Aesth Plast Surg (2014) 38:1143–1150 DOI 10.1007/s00266-014-0405-4
ORIGINAL ARTICLE
CRANIOFACIAL/MAXILLOFACIAL
Zygomatic Arch Reduction and Malarplasty with Multiple Osteotomies: Its Geometric Considerations Fushun Ma • Shengjian Tang
Received: 6 March 2014 / Accepted: 28 August 2014 / Published online: 16 October 2014 Ó Springer Science+Business Media New York and International Society of Aesthetic Plastic Surgery 2014
Abstract Background The midfacial width is dominated by the lateral protruding degree of the zygomatic arch. The best way of narrowing the midface is to reduce the arch height and the arc length for patients with an overly curved lateral protruding zygomatic arch. The existing techniques for reduction malarplasty cannot change the degree of curvature of the zygomatic arch. We provide a new technique for efficient midfacial width reduction by multiple osteotomies at different sites on the zygomatic complex and bone resection at the most protruding middle part of the zygomatic arch. The amount of bone resection can be calculated with a simplified geometrical solution according to the desired reduction rate of the arch height. Methods A digitalized CT image was used to estimate the arch height and the length of bone for removal from the zygomatic arch. A specific piece of bone was removed from the most protruding point of each zygomatic arch. Greenstick fractures were made at the anterior and posterior roots of the zygomatic arch. The open arches were rotated inwardly until both ends met. Result The arch heights of 1,020 sides of the zygomatic arch were reduced in a range from 3 to 11 mm. All the reduced zygomatic arches were reunited properly and healed solidly. The overall satisfaction rate was high. Conclusion This technique reduces the width of the midface by changing the degree of curvature of the zygomatic arch. The simplified geometrical calculation solutions are F. Ma S. Tang (&) Plastic Surgery Hospital of Weifang Medical University, 288 Shenglidongjie Kuiwen, Weifang 261042, Shandong, China e-mail: [email protected] F. Ma e-mail: [email protected]
helpful in assuring the reunion of the zygomatic arch at a predesigned lower arc height level after a calculated shortening of the arc length. Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. Keywords Reduction malarplasty Zygoma Geometric evaluation Multiple osteotomies Zygomatic arch Midfacial width
Introduction Reduction malarplasty is a popular surgery among the Oriental population because patients want to make their wide midface narrower in order to achieve a slimmer look. There have been some surgical techniques for reduction malarplasty published such as chiseling and shaving down [1–3], L-shaped or boomerang osteotomy [4–9], tripod osteotomy [10, 11], posterior root osteotomy of the zygomatic arch [12–15], and anterior and posterior root osteotomies with zygomatic arch under tuck techniques [16–19]. The chiseling and shaving technique together with the L-shaped or boomerang technique mainly concentrate on reducing the size of the zygomatic bone or the anterior end of the zygomatic complex. The tripod and anterior or/ and posterior root osteotomy techniques aimed to reduce the zygomatic arch but in a limited degree because if the arch is pushed inward too much, for instance, more than the thickness of the arch, the bone ends will not meet. Above all no previous technique has tried to do the reduction malarplasty by making the overly curved zygomatic arch
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straighter with more than two osteotomy sites on the zygomatic complex. As a matter of fact the lateral protrusion of the middle part of the zygomatic arch is the dominant cause of a wide midface or a lateral bulging cheek bone. So to reduce the width of the midface the overly curved zygomatic arch should be straightened, to do so more than two osteotomy sites along the rigid arch are needed. On the other hand, to lessen the arch height of the zygomatic arch, its arc length needs to be shortened because the chord length of the arch has to be kept the same. We introduced a new surgical technique for multiple osteotomy zygomatic arch reduction with a simplified geometric calculations based on the digitalized zygomatic CT image, precisely controlled the amount of bone removal from the zygomatic arch and assured the proper reunion of the arch.
Geometrical Considerations in Zygomatic Arch Reduction Concept The zygomatic arch is a curved bone structure, shaped like an arch bridge. Geometrically, to reduce the height of an arch, the length of the arc must be reduced if the span of the arch remains the same. For patients with a wide face, the middle portion of the arch is augmented laterally too much. To make the face narrower, the degree of the lateral protrusion of the zygomatic arch and the arc length of the zygomatic arch should be reduced. Although the zygomatic arch is an irregular structure, there are still some geometric rules that we can follow in calculating how much arc length should be removed for a certain arch-height reduction.
Evaluation of the Protruding Degree of the Zygomatic Arch A digitalized CT image was used to evaluate the protruding degree of the patient’s zygomatic arch. The following parameters and marks were set up for measuring and calculation. As in Fig. 1, a line drawn from the anterior root (point A) to the posterior root (point B) of the zygomatic arch in the cross-sectional CT image of the zygomatic arch represents the chord of the arch. The most laterally protruding point (MPP) is marked on the arch (point D), and the distance from this point to the chord (from ‘‘D’’ to ‘‘C’’) is the height of the arch (HOA). The anterior root to the most protruding point distance (ARMPPD) and the posterior root to the most protruding point distance (PRMPPD) are from ‘‘A’’ to ‘‘D’’ and ‘‘B’’ to ‘‘D’’.
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Fig. 1 Marks and parameters used for the geometrical evaluation of the zygomatic arch prominence. Line ‘‘A–B’’ represents the chord of the zygomatic arch. Line ‘‘C–D’’ represents the height of the arch (HOA)
To set up the average level of HOA, 1,200 (600 female and 600 male) digitalized CT images of the zygomatic arch were randomly selected from the data bank of two CT centers located in different hospitals. All the candidates were born and lived in the north part of China, aged between 20 and 40 years. The average levels of HOA in this group of study were 6.1 ± 1 mm for females and 5.2 ± 1 mm for males. These average levels of HOA were used as references for patients originated from the north part of China in our practice.
