Bone Marrow Aspirate Concentrate (BMAC): A Doctor's Guide

What is in bone marrow aspirate concentrate?

Bone marrow is the soft tissue inside bones that makes blood cells. It also holds mesenchymal stromal cells, the cells that can give rise to bone and cartilage, but they are rare: roughly 0.001% of the nucleated cells in marrow. Concentrating the marrow raises their number several-fold, about six times in commonly used systems.

The finished concentrate contains:

Mesenchymal stem and stromal cells and other marrow cells
Platelets and growth factors, including PDGF, TGF-beta, and VEGF
Anti-inflammatory proteins such as interleukin-1 receptor antagonist

The cells appear to work mostly through the signals they release, which can calm inflammation and support the tissue's own repair. For the bigger picture on where BMAC fits among cell-based treatments, read What is stem cell therapy?

How the BMAC procedure works

BMAC is an outpatient procedure. The whole visit usually takes about two hours, and you go home the same day.

You lie face down, and the skin and bone surface over the back of the hip are numbed with local anesthetic.
A hollow needle draws marrow from the pelvic bone, often about 60 mL in published techniques.
The marrow is filtered and spun in a centrifuge, which takes about 30 minutes while you wait and yields a few milliliters of concentrate.
The treatment area is numbed and the concentrate is injected under ultrasound or fluoroscopy guidance.
You leave with activity instructions and a rehab plan.

What BMAC is used for

Knee, hip, and shoulder osteoarthritis
Focal cartilage injuries, sometimes alongside surgery
Partial tendon and ligament tears and chronic tendinopathy
Slow-healing fractures and bone problems, usually in a surgical setting
Injuries that have not responded to rehab or PRP

Knee osteoarthritis is the most studied use. Evidence for other joints and tendons is earlier and smaller.

What the evidence shows

Patients treated with BMAC usually improve. The harder question is whether they improve more than they would with a simpler injection.

A 2024 review of eight randomized trials with 937 patients found that BMAC improved knee pain and function starting about one month after injection. It edged out hyaluronic acid on pain at 6 and 12 months, but the difference was too small to be clinically meaningful, and it showed no advantage over other injections.
In a Mayo Clinic trial, 25 patients with arthritis in both knees received BMAC in one knee and saline in the other. Pain improved substantially in both knees, with no significant difference between them.
In a 2023 trial of 480 patients, BMAC, fat-derived cells, and umbilical cord cells all reduced pain at one year, and none beat a steroid injection. MRI showed no change in the joint in any group.
Across studies, patients with mild to moderate arthritis tended to do better than those with severe, bone-on-bone disease.

BMAC can ease symptoms and support healing. It does not regrow a worn-out joint, and it is no substitute for surgery when surgery is clearly the better option.

How long BMAC results last

Most randomized trials followed patients for 12 to 24 months, and one followed them for four years. Many patients reported relief throughout those periods, but long-term durability is not established. There is no agreed schedule for repeat injections, and the severity of the arthritis, body weight, strength, and rehab all affect how long the benefit holds.

Side effects and safety

Serious complications are rare. A 2024 analysis of six randomized trials found that BMAC had complication rates similar to other knee injections, including hyaluronic acid. Common side effects include:

Swelling of the treated joint, the most common, in about 18% of patients
Pain and stiffness at the injection site for a few days
Soreness and bruising at the hip where the marrow was drawn

Less common risks include bleeding, infection, injury to a nearby nerve or blood vessel, a temporary inflammatory reaction, and no improvement at all. Tell your physician about blood thinners and bleeding problems before the procedure.

Recovery after BMAC

Expect soreness at the hip and the treated area for several days. Ice and pain relievers your physician approves usually manage it. Most people return to desk work within a few days, use relative rest for the treated area at first, and then follow a graded rehab plan over the next several weeks before returning to sport.

