High accuracy of positioning custom triflange acetabular components in tumour and total hip arthroplasty revision surgery

Aims

Custom triflange acetabular components (CTACs) play an important role in reconstructive orthopaedic surgery, particularly in revision total hip arthroplasty (rTHA) and pelvic tumour resection procedures. Accurate CTAC positioning is essential to successful surgical outcomes. While prior studies have explored CTAC positioning in rTHA, research focusing on tumour cases and implant flange positioning precision remains limited. Additionally, the impact of intraoperative navigation on positioning accuracy warrants further investigation. This study assesses CTAC positioning accuracy in tumour resection and rTHA cases, focusing on the differences between preoperative planning and postoperative implant positions.

Methods

A multicentre observational cohort study in Australia between February 2017 and March 2021 included consecutive patients undergoing acetabular reconstruction with CTACs in rTHA (Paprosky 3A/3B defects) or tumour resection (including Enneking P2 peri-acetabular area). Of 103 eligible patients (104 hips), 34 patients (35 hips) were analyzed.

Results

CTAC positioning was generally accurate, with minor deviations in cup inclination (mean 2.7°; SD 2.84°), anteversion (mean 3.6°; SD 5.04°), and rotation (mean 2.1°; SD 2.47°). Deviation of the hip centre of rotation (COR) showed a mean vector length of 5.9 mm (SD 7.24). Flange positions showed small deviations, with the ischial flange exhibiting the largest deviation (mean vector length of 7.0 mm; SD 8.65). Overall, 83% of the implants were accurately positioned, with 17% exceeding malpositioning thresholds. CTACs used in tumour resections exhibited higher positioning accuracy than rTHA cases, with significant differences in inclination (1.5° for tumour vs 3.4° for rTHA) and rotation (1.3° for tumour vs 2.4° for rTHA). The use of intraoperative navigation appeared to enhance positioning accuracy, but this did not reach statistical significance.

Conclusion

This study demonstrates favourable CTAC positioning accuracy, with potential for improved accuracy through intraoperative navigation. Further research is needed to understand the implications of positioning accuracy on implant performance and long-term survival.

Image-Guided Navigation in Spine Surgery: From Historical Developments to Future Perspectives

Intraoperative navigation is critical during spine surgery to ensure accurate instrumentation placement. From the early era of fluoroscopy to the current advancement in robotics, spinal navigation has continued to evolve. By understanding the variations in system protocols and their respective usage in the operating room, the surgeon can use and maximize the potential of various image guidance options more effectively. At the same time, maintaining navigation accuracy throughout the procedure is of the utmost importance, which can be confirmed intraoperatively by using an internal fiducial marker, as demonstrated herein. This technology can reduce the need for revision surgeries, minimize postoperative complications, and enhance the overall efficiency of operating rooms.

Near-Infrared Fluorescence Probe for Monoamine Oxidase A with a Large Stokes Shift for Intraoperative Navigation

Monoamine oxidase A (MAO-A) is a dimeric flavoprotein that is found in the mitochondrial membrane. Currently, there is a lack of near-infrared fluorescent probes (NIR-FPs) with good specificity and high sensitivity for detecting MAO-A, making it difficult to accurately recognize and image cells in vitro and in vivo. In this study, the NIR-FP DDM-NH2 was designed and synthesized in order to detect MAO-A specifically in live biological systems. The probe comprised two functional components: dicyanoisophosphone as an NIR dye precursor and alanine as a recognition moiety. After identifying MAO-A, the probe exhibited an NIR emission peak at 770 nm with a significant Stokes shift (180 nm), 11-fold response factor, low detection limit of 99.7 nM, and considerably higher affinity toward MAO-A than that toward MAO-B, indicating high sensitivity. In addition, DDM-NH2 was effective when applied to the image-based assessment of MAO-A activity in HeLa cells, zebrafish, and tumor-bearing mice, demonstrating great potential for visualization-based research and MAO-A application in vivo.

The application of extended reality technology-assisted intraoperative navigation in orthopedic surgery

Extended reality (XR) technology refers to any situation where real-world objects are enhanced with computer technology, including virtual reality, augmented reality, and mixed reality. Augmented reality and mixed reality technologies have been widely applied in orthopedic clinical practice, including in teaching, preoperative planning, intraoperative navigation, and surgical outcome evaluation. The primary goal of this narrative review is to summarize the effectiveness and superiority of XR-technology-assisted intraoperative navigation in the fields of trauma, joint, spine, and bone tumor surgery, as well as to discuss the current shortcomings in intraoperative navigation applications. We reviewed titles of more than 200 studies obtained from PubMed with the following search terms: extended reality, mixed reality, augmented reality, virtual reality, intraoperative navigation, and orthopedic surgery; of those 200 studies, 69 related papers were selected for abstract review. Finally, the full text of 55 studies was analyzed and reviewed. They were classified into four groups-trauma, joint, spine, and bone tumor surgery-according to their content. Most of studies that we reviewed showed that XR-technology-assisted intraoperative navigation can effectively improve the accuracy of implant placement, such as that of screws and prostheses, reduce postoperative complications caused by inaccurate implantation, facilitate the achievement of tumor-free surgical margins, shorten the surgical duration, reduce radiation exposure for patients and surgeons, minimize further damage caused by the need for visual exposure during surgery, and provide richer and more efficient intraoperative communication, thereby facilitating academic exchange, medical assistance, and the implementation of remote healthcare.

