What does bone on bone actually mean on my X-ray?

Doctors grade knee arthritis on a scale of 0 to 4, called Kellgren-Lawrence. Grade 4 is the one people call bone on bone. The space between the thigh bone and the shin bone has closed, the bone has spurs, and the ends of the bones have hardened.

Here is what the X-ray cannot tell you: how much it hurts. Cartilage has no nerves. The pain comes from the bone under the cartilage, the swollen lining of the joint, and a pad of fat behind the kneecap that acts like an inflamed gland. Plenty of grade 4 knees hurt less than grade 2 knees. So the picture decides what can be rebuilt. It does not decide how much relief is possible.

Is knee replacement my only option?

Replacement is the operation that fixes the structure. For the person who is ready for it, it is a good operation, and we will help you get there. But most people with a grade 4 knee are not choosing between a shot and a new knee this month. They are too young, or their heart or blood sugar has to settle first. Some have a weight target to hit. Some are caring for a spouse and cannot spend six weeks in rehab. Some just are not ready.

For that person, the real choice is between a treatment and another year of stronger pills. That year is not free. Pain pills and anti-inflammatories carry their own costs to the stomach, the kidneys, the heart and your sleep. Cutting that load is a real goal on its own.

Can PRP help a bone-on-bone knee?

Yes, within honest limits. In a blinded trial of grade 4 knees, patients who were unwilling or unable to have a replacement received a series of PRP injections or saline. The PRP group reached a clinically meaningful drop in pain and better function at three and six months. The saline group did not.

Bone marrow concentrate goes further in the worn knee. In a 2024 series of 37 knees at grade 3 or 4, most improved, and none went on to a replacement over four years of follow-up. A 2022 review of severe knee arthritis was more cautious. It found protocols all over the map and results that varied with them. We read that as a lesson about preparation, not a reason to quit.

Treating the bone under the cartilage

In a bone-on-bone knee, much of the pain lives in the bone just under the joint surface. That bone swells and takes load it was never built for. Orthobiologics can be placed into that bone, not just into the joint space, with X-ray guidance. We decide on that after reading your imaging.

Why does the dose matter so much?

A 2025 analysis of knee PRP trials found the improvement was clinically significant, and it rose with the platelet concentration delivered. Many clinics use a quick spin that leaves a thin product. We prepare a high platelet dose and confirm every injection with image guidance. In a knee this worn, a weak product or a missed joint wastes your only shot at a good result.

What else has to change for the injection to hold?

The injection quiets the joint. What happens next decides how long it stays quiet. The thigh muscles are the knee’s shock absorbers, and in a painful knee they shrink fast. Rebuilding them is not optional. Walking mechanics get checked too, because a limp loads the worst part of the joint.

Then there is the blood. High insulin and blood sugar keep the fat pad and the joint lining inflamed from the inside. We check that bloodwork at your visit, because a knee bathed in inflammation will flare again. For pain that still breaks through, a genicular nerve block and radiofrequency ablation can quiet the nerves of the knee without touching the joint. You are awake for all of it. We use local anesthetic, and most people drive home. Expect soreness for about two days after PRP.

Over 90% of our accepted case-study patients see significant improvement. These are practice-reported figures from our own population, not trial outcomes, and individual results vary.

What happens at the first visit for a bone-on-bone knee?

Bring every X-ray and MRI you have, and a list of what you take for the pain. We examine the knee, the hip above it and the back, because both can send pain to the knee. We look at how you stand and walk. We order bloodwork that shows how inflamed your system is. Then we lay out the options in plain terms: what each one can do at your grade, what it cannot do, and what you would be signing up for in rehab. Nothing gets injected at the first visit unless the plan is clear and you agree to it.

When should I stop waiting and get the knee replaced?

When the knee has a fixed bend you cannot straighten. When it is collapsing to one side. When you cannot walk a block or sleep a night despite a fair trial of everything above. At that point a replacement is the correct next step, and we coordinate the referral. Buying time is a goal. Buying time you do not want is not.

Frequently asked questions

Can cartilage grow back in a bone-on-bone knee?

No treatment reliably regrows a full layer of cartilage in a grade 4 knee. The goals are less pain, better function, fewer pills and more time with your own knee.

How long does PRP last in a bone-on-bone knee?

It varies. In the grade 4 trial, the benefit was measured at three and six months. Some knees hold longer. We track your pain and function, and a repeat follows your response, not a schedule.

Will PRP make a future knee replacement harder?

PRP does not change the bone the surgeon works on. Tell your surgeon the date of every injection, steroid or not, so the operation is timed around it.

Does Medicare cover PRP for a bone-on-bone knee?

Medicare and most private plans do not cover PRP. That is a budgeting decision about what a plan pays for. HSA and FSA funds can generally be used.

Am I too old for PRP?

Age alone does not rule you out. Your overall health, your blood sugar and how well the treatment can be paired with rehab matter more than the year on your license.

Is this the same as the knee pain page?

Our knee pain page covers knees at every stage. This page is for the knee whose X-ray already says bone on bone.

Related reading

• Knee pain
• Genicular nerve block
• Radiofrequency ablation
• Image-guided joint injections
• Hip arthritis
• Metabolic health and pain