Development of a maxillofacial virtual surgical system based on biomechanical parameters of facial soft tissue

Purpose

Lack of biomechanical force model of soft tissue hinders the development of virtual surgical simulation in maxillofacial surgery. In this study, a physical model of facial soft tissue based on real biomechanical parameters was constructed, and a haptics-enabled virtual surgical system was developed to simulate incision-making process on facial soft tissue and to help maxillofacial surgery training.

Methods

CT data of a 25-year-old female patient were imported into Mimics software to reconstruct 3D models of maxillofacial soft and skeletal tissues. 3dMD stereo-photo of the patient was fused on facial surface to include texture information. Insertion and cutting parameters of facial soft tissue measured on fresh cadavers were integrated, and a maxillofacial biomechanical force model was established. Rapid deformation and force feedback were realized through localized deformation algorithm and axis aligned bounding box (AABB)-based collision detection. The virtual model was validated quantitatively and qualitatively.

Results

A patient-specific physical model composed of skeletal and facial soft tissue was constructed and embedded in the virtual surgical system. Insertion and cutting in different regions of facial soft tissue were simulated using omega 6, and real-time feedback force was recorded. The feedback force was consistent with acquired force data of experiments conducted on tissue specimen. Real-time graphic and haptic feedback were realized. The mean score of the system performance was 3.71 given by surgeons in evaluation questionnaires.

Conclusion

The maxillofacial physical model enabled operators to simulate insertion and cutting on facial soft tissue with realization of realistic deformation and haptic feedback. The combination of localized deformation algorithm and AABB-based collision detection improved computational efficiency. The proposed virtual surgical system demonstrated excellent performance in simulation and training of incision-making process.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11548-022-02657-5.

Virtual Reality (VR) Simulation and Augmented Reality (AR) Navigation in Orthognathic Surgery: A Case Report

VR and AR technology have gradually developed to the extent that they could help operators in the surgical field. In this study, we present a case of VR simulation for preoperative planning and AR navigation applied to orthognathic surgery. The average difference between the preplanned data and the post-operative results was 3.00 mm, on average, and the standard deviation was 1.44 mm. VR simulation could provide great advantages for 3D medical simulations, with accurate manipulation and immersiveness. AR navigation has great potential in medical application; its advantages include displaying real time augmented 3D models of patients. Moreover, it is easily applied in the surgical field, without complicated 3D simulations or 3D-printed surgical guides.

Virtual Reality Simulation and Augmented Reality-Guided Surgery for Total Maxillectomy: A Case Report

With the improvement in computer graphics and sensors, technologies like virtual reality (VR) and augmented reality (AR) have created new possibilities for developing diagnostic and surgical techniques in the field of surgery. VR and AR are the latest technological modalities that have been integrated into clinical practice and medical education, and are rapidly emerging as powerful tools in the field of maxillofacial surgery. In this report, we describe a case of total maxillectomy and orbital floor reconstruction in a patient with malignant fibrous histiocytoma of the maxilla, with preoperative planning via VR simulation and AR-guided surgery. Future developments in VR and AR technologies will increase their utility and effectiveness in the field of surgery.

Assessment of a Novel Standardized Training System for Mandibular Contour Surgeries

Importance

Mandibular contour surgeries (MCS) involving reduction gonioplasty and genioplasty are rewarding for patients with square faces; however, the procedure has inherently difficult clinician learning curves and unpredictable skill acquisitions. To our knowledge, there has been no effective, validated training model that might improve training and surgical outcomes for MCS.

Objective

To establish and evaluate a standardized intraoral MCS training system.

Design, Setting, and Participants

Intraoral MCS training models were constructed by 3-dimensional (3D) skull models covered with elastic head cloths. From April 2016 to April 2018, 90 consecutive MCS patients (30 per group) and 15 craniofacial surgery fellow physicians (5 per group) were enrolled in the prospective observational study. They were randomly divided into intervention groups (A and B) and a control group (C). Intervention groups A and B completed 5 training sessions on the intraoral MCS training models before each clinical case. Group A performed both the model training sessions and clinical surgeries with surgical templates. Control group C had no extra training before clinical surgeries. All groups completed clinical surgery under supervision on 6 patients. The duration of follow-up was at least 3 months postoperatively.

