Three-Dimensional Soft Tissue Change of the Malar Region with High Le-Fort 1 Advancement: Implications for Aesthetic Malar Contouring

Three-dimensional soft tissue change of the malar region with high Le-Fort 1 advancement: Implications for aesthetic malar contouring

Goals/Purpose:

   While orthognathic procedures are performed for a number of clinical scenarios, a fundamental goal is to reposition the facial skeletal components so as to improve both function as well as aesthetics. For patients with malar hypoplasia, modification of the traditional Le Fort 1 osteotomy, the workhorse procedure for maxillary repositioning, allows one to carry the osteotomy superolaterally to advance the zygoma, and thereby simultaneously augment the malar region. With recent advances in three-dimensional (3D) imaging it is now possible to plan such three-dimensional skeletal movements preoperatively, to accurately execute these movements intraoperatively through customized cutting guides, and to 3-dimensionally quantify the resultant skeletal and soft tissue change. The goal of this study is to quantify the relationship between underlying skeletal change and overlying soft tissue change in the zygoma region for a series of patients who underwent high LeFort 1 osteotomy that included zygoma advancement.

   While soft tissue change has been related to the underlying skeletal movement for some facial areas (e.g. chin with genioplasty), this has not been well described for the malar region and this may relate to the high revision rates for malar alloplastic augmentation cited in the literature. It is possible that data acquired through this study can be applied in the context of planning malar augmentation and reduction procedures.

Methods/Technique:

   For 5 consecutive patients who underwent high LeFort 1 osteotomy with zygomaticomaxillary advancement, preoperative and late postoperative cone-beam CT studies were compared using MIMICS (Materialise NV, Leuvon, Belgium) and Simplant Pro (Materialise Dental NV, Leuvon, Belgium) software.  Quantitative change was measured using three different parameters:  volumetric change, contour change, and landmark spatial position change. Soft tissue change overlying the zygoma was quantified along the underlying osteotomy line at key skeletal landmarks (eg. directly below the infraorbital foramen).  Preoperative and late postoperative 3D photos (3DMD, Atlanta, GA) were also compared.

Results/Complications:

   Soft tissue change in the cheek paralleled the direction of zygomatic skeletal movement. At the level of the osteotomy and directly inferior to the infraorbital foramen, the ratio of soft tissue to skeletal advancement was between 0.4 and 0.5.  At this same level, for a skeletal advancement of 7 mm., a 3 mm decrease in thickness of the overlying soft tissue envelope was noted.

Figures 1 through 5 demonstrate the findings for the landmark spatial position change analysis for a representative case. Figures 1 (left) and 2 (right) demonstrate the postoperative 3D CT scan. The hardware is seen as blue and the green vertical line demonstrates the sagittal plane of study. Figure 3 demonstrates the superimposition of the red (preoperative) with grey (postoperative) scans with regards to the cranial base. Figures 4 (left) and 5 (right) demonstrate the skeletal change with overlying soft tissue change along the sagittal plane designated in Figures 1 and 2, respectively. Again note that presurgical skeletal and soft tissue contour is in red, and postsurgical in grey.

Conclusion:

For this group of patients, soft tissue change in the upper face was quantitatively related to underlying zygomatic advancement using multiple 3D parameters. This data augments the existing literature in how soft tissue behaves with skeletal change for this particular area of the face (malar region). More specifically in the plane of the mental foramen we noted a ratio of 0.4 to 0.5 for soft tissue to skeletal change with advancement. With this there was some attenuation of the soft tissue layer. This study provides outcome data that our group now considers in tailoring the high Le Fort 1 osteotomy in subsequent patients based on their preoperative clinical findings. Finally this data may be useful for those surgeons performing malar augmentation with alloplastic implants (choosing implant size, shape, and position to achieve the intended soft tissue aesthetic goal).

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