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Le Fort I osteotomy using an ultrasonic bone curette to fracture the pterygoid plates
ARTICLE IN PRESS Journal of Cranio-Maxillofacial Surgery (2004) 32, 381–386 r 2004 European Association for Cranio-Maxillofacial Surgery doi:10.1016/j.jcms.2004.06.005, available online at http://www.sciencedirect.com
Le Fort I osteotomy using an ultrasonic bone curette to fracture the pterygoid plates Koichiro UEKI, Kiyomasa NAKAGAWA, Kohei MARUKAWA, Etsuhide YAMAMOTO Department of Oral and Maxillofacial Surgery (Chief: Prof. E. Yamamoto, DDS, PhD), Graduate School of Medicine, Kanazawa University, Kanazawa, Japan
SUMMARY. Purpose: The purpose of this study was to evaluate the advantageous use of an ultrasonic bone curette and to assess the mobilization of the pterygoid process after a Le Fort I osteotomy. Material and methods: 14 Japanese adults (ranging in age from 17 to 30 years, mean 22.4) with jaw deformities diagnosed as mandibular prognathism or bimaxillary asymmetry underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy or intraoral vertical ramus osteotomy. During the Le Fort I osteotomy, the Sonopet UST-2000t ultrasonic bone curette was used to fracture the pterygoid process slightly above the level of the maxillary osteotomy without damaging the descending palatine artery or other blood vessels and nerves. After surgery, the pterygoid process osteotomy and its mobility were evaluated from three-dimensional computed tomographic images. Results: In all cases, the mobility of the pterygoid process could be achieved by using the device safely with minimal bleeding and no notable complications. The maxillary segment could be fixed in an ideal position and in all 14 cases, an ideal profile was achieved. Conclusion: Ultrasonic bone curette offers a safe procedure for performing pterygoid process fractures without damaging the surrounding tissue such as the descending palatine artery. r 2004 European Association for Cranio-Maxillofacial Surgery
Keywords: Le fort I osteotomy; Pterygoid process; Ultrasonic bone curette
tion. Therefore, an ultrasonic bone curette was used in performing a Le Fort I osteotomy to mobilize the pterygoid process in order to achieve better results. The purpose of this study was to evaluate the ultrasonic bone curette for mobilizing the pterygoid process after a Le Fort I osteotomy.
INTRODUCTION The Le Fort I osteotomy is currently a popular technique for the correction and treatment of maxillofacial deformities. The standard technique includes separation of the pterygomaxillary junction with a curved osteotome through a blind approach to the pterygomaxillary fissure. This procedure is mainly used in maxillary advancement. In cases that are unsuitable for maxillary advancement, especially those with maxillary asymmetry or maxillary protrusion, the mobility of the pterygoid process is necessary to achieve ideal maxillary movement. An increased knowledge of the basic biology of the Le Fort I osteotomy, the development of instrumentation specially designed for the operation, and the use of hypotensive anaesthesia have dramatically reduced the morbidity and duration of this procedure (Bell et al., 1980; Lanigan, 1990; Epker et al., 1995). Instruments have previously been developed to separate the pterygomaxillary junction clearly (Turvey and Fonseca, 1980; Trimble et al., 1983; Precious et al., 1991, 1993; Cheng and Robinson, 1993; Lanigan and Guest, 1993; Laster et al., 2002). However, after separating the junction, the interference between the pterygoid process and the posterior part of the maxillary segment sometimes prevents ideal maxillary positioning. Managing the pterygoid process has become more important than separating the pterygomaxillary junc-
PATIENTS AND METHODS Patients The 14 Japanese adults in this study presented with jaw deformities diagnosed as mandibular prognathism or bimaxillary asymmetry. At the time of orthognathic surgery, the patients’ age ranged from 17 to 30 years (mean 22.4 years). Surgery Of the 14 patients in this study, 11 underwent a Le Fort I osteotomy and bilateral sagittal split ramus osteotomy or intraoral vertical ramus osteotomy plus osteotomy of the pterygoid process, rigid fixation was achieved with resorbable mini-plates and monocortical screws (Fixorbs-MX, Takiron Co., Osaka, Japan) after maxillary osteotomy and sagittal split osteotomy (Table 1). After several days of rigid maxillo-mandibular fixation, elastic 381
ARTICLE IN PRESS 382 Journal of Cranio-Maxillofacial Surgery
bands were placed to maintain ideal occlusion in patients who underwent sagittal splitting. In patients who underwent vertical ramus ostestomy, the intermaxillary wires were exchanged after 4 weeks for elastic bands to maintain ideal occlusion. All patients received orthodontic treatment before and after surgery. The blood loss was also recorded.
vantage-type computed tomography (CT) generator (GE Medical Systems, Milwaukee, WI, USA), with each sequence taken 2 mm apart in the horizontal plane (parallel to the Frankfurt horizontal plane). Horizontal rotation was defined as a change of the maxilla twisted parallel to the occlusal plane and coronal rotation as a vertical change involving impaction on one side and elongation on the other side (Fig. 1).
