Landmark-independent method to determine mid-sagittal plane (MSP) and its clinical application in craniomaxillofacial trauma

Publication date: Available online 20 February 2018
Source:Journal of Oral and Maxillofacial Surgery
Author(s): Xiaotian Lian, Jun Guo, Wei Zeng, Hai Qing, Rui Ju, Wei Tang
PurposeThe purpose of this study was to explore new landmark-independent methods suitable for determining the mid-sagittal plane (MSP) in patients with craniomaxillofacial trauma and its clinical application.MethodsPreoperative CT data of 25 patients with craniomaxillofacial trauma was imported into Mimics software to reconstruct three-dimensional (3D) skull model. In experimental group, MSP was determined by different landmarks that are clear, scattered and do not have displacement according to the types of the fracture. In the control group, MSP was determined by traditional landmark-dependent method based on Nasion (Na), posterior nasal spine (PNS) and anterior nasal spine (ANS). After virtual fracture reduction, facial symmetry was determined to verify the reliability of both landmark-dependent and landmark-independent methods.ResultsUsing landmark-independent method proposed in this study, the minimal, maximal and average registered distance between the skull model after reduction and the mirror skull model was 0.5531, 1.2065, and 0.8287mm, respectively. Using the traditional landmark-dependent method, the minimal, maximal and average registered distance between the skull model after reduction and the mirror skull model was 0.7914, 1.9415, and 1.2250mm, respectively. When the average distance of <1.5mm between the two registered models was set as the criteria for qualified fracture reduction, all the 25 cases in the experimental group had qualified reduction, while 9 cases in the control group had unqualified reduction (P<0.05).ConclusionCompared to traditional landmark-dependent system, landmark-independent method is more reliable in determining MSP in patients with craniomaxillofacial trauma. Selection of different landmarks in different types of fractures makes it more precise to reconstruct MSP and can guide virtual reduction of fracture more effectively, which lays the foundation for subsequent surgical navigation and guide plate printing. The method is easy to operate and appropriate for digital evaluation of surgery.



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