Lip Implants

Anatomy and Physiology

The lips divide into “red” and “white” components, largely as a historical artifact of Euro-centric publications in the aesthetic surgery literature. As these terms are well-entrenched in the medical literature we will use them here for the sake of brevity and comparability to existing publications, to facilitate education and understanding. The red lip is a mucous membrane (representing the wet and dry vermilion; the actual coloration varies according to the genetic background of each patient), while the white lip (cutaneous lip, also variable in accordance with the background of each patient) is a cutaneous structure. The vermilion border represents the mucocutaneous junction (i.e., the demarcation between the red and white lip). The red lip further subdivides into a dry and wet portion, with the former located along the anterosuperior portion of the red lip. This line of demarcation represents the plane of apposition of the lips: the dry portion is external and visible when the mouth is closed and at rest, while the wet is internalized. The upper lip is composed of the philtrum and tubercle centrally, the paired philtral columns laterally, and the white roll of the vermilion border. The orbicularis oris muscle, which is innervated by the motor branches of the facial nerve, maintains oral competence by acting as a circumoral sphincter. The horizontal fibers of this muscle attach to the modiolus and philtral columns, with contraction producing a tightening of the upper lip.[1][3][4]

Skin laxity associated with aging causes lengthening of the cutaneous portion of the lip, occurring in concert with shortening of the visible mucosal surface and flattening of the lip overall. The vermillion inverts, resulting in decreased lip pouting. Lips of advanced age take on a two-dimensional, flattened appearance compared to the fuller, pouty, youthful lip. Volume restoration reestablishes the three-dimensional structure of youth. The lower lip is less commonly thin in isolation, largely because it is less prone to shrinkage over time.[1][5]

Indications

Hypoplastic lips are the primary indication for lip augmentation, which may be age-related or not. While a variety of injectable fillers are available (e.g., hyaluronic acid), they are temporary, requiring repeated injections at several month intervals to sustain lasting results. For patients who have needle-phobia or who are looking for a more permanent and more cost-effective solution to lip augmentation (relative to undergoing repeated injections with fillers), lip implantation with an alloplastic implant is the option of choice.[1][6] 

Areas of the lip/peri-oral region addressed with lip implantation[2]:

• Decreased vermilion height
• Decreased pout (lack of effacement)
• Perioral lines and wrinkles
• Decreased volume (fat and muscle atrophy)
• Excess visible dentition

Guidelines to improve aesthetic outcomes with lip augmentation (to avoid "duck" or "sausage" lips[7][8]):

• Lip surface area: the most attractive lip augmentation should create roughly a 50% increase in surface area from baseline. Note: The lip surface area should equal approximately 10% of the height of the lower third of the face. 
• Lip vertical height (assessed on frontal view): the upper to lower lip height ratio should be between 1.6:1 and 2:1 (i.e., the lower lip should be taller than the upper lip).
• Lip projection (assessed on lateral view): referencing a straight line from the subnasale to the pogonion, the upper lip projection should be 3.5 mm anterior to the line and the lower lip 2.2 mm, roughly equal to a 1.6:1 ratio (i.e., the upper lip projections should be slightly more than the lower lip) 
• Lip width: should be approximately 40% of the width of the lower face

Contraindications

First and foremost, lip implants will not correct pre-existing lip asymmetry, for which fillers such as hyaluronic acid are preferred. Second, a relative contraindication to lip implants is “razor-thin” lips, where insufficient tissue or vermilion show may preclude fitting even the smallest (3 mm) alloplastic implant.[6] In patients with thin lips, the implant may become visible due to aggressive distension of the mucosa, or be at increased risk of extrusion or infection with normal lip movements postoperatively. If a patient with excessively long white lip and thin red lips desires lip augmentation with alloplastic implants, the surgeon should first perform a lip lift and/or mucosal advancement procedure 3 to 6 months prior to lip implantation.[2][9]

Equipment

A typical soft tissue or plastic surgery pan, and additional materials should include:

• Marking pen
• paper ruler
• No. 15 blade
• Small straight sharp scissors (e.g., Iris)
• Tendon passer
• Forceps
• Suture materials (4-0 Chromic or Vicryl) 

Though there have been many implant materials used, currently there exist several types of implants that may be safely used, depending on the preference of the surgeon and/or the patient.[1][6][9][10][11][12]

