Pterygoid plate fractures caused by the Le Fort I osteotomy

Le Fort I osteotomies have been carried out on eight cadavers to determine whether pterygomaxillary dysjunction with a curved chisel causes fractures of the pterygoid plates. Fractures occurred on 12 of the 16 sides, were either at the level of the osteotomy cut or near to the base of the skull, and were sometimes multiple. There was no apparent correlation between the presence, type or extent of pterygoid plate fracture and whether or not that side of the osteotomy was completed first.     

Le Fort I osteotomy with sparing fracture of lateral pterygoid plate

This study aimed to clarify the relation between the anatomical variations of the pterygomaxillary region and fracture of the pterygoid plate during Le Fort I osteotomy. We present a secure method to separate maxillary tuberosities from pterygoid plates without injuring the pterygoid plates. Thirty specimens of hemisection of Korean skulls were used for the study. The maxilla was sectioned transversely on the floor of the pyriform aperture and posteriorly to the lateral pterygoid plate with a mechanical saw. The section was 5 to 6 mm above the tooth roots. The pterygomaxillary junction was separated with a curved osteotome in two steps: initially with light tapping of the shallow groove 2 to 3 mm anterior to the pterygomaxillary fissure at a half right angle and then changing the course of forceful tapping to more than 60 degrees. The maxillary tuberosity separated from the medial and lateral pterygoid plates during the procedure was grouped into the "disjunction group" (24 of 30, 80%) and the pterygoid plates fractured were grouped into the "fracture group" (6 of 30, 20%). The thickness of the pterygomaxillary region (T) was significantly greater in the disjunction group than in the fracture group (P = 0.034). The concavity of the pterygomaxillary fissure (C) was significantly deeper in the disjunction group than in the fracture group (P = 0.020). There was no significant difference of width of the pterygomaxillary fissure between the disjunction group and the fracture group (P = 0.169). The thin pterygomaxillary region and less concave pterygomaxillary fissure on the preoperative computed tomography scan draw precautionary attention to vulnerable pterygoid plates fractured in the procedure of Le Fort I osteotomy.     

Use of the 'shark-fin' osteotome in separation of the pterygomaxillary junction in Le Fort I osteotomy: a clinical and computerized tomography study

Le Fort I osteotomy fails in many cases to completely separate the pterygomaxillary junction and often results in fractures of the pterygoid bone and the tuberosity, which subsequently can cause complications. The objectives of this study were to describe the specifically developed Laster 'shark-fin' osteotome and to compare its use to other methods of pterygomaxillary dysjunction. Pterygomaxillary dysjunction was performed in 10 adult patients requiring Le Fort I osteotomy. In one randomly chosen side of the maxilla, the Obwegeser osteotome was used, while the Laster 'shark-fin' osteotome was used on the opposite side. A postoperative computerized tomography of the separation at the pterygomaxillary junctions revealed that in all sites treated with the Laster 'shark-fin' osteotome, a complete or almost complete separation was obtained, whereas the use of the Obwegeser osteotome resulted in five sites with fractures of the maxillary tuberosity and three with high-level fractures of the pterygoid plates (P<0.001). Comparing these findings with the literature, we concluded that the Laster 'shark-fin' osteotome is preferable for separating the pterygomaxillary junction in Le Fort I osteotomy.     

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.

A standard Le Fort I osteotomy was performed on 12 cadavers to determine whether the incidence of pterygoid plate fractures could be reduced by increasing the angle of the curved osteotome relative to the sagittal plane. In the group where an osteotome with the usual angulation was employed, fractures occurred on 9 of 12 sides. In the increased angulation group, 5 of 12 pterygoid plates were fractured. All fractures were restricted to the level of the horizontal osteotomy cut. It is concluded that increased angulation of a curved osteotome can decrease the incidence of fractures of the pterygoid plates. This procedure, however, is not recommended because it can cause fracture of the palatine bone or displacement of the fractured pterygoid plate fragment posteriorly.     

