The use of expanded polytetrafluoroethylene in depressed deformities of the face

Introduction

Contour enhancements of the face constitute an important aspect of facial plastic surgeries for cosmetic, as well as traumatic, congenital, and extirpative defect corrections (1). There are various options to consider for the reconstruction of a facial depressed deformity depending on whether the underlying defect is a skeletal or a soft tissue depression, including autologous tissue grafts, allogenic tissue grafts and alloplastic materials.

Autologous tissues, such as grafted adipose tissue (lipofilling), are thought to produce a more natural reconstruction of the contour of the face, but they are highly invasive with significant donor site morbidity and have drawbacks including limited availability, limited moldability, and unpredictable resorption (2). These disadvantages constrict their clinical use. Various alloplastic materials have been used in facial cosmetic and reconstructive surgery. The material should have good biocompatibility, be easy to remodel at the operating table, maintain its desired form and consistency in situ, and be inert in body tissue (3). The most commonly used materials in clinical practice include silicone, Gore-Tex, medpore, and expanded polytetrafluoroethylene (ePTFE) (1,2). Silicone implants lack the ability for vascularization, promote thick capsule formation, cause resorption of the underlying bone, and display a tendency for the implant to shift or extrude over a long period of time. With Gore-tex the risk of infection, seroma formation, and shifting from optimal place increases. Medpor has good biocompatiblility, but due to its characteristic of stiffness, it is mainly used on the bone reconstruction and cannot be used in the soft tissue.

W.L. Gore and Associates, Inc. first produced ePTFE in 1969 (4,5). The material was first used in 1982 to reconstruct soft-tissue deficiencies. Since then, ePTFE has been used safely and effectively in the human body for various applications in vascular and cosmetic surgery. In cosmetic surgery, ePTFE was often used for facial wrinkles, and for chin and nasal augmentation.

In the present study, the ePTFE was used for large-area facial depressed deformities. The results showed that, ePTFE constituted a viable alternative treatment for facial depressed deformity.

Patients and methods

Patient selection

In theory, any healthy patient with a facial depressed deformity is suitable for ePTFE implantation. However, to obtain a more satisfactory outcome for the surgeon and the patient, patient selection should be deliberate. An ePTFE implant is more suitable for patients with thick skin and subdermal tissue, and especially for patients who do not want to undergo a more invasive surgery of free-flap transfer. ePTFE is a long-lasting solid implant that is palpable and visible on animation when it is implanted in thin subdermal tissue.

In the present study, 31 ePTFE implants were used for facial augmentation in 26 patients (12 women, 14 men) between September 2008 and January 2014. The patient age range was 17–45 years (mean age 23.2 years). Indications for the augmentation procedure were congenital malformations, post-traumatic defects, and reconstruction after tumor surgery. Of the 26 patients, diagnoses included stable hemifacial atrophy (3 cases), craniofacial microsomia (13 cases), bony depression after trauma (8 cases), and other unclear reasons for soft tissue atrophy (2 cases). The implants were used for augmentation in the nasal/paranasal area, zygomatico-orbital area, and chin and mandibular area. The postoperative follow-up periods ranged from 6 to 18 months (average 9 months).

Surgical technique

The procedures were performed under local anesthesia (a solution of 0.5% lidocaine with 1:200,000 epinephrine). The depressed deformity area was marked with methylene blue, and an ePTFE implant with the proper thickness, was trimmed on the edges for a polished smooth transition effect.

For the frontal area, the surgeon first marked the region to be treated with an indelible marker. If the patient had displayed a strong frontalis movement during the pre-operatory examination, the botulinum toxin was injected 1 week before the implanting procedure. After marking, a solution of 0.5% lidocaine and 1:200,000 epinephrine was infiltrated along the planned dissection area and the two supraorbital ridges to block the supratrochlear and supraorbital nerves. A no. 15 Bard-Parker blade (Aspen Surgical Products, Inc., Chicago, IL, USA) was used to make an incision along the 5-cm in length marked line behind the anterior hairline down through the level of the periosteum. A subperiosteal dissection was carefully made, inferiorly to the level of the superior orbital rim and laterally to the temporal ridge, taking care not to tear the periosteum or cross over the temporal fusion line, and carefully avoiding the supraorbital neurovascular bundles. The range of dissection extended into normal tissue 0.5–1 cm beyond the junctional transition zone of the defect. The trimmed ePTFE implant was inserted into the subperiosteal pocket with utmost precision and the edges were inspected carefully to confirm that there was no buckling or folding. Then, the incision was sutured.

