PRP, Bone Marrow, or Wharton’s Jelly for Knee Pain?

By Marc Darrow, MD, JD

Before considering an injection for knee pain, I want the patient to understand two things: what is causing the pain and what the proposed preparation actually contains. The label “stem cell treatment” does not answer either question.

PRP comes from a patient’s blood. Bone marrow aspirate concentrate comes from marrow and contains a mixture of cells and other components. Wharton’s jelly is connective tissue from a donor umbilical cord. These sources differ, and the evidence for one cannot simply be transferred to another.

For someone with knee arthritis or a meniscus-related problem, the useful question is not which preparation sounds most regenerative. It is which treatment has evidence relevant to that knee, what improvement is realistic, and what additional procedure or uncertainty comes with it.

Understanding the sources

Cord blood is blood collected from the cord; Wharton’s jelly is its connective tissue. They should not be used as interchangeable names.

Does marrow outperform PRP for knee arthritis?

A randomized trial of 90 patients with mild-to-moderate knee osteoarthritis compared a single marrow-concentrate injection with PRP. Both groups improved, with no significant difference between groups through two years. Attrition at later follow-up limits certainty. (1)

When discussing these options, I would not assume marrow must work better simply because it contains cells. It does not prove equivalence between every PRP system, every marrow protocol, and donor cord products. It also did not establish cartilage regeneration.

Where does hyaluronic acid fit?

Hyaluronic acid is a component of normal joint fluid. Injectable hyaluronic acid products, also called viscosupplements, are manufactured preparations intended to help osteoarthritis symptoms. They are different from PRP, marrow concentrate, and donor cord tissue. An injection of hyaluronic acid does not contain a patient’s platelets or marrow cells.

A large 2022 systematic review identified 169 trials. Its main pain analysis, using 24 large placebo-controlled trials, found an average benefit smaller than the review’s threshold for a clinically important difference. It also found an association with more serious adverse events; that does not establish that each reported event was caused by an injection. (7)

This helps explain why recommendations about viscosupplementation differ and why an individual treatment decision needs a discussion of likely benefit and risks. It does not justify describing joint replacement as inevitable for every patient who receives these injections.

Likewise, reports that people receiving hyaluronic acid underwent replacement later cannot, by themselves, prove that the injections caused the delay. Patients differ in disease severity, preferences, access to surgery, and other treatment. A longer interval before surgery is a different outcome from cartilage regeneration.

Laboratory research about cells influencing hyaluronic acid production is interesting. It does not establish that a same-day marrow or cord-tissue injection restores normal lubrication or reverses arthritis in a person. I would judge a proposed treatment by its clinical evidence rather than by that proposed mechanism alone.

What if the main concern is a meniscus tear?

Knee osteoarthritis and a symptomatic meniscal tear are different research questions, even when they coexist.

A 2024 systematic review of nonsurgical PRP treatment for meniscus tears included six studies and 184 patients. Clinical and MRI findings varied, and most studies were uncontrolled. Complete healing on MRI ranged from none to 44% in the studies reporting it. The authors stressed heterogeneity and the limited comparative evidence. (2)

An improvement in knee pain therefore should not be described as guaranteed meniscus repair. The site’s meniscus research article discusses this separate clinical question; findings from laboratory work or a different cell product need their own interpretation. A locked knee, an acute displaced tear, or another significant mechanical problem warrants orthopedic assessment rather than assuming an injection can address it.

How strong is Wharton’s jelly evidence?

There are preliminary reports using non-expanded cord-tissue preparations. For example, a published Wharton’s jelly knee-arthritis report describes one patient’s course after treatment. A case report can suggest a question for research; it cannot establish comparative effectiveness or show that the preparation works as well as marrow. (3)

A trial protocol is also different from a completed outcome study. The existence of registered research is not proof of success. Evidence using culture-expanded cord-derived cells has been excluded from this article, as it cannot establish the effectiveness of a different non-expanded tissue product.

