In the first of a two-part article, Dr Lee Walker details the relevant anatomy to consider for lip augmentation and explains patient selection for treatment
Lip augmentation can be a clinical challenge. Clinical outcomes are defined by injection technique, the patient’s unique anatomy and the type and amount of filler used. The key to achieving and maintaining attractive and appealing lips is strongly related to understanding and respecting anatomy, aesthetics and associated challenges.1 Furthermore, a thorough knowledge of the ageing process is essential in appreciating what we need to focus on to achieve more ‘beautiful’ and youthful lips.2
In youthful Caucasian patients, the upper lip is usually narrower than the lower. The upper lip to lower lip ratio is approximately 40:60. In the Afro-Caribbean ethnic group this ratio is 50:50.3 A youthful lip will show the skin immediately above the vermillion border to have a smooth appearance without any visible rhytides. There are sharply defined philtral columns and a well-defined cupid’s bow centrally. The upper lip has a prominent medial tubercle with bilateral depressions. The lower lip has a corresponding small depression centrally and two lateral protrusions (Figure 1).2
On lateral profile, the upper cutaneous ‘white’ lip should be short with a concavity approaching the ‘red’ lip.4 The upper lip should project slightly further than the lower (around 2mm).4 According to a study, attractive female lips tend to have an increased vermillion height, increased nasolabial angle and an increased mentolabial angle (Figure 2).3
The ageing lip is characterised by:5-7
These features are further accentuated by a perioral ‘collapse’. This collapse is due to resorption of the craniofacial skeleton,5 hyperkinetic activity of the orbicularis oris6 coupled with fat atrophy.7
Lip deflation is not due to overall volume loss in the lip. The loss of ‘pouting’ is attributed to a redistribution of thickness of the lip towards length. This means that this ‘virtual’ volume loss is simply just a loss of elasticity with resulting ptosis.8 There is no volume loss in the lip.8
The lips are not only an important part of the central facial triangle, but they also play an essential role in facial expression, articulation of speech, masticatory competence, maintaining oral seal and defining soft tissue boundaries for the teeth. Shape and thickness differs between the upper and lower lip, and varies significantly between individuals and ethnic groups.
The orbicularis oris muscle consists of two parts; a lower and an upper part joined to the modiolus. These two parts are composed of two distinct portions, the pars marginalis and the pars peripheralis, which differ in location and function (Figure 5).9,10
The pars marginalis is located in the vermillion and acts as a sphincter. The pars peripheralis is located in the cutaneous lip and has a dilatory function. The fibres of the pars marginalis and the pars peripheralis come from the modiolus but are directed differently and are not within the same plane. The pars marginalis is located in front of the pars peripheralis, which gives the lips its curved shape.9,10
Figure 5: The anatomy of the lip21
There is huge variability in the number, course, diameter and location of the arterial supply to the lips.
The superior labial artery originates from the facial artery and is at most times superior or at the same level of the labial commissure, however it can occasionally be inferior to it. The diameter of the superior labial artery at its origin ranges from 1-1.8mm.11-18 The superior labial artery travels forward to the upper lip, passing deep to the zygomaticus major muscle. The superior labial artery is usually larger and more tortuous in its course than the inferior one. Into the upper lip, it enters the orbicularis oris muscle and travels between the muscle and the mucosa, along the edge of the upper lip.11-18
The inferior labial artery is also branched from the facial artery, generally below or at the level of the labial commissure and seldom above it. Its mean diameter in its origin ranges 1.2-1.4mm. As with the superior labial artery, the point at which the inferior labial artery branches from the facial artery and the distance between its origin and the labial commissure exhibit a high variability ranging 0.5-4cm with a mean distance of 2-2.5cm (Figure 6). After branching from the facial artery, it runs tortuously upward and forward deep to the depressor anguli oris muscle in its course to the lower lip. The artery penetrates the orbicularis oris muscle and runs tortuously along the edge of the lower lip lying between the muscle and the mucous membrane.11-18
Figure 6: Anatomy showing the arterial blood supply21
The patient should be medically fit and well. If the patient is susceptible to herpes simplex, pre-treatment antiviral medication may be prescribed, and treatment should not take place if herpes simplex is visible. Awareness of medications that predispose to bruising is essential (pain relief medication, non-steroidal anti-inflammatory drugs, anticoagulant medication, vitamin E). Informed written consent must also be signed, dated and initialled on every page.
Pre-operative and post-operative photographs in frontal and lateral views are critical. These photographs will highlight any asymmetry, which must be relayed to the patient prior to commencement of treatment. They will also serve as a ‘non-biased second opinion’ if the patient returns weeks later saying their lips look ‘no different’ or they are ‘uneven’. Identifying patient expectations and treatment goals at the consultation stage is one of the crucial stages in lip augmentation. Patients often ask for augmentation of the upper lip only, however this approach can lead to a ‘duck lip’ appearance, which is not usually considered aesthetically pleasing. I often use laminated photographs of lip dimensions related to facial beauty (Figures 7 & 8) to educate and counsel the patient.18
Figure 8: Most attractive lip ratios by rank. Facial attractiveness is highest with an average of +53% enhancement.19
A study published in The Laryngoscope suggests that a larger upper lip (duck lip) is the most unattractive ratio.19 It also suggests that facial attractiveness is highest when thin, non-treated lips are enhanced by 53%. This is useful when patients are requesting large volumes of filler. It therefore aids the practitioner in preventing overfill in the demanding patient.
When it comes to considerations, it is also vital to discuss post-operative outcomes, which can include swelling and bruising. The emphasis must be placed on social downtime ranging from two to 10 days. Patients should be made aware that this treatment may be difficult to hide from partners or colleagues. A patient alignment checklist is a useful tool to ensure the patient is a suitable candidate for lip augmentation.20
Achieving treatment goals with lip augmentation requires an in-depth knowledge of lip anatomy and clinical assessment of lip function. The best results are when the practitioner accentuates the patient’s existing lip architecture. The practitioner should understand the considerations and undergo appropriate measures for patient selection.
This article is the first of two on lip augmentation by Dr Lee Walker. His next article will detail the treatment side of lip augmentation including a discussion of technique and products.