Geometric Equations Regarding Zygomatic Arch Reduction Data of patient’s zygomatic arch CT images with measuring tool software were obtained before surgery. The HOA was measured for each side of the zygomatic arch to evaluate the degree of lateral protrusion. For a patient wanting to lessen his or her HOA to a desired level, the corresponding arc length shortening of the zygomatic arch was calculated as follows. The difference between
and
(Fig. 2) is
the length of the designated shortening of the zygomatic arch (LDSZA). It is a complex procedure to measure or calculate the real arch length of
and
. However, line
segments ‘‘AD’’ and ‘‘BD’’ can be easily measured in a digitalized CT image, and they roughly represent the arch length of ‘‘ and , same as ‘‘A0 D0 ’’ and ‘‘B0 D0 ’’ . So the relationship of ‘‘AD’’ and ‘‘HOA’’ in right-angled DACD applies to the Pythagorean Theorem. The LDSZA
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Fig. 2 Illustrated calculation of the arc length of removal from the zygomatic arch with the Pythagorean theorem. The cross-sectional CT image shows an overly curved zygomatic arch (Left). The
simulation image of the zygomatic arch reduction for the left image indicates the shortening of the arch height and arc length of the zygomatic arch (Right). HOA0 is the desired arch height
can be calculated according to the designative ‘‘HOA’’’ with the following equations: pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi A0 D0 ¼ AD2 HOA2 þ HOA0 2 pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi B0 D0 ¼ BD2 HOA2 þ HOA0 2
indication for a lift, then a coronal incision as described by Baek [15] was selected. To avoid frontal nerve injury, the undermining level at the temporal region was between the superficial and deep temporal fascia as stated by Yang [20] and also over retraction should be avoided when using a retractor to expose the zygomatic arch. When the upper edge of the middle portion of the zygomatic arch was exposed, a small part of the periosteum on the lateral side of the arch was elevated to clear off the soft tissue for ostectomy.
LDSZA AD þ BD A0 D B0 D0
Patients and Methods Patient Information
Reduction of the Zygomatic Arch In the period from 1995 to 2013, a total of 520 patients underwent zygomatic arch reduction using this method. Altogether 1,020 sides of the zygomatic arches have been surgically treated as 20 patients did only unilateral reduction. All the patients were from the north part of China. The age span of the patients was from 18 to 50. The average age was 28 years old and male to female ratio was 125 cases to 395 cases. Ninety-eight patients had previous reduction malarplasty surgery with various techniques such as filing down, anterior or posterior end osteotomy. Indications were HOA [7 mm, healthy, no abnormality of the zygomatic bone and zygomatic arch. Surgical Incisions The intraoral incision was used for every patient to expose the zygomatic bone and the front part of the zygomatic arch. An approximately 3.5-cm-long mucosal incision was made 0.5 cm apart from the upper buccal sulcus between the canine tooth and the second molar tooth. Muscle and soft tissues were blunt dissected until the periosteum of the zygomatic bone was shown. Then the periosteum of the zygomatic bone was incised and elevated to expose the bony surface of the zygomatic bone. The temporal incision was used to expose the rest of the zygomatic arch for most of the patients. If the patient wanted a forehead lift at the same time and there was
After exposure of the zygomatic arch, a compass was used to mark the most protruding point on the lateral surface of the bony arch based on the CT measurement of PRMPPD. This point was set as the center and the length of desired shortening of the zygomatic arch (LDSZA) as the diameter of a bone fragment of the zygomatic arch was marked to be cut off (Fig. 3). A reciprocating saw with a mini blade was employed to cut through the zygomatic arch bone at the marked lines ‘‘C’’ and ‘‘D’’. The bone segment was removed to open the zygomatic arch. Then the lateral cortexes were sawed at the anterior and posterior roots (lines ‘‘A’’ and ‘‘B’’). A gentle inward pushing force was applied on the free ends (‘‘C’’ and ‘‘D’’) of the open arches letting greenstick fracture occur at the roots (‘‘A’’ and ‘‘B’’) and the free ends (‘‘C’’ and ‘‘D’’) meet. The zygomatic arch became a solid and fixed structure again. Mini plates and screws or wires were occasionally used to fix the junction line of the free ends only if the re-bridged zygomatic arch was not stable (Figs. 4, 5).
Result Among the 1,020 sides of zygomatic arch reductions, 880 sides were done through intraoral plus temporal incisions, the other 140 sides through intraoral plus coronal incisions.
