Pterygoid plate fracture in Le Fort I osteotomy with and without pterygoid chisel: a computed tomography scan evaluation of 58 patients

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.

Transmucosal pterygomaxillary disjunction using a piezoelectric device, in the context of the minimally invasive Le Fort I osteotomy protocol

The aim of this study was to assess the accuracy and clinical implications of pterygomaxillary junction (PMJ) disjunction with a transmucosal PMJ osteotomy using a piezoelectric hand-piece device, in the context of Le Fort I osteotomy, by evaluating the level of PMJ disarticulation and the need for bone trimming around the pedicle. An ambidirectional 1-month follow-up cohort study was designed involving consecutive patients undergoing minimally invasive maxillary Le Fort I osteotomy through the twist technique. Two cohorts were defined according to whether or not the transmucosal PMJ osteotomy was performed. The site of PMJ disjunction was analysed radiographically. A total of 114 patients were included in the study, 57 in each group. The overall accuracy of the PMJ disjunction path was higher in the test group (43.9%) than in the control group (15.8%). Multiple logistic regression analysis identified the need for bone trimming (odds ratio 0.02; P < 0.001) and removal of the upper third molar (odds ratio 0.17; P < 0.001) as relevant factors. In conclusion, compared with the originally described twist technique, combination of the latter with the PMJ osteotomy increased its accuracy at the level of the PMJ. As a result, there is a decrease in resistance during down-fracture and decrease in the need for bone trimming around the pedicle, with preservation of the minimally invasive concept.

Complications According to the Handling of the Pterygoid Plate During Bimaxillary Surgery

BACKGROUND

During bimaxillary surgery, manipulation of the pterygoid plate is required to facilitate movement of the maxilla. This study examined the complications that occurred after handling the pterygoid plate during a Le Fort I osteotomy.

PATIENTS AND METHODS

This study compared and analyzed complications according to the pterygoid plate handling method in 80 patients who underwent bimaxillary surgery at Pusan National University Dental Hospital from December 2015 to July 2020. The pterygoid plate was fractured or removed intentionally only if it interfered with the maxilla. Otherwise, it was not treated. The complications during surgery and the follow-up period were investigated.

RESULTS

Fourteen patients experienced complications, of which excessive bleeding, hearing problems, and nonunion were encountered in 10, 2, and 2 patients, respectively. Of the 10 patients with excessive bleeding patients, the pterygoid plate was manipulated in 8 patients, which was controlled during surgery. Two patients complained of hearing loss with ear congestion immediately after surgery; both patients improved spontaneously within 1 month. Two nonunion patients underwent plate refixation at least 6 months postoperatively, and normal healing was achieved afterward.

CONCLUSIONS

Fracture and removal of the pterygoid plate during orthognathic surgery did not significantly affect the occurrence of complications during and after surgery.

Evaluation of Lefort I Osteotomy Line and Pterygomaxillary Junction Region in Patients With Cleft Lip and Palate

OBJECTIVE

This study aimed to evaluate the Le Fort I osteotomy line and pterygomaxillary junction via cone-beam computed tomography in individuals with cleft lip and palate (CLP).

DESIGN

Retrospective study. Patients and Methods: The study included individuals older than 16 years with CLP, who were scheduled for repositioning of the maxilla by Le Fort I osteotomy, and those with class III malocclusion with maxillary hypoplasia, who were scheduled for Le Fort I osteotomy. The measurements made in the area of the cleft of individuals with CLP were compared with both the side with no cleft and those with class III malocclusion with maxillary hypoplasia. A total of 11 measurements were made on the axial section parallel to the Frankfurt Horizontal plane, corresponding to the lower 1/5 of the distance between the infraorbital foramen and the anterior nasal spine.

RESULTS

There were significant differences both in the comparisons made between the individuals with CLP and those without CLP in terms of the canal-anterior alveolar crest (G) and sinus-anterior alveolar crest (L) measurements (P < .05). The mean measurement values showed that the measurement results were higher in individuals with CLP in general.

CONCLUSION

In conclusion, we believe that there might be difficulties both in osteotomy and down fracture stages during Le Fort I osteotomies performed in individuals with CLP.