Assessment by computed tomography Surgical procedure To assess mobility and displacement of the pterygoid process and the amount of maxillary movement, tomographs were obtained using a high-speed ad-
All patients underwent a standard Le Fort I downfracture osteotomy following a marginal periodontal
Table 1 – Patient data Case number
Diagnosis
Age (years)
Sex
Procedures
1
Mandibular prognathia Bi-maxillary asymmetry Bi-maxillary asymmetry
17
M
Ll,SSRO
6
27
F
L1,IVRO
27
F
2 3
Setback right (mm)
Setback left (mm)
Op time (min)
Bleeding (ml)
Osteotomy of pterygoid process
Maxillary movement
5
200
200
none
4 mm advance
1
2
235
350
bilateral
L1,IVR0
0
0
140
130
bilateral
5 mm horizontal rotation to the left coronal rotation, right 3 mm up and left 3 mm down coronal rotation, right 4 mm up and left 4 mm down coronal rotation, right 3 mm up and left 3 mm down coronal rotation, right 4 mm up and left 4 mm down coronal rotation, right 2 mm up and left 7 mm down coronal rotation, right 3 mm up and left 3 mm down 2 mm advance, 4 mm up at the anterior teeth 4 mm advance
4
Bi-maxillary asymmetry
28
F
L1,IVRO
2
1
230
390
bilateral
5
Bi-maxillary asymmetry, mandibular prognathia Bi-maxillary asymmetry
23
F
L1,IVRO
0
0
270
370
bilateral
21
M
L1,SSRO
1
2
205
200
bilateral
18
F
LI,SSRO
5
3
205
100
bilateral
25
F
Ll,IVRO Genioplasty
0
0
250
270
bilateral
6
7
8
Bi-maxillary asymmetry, mandibular prognathia Bi-maxillary asymmetry
9
Mandibular prognathia
20
F
L1,SSRO
7
12
135
120
none
10
Mandibular prognathia Mandibular prognathia, open bite Bi-maxillary asymmetry
17
F
Ll,SSRO
4
4
135
50
none
16
F
Ll,SSRO
10
5
190
400
bilateral
2 mm advance, whole 4 mm up
27
F
Ll,IVRO
2
2
200
160
bilateral
coronal rotation, right 3 mm up and left 3 mm down coronal rotation, right 3 mm up and left 3 mm down 2 mm advance, 4 mm up at the posterior teeth
11 12
13
Bi-maxillary asymmetry,
18
F
LI,IVRO
1
1
140
50
bilateral
14
Mandibular prognathia, open bite
30
F
L1,SSRO
10
10
235
515
bilateral
197.9 45.1
236.1 147.1
Average SD
22.4 4.8
3.5 3.6
2.8 4.2
SSRO: sagittal split ramus osteotomy, IVRO: intraoral vertical ramus osteotomy, L1: Le Fort I osteotomy.
ARTICLE IN PRESS Le Fort I osteotomy using an ultrasonic bone curette 383
Fig. 1 – (A) Horizontal rotation. Interference between the posterior part of the maxilla and the pterygoid process on one side has to be eliminated to avoid unplanned advancement. (B) Coronal rotation. Reduction of maxillary height of the right side needed for impaction and elongation of the left side at the same time. Mandibular osteotomy also performed to establish ideal occlusion.
incision anteriorly and a vestibular incision near the posterior teeth, Inter-maxillary fixation screws (Stryker LEIBINGER, Freiburg, Germany) were implanted in the anterior alveolar bone of both jaws. The lateral wall of the maxillary sinus was cut using an oscillating saw, the nasal septum and the lateral nasal walls were sectioned with a chisel. The pterygomaxillary separation was performed with an osteotome before the maxilla was down-fractured. A bone separator fixed in a thick bony area of the lateral wall of the maxillary sinus and the screws implanted in the maxilla were used to fracture and pull down the maxilla by means of wires. After this, the posterior wall of the maxillary sinus, the maxillary tuberosity, and the pterygoid process were exposed. When the maxilla was pulled downward and forward and small bone pieces were removed along with surplus sinus membranes, the descending palatine artery could be seen passing from the pterygopalatine fossa to the nasal wall. The Sonopet UST-2000t ultrasonic bone curette (Miwatec Co., Ltd., Kawasaki, Kanagawa, Japan) was used to fracture the pterygoid process slightly above the level of the maxillary osteotomy without damaging the descending palatine artery or other vessels and nerves (Fig. 2). From the posterior aspect of the maxillary sinus, the neurovascular bundle runs through the great palatine canal, located in the posterior sinus wall. Once the maxillary segment was down-fracturel the descending palatine artery and vein could be seen, protected and exposed by a retractor (Fig. 3). Horizontal cutting of the pterygoid process was performed slightly above the level of the maxillary osteotomy. Using the ultrasonic bone curette a horizontal groove was made curving around the anterior portion of the pterygoid process and the
Fig. 2 – Intra-operative findings following down fracture and ultrasonic bone curette in action.
