Midface Restoration with Hand-Carved e-PTFE Orbital Rim Implants

Kenneth D. Steinsapir

This chapter provides details on a midface surgical technique that places a hand-carved expanded polytetrafluoroethylene (e-PTFE) implant on the orbital rim and malar face to replace lost bone volume at these locations. The implant is fixed to the orbital rim with titanium microscrews and serves as a fixation site for vertically lifted ptotic midface soft tissue reestablishing more youthful midface anatomic relationships. In reconstructive situations, the surgery is used to reestablish functionally appropriate anatomic relationships. Obviously this requires an invasive surgery. The method is discussed in a book on minimally invasive surgery because it accomplishes something that has proven elusive with less invasive methods. It should be noted that this surgery can and should be accomplished with just a 5 mm skin incision at the lateral canthus. A longer transconjunctival incision carried behind the lower eyelid and a flexible implant makes this surgery possible. As such, this technique has the virtue of creating an almost undetectable scar and achieving an even more important goal of creating a very powerful and natural midface restoration.

Anatomical Considerations

A youthful midface is full. It is filled by the malar fat pad, which in youth is firmly held in place by the zygomatic and orbitomalar osteocutaneous ligaments. This soft tissue is also supported by a properly projected orbital rim and malar face composed medially by the maxilla and laterally by the zygoma. The malar fat is a subcutaneous fat pad that is 6 to 8 mm thick and can be conceptualized as a base-up triangle that originates along the lower eyelid crease 4 to 6 mm below the lower eyelid margin.

The midface from a practical standpoint is the facial area around the lower eyelids that is neither improved by the lower facelift nor by the upper facelift. Anatomically, the midface is a triangular zone bound medially by the nose, laterally by a line that extends from the angle of the mouth to the inferior aspect of articular tubercale on the zygomatic arch, and superiorly by a line that extends from the medial canthus to the superior aspect of the articular tubercale on the zygomatic arch. As such, the midface includes the entire lower eyelid complex, the malar fat pad, the lip elevators, and the zygomatics major and minor.

Over time, the malar fat pad falls. Ptosis of the malar fat pad contributes to a prominent nasolabial fold. In the lower eyelid complex, malar fat pad ptosis contributes to the nasojugal or tear trough hollow under the eye. This hollow can also be exacerbated by a deep canine fossa. Aesthetically, patients are bothered by these anatomic changes including a related condition commonly referred to as “dark circles.” Functionally, midface ptosis and inadequate orbital rim projection contribute to inferior scleral show, entropion, ectropion, and adverse outcomes following a variety of lower eyelid surgeries.^1,2 The growing understanding of the importance of the midface is also forcing a reappraisal of the lower blepharoplasty.³

Many cosmetic surgeons embrace lower eyelid surgery as one of the best cosmetic procedures. However, in many cases it simply makes the tear trough hollow more evident. Something is clearly missing in our analysis of the problem. Herniation of orbital fat into the lower eyelid is at most a minor cause of the prominence of the inferior orbital fat pad. The most significant change is the long-term remodeling of the bony orbital rim and malar face. Studies have shown that the facial skeleton remodels during adulthood. The inferior orbital rim and malar face falls and retrudes. Not surprisingly, the next most important change is ptosis of the malar fat pad in association with laxity of the osteocutaneous ligaments of the midface, in particular, the orbitomalar ligament. These changes expose the inferior orbital fat. Lower blepharoplasty is surgery on an epiphenomenon.

The descent or absence of subcutaneous fat anterior to the orbicularis oculi muscle is responsible for the appearance of the dark circle. In youth, the leading edge of the malar fat pad originates anterior to the orbicularis oculi muscle and contributes to the fullness that defines the inferior aspect of the lower eyelid crease. Subcutaneous fat has a much higher light reflectivity than muscle. Light incident to the facial skin can be reflected, absorbed, or scattered. Light that is absorbed may be reflected, absorbed, or scattered by the deeper tissues. Where this light is scattered or absorbed less light is reflected back through the skin producing an area of darkness compared with areas where more of the light is reflected back out of the skin. The dark circle is an area of the lower eyelid that has little or no subcutaneous fat. Instead, light that is transmitted through the skin strikes the orbicularis oculi muscle where it is primarily absorbed by the muscle. In contrast, the adjacent cheek skin contains relatively abundant subcutaneous fat. Here the transmitted light is reflected back through the skin making the cheek look less dark than the dark circle. Midface surgery by lifting the subcutaneous fat back into the eyelid helps to decrease the appearance of the dark circle.