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Fig. 3 The ostectomy and osteotomy sites at the zygomatic arch. ‘‘A’’ and ‘‘B’’ mark the greenstick fracture sites at the anterior and posterior roots. ‘‘C’’ and ‘‘D’’ mark the bone resection line
Fig. 4 Multiple osteotomy zygomatic arch reduction with temporal incision. The osteotomy sites are marked as ‘‘A, B, C, and D’’
Fig. 5 After the removal of a bone fragment between ‘‘C’’ and ‘‘D,’’ the zygomatic arch is reduced and reunited
The arch heights of the zygomatic arch were reduced by 3–11 mm, average 5.85 mm. The pre- and post-surgery HOA values are listed in Table 1. Though the HOAs of the right and the left side were different for each patient, there was no statistical significance between the HOAs of the right and the left side in the overall data. The follow-up period ranged from 3 to 30 months, average 12.5 months. All the reduced zygomatic arches were stable constructively, and all patient faces were narrowed as desired without any bouncing back. Post-surgery CT scans were taken in the period of 6–12 months after surgery for 119 sides. All the zygomatic arches in these images looked natural and their arch heights were lessened ideally (Fig. 6). Questionnaires containing 10 questions were used to value the satisfaction rate. These questions included satisfaction with the anterolateral malar prominence reduction, satisfaction with the lateral malar prominence reduction, vision and eye movement disturbance, incision scar, mouth
opening interference, post-surgery discomfort, local numbness, upper lip movement dysfunction, pressure-induced discomfort on surgical sites, and workday loss. Patients were asked to mark each question on a scale from 0 to 10 corresponding from the least favorable to the most favorable. If the overall marks of a questionnaire was 70 or more, then this patient was considered to be satisfied with the surgery. The satisfaction rate for this group of patients was 80 %. The most common complaint was asymmetry of the midface. Almost 10 % of the patients complained of slight asymmetry, even in the after surgery photos their faces looked more symmetric than before surgery. This might due to the patient’s increased sensitivity about their appearances after cosmetic surgery or their expectations of surgery might be too high than what is practical. The common complications for this group of patient are listed in Table 2. Long- and short-term frontalis paralysis was considered to be caused by injuries to the temporal branch of the facial
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Case Reports
His ARMPPDs were 37.2 mm (right) and 41.6 mm (left), PRMPPDs 35.3 mm (right) and 39.9 mm (left). He wanted to reduce his zygomatic arch to the average level (HOA = 5.2 mm). That means his arch height on the right side of the zygomatic arch should be 9.6 mm shorter and left side 9.7 mm shorter. According to the Pythagorean theorem, the lengths of the zygomatic arch needed to be removed were 5.42 mm on the right side and 4.86 mm on the left (Fig. 8). The intraoral and temporal incisions were used. Upon exposure of the zygomatic arch, the most protruding point was marked using the PRMPPD derived from the digital CT calculation of his zygomatic arches, centered with this point 5.4 mm and 4.9-mm-long bone segments were removed with an oscillating saw from the right and left sides of the zygomatic arch, respectively. Greenstick fractures were made on the anterior and posterior root of the zygomatic arch. Then the two open ends of each side of the zygomatic arch were pushed inwardly until both ends met. His post-surgery follow-up lasted for one year after surgery. He is satisfied with the result, and his HOAs remained the same as designed at the one-year follow-up.
Case 1
Case 2
A 22-year-old man complained of a noticeable hump on both sides of his face for 8 years (Fig. 7). A CT scan showed that his HOAs were 14.7 mm (right side) and 14.8 mm (left side).
A 29-year-old woman came complaining of a diamondshaped and asymmetric face (Fig. 9). On physical examination, both sides of her zygomatic arch were protruding and the
Table 1 Pre- and post-surgery CT evaluation of HOA (in mm) for patients in different age groups Age
Female Pre
Male Post
Pre
Post
18–28
11.75 ± 1.81
5.88 ± 0.97
11.01 ± 1.22
5.15 ± 1.55
29–38
11.67 ± 2.02
5.82 ± 1.06
11.06 ± 1.24
5.24 ± 1.48
39–50
12.48 ± 1.97
6.64 ± 1.02
11.04 ± 2.42
5.21 ± 2.35
nerve. It might due to over stretching of the nerve from forced retraction, similar to the other nerve injury-related complications in this group. No infection was observed. Delayed incision healing happened in patients with prolonged (over 3 days) indwelling drainage tubes. Compared to Wang’s [9] overall (early and late) complication rate of 15.7 %, this group is only slightly less. In this group, there were more complications caused by the local nerve disturbance. In Wang’s study, there was more cheek drooping and bone nonunion.
Fig. 6 Cross-sectional CT image at the level of the zygomatic arch shows the changes after multiple osteotomy zygomatic arch reduction malarplasty. Before surgery image (Left).One year after surgery image for the same patient (Right)
Table 2 Complications and their resolving time after surgery
Signs and symptoms
Less than 3 m0
Infraorbital numbness
22
Upper lip dysfunction
3–6 m0
6
10
Frontalis paralysis
10
41
Hematoma
20
Delayed incision healing
12
Total
70
51
More than 6 m0
5
5
Total
Incidence (%)
22
2.2
16
1.6
56
5.5
20
2.0
12
1.2
126
12.4
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Fig. 7 A 22-year-old man had zygomatic arch lateral protrusion on both sides (Left). After multiple osteotomy zygomatic arch reduction, the width of his midface narrowed (Right). The post-surgery photo was taken 1 month after surgery
Fig. 8 Cross-sectional CT image at the level of the zygomatic arch of case 1 shows the arch height, the chord of the zygomatic arch, ARMPPD, and PRMPPD
right side was even more prominent. Her arch height on the right side was 12.6 mm and the left side 15.1 mm (Fig. 10). She wanted her zygomatic arch to be reduced to the average level (HOA = 6.1 mm), so the differences between her HOA and the aimed HOA0 were 6.5 mm (right) and 9.0 mm (left). According to the calculation, segments of 3.96-mm and 6.46-mm zygomatic arch bone were removed from the right and left sides, respectively, using the same procedures as stated above. Her recovery was smooth. A CT scan 2 years after surgery showed that her HOAs on both sides were 6 mm. She is happy with her result.
