Regenerative medicine is a rapidly evolving field, but there are many misconceptions about what these treatments can and cannot do. One common misunderstanding is that stem-cell injections can regrow cartilage or meniscus tissue. Current scientific evidence does not support that claim.
Dr. Gomoll has studied regenerative medicine through both laboratory research and clinical trials. While regenerative treatments have not been shown to regenerate cartilage or meniscal tissue, research suggests they may help improve pain and function in selected patients.
We currently offer platelet-rich plasma (PRP) injections. Investigational stem-cell treatments are available only through approved clinical trials.
What is regenerative medicine in orthopedics?
Regenerative medicine is a category of treatments that uses the body's own cells, growth factors, and other biologic substances to support healing and improve symptoms. In orthopedics, the most common treatments include platelet-rich plasma (PRP) injections and various forms of stem-cell therapy.
Examples of stem-cell treatments include bone marrow concentrate, adipose-derived cells, amniotic fluid products, and umbilical cord blood mesenchymal stem cells. Peptide-based therapies have also gained attention in recent years, although their use in orthopedics remains largely unproven and continues to be studied.
Who is a candidate?
Candidates for PRP typically have:
- Symptomatic osteoarthritis of the knee, shoulder, or other large joint
- Pain that has not responded adequately to NSAIDs, physical therapy, or activity modification
- A desire to delay or avoid surgery, or to bridge the gap before a planned procedure
- No active infection, hematologic disorder, or contraindication to platelet-driven inflammation
Patients with a focal cartilage defect (rather than diffuse arthritis) may be better served by cartilage repair surgery. Patients with bone-on-bone arthritis may need partial or total knee replacement. Investigational stem-cell therapy is available only through our active clinical trials.
Platelet-rich plasma (PRP)
PRP is currently the only regenerative-medicine injection offered by Dr. Gomoll outside of clinical trials. It is prepared in the office on the day of treatment:
Blood draw
Routine blood draw from the patient's arm (typically 30–60 mL).
Centrifugation
Centrifugation to separate the platelet-rich plasma from red blood cells.
Guided injection
Sterile injection of the PRP into the affected joint, often under ultrasound guidance.
Platelets contain anti-inflammatory cytokines and growth factors (PDGF, TGF-β, VEGF, IGF-1) that can improve symptoms in osteoarthritis. Multiple randomized trials have demonstrated PRP superiority over gel (hyaluronan) injections for symptomatic knee osteoarthritis.
PRP vs. gel injections vs. commercial "stem cell" injections
None of these injections regrow cartilage — but they are not equivalent, and being clear about what each can and cannot do is the most important part of choosing one. This table compares the options patients ask about most for osteoarthritis pain.
| Injection | What it is | What the evidence supports | Regrows cartilage? | Coverage |
|---|---|---|---|---|
| Platelet-rich plasma (PRP) | Concentrated platelets from your own blood, delivering anti-inflammatory cytokines and growth factors | Improves pain and function in knee osteoarthritis; studies show superiority over gel (hyaluronan) injections | No | Generally cash-pay (not covered) |
| Hyaluronic acid ("gel") injection | A lubricating viscosupplement injected into the joint | Can relieve symptoms for some patients; generally outperformed by PRP in comparative knee-OA studies | No | Often covered for knee OA (varies by plan) |
| Off-the-shelf commercial "stem cell" injection | Marketed cell products sold by some commercial clinics outside of regulated trials | The claim that these regenerate cartilage or meniscus is not supported by current evidence | No | Currently there are no FDA-approved stem-cell injections available in the US for joint injections. Dr. Gomoll does not offer them outside of clinical trials. The expectation is that the recent trials will lead to official approval and commercial availability soon. |
| Investigational cell / biologic therapy (clinical trial) | True cartilage cell and biologic-implant therapies studied under FDA supervision (e.g. HYALEX, Cartistem, ReNu) | Under active investigation; outcomes are being formally studied and are not yet established | Being studied — not established | Through the clinical trial |
The honest bottom line: PRP can be a genuinely useful tool to improve osteoarthritis pain and function and to delay or bridge toward surgery — but it does not rebuild lost cartilage. Treatments that claim to regrow tissue belong in regulated clinical trials, not in cash-pay marketing.
Investigational stem-cell trials
True stem-cell and biologic-implant therapies for cartilage are available only through FDA-supervised clinical trials. Dr. Gomoll has investigated several:
- Hyalex EFS — currently enrolling. The HYALEX® Knee Cartilage System for replacement of femoral condyle cartilage and bone defects. See trial details or request a consultation to ask about eligibility
- ReNu™ (amniotic fluid stem cells) — randomized trial completed; expected to become available again in the future
- Cartistem® (umbilical-cord blood mesenchymal stem cells) — Phase I/IIa trial completed. Phase III trial starting in 2026
- Atlas Knee System — closed to enrollment, in follow-up
- NUsurface® / VENUS (artificial meniscus) — closed to enrollment, in follow-up
Dr. Gomoll's perspective on regenerative medicine
Dr. Gomoll's view of regenerative medicine is grounded in his own research rather than in marketing. As former Director of the Orthopedic Program in Brigham & Women's Center for Regenerative Medicine and a current investigator on FDA-supervised cartilage cell-therapy trials, he has studied these treatments both in the basic-science laboratory and through clinical trials. That work established a clear distinction: while these therapies do not regenerate cartilage or meniscus, pain and function can be meaningfully improved — a real benefit, but a different one than is often advertised.