Pattern of pterygomaxillary disarticulation associated with Le Fort I maxillary osteotomy

Pterygomaxillary disarticulation (PMD) contributes to surgical complications of Le Fort 1 osteotomy and is associated with undesirable fractures of the pterygoid plates. The aim of this paper was to investigate the patterns of PMD in Le Fort I osteotomies using Rowe's disimpaction forceps, and to evaluate correlations with age and anatomical measurements. Cone-beam computed tomography (CBCT) scans of 70 consecutive orthognathic patients were retrospectively evaluated to study four patterns of PMD: Type 1 - PMD at, or anterior to, the pterygomaxillary junction (PMJ); Type 2 - PMD posterior to the PMJ; Type 3 - PMJ separation with comminuted fracture of the pterygoid plates; Type 4 - disarticulation of the maxilla involving the pterygoid plates above the level of the osteotomy line. The preoperative anteroposterior and mediolateral thicknesses of the PMJ and the length of the medial and lateral pterygoid plates were assessed. Satisfactory PMD was achieved in all cases and no severe complications were reported, including vascular, dental, mucosal, or neural damage. The most common PMD was Type 1 (54.3%), followed by Type 2 (40%). Comminuted fracture of the pterygoid plates was limited to 5.7% of cases, and no Type 4 was detected. A weak correlation was detected between PMJ thickness and PMD pattern (p = 0.04). No statistically significant correlation was detected between patients’ age and type of PMD. PMD of Le Fort I maxillary osteotomy using a Smith spreader and Rowe's disimpaction forceps proved safe, with minimal damage to the pterygoid plates.     

The evaluation of surgical factors related to recovery period of upper lip hypoaesthesia after Le Fort I osteotomy.

PURPOSE: It is unclear whether surgical factors can affect the upper lip sensitivity. The aim of this study was to assess the factors that can affect the recovery period of hypoaesthesia of the upper lip after Le Fort I osteotomy, using trigeminal somatosensory evoked potential (TSEP) objectively. PATIENTS AND METHODS: Twenty-nine patients with mandibular prognathism underwent Le Fort I osteotomy with and without artificial pterygoid plate fracture. Trigeminal nerve hypoaesthesia at the region of the upper lip was assessed bilaterally by the TSEP method. The distance between the infraorbital foramen and the osteotomy line (IO) or the nearest plate/screw position (IP) was measured on three-dimensional computed tomography (CT). The relationship between the recovery period in upper lip hypoaesthesia and surgical factors (these distances, movement amount, pterygoid plate fracture) were analysed statistically. RESULTS: The recovery period in upper lip hypoaesthesia did not significantly correlate with IO, IP and movement amount. There was no significant difference between pterygoid plate fracture group and non-fracture group. CONCLUSION: Temporary hypoaesthesia of upper lip after Le Fort I osteotomy could not be avoided, however, osteotomy line, plate/screw position and pterygoid plate fracture in Le Fort I osteotomy did not affect the recovery period of upper lip hypoaesthesia with TSEP.     

Transient abducens nerve palsy following a Le Fort I maxillary osteotomy: report of a case

A case of transient abducens nerve palsy following Le Fort I maxillary osteotomy is reported. The results of the CT scan strongly suggest the cause was a fracture of the body of the sphenoid bone but the cause of the fracture is unclear. The palsy occurred on the first postoperative day and recovery took approximately 5 months. The most likely explanation for the complication is a transmittal of force from the osteotome used to fracture through the pterygoid plates extending superiorly through the medial surface of the cavernous sinus. This case clearly demonstrates the importance of care in positioning of the pterygomaxillary osteotome.     

Assessment of lateral pterygoid muscle and temporomandibular joint disc after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy in class II and class III patients

The aim of the study was to examine lateral pterygoid muscle (LPM) and temporomandibular joint (TMJ) disc before and after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy (SSRO) in class II and class III patients.Le Fort I osteotomy and SSRO were performed in class II and class III patients. LPM measurements using oblique sagittal computed tomography (CT) images and TMJ disc position using magnetic resonance imaging (MRI) were examined. Statistical comparisons were performed for the LPM and TMJ between class II and class III patients and between those with and without intentional pterygoid plate fracture in Le Fort I osteotomy.The subjects comprised 60 female patients (120 sides), with 30 diagnosed as class II and 30 as class III. Preoperatively, the width of the condylar attachment, width at eminence, length of the LPM, angle of the LPM, and square of the LPM were significantly smaller in the class II group than in the class III group (p < 0.05). After 1 year, the width of the condylar attachment, width at eminence, and angle of the LPM remained significantly smaller in the class II group than in the class III group (p < 0.0001). TMJ disc position was significantly related to the width of the condylar attachment of the LPM, both pre- and postoperatively (p < 0.0001). However, postoperative disc position did not change in all patients. Next, the class II patients (60 sides) were divided into two groups who underwent Le Fort I osteotomy with or without intentional pterygoid plate fracture. Changes in all measurements of the LPM showed no significant differences between these two groups.Our study suggested that TMJ disc position classification could be associated with the width of condylar attachment of the LPM before and after surgery, while the surgical procedure, including Le Fort I osteotomy with intentional pterygoid plate fracture, might not affect postoperative LMP or disc position in class II patients.     