pterygoid process fractured carefully with an osteotome. At this time, the lower part of the pterygoid process was mobilized and any limitation of moving the maxillary segment caused by interference with the pterygoid process was reduced so that the maxillary segment could be moved poster-superiorly (Fig. 3). The maxillary segment was positioned using an intermediate occlusal splint and fixed with absorbable mini-plates and monocortical screws. Ultrasonic bone curette The ultrasonic surgical device consisted of a power supply footswitch, and handpiece. The handpiece weighs 110 g, is 140 mm long and 20 mm in diameter. It is angled at 201 along the handle. Longitudinal vibration amplitude can be varied from 120 to 365 mm at an ultrasonic frequency of 25 kHz.The cooled irrigation fluid (20 1C) emerges near the tip of handpiece, through the sheath; suction equipment is also attached (Hadeishi et al., 2003).
RESULTS In all cases, the descending palatine artery could be visualized intra-operatively. The Le Fort I osteotomy, pterygomaxillary disjunction and pterygoid process osteotomy, was safely achieved with minimal bleeding and no notable complications. Surgical times and blood loss did not differ between the maxillary and mandibular osteotomies, so that they were difficult to analyse statistically. The maxillary segment could be fixed in an ideal position and in all cases, an optimal profile could be achieved (Table 1). In three cases diagnosed as mandibular prognathia there was no interference between the posterior part of the maxillary segment and the pterygoid process
ARTICLE IN PRESS 384 Journal of Cranio-Maxillofacial Surgery
process was obvious in the postoperative CT images (Fig. 4). The eight remaining cases also showed fractures of both the pterygoid processes and slight displacement in three-dimensional CT images. Two more cases diagnosed as mandibular prognathia with open bite underwent impaction of the posterior maxilla after the bilateral pterygoid processes were mobilized. Sufficient impaction posteriorly could be obtained in combination with slight advancement. This maxillary repositioning assisted occlusal and skeletal stability.
DISCUSSION
Fig. 3 – Exposure of the descending palatine artery (large arrows). Small arrows indicate the osteotomy line in the pterygoid process. (A) Prior to moving segment. (B) After moving the segment. (C) Setback of the maxillary segment was possible.
because of a simple advancement of the maxilla. Nine cases diagnosed as bimaxillary asymmetry with or without mandibular prognathia underwent an artificial pterygoid process osteotomy and the mobility of the pterygoid process could be achieved by using the ultrasonic bone curette. In one of these cases, rotation was performed in which the anterior teeth were shifted 5 mm to the left in the horizontal plane without advancement so that the maxillary midline would coincide with the facial midline. In this case, the medioposterior displacement of the left pterygoid
Blood supply to the maxilla following a Le Fort I osteotomy is derived from the palatal vascular pedicle, via the descending palatine artery, as well as the palatine branches of the ascending pharyngeal and facial arteries, and from the buccal vascular pedicle via the posterior superior alveolar artery (Epker, 1984 a,b). Among these, the descending palatine artery is the largest vessel with a mean diameter of 1.7 mm (Li et al., 1996). The descending palatine artery runs from lateral to medial within the fossa and then branches off and descends into the greater palatine canal. It then runs through the canal parallel to the greater palatine nerve and emerges as the greater palatine artery into the oral cavity through the greater palatine foramen. The artery and the nerve create a neurovascular bundle with its concomitant veins. The problem of the pterygomaxillary separation during Le Fort I osteotomies has been investigated in numerous studies aiming at reducing complications. Many reports describe major and minor complications related to the pterygomaxillary junction. These include arteriovenous fistulae, ophthalmological and neurological complications (Precious et al., 1991; Juniper and Stajcic, 1991; Stajcic, 1991; Precious et al., 1993; Cheng and Robinson, 1993; Lanigan and Guest, 1993; Lanigan and Loewy, 1995). The majority of these complications are caused by malpositioning the osteotome or by fractures occurring during separation and extending to the pterygoid plate, the base of skull, or the tuberosity. Pterygoid plate fracture does not directly cause these complications: however, subsequent bleeding and neural damage arising form this may create severe problems. When the maxillary segment is moved and positioned after fracture, interference between the maxilla and the pterygoid process may occur in the pterygomaxillary region. As the palatine artery partly runs in the medial sinus wall, trimming the posterior part of the maxillary segment including the medial wall of the sinus may be difficult. Therefore, fracturing the pterygoid process is occasionally necessary. Maxillary setback is not part of orthognathic planning generally. However, a complete or partial maxillary setback can frequently produce an optimum profile, especially in cases of maxillary protrusion,
ARTICLE IN PRESS Le Fort I osteotomy using an ultrasonic bone curette 385
Fig. 4 – (A) Postoperative 3-D CT image. The osteotomy line and the displacement in the left pterygoid process are shown by arrows. (B) Upper level image. (C) Lower level image in same case. Bilateral pterygoid process fractures were performed and the left pterygoid process was especially displaced medio-posteriorly.
