The Joint Replacement Podcast — Episode 64
What if the future of knee arthritis treatment isn’t replacing damaged joints, but preventing the damage in the first place?
Each year, hundreds of thousands of Americans undergo knee replacement surgery to relieve pain and restore mobility. Modern knee replacement is one of the most successful operations in orthopedic surgery, but what if advances in regenerative medicine could someday make it unnecessary?
That’s the ambitious vision of Dr. Marc Pietropaoli, an orthopedic sports medicine surgeon, regenerative medicine advocate, and author of Repair Not Replace.
His goal? Eliminate the need for knee replacements by 2043.
In Episode 64 of The Joint Replacement Podcast, I sat down with Dr. Pietropaoli to explore the science behind regenerative medicine, what stem cells and platelet-rich plasma can realistically accomplish, and whether we might someday reverse arthritis rather than replace the joint.
Our conversation brought together two perspectives: mine as a joint replacement surgeon and his as a surgeon focused on joint preservation.
The discussion raised some fascinating questions about where arthritis pain actually originates, what we’re currently capable of treating, and where the future of orthopedics may be headed.
Can We Actually Reverse Knee Arthritis?
This was one of the first questions I asked Dr. Pietropaoli.
Are we truly reversing knee arthritis, or are we simply developing better ways to manage the symptoms?
His answer highlights an important distinction.
We cannot currently take an arthritic knee in an 81-year-old patient and restore it to the condition of a healthy 18-year-old knee.
Despite some marketing claims, injections of stem cells or other biologic products have not been proven to reliably regenerate large areas of normal articular cartilage in patients with advanced osteoarthritis.
However, regenerative medicine researchers are investigating ways to improve the biological environment inside the joint, reduce inflammation, support tissue healing, and potentially influence the progression of arthritis.
Dr. Pietropaoli believes an important part of that process involves something many patients have never heard of: subchondral bone.
The Surprising Source of Knee Arthritis Pain
When most people think about knee osteoarthritis, they picture cartilage wearing away until the joint becomes bone-on-bone.
But here’s something surprising.
Articular cartilage itself doesn’t contain pain nerves.
That means damaged cartilage is not directly responsible for all the pain associated with arthritis.
The bone immediately underneath the cartilage, called subchondral bone, is richly innervated and can be an important source of pain.
As cartilage deteriorates, mechanical forces across the knee change. The underlying bone may experience increased stress, structural changes, inflammation, and microscopic injury.
In some patients, these changes appear on MRI as bone marrow lesions.
Dr. Pietropaoli believes these lesions may represent an important therapeutic target.
Why Bone Marrow Lesions Matter
Bone marrow lesions are areas of abnormal signal within the bone that can be associated with osteoarthritis and increased pain.
Research has linked certain bone marrow lesions with arthritis progression and a greater likelihood of eventually undergoing knee replacement.
During our discussion, Dr. Pietropaoli highlighted research suggesting that patients with these lesions may face substantially higher risks of future joint replacement.
However, an association between bone marrow lesions and disease progression does not necessarily establish that treating those lesions will prevent surgery.
That distinction is important when evaluating emerging treatments.
Still, it raises an intriguing possibility:
Could treating the underlying bone become an important part of managing knee arthritis?
PRP Injections: Are We Getting Better at Treating Arthritis?
One of the most commonly discussed regenerative treatments is platelet-rich plasma, or PRP.
PRP is created by drawing a patient’s blood and processing it to concentrate platelets, which contain growth factors and other biologically active substances.
The resulting preparation is injected into the affected tissue or joint.
Some clinical studies suggest PRP may improve pain and function in appropriately selected patients with knee osteoarthritis.
But not all PRP injections are equivalent.
Dr. Pietropaoli emphasized the importance of platelet dose, describing research investigating higher total platelet counts and how different formulations may affect outcomes.
Other variables include platelet concentration, leukocyte content, preparation method, and injection technique.
These differences make it difficult to compare studies and determine which preparation is best.
The key takeaway: PRP may provide symptom relief for certain patients, but it has not been established as a treatment that reliably regenerates cartilage or permanently reverses osteoarthritis.