Autogenous Implants

1. Fat - usually harvested via concomitant face, neck, or body liposuction, the surgeon typically places the fat via injection or cannula technique, similar to augmentation with fillers. NOTE: fat augmentation may result in prolonged swelling, asymmetry, or a nodular appearance given due to its unpredictable absorption/survival rate (especially in mobile areas such as the lips).[13]
2. Superficial musculoaponeurotic system (SMAS) – harvested during a concomitant facelift
3. Postauricular fascia – temporalis muscle fascia
4. Scar tissue (if available, usually from previous facelift/neck lift scars)

Alloplastic Implants

1. Extended polytetrafluoroethylene
2. Silicone – commercially marketed and available in 3 diameters (3, 4, and 5 mm) and three lengths (55, 60, and 65 mm). The standard size most routinely used in practice is the 4-mm-wide prosthesis.

To improve aesthetic outcomes and lessen complications, the surgeon must be prudent in choosing the correct implant size. First, use a conformable ruler (e.g., paper ruler) to measure the distance of the wet-dry lip from commissure to commissure, with the lips slightly parted. NOTE: do not measure the patient's lips with the mouth open. The optimal prosthesis length should be several millimeters less than the commissure-commissure distance. Because of the curved shape of the upper lip compared to the lower lip, it is not uncommon for implant sizes of the upper and lower lip to differ.[2]

Personnel

Though not necessary, an assistant (often a surgical scrub technician) is useful to help with instrument delivery and/or retraction if needed.

Preparation

Medications

• As for most cosmetic procedures, patients are asked to abstain from smoking and use of any blood-thinning agents within 1 to 2 weeks of the procedure. Some surgeons will require antiviral medication starting one day prior to surgery and continuing for ten days postoperatively to prevent posttraumatic herpetic lesions, particularly in patients with a history of zoster/shingles.[6]

Marking

• First, the surgeon must measure the lip to ensure appropriate implant sizing; the measurement is from oral commissure to oral commissure along the wet-dry junction of the red lip. Implants that are too short will have visible tapered ends shy of the commissure.[9] The wet-dry junction of the red lip should be marked, as this helps ensure a uniform dissection pocket.

While lip implantation is possible under general anesthetic, most surgeons elect to perform lip implants under local anesthesia. A regional block is performed using an injection of a buffered solution of 1% lidocaine with epinephrine (1:100,000) targeting the infraorbital and mental nerves bilaterally. Then, each commissure is infiltrated with this solution. Finally, the local anesthetic is injected into the deep submucosa of the lip along the previously marked wet-dry border, with care to remain superficial to the orbicularis oris muscle.[6]

Technique or Treatment

Herein we describe lip implantation using an alloplastic implant, a quick and straightforward technique with little downtime that is well-tolerated, safe, and provides a natural look and feel to the lips.

After the patient is prepped and draped in a sterile fashion, 4 to 5 mm transverse commissural incisions are made bilaterally with a sharp scalpel (the commissural incision prevents medial displacement). Using small, straight operating scissors (e.g., Iris), a uniform submucosal pocket is developed in the lip along the wet-dry border to the midline. Dissection should be in a deep submucosal plane and limited to 2 mm from the marked wet-dry line to reduce the chance of depth malposition and implant migration, respectively. It is essential to maintain a consistent depth along the length of the lip to ensure an even appearance. Avoiding making the pocket too superficial will prevent the tapered ends of the implant from becoming visible. This same maneuver is performed from the commissural incision on the contralateral side, resulting in the convergence of the two pockets into a single tunnel along the entire length of the wet-dry lip.

Next, a curved tendon passer is advanced from one end of the submucosal tunnel to the other until it emerges from the contralateral incision. The implant is grasped with the passer and brought through the tunnel until both ends of the implant are exposed. The implant is then “flossed” from side to side until equal lengths extend beyond the commissural incisions. (Note: some authors recommend using smaller implants that do not span the entire width of the commissure to mitigate migration). Finally, the ends of the implant get embedded underneath the commissural incisions. If the surgeon is placing lower lip implants, they are done in the same fashion, through the same incisions, also using a submucosal dissection plane. A 4-0 absorbable suture (chromic gut or Vicryl) is used to close the incisions in either simple interrupted, figure-of-eight, or mattress fashion. Regardless of the suture or technique used, incorporating deep submucosa and muscle within each stitch will help mitigate migration.