Interventions

Intraoral MCS training models were provided to intervention groups (A and B) before clinical surgeries. Surgical templates were provided to intervention group A both in training sessions and clinical surgeries.

Main Outcomes and Measures

The completion time, surgical accuracy, learning curves, operating confidence, surgical skill, and outcome satisfaction of each procedure were recorded and analyzed with paired t test and 1-way analysis of variance test by blinded observers.

Results

All 90 patients (14 men, 76 women; mean [SD] age, 26 [5] years) were satisfied with their postoperative mandible contours. The intervention groups (A and B), especially the group with surgical templates (A) showed improvements in clinical surgery time (mean [SD], group A 147.2 [24.71] min; group B, 184.47 [16.28] min; group C, 219.3 [35.3] min; P = .001), surgical accuracy (mean [SD], group A, 0.68 [0.22] mm; group B, 1.22 [0.38] mm; group C, 1.88 [0.54] mm; P < .001), learning curves, and operators' confidence and surgical skill.

Conclusions and Relevance

The intraoral MCS training model was effective and practical. The optimal intraoral MCS training system included intraoral MCS training models and surgical templates. The system significantly decreased clinical surgery time, improved surgical accuracy, shortened the learning curve, boosted operators' confidence, and was associated with better acquisition of surgical skills.

Level of Evidence

NA.

An Effective Simulator for Intraoral Facial Skeletal Contour Surgeries

BACKGROUND

In East Asia, intraoral facial skeletal contour surgeries (intraoral FSCSs), including reduction gonioplasty, reduction malarplasty, and genioplasty, have become increasingly popular. Nonetheless, intraoral FSCSs are technically difficult and have a steep learning curve. An effective simulator could be beneficial for intraoral FSCS training. However, there is no intraoral FSCS simulator available. We introduced an intraoral FSCS simulator and assessed its effectiveness.

METHODS

An intraoral FSCS simulator was established by covering a 3-dimensional printed skull with elastic cloth. Twenty residents were enrolled and randomly divided into experimental group A and control group B. Group A performed the intraoral FSCS on the simulator for 3 times. Group B performed the intraoral FSCS on skull model for 3 times. The intraoral FSCS simulator and trainees' performance were evaluated by a trainee-reported questionnaire before and after training, the surgical outcomes were graded by 3 senior attending physicians. All questions and the surgical outcome were scored based on a 5-point Likert scale (1 = very poor, 5 = very good). The surgical times were recorded.

RESULTS

The intraoral FSCS simulator (4.13 ± 0.64) simulated the surgical reality significantly better than the skull (2.6 ± 0.63). In intraoral FSCS simulator training, the restriction and compliance of the facial soft tissue were vividly mimicked (4.4 ± 0.51); the intraoral approach was vividly mimicked (4.07 ± 0.59). The intraoral FSCS simulator is significantly superior to the skull in improving participants' confidence in performing intraoral FSCS, power system control, and intraoral approach adoption (<0.001). The average surgical outcome score was 3.11 ± 0.45 in group A and 3.91 ± 0.24 in group B. The average surgical time was 177.78 ± 28.38 minutes in group A and 65.26 ± 15.38 minutes in group B.

CONCLUSIONS

We developed the first intraoral FSCS simulator and proved its effectiveness preliminarily. Randomized controlled study with clinical cases is needed to further test its effectiveness.

Virtual Reality and Augmented Reality in Plastic Surgery: A Review

Recently, virtual reality (VR) and augmented reality (AR) have received increasing attention, with the development of VR/AR devices such as head-mounted displays, haptic devices, and AR glasses. Medicine is considered to be one of the most effective applications of VR/AR. In this article, we describe a systematic literature review conducted to investigate the state-of-the-art VR/AR technology relevant to plastic surgery. The 35 studies that were ultimately selected were categorized into 3 representative topics: VR/AR-based preoperative planning, navigation, and training. In addition, future trends of VR/AR technology associated with plastic surgery and related fields are discussed.