For those with knee osteoarthritis, knee replacement surgery has long felt like an inevitability. A recent study published in the Journal of International Orthopaedics is challenging that assumption, showing that a precise application of stem cells can avoid total knee surgery in up to 80% of cases.
The Study
The study included 60 participants with painful bilateral knee osteoarthritis who were recommended for total knee replacement surgery.
Instead of surgery, each participant had both of their knees treated with autologous (from their own tissue) bone marrow-derived stem cells.
At random, one of their knees received stem cells intra-articularly, injected into the joint space, and their other knee received stem cells directly into the subchondral bone, the dense layer beneath the cartilage that covers the femur and tibia.
Neither the patients nor the evaluators knew which knee received which treatment, making the comparison unusually strong.
Participants were tracked over the course of 15 years to see how each knee performed.
The Results
During the first year, both methods of stem cell therapy improved knee pain. However, the differences became apparent over time.
Patients who received stem cells intra-articularly experienced their greatest pain relief around 12 months, with improvements gradually diminishing thereafter.
Patients treated through the subchondral bone continued to show sustained pain relief at the two-year mark, with significantly better knee function scores than knees receiving just the joint injections.
At the end of 15 years, 30% of the knees treated with the intra-articular stem cells successfully avoided knee surgery—but looking at the subchondral treatment group, the knees avoiding surgery jumped to 80%.
A Major Breakthrough for Knee Pain
This study is a major breakthrough.
It shows that stem cell therapy is a compelling long-term alternative to total knee replacement surgery—but more importantly, it shows that the placement of those stem cells makes a world of difference.
Using the same stem cells, simply targeting the correct structure more than doubled the duration of pain relief, and almost tripled the number of patients able to avoid surgery.
Precision Matters
These findings highlight an important point: not all stem cell procedures are created equal.
Most regenerative medicine clinics inject stem cells blindly into the knee joint. This is called an intra-articular injection, meaning the cells are placed into the fluid circulating at the surface of a joint. This kind of procedure is easy to perform, but as we now know, doesn’t generate the best results.
Targeting stem cells directly into the subchondral bone, beneath the surface of damaged cartilage, provides both longer-lasting pain relief, and longer-term healing. This requires specialized imaging, precise technique, and significant experience treating the underlying bone.
This is the kind of targeted treatment we offer at Compass Pain and Wellness.
Why It Works
Researchers have discovered that people with osteoarthritis already have increased stem cells floating in the joint fluid. In contrast, the subchondral bone has relatively few functioning stem cells despite being one of the primary sites where arthritis develops.
Instead of adding more cells where many already exist, subchondral injections target the area that’s more deficient. This stimulates a deeper level of healing, triggering structural repair at the root of the problem, beneath the surface of the bone.
MRI Scans Showed the Bone Was Actually Improving
Perhaps the most fascinating findings came from MRI imaging.
Patients receiving subchondral bone treatment showed:
- Regression of painful bone marrow lesions
- Reduced inflammation inside the joint
- Preservation of joint space
- Increased cartilage volume in some areas
- Slower progression of osteoarthritis
In contrast, knees treated with injections into the joint were more likely to continue narrowing their joint space and progressing to more advanced stages of arthritis.
These findings suggest that treating the bone beneath the cartilage may influence the disease process itself rather than simply reducing symptoms.
Osteoarthritis Is More Than “Worn-Out Cartilage”
For decades, osteoarthritis was viewed as a condition where cartilage gradually wears away until bone rubs against bone. Today we know it’s much more complex.
Osteoarthritis affects the entire joint, including:
- Cartilage
- Ligaments
- Joint lining (called the synovium)
- Synovial fluid, which lubricates the joint
- The subchondral bone, the layer of bone directly beneath the cartilage
In fact, MRI studies have shown that changes in the subchondral bone often appear early in knee osteoarthritis and improve earlier after treatment compared with cartilage damage.
Doctors frequently see bone marrow lesions—areas of stress and inflammation inside the bone—in people with knee arthritis. These lesions are strongly associated with pain and can be an early sign that osteoarthritis is progressing.
Why Avoid Total Knee Replacement
Total knee replacement involves complete removal of the knee joint—where the femur and tibia meet—and replacement with an artificial joint.
