Course of surgery for facial implant insertion

It is important to understand that in order to adapt to a narrow face or thin skin, the size and thickness of standard-shaped and sized implants will have to be reduced. Since all faces are different, it is important to take it as a rule that implants require modification. Therefore, the surgeon must prepare all expected designs, shapes and materials and be prepared to improvise an implant change. The absence of the correct implant for a specific patient can lead to an inferior result.

The day before the surgery, the patient begins taking a broad-spectrum antibiotic, which will be continued for up to 5 days after the surgery. Immediately before the procedure, an antibiotic and dexamethasone are administered intravenously. The areas of the proposed augmentation are marked with the patient in an upright position. This is the initial outline that is drawn on the skin, and then the patient is told that the final definition of the implant will be made to match the surgeon's and the patient's ideas about its shape, size and position.

General surgical technique for facial implantation

The basic principles of augmentation in the midface, zygomatic eminence, anterior jaw or nasal area are identical. The final overall contour of the face will be determined by the shape, size and placement of the implant.

Surgical technique for augmentation in the lower jaw area

• Anterior mandibular implants

Access to the anterior mandibular space is achieved either intraorally or externally. In the latter case, a 1-1.5 cm incision is made in the submental fold. The advantages of the external approach are that it avoids contamination by oral bacteria; it allows direct access to the inferior border of the mandibular bone, where there is a strong cortical layer; it does not require strong stretching of the mental nerves; and it allows fixation of the implant to the periosteum along the inferior border of the bone with simple sutures. This helps to prevent lateral or vertical displacement. The relative advantage of the intraoral approach is that it leaves no scar. Access is achieved through a transverse mucosal incision. The mentalis muscle is divided vertically along the median suture, without transecting its belly and attachments to the bone. This median incision provides adequate access downward to the bone of the central part of the chin and is not accompanied by weakening of the muscle that would occur in the case of transection. Lateral separation requires isolation and retraction of the mental nerves.

The basic rules for a safe and accurate mandibular corrective procedure are as follows. Separation should be along the bone. Subperiosteal placement of implants ensures their tight fixation to the bone. A tight periosteal attachment along the anteroinferior border of the jaw is present in the area of origin of the anterior mental ligament, which defines the anterior cheek groove at the bottom of the marionette fold that occurs with age. It is often necessary to dissect this ligamentous attachment in order to continue separation along the lower part of the mandible. Separation of this space should extend sufficiently to comfortably accommodate the prosthesis. Sharp separation can be used in the center, but only blunt dissection should be performed around the nerves and adjacent soft tissues. The mental nerve must be preserved. For safety, tissue around the mental foramen is pressed with the non-working hand, which helps to guide the elevator away from the nerve and along the lower border of the jaw. Careful hemostasis is necessary to ensure accurate visualization, dissection and proper placement of the implant, as well as to prevent postoperative hematoma or seroma.

A 4 mm Joseph periosteal elevator is used to dissect along the inferior border of the jaw. When the pocket is large enough, one arm of the implant is inserted into the corresponding lateral portion of the pocket and then flexed to bring the other arm to the opposite side of the pocket. The implant is seated in place. If the implant material is not flexible, either a larger incision is required or the surgery is performed through an intraoral incision. Implants that reach the mid-lateral or parasymphyseal area provide anterior expansion of the lower third of the face. The average central projection needed is 6-9 mm for men and 4-7 mm for women. Occasionally, in patients with severe microgenia, implants providing 10-12 mm or more projection may be needed to create a normal profile and a wider jawline.

• Implants for the angle of the lower jaw

The angle of the mandible is accessed through a 2-3 cm mucosal incision in the retromolar triangle. This provides a direct approach to the angle of the mandible. Dissection is performed across the bone and under the masseter muscle, separating the periosteum upwards along the ramus and then anteriorly along the body of the bone. A curved (90°) dissector is used to separate the periosteum along the posterior aspect of the angle and the ramus of the mandible. This allows for precise placement of the implants, which are specially designed to match the posterior bony margin of the ascending ramus and better contour the angle of the mandible. The implants are fixed with titanium screws.

Surgical technique for correction of cheekbones and midface contour

The primary method of access to the tissues of the malar region and midface is intraoral. Other approaches include subciliary (in combination with lower eyelid surgery), transconjunctival, rhytidectomy, temporozygomatic, and coronal.

Intraoral access

The intraoral approach is the most common and preferred approach for insertion of most midface implants, with the exception of implants for correction of gutter deformity (type V). After infiltration of the anesthetic solution, a 1-cm incision is made through the mucosa and directed toward the bone in an obliquely vertical direction above the buccal-gingival line and over the lateral support. Since the mucosa is stretchable and allows complete inspection of the midface structures, a long incision through the mucosa and submucosa is unnecessary and even inconvenient. The incision should be made high enough to leave a minimum of 1 cm of mucosal gingival cuff. If the patient wears dentures, the incision should be placed above the superior border of the denture. The dentures can be left in place postoperatively, which in our experience does not lead to implant dislocation or increase the complication rate. A wide Tessier-type elevator (approximately 10 mm wide) is directed through the incision onto the bone in the same direction as the incision. The wide elevator increases the safety of the dissection and is relatively easy to work with under the periosteum. By working the elevator directly along the bone, the soft tissue is dissected obliquely upward from the zygomatic process of the maxilla and the zygomatic eminence. The elevator is advanced along the inferior border of the zygomatic eminence and the zygomatic arch. The free hand on the outside helps to guide the elevator in the desired direction. In routine correction of the zygomatic and infrazygomatic areas, no attempt is made to visualize or isolate the infraorbital nerve unless an implant is to be placed in this area. If necessary, the infraorbital nerve can be easily visualized more medially. The infrazygomatic cavity is created by dissecting the soft tissue inferiorly, below the zygomatic bone and above the masseter muscle. The correct plane of dissection can be recognized by visualizing the white shiny fibers of the masseter tendon. It is important to note that these masseter attachments are not transected and are left completely intact to provide a supporting framework on which the implant can rest. As we move posteriorly along the zygomatic arch, the space becomes tighter and is not as easily widened as in the medial part. However, some of the space can be opened by gently separating and elevating the tissues with a strong blunt periosteal elevator. It is extremely important that the dissection be wide enough to allow the implant to be passively positioned in the pocket. A pocket that is too small will push the implant to the opposite side, causing it to dislocate or dislocate. It has been shown that, in the normal situation, the pocket collapses and most of the space around the implant is closed within 24-48 hours after surgery. Accurate selection of the implant is facilitated by observing the changes induced by placing various "calibrators" in the pocket.