Evaluation of the Pterygomaxillary Separation Pattern in Le Fort I Osteotomy Using Different Cutting Instruments

PURPOSE

Pterygomaxillary separation (PMS) is considered the main reason for serious complications associated with Le Fort I osteotomy. The aim of this study was to evaluate whether a piezo surgery, ultrasonic bone scalpel, or conventional bur used in Le Fort I osteotomy has an influence on PMS patterns.

MATERIALS AND METHODS

Using a retrospective cohort study design, we enrolled a sample composed of patients who underwent orthognathic surgery. The primary predictor variables were the cutting instruments (ultrasonic bone scalpel, piezo surgery, and Lindeman bur) used to perform Le Fort I osteotomy. Other variables were demographic and anatomic parameters. The outcome variable was the type of PMS pattern, classified as follows: type 1, PMS at the pterygomaxillary junction (ideal PMS); type 2, PMS at the greater palatine foramen; type 3, PMS from the posterior wall of the maxillary sinus; and type 4, PMS with lateral or medial pterygoid fracture. Anatomic parameters, that is, the thickness and width of the pterygomaxillary junction and distance of the greater palatine foramen, were measured on preoperative cone-beam computed tomography images. The pattern of PMS was evaluated on postoperative cone-beam computed tomography. Data were analyzed using analysis of variance and the Pearson χ² test. P < .05 was considered statistically significant.

RESULTS

This study sample was composed of 96 PMSs in 48 patients. The most common type of PMS was type 1 (58), followed by type 4 (21), type 2 (10), and type 3 (7). A statistically significant relation was found between the cutting instrument and the ideal separation (type 1 PMS) pattern (P = .032), and the highest rate of the ideal separation pattern was seen in the ultrasonic bone scalpel group, at 24 of 32, compared with 22 of 38 in the piezo surgery group and 12 of 26 in the conventional bur group.

CONCLUSIONS

According to the study, the ultrasonic bone scalpel is safer than other cutting instruments in terms of the ideal separation of the pterygomaxillary junction.

Changes of Stress Distributions Around Pterygomaxillary Junction With Different Osteotome Angulations

The aim of this study was to investigate how the alteration of the angulation of osteotome at pterygomaxillary junction affects lateral pterygoid plate, maxillary tuberosity, palatal surface of maxilla, palatine bone and body of sphenoid bone. Following reconstruction of 3D modelling of maxilla, Osteotomes' tip was angulated 45 and 90 to sagittal plane to simulate pterygomaxillary osteotomy. Finite element analyses (FEA) was performed and Von Misses stress distributions were analyzed for two different angulations. Independent sample t test was used to compare differences between 45 and 90 angulations. Von Misses stress values on lateral pterygoid plate were higher in 45 angulation (0.71 ± 0.21 MPa) than 90 angulation (0.54 ± 0.28 MPa). This difference was statistically significant (P < 0.01). Placement of osteotome's tip with 90 angulation had higher stress value than 45 angulation on maxillary tuberosity region. However; difference wasn't significant (P = 0.44). Stress values on body of sphenoid bone were 0.45 ± 0.17MPa for the case of 90 angulation and 0.19 ± 0.09MPa for 45 angulation. Difference between these values were statistically significant (P < 0.01). Possible risk of unfavourable lateral pterygoid plate fracture and complications related with body of sphenoid bone during pterygomaxillary osteotomy was remarkably increased in case of narrow angulation (45). Keeping osteotome at right angle with sagittal plane may avoid these complications.

Evaluation of strain values of critical anatomic regions for two different pterygomaxillary approaches in Le Fort I osteotomy: An experimental study

Background

The purpose of this experimental study was to measure stresses both on the pterygoid plates and the skull base following two different pterygomaxillary approaches in Le Fort I osteotomy.

Material and Methods

The prepared skull models were randomly divided into 2 groups of 7. In the first group (A), the pterygomaxillary area was left intact. In the second group (B), pterygomaxillary separation was performed with a fine bur. The stresses were measured by using strain gauges. These strain gauges were attached to 6 different anatomical sites. The skull models were mounted on a servo-hydraulic testing unit. Each model was then subjected to a continuous linear tension until a plastic deformation was seen.

Results

The statistical analyses showed that there were no significant differences (p >.05) between the 2 groups regarding the strain values. Moreover, no statistical differences (p >.05) were found between the two groups in terms of maximum applied forces.

