Augmentation of the infraorbital rim in orthognathic surgery

Abstract

Mid-face augmentation via a Le Fort I osteotomy is a commonly performed operation. Advancement of the upper jaw and associated structures (nose, lower cheek areas) can certainly improve function as well as facial aesthetics and harmony. Often, in patients with severe mid-face deficiency, hypoplasia of the maxilla extends all the way up to the infraorbital rims. The receding infraorbital rim contributes to the negative vector of the globes. In patients with this level of mid-face hypoplasia, while advancing the maxilla at the Le Fort I level satisfies all of the requirements for orthognathic surgery, the deficient infraorbital rim remains unchanged and can actually accentuate the negative vector of the globes. This article explains our approach in augmentation of the deficient infraorbital rim using alloplastic silicone implants at the time of a Le Fort I osteotomy.

Hypoplasia of the maxilla can often contribute to an angle class III malocclusion. Patients with this type of skeletal deformity exhibit specific manifestations such as deficiency of the mid-facial soft tissue, prominent nasolabial folds, acute nasolabial angles, and shortened upper lip heights. This appearance is due to the lack of appropriate anteroposterior (AP) projection of the maxilla. When examined closely, many of these patients will also exhibit a marked deficiency of the infraorbital rims. This should not come as a surprise since the infraorbital rims are the cephalad extension of the maxillary bone; a maxilla deficient at the Le Fort I level can certainly be deficient at the infraorbital rim component as well. Deficiency of the bony infraorbital rims are the primary cause of the “Negative” vector appearance of the globes.

As described by Pessa et al. and others, a negative vector occurs when the most anterior (convex) projection of the globes extends beyond the most anterior projection of the infraorbital region on a sagittal plane . Patients with a negative vector can exhibit mild scleral show, prolapse of lower lid fat pads and prominence nasojugal folds ( Fig. 1 ).

Fig. 1
Negative vector of the globe. Note position of the infra-orbital rim compared to the globe.

During a Le Fort I osteotomy, the maxilla can be advanced in order to address an AP deficiency. The osteotomy is performed along the pyriform rims and extends posteriorly into the pterygomaxillary regions. Some clinicians advocate modifying the osteotomy in order to encompass a more superior aspect of the maxilla during the AP advancement (high Le Fort I, quadrangular Le Fort I). However, the location of the infraorbital foramen dictates how “high” a Le Fort I osteotomy can be performed. In patients with a negative vector and maxillary deficiency, the deficiency of the infraorbital rims is actually located above the infraorbital foramen, thereby obviating the potential benefits of a modified Le Fort I osteotomy. Terino , in 2005, described the specific aspects of the cheek/infraorbital complex that can be surgically enhanced with alloplastic augmentation . Others have advocated augmentation of other parts of the mid-face with alloplastic implants . Using this technique, we describe our approach in the augmentation of the deficient infraorbital rims using silicone implants at the time of a Le Fort I osteotomy.

Patient selection and surgical procedure

Pre-operative evaluation of the orthognathic surgery is performed as usual. Hall marks of maxillary AP deficiency such as a concave facial appearance, class III malocclusion, shortened upper lip, and prominent nasolabial folds are noted. Examination of the mid-face also includes a thorough evaluation of the lower lid/cheek complex, especially in the profile view. The presence of scleral show, prominent lower lid fat pads, and orientation of the globe compared with the infraorbital areas are accounted for. The patient is appropriately counseled on the presence of a negative vector and surgical options such as alloplastic silicone augmentation is discussed ( Fig. 2 ).

Fig. 2
Ideal position of the implant compared to the osteotomy plates.

Using appropriate sizers, a silicone implant designed to augment the deficient infraorbital rims is chosen. This implant must augment the entire infraorbital region around the infraorbital foramen corresponding to the area of greatest bony deficiency. It is usually advisable to choose a small or medium-sized implant in order to achieve harmony between the infraorbital rims and the lower aspect of the upper jaw, since the maxillary osteotomy will address the deficiency at the Le Fort I level.

At the completion of a standard Le Fort I osteotomy and application of fixation plates, soft tissue dissection is carried more superiorly in order to release the arcus marginalis of the lower lid. This dissection is then carried laterally along the body of the zygoma and inferiorly into the submasseteric space in order to allow the implant to lie passively within its pocket. The implant is then inserted and positioned as superiorly as possible to augment the entire length of the infraorbital rims. The implant is almost always modified in order to allow for the infraorbital neurovascular bundle. It is critical to position the implant as cephalad as possible; this typically involves removing a small “wedge” of the implant with scissors in order to accommodate the neurovascular bundle. The superior edge of the implant should be “flushed” with the superior aspect of the infraorbital rim ( Fig. 3 ). Failure to place the implant in this manner will inadvertently augment the mid-cheek region as opposed to the infraorbital rims, and can cause an excessively “cheeky” appearance. Once properly positioned, the implant is secured with titanium screws. Owing to the position of the Le Fort I osteotomy plates, it is not unusual that a portion of the silicone implant may actually sit on top of these plates. Closure of the incision sites is then completed.

