Development of a virtual reality-based zygomatic implant surgery training system with global collision detection and optimized finite element method model

BACKGROUND AND OBJECTIVE

Zygomatic implant surgery is challenging due to the complex structure of the zygomatic bone, limited visual range during surgery, and lengthy implant path. Moreover, traditional training methods are costly, and experimental subjects are scarce.

METHODS

To overcome these challenges, we propose a novel training system that integrates visual, haptic, and auditory feedback to create a more immersive surgical experience. The system uses dynamic bounding volume hierarchy (BVH) and Symplectic Euler to detect global collisions between surgical tools and models, while an optimized finite element method (FEM) model simulates soft tissue and detects collisions. Compared to previous works, our system achieves global rigid-body collisions between surgical tools and patient models, while also providing stable and realistic simulation and collisions of soft tissues. This advancement offers a more realistic simulation for zygomatic implant surgery.

RESULTS

We conducted three experiments and evaluations. The first experiment measured the axial force generated during the zygomatic implant simulation process and compared it with actual surgery, demonstrating the realistic force rendering feedback of our system. The second evaluation involved 15 novice surgeons who experienced the system and completed a questionnaire survey focusing on five aspects. The results showed satisfactory evaluations. The third experiment involved six surgeons who underwent in-depth training for two hours daily and were tested on the first, third, and fifth days. We collected data and combined it with the doctors' feedback to prove that our system can improve surgeons' proficiency in zygomatic implant surgery and provide a novel training solution for this procedure.

CONCLUSION

We have innovatively integrated global collision detection and optimized soft tissue simulation into our system. Furthermore, we have conducted experimental validation to demonstrate the effectiveness of this implementation. We present a novel solution for zygomatic implant surgery training.

Surgical Strategy for Recurrent Giant Cell Tumor in the Thoracolumbar Spine

OBJECTIVE

Recurrent giant cell tumor (RGCT) of the spine represents a clinical challenge for surgeons, and the treatment strategy remains controversial. This study aims to describe the long-term follow-up outcomes and compare the efficacy of en bloc spondylectomy versus piecemeal spondylectomy in treating RGCT of the thoracolumbar spine.

METHODS

A total of 32 patients with RGCT of the thoracolumbar spine treated from June 2012 to June 2019 were retrospectively reviewed. A total of 15 patients received total en bloc spondylectomy (TES) with wide or marginal margin while 17 patients received total piecemeal spondylectomy (TPS) with intralesional margin. Postoperative Eastern Cooperative Oncology Group Performance Score (ECOG-PS), Frankel classification and recurrence-free survival (RFS) were evaluated after surgery. Survival curves were estimated by the Kaplan-Meier method and differences were analyzed with the log-rank test. Multivariate analysis was performed with Cox regression to identify the independent prognostic factors affecting RFS.

RESULTS

During a median follow-up of 41.9 ± 17.5 months, all patients with compromised neurologic functions exhibit significant improvement, with the mean ECOG-PS decreasing from 1.5 ± 1.3 to 0.13 ± 0.3 (p < 0.05). Among the 17 patients treated with TPS, eight patients developed local recurrence after a median time of 15.9 ± 6.4 months and four patients died from progressive disease. On the other hand, local recurrence were well managed with TES, since only one out of 15 patients experienced local relapse and all patients are alive with satisfied function at the latest follow-up. The median RFS for patients receiving TES and TPS are 75.0 months (95% CI: 67.5-82.5 m) and 38.3 months (95% CI: 27.3-49.3 m) respectively (p = 0.008). Multivariate analysis shows that the Ki67 index (p = 0.016), resection mode (p = 0.022), and denosumab (p = 0.039) are independent risk factors affecting RFS.

CONCLUSIONS

TES with wide/marginal margin should be offered to patients with RGCT whenever feasible, given its long-term benefits in local control and symptom alleviation. Additionally, patients with lower Ki67 index and application of denosumab tend to have a better prognosis.

An innovative virtual reality training tool for the pre-hospital treatment of cranialmaxillofacial trauma

Virtual reality (VR) surgery using the High Technology Computer Corporation Very Immersive Virtual Experience professional 2(HTC VIVE Pro2) suite is a multi-sensory, holistic surgical training experience. A multimedia combination including videos and three-dimensional interaction in VR has been developed to enable trainees to experience a realistic battlefield environment. The innovation allows trainees to interact with the individual components of the cranialmaxillofacial(CMF) anatomy and apply surgical instruments while watching close-up stereoscopic three-dimensional videos of the surgery. In this study, a novel training tool for the pre-hospital treatment of CMF trauma based on immersive virtual reality (iVR) was developed and validated. Twenty-five CMF surgeons evaluated the application for face and content validity. Using a structured assessment process, the surgeons commented on the content of the developed training tool, its realism and usability and the applicability of VR surgery for CMF trauma rescue simulation training. The results confirmed the applicability of VR for delivering training in the pre-hospital treatment of CMF trauma. Modifications were suggested to improve the user experience and interactions with the surgical instruments. This training tool is ready for testing with surgical trainees.