Conclusions

Considering the clinical conditions, the present study shows that when Le Fort I osteotomy performed without pterygomaxillary separation, there is no significant stress on the skull base during the downfracture. Moreover, it is considered that there is no need for an excessive force applied to perform downfracture in Le Fort osteotomies without pterygomaxillary separation.

Key words:Le Fort I, osteotomy, strain, base of skull, pterygoid process.

Is an osteotome necessary for pterygomaxillary dysjunction or dysjunction through the tuberosity during Le Fort I osteotomy? A systematic review

Pterygomaxillary dysjunction with an osteotome is commonly used to mobilise the maxilla during Le Fort I osteotomy, despite the risk of serious complications. Different instruments and positions have been tried, including dysjunction through the tuberosity. Down fracture by digital pressure alone has also been advocated, but to our knowledge has not been widely adopted. We have therefore reviewed published papers to see if there is any clinical or anatomical evidence for the use of osteotomes to mobilise the maxilla vertically during a Le Fort I osteotomy for either pterygomaxillary dysjunction or dysjunction through the tuberosity. We found only one paper that analysed the anatomy of the pterygomaxillary fissure and described small bony bridges and syncondroses across the joint. We found no clinical or anatomical evidence for the use of osteotomes in pterygomaxillary separation or separation through the tuberosity. A large clinical trial on down fracture of the maxilla by digital pressure alone showed no serious complications, and we found no strong evidence to justify the use of osteotomes in pterygomaxillary dysjunction or dysjunction through the tuberosity. We have successfully used digital pressure alone in 138 consecutive Le Fort I osteotomies, and we encourage our colleagues to consider adopting this approach.

The Comprehensive AOCMF Classification System: Midface Fractures - Level 3 Tutorial

This tutorial outlines the details of the AOCMF image-based classification system for fractures of the midface at the precision level 3. The topography of the different midface regions (central midface-upper central midface, intermediate central midface, lower central midface-incorporating the naso-orbito-ethmoid region; lateral midface-zygoma and zygomatic arch, palate) is subdivided in much greater detail than in level 2 going beyond the Le Fort fracture types and its analogs. The level 3 midface classification system is presented along with guidelines to precisely delineate the fracture patterns in these specific subregions. It is easy to plot common fracture entities, such as nasal and naso-orbito-ethmoid, and their variants due to the refined structural layout of the subregions. As a key attribute, this focused approach permits to document the occurrence of fragmentation (i.e., single vs. multiple fracture lines), displacement, and bone loss. Moreover, the preinjury dental state and the degree of alveolar atrophy in edentulous maxillary regions can be recorded. On the basis of these individual features, tooth injuries, periodontal trauma, and fracture involvement of the alveolar process can be assessed. Coding rules are given to set up a distinctive formula for typical midface fractures and their combinations. The instructions and illustrations are elucidated by a series of radiographic imaging examples. A critical appraisal of the design of this level 3 midface classification is made.

Preoperative and Postoperative CT Scan Assessment of Pterygomaxillary Junction in Patients Undergoing Le Fort I Osteotomy: Comparison of Pterygomaxillary Dysjunction Technique and Trimble Technique-A Pilot Study

PURPOSE

To determine the rate of complications and occurrence of pterygoid plate fractures comparing two techniques of Le Fort I osteotomy i.e., Classic Pterygomaxillary Dysjunction technique and Trimble technique and to know whether the dimensions of pterygomaxillary junction [determined preoperatively by computed tomography (CT) scan] have any influence on pterygomaxillary separation achieved during surgery.

MATERIALS AND METHODS

The study group consisted of eight South Indian patients with maxillary excess. A total of 16 sides were examined by CT. Preoperative CT was analyzed for all the patients. The thickness and width of the pterygomaxillary junction and the distance of the greater palatine canal from the pterygomaxillary junction was noted. Pterygomaxillary dysjunction was achieved by two techniques, the classic pterygomaxillary dysjunction technique (Group I) and Trimble technique (Group II). Patients were selected randomly and equally for both the techniques. Dysjunction was analyzed by postoperative CT.

RESULTS

The average thickness of the pterygomaxillary junction on 16 sides was 4.5 ± 1.2 mm. Untoward pterygoid plate fractures occurred in Group I in 3 sides out of 8. In Trimble technique (Group II), no pterygoid plate fractures were noted. The average width of the pterygomaxillary junction was 7.8 ± 1.5 mm, distance of the greater palatine canal from pterygomaxillary junction was 7.4 ± 1.6 mm and the length of fusion of pterygomaxillary junction was 8.0 ± 1.9 mm.