Bone Marrow Aspirate Concentrate: Can We Treat Arthritis From Within the Bone?
One of the most interesting parts of our conversation involved bone marrow aspirate concentrate, commonly called BMAC.
Unlike PRP, which comes from circulating blood, BMAC is collected from the patient’s bone marrow, frequently from the pelvis.
The collected material is processed into a concentrated preparation containing a mixture of cells and biologically active components.
Although BMAC contains a small population of mesenchymal stromal cells, it is not equivalent to an injection of purified, expanded stem cells.
Dr. Pietropaoli uses BMAC as part of his regenerative medicine program.
What makes his approach particularly interesting is where he places the injections.
Injecting Into the Joint vs. Into the Bone
Most patients are familiar with injections delivered directly into the knee joint.
But Dr. Pietropaoli also performs injections into the subchondral bone, targeting areas identified on imaging.
This is called intraosseous injection.
During the episode, he discussed research by French orthopedic surgeon Philippe Hernigou investigating bone marrow concentrate injections in patients with advanced knee arthritis.
He described studies comparing intra-articular and intraosseous injections and their associations with subsequent knee replacement.
These findings are provocative, but the evidence remains insufficient to conclude that intraosseous BMAC provides outcomes equivalent or superior to total knee replacement.
Larger, independently replicated randomized trials with long-term follow-up will be important before this approach can become an established alternative to arthroplasty.
Can Patients With Bone-on-Bone Arthritis Avoid Knee Replacement?
This may be the most important question for patients considering surgery.
Dr. Pietropaoli shared his experience treating patients with advanced arthritis, including some with severe cartilage loss.
He reported that many patients participating in his regenerative medicine program experienced meaningful improvements in pain and function.
He also described clinical estimates suggesting that a substantial proportion of his patients avoided knee replacement during the available follow-up period.
These results deserve further investigation.
However, patients should understand the distinction between a treatment program’s observed outcomes and proof that the treatment itself prevented knee replacement.
Patients pursuing regenerative care may differ substantially from those choosing surgery. Decisions to undergo replacement are influenced by personal preferences, access to care, symptoms, and other factors.
Likewise, an improvement in pain does not necessarily mean the underlying arthritis has reversed.
For patients with advanced arthritis, total knee replacement remains an established treatment supported by extensive clinical evidence.
The goal is not to perform surgery simply because an X-ray shows arthritis. It is to help patients understand their options and decide when their symptoms and limitations justify an intervention.
Measuring Results: What Do Patients Actually Experience?
One area where Dr. Pietropaoli and I found common ground was the importance of patient-reported outcome measures.
In joint replacement surgery, we increasingly measure success using tools such as the Knee injury and Osteoarthritis Outcome Score (KOOS).
These questionnaires assess symptoms, pain, daily function, and quality of life.
During the interview, Dr. Pietropaoli shared registry data from patients participating in his regenerative treatment program.
He described average functional scores improving from approximately 50 at baseline to the mid-70s within several months and approximately 87 at two years.
These reported improvements are encouraging.
However, the outcomes were not presented as results from a randomized head-to-head comparison with knee replacement surgery.
Understanding how these treatments compare requires evaluating patient selection, baseline arthritis severity, meaningful clinical improvement, durability, complications, costs, and eventual conversion to surgery.
For any new orthopedic treatment, improving patient outcomes matters more than simply demonstrating an interesting biological mechanism.
Why Regenerative Medicine Isn’t Just About Injections
Another important point from our discussion was that Dr. Pietropaoli doesn’t consider regenerative medicine a single injection or procedure.
His practice combines multiple interventions, including:
- Bone marrow concentrate and PRP treatments
- Supervised strength and conditioning
- Physical therapy and movement optimization
- Nutrition and weight management
- Laser therapy
- Long-term patient education and follow-up
He emphasized the importance of treating the whole person rather than focusing exclusively on one joint.
This reflects a principle that is equally relevant to joint replacement surgery.
Patients who optimize strength, mobility, nutrition, and general health before surgery often have a better foundation for recovery.