Evaluation of stress distribution in critical anatomic regions following the Le Fort I osteotomy by three-dimensional finite element analysis

In this study, we aimed to measure the stresses both on the pterygoid plates and the cranial base during the down-fracture and at the time of pterygomaxillary osteotomy by using the finite element analysis method to have an idea about the possible causes of complications. Three different surgical approaches were applied to the obtained models. In the Model 1, Le Fort I cuts without pterygomaxillary separation was applied. In the Model 2, same standard Le Fort I cuts were applied with pterygomaxillary separation. Then both models were subjected to a force of 150 N over the anterior spina nasalis to simulate down-fracture. In the third model, same standard Le Fort I cuts were applied. Following this procedure, a force of 50 N was applied with a sharp osteotome to the pterygomaxillary junction to simulate osteotomy. According to the results of this experimental study, the cranial base stress values decreased during the down-fracture in the Model 2. Moreover, it was found that the force transmitted to the base of the skull is less when the height of the pterygomaxillary osteotome is limited to 1 cm as we applied in Model 3.     

Strain distribution during separation of the pterygomaxillary suture by osteotomes. Comparison between Obwegeser's osteotome and swan's neck osteotome

In the Le Fort I type osteotomy, separation of the pterygomaxillary suture is a dangerous manoeuvre which must be carried out during the surgical procedure. To determine the osteotome best suited for safe separation of the pterygomaxillary suture, we measured the strain distribution over the surrounding bone structures during the osteotomy, employing two types of osteotomes. In both the Obwegeser osteotome group and swan's neck osteotome group, a large strain was measured at the medial pterygoid plate on the side of osteotome application. The intensity of the strain at the medial pterygoid plate was higher in the Obwegeser osteotome group than in the swan's neck group. With the Obwegeser osteotome which is routinely and commonly used in orthognathic surgery, safe separation of the suture cannot be accomplished unless the blade is correctly applied to the suture and superoposterior compression of the pterygoid process is avoided.     

Le Fort I osteotomy using an ultrasonic bone curette to fracture the pterygoid plates

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-2000 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.     

Pterygomaxillary separation in Le Fort I osteotomy UK OMFS consultant questionnaire survey

Pterygomaxillary osteotomy or leverage alone is commonly used to achieve separation of the posterior maxilla from the pterygoid process in the Le Fort I osteotomy. An osteotomy of the tuberosity is less often used. No published data exist on the extent to which surgeons in the UK have adopted these techniques or on the incidence of technique-related vascular complications. We aimed to investigate techniques that are currently used for pterygomaxillary separation and maxillary mobilisation, and the incidence of serious vascular complications among orthognathic surgeons in the UK in 2004. A questionnaire was sent to 301 oral and maxillofacial (OMFS) consultant surgeons in the UK and 205 were returned (response rate 68%). Most of these surgeons (78%) reported that they use an osteotome or a micro-oscillating saw for pterygomaxillary separation. The others use leverage alone or osteotomy of the tuberosity. Eleven (8%) of the surgeons who use a pterygomaxillary osteotome reported that they had had a serious vascular complication in the past year. There were no vascular complications reported by surgeons who use leverage alone or osteotomy of the tuberosity.     

Role of Le Fort type I osteotomy approach in juvenile nasopharyngeal angiofibroma

Le Fort type I osteotomy is a fracture that extends from the pyriform aperture to each of the pterygoid plates, resulting in the detachment of the upper jaw from the cranial base. A retrospective study was conducted on 12 patients with juvenile nasopharyngeal angiofibroma (JNA) who underwent the Le Fort type I approach. Preoperatively, all cases were investigated with computed tomographic scans with contrast and angiography with embolisation. This paper highlights the surgical technique, results and treatment morbidity. The average age of the patients was 21 years, average duration of surgery was 3.2h and average blood loss was 550 ml. All cases had significant symptomatic improvement postoperatively. At 1 year follow up, the authors encountered dental malocclusion in one case and no recurrence of JNA. The Le Fort I osteotomy approach is an excellent approach for the excision of JNA because it allows good surgical exposure, better haemostasis, is cosmetically more acceptable and has a very low morbidity.     