A Novel Free-hand Technique of Pedicle Screw Placement in the Lumbar Spine: Accuracy Evaluation and Preliminary Clinical Results

OBJECTIVE

Pedicle screw implantation is the most common technique to achieve stability during spinal surgeries. Current methods for locating the entry point do not have a quantified criteria and highly rely on the surgeons' experience. Therefore, we aim to propose a quantified pedicle screw placement technique in the lumbar spine and to investigate its accuracy and safety in clinical practice.

METHODS

We conducted a retrospective study involving 110 patients who received spinal surgery in our hospital from August 2018 to August 2021. All patients included had herniation of a single lumbar disc and were consistently treated with posterior discectomy, inter-body fusion, and transpedicular internal fixation. For 54 patients in the observation group, the pedicle screws were placed with our technique, which is located at 4 mm below the superior edge of the transverse process in line with the lateral margin of the superior articular process. For 56 patients in the control group, pedicle screws were placed according to the traditional crista lambdoidalis method. Comparisons were made in terms of the operation time, blood loss, time for exposure, the accuracy of placement, and postoperative complications. Furthermore, we applied our method to 64 patients with indistinguishable crista lambdoidalis and evaluated the accuracy of screw placement and clinical outcomes according to the visual analogue scale (VAS) and the Japanese Orthopaedic Association (JOA) score.

RESULTS

There was no significant difference in intraoperative bleeding, accuracy of placement, and postoperative complications between our technique and the traditional crista lambdoidalis method (P > 0.05). However, the exposure time before screw placement (12.8 ± 0.3 vs. 17.4 ± 0.3, P = 0.001) and the total surgery time (97.2 ± 1.9 vs 102.3 ± 0.9, P = 0.020) were significantly shortened with our method. Additionally, in cases with indistinguishable crista lambdoidalis, our technique showed satisfying accuracy, with 97.6% screws placed in appropriate trajectory on the first attempt and all screws eventually positioned in the safe zone according to the Gertzbein-Robbins grading. All patients experienced steady improvement after surgery.

CONCLUSION

Placing pedicle screws at 4 mm below the superior edge of the transverse process in line with the lateral margin of the superior articular process is a viable pedicle screw placement method. With this method, we observed a higher success rate and shorter operation time. In addition, this method can be applied in cases with indistinguishable crista lambdoidalis, and have satisfied success rate and clinical outcome.

Current research and management of undifferentiated pleomorphic sarcoma/myofibrosarcoma

Undifferentiated pleomorphic sarcoma (UPS), once termed as malignant fibrous histiocytoma, has always been diagnosed exclusively in clinical practice because it lacks any defined resemblance to normal mesenchymal tissue. Although myxofibrosarcoma (MFS) has been separated from UPS due to its fibroblastic differentiation with myxoid stroma, UPS and MFS are still identified as a sarcoma group in terms of molecular landscapes. In this review article, we will describe the associated genes and signaling pathways involved in the process of sarcoma genesis and make a summary of conventional management, targeted therapy, immunotherapy, and some novel potential treatments of UPS/MFS. With the progressive advancements in medical technology and a better understanding about the pathogenic mechanism of UPS/MFS in the coming decades, new lights will be shed on the successful management of UPS/MFS.

Symptomatic spinal metastases from neuroendocrine neoplasms: surgical outcomes and prognostic analysis

OBJECTIVES

In this article, we investigated the efficiency of surgery in treating symptomatic spinal metastases from neuroendocrine neoplasms and performed univariate analysis for identification of possible prognostic factors.

METHODS

A retrospective study was performed, enrolling a total of 19 patients who received surgeries in our center for symptomatic spinal metastases from neuroendocrine neoplasms (NEN). The Kaplan-Meier method was adopted to estimate overall survival (OS) and recurrence free survival (RFS). Univariate analysis was performed for identification of possible prognostic factors.

RESULTS

All patients recruited displayed stable recovery after surgical intervention, with a median OS of 27.3 months (95% Confidence Interval: 16.4-38.1 months) and a median RFS of 23.0 months (95% Confidence Interval: 12.1-33.8 months). Postoperatively, 15 patients exhibited improved neurological function based on the Frankel classification, while 16 patients experienced significant pain relief, with mean visual analog scale (VAS) score decreasing from 7.47 ± 2.32-2.47 ± 1.25 (p < 0.05). Univariate analysis revealed that the presence of visceral metastases (p = 0.034) and extraspinal bone metastases (p = 0.016) are both related with poor prognosis. Additionally, well histologic differentiation (p = 0.010) and administration of postoperative octreotide (p = 0.041) or bisphosphonate (p = 0.023) are all indicators for better outcome.