However, comprehensive programs also create an important research challenge.
If patients improve after receiving injections, supervised exercise, nutritional interventions, and regular coaching, how much improvement can be attributed to each individual component?
Controlled clinical trials are necessary to answer that question.
What About Exosomes and Other Emerging Therapies?
We also discussed exosomes, which are small extracellular vesicles involved in communication between cells.
Exosomes have attracted considerable interest because they may carry biologically active signals involved in inflammation and tissue repair.
But promising laboratory science does not automatically translate into established clinical treatment.
Exosome products are not currently FDA-approved for treating knee osteoarthritis.
Patients should approach marketing claims about exosome injections, cartilage regeneration, and other emerging biologic therapies with appropriate skepticism.
Before paying for an experimental treatment, patients should ask whether there are published clinical trials supporting its effectiveness, what outcomes have been measured, and what is known about its safety.
The Future: Preventing Arthritis Before It Starts
Perhaps the most compelling point from our conversation was Dr. Pietropaoli’s belief that preventing osteoarthritis may be more achievable than curing established disease.
His background in sports medicine has shaped this philosophy.
For example, ACL injuries increase the long-term risk of developing post-traumatic knee osteoarthritis.
Preventing these injuries through neuromuscular training programs could reduce the number of patients who develop arthritis decades later.
He also discussed advances in ACL repair, including the BEAR procedure, and emerging technologies such as gene therapy, tissue engineering, and biologic scaffolds.
Whether these innovations will eventually reduce the need for knee replacement remains to be seen.
But the broader philosophy is compelling.
If we can prevent joint damage, identify progressive disease earlier, and develop treatments that meaningfully alter its course, we may be able to reduce the burden of arthritis before patients ever need surgery.
My Perspective as a Joint Replacement Surgeon
As someone who performs hip and knee replacement surgery, I find these discussions particularly valuable.
Modern total knee replacement can provide substantial pain relief and functional improvement for patients with advanced arthritis.
But that doesn’t mean our objective should be to perform as many replacements as possible.
The best outcome is the one that gives each patient durable pain relief, improved mobility, and a better quality of life.
For some patients, that means physical therapy, exercise, weight management, medications, or injections.
For others, particularly those with advanced arthritis and persistent limitations despite appropriate nonsurgical treatment, joint replacement may offer the most predictable path forward.
And perhaps someday, advances in regenerative medicine will allow us to repair or prevent the joint damage that currently leads patients to surgery.
Dr. Pietropaoli’s goal of eliminating knee replacements by 2043 is ambitious and remains speculative.
But challenging established assumptions and rigorously evaluating new treatments are essential parts of medical progress.
The key is balancing innovation with scientific evidence, transparency, and realistic expectations for patients.
Listen to Episode 64 of The Joint Replacement Podcast
Can We End Knee Replacements by 2043? | Dr. Marc Pietropaoli
In this episode, we discuss the science and controversies surrounding regenerative treatments for knee osteoarthritis, including PRP, bone marrow concentrate, subchondral bone, cartilage regeneration, and the future of joint preservation.
Listen or watch on:
- YouTube: @thejointreplacementpodcast
- Spotify
- Apple Podcasts
- The Joint Replacement Podcast
About our guest: Dr. Marc Pietropaoli is an orthopedic sports medicine surgeon, regenerative medicine advocate, founder of Victory In Motion, and author of Repair Not Replace.
Learn more: Victory In Motion
About the host: Dr. Matthew Sloan is a board-certified, fellowship-trained orthopedic surgeon specializing in hip and knee replacement, including robotic-assisted joint replacement. He hosts The Joint Replacement Podcast, helping patients better understand their treatment options and the surgeons who perform them.
Learn more: MatthewSloanMD.com
Medical disclaimer: This article and podcast are for educational purposes only and do not constitute personalized medical advice. Treatment decisions should be made with a qualified healthcare professional after reviewing your individual diagnosis, imaging, symptoms, and medical history. Statements concerning emerging regenerative treatments reflect the discussion and should not be interpreted as proof of clinical effectiveness or regulatory approval.