BMAC vs. PRP

	BMAC	PRP
Source	Bone marrow from the back of the hip bone	Blood from a vein in the arm
What it contains	Stem and stromal cells, other marrow cells, platelets, and growth factors	Concentrated platelets and growth factors, with no live stem cells
Collection	A needle draw from the bone under local anesthetic	A routine blood draw
Relative cost	Roughly four times the cost of PRP on average	Lower
Insurance	Usually not covered	Usually not covered
Typical role	More advanced problems, or when PRP has not been enough	Often tried first

In head-to-head knee trials, BMAC has not clearly outperformed PRP. Read What is PRP therapy? for the other side of the comparison.

Is BMAC FDA-approved and legal?

BMAC is legal in the United States, and it is not FDA-approved to treat any condition. The FDA has not approved any stem cell product for osteoarthritis or other orthopedic problems. BMAC is offered because it uses your own marrow, minimally processed and returned in the same procedure, and federal rules treat that differently from lab-cultured or expanded cells and most donor cell products, which need FDA approval before they can be marketed for these uses.

Florida's 2025 stem cell law (Chapter 2025-185) uses the same approach: its definition of regulated cell and tissue products excludes minimally manipulated bone marrow used for the same basic function. The law sets separate conditions for physicians who use unapproved stem cell products in orthopedics, wound care, and pain management.

BMAC cost and insurance

BMAC is generally not covered by insurance or Medicare, so it is an out-of-pocket procedure. A 2024 review estimated that BMAC costs roughly four times as much as PRP on average. The price depends on:

How many joints or areas are treated
The processing system used to concentrate the marrow
Whether ultrasound or fluoroscopy guides the injection
Whether PRP is added and how many follow-up visits are included

Ask for a single, all-in quote before you commit.

Who is a good candidate?

BMAC tends to make the most sense for active people with mild to moderate arthritis or a partial tendon or ligament injury who have already tried rehab and simpler injections. It is a poor fit for severe, bone-on-bone arthritis where joint replacement is the better option, and for people with an active infection, a blood cancer, or an uncontrolled bleeding problem.

BMAC in Miami

I perform BMAC and other orthobiologic procedures in Miami, with ultrasound guidance and a rehab plan built around your sport or work. Before recommending it, I look at your diagnosis, imaging, and what you have already tried, and I will tell you plainly if PRP, rehab, or a surgical opinion is the better next step. See stem cell therapy in Miami, or book a consultation.

Frequently asked questions

What is bone marrow aspirate concentrate?

Bone marrow aspirate concentrate, or BMAC, is a small amount of your own bone marrow that has been spun in a centrifuge to concentrate its stem and stromal cells, platelets, and growth factors. It is injected into a painful joint, tendon, or ligament in the same visit. It is the most common way orthopedic physicians use a patient's own stem cells.

Is BMAC FDA-approved?

No. BMAC is not FDA-approved to treat osteoarthritis or any other orthopedic condition. Because it uses your own marrow, minimally processed and returned in the same procedure, it is regulated differently from cultured or donor stem cell products, which is why physicians can offer it.

Does a bone marrow aspiration hurt?

The skin and the surface of the bone are numbed first, and most patients describe the draw as deep pressure or a brief ache. Some trials have described the harvest as painless. Soreness at the hip for a few days afterward is common.

How long does BMAC take to work?

Improvement is gradual. In randomized trials of knee arthritis, pain scores began improving about one month after injection and continued to improve over the following months. Most physicians judge the result at around three to six months.

How long do BMAC results last?

Most randomized trials followed patients for 12 to 24 months, and one followed them for four years, with pain relief reported across those periods in many patients. Long-term durability is not established, and the ideal number and timing of repeat injections is still unknown.

Is BMAC covered by insurance?

Generally no. BMAC injections are not currently covered by most insurers or Medicare, so patients pay out of pocket. The consultation, X-rays, or MRI before a procedure may still be covered by some plans.

Is BMAC better than PRP?

Not consistently. In randomized trials of knee arthritis, BMAC did not show a clinically meaningful advantage over PRP, hyaluronic acid, or a steroid injection, and it costs more. It may still make sense for selected patients with more advanced problems or when PRP has not helped enough.