Application of a virtual and mixed reality-navigation system using commercially available devices to the lateral temporal bone resection.

BACKGROUND: Lateral temporal bone resection (LTBR) is performed for stage T1-2 external ear malignant tumors and requires spatial anatomical knowledge of the rare surgical field. OBJECTIVE: This paper presents a novel virtual reality (VR) based surgical simulation and navigation system using only commercially available display device and an online software, to assist in the understanding of the anatomy pre and intraoperatively. RESULT AND CONCLUSION: VR model created by 3D Slicer modules and visualized on head mounted display enabled users to simulate and learn surgical techniques of a rare surgical case. 3D hologram through HoloLens assisted the surgeon in comprehending the spatial relationship between crucial vital structures and the pathological lesion during the operation. This platform does not require the users to possess specific programming skill or knowledge, and is therefore applicable in daily clinical usage.

Patient-specific virtual and mixed reality for immersive, experiential anatomy education and for surgical planning in temporal bone surgery.

OBJECTIVE: The recent development of extended reality technology has attracted interest in medicine. We explored the use of patient-specific virtual reality (VR) and mixed reality (MR) temporal bone models in anatomical teaching, pre-operative surgical planning and intra-operative surgical referencing. METHODS: VR and MR temporal bone models were created and visualized on head-mounted display (HMD) and MR headset respectively, by a novel webservice that allows users to convert computed tomography images to VR and MR images without specific knowledge of programming. Eleven otorhinolaryngology trainees and specialists were asked to manipulate the healthy VR temporal bone model and to assess its validity by filling out a questionnaire. Additionally, VR and MR pathological models of petrous apex cholesteatoma were utilized for surgical planning pre-operatively and for referring to the anatomy during the surgery. RESULTS: Most participants were favorable about the VR model and considered HMD as superior to a flat computer screen. 91% of the participants agreed or somewhat agreed that VR through HMD is cost effective. In addition, the VR pathological model was used for planning and sharing the surgical approach during a pre-operative surgical conference. The MR headset was worn intra-operatively to clarify the relationship between the pathological lesion and vital anatomical structures. CONCLUSION: Regardless of the participants' training level in otorhinolaryngology or VR experience, all participants agreed that the VR temporal bone model is useful for anatomical education. Furthermore, the creation of patient-specific VR and MR models using the webservice and their pre- and intra-operative usages indicated the potential of innovative adjunctive surgical instrument.

The progress of medication-related osteonecrosis of the jaw with conservative initial treatment: A 12-year retrospective study of 129 patients.

This retrospective study aimed to examine the course and prognosis of medication-related osteonecrosis of the jaw (MRONJ) initially treated conservatively and the effects of various factors affecting treatment outcomes. We evaluated 129 patients with MRONJ between January 2008 and December 2018 at a university hospital. The factors examined included sex, age, stage of MRONJ (1-3), type of bone modifying agents (bisphosphonate or denosumab), primary disease (osteoporosis or malignant tumor), medical history (diabetes and rheumatoid arthritis), use of corticosteroids, the trigger of MRONJ (teeth extraction or others), and separation of sequestrum, using logistic regression analysis. Patients with MRONJ were treated conservatively as the initial treatment in accordance with the position paper of the American Association of Oral and Maxillofacial Surgeons. Of the 129 patients, 59 (45.7%) were cured, and the condition of 70 (54.3%) remained unchanged or worsened. The overall cure rates at 12, 36, and 60 months were 25.8%, 50.8%, and 72.4% respectively. The cure rate of stage 1 was lower than that of stages 2 and 3 at 80 months. In multivariate analysis, it was found that 37 (64.9%) of 57 patients with osteoporosis as a primary disease were cured (odds ratio [OR], 7.7; 95% confidence interval [CI], 2.4-24.4). In addition, 40 (69.0%) of 58 patients with separation of sequestrum were cured (OR, 8.9; 95% CI, 3.4-23.5). The cure rate was significantly higher in patients with osteoporosis than in those with cancer when the treatment outcomes of primary disease were compared using the Kaplan-Meier method (p < 0.01). It was also significantly higher in patients who had separation of sequestrum than in those who did not (p < 0.05). Our results suggest that primary disease and separation of sequestrum were associated with favorable outcomes in patients with MRONJ initially treated conservatively. MRONJ had a poor prognosis with conventional treatment carried according to the stage of the disease. This was especially prominent when conservative treatment was employed for mild cases.