Clinical Paper Review – Comparing Vertical and Horizontal Lip Filler Injections
Is there any evidence that vertical lip filler injection techniques are riskier than horizontal?
You may remember the blog we published recently where Dr Tim Pearce asked – Is a vertical lip filler injection technique more dangerous than injecting horizontally?
During the blog discussion, Dr Tim reviewed lip anatomy including rare anatomical anomalies, and explored the differences between vertical and horizontal lip filler injection techniques, alongside their potential risk factors for causing vascular compromise or vascular occlusion. He revealed his mental model and approach when treating lips, including considerations in relation to young versus mature lips.
Whilst debating the issues with his audience on social media, an esteemed colleague Dr Steven Harris referred him to an important clinical paper and cited it as evidence that vertical lip filler injection techniques, such as tenting, are riskier than horizontal approaches; something which Dr Tim disputes.
In this blog, he will review the clinical paper highlighted by Dr Harris to assess if it provides evidence that injectors should be avoiding vertical injection techniques when treating lips.
Dr Tim will be discussing more medical aesthetic training tips as part of his upcoming webinar series, so if you’re looking to increase your CPD-certified learning and want to learn more skills to make you a better practitioner, then step one is to register for the free webinars by Dr Tim.
Treating lips and their anatomical correlate in respect to vascular compromise
The published paper in question – treating the lips and its anatomical correlate in respect to vascular compromise – appeared in the Facial Plastic Surgery Journal in April 2019 and was authored by dermatologist, Dr Sahar Ghannam et al. (The full text of the paper is available as free-to-read).
This study has been regularly cited as evidence that vertical lip injections are riskier than a horizontal approach, but can we be certain of this fact and satisfactorily draw that conclusion when we dig deeper into the methodology of the study?
The authors tested their dermal filler injection techniques on three cadavers which had an average age of 85 years old (2 male, 1 female). The arteries were injected with red latex prior to the procedure which had a bi-fold effect of making the arteries stand out more clearly upon dissection and be resistant to penetration by a needle. A cross-sectional analysis of the lips was performed following each test procedure to find the relationship between the filler product delivered and the labial artery.
If you review the clinical paper yourself, you will note that the authors include detailed illustrative diagrams and treatment plans for each injection technique under investigation so you can compare them with your own practices.
Testing different lip filler injection techniques
The injection techniques tested ranged from superficial linear threading, referred to as a contouring technique, to deeper injections into the lip body, noted as volumising techniques. The authors reviewed techniques for treating both the upper and lower lips.
Linear threading along the vermillion border of the upper lip
This superficial technique showed no close relationship to the artery upon lip dissection. This is compatible with anatomical understanding, which notes that at this superficial level, the artery is, in most cases, protected by the orbicularis oris muscle and the product deposition will be a couple of millimetres above it.
Oblique angle of vertical entry into the upper lip
This is not quite a true vertical entry into the top lip, with an approach at an approximate 45° angle to the lip, pointing downwards towards the wet-dry border. This is a common technique and is often used and described as a vertical approach by many aesthetic practitioners.
Reviewing the illustrative diagrams from the clinical paper, we can note that the authors show injection points in the white part of the lip; upon written description, this is referenced as injecting into the vermillion border, but their diagram is contradictory. Dr Tim notes that this discrepancy is crucial as it would have a significant impact on the associated risk factors if injections were indeed placed 2-3mm above the pink part of the lips.
When assessing product deposition upon lip dissection, the authors concluded a close relationship with the artery, and noted the technique as high risk.
Superior angle of vertical entry into the upper lip
This has a much more superior entry point, with an approach at an approximate 90° angle to the lip, a true vertical injection technique. The needle enters the white part of the top lip and passes downwards into the body of the lip, where product is placed. Upon reviewing the dissection, the authors found a close relationship with the artery.
Cannula insertion into the upper lip
A horizontal-style injection technique using a cannula via an entry point at the corner of the lip to place product along the vermillion border of the upper lip. The results from this procedure produced varying and inconclusive data, with treatment on one side showing proximity with the artery, yet little relationship with it upon treating the other side of the top lip.
