Hip Dip Fat Grafting: A Contour Made of Bone, a Graft That Half Survives, and a Filler No Regulator Approved for the Hip

Hip dip fat grafting is the newest small procedure to be built around a phrase that did not exist in the clinic ten years ago. The phrase is "hip dips," sometimes "violin hips," and it describes the inward curve on the side of the body between the crest of the pelvis and the bony prominence at the top of the thigh. Every human skeleton has the curve to some degree. On some bodies it reads as a smooth line, on others as a visible notch, and since roughly 2019 the notch has been a topic of short-form video, a target for workout programs, and, increasingly, a line item on a body-contouring quote.

The surgical answer is autologous fat transfer: liposuction from the abdomen, flanks, or thighs, processing of the harvested fat, and injection of a few hundred milliliters into the soft tissue over each hip to round out the curve. It is usually offered as part of a Brazilian butt lift and sometimes on its own. The pitch is that it uses the patient's own tissue, that the volumes are modest, and that the recovery is mostly the recovery from the liposuction rather than from the grafting.

The pitch is not wrong. It is incomplete in three ways that matter. The dip is a feature of bone and fascia, not of fat, so the graft is being asked to disguise a structure rather than replace a deficit. The tissue over the lateral hip is one of the tightest and least vascular envelopes on the body, which is a poor place to ask transplanted fat to survive. And the non-surgical alternatives that clinics offer for patients who lack donor fat are, without exception, used outside any regulator's approval for that site. Those three facts are the article.

What a hip dip is, and why it is mostly skeleton

The short answer: a hip dip is the concavity between the iliac crest and the greater trochanter of the femur, and its depth is set by bone geometry, the thickness of the muscle that fans across it, and the way the skin is tethered to the deep tissue in that exact region, none of which the patient chose or can train away.

The anatomy takes a paragraph. The iliac crest is the rim of the pelvis a person can feel at the waist. A hand's width below and slightly forward is the greater trochanter, the knob at the top of the thigh bone where the hip muscles attach. Between the two lies the gluteus medius, a flat fan of muscle running from the outer pelvis down to the trochanter, and in front of it the tensor fasciae latae, a small muscle that feeds into the iliotibial band, the long tendon down the outside of the thigh. Over all of that, the subcutaneous fat is thin and the skin is anchored down. Where the fat is thin and the bone is far from the surface, the body curves inward. That inward curve is the dip.

Plastic surgeons have a name for the anchoring. In 2001, Rohrich, Smith, Marcantonio, and Kenkel published a paper in Plastic and Reconstructive Surgery describing the zones of adherence, five regions of the lower body where the superficial fascia is densely bound to the deep fascia beneath it, so that the fat cannot glide and the skin cannot be easily lifted. The lateral gluteal depression, which is the anatomic term for the hip dip, is one of the five. The paper's purpose was to warn liposuction surgeons that suctioning these zones produces contour deformities, and the same adherence explains why grafting into them is harder than grafting into the buttock: there is less room, the septa resist the cannula, and the tissue does not expand to accept volume the way a loose envelope does.

The other determinant is the skeleton itself. A pelvis that is wide at the crest and narrow at the trochanters produces a deep dip. A long vertical distance between the crest and the trochanter, the "high hip" pattern, produces a long dip. Constantino Mendieta's classification of the gluteal frame, published in Clinics in Plastic Surgery in 2006, sorted the lateral outline from waist to thigh into four frames, the A, V, square, and round, and its value for a hip dip patient is its honesty: the frame is skeletal, and the lateral depression is a component of the frame rather than a flaw laid on top of it. The rounded outline that patients bring in as a reference photograph belongs to a round frame with a gynoid fat distribution. It is not a version of the square frame that has been fixed.

Fat distribution finishes the picture, and it works in a direction that surprises people. Gynoid fat settles on the outer thigh below the dip and on the flank above it, so a fuller lateral thigh, the saddlebag, deepens the appearance of the notch between them. Some of the most visible hip dips belong to people who carry more fat, not less, and for them the honest first conversation is about the thigh below the dip rather than about adding anything to the dip itself. No medical body classifies hip dips as a condition. There is no diagnostic code, no prevalence study, and no threshold at which a dip becomes abnormal, because the dip is the shape of a joint that has been there since the species stood up.

Why squats do not fill it

The short answer: the gluteus medius and tensor fasciae latae can be strengthened, but they are thin muscles anchored to a bony floor and a tendon, and no amount of hypertrophy turns a skeletal concavity into a convex hip, so training changes tone and posture more than it changes the outline.

The workout programs are built on a plausible idea, which is that the dip sits over muscle and muscle can grow. The problem is which muscle. The gluteus maximus, the one that responds to squats and hip thrusts, sits behind the hip and shapes the buttock; it does not occupy the lateral depression. The muscles that do, the gluteus medius and the tensor fasciae latae, are flat and modest in cross-section, and the lowest point of the dip lies over the iliotibial band and the trochanter, which are tendon and bone. Tendon does not hypertrophy. A person can spend a year on side-lying abductions and clamshells and gain measurable hip stability, a slightly lifted upper buttock, and a marginally softer transition, and the notch will still be there, because the notch is the space between two bony landmarks and the muscles between them were never going to fill it.