retrognathism, or bimaxillary asymmetry. Furthermore, Japanese patients with prognathism or asymmetry tend to have comparatively less prominent noses than Caucasian patients. For example, in a case of asymmetry with an anteroposteriorly normal maxillary position, maxillary advancement may change the shape of the nose so that it is not aesthetically acceptable. To avoid this, a Le Fort I osteotomy is used to change just the maxillary occlusal plane in the lateral or frontal view without maxillary advancement. However, it was not possible to safely perform an artificial fracture of the pterygoid process without the ultrasonic bone curette. Ultrasonic surgical equipment was developed initially in dentistry for removing dental plaque (Sawamura et al., 1999). In neurosurgery, ultrasonic instruments are used for removing brain tumours. The handpiece of such equipment is small and light with adjustable power
and safe suction systems have become available. An ultrasonic scalpel-type osteotome has recently been developed and used for spinal surgery. This scalpeltype osteotome creates a narrow incision in the vertebral arch for laminectomy and splitting laminoplasty (Hidaka et al., 1998). For preventing damage to the neurovascular bundle in the pterygomaxillary area, this device was very useful.
CONCLUSION Ultrasonic bone curette offers a safe procedure for performing pterygoid process fractures without damaging the surrounding tissues. This technique allows surgeons to perform procedures in the pterygomaxillary area to safely mobilize the pterygoid process.
ARTICLE IN PRESS 386 Journal of Cranio-Maxillofacial Surgery
References Bell WH, Proffit WR, White RP: Surgical Correction of Dentofacial Deformities. Saunders, Philadelphia, 1980 Cheng LH, Robinson PP: Evaluation of a swan’s neck osteotome for pterygomaxillary disjunction in the Le Fort I osteotomy. Br J Oral Maxillofac Surg 31: 52–53, 1993 Epker BN: Vascular considerations in orthognathic surgery. I. Mandibular osteotomies. Oral Surg 57: 467–472, 1984a Epker BN: Vascular considerations in orthognathic surgery. II. Maxillary osteotomies. Oral Surg 57: 473–478, 1984b Epker BN, Stella JO, Fish L: Dentofacial Deformities: Integrated Orthodontic and Surgical CorrectionVol. 1: . Mosby, St Louis, 1995 Hadeishi H, Suzuki A, Yasui N, Satou Y: Anterior clinoidectomy and opening of the internal auditory canal using an ultrasonic bone curette. Neurosurgery 52: 867–871, 2003 Hidaka K, Chiba Y, Takada H: Clinical application of the ultrasonic osteotome for the spinous process-splitting laminoplasty. Spinal Surg 12: 19–24, 1998 Juniper RP, Stajcic Z: Pterygoid plate separation using an oscillating saw in Le Fort I osteotomy. Technical note. J CranioMaxillofac Surg 19: 153–154, 1991 Lanigan DT: Hemorrhage association with orthognathic surgery. Oral Maxillofac Clin North Am 4: 887–889, 1990 Lanigan DT, Guest P: Alternative approaches to pterygomaxillary separation. Int J Oral Maxillofac Surg 22: 131–138, 1993 Lanigan DT, Lowey J: Postoperative computed tomography scan study of the pterygomaxillary separation during the Le Fort I osteotomy using a micro-oscillating saw. J Oral Maxillofac Surg 53: 1161–1166, 1995 Laster Z, Ardekian L, Rachmiel A, Peled M: Use of the shark-fin osteotome in separation of the pterygomaxillary junction in Le Fort I osteotomy: a clinical and computerized tomography study. Int J Oral Maxillofac Surg 31: 100–103, 2002 Li KK, Meara JG, Alexander A: Location of the descending palatine artery in relation to the Le Fort I osteotomy. J Oral Maxillofac Surg 54: 822–825, 1996