Freehand Technique for Pedicle Screw Placement during Surgery for Adolescent Idiopathic Scoliosis Is Associated with Less Ionizing Radiation Compared to Intraoperative Navigation

PURPOSE

We aim to compare radiation exposure and implant-related complications of the freehand (FH) technique versus intraoperative image-guided navigation (IN) for pedicle screw placement in adolescent idiopathic scoliosis (AIS) and estimate associated lifetime attributable cancer risks.

METHODS

A retrospective analysis of prospectively collected data from 40 consecutive AIS patients treated with pedicle screw instrumentation using the FH technique was performed. The dose area product (DAP) and effective dose (ED) were calculated. Screw-related complications were analysed, and the age- and gender-specific lifetime attributable cancer risks were estimated. The results were compared to previously published data on IN used during surgery for AIS.

RESULTS

There were no implant-related complications in our cohort. Implant density was 86.6%. The mean Cobb angle of the main curve was 75.2° (SD ± 17.7) preoperatively and 27.7° (SD ± 10.8) postoperatively. The mean ED of our cohort and published data for the FH technique was significantly lower compared to published data on the IN technique (p < 0.001). The risk for radiogenic cancer for our FH technique AIS cohort was 0.0014% for male patients and 0.0029% for female patients. Corresponding risks for IN were significantly higher (p < 0.001), ranging from 0.0071 to 0.124% and from 0.0144 to 0.253% for male and female patients, respectively.

CONCLUSION

The routine use of intraoperative navigation in AIS surgery does not necessarily reduce implant-related complications but may increase radiation exposure to the patient.

Custom CAD/CAM Peek Implants for Complex Orbitocranial Reconstruction: Our Experience with 15 Patients

Bone defects within the cranio-orbital complex present unique challenges in terms of surgical planning and reconstruction. This article presents a novel approach using PEEK material and advanced surgical technologies to address these challenges. A retrospective analysis of 15 patients who underwent craniofacial reconstruction using patient-specific polyetheretherketone (PEEK) implants between 2016 and 2021 was carried out. Comprehensive preoperative planning was performed, utilizing advanced imaging techniques and specialized software for virtual surgical planning. Patient-specific PEEK PSIs were designed and manufactured based on the preoperative plan. Intraoperative navigation was used to guide the surgical procedure, enabling precise osteotomy and optimal implant placement. This article describes the step-by-step process and the tools utilized in each phase. The etiologies were as follows: meningioma in seven cases, benign lesions in five cases, malignant tumors in two cases, and trauma sequelae in one case. In all cases, 3D-printed PEEK implants were utilized to achieve precise reconstruction. No major complications were described. In one case, an implant replacement was needed with successful outcomes. Our study demonstrates the feasibility and effectiveness of using PEEK patient-specific implants for personalized craniofacial reconstruction. The combination of advanced imaging, virtual planning, and CAD-CAM technology contributes to improved surgical outcomes in terms of oncologic margin control, functional restoration, and aesthetic results.

Mixed reality in primary retroperitoneal tumour surgery: Evaluation of preoperative and intraoperative application value

OBJECTIVE

To evaluate the feasibility and application value of mixed reality technology (MR) in Primary retroperitoneal tumour (PRT) surgery.

METHODS

From 276 patients who underwent PRT resection at the First Affiliated Hospital of Xi'an Jiaotong University, we screened 46 patients who underwent MR-assisted retroperitoneal tumour resection and 46 patients who underwent tumour resection without MR assistance. The intraoperative and postoperative recovery of the patients in both groups were compared, and the reliability and validity of the application of MR were further examined using the Likert scale.

RESULTS

There was a significant difference in the mean intraoperative bleeding volume between the two groups, but it was reduced in the MR group. The results of the Likert scale showed higher scores in the MR group than non-MR group.

CONCLUSIONS

MR can be used to assist PRT resection and has great potential to improve the rate of complete retroperitoneal tumour resection.

Augmented reality-assisted navigation system contributes to better intraoperative and short-time outcomes of laparoscopic pancreaticoduodenectomy: a retrospective cohort study

BACKGROUND

Augmented reality (AR)-assisted navigation system are currently good techniques for hepatectomy; however, its application and efficacy for laparoscopic pancreatoduodenectomy have not been reported. This study sought to focus on and evaluate the advantages of laparoscopic pancreatoduodenectomy guided by the AR-assisted navigation system in intraoperative and short-time outcomes.

METHODS

Eighty-two patients who underwent laparoscopic pancreatoduodenectomy from January 2018 to May 2022 were enrolled and divided into the AR and non-AR groups. Clinical baseline features, operation time, intraoperative blood loss, blood transfusion rate, perioperative complications, and mortality were analyzed.

