Platelet-rich plasma (PRP) uses blood; bone marrow concentrate (BMAC) uses marrow

Knee studies haven’t found a clear winner

A review of twenty-seven knee studies compared results from blood and marrow treatments. People in both groups reported less soreness and better movement. No score clearly showed that BMAC worked better than PRP.

One smaller knee study did favor marrow treatment after twelve months. Its groups were uneven, so that finding is less certain. Taken together, the studies don’t prove that a harder marrow procedure brings more relief.

The amount of arthritis may affect whether either choice has much chance to help. Different offices also keep different amounts of platelets or marrow material. Studies haven’t shown which preparation is likely to work for your joint.

The name alone doesn’t tell you what the office prepares

Every office doesn’t make PRP the same way. The amount of blood drawn and the platelet level in the kept plasma can vary. Concentrated PRP means the office prepares plasma with more platelets than untreated blood.

BMAC also differs by the amount of marrow taken and the portion kept after spinning. Those details matter because the initials don’t tell you how much material reaches the joint. Ask the clinician to describe each step in ordinary words.

The useful questions concern your joint and the next day

Ask why a blood or marrow treatment is being discussed for your joint. The clinician can separate what the exam shows, what it only suggests and what is still unknown. You’ll also need the full price before deciding.

Find out whether one treatment or more is proposed. Ask when you may drive, walk farther and return to exercise. You also need to know how much soreness or swelling to expect the next day.

Sources

1. A meta-analysis of 27 Level I studies (1,042 PRP, 226 BMAC, 1,128 HA patients) found significantly better post-injection WOMAC, VAS and subjective IKDC scores for BOTH PRP and BMAC compared with hyaluronic acid - and NO significant difference between PRP and BMAC on any outcome score. This is the clearest published statement that the two most-marketed orthobiologics perform the same as each other in the knee.

   Belk JW, et al. — Patients With Knee Osteoarthritis Who Receive Platelet-Rich Plasma or Bone Marrow Aspirate Concentrate Injections Have Better Outcomes Than Patients Who Receive Hyaluronic Acid: Systematic Review and Meta-analysis.. Arthroscopy, 2023. DOI: 10.1016/j.arthro.2023.03.001.

2. In a within-patient placebo-controlled trial, 25 people with BILATERAL knee osteoarthritis received bone marrow aspirate concentrate in one knee and saline in the other, acting as their own controls. Pain scores fell significantly from baseline in BOTH knees at 1 week, 3 months and 6 months, and the relief - described by the authors as dramatic - did not differ significantly between the BMAC knee and the saline knee.

   Shapiro SA, et al. — A Prospective, Single-Blind, Placebo-Controlled Trial of Bone Marrow Aspirate Concentrate for Knee Osteoarthritis.. American Journal of Sports Medicine, 2017. DOI: 10.1177/0363546516662455.

3. The largest head-to-head trial of cell-based orthobiologics to date randomised 480 patients with KL II-IV knee OA across four arms: autologous bone marrow aspirate concentrate, autologous adipose stromal vascular fraction, allogeneic umbilical cord tissue-derived MSCs, and a corticosteroid injection control. At 12 months NONE of the three orthobiologic injections was superior to another or to the corticosteroid control on either co-primary endpoint (VAS pain, KOOS pain), and none of the four groups showed a significant change in MRI osteoarthritis score from baseline. No procedure-related serious adverse events were reported.

   Mautner K, et al. — Cell-based versus corticosteroid injections for knee pain in osteoarthritis: a randomized phase 3 trial.. Nature Medicine, 2023. DOI: 10.1038/s41591-023-02632-w.

4. A meta-analysis of 6 RCTs (860 patients, 334 receiving BMAC) found overall complication rates of 41.91% for BMAC versus 41.25% for comparator injectables (P=0.85), with knee effusion the commonest BMAC complication at 18.26%. Early and late complication rates did not differ significantly from HA, steroids, PRP, SVF, MSC or saline. The number needed to harm for BMAC relative to other injections was 152.

   Fucaloro S, et al. — Complication rates of bone marrow aspirate concentrate injections versus other injectable therapies for knee osteoarthritis: A systematic review and meta-analysis.. Journal of Orthopaedics, 2025. DOI: 10.1016/j.jor.2024.10.005.

5. RESTORE, the largest and most rigorously blinded placebo-controlled PRP trial in knee OA (n=288, participant-, injector- and assessor-blinded), gave three weekly injections of a commercial leukocyte-poor PRP or saline. At 12 months the change in knee pain was -2.1 vs -1.8 points (difference -0.4; 95% CI -0.9 to 0.2; P=.17) and the change in medial tibial cartilage volume was -1.4% vs -1.2% (difference -0.2%; P=.81). Twenty-nine of 31 prespecified secondary outcomes showed no between-group difference. The authors concluded the findings do not support the use of PRP for knee OA.

   Bennell KL, et al. — Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial.. JAMA, 2021. DOI: 10.1001/jama.2021.19415.

6. FDA states verbatim of stem cell products, stromal vascular fraction (adipose-derived cells), umbilical cord blood, Wharton's jelly, amniotic fluid and exosome products: 'None of these products have been approved for the treatment of any orthopedic condition, such as osteoarthritis, tendonitis, disc disease, tennis elbow, back pain, hip pain, knee pain, neck pain, or shoulder pain.' The only FDA-approved stem cell products in the United States are blood-forming (hematopoietic progenitor) cells derived from umbilical cord blood, approved only for disorders of blood production, and there are currently NO FDA-approved exosome products.

   U.S. Food and Drug Administration — Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes. FDA (Center for Biologics Evaluation and Research), 2020.