Precious DS, Morrison A, Ricard D: Pterygomaxillary separation without the use of an osteotome. J Oral Maxillofac Surg 49: 98–99, 1991 Precious DS, Goodday RH, Bourget L, Skulsky FG: Pterygoid plate fracture in Le Fort I osteotomy with and without pterygoid chisel: a computed tomography scan evaluation of 58 patients. J Oral Maxillofac Surg 51: 151–153, 1993 Sawamura Y, Fukushima T, Terasaka S, Sugai T: Development of a handpiece and probes for a microsurgical ultrasonic aspirator: Instrumentation and application. Neurosurgery 45: 1192–1197, 1999 Stajcic Z: Altering the angulation of a curved osteotome—does it have effects on the type of pterygomaxillary disjunction in Le Fort I osteotomy? An experimental study. Int J Oral Maxillofac Surg 20: 301–303, 1991 Trimble LD, Tideman H, Stoelinga PJ: A modification of the pterygoid plate separation in low-level maxillary osteotomies. J Oral Maxillofac Surg 41: 544–546, 1983 Turvey TA, Fonseca RJ: The anatomy of the internal maxillary artery in the pterygopalatine fossa: its relationship to maxillary surgery. J Oral Surg 38: 92–95, 1980
Dr. Koichiro UEKI, DDS, PhD Department of Oral and Maxillofacial Surgery Graduate School of Medicine Kanazawa University, 13-1 Takaramachi Kanazawa 920-8641 Japan Tel.: +81-76-265-2444 Fax: +81-76-234-4268 E-mail: [email protected] Paper received 12 December 2003 Accepted 24 June 2004
Le Fort I osteotomy using an ultrasonic bone curette to fracture the pterygoid plates Koichiro UEKI, Kiyomasa NAKAGAWA, Kohei MARUKAWA, Etsuhide YAMAMOTO Department of Oral and Maxillofacial Surgery (Chief: Prof. E. Yamamoto, DDS, PhD), Graduate School of Medicine, Kanazawa University, Kanazawa, Japan
SUMMARY. Purpose: The purpose of this study was to evaluate the advantageous use of an ultrasonic bone curette and to assess the mobilization of the pterygoid process after a Le Fort I osteotomy. Material and methods: 14 Japanese adults (ranging in age from 17 to 30 years, mean 22.4) with jaw deformities diagnosed as mandibular prognathism or bimaxillary asymmetry underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy or intraoral vertical ramus osteotomy. During the Le Fort I osteotomy, the Sonopet UST-2000t ultrasonic bone curette was used to fracture the pterygoid process slightly above the level of the maxillary osteotomy without damaging the descending palatine artery or other blood vessels and nerves. After surgery, the pterygoid process osteotomy and its mobility were evaluated from three-dimensional computed tomographic images. Results: In all cases, the mobility of the pterygoid process could be achieved by using the device safely with minimal bleeding and no notable complications. The maxillary segment could be fixed in an ideal position and in all 14 cases, an ideal profile was achieved. Conclusion: Ultrasonic bone curette offers a safe procedure for performing pterygoid process fractures without damaging the surrounding tissue such as the descending palatine artery. r 2004 European Association for Cranio-Maxillofacial Surgery
Keywords: Le fort I osteotomy; Pterygoid process; Ultrasonic bone curette
tion. Therefore, an ultrasonic bone curette was used in performing a Le Fort I osteotomy to mobilize the pterygoid process in order to achieve better results. The purpose of this study was to evaluate the ultrasonic bone curette for mobilizing the pterygoid process after a Le Fort I osteotomy.
