A surgery that relocates tissue
Fat grafting is, as the name says, a surgery that moves fat. Fat is harvested from an area where there is a surplus and placed where there is a shortage.
The biggest distinction is that it uses your own tissue rather than introducing a foreign material the way a filler does. The burden of immune rejection is low, and once the fat settles it simply becomes your own tissue.
Still, relocating fat is not just a change of position. Fat cells are living cells too, so they need a supply of oxygen and nutrients. In their original location the blood vessels were already connected, but in the new location that connection has to be built from scratch.
This is where the outcome of fat grafting is decided. The conditions that keep the fat alive after transfer, more than the technique of transferring it, determine the result.
What is graft retention?
When transferred fat settles into its new location and survives, we call it retention. The proportion that survives is the retention rate.
Immediately after grafting, the fat cells have no blood supply. They hold out for several days on the fluid seeping in from the surrounding tissue. If new vessels grow in and connect during that window, those cells survive. If the connection comes too late, they die and are absorbed.
So retention is decided not at the moment of placement but over the following days to weeks. This is also why the area that looked full right after surgery gets smaller over time.
Reported retention rates cover a wide range. Follow-up studies show large variation depending on the area and the method. It is not a figure that can be pinned to a single number, and individual variation is considerable.
Why large amounts are not placed at once
It seems that placing more would leave more behind, but the opposite is true. If fat is packed into one spot as a mass, blood vessels cannot reach the center of that mass.
Vessels grow inward from the outside. The larger the mass, the longer its center has to hold out without oxygen, and eventually that part dies. Dead fat is either absorbed or left behind as a firm nodule, and over time it can harden into calcification.
That is why fat grafting is placed in small divided portions. When it is scattered as small particles across multiple layers, each particle has a wider surface in contact with the surrounding tissue, which opens more paths for vessels to grow in.
This is the same reason TheLINE Plastic Surgery Clinic uses dedicated micro-grafting syringes to divide each placement into small amounts and scatter them like grains of rice. It takes more time, but it is a choice made to avoid forming a mass.
Conditions that determine the retention rate
The first is the harvesting process. Fat cells are more fragile than expected and are damaged by strong pressure or rough handling. Pulling them out forcefully through a thick tube brings them out already broken. This is why gentle harvesting with a thin cannula is recommended.
The second is purification. Harvested fat contains blood and body fluid, anesthetic solution, and fragments of destroyed cells. If these impurities remain, they cause inflammation that interferes with retention and can lead to calcification. A filtering step such as centrifugation is needed.
The third is where the fat is placed. It has to go into a layer with good circulation so vessels grow in quickly. Areas where the tissue is firm or blood flow is poor are unfavorable.
The fourth is aftercare. Pressing or massaging the grafted area hard can scatter fat that is still settling, so patients are advised to avoid pressure in the early period. Smoking reduces blood flow and is cited as a factor working against retention.
| Condition | What to look at |
|---|---|
| Harvesting | Whether fat cells are handled so they sustain less damage |
| Purification | The process of filtering out blood, oil, and damaged cells |
| Placement | Whether it is placed thinly across multiple layers so vessels can reach it |
| Aftercare | Recovery conditions such as pressure, posture, and smoking |
Why TheLINE uses SVF alongside grafting
TheLINE Plastic Surgery Clinic applies SVF together with fat grafting. The key to retention lies in how quickly blood vessels connect.
SVF isolated from fat contains adipose-derived stem cells along with microvascular endothelial cells and growth factors. These are components involved in the process of forming new vessels. The approach is to add them to the fat being grafted.
Isolation is carried out in the dedicated laboratory on the fifth floor of the clinic. Fat harvested in the operating room goes straight into the laboratory for isolation and purification, so transport time is short.
Dr. Jaeho Cho, a board-certified general surgeon, has worked with fat and SVF since starting in molecular biology research in 1994, and Dr. Yoosuk Chung, a board-certified plastic surgeon, handles harvesting and surgery with him. Among TheLINE patients, some do not finish in a single session but observe the progress and then proceed with an additional round.
Conditions differ by area
Facial fat grafting involves smaller volumes but demands precision. A difference of a few millimeters changes the impression, and even a slight left-right discrepancy is noticeable. Areas that sit in different layers, such as the forehead, temples, cheeks, and nasolabial region, are each handled differently.
Breast fat grafting requires a large volume. That makes it hard to reach the desired size in a single session, so it is often divided into stages. Whether there is enough fat to harvest also has to be checked first.
Hip fat grafting is affected by sitting posture. Pressure in the early period works against the fat settling, so lifestyle guidance is given alongside.
In areas with thin skin such as the back of the hands or the top of the feet, even a slight excess makes the surface uneven. This is why the judgment required differs by area.
What does recovery look like?
The grafted area swells at first. During this period it looks larger than the amount placed, and this state is not taken as the final appearance.
The harvested area has to recover as well. Even in small volumes the harvest is a liposuction procedure, so that area goes through its own swelling and bruising. In effect, two sites are being managed at the same time.
For the first several weeks, patients are advised not to press or massage the grafted area, because the fat is still settling. Saunas and vigorous exercise are also resumed only after a set interval.
Volume decreases over time as fat that has not been retained is absorbed. Things settle over several months, and the appearance at that point is close to the volume that will be maintained. That is why judging the result and deciding on any additional procedure both wait until this period has passed.
Limits worth knowing
The retention rate cannot be predicted precisely in advance. Age and general health, the condition of the fat at the harvest site, and the blood flow at the placement site are all involved, and individual variation is large.
It often does not finish in one session. Fat may be placed with extra allowance to account for absorption, or an additional round may follow after observing the progress. Planning for several sessions from the outset is the realistic approach.
If there is not enough fat to harvest, the procedure is difficult to carry out. This applies when a large volume is needed in a lean body type.
Side effects are possible as well. Nodules and calcification at the grafted site, asymmetry, and infection can occur, and bruising and surface irregularity can remain at the harvest site. Unexpected inflammation or bleeding may occur, and the degree varies from person to person, so caution is required.
Frequently Asked Questions
What is the retention rate, generally?
The reported range is wide, so it is hard to state a single number. Variation by area, method, and individual condition is large, so explanations that guarantee a specific figure are worth viewing with caution.
Can't you just place as much as I want in one session?
If it is packed into one spot as a mass, vessels cannot reach the center, so it is absorbed or left behind as a nodule instead. That is why it is divided finely and scattered across multiple layers.
If I lose weight, does the grafted fat shrink too?
Retained fat consists of your own fat cells, so it responds along with changes in body weight. Significant weight loss can reduce the grafted area as well.
When is the result assessed?
It takes several months for fat that has not been retained to be absorbed. The appearance after that period is close to the volume that will be maintained, so any additional procedure is decided at that point as well.
How is fat grafting done at TheLINE?
TheLINE Plastic Surgery Clinic uses dedicated micro-grafting syringes to divide the fat finely and scatter it, and applies SVF isolated in the in-house laboratory to support the process of vessels growing in. Dr. Jaeho Cho and Dr. Yoosuk Chung handle everything from harvesting to grafting.