Discussion Surgical planning and designs are very important in helping surgeons and patients come to an understanding, so to
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improve the satisfaction rate in cosmetic surgeries. Traditionally, cosmetic surgeons evaluate their patients with the naked eye and plan the surgeries in their mind. For maxillofacial surgeries, patient evaluation and surgical planning are even more challenging as the facial bone is invisible under the naked eye. The simplified geometric solution we introduced in this study changed patient evaluation and surgical planning in zygomatic arch reduction surgery. It is common sense that to make the arch height lower for a given arch we must make the chord longer, or the arc length shorter, or both. The zygomatic arch has the same geometric nature. Unfortunately, we cannot extend the distance between the attachments of the anterior and the posterior root of the zygomatic arch. The only choice left is to shorten the arc length. However, how much bone should be removed from each individual zygomatic arch for a certain amount of arch-height reduction is a question that needs to be addressed. If too much of the zygomatic bone is removed, there is a great possibility of disunion [21], no matter how much the arch is pushed inwardly. If the shortening of the arc length is not enough, the facial narrowing effect is compromised. The geometric solutions we used in this study have solved this problem. Protrusions of the zygomatic bone and zygomatic arch have different impacts on the facial contour because of their location. Zygomatic bone protrusion causes a hump below the lateral canthus of the eye, while zygomatic arch protrusion makes the midface wide and bulging out laterally. In our experience, less than 10 % of the patients seeking reduction malarplasty have pure zygomatic bone protrusion. The majority (more than 90 %) have protruding zygomatic arches or combined protrusion of the zygomatic bone and the zygomatic arch. So an effective arch reduction can really
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Fig. 9 A female patient complained of a wide midface and asymmetric cheek bones (Left). The facial contour of this woman changed after surgery and her face looks taller and less bony in the photo (Right). The post-surgery photo was taken 3 years after surgery
Fig. 10 Digitalized CT image of the zygomatic arch shows the different parameters for geometric calculation in case 2
help those who want to narrow their midface. Yang’s method [20] is a good way to reduce the posterior root of the zygomatic arch. The technique described in this paper mainly reduced the most lateral protrusion of the middle portion of the arch with osteotomies on three sites rather than the twosite osteotomies as in Yang’s method. Multiple osteotomies on the zygomatic arch can change the curvature degree of the overly curved zygomatic arch, thus reducing the width of the midface for patients in need. A sagging midface or cheek drooping is a common complication in reduction malarplasty [22, 23]. In our experience, this problem is partially due to the loose tent effect caused by the volume reduction of the underlying zygomatic bone and most importantly by the downward movement of the zygomatic complex itself. Some techniques, such as an L-shaped osteotomy, remove a slice of
the zygomatic bone from the strongest part of the zygomatic complex. When pushed inward the zygomatic complex also moves downwardly along the oblique osteotomy line more or less. And also, delayed drooping may happen because the dynamic stability of the strong part of the zygomatic complex has been compromised by the bone removal. This method of malarplasty only uses greenstick fractures at the strong frontal end of the zygomatic complex, no bone removal from there. The strong part of the arch was well fixed during the surgery and kept strong when the greenstick fracture healed. In this technique, the front part of the zygomatic complex only served as a rotating center, the reduction rate at this point was trivial, so the loose tent effect was avoided. Obviously, this technique was designed mainly for zygomatic arch reduction. The precision control of bone removal from each side of the arch not only allows an accurate arch-height reduction but also can make the midface more symmetric. More than half of the patients’ zygomatic arches were asymmetric enough for special attention in this group. Before the geometric evaluation was used, the control of symmetry of the zygomatic arch relied on the naked eye. It was difficult to compare the size and shape of the arches at both sides during the surgery as full exposure of them at the same time was almost impossible. After the introduction of the geometric calculation, the post-surgery symmetric rate of the midface was greatly improved. However, some factors could affect the accuracy of controlled midfacial width reduction, such as the use of straight lines to represent the irregular curved arch, measuring errors during CT image processing, marking errors and operating errors during the surgery, etc.
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Conclusion Lateral protrusion of an overly curved zygomatic arch is the main cause of a wide midface. Its degree of protrusion can be described numerically with arch height. The amount of bone removed from the arch to achieve a certain archheight reduction effect can be calculated with a simplified geometrical solution. Multiple osteotomies combined with bone removal from the most protruding part of the arch facilitate the reduction of the curvature degree and the arch height of the zygomatic arch. This approach is useful in efficiently narrowing the midface in a precise manner. Acknowledgments We thank Ms Yi Yang for her contribution to this work by her fine drawings. Conflict of interest of interest.