INTRODUCTION The Le Fort I osteotomy is currently a popular technique for the correction and treatment of maxillofacial deformities. The standard technique includes separation of the pterygomaxillary junction with a curved osteotome through a blind approach to the pterygomaxillary fissure. This procedure is mainly used in maxillary advancement. In cases that are unsuitable for maxillary advancement, especially those with maxillary asymmetry or maxillary protrusion, the mobility of the pterygoid process is necessary to achieve ideal maxillary movement. An increased knowledge of the basic biology of the Le Fort I osteotomy, the development of instrumentation specially designed for the operation, and the use of hypotensive anaesthesia have dramatically reduced the morbidity and duration of this procedure (Bell et al., 1980; Lanigan, 1990; Epker et al., 1995). Instruments have previously been developed to separate the pterygomaxillary junction clearly (Turvey and Fonseca, 1980; Trimble et al., 1983; Precious et al., 1991, 1993; Cheng and Robinson, 1993; Lanigan and Guest, 1993; Laster et al., 2002). However, after separating the junction, the interference between the pterygoid process and the posterior part of the maxillary segment sometimes prevents ideal maxillary positioning. Managing the pterygoid process has become more important than separating the pterygomaxillary junc-
PATIENTS AND METHODS Patients The 14 Japanese adults in this study presented with jaw deformities diagnosed as mandibular prognathism or bimaxillary asymmetry. At the time of orthognathic surgery, the patients’ age ranged from 17 to 30 years (mean 22.4 years). Surgery Of the 14 patients in this study, 11 underwent a Le Fort I osteotomy and bilateral sagittal split ramus osteotomy or intraoral vertical ramus osteotomy plus osteotomy of the pterygoid process, rigid fixation was achieved with resorbable mini-plates and monocortical screws (Fixorbs-MX, Takiron Co., Osaka, Japan) after maxillary osteotomy and sagittal split osteotomy (Table 1). After several days of rigid maxillo-mandibular fixation, elastic 381
ARTICLE IN PRESS 382 Journal of Cranio-Maxillofacial Surgery
bands were placed to maintain ideal occlusion in patients who underwent sagittal splitting. In patients who underwent vertical ramus ostestomy, the intermaxillary wires were exchanged after 4 weeks for elastic bands to maintain ideal occlusion. All patients received orthodontic treatment before and after surgery. The blood loss was also recorded.
vantage-type computed tomography (CT) generator (GE Medical Systems, Milwaukee, WI, USA), with each sequence taken 2 mm apart in the horizontal plane (parallel to the Frankfurt horizontal plane). Horizontal rotation was defined as a change of the maxilla twisted parallel to the occlusal plane and coronal rotation as a vertical change involving impaction on one side and elongation on the other side (Fig. 1).
Assessment by computed tomography Surgical procedure To assess mobility and displacement of the pterygoid process and the amount of maxillary movement, tomographs were obtained using a high-speed ad-
All patients underwent a standard Le Fort I downfracture osteotomy following a marginal periodontal
Table 1 – Patient data Case number
Diagnosis
Age (years)
Sex
Procedures
1
Mandibular prognathia Bi-maxillary asymmetry Bi-maxillary asymmetry
17
M
Ll,SSRO
6
27
F
L1,IVRO
27
F
2 3
Setback right (mm)
Setback left (mm)
Op time (min)
Bleeding (ml)
Osteotomy of pterygoid process
Maxillary movement
5
200
200
none
4 mm advance
1
2
235
350
bilateral
L1,IVR0
0
0
140
130
bilateral
5 mm horizontal rotation to the left coronal rotation, right 3 mm up and left 3 mm down coronal rotation, right 4 mm up and left 4 mm down coronal rotation, right 3 mm up and left 3 mm down coronal rotation, right 4 mm up and left 4 mm down coronal rotation, right 2 mm up and left 7 mm down coronal rotation, right 3 mm up and left 3 mm down 2 mm advance, 4 mm up at the anterior teeth 4 mm advance
4
Bi-maxillary asymmetry
28
F
L1,IVRO
2
1
230
390
bilateral
5
Bi-maxillary asymmetry, mandibular prognathia Bi-maxillary asymmetry
23
F
L1,IVRO
0
0
270
370
bilateral
21
M
L1,SSRO
1
2
205
200
bilateral
18
F
LI,SSRO
5
3
205
100
bilateral
25
F
Ll,IVRO Genioplasty
0
0
250
270
bilateral
6
7
8
Bi-maxillary asymmetry, mandibular prognathia Bi-maxillary asymmetry
9
Mandibular prognathia
20
F
L1,SSRO
7
12
135
120
none
10
Mandibular prognathia Mandibular prognathia, open bite Bi-maxillary asymmetry
17
F
Ll,SSRO
4
4
135
50
none
16
F
Ll,SSRO
10
5
190
400
bilateral
2 mm advance, whole 4 mm up
27
F
Ll,IVRO
2
2
200
160
bilateral
coronal rotation, right 3 mm up and left 3 mm down coronal rotation, right 3 mm up and left 3 mm down 2 mm advance, 4 mm up at the posterior teeth
11 12
13
Bi-maxillary asymmetry,
18
F
LI,IVRO
1
1
140
50
bilateral
14
Mandibular prognathia, open bite
30
F
L1,SSRO
10
10
235
515
bilateral
197.9 45.1
236.1 147.1
Average SD
22.4 4.8
3.5 3.6
2.8 4.2
SSRO: sagittal split ramus osteotomy, IVRO: intraoral vertical ramus osteotomy, L1: Le Fort I osteotomy.