What does change the dip is body weight, in both directions. Weight gain in a gynoid pattern pads the flank and the outer thigh and, to a lesser extent, the dip itself, so the outline smooths. Weight loss does the opposite, and the patients who arrive most distressed about their hip dips are often those who have recently lost weight, sometimes on a GLP-1 drug, and have watched a curve they did not notice become a notch they cannot stop noticing. That history matters for the surgery, because the graft will be harvested from fat that is now scarce and placed in a body that may keep changing.

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A hip dip is the space between two bones. Fat grafting does not close the space. It hangs a curtain in front of it, and the curtain is made of tissue that the lateral hip is unusually bad at keeping alive.

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How hip dip fat grafting is done

The short answer: it is a small-volume autologous fat transfer, typically 100 to 300 milliliters per side, harvested by liposuction from the abdomen, flanks, or thighs, processed to remove fluid and oil, and placed in the subcutaneous plane over the lateral hip through small cannulas in many thin passes, sometimes after releasing the fibrous attachments that hold the dip down.

Harvest first. The candidate for hip dip grafting is often slim, and slim patients have the least fat to donate, which is the first constraint on the operation and one the consultation should raise early. A surgeon needs to harvest more than will be injected, because processing discards a share and because the graft will shrink; a patient near the lower end of the range discussed in the piece on BMI limits for cosmetic surgery may simply not have enough. The harvest itself is standard tumescent liposuction, usually under general anesthesia or deep sedation when the volumes are meaningful, occasionally under local for a small isolated case. The lipoaspirate is then decanted, filtered, or centrifuged, and the biology of what survives that handling is laid out in the piece on fat graft survival.

Placement is where the lateral hip differs from the buttock. Because the tissue is adherent and thin, the surgeon cannot deposit a bolus and expect it to spread. The graft goes in through one or two small incisions in fanning tunnels, a fraction of a milliliter per pass, layered from deep subcutaneous to superficial, so that each thread of fat sits against living tissue that can feed it. Some surgeons first pass a blunt cannula or a subcision needle through the septa to release the tethering and create space; without that release, the tight envelope back-pressures the injection and fat placed under pressure dies. The recipient site sets the volume ceiling. A hip that accepts 250 milliliters comfortably will not accept 400 by force, and surgeons who overfill on the first pass are trading a fuller two-week photograph for lumps and oil cysts at six months.

Safety is where the buttock and the hip converge. Fat grafting to the gluteal region became the deadliest cosmetic procedure per case in the 2010s because fat injected into or beneath the gluteal muscles can enter the large gluteal veins and travel to the lungs. A 2017 survey-based report by Mofid and colleagues in Aesthetic Surgery Journal estimated the mortality of gluteal fat grafting at about one in three thousand cases; the multi-society task force that followed, joined by ASPS, ASAPS, ISAPS, IFATS, and ISPRES, issued the rules that now govern the procedure: subcutaneous placement only, never into or under muscle, cannulas of four millimeters or larger, and no downward angulation. Florida wrote the subcutaneous-only rule into regulation in 2019, added a requirement for ultrasound guidance during injection in 2022, and capped the number of such cases a surgeon may perform in a day by statute in 2023. A follow-up estimate by Rios and Gupta in 2020 put the mortality after those protocols closer to one in fifteen thousand. The lateral hip is, anatomically, a safer target than the buttock: the trochanter and the iliotibial band sit beneath the graft and there are no large veins in the plane. But hip dip grafting is most often performed as a component of a Brazilian butt lift, under the same anesthetic, with the same cannulas, on the same day, so the risk profile a patient should read is the one in the piece on BBL safety protocols, not the one for the hip in isolation.

What survives, and what goes wrong

The short answer: expect roughly half to two thirds of the injected volume to persist at six months, with the lateral hip toward the low end of that range because the tissue is tight and poorly expandable; the common problems are under-correction, asymmetry, palpable lumps and oil cysts from fat that died, donor-site irregularity, and a result that rises and falls with body weight.

Retention first, because it is the number that determines whether the patient is buying one operation or two. Across body sites, the published range for fat graft survival is wide, and most surgeons quote a working figure of fifty to seventy percent of what was placed. The lateral hip tends to underperform that figure for the reasons above: adherent tissue, a thin layer, a recipient bed with limited blood supply, and a site that is in motion with every step. The practical consequence is that a meaningful share of patients, plausibly a quarter or more in practices that graft the site routinely, are offered a second session at six to twelve months, and a second session requires a second harvest from a donor supply that was already limited. A quote that does not mention the possibility of a second round is a quote for half a procedure.

Then the fat that does not survive. Dead adipocytes do not vanish; they become the oil cysts, firm nodules, and calcifications described in the piece on fat necrosis after fat transfer, and over the hip they are easy to feel through thin skin and occasionally visible as a ridge. Overfilling and bolus placement raise the rate. The contour problems are the mirror image of the goal: a graft that fills the dip but also pads the flank above it produces a square, shelf-like hip rather than a curve; a graft that takes on one side and not the other produces an asymmetry that was not there before; and a donor site suctioned aggressively to feed the graft can end up with its own dents, which is the trade described in the review of high-definition liposuction under a different name.

