Division of Plastic and Reconstructive Surgery, Department of Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, USA.
Neural Engineering and Precision Surgery Laboratories (NEPS), Mayo Clinic, Rochester, MN, USA.
Aesthetic Plast Surg. 2024 Nov;48(21):4272-4279. doi: 10.1007/s00266-024-04300-x. Epub 2024 Aug 26.
In gender-affirming surgery, facial skeletal dimorphism is an important topic for every craniofacial surgeon. Few cephalometric studies have assessed this topic; however, they fall short to provide skeletal contour insights that direct surgical planning. Herein, we propose statistical shape modeling (SSM) as a novel tool for investigating mandibular dimorphism for young white individuals.
A single-center, retrospective study was performed using computed tomography (CT) scans of white individuals, aged 20 to 39 years old. AI-assisted, three-dimensional (3D) mandibles were reconstructed in Materialise Mimics v25.0. We used SSM to generate average 3D models for both genders. Relevant manual anthropometric measurements were taken for the SSMs and individual mandibles. Contour disparities were then represented using 3D overlays and heatmaps. Statistical analyses were performed using unpaired student t testing or Wilcoxon signed rank testing with 95% confidence interval as deemed appropriate by population-level normality assessment.
Ninety-eight patients (53 females, 45 males) were included. Male mandibles showed greater bigonial width, intercondylar width, ramus height, and body length [p<0.005]. There was no statistically significant difference in the gonial angle measurements [p=0.62]. All relevant manual individual measurements demonstrated excellent concordance to their SSM counterparts. The 3D overlays of SSMs revealed squarer male chins with more lateral but less anterior projection than their female counterparts. Also, the female mandibles showed smoother transition at the gonial angle.
SSM provides a novel tool to objectively evaluate volumetric and contour dimorphisms between genders. Moreover, this method can be automated, allowing for expedited comparisons between populations of interest compared to manual assessment.
This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 . Bullet points about the importance of this work: Advancing Anthropometric Assessment: Statistical shape modeling (SSM) offers a cutting-edge approach to visualizing gender-specific skeletal anatomic differences for aesthetic and gender-affirming facial surgery. Expediting Comparative Analysis: The workflow established in this paper streamlines the evaluative process, enabling rapid morphologic comparisons between populations. Patient-Centered Care: This study establishes a foundation for the development of SSMs in individualized operative planning.
在性别肯定手术中，面部骨骼二态性是每位颅面外科医生的重要课题。很少有头影测量研究评估这个课题;然而，它们未能提供指导手术规划的骨骼轮廓见解。在此，我们提出统计形状建模 (SSM) 作为一种新工具，用于研究年轻白人个体的下颌骨二态性。
使用年龄在 20 至 39 岁的白人个体的计算机断层扫描 (CT) 进行单中心回顾性研究。在 Materialise Mimics v25.0 中使用 AI 辅助重建三维 (3D) 下颌骨。我们使用 SSM 为两性生成平均 3D 模型。为 SSM 和个体下颌骨进行了相关的手动人体测量学测量。然后使用 3D 叠加和热图表示轮廓差异。使用未配对学生 t 检验或 Wilcoxon 符号秩检验进行统计分析，并根据群体水平正态性评估适当使用 95%置信区间。
共纳入 98 例患者(53 例女性，45 例男性)。男性下颌骨的双颌宽度、髁间宽度、髁突高度和体长度较大[P<0.005]。下颌角测量无统计学差异[P=0.62]。所有相关的手动个体测量值与 SSM 对应物具有极好的一致性。SSM 的 3D 叠加显示男性下巴更方，侧面更突出，但前部投影较少，而女性下巴在下颌角处的过渡更平滑。
SSM 提供了一种新的工具，可客观评估性别之间的体积和轮廓二态性。此外，与手动评估相比，这种方法可以自动化，从而加快对感兴趣人群的比较。
证据水平 III：本杂志要求作者为每篇文章分配一个证据水平。有关这些循证医学评级的完整说明，请参阅目录或在线作者指南 www.springer.com/00266 。关于这项工作重要性的要点：推进人体测量评估：统计形状建模 (SSM) 为美学和性别肯定面部手术提供了一种可视化性别特定骨骼解剖差异的前沿方法。加快比较分析：本文建立的工作流程简化了评估过程，能够在人群之间快速进行形态比较。以患者为中心的护理：本研究为 SSM 在个体化手术计划中的发展奠定了基础。