DISCUSSION

The Le Fort I osteotomy has become a standard procedure for correcting various dentofacial deformities. In an attempt to make Le Fort I osteotomy safer and avoid the problems associated with sectioning with an osteotome between the maxillary tuberosity and the pterygoid plates, Trimble suggested sectioning across the posterior aspect of the maxillary tuberosity itself. In our study, comparison between the classic pterygomaxillary dysjunction technique and the Trimble technique was made by using postoperative CT scan. It was found that unfavorable pterygoid plate fractures occurred only in dysjunction group and not in Trimble technique group. Preoperative CT scan assessment was done for all the patients to determine the dimension of the pterygomaxillary region. Preoperative CT scan proved to be helpful in not only determining the dimensions of the pterygomaxillary region but we also found out that thickness of the pterygomaxillary junction was an important parameter which may influence the separation at the pterygomaxillary region.

CONCLUSION

No untoward fractures of the pterygoid plates were seen in Trimble technique (Group II) which makes it a safer technique than classic dysjunction technique. It was noted that pterygoid plate fractures occurred in patients in whom the thickness of the pterygomaxillary junction was <3.6 mm (preoperatively). Therefore, preoperative evaluation is important, on the basis of which we can decide upon the technique to be selected for safer and acceptable separation of pterygomaxillary region.

Classification and characteristics of pterygoid process fracture associated with maxillary transverse fracture

OBJECTIVE

This study aimed to classify pterygoid process fractures associated with maxillary transverse fractures.

STUDY DESIGN

Pterygoid process fractures in 100 patients with maxillary transverse fractures were observed 2- and 3-dimensionally using image processing software. Fracture line course and height and sphenoid sinus involvement were recorded.

RESULTS

Pterygoid process fractures were classified as follows: class I, vertical (simple separation between medial and lateral plates); or class II, transverse (3 subcategories according to location of fracture line: II-1, within pterygoid fossa; II-2, above pterygoid fossa, not extending to sphenoid sinus floor; II-3, above pterygoid fossa, involving sphenoid sinus floor). Class I fracture was observed on 5 sides (2.7%); II-1, on 125 (66.5%); II-2, on 36 (19.1%); and II-3, on 22 (1.7%).

CONCLUSIONS

Pterygoid process fractures were predominantly near the upper edge of the pterygoid fossa. Pneumatization of the pterygoid process is a risk in fractures involving the sphenoid sinus floor.

Delayed progressive haematoma after Le Fort I osteotomy: A possible severe complication in orthognatic surgery

Although the Le Fort I osteotomy is a safe surgical technique, many complications have been reported. We present a case of an extended cervico-facial haematoma due to delayed bleeding from the terminal branches of the maxillary artery after orthognatic surgery. A 23-year-old man was referred to our observation for the surgical correction of a class III asymmetric malocclusion. The patient underwent a Le Fort I osteotomy, with impaction of the maxilla, associated with an Epker mandibular bilateral sagittal split osteotomy, with maxillary advancement and rigid internal fixation of the mandible with four miniplates and another four for the upper maxilla as well. The first post-surgery day, the patient developed a gradual dispnea together with neck swelling. By second postoperative day, the patient's general condition improved with a progressive normalization of laboratory tests values. The Computerised Axial Tomography (CAT) scan confirmed a decrease in the parapharyngeal thickening. Total recovery was achieved within two months, the final clinical check showed a healthy appearance with good occlusion. An increased knowledge of the basic biology of the Le Fort I osteotomy, the development of instruments specially designed for the Le Fort I procedure and the use of hypotensive anaesthesia could reduce the morbidity and duration of this procedure.

Orthodontic-surgical treatment: neuromuscular evaluation in skeletal Class II and Class III patients

OBJECTIVES

The aim of this study was the evaluation of the neuromuscular response to treatment according to diagnostic phases, as a follow-up of patients under surgical orthodontic treatment. The patient sample was subdivided into sub-samples, according to clinical characteristics.