Our understanding of the soft tissue changes associated with midface ptosis has also changed with our increasing understanding of the midface superficial musculoaponeurotic system (SMAS). Recent studies by Lucarelli and coworkers have elucidated the role of orbitomalar ligament laxity in midface ptosis.4 Along the orbital rim the orbitomalar ligament is a well-defined facial condensation that extends through the orbicularis oculi to insert into the dermis.⁵ This ligament helps to support the malar fat pad. Malar fat pad ptosis is associated with laxity of this ligament. This laxity is superimposed on the bone changes noted above. These studies also demonstrate that the suborbicularis oculi fat (SOOF) is relatively fixed and as such does not contribute to midface ptosis. Therefore, approaches that emphasize the advancement of the SOOF over the entire cheek soft tissue mass are likely to be unsatisfactory.

Review of Prior Approaches

It could be argued that flattening the fullness in the lower eyelid is better than having the double convexity deformity described by Hamra.³ Certainly lower blepharoplasty does have a role as a compromise procedure in patients who are unwilling to have midface surgery. Our patients may be happy with an improvement or a changed appearance, but a critical surgeon will recognize that this approach does not restore “youthfulness” to the midface. It does nothing to address the remodeling of the orbital rim and malar face. It does not correct the descent of the malar fat pad. In fact, lower blepharoplasty wastes an important tissue volume represented by the anterior orbital fat.

Advocates of arcus marginalis release open the orbital septum and preserve and reposition the inferior anterior orbital fat along the external edge of the inferior orbital rim. Arcus marginalis release was first described in 1981 by Loeb who correctly understood that there was more going on in the midface than just herniation of orbital fat.^6,7 He noted that patients who underwent lower blepharoplasty failed to have improvement of the nasojugal groove. Rather, surgery seemed to worsen its appearance. He theorized that the ideal midface morphology was a flat surface essentially from the lower eyelid lashes into the cheek. To address the nasojugal groove, he proposed advancing the lower eyelid fat pads over the inferior orbital rim and onto the malar face to fill in the nasojugal groove. Hamra popularized the preservation of inferior orbital fat.^3,8 Revisiting Loeb’s concepts, he pointed out that with age there is an increasing skeletonization of the orbits and that a youthful midface is associated with soft contours and an absence of bone contours. Although arcus marginalis release provides a moderate improvement of the orbital rim soft tissue relationships, it is inadequate to replace the volume from the inferior rotation and retrusion of the bony malar face or the situation where there is an abnormally deep canine fossa. An anatomically correct approach is the replacement of the volume lost by bone remodeling and a vertical midface soft tissue lift. When these two factors are controlled, the advanced midface soft tissue meets the lower eyelid orbital fat in continuity to reestablish a more youthful midface contour.

Flowers was one of the first surgeons to address mid-face ptosis.⁹ He conceptualized the tear trough deformity to be the result of a soft tissue deficiency between the orbicularis oculi and the levator labii alequae nasi muscle in some and a static lack of bone projection in others. His surgical correction relied on the placement of a small comma-shaped silicone “tear trough” implant (Gore subcutaneous material, Implant Tech, Van Nuys, California). This implant has a notch to accommodate the infraoribtal neurovascular bundle and could be placed via an infraciliary incision or laterally through a facelift approach. Other authors have also described placing this implant via a transconjunctival approach.¹⁰ However, the Flowers implant provides a limited amount of increased orbital rim projection, which is not adequate for many individuals. Options for fixation of the implant are limited. It has been this author’s approach to suture the implant to the diaphanous arcus marginalis. Others have advocated direct vertical SOOF lifting with fixation to the arcus marginalis.^11,12 However, published reports of these methods provide no long-term follow-up to assure midface surgeons that the site is adequate for long-term tissue fixation. It is highly likely that the arcus marginalis is not adequate to support the weight of the midface. For these reasons, methods that rely on a superior lateral lift for elevating midface tissue, even though they do not provide an anatomically correct vector of support, are more popular.^13–15

The Goldberg implant produced from porous polyethylene (Porex Surgical, Newnan, Georgia) is another option for midface augmentation.10 This implant was developed as an alternative to split rib and calvarial onlay bone grafting as a means to increase the projection of the inferior and lateral orbital rim without the necessity of craniofacial midface advancement. It is thicker than the Flowers tear trough implant. The implant can be trimmed with difficulty and it is fixed to the bone with microscrews. The rigidly fixed implant can then be used as a fixation site for advanced soft tissue. Given the difficulty in carving this implant for individual patients and the desire to have a material that is softer and more elastic, an alternative material was sought for augmenting the malar face and orbital rim.

The material selected for orbital rim augmentation was e-PTFE reinforced sheets (W. L. Gore & Associates, Flagstaff, Arizona). This material is readily available and U.S. Food and Drug Administration (FDA) approved for deep augmentation in the face. It has been used clinically since 1971 as a vascular graft and has been used in millions of patients.^16,17

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