation, without surgery. It's one of several options, and the right path depends on where you are in the disease and what you've already tried.

See non-surgical knee treatment → Compare your options →

This guide is general education, not medical advice. Your physician can explain what your specific imaging and symptoms mean for you.