This page is for general educational purposes and does not provide medical advice, diagnosis, or a treatment recommendation.
Bone Marrow Aspirate Concentrate (BMAC): What It Is and What the Evidence Shows
Bone marrow aspirate concentrate, commonly called BMAC, is an orthobiologic injection made from a patient’s own bone marrow. Physicians most often use it for selected orthopedic problems, particularly knee osteoarthritis and certain cartilage, tendon, or bone injuries. Studies report that some patients improve after BMAC, but randomized trials have not consistently shown that it works better than PRP, other injections, or placebo.
BMAC is not the same as a laboratory-expanded stem-cell product. It contains a mixture of platelets, white blood cells, growth factors, and a relatively small number of mesenchymal stromal cells. The exact composition varies with the patient, collection technique, processing system, and injection protocol.
How BMAC Is Prepared
A clinician removes bone marrow through a needle, usually from the back of the pelvis. Local anesthetic and, in some practices, sedation may be used. The marrow is then processed in a centrifuge or concentration system, and the resulting preparation is injected into the treatment area. Ultrasound or fluoroscopic guidance may be used to help place the injection accurately.
The aspiration and injection are commonly performed during one outpatient visit. BMAC may be used by itself or alongside surgery, PRP, rehabilitation, or another treatment, which can make study results difficult to compare.
What Is BMAC Used For?
BMAC is most frequently studied for knee osteoarthritis and focal cartilage injuries. It is also offered for selected hip, shoulder, tendon, bone-healing, and sports-medicine concerns. A provider should explain the evidence for the patient’s exact diagnosis rather than applying results from knee studies to a different joint or condition.
What Does the Evidence Show?
Knee osteoarthritis: Recent systematic reviews of randomized trials report improvements in pain and patient-reported function after BMAC injections. However, comparative trials have not consistently shown that BMAC is superior to PRP, other biologic injections, or placebo. Differences in preparation, cell counts, disease severity, and follow-up also limit firm conclusions.
Other orthopedic uses: Evidence for hip osteoarthritis, cartilage defects, tendon problems, and bone healing is less mature. Early studies may be encouraging, but many are small, nonrandomized, or combine BMAC with surgery or another procedure. Longer-term comparative trials are still needed.
BMAC should not be described as a proven way to regrow an entire joint, reverse advanced arthritis, or reliably prevent surgery. Improvement, when it occurs, may reflect reduced symptoms or better function rather than complete tissue restoration.
Regulatory Considerations
In the United States, a device may be cleared to collect or concentrate bone marrow without the FDA approving BMAC as a treatment for a particular disease. Device clearance and treatment approval are different. Ask the provider what system is used, how the marrow is processed, and whether the proposed use complies with current federal and state requirements.
What to Expect
Temporary soreness can occur at both the marrow-collection site and the injection site. Bruising, swelling, and stiffness are also possible. A clinician may recommend short-term activity modification followed by progressive rehabilitation. Recovery and the number of treatments vary by diagnosis and procedure.
Risks and Limitations
Potential risks include pain, bleeding, infection, nerve or tissue injury, reaction to medications used during the procedure, and failure to improve. Bone-marrow aspiration adds discomfort and procedural risk that is not present with a simple blood draw. Patients should discuss blood disorders, active infection, cancer-related considerations, anticoagulant use, anemia, and other relevant medical conditions with the treating clinician.
BMAC is often not covered by insurance. Ask for the complete cost, including imaging, facility charges, sedation, rehabilitation, and follow-up care.
Questions to Ask a BMAC Provider
- What is my exact diagnosis, and how was it confirmed?
- What evidence supports BMAC for this diagnosis and stage of disease?
- What alternatives should I consider, including rehabilitation, medication, PRP, or surgery?
- Where will the marrow be collected, and who performs the aspiration?
- How is the BMAC processed, characterized, and injected?
- Will image guidance be used?
- What outcome is realistic, and how will success be measured?
- What are the risks, recovery plan, and total cost?
Sources and Further Reading
- Han JH, et al. Bone Marrow Aspirate Concentrate Injections for the Treatment of Knee Osteoarthritis: A Systematic Review of Randomized Controlled Trials. Orthop J Sports Med. 2024. PMID: 39640186.
- Keeling LE, et al. Bone Marrow Aspirate Concentrate for the Treatment of Knee Osteoarthritis: A Systematic Review. Am J Sports Med. 2022. PMID: 34236913.
- Fucaloro S, et al. Complication Rates of Bone Marrow Aspirate Concentrate Injections Versus Other Injectable Therapies for Knee Osteoarthritis. J Orthop. 2024. PMID: 39473874.
- Chandrashekar S, et al. Safety and Efficacy of Bone-Marrow Aspirate Concentrate in Hip Osteoarthritis. Indian J Orthop. 2024. PMID: 38948376.
- U.S. Food and Drug Administration. Regenerative Medicine 101: Information for Patients, Caregivers and Advocates.