ARTICLE IN PRESS Le Fort I osteotomy using an ultrasonic bone curette 383
Fig. 1 – (A) Horizontal rotation. Interference between the posterior part of the maxilla and the pterygoid process on one side has to be eliminated to avoid unplanned advancement. (B) Coronal rotation. Reduction of maxillary height of the right side needed for impaction and elongation of the left side at the same time. Mandibular osteotomy also performed to establish ideal occlusion.
incision anteriorly and a vestibular incision near the posterior teeth, Inter-maxillary fixation screws (Stryker LEIBINGER, Freiburg, Germany) were implanted in the anterior alveolar bone of both jaws. The lateral wall of the maxillary sinus was cut using an oscillating saw, the nasal septum and the lateral nasal walls were sectioned with a chisel. The pterygomaxillary separation was performed with an osteotome before the maxilla was down-fractured. A bone separator fixed in a thick bony area of the lateral wall of the maxillary sinus and the screws implanted in the maxilla were used to fracture and pull down the maxilla by means of wires. After this, the posterior wall of the maxillary sinus, the maxillary tuberosity, and the pterygoid process were exposed. When the maxilla was pulled downward and forward and small bone pieces were removed along with surplus sinus membranes, the descending palatine artery could be seen passing from the pterygopalatine fossa to the nasal wall. The Sonopet UST-2000t ultrasonic bone curette (Miwatec Co., Ltd., Kawasaki, Kanagawa, Japan) was used to fracture the pterygoid process slightly above the level of the maxillary osteotomy without damaging the descending palatine artery or other vessels and nerves (Fig. 2). From the posterior aspect of the maxillary sinus, the neurovascular bundle runs through the great palatine canal, located in the posterior sinus wall. Once the maxillary segment was down-fracturel the descending palatine artery and vein could be seen, protected and exposed by a retractor (Fig. 3). Horizontal cutting of the pterygoid process was performed slightly above the level of the maxillary osteotomy. Using the ultrasonic bone curette a horizontal groove was made curving around the anterior portion of the pterygoid process and the
Fig. 2 – Intra-operative findings following down fracture and ultrasonic bone curette in action.
pterygoid process fractured carefully with an osteotome. At this time, the lower part of the pterygoid process was mobilized and any limitation of moving the maxillary segment caused by interference with the pterygoid process was reduced so that the maxillary segment could be moved poster-superiorly (Fig. 3). The maxillary segment was positioned using an intermediate occlusal splint and fixed with absorbable mini-plates and monocortical screws. Ultrasonic bone curette The ultrasonic surgical device consisted of a power supply footswitch, and handpiece. The handpiece weighs 110 g, is 140 mm long and 20 mm in diameter. It is angled at 201 along the handle. Longitudinal vibration amplitude can be varied from 120 to 365 mm at an ultrasonic frequency of 25 kHz.The cooled irrigation fluid (20 1C) emerges near the tip of handpiece, through the sheath; suction equipment is also attached (Hadeishi et al., 2003).
RESULTS In all cases, the descending palatine artery could be visualized intra-operatively. The Le Fort I osteotomy, pterygomaxillary disjunction and pterygoid process osteotomy, was safely achieved with minimal bleeding and no notable complications. Surgical times and blood loss did not differ between the maxillary and mandibular osteotomies, so that they were difficult to analyse statistically. The maxillary segment could be fixed in an ideal position and in all cases, an optimal profile could be achieved (Table 1). In three cases diagnosed as mandibular prognathia there was no interference between the posterior part of the maxillary segment and the pterygoid process
ARTICLE IN PRESS 384 Journal of Cranio-Maxillofacial Surgery
process was obvious in the postoperative CT images (Fig. 4). The eight remaining cases also showed fractures of both the pterygoid processes and slight displacement in three-dimensional CT images. Two more cases diagnosed as mandibular prognathia with open bite underwent impaction of the posterior maxilla after the bilateral pterygoid processes were mobilized. Sufficient impaction posteriorly could be obtained in combination with slight advancement. This maxillary repositioning assisted occlusal and skeletal stability.