The authors declare that they have no conflict
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8. Nakanishi Y, Nagasao T, Shimizu Y, Miyamoto J, Kishi K, Fukuta K (2012) The boomerang osteotomy—a new method of reduction malarplasty. J Plast Reconstr Aesthet Surg 65: e111–e120 9. Wang T, Gui L, Tang X, Liu J, Yu D, Peng Z, Song B, Song T, Niu F, Yu B (2009) Reduction malarplasty with a new L-shaped osteotomy through an intraoral approach: retrospective study of 418 cases. Plast Reconstr Surg 124:1245–1253 10. Satoh K, Watanabe K (1993) Correction of prominent zygomata by tripod osteotomy of the malar bone. Ann Plast Surg 31:462–466 11. Satoh K, Ohkubo F, Tsukagoshi T (1995) Consideration of operative procedures for zygomatic reduction in Orientals: based on a consecutive series of 28 clinical cases. Plast Reconstr Surg 96:1298–1306 12. Lee JG, Park YW (2003) Intraoral approach for reduction malarplasty: a simple method. Plast Reconstr Surg 111:453–460 13. Lee JS, Kang S, Kim YW (2003) Endoscopically assisted malarplasty: one incision and two dissection planes. Plast Reconstr Surg 111:461–467 discussion 468 14. Sumiya N, Ito Y, Ozumi K (2004) Reduction malarplasty. Plast Reconstr Surg 113:1497–1499 15. Baek SM, Chung YD, Kim SS (1991) Reduction malarplasty. Plast Reconstr Surg 88:53–61 16. Sumiya N, Kondo S, Ito Y, Ozumi K, Otani K, Wako M (1997) Reduction malarplasty. Plast Reconstr Surg 100:461–467 17. Gao ZW, Wang WG, Zeng G, Lu H, Ma HH (2013) A modified reduction malarplasty utilizing 2 oblique osteotomies for prominent zygomatic body and arch. J Craniofac Surg 24:812–817 18. Hwang YJ, Jeon JY (1997) Lee MS a simple method of reduction malarplasty. Plast Reconstr Surg 99:348–355 19. Shao Z, Xie Y, Yu B, Liu L, Du T (2013) A new assisted fixation technique to prevent zygoma displacement in malar reduction. Aesthet Plast Surg 37:692–696 20. Yang DB, Chung JY (2004) Infracture technique for reduction malarplasty with a short preauricular incision. Plast Reconstr Surg 113:1253–1261 discussion 1262–3 21. Lee YH, Lee SW (2009) Zygomatic nonunion after reduction malarplasty. J Craniofac Surg 20:849–852 22. Baek RM, Kim J, Kim BK (2012) Three-dimensional assessment of zygomatic malunion using computed tomography in patients with cheek ptosis caused by reduction malarplasty. J Plast Reconstr Aesthet Surg 65:448–455 23. Baek RM, Kim J, Lee SW (2010) Revision reduction malarplasty with coronal approach. J Plast Reconstr Aesthet Surg 63:2018–2024
ORIGINAL ARTICLE
CRANIOFACIAL/MAXILLOFACIAL
Zygomatic Arch Reduction and Malarplasty with Multiple Osteotomies: Its Geometric Considerations Fushun Ma • Shengjian Tang
Received: 6 March 2014 / Accepted: 28 August 2014 / Published online: 16 October 2014 Ó Springer Science+Business Media New York and International Society of Aesthetic Plastic Surgery 2014
Abstract Background The midfacial width is dominated by the lateral protruding degree of the zygomatic arch. The best way of narrowing the midface is to reduce the arch height and the arc length for patients with an overly curved lateral protruding zygomatic arch. The existing techniques for reduction malarplasty cannot change the degree of curvature of the zygomatic arch. We provide a new technique for efficient midfacial width reduction by multiple osteotomies at different sites on the zygomatic complex and bone resection at the most protruding middle part of the zygomatic arch. The amount of bone resection can be calculated with a simplified geometrical solution according to the desired reduction rate of the arch height. Methods A digitalized CT image was used to estimate the arch height and the length of bone for removal from the zygomatic arch. A specific piece of bone was removed from the most protruding point of each zygomatic arch. Greenstick fractures were made at the anterior and posterior roots of the zygomatic arch. The open arches were rotated inwardly until both ends met. Result The arch heights of 1,020 sides of the zygomatic arch were reduced in a range from 3 to 11 mm. All the reduced zygomatic arches were reunited properly and healed solidly. The overall satisfaction rate was high. Conclusion This technique reduces the width of the midface by changing the degree of curvature of the zygomatic arch. The simplified geometrical calculation solutions are F. Ma S. Tang (&) Plastic Surgery Hospital of Weifang Medical University, 288 Shenglidongjie Kuiwen, Weifang 261042, Shandong, China e-mail: [email protected] F. Ma e-mail: [email protected]
helpful in assuring the reunion of the zygomatic arch at a predesigned lower arc height level after a calculated shortening of the arc length. Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. Keywords Reduction malarplasty Zygoma Geometric evaluation Multiple osteotomies Zygomatic arch Midfacial width
Introduction Reduction malarplasty is a popular surgery among the Oriental population because patients want to make their wide midface narrower in order to achieve a slimmer look. There have been some surgical techniques for reduction malarplasty published such as chiseling and shaving down [1–3], L-shaped or boomerang osteotomy [4–9], tripod osteotomy [10, 11], posterior root osteotomy of the zygomatic arch [12–15], and anterior and posterior root osteotomies with zygomatic arch under tuck techniques [16–19]. The chiseling and shaving technique together with the L-shaped or boomerang technique mainly concentrate on reducing the size of the zygomatic bone or the anterior end of the zygomatic complex. The tripod and anterior or/ and posterior root osteotomy techniques aimed to reduce the zygomatic arch but in a limited degree because if the arch is pushed inward too much, for instance, more than the thickness of the arch, the bone ends will not meet. Above all no previous technique has tried to do the reduction malarplasty by making the overly curved zygomatic arch
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straighter with more than two osteotomy sites on the zygomatic complex. As a matter of fact the lateral protrusion of the middle part of the zygomatic arch is the dominant cause of a wide midface or a lateral bulging cheek bone. So to reduce the width of the midface the overly curved zygomatic arch should be straightened, to do so more than two osteotomy sites along the rigid arch are needed. On the other hand, to lessen the arch height of the zygomatic arch, its arc length needs to be shortened because the chord length of the arch has to be kept the same. We introduced a new surgical technique for multiple osteotomy zygomatic arch reduction with a simplified geometric calculations based on the digitalized zygomatic CT image, precisely controlled the amount of bone removal from the zygomatic arch and assured the proper reunion of the arch.
Geometrical Considerations in Zygomatic Arch Reduction Concept The zygomatic arch is a curved bone structure, shaped like an arch bridge. Geometrically, to reduce the height of an arch, the length of the arc must be reduced if the span of the arch remains the same. For patients with a wide face, the middle portion of the arch is augmented laterally too much. To make the face narrower, the degree of the lateral protrusion of the zygomatic arch and the arc length of the zygomatic arch should be reduced. Although the zygomatic arch is an irregular structure, there are still some geometric rules that we can follow in calculating how much arc length should be removed for a certain arch-height reduction.
