A microfragmented fat injection takes a small amount of your own fat, usually from the belly or flank, rinses it and breaks it into tiny clusters, then injects it into a worn joint or damaged tendon. In St. Louis, we do the whole procedure in one visit under local anesthetic. It cushions the joint and releases repair signals.
Fat has a bad reputation. Around the waist and the organs, it acts as an inflammatory organ that drives insulin resistance and joint pain. The fat just under the skin of the belly is different tissue with a different job. It is packed with small blood vessels and the support cells that sit along them, and those cells are some of the most active signal-makers in the body.
Microfragmented fat, often called mFat, puts that tissue to work where you need it: in a knee that has lost its cushion or a tendon that has stopped healing.
You lie comfortably while we numb a small patch of skin on the abdomen or flank. Through a tiny nick, a thin blunt cannula draws out a modest amount of fat after the area is filled with numbing fluid. You are awake the whole time, and you feel pressure and tugging more than pain. No general anesthesia, no sedation and no operating room. A 2025 report described the full sequence, from harvest to knee injection, done under local anesthetic alone with good outcomes at two years.
The fat goes into a closed, FDA-cleared device that uses mechanical action alone: saline rinses away blood and oily debris while the tissue is broken down into small clusters. No enzymes, no lab culture and no chemicals. The result keeps the tissue’s natural structure, including the tiny vessels and the cells that live along them, in a form small enough to pass through an injection needle. It is ready the same visit.
It does two jobs at once.
In six randomized trials comparing the two in knee arthritis, mFat and PRP gave comparable pain relief and function up to two years, with mFat showing a small edge at six months. A second 2025 review found no meaningful difference between mFat, PRP and bone marrow concentrate. A four-year study of early knee arthritis reported lasting gains in pain and function after a single mFat injection.
It is a weaker fit when the main pain source is in the bone under the joint; there, bone marrow concentrate and subchondral injection make more sense.
Cartilage has no blood supply of its own. It lives on the fluid in the joint and on the health of the bone beneath it. Insulin resistance floods that fluid with inflammatory signals that tell cartilage cells to stop building and start breaking down. Poor sleep raises the same signals and cuts the overnight repair window. Then load finishes the job: every extra pound of body weight multiplies across the knee with each step, and a weak thigh lets the joint take the impact the muscle should absorb.
The behavioral piece is the one nobody bills for. Long shifts, cheap calories and a commute that leaves no time to train are a system working against your knees. That is why lifestyle and behavior are 40 to 50 percent of our plan, with metabolic optimization, rehabilitation and laser therapy built around the injection. Learn where knee arthritis pain comes from.
Everything happens at our office at 4477 Woodson Rd in St. Louis. You are awake, under local anesthetic, and most patients drive themselves home. The harvest site will be bruised and tender for several days, and the treated joint will be sore. Protect the area for the first few days and follow the rehab plan. Some people feel better in three weeks; others need a second or third treatment, decided by how the tissue responds.
No. We take a small amount of fat through a tiny opening under local anesthetic. The goal is treatment material, and the amount removed will not reshape your body.
No. It is not billed to insurance. That is a payer budgeting decision. HSA and FSA funds are generally eligible.
No. Even lean patients have enough under the skin of the belly or flank for a treatment.
No. The harvest and the injection are both done under local anesthetic while you are awake.
One visit. The harvest, processing and guided injection happen back to back in our office.
In knee trials they perform about the same. The choice rests on your joint, your past response to PRP and your goals.
If your joint needs more than a short-acting fix, microfragmented fat may be the right tool. Compare all options on our orthobiologics in St. Louis page. Over 90% of our accepted case-study patients see significant improvement. These are practice-reported figures from our own population, not trial outcomes, and individual results vary. Request the free orthobiologics guide above, or call (314) 481-5000 and ask whether you are a candidate.
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