MATERIALS AND METHODS

All of the patients who underwent orthognathic surgery in the Department of Orthodontics (University of Milan) were subjected to periodic electromyographic evaluation of the masticatory muscles (masseter and anterior temporal muscles), and to electrokinesiographic evaluation of the mandibular movements. The patient sample comprised 80 patients (37 males; and 43 females) at the end of growth. The electromyographic instruments used in the study included a Freely and a K6-I electromyography. Statistical evaluation was carried out with the Student's t-tests for independent samples.

RESULTS

There are many differences between the skeletal Class II and skeletal Class III patients that are shown through the analysis of these data obtained. In the beginning phases of the treatment the muscular activities were higher in the Class II patients than in the Class III patients. Nevertheless this difference was reversed at the end of the treatment. A similar difference could be found in the mandibular kinesiology, in fact the maximum mandibular opening movement was greater in the skeletal Class II patients than in the skeletal Class III patients at the beginning of the treatment. At the end of the treatment this difference was lost. At the beginning of the treatment the Class II patients showed a greater protrusive movement of the mandibular than the Class III patients. At the end the treatment however this gap was reduced without being reversed.

CONCLUSIONS

Functional evaluation in patients in surgical orthodontic therapy is an important element in the diagnostic-therapeutic recordings, so as to reduce as much as possible any incorrect neuromuscular activity that can result in relapse.

Factors predictive of pterygoid process fractures after pterygomaxillary separation without using an osteotome in Le Fort I osteotomy

OBJECTIVE

This study demonstrated pterygomaxillary disjunction patterns and elucidated factors related to unfavorable pterygomaxillary junction fractures in Le Fort I osteotomy without using an osteotome.

STUDY DESIGN

Clinical and anatomical data obtained from computed tomography images (100 sides) were analyzed for their ability to predict patterns of pterygomaxillary disjunction.

RESULTS

Separation of the pterygomaxillary junction was most frequently performed at the maxillary tuberosity (48.0%). Twenty-eight pterygoid plates were fractured. Male gender, increased age, thickness of the pterygomaxillary junction, and length of the maxillary tuberosity were significant risk factors for pterygoid process fractures. We also identified that a pterygomaxillary junction thickness less than 2.6 mm and a maxillary tuberosity length of more than 11.5 mm indicated a statistically significant risk of pterygoid process fractures.

CONCLUSIONS

Prediction of frangible pterygoid plates by preoperative quantitative evaluation of morphometric values provides useful information for selecting safe procedures.

Photoelastic analysis of stress distribution of surgically assisted rapid maxillary expansion with and without separation of the pterygomaxillary suture

PURPOSE

The aim of this study was to evaluate in vitro the mechanical effect over teeth and bone structures of surgically assisted rapid maxillary expansion (SARME) in photoelastic analogs by observing stress produced during Hyrax-type and Haas-type appliances activation.

MATERIALS AND METHODS

Two photoelastic analogs were fabricated by use of birefringent materials to simulate an adult skull that contained teeth, bone, and maxillary sinus. Hyrax-type and Haas-type appliances were applied to the anchor teeth and incrementally activated. SARME was simulated by subsequent cuts of the lateral maxillary wall and midpalatine suture and separation of the pterygomaxillary junction. After each osteotomy, the appliances were activated. Resulting stress patterns were recorded photographically in the field of a plane polariscope.

RESULTS

Before any osteotomy, the activation of the appliances distributed stress through the anchoring teeth to the zygomaticomaxillary walls, concentrating at the zygomaticomaxillary and zygomaticofrontal sutures and at the midline of the maxilla. After midpalatal and maxillary wall osteotomies, a marked reduction of the stress at the zygomaticomaxillary walls was observed. With successive activations, the stresses increased in intensity at the molars, maxillary tuberosity, and pterygoid plates. After pterygomaxillary separation, the stress intensity at the molar area, maxillary tuberosity, and pterygoid plates decreased considerably. With successive activations, stress increased in intensity around the molars and maxillary tuberosity. There were no differences between stresses produced by the 2 appliances.

CONCLUSIONS

In this biomechanical model, sectioning of all maxillary articulations, including separation of the pterygomaxillary junction, caused a decrease in stress over anchorage teeth. These data cannot be completely extrapolated to the clinical situation but indicate that electing to perform the SARME technique should be based on periodontal health and amount of expansion necessary for each case.

Assessment of pterygomaxillary separation in Le Fort I Osteotomy in class III patients

PURPOSE

To examine the separation of the pterygomaxillary region at the posterior nasal spine level after Le Fort I osteotomy in Class III patients.

