Changing the facial appearance with facial contouring surgery is popular, especially in East Asian countries where a square face is a common chief complaint. Mandibular angle reduction, malar reduction, genioplasty, and chin and body contouring surgery can be performed as independent or ancillary procedures during orthognathic surgery. Many techniques have been developed and different osteotomy designs have been proposed to enhance outcomes and minimize complication risks. Here, we review the surgical techniques and considerations for mandibular angle and malar reduction, the two most commonly performed contouring surgeries in East Asia to correct the square face.
Key points
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An oval facial contour is considered attractive in East Asia, and malar and gonial angle reduction is commonly sought by patients to achieve the oval facial look.
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Meticulous planning is critical in contouring surgeries to correct the square face. Preventing injury to adjacent structures and having a clear understanding of the postsurgical complications are essential.
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Potential complications of zygoma reduction include temporary sensory disturbance, cheek drooping, temporomandibular discomfort, and overcorrection or undercorrection.
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The position of the inferior alveolar nerve should be precisely noted in mandibular angle reduction. A palpable “secondary angle” or palpable masseter muscle attachments are potential concerns for patients.
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Application of three-dimensional surgical guides can enhance the accuracy of osteotomy line positioning and procedural safety.
Introduction
The facial shape of East Asians can be classified as round, square, or oval. Facial shape can influence an individual’s preferred fashion style, such as hairstyle and type of glasses. Among the facial forms, the oval type is regarded as more favorable for women than the square type. A prominent zygoma or angle is often associated with an intense or fierce image in East Asian countries. Similarly, a square face is regarded as more masculine than an oval one. In East Asian countries including Korea and China, women prefer oval and slender faces (“V-shape”), as these facial types are considered more feminine. On the contrary, dolichocephalic craniofacial patterns are common in Western countries, as are deficient zygomas. As such, malar augmentation is more popular than malar reduction in Western countries, whereas in East Asian countries, reduction malarplasty, gonial angle reduction, genioplasty, chin, or body contouring surgery are frequently performed, either as independent procedures or as adjuncts during orthognathic surgery to achieve an oval facial contour. These procedures target the different parts of the face that contribute to a square look; prominence of the mandibular angle is influenced by the gonial angle and intergonial width, and a strong mandibular angle and the masseter muscles attenuate the malar prominence and give the face a squarer shape.
The current report focuses on the two most popular osseous contouring surgeries—reduction malarplasty and mandibular angle reduction. Many techniques have been developed, and different osteotomy designs have been proposed to enhance outcomes and to minimize potential complications. Meticulous planning is especially important in osseous recontouring procedures to correct the square face type. Preventing injury to adjacent structures and having a clear understanding of the postsurgical complications are paramount. The purpose of this article is to review the surgical techniques and their considerations.
Preoperative evaluation and planning
Many patients can have soft tissue hypertrophy or atrophy, which together with the underlying osseous contours can influence their facial form. Evaluation of the square face should include a comprehensive examination of the midface, including the zygoma, masseter muscle, mandibular angle, and the vertical/horizontal position of the chin. Major features commonly seen in square-faced patients are (1) wide bilateral gonial width, (2) low gonial angle, (3) flat mandibular plane angle, (4) retrognathic appearance of the chin, and (5) short anterior face. In the context of mandibular form, the square face is usually described as a low gonial angle deformity, with the gonial angle smaller than 110° or 120°, and the mandibular plane angle was smaller than 20° or 30° ( Fig. 1 ).
When considering malarplasty, identifying key anatomic landmarks on photographs and three-dimensional computed tomography (3D-CT) is important. Cephalometric landmarks for evaluation of the zygoma are limited, and cephalometric norms have not yet been established. As such, subjective opinions or impressions from patient interviews are also important to complement the surgeon’s impressions and clinical judgment. A key landmark when assessing malar form is the most prominent malar point (MP) on the soft tissue, which usually lies in the posterior-superior quadrant of the intersection of two lines, called Hinderer’s lines: (1) the line from the lateral canthus (Lc) to the lateral commissure and (2) the line from the superior aspect of the tragus to the alar base of nose. According to Wilkinson, MP is located just distal to the Lc on a point one-third distance from Lc to the mandibular inferior border. The facial width between the Lc, MP on both sides, and the most lateral point of the malar area (Zy) on both sides on the frontal view should be assessed. It should be noted that the MP and Zy do not always coincide ( Fig. 2 ).