For the cheek, temporal, and mandibular areas, the procedure was almost the same except for the obvious differences regarding the tissue plane for implanting and the access sites. For patients with a recipient site on the cheek and zygomatic areas, a preauricular incision was made to create a pocket between the subcutaneous tissue and the superficial musculoaponeurotic system (SMAS). For the temporal and frontal depressed deformities, an incision behind the hairline was selected, the dissected space lay between the deep and superficial temporal fascias, and the utmost care was taken to preserve the facial nerve intact. For augmentation of the mandibular area, a submental incision was made to access the implantation site (Fig. 1).

Figure 1. Diagram of incisions for expanded polytetrafluoroethylene implanting.

Results

In order to treat facial depression, 31 ePTFE were implanted into the temporal areas (3 implants), cheek areas (5 implants), zygomatic areas (10 implants), mandibular areas (8 implants) and frontal areas (5 implants) in 26 patients.

No major complications occurred during the follow-up of the 26 patients who had ePTFE implants inserted for varied depressed deformities in the frontal, temporal, zygomatic, and mandibular areas. There were no cases of infection, implant exposure, delayed hematoma, or seroma. Minor complications, such as immediate postoperative hematoma, visible or palpable lateral border, asymmetries of shape, visible scars, or hair loss were also rare. There was 1 patient (3.8%) with an under-corrected depressed contour, while the remaining 25 patients were satisfied with the outcomes (satisfaction rate, 96.2%) (Figs. 2 and 3).

Figure 2. Expanded polytetrafluoroethylene implant augmentation, via preauricular incision, in a 36-year-old man with a major depressed deformity of the right cheek. Left, preoperatively; right, 7 months postoperatively.

Figure 3. Expanded polytetrafluoroethylene material augmentation, via an incision behind the temporal hairline, in a 23-year-old man with a depressed deformity of left temporal area. Left, preoperatively; right, 1 year postoperatively.

Discussion

ePTFE is a woven form of PTFE that creates a mesh-like structure. It is flexible, soft and strong, non-toxic, biocompatible, and not water-soluble. It has been reported that although the ePTFE soft-tissue patch is a porous material (average pore size is 22 µm), it does not appear to allow extensive fibrous tissue ingrowth, as do other porous alloplastic materials (4,5). Previous findings have shown that the pores of ePTFE provide a lattice for incorporating connective tissue (6). The phenomenon of little to no tissue adhesion allows for easy removal in case of complication or if the patient is not satisfied with the augmentation result. The level of tissue reaction to ePTFE is little, and previous reports confirm fibrotic capsules are minimal (1–3,5–8). Scant and focal chronic inflammatory cell reactions to ePTFE material may be explained by micro-motion at the tissue-implant interface, contamination, or reaction to the material configuration. However, the implant material itself does not appear to be a direct stimulus for inflammation, unlike Proplast, another form of polytetrafluoroethylene, which elicits an intense and ongoing inflammatory cell reaction that does not subside but rather markedly increases over time (4).

Various methods for correcting facial depressed deformities have been described in the literature (6,9). Silicone and Gore-Tex are the most widely used implant materials for skeletal augmentation. However, certain intrinsic properties such as stiffness and molding difficulty, hinder their use in soft tissue augmentation. If the patient has a thin skin texture or the implant is placed in a dynamic expression rich area, the borders of the hard implant can be identified or palpated. Fat injections or autologous fat grafting for facial contouring are one of the most frequently employed methods as they are easy to perform and involve a relatively minor invasive procedure. However, autologous fat grafting has the critical pitfall of unpredictable resorption over time and the risk of uneven distribution of fat throughout the area that the surgeon wants to modify.

During the procedure, attention should be paid to the implanting tissue plane and implanting region. As mentioned earlier, aside from frontal and temporal regions, ePTFEs can be inserted into the tissue plane between the SMAS and subcutaneous tissue. Particularly important for such a procedure is to ensure the skin is sufficiently thick to conceal the traces of the edges of the ePTFE. It is not recommended to implant ePTFE materials in the regions of lips and nasolabial folds, however, as there is an increased risk of a discomforting firm or stiff feeling (10).

Biotolerability is defined as the ability of a material to reside in the body for long periods of time with only low degrees of inflammatory reaction (11). Various factors affect biotolerability, including the biomaterial itself and the implanting procedure. Bacterial infections and repeated frictions in the implantation regions are important contributing factors for inflammatory reactions. Thus, to increase biotolerability, we refined our operational procedures to decrease the possibility for inflammatory reactions. We stringently adhered to the principles of aseptic technique, avoided frequent placing in and removal from the dissected pocket, suturing the incision tightly away from potentially invading bacteria.

In conclusion, ePTFE is biocompatible and can be well tolerated by the host. Through mature preoperative planning and skillful manipulation, ePTFE can yield a good outcome. Aside from lipofilling and a free-flap transfer, ePTFE constitutes a viable alternative to consider for the treatment of depressed deformities of the face.

Acknowledgements

The present study was supported by the Chongqing Science and Technology Commission (Cstc2013kjrc-qnrc10003).

References