The result is also not fixed. Grafted fat is living tissue that behaves like the tissue it came from, so it grows with weight gain and shrinks with weight loss, a dynamic covered in the piece on whether fat comes back after liposuction. A patient who grafts at a stable weight and holds it can expect a durable result. A patient mid-diet, or one who grafts and then begins a GLP-1 drug, may watch the graft deflate along with everything else, and the dip that returns will be the original dip with a layer of scar over it.

Recovery is mostly the donor site, but the graft has its own rules. Pressure kills fresh fat, so garments are worn with cut-outs or foam relief over the hips, and patients are told not to lie on their sides for two to three weeks, which is a harder instruction than it sounds for a body that has just had its abdomen suctioned and cannot lie on its front either. Unlike the buttock graft, the hip graft does not forbid sitting. Swelling over-reads the result for the first month, so a hip that looks fuller than planned at two weeks is not the result; the graft is judged at three months and settled at six. Infection is uncommon. The signature complication is disappointment: a dip that was skeletal to begin with, softened rather than erased, at a cost the patient thought was buying the reference photograph.

The non-surgical menu, and what the FDA says about it

The short answer: nothing injectable is approved in the United States for the hip. Poly-L-lactic acid is used off-label there in many vials over several sessions, the large-volume hyaluronic acid body fillers sold abroad are not approved here, silicone and other biopolymers are illegal to inject for contouring, and solid hip implants are rare and complication-prone.

The FDA's consumer page on dermal fillers is unusually plain on this point: the agency states that it has not approved any dermal filler to increase the size of the buttocks or for large-scale body contouring, and it warns against the practice. That leaves every filler option for the hip dips in the off-label category at minimum. The most common is poly-L-lactic acid, marketed as Sculptra, which the FDA approved in 2009 for facial folds and which works by provoking collagen rather than by adding volume directly; the mechanism and timeline are laid out in the piece on how long Sculptra takes to work. Used on the hips, it requires on the order of five to ten vials per side per session, two or three sessions spaced weeks apart, and months to show; at several hundred dollars a vial the total often approaches the cost of the fat graft, and the result fades over roughly two years. The nodule risk described in the piece on biostimulatory fillers applies, and over the thin skin of the lateral hip a nodule is easy to find.

The hyaluronic acid products designed for body contouring, sold in Europe and elsewhere under a CE mark in bottles of tens of milliliters, are not FDA-approved, and the cases of migration, delayed inflammatory nodules, and prolonged swelling in the body-filler literature belong to those products. A clinic in the United States offering "body filler" for the hips is using a facial product off-label in volumes it was never studied at, or an imported product it should not have. Below that on the ladder is liquid silicone and the biopolymers, injected in unlicensed settings and responsible for the granulomas, migration, and deaths covered in the piece on illegal silicone injections; the hip dips are one of the sites those injectors advertise.

Solid implants exist. Hip implants are carved or molded silicone elastomer placed beneath the fascia over the lateral hip, mostly performed outside the United States, and their track record, where it has been published, features seroma, migration, visible edges, and removal rates that make them a last resort rather than an alternative. There is no device approved specifically for that site in this country. And there is the option that the consult rarely names: reducing the fullness of the outer thigh below the dip, when a saddlebag is what makes the notch read as deep, which changes the outline by subtraction rather than addition and is a liposuction question rather than a grafting one. For a great many patients, the honest outcome of a well-run consultation is the recognition that the dip is the shape of their pelvis, that the reference photograph belongs to a different skeleton, and that the surgeon can soften but not rewrite the frame.

The honest summary

A hip dip is the lateral gluteal depression, the space between the crest of the pelvis and the top of the thigh bone, and it is one of the five zones of adherence where skin and deep fascia are bound tightly together over a bony floor. Its depth is set by the skeleton, by the thickness of two flat muscles that do not hypertrophy into a mound, and by a fat distribution that often deepens the dip by padding the thigh below it. It is not a condition, and no exercise program changes the frame it belongs to. Fat grafting can soften it: a few hundred milliliters per side, harvested from a donor supply the typical candidate has little of, placed in thin threads into an envelope that resists volume, with roughly half to two thirds surviving and a real chance of a second session. The lateral hip is a safer injection site than the buttock, but the procedure is usually bundled with a Brazilian butt lift and inherits its risk, its anesthetic, and its protocol requirements. The failures are lumps and oil cysts from fat that died, a shelf where a curve was intended, asymmetry, donor-site dents, and a result that tracks body weight. Every non-surgical alternative is off-label, unapproved, or illegal for the site, and the solid implants are rare for good reason. The decision points are whether the dip is bone or fat, whether the patient has fat to give twice, and whether the surgeon will say plainly that the goal is a softer notch rather than the outline in the reference photograph. A clinic that quotes the graft without answering those three questions has sold a procedure for a shape it cannot deliver.