Reduction malarplasty directly influences the position of the MP, so appropriate positioning of the MP must be determined before surgery to determine the degree of zygomatic bone repositioning and volume reduction. When the MP is repositioned, the point is mobilized medially or posteriorly. Occasionally, patients with normal malar projections can appear to have relatively prominent projections because of depressions in the frontal or cheek regions. In such cases, soft tissue contouring of these areas must be performed instead of malar reduction. In addition to changing the position of the MP, malarplasty can change the lateral prominence of the zygomatic arch. When the zygomatic arch is prominent, it can be rotated inward to decrease the lateral projection.
When planning mandibular recontouring, angle reduction is efficient for correcting mild to moderately prominent mandibular angles. However, in patients with a wide intergonial width, a low gonial angle and a flat mandibular plane at the same time, a long-curved osteotomy and a mandibular outer cortex splitting osteotomy are required. In patients with retrognathic or prognathic chins, the correction of skeletal problems using orthognathic surgery or genioplasty is necessary in combination with angle reduction. ,
Because of the multifactorial nature of the etiology of the square face, for some patients, multiple surgical techniques are required to correct these problems. Because of the irreversible nature of reductive facial recontouring procedures, thorough patient communication is paramount.
Reduction malarplasty
Surgical Technique
As Onizuka and colleagues first reported bony shaving of the malar body via an intraoral approach, numerous surgeons have reported a variety of techniques for reduction malarplasty. The design of the osteotomy is largely divided into zygoma shaving, I-shaped osteotomy, L-shaped osteotomy, , , and their modifications. , , , Shaving the outer cortex of the zygoma with a bur (without zygoma osteotomy) cannot decrease the bizygomatic distance. In addition, it is difficult to maintain malar symmetry or a natural malar contours with this technique. Therefore, the clinical use of zygoma shaving is limited.
The intraoral approach is now the standard procedure to expose the anterior zygomatic body. To perform the osteotomy at the posterior zygomatic arch, coronal, preauricular, , , , , sideburn, , , , , , , temporal, and intraoral-only approaches have been used (with or without , , , , , , , endoscopy). Currently, the intraoral with or without sideburn approaches are gaining popularity. In these procedures, the osteotomized zygoma is repositioned without fixation , , , , or with anterior/posterior fixation. , , , , , , , , , The most popular fixation is miniplate fixation at the zygomatico-maxillary osteotomy site. The approaches can be determined by the surgeon’s preference and surgical experience. The types of osteotomies and the approaches used are summarized in Table 1 .
| Design of Osteotomy Line | Approach | Fixation Method |
|---|---|---|
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a Ant, zygomatico-maxillary buttress; post, posterior aspect of zygomatic arch.
Recent studies have more frequently used the L-shaped malarplasty than the I-shaped osteotomy. The major advantage of L-shaped osteotomy is that the location of the osteotomy lies in the anterior region of the zygomaxillary suture region and is easy to access during fixation of the osteotomized segments. Another advantage of L-shaped osteotomy is that the most prominent aspect of the zygoma is included in the site of bone reduction in L-shaped osteotomy. A comparison of the two techniques is presented in Fig. 3 and Table 2 .
| I-Shaped Osteotomy , | L-Shaped Osteotomy , | |
|---|---|---|
| Outline of osteotomy | Anterior cut: vertical I-shaped cut Posterior cut: zygomatic arch cut Mobilize and displace the zygoma antero-medially; interosseous fixation |
Anterior cut: oblique (long) + vertical (short) Posterior cut: zygomatic arch cut Mobilize and displace the zygoma antero-medially; interosseous fixation |
| Indications | Wide zygomatic arch and lateral protrusion of the zygomatic body (when the zygomatic body is not prominent) | Protrusion of the zygomatic body and arch (serious protrusion of the anterior part of the arch exists) |
| Effects | Narrowing of the wide zygomatic arches Reduce the anterior protrusion of the zygomatic body |
Large amount of bone removal Significant medial reduction can be achieved |
| Precautions | Possible bulging of the most prominent part of the zygomatic arch even after surgery | More infraorbital reflection Possibility of inferior displacement (needs rigid internal fixation) |
Surgical Steps for L-Shaped Osteotomy
Reduction malarplasty is a blind approach with limited visualization. The surgical steps of L-shaped osteotomy for malar reduction are as follows:
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3D planning and simulation:
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Using cone beam computed tomography (CBCT) data, 3D surgical planning is performed to simulate the amount of bone volume reduction and the direction and magnitude of the mobilized segment ( Fig. 4 ).
