Ideal Reference Lines for Assessment of Facial Asymmetry in Rhinoplasty Patients

The Isosceles Nasal Tip-Laser-Assisted Midline Assessment in Rhinoplasty

The accurate determination of the nasal tip's spatial location is crucial for achieving symmetry in rhinoplasty. Even minor deviations can result in asymmetrical lengths and configurations of the nostrils. Our approach centers on defining the nasal tip position by establishing the midline of the nasal base and projecting an isosceles triangle. This triangle, with the tip as the vertex and alar creases as angles, ensures symmetric sidewalls. The symmetry axis, derived from the isosceles triangle, guides the placement of the tip sidewalls and columella. To implement this, we use anatomical benchmarks such as the implantation of the nasal base and position of the alar creases, considering inherent facial asymmetries. We introduce a laser gadget as an auxiliary tool, projecting perpendicular lines to guide precise midline alignment. Marking specific points, including interbrow midpoint and alar creases, ensures accuracy. In the past 12 months, we applied this methodology in 247 rhinoplasty cases, observing improved outcomes and patient satisfaction. Our proposal of utilizing isosceles triangles provides a streamlined approach to achieving symmetry. The laser device, while beneficial, should be viewed as supportive rather than an absolute guiding measure.

A three-dimensional algorithm for precise measurement of human auricle parameters

Measurement of auricle parameters for planning and post-operative evaluation presents substantial challenges due to the complex 3D structure of the human auricle. Traditional measurement methods rely on manual techniques, resulting in limited precision. This study introduces a novel automated surface-based three-dimensional measurement method for quantifying human auricle parameters. The method was applied to virtual auricles reconstructed from Computed Tomography (CT) scans of a cadaver head and subsequent measurement of important clinically relevant aesthetical auricular parameters (length, width, protrusion, position, auriculocephalic angle, and inclination angle). Reference measurements were done manually (using a caliper and using a 3D landmarking method) and measurement precision was compared to the automated method. The CT scans were performed using both a contemporary high-end and a low-end CT scanner. Scans were conducted at a standard scanning dose, and at half the dose. The automatic method demonstrated significantly higher precision in measuring auricle parameters compared to manual methods. Compared to traditional manual measurements, precision improved for auricle length (9×), width (5×), protrusion (5×), Auriculocephalic Angle (5-54×) and posteroanterior position (23×). Concerning parameters without comparison with a manual method, the precision level of supero-inferior position was 0.489 mm; and the precisions of the inclination angle measurements were 1.365 mm and 0.237 mm for the two automated methods investigated. Improved precision of measuring auricle parameters was associated with using the high-end scanner. A higher dose was only associated with a higher precision for the left auricle length. The findings of this study emphasize the advantage of automated surface-based auricle measurements, showcasing improved precision compared to traditional methods. This novel algorithm has the potential to enhance auricle reconstruction and other applications in plastic surgery, offering a promising avenue for future research and clinical application.

Facial Asymmetry-Demystifying the Entity

Introduction/Background

Perfect facial symmetry has always been considered a hallmark of beauty, but, is almost elusive in nature. However, clinically evident skeletal facial asymmetry on the other hand is quite common, which can result from congenital deformities, developmental abnormalities, secondary to maxillofacial trauma and it is an entity maxillofacial surgeons deal with on a regular basis. Surgical correction of facial asymmetry is challenging, as it not only involves the correction of the skeletal asymmetry for an aesthetic outcome, but, also the improvement of the soft tissue drape and dental occlusal harmony. This results in rehabilitation of functional components of orofacial complex like speech, deglutition and phonation.

Objective

With this paper, we intend to throw a light on this challenging aspect of maxillofacial surgery, along with giving the next generation of maxillofacial surgeons a direction to explore the topic further.

Conclusion

Meticulous evaluation and diagnosis of the patient's problems with latest diagnostic methods like 3-dimensional imaging and surgical treatment with orthognathic surgery, gap arthroplasty or distraction osteogenesis, utilizing cutting edge 3-D virtual planning will result in better outcomes.This review will collate the information available in the literature, along with the authors' recommendations for better planning and execution of this challenging puzzle of facial asymmetry.

Facial asymmetry and midsagittal plane definition in 3D: A bias-free, automated method

Symmetry is a fundamental biological concept in all living organisms. It is related to a variety of physical and social traits ranging from genetic background integrity and developmental stability to the perception of physical appearance. Within this context, the study of human facial asymmetry carries a unique significance. Here, we validated an efficient method to assess 3D facial surface symmetry by best-fit approximating the original surface to its mirrored one. Following this step, the midsagittal plane of the face was automatically defined at the midpoints of the contralateral corresponding vertices of the superimposed models and colour coded distance maps were constructed. The method was tested by two operators using facial models of different surface size. The results show that the midsagittal plane definition was highly reproducible (maximum error < 0.1 mm or°) and remained robust for different extents of the facial surface model. The symmetry assessments were valid (differences between corresponding bilateral measurement areas < 0.1 mm), highly reproducible (error < 0.01 mm), and were modified by the extent of the initial surface model. The present landmark-free, automated method to assess facial asymmetry and define the midsagittal plane of the face is accurate, objective, easily applicable, comprehensible and cost effective.