NOTE: The technique described above is appropriate for both alloplastic and autogenous implants.[6][9]

Complications

Lip implants represent a lasting, low-risk option for augmenting the lips with high satisfaction rates; however, the patient undergoing lip implantation should be aware of the potential associated risks, which include[3][6][14]:

• Malposition (7 to 10%): The most common complication of lip implantation is malposition, which is likely due to uneven tunneling in the submucosal plane or asymmetry in placement. 
• Extrusion (less than 1%): extrusion of an implant may occur if severe asymmetry and wound breakdown occur. This extrusion is avoidable by using the correct size implant, maintaining proper dissection planes, maintaining a small/narrow submucosal pocket, and using sound suture technique to close the commissure incisions. Instructing the patient to avoid heavy manipulation of the implanted area (e.g., talking, chewing, massaging) for the first several days after implantation may also help prevent malposition/extrusion.
• Need for revision/size adjustment (1 to 10%)
• Capsular Contracture (1%): expanded polytetrafluoroethylene implants, in particular, have been shown to shrink and contract with time, leading to an irregular and often asymmetric contour. As a result, their use has gone mostly out of favor.
• Infection (less than 1%): Infection is rare, but it may result from any type of implant.; this can typically be treated with systemic antibiotics, though it may require implant removal if the infection is severe.
• Dissatisfaction (1%)
• Dissatisfaction requiring removal (4%)
• Prolonged edema and ecchymosis (majority resolves between 1 to 2 weeks)

Clinical Significance

Lip augmentation with an alloplastic lip implant represents a quick, safe, cost-effective, and low-risk option for patients looking to augment and/or rejuvenate hypoplastic lips. Aesthetic outcomes are excellent in the hands of a knowledgeable and experienced surgeon, results are long-lasting, and patient satisfaction is high.

Enhancing Healthcare Team Outcomes

It is imperative to identify risk factors and perform a thorough assessment of the patient before performing a limp implant. A team approach is an ideal way to limit the complications of this procedure. Before surgery, the patient should have the following done:

• Evaluation by a surgeon experienced in selecting the appropriate patient for the surgery
• Evaluation by the primary care physician and anesthesiologist to ensure that the patient is fit for anesthesia

Following surgery, the patient should be evaluated and monitored by a perioperative nursing specialist providing support and patient education as well as coordination of follow-up care.

An interdisciplinary team comprised of an experienced surgeon, anesthesiologist, and surgical assistants, and operative nurses should perform the lip implant for the best outcomes. Close follow-up during the initial post-operative period, either by a wound care nurse and/or clinician experienced in the post-operative care of lip implants should monitor the patient for possible complications, including bleeding or infection. It is also crucial the team works together to counsel the patient on avoiding strenuous activity, heavy lifting, or bending over during the first several days post-operatively to prevent such complications. Patients should also avoid aggressive manipulation of the perioral region until 7 to 14 days postoperatively. [Level V]

Coordinated interprofessional team care involving physicians, specialists, and specialty-trained nurses is essential to achieving positive results in lip implant procedures. [Level V]

Nursing, Allied Health, and Interprofessional Team Interventions

Recovery after lip implantation is relatively quick and easy. Adequate pain medication is appropriate, as patients often report mild peri-oral pain for 1 to 2 days postoperatively. To minimize edema and ecchymosis, the patient should place ice packs around the mouth/lips intermittently for the first 24 to 72 hours, sleep with the head elevated for one week,  and avoid vigorous activity for two weeks. A low dose of corticosteroid taper may help lessen bruising and swelling as well. Patients should be instructed to avoid aggressive manipulation of the perioral region for 7 to 14 days to mitigate migration/extrusion of the implant and to decrease inflammation. Patients are asked to return at 1 and 2 weeks for wound assessment and residual suture removal, respectively.  Some authors advocate that "oral exercises" (e.g., wide mouth opening, smiling, puckering lips) be performed daily from 3 weeks to 3 months post-operatively, helping with overall healing and to create a more natural look and feel to the implant. The majority of bruising and swelling should resolve by two weeks, though photographic documentation should potentially wait until around three months postoperatively for cases of residual bruising and swelling.

Nursing, Allied Health, and Interprofessional Team Monitoring

Close follow-up during the initial post-operative period, either by a wound care nurse and/or clinician experienced in the post-operative care of lip implants, should monitor the patient for possible complications including bleeding, bruising, or infection. The nurses should work with the surgeon and an open line of communication should be present. The nurses should assist with patient education, monitoring, and follow-up care. [Level 5]