BMAC: BONE MARROW ASPIRATE
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A patient-facing guide to intra-articular, subchondral, and tendon applications
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WHAT BMAC IS
Bone marrow aspirate concentrate (BMAC) is made from your own bone marrow, most often collected from the iliac
crest of the pelvis and processed at the time of treatment. The concentrate contains platelets, nucleated cells, a small
population of mesenchymal stromal cells, and a mixture of growth factors and signaling proteins. It is better described as
an autologous orthobiologic concentrate than as a simple “stem-cell injection.”
HOW BMAC MAY HELP
• Modulates inflammation: BMAC contains cytokines and cellular signals that can influence the inflammatory environment of an arthritic or injured tissue.
• Supports repair signaling: platelets and marrow-derived cells release growth factors involved in cell recruitment, matrix turnover, angiogenesis, and tissue remodeling.
• Targets more than cartilage: osteoarthritis is a whole-joint disease involving cartilage, synovium, subchondral bone, meniscus, and surrounding tissues. BMAC can be directed to the tissue thought to be driving symptoms.
• Uses autologous material: the injectate comes from the patient, reducing concerns about immune incompatibility and donor transmission.
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INTRA-ARTICULAR BMAC: INSIDE THE JOINT
Intra-articular BMAC is most commonly discussed for symptomatic osteoarthritis or focal cartilage/chondral pathology, especially when exercise, activity modification, medications, and simpler injections have not provided enough relief. Knee osteoarthritis has the largest clinical literature, although other joints may be treated in carefully selected patients.
SUBCHONDRAL BMAC: TREATING THE BONE UNDER THE CARTILAGE
Subchondral bone sits immediately beneath joint cartilage. In some patients with osteoarthritis, MRI shows bone marrow
lesions (BMLs), edema-like changes, or areas of subchondral stress that may be an important source of pain. Instead of
treating only the joint fluid space, BMAC can be delivered into a selected subchondral target under fluoroscopic or other
image guidance. Some protocols combine subchondral and intra-articular treatment during the same procedure.
• Why this matters: subchondral bone is richly innervated and participates in load transfer, cartilage support, inflammation, and osteoarthritis progression.
• Potential role: selected studies report improvement in pain and function and reduction in MRI bone marrow lesion burden after subchondral BMAC treatment.
• Precision is critical: this is not a “blind” injection. The clinician must correlate MRI findings with symptoms and place the treatment into the intended bony target while avoiding articular and neurovascular structures.
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BMAC FOR TENDINOPATHY AND SOFT-TISSUE INJURY
BMAC is also used by some orthobiologic practices for chronic or difficult tendinopathies, partial tendon injury, and enthesis problems when the tendon has not responded adequately to progressive loading and other conservative care. The biologic rationale is to deliver marrow-derived growth factors and repair-associated cells to a tissue with limited intrinsic healing capacity.
WHY BMAC QUALITY AND CLINIC QUALITY MATTER
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• Harvest expertise: a careful iliac-crest aspiration strategy aims to obtain marrow-rich material rather than mostly
peripheral blood.
• Processing: centrifugation and concentration should be performed with validated sterile equipment and a reproducible protocol.
• Product characterization: a high-quality clinic should be able to explain what its system concentrates and, when available, provide data such as total nucleated-cell count, platelet count, viability, and red-cell content.
• Image guidance: ultrasound or fluoroscopy should be used when accuracy matters, especially for subchondral targets, deeper joints, and tendon lesions.
• Diagnosis first: no orthobiologic can overcome the wrong diagnosis, severe instability, major malalignment, untreated infection, or a mechanical problem that requires surgery.
• Transparent counseling: patients should hear realistic expectations, alternatives, costs, rehabilitation requirements, and risks before treatment.
WHAT TO EXPECT
The procedure generally includes bone-marrow aspiration, same-day processing, and image-guided injection. Soreness
at the harvest site and treatment site is common for several days. A temporary inflammatory flare can occur. The
recovery plan depends on the target: joint patients usually return to gentle motion early, while tendon and subchondral
procedures may require more structured activity restrictions and progressive loading.
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RISKS AND LIMITATIONS
• Temporary pain, swelling, bruising, stiffness, and post-procedure flare.
• Bleeding, infection, vasovagal reaction, or injury to nearby structures are uncommon but possible.
• Bone-marrow harvest can cause pelvic soreness and, rarely, more significant bleeding or infection.
• Results vary; some patients improve substantially, some modestly, and some not at all. Severe end-stage arthritis may respond less predictably.
• BMAC protocols are not standardized across devices and clinics, which is another reason product quality and clinician experience matter.
SELECTED REFERENCES
These references are provided for clinical transparency and further reading. Individual treatment decisions require an in-person evaluation.
[1] Migliorini F, Pilone M, Ascani J, et al. Management of knee osteoarthritis using bone marrow aspirate concentrate: a systematic review. Br Med Bull.
2025;153(1):ldae016. doi:10.1093/bmb/ldae016.
[2] Han JH, Jung M, Chung K, 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;12(12):23259671241296555. doi:10.1177/23259671241296555.
[3] Fucaloro S, Bragg JT, Feldman MW, et al. Complication rates of bone marrow aspirate concentrate injections versus other injectable therapies for
knee osteoarthritis: a systematic review and meta-analysis. J Orthop. 2024;62:36-42. doi:10.1016/j.jor.2024.10.005.
[4] Keeling LE, Belk JW, Kraeutler MJ, et al. Bone Marrow Aspirate Concentrate for the Treatment of Knee Osteoarthritis: A Systematic Review. Am J
Sports Med. 2022;50(8):2315-2323. doi:10.1177/03635465211018837.
[5] Subchondral bone marrow aspirate concentrate injection improves clinical outcomes and reduces bone marrow lesions in knee osteoarthritis:
12-month retrospective analysis. PubMed PMID: 42135786. 2026.
[6] Does standalone/combined subchondral bone marrow-derived mesenchymal stem/stromal cell injection offer significantly better clinical benefit to
intraarticular injection in knee osteoarthritis? PubMed PMID: 41480404. 2025.
[7] Kunze KN, Eliasberg CD, Rodeo SA. Bone Marrow Aspirate and Bone Marrow Concentrate for the Treatment of Knee Osteoarthritis: Do They Work
and Are They Safe? Clin Sports Med. 2025;44(4):675-685. doi:10.1016/j.csm.2024.08.001.