The final placement of the implant should follow the outer contours of the defect area outlined on the face before surgery. In subzygomatic augmentation, the implant may be placed under the zygomatic bone and zygomatic arch, over the masseter tendon; it may cover both bone and tendon. Larger concha-type zygomatic implants are placed primarily on bone with a large superolateral offset and may partially extend into the subzygomatic space. A combined implant will occupy both areas. Any implant placed in patients with significant facial asymmetry, thin skin, or very prominent bony protrusions may require modification by reducing the thickness or length to prevent contouring. One of the advantages of silicone elastomer implants is their flexibility, allowing the implants to be pushed through small holes and then restored to the volume and shape of the pockets created. This eliminates the need for large incisions required to insert more rigid implants and allows for multiple implant replacements as sizes and configurations are selected.

• Facial asymmetry

The most difficult task in improving facial contours is the correction of facial asymmetry. A detailed discussion of this problem is required during the preoperative consultation, since most patients are usually unaware of the qualitative and quantitative expression of their facial asymmetry. Close attention to detail is required to identify, understand, and select the type of correction of spatial disturbances. It is not uncommon to find adequate malar development and well-supported soft tissue cushions with a satisfactory external contour on one side of the face and an underdeveloped malar eminence with relative soft tissue atrophy and significant skin wrinkles on the other side. In such cases, it is necessary to adequately select the available standard implants and prepare for their individual adjustment to eliminate the contour differences on both sides. Unusual asymmetries may also require the use of different implants on each side or individual spacers cut from a silicone block and sutured to the posterior surface of the implant to increase the protrusion of one of the segments.

• Implant fixation

Once an implant has been placed, it usually requires fixation. This can be done in a number of ways. Fixation with internal sutures requires an adjacent stable segment of periosteum or tendon structure to which the implant will be sutured. Stainless steel wire or titanium screws can also be used. There are two methods for external fixation of implants. The indirect lateral fixation technique involves the use of 2-0 Ethilon sutures on large Keith needles, which are threaded through the end of the implant. The needles are then inserted from the inside through the pocket in a posterosuperior direction and exit through the skin posterior to the hairline at the temple. The sutures are tightened on a bolster, creating tension at the end of the implant. This technique is more suitable for zygomatic implants. The direct external fixation technique is often used in patients with severe asymmetry or when subzygomatic or combined implants are used. In these situations, the direct external fixation technique prevents slippage in the early postoperative period. In this technique, the implants are positioned in direct correspondence with the marks on the skin that coincide with the two most medial fenestrations in the implant. The symmetry of the position of both implants is checked by measuring the distance from the midline to the right and left medial marks. The implants are then removed and placed on the skin so that the medial fenestrations coincide with the corresponding marks. The position of the lateral part of the implant is determined by a second mark placed in correspondence with the adjacent fenestration in the implant. A thread with straight 2.5-cm needles at each end is then passed through the two medial fenestrations of the implant in a posterior-to-anterior direction. The needles are inserted from the inside into the anterior wall of the pocket, passed perpendicularly through the skin and punctured through the corresponding marks. The implant is inserted into the pocket using this thread and fixed in place by tying the threads on rollers consisting of two gauze balls.

Under-lash access (for lower eyelid surgery)

Inserting a large implant through the subciliary approach is much more difficult. However, this approach is preferred for inserting a "gutter implant". The blepharoplasty-like approach may be acceptable for isolated cheekbone augmentation, when a smaller malar implant is required in zone 1 or 2 to achieve high cheekbones. The advantages of the subciliary approach are the absence of contamination with oral flora and soft tissue support from below, which reduces the likelihood of implant ptosis. However, in the presence of a weak cartilaginous base of the eyelids, this technique may force the formation of ectropion.

Transconjunctival approach

The transconjunctival approach is used to insert implants into the midface, but it also requires division of the lateral canthal tendon. This necessitates subsequent canthoplasty, which carries the risk of lower eyelid asymmetry.

Rhytidectomy approach

The zygomatic space can be safely entered through zone I. Penetration of the subcutaneous musculoaponeurotic system (SMAS) is medial to the zygomatic eminence, and then the bone is bluntly reached. There are no important nerve branches in this area. The zygomatic pocket is created primarily by retrograde dissection. However, implant insertion through this approach may encounter technical difficulties in dissecting and separating the SMAS, which limits the use of extended implants.

Zygomatic/temporal and coronal approaches

Subperiosteal facelift techniques provide rapid access to the malar region. However, endoscopic approaches generally limit the exposure and visualization needed to work with larger implants.