PATIENTS AND METHODS

The study group consisted of 37 Japanese patients with mandibular prognathism and asymmetry, with maxillary retrognathism or asymmetry. A total of 74 sides were examined. Le Fort I osteotomy was performed without a pterygoid osteotome, with an ultrasonic curette used to remove interference at the pterygomaxillary region. Postoperative computed tomography (CT) was analyzed for all patients. The separation of the pterygomaxillary region and the location of the descending palatine artery were assessed.

RESULTS

Although acceptable separation between the maxilla and pterygoid plates was achieved in all patients, an exact separation of the pterygomaxillary junction at the posterior nasal spine level was found in only 18 of 74 sides (24%). In 29 of 74 sides (39.2%), the separation occurred anterior to the descending palatine artery. In 29 of 74 sides (39.2%), complete separation between the maxilla and lateral and/or medial pterygoid plate was not achieved, but lower level separation of the maxilla and pterygoid plate was always complete. The maxillary segments could be moved to the postoperative ideal position in all cases.

CONCLUSION

Le Fort I osteotomy without an osteotome does not always induce an exact separation at the pterygomaxillary junction at the posterior nasal spine level, but the ultrasonic bone curette can remove the interference between maxillary segment and pterygoid plates more safely.

Complications of Orthognathic Surgery

Complications in orthognathic surgery may stem from occurrences at anyone of many time points during the course of the patient's treatment: preoperative judgment and planning, perioperative orthodontic care, or intraoperatively. This article specifically addresses those complications that arise as a result of intraoperative technique. Such complications may broadly be characterized as airway, vascular, neurologic, infectious, skeletal, or aesthetic in nature. For each type, specific complications, their prevention, and their treatment are discussed.

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.

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.

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.

Perioperative complications in corrective facial orthopedic surgery: a 5-year retrospective study

PURPOSE

Frequency and severity of complications have a profound impact on referral patterns for facial orthopedic surgery. Therefore, a retrospective study was undertaken to determine the incidence of such problems in a large series of patients, with the intent to use these data to make possible changes in the perioperative protocol used in our clinic.

PATIENTS AND METHODS

The files of all patients operated on between 1992 and 1996 were studied. These comprised 1,108 patients with 1,872 osteotomy procedures. The following parameters were descriptively analyzed: airway obstruction, hemorrhage, hematoma, infection, neurosensory disturbances, unfavorable fractures, malposition of condyles and nasal septum, and vascularization problems.

RESULTS

The most frequent complication was impairment of trigeminal nerve function. In 31.5% of the mandibular base osteotomies, 43.6% of the combined mandibular base and chin osteotomies, and 13% of the chin osteotomies, lip sensibility was decreased immediately postoperatively. After 1 year, this number was reduced to approximately 5%. The function of 17 lingual nerves and 45 infraorbital nerves was temporarily impaired. A wound infection was next in frequency. Fifty-three infections (mandible-to-maxilla ratio, 2.5:1) were treated with drainage under local anesthesia and antibiotic therapy. Loss of part or all of an osteotomized segment did not occur. Other complications were rare and/or temporary.

CONCLUSIONS

The most frequent complication was impairment of inferior alveolar nerve function. Life-threatening complications were not encountered. The frequency of infections (<5%) requires further consideration regarding ways to reduce the incidence.

Blindness as a complication of Le Fort osteotomies: role of atypical fracture patterns and distortion of the optic canal

