Relevant Surgical Anatomy of Pterygomaxillary Dysjunction in Le Fort III Osteotomy

Reducing the risk of unfavourable fractures in Le Fort III osteotomy via a navigation-guided technique

The aim of this study was to investigate the clinical feasibility of reducing the risk of unfavourable fractures during Le Fort III osteotomy by using a navigation-guided technique. A study was carried out involving 20 patients with Crouzon syndrome treated with Le Fort III osteotomy and distraction osteogenesis from 2018 to 2023 at the International Hospital of Peking University. The Le Fort III osteotomy procedure in experimental group (9 patients) was carried out under the guidance of navigation technique, while in historical control group (11 patients) was carried out by free hand. Immediate postoperative CT scans were acquired within 24h after surgery to observe the osteotomy lines and detect unfavourable fracture lines. There were 4 patients with unfavourable fractures in the navigation group (4/9 = 44%) while 10 patients in the freehand group (10/11 = 91%), with a statistically significant difference in the probability of unfavourable fracture and the number of fracture lines between the two groups (P < 0.05). The difference in unfavourable fracture incidence in the two groups was significant in zygomatic area (P < 0.05) while not significant in mid-palatal area (P > 0.05). And the surgical duration of the navigation group was significantly shorter than that of the freehand group (216 min vs 280 min) (P < 0.05). The above findings suggest that the navigation-guided technique is effective in reducing the risk of unfavourable fractures in Le Fort III osteotomy procedure and decreasing the surgical duration.

Modified Anterior Z Le Fort III Osteotomy

Introduction

Surgery of the midface for non-syndromic patients with maxillo-malar hypoplasia exclusively has had many breakthroughs lately. The surgical techniques for midface surgery are varied and must be selected according to the patient's problem.

Purpose

The technique is a modification of the Z Osteotomy, the Modified Anterior Z Le Fort III Osteotomy (MAZLFIIIO), is used to correct posteroanterior midface deficiency of 6 mm at most. It can be combined simultaneously with a Le Fort I osteotomy if a greater maxillary advance is needed. MAZLFIIIO advances midface without grafts or distraction osteogenesis. The anterior reposition of the midface is calculated in millimetres and depends on the relation of the eye's most inferior point, as well as the orbital's hard and soft tissues. It is a predictable osteotomy, only for patients without vertical excess of the midface. The osteotomy planned is drawn over a stereolithographic model, and then Z-shaped surgical splints are fabricated over it. Transverse midface deficiencies of no more than 4 mm can also be corrected during the malar osteotomy. A great number of patients are operated exclusively with Le Fort I osteotomies, leaving behind an undesirable step between the upper part of the midface and the Le Fort I osteotomy.

Methods

The Modified anterior Z Le Fort III Osteotomy (MAZLFIIIO) was performed in seven patients, from 2016 to 2018.

Results

The results obtained with the proposed osteotomy notably improve the appearance of the patient and provide a better protection of the lower part of the eye, while widening the maxillary sinus.

Conclusion

We consider that maxillo-malar hypoplasias are very common; the surgeon pretends not to give importance to the deformity, exclusively using an advance Le Fort type osteotomy, with both functional and aesthetic treatment being limited. In this article, we give all the elements to perform this Le Fort III Modified Osteotomy in anterior Z, and that it is a combined and routine procedure in midface surgery.

Characteristics of the Sphenoid Bone in Crouzon Syndrome

BACKGROUND

The goal of this study is to analyze the safety of reconstructive surgeries for Crouzon syndrome, and to understand the deformities and complications related to the surgical procedure.

METHODS

Thirty-nine subjects underwent preoperative computed tomographic scans were included (Crouzon, n = 19; controls, n = 20) in this study. Craniofacial cephalometric measurements were analyzed by Materialise software.