FDA guidance identifies Wharton’s jelly and other regenerative products among therapies that may require investigational oversight and approval, and states that such regenerative therapies have not been approved for orthopedic conditions. (4)

Collection, same-day use, storage, and multiple areas

Marrow aspiration is invasive. Local anesthetic may reduce discomfort, but pressure, pain, bruising, bleeding, and infection are possible. A precise experience or collection time should not be promised for every patient.

Same-day concentration separates components; it does not mean that cells have been grown. Storage raises additional questions about validated processing, viability, intended future use, and clinical evidence. Banking a sample does not establish that it will later provide an effective orthopedic treatment.

Similarly, treating several areas requires a diagnosis and suitable plan for each site. A sample’s volume alone does not demonstrate that it provides an effective dose for every joint. Product transparency and diagnosis-specific evidence are more useful than an assurance that all sources work equally well.

Is a fat-based preparation a stronger alternative?

Microfragmented adipose tissue is another non-expanded preparation investigated for knee osteoarthritis. It contains tissue components and cells rather than a purified population grown in a laboratory.

A 2025 meta-analysis of five comparative studies found no significant advantage over the other orthobiologics studied in pain or knee scores at three, six, or twelve months. The certainty of evidence was low, with methodological limitations. This does not prove that all products are equivalent, but it challenges the assumption that a more invasive harvest necessarily provides better outcomes. (5)

It also does not establish meniscus repair. The diagnosis and outcome being studied remain important even when the preparation contains cells.

Protocols, case reports, and outcome trials are different kinds of evidence

A 2021 publication describes a protocol comparing cord-derived tissue with hyaluronic acid and saline. The protocol describes a planned study; it does not report the completed comparative outcomes. (6)

This distinction can be difficult for patients because both kinds of paper use the language of research. A planned trial may describe how investigators will measure pain, function, and imaging. Until outcomes are available, it cannot show that the proposed treatment succeeded.

The case report cited earlier is an outcome report, but it describes only one patient without a control group. It cannot determine which preparation is more effective. The marrow-versus-PRP randomized trial is a stronger comparison, but its findings apply to the studied knee-arthritis population and preparations.

The painful knee may have more than one problem

An MRI-reported meniscus tear, arthritis, swelling, and pain around a tendon attachment can coexist. They should not all be assumed to require the same injection.

A degenerative meniscal finding may be one part of a broader arthritic knee. An acute displaced tear with locking presents a different problem. The examination and imaging should help determine whether the symptoms are mainly joint-related, mechanical, or arising from another structure.

This is why an injection comparison should begin after the clinical question has been defined. Asking which source is best before deciding what is being treated can produce an impressive-sounding answer that is not useful to the patient.

More cells, more volume, and more treatments do not guarantee more benefit

The composition of a marrow sample can vary. Concentration changes its components, but the word “concentrate” does not establish a standardized viable stromal-cell dose. PRP systems also produce different preparations.

Similarly, a cord-tissue label does not establish the number or activity of viable cells after processing and storage. Tissue, isolated cells, and culture-expanded cells should not be grouped as one intervention. A study must match the actual product being proposed.

Multiple injection sessions also need their own rationale. Improvement after a series does not prove that the final injection was responsible or that repeating the series will reproduce the result. Treatment should be judged by meaningful changes in pain and function, with reassessment when progress is limited.

Knee care continues beyond the injection

The goal for an arthritic or meniscus-related knee may be comfortable walking, stairs, improved sleep, or a return to exercise. These outcomes should be distinguished from a promise of cartilage or meniscus regeneration.

Strength, mobility, appropriate activity, and management of relevant medical conditions remain part of care. A reduction in symptoms may make these activities easier, but an injection does not automatically correct alignment, instability, or a major mechanical problem.

A sudden swollen or hot joint, inability to bear weight, or true locking needs assessment. Those symptoms should not be treated as an ordinary delay in a regenerative healing process.

What I would want you to ask before treatment

Ask for the exact preparation name and source, what processing is performed, and where it will be injected. “Stem cells” is too broad a description to make an informed decision. For a donor-derived product, ask what is known about its composition after processing and storage and what human evidence supports the proposed use.