For that reason, the practice offers PRP as an evidence-supported option for osteoarthritis symptoms, declines to sell off-the-shelf "stem cell" injections that promise tissue regrowth, and reserves true cell and biologic therapies for regulated clinical trials where outcomes are formally studied. Patients are given a straightforward account of what an injection can and cannot do before deciding.
Preparing for an injection
For PRP, avoid NSAIDs (Advil, Aleve, aspirin) for 7 days before the injection — anti-inflammatories can blunt the platelet response. Continue all other medications unless otherwise instructed. Eat normally. Plan a quiet day after the injection — no impact exercise. See our before-surgery checklist for general medication-stop guidance (most pre-op rules apply to surgical procedures, not in-office injections).
Materials & technology we use
- FDA-cleared PRP centrifuge systems — for consistent platelet concentration
- Ultrasound guidance — for accurate intra-articular needle placement
- Sterile single-use injection kits
- Investigational implants and cells — HYALEX, Cartistem, ReNu, Atlas, NUsurface (clinical trial only — see trials page)
What to know & the limits of injection therapy
PRP is an in-office injection, not a surgical procedure, and is generally well tolerated — but it is not without considerations. As with any joint injection, you may experience temporary injection-site pain or a flare of soreness and swelling for a day or two, and there is a small risk of infection at the injection site. Most importantly, response varies and is not guaranteed: PRP improves symptoms for many patients with osteoarthritis, but it does not rebuild cartilage, and some patients see little benefit.
Regenerative-medicine injections are not a cure for arthritis and are not a substitute for surgery when surgery is indicated. PRP is designed to relieve pain and improve function — not to regrow tissue — and results depend on the severity of the arthritis, the joint treated, and individual factors. Dr. Gomoll will review realistic expectations and whether an injection, a clinical trial, or another treatment best fits your joint.
Follow-up & outcomes
Patients can walk and resume daily activities the same day after PRP. Avoid impact exercise and NSAIDs for 1 week to allow the platelet-driven response to develop. Symptom improvement typically appears over 2–6 weeks and may continue for several months. A repeat injection at 3–6 months may be considered based on response.
If you have not had adequate relief from PRP, surgical options may be appropriate — see cartilage repair, meniscal procedures, or arthritis surgery.
Frequently asked questions
Can stem-cell injections regrow cartilage or meniscus?
Outside of FDA-supervised clinical trials, no — and that is the most important point on this page. The common claim that off-the-shelf stem-cell injections regenerate cartilage or meniscus is not supported by current scientific evidence. This claim is often promoted by commercial 'stem cell clinics' to justify high cash-pay charges (insurance does not cover these treatments). Dr. Gomoll has investigated regenerative medicine extensively in both the basic-science lab and through clinical trials.
What benefit does PRP actually provide?
Platelets contain anti-inflammatory and growth factors that can meaningfully improve pain and function in osteoarthritis. Multiple studies have shown PRP outperforms gel (hyaluronan) injections for symptomatic knee osteoarthritis. PRP does not regrow cartilage, but it can improve symptoms — a real, evidence-supported benefit.
How is PRP prepared?
PRP is prepared in the office on the day of treatment. We perform a routine blood draw from your arm, then place the blood in a centrifuge that separates the platelet-rich plasma from red blood cells. The platelet-rich layer is drawn off and injected into the affected joint under sterile conditions, often with ultrasound guidance.
Are stem-cell trials available?
Yes. Dr. Gomoll has run FDA-supervised clinical trials of umbilical-cord mesenchymal stem cells (Cartistem®) and amniotic-fluid injections (ReNu™). A new Cartistem trial is starting up — see our active clinical trials page for participation details and contact information.
How much do PRP injections cost?
PRP is generally not covered by insurance and is offered as a cash-pay service. The price covers the blood draw, centrifugation, and ultrasound-guided injection. Contact our office for current pricing. Investigational stem-cell and biologic therapies are provided only through clinical trials, which have their own enrollment and cost considerations.
Am I a candidate for PRP?
PRP is most often used for symptomatic osteoarthritis of the knee, shoulder, or another large joint that has not responded adequately to NSAIDs, physical therapy, or activity modification, in patients without active infection or a hematologic disorder. Patients with a focal cartilage defect rather than diffuse arthritis may be better served by cartilage repair, and patients with bone-on-bone arthritis may need partial or total knee replacement. Dr. Gomoll will help determine which path fits your joint.
Is PRP a surgery? What is recovery like?
No — PRP is an in-office injection, not a surgical procedure. There is no anesthesia, incision, or operating room. The visit takes about 30–45 minutes; you can walk and resume normal daily activities the same day. Avoid impact activity and NSAIDs for about a week so the platelet-driven response can develop, with symptom improvement typically appearing over 2–6 weeks.
Dr. Gomoll offers PRP and runs FDA-supervised regenerative-medicine clinical trials at the Hospital for Special Surgery, 523 East 72nd Street on Manhattan's Upper East Side, caring for patients from across New York City, the tri-state area, and beyond who want an honest, evidence-based answer about what regenerative medicine can do for their joint. See our location and directions or request an appointment.
Medical disclaimer
This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Orthopedic care should always be discussed with a board-certified orthopedic surgeon who has reviewed your imaging, history, and physical examination. Individual outcomes vary based on diagnosis, anatomy, comorbidities, and other factors. Investigational therapies are available only through regulated clinical trials.