A 26-year-old woman with congenital bilateral prominent zygoma underwent surgery under general anesthesia. Osteotomies on the zygomatic body were done using 2 saw blades fixed 5 mm apart. The patient recovered well after the operation without any complications. Both the patient and the doctor were satisfied with the result in the one-and-a-half year of follow-up period (Fig. 5).
A 44-year-old woman with prominent zygomatic bones and mandibular angles accepted the L-shaped osteotomy zygoma reduction. Her overprotruding zygoma was more obvious than the prominent mandibular angle. Osteotomies on the zygoma body were done using 2 saw blades fixed 3 mm apart, and the bone fragments were removed. No serious complications occurred and the zygoma was reduced effectively. The patient was satisfied with the results, but without the mandibular angle reduction, her prominent mandibular angle makes her facial profile a square shape (Fig. 6).
The approaches for zygoma reduction can be simply divided into 2 parts: the external approaches (such as the coronal incision, temporopreauricular incision, preauricular incision, etc) and the intraoral approach. The external approaches and the intraoral approach both have their own pros and cons.
The external approaches are endowed with good exposure but followed with visible scars, much bleeding and long operation time. Compared with the external approaches, the intraoral approach has no visible scars, little bleeding, and short operation time. It is associated, however, with some problems such as cheek drooping caused by a wide dissection, limited operative exposure in the area of the zygomatic arch, difficult fixation, and the possibility of facial nerve injury. Hence, we need to minimize the periosteal dissection, shorten the operative duration, and provide a postoperative elastic facial dressing to avoid the cheek drooping. The intraoral approach has been widely used as the most common method to reach the zygomatic body. However, to reach the posterior end of the zygomatic arch with the purpose of reducing the scar is not so easy. To overcome this defect, we use the method that reaches the posterior end of the zygomatic arch along the medial side of the arch. Hence, we are able to reach the zygomatic tubercle safely and simply even in a blind procedure without any nerve injury or serious cheek drooping.
The operating methods for malarplasty can mainly fall into the following: the zygoma reduction method with large burr to thin the zygomatic thickness, the infracture through greenstick fracture, and bone cutting.3
Shaving, however, as a single simple method of zygoma reduction, has not overcome the limitations. If the facial protrusion is only caused by the wide and large zygomatic arch, the zygoma reduction cannot be fully realized only with burring. Furthermore, we cannot avoid the cheek drooping if we use the intraoral approach because of the wide subperiosteal dissection.
The method of infracture is hard to control. We can also see that, if the greenstick fracture is carried out at the arch, the fragments in operation can only be moved to the inside; it is impossible to move backward or upward or downward. To get the best effect from surgery, it is necessary to move the protruding part of the zygoma to the inside, upward, and backward. Therefore, this method is not so satisfactory.
Because of the aforementioned reasons, there is no doubt that the bone cutting method is more effective. The zygoma reduction result of this method depends on the amount of the bone cutting. This facilitates the adjustment of the zygoma reduction and the movement of the fragments so that the best operating effect can be ensured through the best positioning. (The position of the osteotomy line and the moving direction of the protruding malar can be determined during the presurgery assessment.)
There are 2 designs of osteotomy for the zygomatic body: I-shaped osteotomy and L-shaped osteotomy. Baek et al4 described an I-shaped osteotomy by removal of the malar complex and contouring of the bone with replacement as a free bone graft. Although it is effective to reduce the facial width, the operation is hard to control and the bone graft has a high possibility to be absorbed. Meanwhile, the shape of the osteotomy line makes it easy for bone fragment displacement and the pulling of the masseter muscle will move the fragment downward. The L-shaped osteotomy can avoid the fragment displacement because the fragment is only removed between 2 L-shaped cuttings but from the inferior border so that, after osteotomy, if we fixate both sides of the osteotomy line, the masseter muscle cannot drag the fragment downward because of the countercheck of the inferior border. That is why we did not have cheek drooping cases in our follow-up period that still can be seen in other’s reports.5 Another operative method using an intraoral approach has been reported,6 but this method also required extensive subperiosteal dissection from the upper intraoral incision to the posterior area of the arch to approach the lateral aspect of the arch. Theoretically, facial nerve injury is possible during this procedure.7 Our method can solve this problem because we do zygoma reduction with L-shaped osteotomy by approaching the arch osteotomy point through the medial side. With our method, we do not require subperiosteal dissection because the osteotomy of the arch is from the inside out within the temporal fossa.
For the zygomatic arch, the most important thing is the osteotomy angle. The different angle leads to a different result. The horizontal cutting angle can only push the fragment inside, and it may cause the result to be less effective. We do osteotomy at the zygomatic arch using a new horizontal osteotomy with the reciprocating saw. Our method provides for the perfect movement of the fragment, making our horizontal osteotomy the most effective method. We can move the fragment backward and inside because we cut the arch horizontally with an angle of 20 degrees.
Another important thing that one needs to pay attention to is the height proportion of the zygoma and the mandibular angle. If the mandibular angle is not wide and large, the malarplasty alone can provide the adjustment to the facial profile; however, if the zygoma is protruding and the mandible angle is prominent simultaneously, the malarplasty alone may lead to a more obvious angle of the mandible.7–9 Therefore, for this kind of patient, the zygoma osteotomy should be synchronized with the mandibular angle reduction to satisfactorily improve the facial profile in one step and avoid the need for a second operation to adjust. Among the 114 cases of malarplasty mentioned previously, 87 of them received simultaneous mandible angle reduction, covering approximately 76 % of all the patients.
To sum up, using this method of an intraoral approach and L-shaped osteotomy with fixation can protect the nerves from damage during the operation and will leave no scars on the skin or the scalp. Also, especially important is the 20 degrees to horizontal angle from the inside to the outside osteotomy that can make the dissociated bone be easily moved inward and upward. This means the structure can be adjusted on the basis of the patients’ unique requirements that can lead to a perfect result after the operation. As a safe and effective method, it can reduce the incision, lower the surgery risk, mitigate patient pain, and shorten the operation time.
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Keywords:© 2014 by Mutaz B. Habal, MD.
Intraoral; approach; osteotomy; protruding; zygoma