Evaluation of the Protruding Degree of the Zygomatic Arch A digitalized CT image was used to evaluate the protruding degree of the patient’s zygomatic arch. The following parameters and marks were set up for measuring and calculation. As in Fig. 1, a line drawn from the anterior root (point A) to the posterior root (point B) of the zygomatic arch in the cross-sectional CT image of the zygomatic arch represents the chord of the arch. The most laterally protruding point (MPP) is marked on the arch (point D), and the distance from this point to the chord (from ‘‘D’’ to ‘‘C’’) is the height of the arch (HOA). The anterior root to the most protruding point distance (ARMPPD) and the posterior root to the most protruding point distance (PRMPPD) are from ‘‘A’’ to ‘‘D’’ and ‘‘B’’ to ‘‘D’’.
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Fig. 1 Marks and parameters used for the geometrical evaluation of the zygomatic arch prominence. Line ‘‘A–B’’ represents the chord of the zygomatic arch. Line ‘‘C–D’’ represents the height of the arch (HOA)
To set up the average level of HOA, 1,200 (600 female and 600 male) digitalized CT images of the zygomatic arch were randomly selected from the data bank of two CT centers located in different hospitals. All the candidates were born and lived in the north part of China, aged between 20 and 40 years. The average levels of HOA in this group of study were 6.1 ± 1 mm for females and 5.2 ± 1 mm for males. These average levels of HOA were used as references for patients originated from the north part of China in our practice.
Geometric Equations Regarding Zygomatic Arch Reduction Data of patient’s zygomatic arch CT images with measuring tool software were obtained before surgery. The HOA was measured for each side of the zygomatic arch to evaluate the degree of lateral protrusion. For a patient wanting to lessen his or her HOA to a desired level, the corresponding arc length shortening of the zygomatic arch was calculated as follows. The difference between
and
(Fig. 2) is
the length of the designated shortening of the zygomatic arch (LDSZA). It is a complex procedure to measure or calculate the real arch length of
and
. However, line
segments ‘‘AD’’ and ‘‘BD’’ can be easily measured in a digitalized CT image, and they roughly represent the arch length of ‘‘ and , same as ‘‘A0 D0 ’’ and ‘‘B0 D0 ’’ . So the relationship of ‘‘AD’’ and ‘‘HOA’’ in right-angled DACD applies to the Pythagorean Theorem. The LDSZA
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Fig. 2 Illustrated calculation of the arc length of removal from the zygomatic arch with the Pythagorean theorem. The cross-sectional CT image shows an overly curved zygomatic arch (Left). The
simulation image of the zygomatic arch reduction for the left image indicates the shortening of the arch height and arc length of the zygomatic arch (Right). HOA0 is the desired arch height
can be calculated according to the designative ‘‘HOA’’’ with the following equations: pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi A0 D0 ¼ AD2 HOA2 þ HOA0 2 pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi B0 D0 ¼ BD2 HOA2 þ HOA0 2
indication for a lift, then a coronal incision as described by Baek [15] was selected. To avoid frontal nerve injury, the undermining level at the temporal region was between the superficial and deep temporal fascia as stated by Yang [20] and also over retraction should be avoided when using a retractor to expose the zygomatic arch. When the upper edge of the middle portion of the zygomatic arch was exposed, a small part of the periosteum on the lateral side of the arch was elevated to clear off the soft tissue for ostectomy.
LDSZA AD þ BD A0 D B0 D0
Patients and Methods Patient Information
Reduction of the Zygomatic Arch In the period from 1995 to 2013, a total of 520 patients underwent zygomatic arch reduction using this method. Altogether 1,020 sides of the zygomatic arches have been surgically treated as 20 patients did only unilateral reduction. All the patients were from the north part of China. The age span of the patients was from 18 to 50. The average age was 28 years old and male to female ratio was 125 cases to 395 cases. Ninety-eight patients had previous reduction malarplasty surgery with various techniques such as filing down, anterior or posterior end osteotomy. Indications were HOA [7 mm, healthy, no abnormality of the zygomatic bone and zygomatic arch. Surgical Incisions The intraoral incision was used for every patient to expose the zygomatic bone and the front part of the zygomatic arch. An approximately 3.5-cm-long mucosal incision was made 0.5 cm apart from the upper buccal sulcus between the canine tooth and the second molar tooth. Muscle and soft tissues were blunt dissected until the periosteum of the zygomatic bone was shown. Then the periosteum of the zygomatic bone was incised and elevated to expose the bony surface of the zygomatic bone. The temporal incision was used to expose the rest of the zygomatic arch for most of the patients. If the patient wanted a forehead lift at the same time and there was
After exposure of the zygomatic arch, a compass was used to mark the most protruding point on the lateral surface of the bony arch based on the CT measurement of PRMPPD. This point was set as the center and the length of desired shortening of the zygomatic arch (LDSZA) as the diameter of a bone fragment of the zygomatic arch was marked to be cut off (Fig. 3). A reciprocating saw with a mini blade was employed to cut through the zygomatic arch bone at the marked lines ‘‘C’’ and ‘‘D’’. The bone segment was removed to open the zygomatic arch. Then the lateral cortexes were sawed at the anterior and posterior roots (lines ‘‘A’’ and ‘‘B’’). A gentle inward pushing force was applied on the free ends (‘‘C’’ and ‘‘D’’) of the open arches letting greenstick fracture occur at the roots (‘‘A’’ and ‘‘B’’) and the free ends (‘‘C’’ and ‘‘D’’) meet. The zygomatic arch became a solid and fixed structure again. Mini plates and screws or wires were occasionally used to fix the junction line of the free ends only if the re-bridged zygomatic arch was not stable (Figs. 4, 5).