Blindness in patients suffering maxillofacial trauma is usually caused by optic nerve or optic canal injuries. It is, however, an uncommon complication of facial trauma, with a reported incidence of only 3 to 5 percent. This incidence drops dramatically when fractures are performed in the controlled situation of orthognathic surgery. Given the rarity of ophthalmic complications after traumatic Le Fort I injuries, it is not surprising that few cases have been reported after orthognathic surgery. In this article, three cases of visual loss or skull base injury after elective Le Fort I osteotomy are described. All of these cases were presumably straightforward surgically and were performed by experienced surgeons. The literature is reviewed and the pathomechanics of each injury are experimentally explored in a cadaver model. To determine the presence of increased pressure on the optic nerve, optic canal deformation, or fractures extending to the skull base, two separate experiments were devised. In the first experiment, a pressure transduction system was used to document any significant forces that may be directly transmitted to the contents of the optic canal during pterygomaxillary separation. Then tested was the hypothesis that a stepped or tapered osteotomy will allow for a more predictable pterygomaxillary fracture. One of five cadaver specimens in group 1 demonstrated a transient increase in the right optic canal pressure during down-fracture of the maxilla. This change was less than 10 mmHg, and its duration was less than 5 seconds. The canal pressure returned to baseline with the completion of the fracture. In group 2, there was no documented pressure change with either osteotomy technique. Of note, in group 2, all specimens undergoing standard Le Fort osteotomy demonstrated uncontrolled propagation of the fracture lines superiorly in the pterygoid bones. The uncontrolled and unpredictable nature of pterygomaxillary disjunction may result in the extension of fractures to the skull base or the generation of deforming forces to the optic canal may compress or injure the optic nerve and its circulation. It is proposed that a stepped or tapered osteotomy will generate a more controlled pterygomaxillary separation during orthognathic surgery and may reduce the risk of devastating ophthalmologic complications.

Posterior maxillary anatomy: implications for Le Fort I osteotomy

The most common site of haemorrhage in maxillary osteotomies is the posterior maxilla. Better understanding of the anatomy in this region may minimize possible vascular complications. The aim of the study was to study the osteology of the posterior maxillary region and establish clinical safety guidelines for the Le Fort I osteotomy Thirty human dry skulls were selected and assessed by a combination of direct inspection, computerized imaging and computed tomography (CT) scan analysis. Results showed that the presence of maxillary third molars influenced the transverse angulation of the posterior vertical cut. Synostosis of the pterygomaxillary junction was noted in 12% of samples. The mean length of the medial sinus wall from the piriform rim to the descending palatine canal at the Le Fort I level was 34 mm. The three-dimensional CT-reconstructed descending palatine canal ran at 60 degrees anteroinferiorly to the palatine plane and slightly medially to the exit through the greater palatine foramen.

Perioperative morbidity in maxillofacial orthopaedic surgery: a retrospective study

The data of 2049 patients, who underwent maxillofacial orthopaedic surgery, were retrospectively analysed for major intra- and immediate postoperative complications. Immediate life-threatening complications were very rare. They can in most cases be avoided by good anaesthetic and surgical techniques and adequate postoperative care. The most frequently encountered problem in maxillary surgery is excessive blood loss, whilst a compromised airway due to swelling is the most frequent complication in mandibular surgery. Good co-operation between anaesthetist and surgeon is essential to prevent major intraoperative and immediate postoperative problems.

Postoperative computed tomography scan study of the pterygomaxillary separation during the Le Fort I osteotomy using a micro-oscillating saw

PURPOSE

The objective of the study was to evaluate the type of pterygomaxillary separation that occurs with use of a micro-oscillating saw.

PATIENTS AND METHODS

Sixteen patients underwent a postoperative computed tomography scan.

RESULTS

Ideal or near-ideal separations occurred on 26 of 32 sides (81%), while low-level fractures occurred in 6 of 32 sides (19%). No high-level fractures of the pterygoid plates, or fractures extending to the base of the skull or orbit, were seen. There was a striking difference in the number of ideal separations on the right-hand side (94%), compared with the left-hand side (50%), probably because of the greater difficulty of a right-handed surgeon positioning the saw blade correctly on the left side without bending the thin flexible saw blade backward.

CONCLUSION

In view of the high percentage of ideal pterygomaxillary separations achieved using a micro-oscillating saw, and the absence of high-level pterygoid plate fractures extending to the base of the skull, this technique is recommended for the pterygomaxillary dysjunction.

Traumatic aneurysm of the maxillary artery: the role of interventional radiology. A report of two cases

Two cases of post-traumatic aneurysm of the maxillary artery are described. The first patient was a 20-year-old man who sustained a Le Fort III type fracture in a road traffic accident. He experienced two episodes of significant maxillofacial haemorrhage, the first following admission and the second 5 days after initial reduction and fixation of his midfacial fractures. The second patient was a 23-year-old man with a bilateral cleft palate and extreme midfacial hypoplasia who underwent Le Fort I osteotomy. Significant bleeding commenced 3 h postoperatively and was not completely controlled by anterior and posterior nasal packing. Both the aneurysms were diagnosed on selective carotid angiography and successfully treated by embolization.