What Is Subchondroplasty Bone Marrow Lesion Treatment?

Subchondroplasty is a minimally invasive procedure used to treat bone marrow lesions in the knee. It involves injecting a calcium phosphate bone substitute into the damaged area of bone. The goal is to support the weakened bone and reduce pain that has not responded to other treatments.

The procedure was developed for a specific problem: bone marrow lesions that show up on MRI but often do not heal on their own. These lesions are linked to pain and to the breakdown of cartilage in the knee joint. Subchondroplasty targets the bone itself rather than the cartilage or the joint surface.

What Is Subchondroplasty Bone Marrow Lesion Treatment?

Subchondroplasty is a surgical technique that fills bone marrow lesions with a flowable calcium phosphate cement. The cement hardens inside the bone and provides structural support to an area that has become weak and swollen.

Bone marrow lesions are areas of increased signal on MRI, typically seen on fluid-sensitive sequences. They represent a mix of bone swelling, microfracture, and altered bone remodeling. They are common in knees with osteoarthritis and are also seen after injuries such as ACL tears or meniscal damage.

The procedure is usually done arthroscopically, meaning through small incisions. The surgeon uses fluoroscopy — real-time X-ray imaging — to guide a needle into the lesion. Once in place, the cement is injected. Because the cement is designed to mimic the mineral phase of bone, it is gradually replaced by new bone over time.

This is not the same as a knee replacement or a cartilage repair procedure. It does not resurface the joint. It addresses the bone underneath the cartilage, which is increasingly recognized as a source of pain in knee osteoarthritis.

Who Is a Candidate for Subchondroplasty?

Candidates are typically adults with knee pain that has not improved with non-surgical treatment. They usually have an MRI showing a bone marrow lesion in a specific location that matches their pain.

The ideal candidate has a bone marrow lesion but relatively preserved cartilage. If the cartilage loss is severe and widespread, the procedure is less likely to help. Some surgeons also consider it for patients with early osteoarthritis who want to delay or avoid knee replacement.

It is not appropriate for everyone. The following factors generally rule out the procedure:

• Active infection in the knee
• Severe joint space narrowing on X-ray
• Inflammatory arthritis such as rheumatoid arthritis
• Poor blood flow to the leg
• Inability to undergo anesthesia or follow post-operative instructions

There is no single agreed-upon set of criteria. Different surgeons use different thresholds. Some rely heavily on MRI findings, while others also consider symptom duration and response to prior treatments. If you are considering this procedure, ask your surgeon exactly what findings on your imaging make you a candidate.

What Happens During the Procedure?

Subchondroplasty is usually performed as an outpatient procedure. Most patients receive regional or general anesthesia. The knee is cleaned and draped, and the surgeon makes small incisions.

Using fluoroscopy, the surgeon guides a cannula — a thin tube — through the bone and into the lesion. The calcium phosphate cement is then injected under low pressure. The cement fills the spaces within the damaged bone and hardens within minutes.

After injection, the surgeon may take additional images to confirm the cement is in the right place. The incisions are closed with stitches or sterile strips. The whole procedure typically takes less than an hour, though this varies depending on the number and location of lesions treated.

Some surgeons combine subchondroplasty with arthroscopy to address other problems at the same time, such as meniscal tears or loose cartilage. When combined, the procedure may take longer.

What Does Recovery Look Like?

Recovery varies. Most patients are asked to limit weight-bearing on the treated leg for a period after surgery. Some surgeons allow immediate partial weight-bearing with crutches, while others recommend a longer period of protection. There is no single standard protocol.

Physical therapy usually begins within the first few weeks. The goals are to restore range of motion, rebuild strength, and gradually return to normal walking. Full recovery may take several months. Some patients report improvement within weeks, while others take longer.

It is important to understand that this is not a quick fix. The bone needs time to incorporate the cement and remodel. Pushing too hard too soon may risk complications. Follow your surgeon’s specific instructions, as they are tailored to your case.

Does Subchondroplasty Actually Work?

The evidence for subchondroplasty is promising but not definitive. Several studies have reported significant pain relief and functional improvement in patients with bone marrow lesions. However, most of these studies are small, lack control groups, or have short follow-up periods.

Some research suggests that filling bone marrow lesions can reduce pain and improve function in the short to medium term. A few studies have shown that the procedure may delay the need for knee replacement in some patients. But these findings are not universal, and not all studies show benefit.

There is no large, randomized controlled trial that definitively proves subchondroplasty is superior to other treatments. The evidence is best described as limited but encouraging. This is not a reason to dismiss the procedure, but it is a reason to be cautious about expecting a guaranteed result.

It is also worth noting that bone marrow lesions sometimes improve on their own. Some studies have shown that lesions can shrink or resolve without intervention. This makes it difficult to know how much of the improvement after subchondroplasty is due to the procedure itself versus natural healing.

What Are the Risks and Complications?

As with any procedure, there are risks. The most commonly reported issues include pain at the injection site, swelling, and temporary increases in knee pain. These usually resolve with time and standard post-operative care.

More serious complications are rare but possible. These include infection, bleeding, nerve damage, and allergic reaction to the cement. There is also a risk that the cement could leak outside the bone, though this is uncommon with proper technique.

Another consideration is that the cement is not biodegradable in the traditional sense. It is gradually replaced by bone, but the process is not fully understood. Some patients may experience long-term effects that are not yet known.

Before undergoing subchondroplasty, discuss all risks with your surgeon. Ask about their personal complication rates and experience with the procedure. This is not a procedure that every orthopedic surgeon performs.

How Does It Compare to Other Treatments?

Subchondroplasty is one option among several for bone marrow lesions. Other approaches include:

• Non-surgical care: Physical therapy, anti-inflammatory medications, and activity modification
• Injections: Corticosteroids or hyaluronic acid into the knee joint
• Core decompression: Drilling small holes into the bone to stimulate healing
• Knee replacement: For advanced arthritis

Each option has different goals. Non-surgical care aims to manage symptoms. Injections target inflammation. Core decompression aims to improve blood flow. Subchondroplasty aims to stabilize the bone structurally.

There is no clear evidence that one approach is better than another for all patients. The choice depends on the size and location of the lesion, the condition of the cartilage, and the patient’s goals. Some patients may benefit from a combination of treatments.

If you have a bone marrow lesion and are considering subchondroplasty, ask your doctor how it compares to other options in your specific case. There is no one-size-fits-all answer.

Is Subchondroplasty Covered by Insurance?

Coverage varies by insurance plan and by diagnosis. Some plans cover subchondroplasty for specific indications, while others consider it experimental or investigational. This is because the evidence base is still developing.

Medicare and many private insurers may require prior authorization. They may also require documentation that other treatments have failed. It is important to check with your insurance company before scheduling the procedure.

If coverage is denied, you may be able to appeal. Some patients pay out of pocket. The cost can vary widely depending on your location and the facility where the procedure is performed.

What Should You Ask Your Doctor?

If you are considering subchondroplasty, ask direct questions. A good surgeon will welcome them.

• What does my MRI show, and where exactly is the bone marrow lesion?
• How much cartilage do I have left in that area?
• What are the alternatives, and how do they compare?
• How many of these procedures have you performed?
• What is your personal success rate and complication rate?
• What does recovery involve, and how long until I can return to normal activities?

Be wary of anyone who guarantees a cure or promises you will avoid knee replacement. No procedure can guarantee that. The goal is to reduce pain and improve function, but results vary.