While artificial knees will never feel like your original, for some patients, knee replacement is a fantastic option that restores function when a joint is too far degenerated for other treatment options.
For most, knee replacement should be avoided when possible.
Knee replacement is a major surgery, requiring full anesthesia, 3–6 months of strenuous recovery, and often requiring complicated revision surgeries every 15–20 years.
The knee is the largest and most complex joint in the human body. Native structures like cartilage, tendons, and ligaments will never function identically in a prosthetic environment.
Complications, continued pain, and limited function lead roughly 20% of patients to report dissatisfaction with their knee replacement, and published research has found an increase in long-term mortality following knee replacement, especially in those under fifty.
If possible, maintaining original joint structures in the body, even if only delaying a joint replacement, offers the highest degree of satisfaction, pain relief, and function.
The Best Knee Treatment for Pain
Regenerative medicine has long provided an alternative to many invasive knee surgeries.
Recent advancements in our understanding of osteoarthritis as a disease affecting the entire joint—including the subchondral bone beneath the cartilage—have advanced regenerative medicine treatments to perform even better.
The available evidence suggests that delivering bone marrow-derived mesenchymal stem cells directly into the subchondral bone may provide the longest-lasting symptom relief, improved imaging findings, and the best chance at avoiding total knee replacement surgery altogether.
These findings underscore why the experience of the treating physician and the specific technique used are just as important as the stem cells themselves.
If you’re looking for a way to avoid total knee replacement, choosing a clinic such as Compass Pain and Wellness with expertise in advanced image-guided subchondral procedures is the ideal way to heal your knee pain.
Frequently Asked Questions About Knee Replacement Surgery and Stem Cell Therapy
What Is The Success Rate for Total Knee Replacement Surgery?
When the success of TKA is measured by a patient’s satisfaction with pain-relief, it falls short 20% of the time. In addition, more young patients are getting total knee replacements. There’s evidence that young patients are less satisfied with knee surgery, and in these patients the risk of having to do the surgery a second time is higher. On the opposite end of the spectrum, patients who are older than 85 may not be a good candidate for the procedure since they are more likely to experience complications. For all these reasons, less invasive solutions are needed.
What Are The Best Knee Replacement Surgery Alternatives?
If strategies such as modifying your activity level, weight loss, and anti-inflammatory medications don’t work, stem cell therapy is an effective option for healing joint pain naturally. A study published in the journal International Orthopaedics found that stem cell treatments can delay or eliminate the need for knee replacement surgery. Specifically, researchers looked at two types of stem cell therapy: 1) where the stem cells were injected into joint fluid and 2) where stem cells were injected into the bone under the cartilage known as subchondral bone.
Both types of stem cell treatments were effective at delaying or eliminating surgery. However, the subchondral bone injections were the clear winners. In the knees where the stem cells were injected into the joint fluid, 70% of the patients had to have knee surgery by an average of seven years. In the subchondral bone injections group, only 20% of the patients needed knee surgery, but only after an average of 14 years.
Is Stem Cell Therapy an Alternative to Knee Replacement?
Not always. Patients with advanced osteoarthritis may still benefit most from total knee replacement. However, regenerative medicine may offer another option for selected patients—particularly those with mild to moderate osteoarthritis who hope to postpone surgery.
The study’s authors concluded that for many patients with Kellgren-Lawrence Grade 1 through Grade 3 osteoarthritis (a commonly used X-ray grading system for arthritis severity), subchondral stem cell therapy could reasonably be considered before moving to knee replacement.
This research provides encouraging evidence that treating the bone beneath the cartilage—not just the joint space itself—may help preserve your knees for many years.
What Is Stem Cell Treatment?
Stem cells are the body’s natural repair cells. Doctors inject stem cells into knees in order to promote healing and reduce the risk of total knee replacement surgery. The type most commonly used in orthopedic regenerative medicine are called mesenchymal stem cell (MSC). These cells are found our bone marrow and other tissues and can help support healing by releasing signaling molecules that reduce inflammation and encourage tissue repair.
What Is Subchondral Bone?
Subchondral bone sits directly beneath the cartilage in a joint. It supports the cartilage, and cushions the blow during exercise such as walking, running, and jumping. It also keeps the joint healthy.