DISCUSSION
Fig. 3 – Exposure of the descending palatine artery (large arrows). Small arrows indicate the osteotomy line in the pterygoid process. (A) Prior to moving segment. (B) After moving the segment. (C) Setback of the maxillary segment was possible.
because of a simple advancement of the maxilla. Nine cases diagnosed as bimaxillary asymmetry with or without mandibular prognathia underwent an artificial pterygoid process osteotomy and the mobility of the pterygoid process could be achieved by using the ultrasonic bone curette. In one of these cases, rotation was performed in which the anterior teeth were shifted 5 mm to the left in the horizontal plane without advancement so that the maxillary midline would coincide with the facial midline. In this case, the medioposterior displacement of the left pterygoid
Blood supply to the maxilla following a Le Fort I osteotomy is derived from the palatal vascular pedicle, via the descending palatine artery, as well as the palatine branches of the ascending pharyngeal and facial arteries, and from the buccal vascular pedicle via the posterior superior alveolar artery (Epker, 1984 a,b). Among these, the descending palatine artery is the largest vessel with a mean diameter of 1.7 mm (Li et al., 1996). The descending palatine artery runs from lateral to medial within the fossa and then branches off and descends into the greater palatine canal. It then runs through the canal parallel to the greater palatine nerve and emerges as the greater palatine artery into the oral cavity through the greater palatine foramen. The artery and the nerve create a neurovascular bundle with its concomitant veins. The problem of the pterygomaxillary separation during Le Fort I osteotomies has been investigated in numerous studies aiming at reducing complications. Many reports describe major and minor complications related to the pterygomaxillary junction. These include arteriovenous fistulae, ophthalmological and neurological complications (Precious et al., 1991; Juniper and Stajcic, 1991; Stajcic, 1991; Precious et al., 1993; Cheng and Robinson, 1993; Lanigan and Guest, 1993; Lanigan and Loewy, 1995). The majority of these complications are caused by malpositioning the osteotome or by fractures occurring during separation and extending to the pterygoid plate, the base of skull, or the tuberosity. Pterygoid plate fracture does not directly cause these complications: however, subsequent bleeding and neural damage arising form this may create severe problems. When the maxillary segment is moved and positioned after fracture, interference between the maxilla and the pterygoid process may occur in the pterygomaxillary region. As the palatine artery partly runs in the medial sinus wall, trimming the posterior part of the maxillary segment including the medial wall of the sinus may be difficult. Therefore, fracturing the pterygoid process is occasionally necessary. Maxillary setback is not part of orthognathic planning generally. However, a complete or partial maxillary setback can frequently produce an optimum profile, especially in cases of maxillary protrusion,
ARTICLE IN PRESS Le Fort I osteotomy using an ultrasonic bone curette 385
Fig. 4 – (A) Postoperative 3-D CT image. The osteotomy line and the displacement in the left pterygoid process are shown by arrows. (B) Upper level image. (C) Lower level image in same case. Bilateral pterygoid process fractures were performed and the left pterygoid process was especially displaced medio-posteriorly.
retrognathism, or bimaxillary asymmetry. Furthermore, Japanese patients with prognathism or asymmetry tend to have comparatively less prominent noses than Caucasian patients. For example, in a case of asymmetry with an anteroposteriorly normal maxillary position, maxillary advancement may change the shape of the nose so that it is not aesthetically acceptable. To avoid this, a Le Fort I osteotomy is used to change just the maxillary occlusal plane in the lateral or frontal view without maxillary advancement. However, it was not possible to safely perform an artificial fracture of the pterygoid process without the ultrasonic bone curette. Ultrasonic surgical equipment was developed initially in dentistry for removing dental plaque (Sawamura et al., 1999). In neurosurgery, ultrasonic instruments are used for removing brain tumours. The handpiece of such equipment is small and light with adjustable power
and safe suction systems have become available. An ultrasonic scalpel-type osteotome has recently been developed and used for spinal surgery. This scalpeltype osteotome creates a narrow incision in the vertebral arch for laminectomy and splitting laminoplasty (Hidaka et al., 1998). For preventing damage to the neurovascular bundle in the pterygomaxillary area, this device was very useful.
CONCLUSION Ultrasonic bone curette offers a safe procedure for performing pterygoid process fractures without damaging the surrounding tissues. This technique allows surgeons to perform procedures in the pterygomaxillary area to safely mobilize the pterygoid process.
ARTICLE IN PRESS 386 Journal of Cranio-Maxillofacial Surgery
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Dr. Koichiro UEKI, DDS, PhD Department of Oral and Maxillofacial Surgery Graduate School of Medicine Kanazawa University, 13-1 Takaramachi Kanazawa 920-8641 Japan Tel.: +81-76-265-2444 Fax: +81-76-234-4268 E-mail: [email protected] Paper received 12 December 2003 Accepted 24 June 2004