Result Among the 1,020 sides of zygomatic arch reductions, 880 sides were done through intraoral plus temporal incisions, the other 140 sides through intraoral plus coronal incisions.
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Fig. 3 The ostectomy and osteotomy sites at the zygomatic arch. ‘‘A’’ and ‘‘B’’ mark the greenstick fracture sites at the anterior and posterior roots. ‘‘C’’ and ‘‘D’’ mark the bone resection line
Fig. 4 Multiple osteotomy zygomatic arch reduction with temporal incision. The osteotomy sites are marked as ‘‘A, B, C, and D’’
Fig. 5 After the removal of a bone fragment between ‘‘C’’ and ‘‘D,’’ the zygomatic arch is reduced and reunited
The arch heights of the zygomatic arch were reduced by 3–11 mm, average 5.85 mm. The pre- and post-surgery HOA values are listed in Table 1. Though the HOAs of the right and the left side were different for each patient, there was no statistical significance between the HOAs of the right and the left side in the overall data. The follow-up period ranged from 3 to 30 months, average 12.5 months. All the reduced zygomatic arches were stable constructively, and all patient faces were narrowed as desired without any bouncing back. Post-surgery CT scans were taken in the period of 6–12 months after surgery for 119 sides. All the zygomatic arches in these images looked natural and their arch heights were lessened ideally (Fig. 6). Questionnaires containing 10 questions were used to value the satisfaction rate. These questions included satisfaction with the anterolateral malar prominence reduction, satisfaction with the lateral malar prominence reduction, vision and eye movement disturbance, incision scar, mouth
opening interference, post-surgery discomfort, local numbness, upper lip movement dysfunction, pressure-induced discomfort on surgical sites, and workday loss. Patients were asked to mark each question on a scale from 0 to 10 corresponding from the least favorable to the most favorable. If the overall marks of a questionnaire was 70 or more, then this patient was considered to be satisfied with the surgery. The satisfaction rate for this group of patients was 80 %. The most common complaint was asymmetry of the midface. Almost 10 % of the patients complained of slight asymmetry, even in the after surgery photos their faces looked more symmetric than before surgery. This might due to the patient’s increased sensitivity about their appearances after cosmetic surgery or their expectations of surgery might be too high than what is practical. The common complications for this group of patient are listed in Table 2. Long- and short-term frontalis paralysis was considered to be caused by injuries to the temporal branch of the facial
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Case Reports
His ARMPPDs were 37.2 mm (right) and 41.6 mm (left), PRMPPDs 35.3 mm (right) and 39.9 mm (left). He wanted to reduce his zygomatic arch to the average level (HOA = 5.2 mm). That means his arch height on the right side of the zygomatic arch should be 9.6 mm shorter and left side 9.7 mm shorter. According to the Pythagorean theorem, the lengths of the zygomatic arch needed to be removed were 5.42 mm on the right side and 4.86 mm on the left (Fig. 8). The intraoral and temporal incisions were used. Upon exposure of the zygomatic arch, the most protruding point was marked using the PRMPPD derived from the digital CT calculation of his zygomatic arches, centered with this point 5.4 mm and 4.9-mm-long bone segments were removed with an oscillating saw from the right and left sides of the zygomatic arch, respectively. Greenstick fractures were made on the anterior and posterior root of the zygomatic arch. Then the two open ends of each side of the zygomatic arch were pushed inwardly until both ends met. His post-surgery follow-up lasted for one year after surgery. He is satisfied with the result, and his HOAs remained the same as designed at the one-year follow-up.
Case 1
Case 2
A 22-year-old man complained of a noticeable hump on both sides of his face for 8 years (Fig. 7). A CT scan showed that his HOAs were 14.7 mm (right side) and 14.8 mm (left side).
A 29-year-old woman came complaining of a diamondshaped and asymmetric face (Fig. 9). On physical examination, both sides of her zygomatic arch were protruding and the
Table 1 Pre- and post-surgery CT evaluation of HOA (in mm) for patients in different age groups Age
Female Pre
Male Post
Pre
Post
18–28
11.75 ± 1.81
5.88 ± 0.97
11.01 ± 1.22
5.15 ± 1.55
29–38
11.67 ± 2.02
5.82 ± 1.06
11.06 ± 1.24
5.24 ± 1.48
39–50
12.48 ± 1.97
6.64 ± 1.02
11.04 ± 2.42
5.21 ± 2.35
nerve. It might due to over stretching of the nerve from forced retraction, similar to the other nerve injury-related complications in this group. No infection was observed. Delayed incision healing happened in patients with prolonged (over 3 days) indwelling drainage tubes. Compared to Wang’s [9] overall (early and late) complication rate of 15.7 %, this group is only slightly less. In this group, there were more complications caused by the local nerve disturbance. In Wang’s study, there was more cheek drooping and bone nonunion.