Cranial nerve injury after Le Fort I osteotomy

A Le Fort I osteotomy is widely used to correct dentofacial deformity because it is a safe and reliable surgical method. Although rare, various complications have been reported in relation to pterygomaxillary separation. Cranial nerve damage is one of the serious complications that can occur after Le Fort I osteotomy. In this report, a 19-year-old man with unilateral cleft lip and palate underwent surgery to correct maxillary hypoplasia, asymmetry and mandibular prognathism. After the Le Fort I maxillary osteotomy, the patient showed multiple cranial nerve damage; an impairment of outward movement of the eye (abducens nerve), decreased vision (optic nerve), and paraesthesia of the frontal and upper cheek area (ophthalmic and maxillary nerve). The damage to the cranial nerve was related to an unexpected sphenoid bone fracture and subsequent trauma in the cavernous sinus during the pterygomaxillary osteotomy.     

Biomechanical evaluation of Le Fort I maxillary fracture plating techniques.

PURPOSE: This study used a biomechanical model to examine fundamental questions about rigid plate fixation treatment for maxillary Le Fort I fractures. Specifically, we sought to elucidate the principal strain patterns generated in miniplates and bite force transducers secondary to all masticatory forces, as well as the amount of permanent deformations incurred due to these loading forces. MATERIALS AND METHODS: Forty polyurethane synthetic maxillary and mandibular replicas were used to simulate the mandible and maxilla. Ten replicas were controls (group A). The other 30 were divided into 3 groups (10 each), according to the fixation techniques of 3, 2, and 1 miniplates each side (groups B-D), that were osteotomized in the Le Fort I fracture line on the maxilla. Different forces of masseter medial pterygoid, temporalis, and lateral pterygoid muscles were loaded onto the replicas to simulate different functional conditions (anterior incisor, premolar, and molar clenching). Rosette strain gauges were attached at predefined points on the plates and the bite force transducer to compare the stability and bite force of the different fixation methods for maxillary Le Fort I fractures. RESULTS: Statistically significant differences were found for the deformation of the plates among fixation techniques. The order of stability for each technique was: group B greater than group C greater than group D. In regard to bite force, no difference was found between those found with group A and group B (P > .05), whereas the bite forces of groups C and D were less than those of group A (P < .05). CONCLUSIONS: The fixation of 3 miniplates on each side provides sufficient stability and restores the bite force to the level of the intact maxilla. "The ideal fixation" with 2 miniplates on each side restores 90% of the bite force, and there were more deformations of the miniplates with the "ideal fixation" compared to those found with group B. Group D fixation produced the worst effects for the treatment of maxillary Le Fort I fractures with a weak bite force and insufficient stability.     

Strategies for surgically assisted rapid maxillary expansion according to the region of transverse maxillary deficiency

This study evaluated different techniques for surgically assisted rapid maxillary expansion (SARME) according to the type of transverse maxillary deficiency using computed tomography (CT). Six adult patients with bilateral transverse maxillary deficiencies underwent SARME. The patients were equally divided into three groups: Group I, maxillary atresia in both the anterior and posterior regions; Group II, greater maxillary atresia in the anterior region; and Group III, increased maxillary atresia in the posterior region. In Group I, a subtotal Le Fort I osteotomy was used. In Group II, a subtotal Le Fort I osteotomy was used without pterygomaxillary suture disjunction. In Group III, a subtotal Le Fort I osteotomy was used with pterygomaxillary suture disjunction and fixation of the anterior nasal spine with steel wire. The midpalatal suture opening was evaluated preoperatively and immediately after the activation period using CT. For Group I, the opening occurred parallel to midpalatal suture; for Group II, the opening comprised a V-shape with a vertex on the posterior nasal spine; and for Group III, the opening comprised a V-shape with a vertex at the anterior nasal spine. The conclusion was that the SARME technique should be individualized according to the type of transverse maxillary deficiency.     

Maxillary stability following Le Fort I osteotomy in combination with sagittal split ramus osteotomy and intraoral vertical ramus osteotomy: a comparative study between titanium miniplate and poly-L-lactic acid plate.