Fig. 3
(A) Intraop photo; note modification of the implant around the neurovascular bundle. (B) Bird’s eye view following augmentation of the right side. Note difference in appearance between right and left sides.

Discussion

Mid-face deficiency is a common indication for orthognathic surgery. Often times, patients present with predictable facial features such as a class III malocclusion, concave profile, acute nasolabial angles, and short upper lip length. Since the growth deformity is often not limited to the dentate portion of the maxillary bone, it is not unusual to identify further deformities associated with maxillary hypoplasia such as scleral show, lower lid fat prolapse, and a negative orbital vector. This correlation has been confirmed previously . Traditional evaluation of the orthognathic patient may not reveal these deformities. Le Fort I osteotomy has been the workhorse in mid-face advancement since the 1970s. The operation is certainly predictable, safe, and usually without major complications. When performed for correction of AP vector deficiencies, it augments the lower aspect of the upper jaw, improves the nasolabial angle, enhances the soft tissue projection of the nasolabial region, and improves any malocclusion.

Modifications of the traditional Le Fort I osteotomy have been described in order to enhance the augmentation of the mid-face, especially along the nasojugal and infraorbital areas. These modifications include a “high” Le Fort I or a quadrangular Le Fort I. While there is no doubt that further augmentation of the mid-face can be achieved when performing a modified compared with a traditional Le Fort I osteotomy, enhancement of a deficient infraorbital rim is nearly impossible. A modified Le Fort I osteotomy is limited along its most cephalad margin by the location of the infraorbital foramen and its contents; extending the osteotomy above the foramen will sever the neurovascular bundle. A recessed infraorbital rim, the main cause of a negative vector of the orbit, remains recessed and hypoplastic as the body of the maxilla is advanced in an AP vector during a Le Fort I osteotomy. As the lower portion of the maxilla is advanced, the appearance of the hypoplastic infraorbital rim actually worsens, because of the larger AP discrepancy between the location of the orbital rims and the new location of the lower maxilla.

There are various methods available to augment a deficient infraorbital rim. Non-surgical modalities include use of dermal fillers. These fillers are readily available and easy to use; however, many are only temporary and require additional augmentation every few months. The cost associated with these fillers can also become substantial when one recognizes the accumulated cost of the fillers over time. The main advantage of dermal fillers is the absence of surgery and recovery. Other available options include use of alloplastic implants, or a modified Le Fort III osteotomy. There are inherent disadvantages of a modified Le Fort III osteotomy including potential morbidity, enhanced complexity, and increased length of hospital stay.

Regarding alloplastic augmentation, there are several different companies producing various types of mid-face implants (polyethylene, silicone, polytetrafluroethylene, etc.). Silicone alloplasts are the preferred implant for all three authors. Silicone is easy to handle, can be easily trimmed, and is stable. As long as the implant is immobile and placed subperiosteally, risks of bone resorption is eliminated. Most companies offer various implant sizers that can assist in the preoperative phase in the selection of the correct implant size. Sterile sizers can also be used intraoperatively to assist in choosing the correct implant size. Upon completion of the Le Fort I osteotomy and application of fixation plates, soft tissue dissection is more cephalad in order to release the arcus marginalis both medial and lateral to the infraorbital foramen. This dissection can alternatively be performed at the beginning of the Le Fort I osteotomy. Soft tissue dissection must also be performed laterally along the body of the zygoma and distal aspect of the zygomatic arch. Fibers of the masseter are also dissected off the zygoma in order to allow the implant to sit passively within its pocket. The implant is trimmed appropriately in order to accommodate the infraorbital neurovascular bundle. The implant should be situated as cephalad as possible so that the most superior aspect of the implant is flushed with the infraorbital rim. This position will allow for the most amount of augmentation. The implant is secured using titanium screws. Often, the implant will actually sit on top of the osteotomy plates. Symmetry between both sides is then confirmed and the incision is closed in usual manner. All authors routinely keep patients on 5 days of systemic antibiotics (broad spectrum antibiotics with specificity against oral and sinus flora) after placement of silicone implants.

In conclusion, augmentation of the deficient infraorbital rim in patients with class III malocclusion is often ignored during routine orthognathic surgery. Patients with maxillary hypoplasia in the AP vector typically have a negative vector of the globes as well. Enhancement of the deficient infraorbital rim using silicone implants at the time of a Le Fort I osteotomy is a versatile and simple procedure which certainly improves the overall patient aesthetics ( Figs 4 and 5 ).

Dec 14, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Augmentation of the infraorbital rim in orthognathic surgery
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