A subchondral injection, also called a subarticular or intraosseous injection, places your own platelet-rich plasma or bone marrow concentrate into the bone just below the joint surface. We use it for advanced knee arthritis and for bone marrow lesions seen on MRI, usually paired with an injection into the joint itself at the same visit.
For forty years arthritis was taught as a cartilage disease. Cartilage has no nerves. It cannot hurt. The bone underneath it can. That layer of bone, the subchondral plate, carries the load, feeds the cartilage from below, and has its own nerve and blood supply. When it breaks down, the cartilage above it follows.
An injection into the joint space treats the room. A subchondral injection treats the foundation the room sits on. In advanced arthritis the foundation is often where the trouble started.
“Subchondral” means below the cartilage. The needle passes through a thin window of bone into the spongy marrow space of the tibia (shin bone) or femur (thigh bone), a short distance under the joint surface. We guide it with fluoroscopy so it reaches the damaged zone. The same procedure is called intraosseous (inside the bone) or subarticular (below the joint) in different papers. They all mean the same thing.
The material is usually PRP or bone marrow concentrate. Platelets are repair workers. Bone marrow cells are the general contractor, coordinating the repair crew already living in that bone.
A bone marrow lesion is a bright area inside the bone on fluid-sensitive MRI images. It marks bone under stress: tiny fractures in the scaffolding of the bone, swelling, and abnormal remodeling. Reviews of the subchondral bone now describe these lesions and the breakdown of the subchondral plate as changes that come before the cartilage fails, which suggests a window to act before the joint surface collapses.
If your MRI report mentions “bone marrow edema,” “subchondral edema,” “bone marrow lesion” or “subchondral insufficiency,” the bone is part of your pain. An injection that only reaches the joint fluid never touches it.
Because advanced arthritis is a whole-joint disease. The lining is inflamed, the cartilage is thin, and the bone under it is failing. Treating one layer and ignoring the others leaves the rest of the problem talking to the nerves.
The strongest evidence comes from a 2025 double-blind randomized trial in 86 patients with Kellgren-Lawrence grade III and IV knee arthritis. Every patient got the same plasma-rich-in-growth-factors injections into the joint. Half also got growth factors into the bone; half got saline into the bone. The group that got growth factors into the bone improved significantly more on nearly every measure of pain, symptoms, function and quality of life at 3, 6 and 12 months, with no serious adverse events.
A 2026 systematic review of 24 studies and 1,109 patients found that most reported meaningful gains in pain and function, that PRP and cell-based injections carried favorable safety profiles, and that they had lower rates of conversion to knee replacement than calcium phosphate fillers. Long-term cell-based data showed delayed replacement up to 15 years. See our intra-articular injection page for the joint-space half of the treatment.
Read the full grading discussion on knee osteoarthritis. The same bone-below-the-joint pain drives advanced hip arthritis, where marrow concentrate placed into the femoral head is an option; see hip arthritis treatment.
Bone is living tissue that remodels constantly, and three forces push it toward failure:
The injection repairs the foundation. Fixing the terrain keeps it from cracking again. Lifestyle and behavior are 40 to 50% of our protocol, with rehabilitation, laser therapy and metabolic optimization built in.
We prepare your PRP or bone marrow concentrate in an FDA-cleared system. The skin and the surface of the bone are numbed with local anesthetic. You stay awake, you feel pressure as the needle enters the bone, and most patients drive themselves home. Expect soreness for about 48 hours. Protect the area for the first few days and follow the rehab plan. You can’t make a carrot grow faster than it grows: bone remodels over weeks to months.
Yes. Subchondral, subarticular and intraosseous all describe an injection into the bone just beneath the joint surface.
You feel more pressure because the needle enters bone. The skin and bone surface are numbed with local anesthetic, you stay awake, and most patients drive home.
An MRI shows bone marrow lesions and helps us decide where to place the injection. We review your imaging at the consultation.
A 2026 systematic review reported lower conversion to knee replacement with PRP and cell-based subchondral injections, with cell-based data showing delays up to 15 years.
Some feel better in three weeks; others need a second or third treatment, decided by how the tissue responds.
Orthobiologics are not billed to insurance. HSA and FSA funds are generally eligible.
If your MRI shows bone marrow lesions or your knee injections wear off faster each time, treating the bone under the joint is the bridge between failed conservative care and surgery. We see patients at our office at 4477 Woodson Rd in St. Louis. Over 90% of our accepted case-study patients see significant improvement. Request our orthobiologics guide or call (314) 481-5000 and bring your MRI report.
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