PURPOSE: The purpose of this study was to compare changes in maxillary stability after Le Fort I osteotomy with titanium miniplate and poly-L-lactic acid (PLLA) plate (Fixsorb-MX; Takiron Co, Osaka, Japan). PATIENTS AND METHODS: The subjects were composed of 47 Japanese patients with diagnosed jaw deformity: 24 underwent Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO); and 23 underwent Le Fort I osteotomy intraoral vertical ramus osteotomy without internal fixation. Each group was divided into titanium plate and PLLA plate groups. Time course changes between plate groups were compared using lateral and posteroanterior cephalography. RESULTS: Significant differences were identified between titanium plate and PLLA plate groups in A point after Le Fort I osteotomy and SSRO (P < .05). Significant differences existed between titanium plate and PLLA plate groups in vertical component of posterior nasal spine after Le Fort I osteotomy in both combinations with SSRO and intraoral vertical ramus osteotomy (P < .05). However, no significant differences were identified in measurements on posteroanterior cephalography. CONCLUSION: These results suggest a slight tendency for vertical impaction after Le Fort I osteotomy both in combination with SSRO and intraoral vertical ramus osteotomy with PLLA plates, although differences in time course changes were not clinically apparent, and normal occlusion was established in all patients.     

Maxillary distraction resulting in facial advancement at Le Fort III level in cleft lip and palate patients: a report of two cases

An 18-year-old female and a 14-year-old male who had previously received surgery for primary repair of a nonsyndromic cleft lip and palate (including alveolar defect bone grafting) unintentionally developed facial advancement at the Le Fort III level after surgical correction of their maxillary hypoplasia. The Le Fort I osteotomy, originally performed for their maxillary dentoalveolar hypoplasia, was an incomplete osteotomy. It was performed without down-fracture, leaving the pterygomaxillary and septal junctions intact. The gradual advancement of the maxilla during distraction osteogenesis was planned to correct the hypoplastic maxilla, and also prevent subsequent hypernasality; however, during the distraction procedure by means of a rigid external device both patients developed an unintentional facial advancement at the Le Fort III level.     

Orbitofrontal monobloc advancement for Crouzon syndrome

IntroductionUsually, patients suffering from Crouzon syndrome have synostosis of coronal sutures, exophthalmia, hypertelorism, and hypoplasia of the middle third of face. Sometimes maxillary retrusion is absent, so these patients have class I or II relationship. In these cases, frontofacial monobloc advancement, which is the gold standard, increases the maxillo-mandibular dysmorphia. Therefore we propose orbitofrontal monobloc advancement minus dental arch, without splits of the pterygoid plates.Case reportA 12-year-old girl with Crouzon syndrome had intracranial hypertension, exophthalmia, a middle third retrusion and a class II occlusion. We achieved orbitofrontal monobloc advancement which is frontofacial monobloc advancement minus maxillary dental arch. Four distractors KLS Martin were used. After 20 days of distraction, the final advancement was 10.2 mm for cranial distractors and 10.5 mm at fronto-zygomatic. Distractors were removed after 8 months.DiscussionWe offer patients suffering from Crouzon syndrome with class I or II relationship a change from the classic frontofacial monobloc advancement leaving the maxillary dental arch in place, thus avoiding the worsening of the maxillo-mandibular dysmorphia related to surgery. The idea of associating Le Fort I osteotomy with a frontofacial monobloc advancement or Le Fort III osteotomy has already been described, mainly by Tessier and Obwegeser, however they probably achieved a complete Le Fort I osteotomy while we don't split the pterygoid plates.The patient's morphology and his surgical history determine the choice between Le Fort III and monobloc advancement. Dental occlusion needs to be taken into account for surgical indication.     

Le Fort I 型截骨术相关骨性解剖标志的多层CT测量研究

目的:应用多层CT影像测量上颌与LeFortI型截骨手术相关骨性解剖标志,为避免损伤腭降动脉提供指导.方法:选择60例正常成人上颌多层CT扫描图像,应用efilm1.94图像处理软件测量.结果:颧牙槽嵴至翼腭管的距离平均为26mm;翼突的宽度平均为13mm;犁状孔边缘至翼腭管的距离平均为37mm;前后鼻棘的距离为47mm;犁状孔边缘至翼腭管连线与矢状面的角度为7°8'.结论:参照测量获得的解剖数据在术中能降低腭降动脉损伤的发生率.