Fig. 4 Surgical design for the L-shaped osteotomy. Osteotomy design and demarcation of amount of bone removal ( A ), before ( B ), and after ( C ) the reduction malarplasty from the lateral (upper), and submentovertical views (lower).
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Mucogingival incision:
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An incision is made on the buccal sulcus from the canine to the molar.
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Subperiosteal reflection:
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Mucoperiosteal reflection is carried out to the infraorbital foramen, zygomatic body, maxilla anterior wall, posterior to anterior part of the zygomatic arch, and superiorly to the junction of the lateral orbital rim and the zygomatic arch.
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Oblique osteotomy:
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Two oblique osteotomies start from the junction of the lateral orbital rim and the zygomatic arch.
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The line extends anterio-medially to a point 5 mm inferior to the infraorbital foramen. The distance between the two oblique osteotomy lines does not need to be large. The main purpose of this ostectomy is to facilitate the medialization of the zygoma body, rather than to allow volumetric reduction.
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Vertical osteotomy:
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The vertical osteotomy line (the short limb of the L-osteotomy) is located near the zygomaticomaxillary suture, nearly at a right angle to the oblique osteotomy line. The osteotomized segment of zygomatic bone is then removed.
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Zygomatic arch osteotomy:
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A preauricular sideburn incision, 1 cm in length, is made 20 mm anterior to the tragus. The periosteum above the zygomatic arch is reached using blunt dissection. Zygomatic arch osteotomy is performed anterior to the anterior border of the articular tubercle.
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The periosteum of the inner and outer sides of the osteotomy site is reflected, and the reciprocating saw is used from the inner side to the outer side to prevent damage to the neurovascular structures.
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Mobilization and fixation:
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After confirming the mobilization of the osteotomized zygoma, the segment is fixated in the planned position with a plate and screws, anteriorly with a miniplate, posteriorly with a microplate, or without fixation.
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Smoothening of bony step:
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The residual bony step is smoothened with a bur.
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Complications in Reduction Malarplasty and Their Managements
Although malarplasty is a safe procedure when performed by experienced surgeons, it carries the risk of many complications compared with other surgical procedures. One major postoperative complication is zygomatic nonunion. To correct this, a coronal approach is required to access the nonunion site to remove fibrotic scar tissue and to achieve bony contact after mobilization of the segment. If there is a large bony gap, bone grafting should be considered.
Postoperative trismus or temporomandibular joint problems commonly occur after surgery. This is mainly attributed to malunion of the zygoma, displacement of the zygomatic arch, rotation of the zygoma, or floating zygoma from fixation failure. These malunions are also accompanied by cheek ptosis and/or malar depression. Repositioning of the displaced zygomatic complex must be performed via a coronal approach. For trismus after surgery, active mouth-opening exercises are recommended after 2 to 3 weeks following surgery.
Cheek drooping or sagging can be seen when there is inferior displacement and external rotation of the mobilized zygomatic complex ( Fig. 5 ). As the traction force of the masseter muscle is strong, osseous fixation must be sufficiently strong to resist the masseter muscle force during mastication. , It has been suggested that high-level fixation on the superior region of the zygomatic bone is favorable to low-level fixation near the zygomatico-maxillary buttress to prevent malunion or nonunion caused by strong masseter muscle action. Other complications include undercorrection or overcorrection and postsurgical asymmetry, which can be corrected by reoperation or a separate secondary corrective procedure. Complications and management after malarplasty are summarized in Table 3 .