RESULTS

The overall average distance from the pterygoid junction to the coronal plane in the patients with Crouzon syndrome was 21.34 mm (standard deviation [SD] 5.13), which was deeper than that in the controls by 35% (P = 0.000).The overall average distances between the left and right foramen ovale and pterion on the sphenoid bone in the subjects were 64.93 mm (SD 7.56) and 67.83 mm (SD 8.57), which were increased by 13% (P = 0.001) and 14% (P = 0.001) compared with those in the controls.The overall distances between the most inferior point of the left and right lateral pterygoid plate and the medial pterygoid plate in the subjects were 51.09 mm (SD 6.68) and 51.51 mm (SD 10.98), which was not statically different from the controls (P = 0.887, P = 0.991, respectively).

CONCLUSIONS

This study characterized the surgically relevant anatomy of the sphenoidal bone. The pterygomaxillary junction is located in the posterior of the skull. Though there are some anatomical differences due to age, it is well known that the cranial cavity of the sphenoid side is likely to be enlarged in Crouzon syndrome, which may contribute to the other complications of the disease.

Relationship between pterygomaxillary fissure morphology and maxillary/mandibular position : A cone beam computed tomography assessment

PURPOSE

The aim of this study was to investigate the possible correlation between maxillary and mandibular positioning via cephalometric analysis with pterygomaxillary fissure (PMF) morphology using cone beam computed tomography (CBCT).

METHODS

In this study, CBCT images from 825 individuals (448 female, 377 male; age range was 18-91 years with this cohort) were analyzed; PMF length and width were measured. Three-dimensional cephalometric analysis was also performed using cephalometric analysis software. The landmarks and measurements in relation to maxillary and mandibular positions were identified and performed for the cephalometric analysis. Analysis of variance (ANOVA) was used for comparison of the parameters, while the Bonferroni test was used for multiple comparisons. Pearson's test was also used to assess the correlations between the parameters.

RESULTS

The results showed that males had significantly larger PMF length (p < 0.001) and width (p < 0.001) compared to females. The mean PMF length was 17.7 mm (standard deviation [SD] 3.2 mm) for right and 17.7 mm (SD 3.3 mm) for left but were not significantly different (p > 0.05). In terms of the cephalometric measurements, a significant correlation was found between upper central incisor (U1toAperp2D) and posterior facial height (PostFaceHtSGo2D) and PMF length, while correlations were found between PMF width and several cephalometric parameters such as lower lip (LwLiptoEPln2D and LwLiptoHLine2D) and occlusal plane (OPtoFHAng2D) (p < 0.05).

CONCLUSION

A significant relationship was observed between PMF morphology and the position of the maxilla or mandible. PMF lengths and widths were larger in males than females. Posteroanterior maxillary and mandibular lengths and posterior facial height are associated with PMF length and width.

The pterygomaxillary junction: An imaging study for surgical information of LeFort I osteotomy

Maxillary osteotomy is a common surgical procedure and often involves separation of the pterygomaxillary junction (PMJ), which is a “blinded” procedure with inherent risks. Knowledge of the PMJ structure is essential. It remains unclear whether patients with different facial types have different PMJ structures, or different surgical outcome. This study evaluated the computed tomographic images of 283 consecutive patients who received orthognathic surgery. Patients were classified into Angle class I, II, III and cleft lip/palate groups. The results showed that the PMJ was 5.1 ± 1.4 mm in thickness, 9.7 ± 1.7 mm in width, and 102.0 ± 4.0 degrees relative to the sagittal plane in the level of posterior nasal spine. There were no statistically significant differences in these measurements among the groups. The class III group demonstrated significantly smaller angle relative to the maxillary occlusal plane. The cleft group showed significantly longer vertical distance between the posterior nasal spine and the lower border of PMJ, shorter distance between the second molar and PMJ, and longer distance between the descending palatine artery and PMJ. With regard to postoperative outcome, the cleft group showed higher incidence of pterygoid plate fracture. The results in this study provide additional surgical anatomic information.