Vertical angle of entry into the lower lip
The results from this technique also showed some proximity to the artery. However, on reviewing the illustrative diagram and treatment plan, alongside the dissection result, Dr Tim was able to discern a potential flaw in the methodology. It is easily noted that there is a significant difference in lip size and natural volume between the youthful lips used in the illustration and the mature lips of the cadaveric sample. A consideration that Dr Tim highlighted in his previous blog with regards to treating young versus mature lips – older patients tend to have much smaller and thinner lips, due to atrophy and involution which has a direct impact on injection placement.
Inferior angle of vertical entry into the lower lip
This approach is very unusual and not one Dr Tim has seen in practice. The needle enters the white part of the lip, approximately 1cm below the lower lip, moving upwards into the pink part of the lip to deposit the filler. Dissection again showed proximity with the artery.
Cannula insertion into the lower lip
This followed the previously described horizontal-style injection using a cannula to place product along the vermillion border of the lower lip. The dissection results were consistent with proximity to the artery.
What conclusions can we draw from this clinical paper?
The authors concluded,
“Based on the cadaveric part of the present study, it should be noted that 58.3% of the volumising procedures were related to a potential intra-arterial injection because the product was injected deep inside the body of the lips. On the contrary, procedures aiming for contouring can be regarded as safer as in this case, the product was positioned in the subcutaneous plane which is separated from the arteries by the orbicularis oris muscle”.
This leads to the understanding that depth is the main risk factor and not the angle of entry. So, does this specific study have any bearing on the debate over horizontal versus vertical injection techniques and their riskiness?
Dr Tim believes that the answer is, “no, not really”, because this clinical paper is not a controlled test of vertical versus horizontal injection techniques but is a test of some subtly different injection techniques that the authors chose to explore. Similarly, many other variables have been changed during this study which makes it difficult to compare results in relation to our precise question. There also appears to be some contradictory evidence within the paper, as noted with the variable results from the cannula injections.
When approaching vertical injections, the authors appeared to use techniques which are not commonplace. They describe injecting into the white area of both the upper and lower lips, and are injecting significantly superior to the top lip, whereas most clinicians will inject into the vermillion border in practice. By approaching from much higher up, the needle would pass through the orbicularis oris when going deeper, which is a different trajectory and risk profile to injecting from the vermillion border in a downwards direction.
The rationale for injecting into the white part of the lip for this study is unknown, but Dr Tim suggests the use of cadavers may have a bearing on this choice. Comparing a very small selection of cadaveric samples, all over 80 years old, alongside injection techniques rarely used in practice is unlikely to produce real-life results which can be used for adequate risk assessment when we are treating a much younger patient cohort with different needle entry points.
Take home message
Dr Tim Pearce’s conclusion is that the real risk when injecting the lip lies in the proximity to the retro orbicularis oris space and that varies according to your injection technique, but it is also more likely that you will be in that space when the lip is aged, small, thin, or atrophied. A fuller, more youthful lip will likely mean that your needle is in an anterior pocket that is further away from this space.
As aesthetic clinicians, we must therefore look to adjust our injection techniques to suit the patient in front of us, taking into consideration their age and their natural lip shape and volume – there is no one-size-fits-all lip filler injection technique. He also believes that it is the angle of approach rather a simple horizontal versus vertical approach that changes the risk to the labial artery.
Dr Tim is keen to know your thoughts on the topic and which lip filling injection techniques you prefer and why. You can follow Dr Tim to discuss on Instagram.
Aesthetics Mastery Show
Vertical Lip Technique
This blog follows our recent Aesthetics Mastery Show, in which Dr Tim Pearce discusses whether vertical lip injection techniques like tenting are more or less likely to cause a vascular occlusion than horizonal lip techniques, looking at the evidence for both perspectives. He also discusses lip anatomy and shares his mental model of how the two lip injection techniques are more or less likely to occlude the artery.
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