Fig. 6 Cross-sectional CT image at the level of the zygomatic arch shows the changes after multiple osteotomy zygomatic arch reduction malarplasty. Before surgery image (Left).One year after surgery image for the same patient (Right)
Table 2 Complications and their resolving time after surgery
Signs and symptoms
Less than 3 m0
Infraorbital numbness
22
Upper lip dysfunction
3–6 m0
6
10
Frontalis paralysis
10
41
Hematoma
20
Delayed incision healing
12
Total
70
51
More than 6 m0
5
5
Total
Incidence (%)
22
2.2
16
1.6
56
5.5
20
2.0
12
1.2
126
12.4
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Fig. 7 A 22-year-old man had zygomatic arch lateral protrusion on both sides (Left). After multiple osteotomy zygomatic arch reduction, the width of his midface narrowed (Right). The post-surgery photo was taken 1 month after surgery
Fig. 8 Cross-sectional CT image at the level of the zygomatic arch of case 1 shows the arch height, the chord of the zygomatic arch, ARMPPD, and PRMPPD
right side was even more prominent. Her arch height on the right side was 12.6 mm and the left side 15.1 mm (Fig. 10). She wanted her zygomatic arch to be reduced to the average level (HOA = 6.1 mm), so the differences between her HOA and the aimed HOA0 were 6.5 mm (right) and 9.0 mm (left). According to the calculation, segments of 3.96-mm and 6.46-mm zygomatic arch bone were removed from the right and left sides, respectively, using the same procedures as stated above. Her recovery was smooth. A CT scan 2 years after surgery showed that her HOAs on both sides were 6 mm. She is happy with her result.
Discussion Surgical planning and designs are very important in helping surgeons and patients come to an understanding, so to
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improve the satisfaction rate in cosmetic surgeries. Traditionally, cosmetic surgeons evaluate their patients with the naked eye and plan the surgeries in their mind. For maxillofacial surgeries, patient evaluation and surgical planning are even more challenging as the facial bone is invisible under the naked eye. The simplified geometric solution we introduced in this study changed patient evaluation and surgical planning in zygomatic arch reduction surgery. It is common sense that to make the arch height lower for a given arch we must make the chord longer, or the arc length shorter, or both. The zygomatic arch has the same geometric nature. Unfortunately, we cannot extend the distance between the attachments of the anterior and the posterior root of the zygomatic arch. The only choice left is to shorten the arc length. However, how much bone should be removed from each individual zygomatic arch for a certain amount of arch-height reduction is a question that needs to be addressed. If too much of the zygomatic bone is removed, there is a great possibility of disunion [21], no matter how much the arch is pushed inwardly. If the shortening of the arc length is not enough, the facial narrowing effect is compromised. The geometric solutions we used in this study have solved this problem. Protrusions of the zygomatic bone and zygomatic arch have different impacts on the facial contour because of their location. Zygomatic bone protrusion causes a hump below the lateral canthus of the eye, while zygomatic arch protrusion makes the midface wide and bulging out laterally. In our experience, less than 10 % of the patients seeking reduction malarplasty have pure zygomatic bone protrusion. The majority (more than 90 %) have protruding zygomatic arches or combined protrusion of the zygomatic bone and the zygomatic arch. So an effective arch reduction can really
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Fig. 9 A female patient complained of a wide midface and asymmetric cheek bones (Left). The facial contour of this woman changed after surgery and her face looks taller and less bony in the photo (Right). The post-surgery photo was taken 3 years after surgery
Fig. 10 Digitalized CT image of the zygomatic arch shows the different parameters for geometric calculation in case 2
help those who want to narrow their midface. Yang’s method [20] is a good way to reduce the posterior root of the zygomatic arch. The technique described in this paper mainly reduced the most lateral protrusion of the middle portion of the arch with osteotomies on three sites rather than the twosite osteotomies as in Yang’s method. Multiple osteotomies on the zygomatic arch can change the curvature degree of the overly curved zygomatic arch, thus reducing the width of the midface for patients in need. A sagging midface or cheek drooping is a common complication in reduction malarplasty [22, 23]. In our experience, this problem is partially due to the loose tent effect caused by the volume reduction of the underlying zygomatic bone and most importantly by the downward movement of the zygomatic complex itself. Some techniques, such as an L-shaped osteotomy, remove a slice of
the zygomatic bone from the strongest part of the zygomatic complex. When pushed inward the zygomatic complex also moves downwardly along the oblique osteotomy line more or less. And also, delayed drooping may happen because the dynamic stability of the strong part of the zygomatic complex has been compromised by the bone removal. This method of malarplasty only uses greenstick fractures at the strong frontal end of the zygomatic complex, no bone removal from there. The strong part of the arch was well fixed during the surgery and kept strong when the greenstick fracture healed. In this technique, the front part of the zygomatic complex only served as a rotating center, the reduction rate at this point was trivial, so the loose tent effect was avoided. Obviously, this technique was designed mainly for zygomatic arch reduction. The precision control of bone removal from each side of the arch not only allows an accurate arch-height reduction but also can make the midface more symmetric. More than half of the patients’ zygomatic arches were asymmetric enough for special attention in this group. Before the geometric evaluation was used, the control of symmetry of the zygomatic arch relied on the naked eye. It was difficult to compare the size and shape of the arches at both sides during the surgery as full exposure of them at the same time was almost impossible. After the introduction of the geometric calculation, the post-surgery symmetric rate of the midface was greatly improved. However, some factors could affect the accuracy of controlled midfacial width reduction, such as the use of straight lines to represent the irregular curved arch, measuring errors during CT image processing, marking errors and operating errors during the surgery, etc.
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Conclusion Lateral protrusion of an overly curved zygomatic arch is the main cause of a wide midface. Its degree of protrusion can be described numerically with arch height. The amount of bone removed from the arch to achieve a certain archheight reduction effect can be calculated with a simplified geometrical solution. Multiple osteotomies combined with bone removal from the most protruding part of the arch facilitate the reduction of the curvature degree and the arch height of the zygomatic arch. This approach is useful in efficiently narrowing the midface in a precise manner. Acknowledgments We thank Ms Yi Yang for her contribution to this work by her fine drawings. Conflict of interest of interest.
The authors declare that they have no conflict
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