Retaining ligament filler — how far does the evidence actually go

The retaining ligaments are the fibrous structures said to tether facial skin and soft tissue to bone or to deep fascia. The ligaments named most often sit at the zygoma, in front of the masseter, at the mandible, and around the orbicularis muscle. The starting point of this technique is that as these structures loosen with age, tissue folds downward along a particular line rather than deflating evenly.

So treatments sold as “retaining ligament filler”, “ligament filler” or “lifting filler” are described as aiming not to fill a hollow but to create a direction. Note, though, that these are marketing names, not the name of a standardised technique. As far as we could establish, there is no standard protocol defined under the name “retaining ligament filler” — which points, how many mL, at what depth.

That last row is why this column exists. The two views are not separated by which logic sounds better but by the thickness of the data behind them. How fillers differ from boosters is set out separately in what separates a filler from a booster.

Of the papers describing ligament-directed injection, the one cited most widely is the report Cohen and colleagues published in the Journal of Cosmetic Dermatology in 2020. It describes calculating a vector and injecting beneath the fascia, on the premise that laxity of the orbital, zygomatic and masseteric ligaments contributes respectively to brow descent, deepening nasolabial folds and jawline descent.

We also record what we did not find. We could not find a trial randomising ligament-directed injection against conventional injection. We could not find a trial testing this technique with sagging as the primary endpoint. Nor could we find a study that followed the durability of this technique separately.

We cite the same paper with the same qualifiers in our columns on cheek descent, nasolabial folds and facial sagging. Not writing it differently from page to page is our standard.

“We target the ligament” rests on the premise that it is settled where the ligament is and what shape it takes. That premise has been shaken.

Take the tear trough ligament. Since Wong and colleagues described it in 48 cadaveric hemifaces in 2012, it has been the standard diagram for the region. Then a 2018 micro-CT study of 11 cadavers and 22 specimens reported that it may not be a separate ligament at all but one continuous complex with the orbicularis retaining ligament. Beyond that, histological work disputing that a true ligament exists is also being cited — work we have verified only at second hand.

More on the lower eyelid is in our column on tear trough hollows.

One reason retaining ligament filler is described as low-commitment is the premise that it will be absorbed within months anyway. Data from the lower eyelid have undermined that premise.

• In a systematic review of 23 studies and 2,048 patients, 85% of the volume of lower-eyelid hyaluronic acid remained at 15 months. In the same review there were no randomised controlled trials at all, adverse events ran at 30.2% (466/1,545), contour irregularity at 7.57%, and hyaluronidase was needed in 5.18%
• In a study following 155 patients for a mean of 785 ± 536 days, the improvement at 18 months was not statistically different from that at 6 months (p = 0.57). That means it lasted — and equally that it was still there

In practice this means one thing. Booking a top-up every six months by the calendar can accumulate. The timing of a repeat is better decided by the state of the tissue than by a date. How we set intervals is in our column on how many sessions are needed.

Ligament-directed injection is a depth-sensitive technique. Describing it as sub-fascial assumes the fascia sits at a broadly consistent level. Measured data say otherwise.

• In a retrospective review of ultrasound data from 200 patients who had lower-face rejuvenation (mean 41.1 ± 13.7 years), the superficial and deep fascial boundaries lay more superficially in older, male and leaner patients. In the same study, superficial fat became thinner with age
• In a study measuring 30 embalmed cadavers with a three-dimensional scanner, facial skin was 2.1 ± 0.4 mm and superficial fat 5.2 ± 1.9 mm. The standard deviation of the superficial fat is more than a third of its mean — that is, it varies widely between people. Embalmed-cadaver data carry their own limitations

So “a few mm beneath the fascia” is not a number that can be used without regard to who is in front of you. In a lean or older patient the same depth means a deeper plane. That is where the reputation of this technique as unusually operator-dependent comes from.

The points where retaining ligaments are named overlap with places that are deep, and crossed by named arteries. The most important risk in this technique is therefore not an underwhelming result but a vascular event.

• In a review collecting blindness cases, the distribution of 48 new cases between January 2015 and September 2018 was nose 27 (56.3%), glabella 13, forehead 9, nasolabial fold 7, cheek 2, upper eyelid 1, with complete blindness in 25 (52%). The midface is not the most common site, but cases are on record
• The same authors wrote that “vascular injury has occurred with cannulas of various gauges”, recommended 25G or larger and considered 27G or smaller more likely to pierce a vessel wall
• The occlusion figures quoted most often (needle 1 in 6,410, cannula 1 in 40,882) come from a survey of 370 dermatologists recalling the previous ten years, not a comparative trial. The possibility that cannulas were chosen for the riskier areas in the first place is baked into them

Hyaluronic acid filler is reversible in the sense that it can be dissolved with hyaluronidase. This is the reassurance offered most often when the technique is recommended. The limits are worth knowing precisely.

• Even among reversible materials, how readily they dissolve differs a great deal. Within the range we reviewed, the gap between products reached 12.5-fold — the firmer and more cross-linked the gel, the less it dissolves
• Materials that are not hyaluronic acid do not dissolve this way. Some products offered for ligament points are not hyaluronic acid, so what is being injected has to be established first
• Dissolving is not itself a harmless procedure. It acts on the hyaluronic acid native to the tissue as well, and allergic reactions are reported rarely

The detail is in our column on hyaluronidase. Writing down the product name and its composition before anything is injected is what helps most later.

In South Korea, hyaluronic acid filler is licensed as a medical device, not a drug. Within the range we checked, the approved intended use is worded around wrinkle correction and volume replacement.

A device licence number and a medical-advertising review number are different numbers; the distinction is set out in our column on approval numbers. Approved indications abroad may differ from the Korean licence, so it is better not to infer Korean approval from overseas material alone.

• We first separate descent from deflation. If the shape changes markedly when you lie down, that points to displacement; if it still looks hollow lying down, that points to volume. Most people have both, and this examination is not itself a validated tool
• We look for a border line. If the tissue folds along a particular line, the ligaments are part of the picture — and then we say first where the limits of any treatment lie
• We do not hide the level of evidence. When we describe the ligament view, we say in the same breath that the data behind it are a 45-patient case series
• We put reversible materials on the table first and record the product name and composition
• We do not set repeat treatment by the calendar, because there are data showing filler in this region persists longer than assumed
• We fix how we will judge the result before treating. Photographs under the same light, the same angle and the same expression are the reference. Since validated scales for sagging itself are scarce, we also record validated neighbouring measures such as a nasolabial fold grade

How we break sagging down is in our column on loss of firmness, and the layer-by-layer approach to the whole face is in facial sagging.

Written and reviewed by Lee Chi-Hak, MD, medical director of Miso Clinic in Daegu, South Korea. Every study cited above is given together with the conclusion of the original and its limitations, and where we could not verify something, we have said that we could not verify it.