Stem Cell Therapy in Orthopedics: What the Science Says

What Is Stem Cell Therapy in Orthopedics?

Stem cell therapy refers to treatments that use stem cells — undifferentiated cells capable of self-renewal and differentiation into specialized cell types — to stimulate tissue repair and regeneration. In orthopedics, stem cell injections are used to treat cartilage damage, tendon injuries, and joint arthritis.

Stem cell therapy is sometimes called "biologics" or "regenerative medicine" and is frequently marketed alongside PRP (platelet-rich plasma) therapy. However, it's important to understand that the regulatory status, evidence base, and mechanism of action differ significantly between various "stem cell" products.

Types of "Stem Cell" Treatments

Bone Marrow Aspirate Concentrate (BMAC)

The most clinically supported autologous (your own cells) stem cell treatment:

Bone marrow is aspirated (drawn out) from the patient's posterior iliac crest (back of the pelvis)
The aspirate is concentrated by centrifugation
The concentrate contains mesenchymal stem cells (MSCs), growth factors, and platelets
Injected into the target tissue under ultrasound or fluoroscopic guidance

MSCs can potentially differentiate into cartilage cells (chondrocytes), bone cells (osteoblasts), and tendon cells.

Adipose-Derived Stem Cells (Fat-Derived)

Fat tissue (adipose) is liposuctioned from the patient
Processed to isolate the stromal vascular fraction (SVF) containing stem cells and growth factors
Requires more processing equipment and time
Reasonable clinical evidence emerging

Amniotic and Umbilical Cord Products

Processed products from amniotic fluid, membrane, or umbilical cord tissue are widely marketed as "stem cell" treatments. However:

FDA position: Most commercially available amniotic/cord products are regulated as HCT/P (human cells, tissues) and must be "minimally manipulated" — processing that would preserve viable stem cells typically requires a Biologics License Application (BLA)
The evidence problem: True viable stem cells in these commercial products are unproven; they likely function via growth factors and extracellular matrix proteins rather than living stem cells
The FDA has issued warning letters to companies making unsubstantiated claims about amniotic products

Bone Marrow Concentrate (Autologous) vs. Commercial Products

Autologous BMAC and fat-derived SVF (using your own cells processed same-day) operate under different regulatory frameworks and have more biological rationale than commercial "off-the-shelf" amniotic products.

What Conditions Have Evidence?

Knee Osteoarthritis (Most Evidence)

Multiple controlled trials and systematic reviews show that BMAC injections for knee OA:

Reduce pain and improve function at 6–12 months
May produce better outcomes than hyaluronic acid injections
Do not clearly halt or reverse cartilage loss on imaging

The evidence is more robust for mild-moderate OA than severe (bone-on-bone) disease.

Osteochondral Defects (Cartilage Defects)

BMAC combined with scaffold materials is used as part of complex cartilage repair procedures. Evidence is emerging and technique-dependent.

Tendon Injuries

Limited controlled evidence; some studies show benefit for chronic patellar tendinopathy and Achilles tendinopathy. Research is ongoing.

Other Joints (Hip, Shoulder, Ankle)

Preliminary evidence exists; insufficient high-quality trials for definitive recommendations.

What Stem Cell Therapy Is NOT (Yet)

Not a proven cure for arthritis: No treatment currently reverses end-stage cartilage loss
Not standardized: Enormous variation in processing, cell concentration, and delivery across centers
Not covered by most insurance: Consider significant out-of-pocket costs ($3,000–10,000+)
Not FDA-approved for most uses: While BMAC is used clinically within regulatory guidelines, most orthopedic stem cell applications are not FDA-approved through clinical trials

Key Questions to Ask Before Treatment

What type of stem cells are being used? (Your own BMAC vs. commercial amniotic product?)
How are cells processed, and what cell concentration is achieved?
Is ultrasound or image guidance used for injection?
What is the evidence for this treatment for my specific condition?
What does this cost, and what does insurance cover?
What are the risks of this procedure?
What is your experience with this treatment?

Be cautious of clinics making extravagant claims or charging very high fees without providing evidence-based answers to these questions.

Recommendations

Seek treatment from board-certified orthopedic surgeons or sports medicine physicians who are transparent about the evidence
Autologous (your own cells) BMAC at academic or reputable orthopedic centers has the most biological rationale
Consider PRP as a lower-cost, better-evidenced alternative for many conditions where stem cells are being considered
Participate in clinical trials if offered — advances the science for everyone