CONCLUSIONS

Surgery is an efficient option for treating symptomatic spinal metastases from NEN due to its immediate and assured benefits in pain alleviation, restoration of function and stability reconstruction.

Surgical outcomes and prognostic factors for patients with gastric cancer spinal metastasis

Purpose

To investigate the outcome and prognostic factors of surgery in treating gastric cancer spinal metastasis (GCSM).

Patients and methods

A total of 17 patients with GCSM who have undertaken spinal surgeries have been identified. Kaplan–Meier method and univariate analysis are adopted to investigate the prognostic factors affecting overall survival (OS) and progression-free survival (PFS).

Results

The median PFS and OS are 11.3 months (95% CI: 7.8–14.9 months) and 11.9 months (95% CI: 8.4–15.4 months), respectively. Postoperatively, all patients had substantial pain relief, with mean visual analog scale score descending from 6.6±1.6 to 3.4±1.2. Meanwhile, patients also showed improved neurological functions, with 8 of them having improvements of at least one level in Frankel classification. Univariate analysis presented that patients with carcinoembryonic antigen (CEA)<6 µg/L (p=0.020), lactate dehydrogenase (LDH)<300 U/L (p=0.012), alkaline phosphatase (ALP)<200 U/L (p=0.007), and Tokuhashi score>6 (p=0.027) show longer OS. Moreover, application of bone cement, low level of ALP (<200 U/L), and LDH (<300 U/L) are associated with longer PFS (p<0.05).

Conclusions

Surgery is an efficient option in treating GCSM, due to its efficacy in pain alleviation, function restoration, and stability reconstruction. Low levels of CEA, LDH, ALP, and high Tokuhashi score (>6) are all favorable factors for better OS, whereas low levels of LDH, ALP, and application of bone cement are related with longer PFS.

[Neoplasm-inhibiting effect and sensitivity-promoting effect of indomethacin in vitro]

OBJECTIVE

To explore an anti-tumor effect of indomethacin on human colon adenocarcinoma cell line HCT116, and its mechanism.

METHODS

MTT, agarose gel electrophoresis, TdT and flow cytometry were used to study cell proliferation and apoptosis.

RESULTS

Indomethacin significantly inhibited the proliferation of HCT116 cells and induced apoptosis with a "dose-time" dependent pattern. A synergic effect of inhibiting cancer cells proliferation was observed when combined with 5-Fu.

CONCLUSION

Inhibition of proliferation and induction of apoptosis contribute to the mechanisms for anti-tumor activity of indomethacin.

Human dose-excretion studies with the pyrethroid insecticide cyfluthrin: urinary metabolite profile following inhalation

1. Nine male volunteers were exposed to the pyrethroid insecticide cyfluthrin. The study was performed in an exposure room, where an aerosol containing cyfluthrin was sprayed to obtain atmospheres with mean cyfluthrin concentrations of 160 and 40 micrograms/m3. Four volunteers were exposed for 10, 30 and 60 min at 160 micrograms/m3 and another five volunteers were exposed for 60 min at 40 micrograms/m3. For 160 micrograms/m3 exposure urine samples were collected before and immediately after exposure as well as for the periods 1-2, 2-3, 3-4, 4-5, 5-6, 6-12 and 12-24 h after exposure. For 40 micrograms/m3 exposure urine samples were collected before and 2 h after exposure. 2. The main urinary cyfluthrin metabolites, cis-/trans-3-(2,2-dichlorovinyl)-2,2-dimethylycyclopropane carboxylic acid (DCCA) and 4-fluoro-3-phenoxybenzoic acid (FPBA), were determined. The limit of detection (LOD) for all metabolites was 0.0025 microgram in an urine sample of 5 ml (0.5 microgram/l). After inhalative exposure of 40 micrograms cyfluthrin/m3 air for 60 min, the amount of metabolites in urine collected in the first 2 h after exposure was less than the LOD, namely 0.14 microgram for cis-DCCA, 0.15-0.28 microgram for trans-DCCA and 0.12-0.23 microgram for FPBA. 3. Of the metabolites, 93% was excreted within the first 24 h (peak excretion rates between 0.5 and 3 h) after inhalative exposure of 160 micrograms/m3. The mean half-lives were 6.9 h for cis-DCCA, 6.2 h for trans-DCCA and 5.3 h for FPBA. 4. The mean trans-:cis-DCCA ratio was 1.9 for the time course as well as for each subject. 5. The amount of metabolites in urine depends on the applied dose, on the exposure time and shows interindividual differences.