Ask whether the evidence concerns osteoarthritis, an isolated meniscus tear, or a different condition. A study of injections given during surgery does not necessarily answer the question of a nonsurgical injection. Nor does research using cells grown in a laboratory establish the effectiveness of a same-day tissue preparation.

For marrow collection, discuss discomfort, the harvesting procedure, and its additional risks. Avoiding collection may be a preference, but that does not establish that a donor product works equally well. An injection without harvesting still has risks, including pain, infection, bleeding, and a possible lack of benefit.

Agree on a practical goal: easier stairs, longer walks, less pain during sleep, or improved participation in rehabilitation. Ask when the result will be reassessed and what the next step will be if it does not help. More injections should have a reason, rather than becoming an automatic response to ongoing symptoms.

The broader guide to PRP, stem-cell preparations, and exosomes addresses similar questions across joints and tendons. For knee-specific background, see Stem Cell Therapy for Knee Osteoarthritis. Those discussions should remain diagnosis-specific; findings from one product or injury cannot establish results for another.

PRP, marrow concentrate, fat preparations, and Wharton’s jelly should not be presented as interchangeable. There is clinical research supporting symptom improvement with some preparations in selected knee conditions. That is different from proving that every injection rebuilds cartilage, repairs a torn meniscus, or prevents future surgery. Understanding what is being injected is the first step toward a useful treatment decision.

References

1. Anz AW, Plummer HA, Cohen A, Everts PA, Andrews JR, Hackel JG. Bone Marrow Aspirate Concentrate Is Equivalent to Platelet-Rich Plasma for the Treatment of Knee Osteoarthritis at 2 Years: A Prospective Randomized Trial.. Am J Sports Med. 2022;50(3):618-629. doi:10.1177/03635465211072554.
2. Gopinatth V, Batra AK, Chahla J, Smith MV, Matava MJ, Brophy RH, Knapik DM. Degenerative Meniscus Tears Treated Nonoperatively With Platelet-Rich Plasma Yield Variable Clinical and Imaging Outcomes: A Systematic Review.. Arthrosc Sports Med Rehabil. 2024;6(2):100916. doi:10.1016/j.asmr.2024.100916.
3. Gupta A, Rodriguez HC, Potty AG, Levy HJ, El-Amin SF III. Treatment of Knee Osteoarthritis with Intraarticular Umbilical Cord-Derived Wharton’s Jelly: A Case Report.. Pharmaceuticals (Basel). 2021;14(9):883. doi:10.3390/ph14090883.
4. U.S. Food and Drug Administration. Important Patient and Consumer Information About Regenerative Medicine Therapies.. FDA consumer guidance. Accessed October 12, 2026.
5. Hohmann E, Keough N, Frank RM, Rodeo SA. Microfragmented Adipose Tissue Has No Advantage Over Platelet-Rich Plasma and Bone Marrow Aspirate Injections for Symptomatic Knee Osteoarthritis: A Systematic Review and Meta-analysis. Am J Sports Med. 2025;53(4):988-998. doi:10.1177/03635465241249940.
6. Gupta A, Maffulli N, Rodriguez HC, Carson EW, Bascharon RA, Delfino K, Levy HJ, El-Amin SF. Safety and efficacy of umbilical cord-derived Wharton’s jelly compared to hyaluronic acid and saline for knee osteoarthritis: study protocol for a randomized, controlled, single-blind, multi-center trial. J Orthop Surg Res. 2021;16(1):352. doi:10.1186/s13018-021-02475-6.
7. Pereira TV, Jüni P, Saadat P, Xing D, Yao L, Bobos P, Agarwal A, Hincapié CA, da Costa BR. Viscosupplementation for knee osteoarthritis: systematic review and meta-analysis. BMJ. 2022;378:e069722. doi:10.1136/bmj-2022-069722.

10. de Sousa EB, dos Santos Junior GC, Aguiar RP, da Costa Sartore R, de Oliveira AC, Almeida FC, Neto VM, Aguiar DP. Osteoarthritic synovial fluid modulates cell phenotype and metabolic behavior in vitro. Stem cells international. 2019;2019(1):8169172.

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