RESULTS

AR-guided laparoscopic pancreaticoduodenectomy was performed in the AR group ( n =41), whereas laparoscopic pancreatoduodenectomy was carried out routinely in the non-AR group ( n =41). There was no significant difference in baseline data between the two groups ( P >0.05); Although the operation time of the AR group was longer than that of the non-AR group (420.15±94.38 vs. 348.98±76.15, P <0.001), the AR group had a less intraoperative blood loss (219.51±167.03 vs. 312.20±195.51, P =0.023), lower blood transfusion rate (24.4 vs. 65.9%, P <0.001), lower occurrence rates of postoperative pancreatic fistula (12.2 vs. 46.3%, P =0.002) and bile leakage (0 vs. 14.6%, P =0.026), and shorter postoperative hospital stay (11.29±2.78 vs. 20.04±11.22, P <0.001) compared with the non-AR group.

CONCLUSION

AR-guided laparoscopic pancreatoduodenectomy has significant advantages in identifying important vascular structures, minimizing intraoperative damage, and reducing postoperative complications, suggesting that it is a safe, feasible method with a bright future in the clinical setting.

The use of intraoperative CT navigation for posterior cervical spine foraminotomy

OBJECTIVES

Posterior cervical foraminotomy is a surgical procedure used to treat unilateral cervical radiculopathy. It provides direct decompression of the nerve root without the necessity of fusion while maintaining cervical mobility. With the advancement in image-guidance technology and minimal access techniques, intra-operative CT has provided a safer, more accurate instrumentation placement with less radiation exposure to operative staff and provides better anatomical visualization quality compared to traditional intra-operative imaging techniques. This case series aims to address the applications of advanced image guidance in posterior cervical foraminotomy and describe the nuances.

METHOD

A technical report on a series of seven cases on intraoperative CT navigation for posterior cervical foraminotomy surgery. Posterior cervical foraminotomy was performed in all patients under CT guided navigation system without an image intensifier. In one case after the foraminotomy, the extruded disc was carefully removed by gentle retraction.

RESULT

From 1 January 2020 to 31 December 2021, a total of seven patients with nine cervical foraminotomy procedures were performed using the aid of CT-guided navigation. The series comprised five women and two men whose mean age was 50.6 years. In all cases, the radiculopathy symptoms were diminished significantly. There were no cases of instability on the dynamic cervical radiograph. There were no complications during the surgical procedure.

CONCLUSION

The navigation also allows the surgeon to localise the index level accurately and appraise the adequacy of the intended decompression in three planes of the CT scan image. The ability to perform accurate spine navigation would be the precursor for robotic spinal surgery.

The Feasibility of 3D Intraoperative Navigation in Lateral Lumbar Interbody Fusion: Perioperative Outcomes, Accuracy of Cage Placement and Radiation Exposure

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To evaluate perioperative outcomes, accuracy of cage placement and radiation exposure in lateral lumbar interbody fusion (LLIF) using 3D intraoperative navigation (ION), compared to conventional 2D fluoroscopy only.

METHODS

The perioperative outcomes and accuracy of cage placement were examined in all patients who underwent LLIF using ION (ION group) or fluoroscopy only (non-ION group) by a single surgeon. The radiation exposure was examined in patients who underwent stand-alone LLIF.

RESULTS

A total of 87 patients with 154 levels (ION 49 patients with 79 levels/ non-ION 38 patients with 75 levels) were included. There were no significant differences in operative time (ION 143.5 min vs. non-ION 126.0 min, P = .406), time from induction end to surgery start (ION 31.0 min vs. non-ION 31.0 min, P = .761), estimated blood loss (ION 37.5 ml vs. non-ION 50.0 ml, P = .351), perioperative complications (ION 16.3% vs. non-ION 7.9%, P = .335) and length of stay (ION 50.6 hours vs. non-ION 41.7 hours, P = .841). No significant difference was found in the accuracy of cage placement (P = .279). ION did not significantly increase total radiation dose (ION 51.0 mGy vs. non-ION 47.4 mGy, P = .237) and tended to reduce radiation dose during the procedure (ION 32.2 mGy vs. non-ION 47.4 mGy, P = .932).

CONCLUSIONS

The perioperative outcomes, accuracy of cage placement and radiation exposure in LLIF using ION were comparable to those using fluoroscopy only. The use of ION in LLIF was feasible, safe and accurate and may reduce radiation dose to the surgeon and surgical team.

[Application of extended reality technology for real-time navigation in clinical operation]

OBJECTIVE

To explore the application of extended reality (XR) technology in clinical surgeries for improving the success rate of surgeries.

METHODS

To assist the surgeons to better understand the location, size and geometric shape of the lesions and reduce potential radiation exposure in minimally invasive surgical navigation based on two-dimensional images, we constructed three-dimensional models based on CT data and used XR technology to achieve intraoperative navigation. An improved quaternion method was used to improve the accuracy of electromagnetic positioning, with which the system error of positioning accuracy was reduced to below 2 mm. A 5G network was used to optimize the server GPU programming algorithm, and real-time video stream coding strategy and network design were adopted to reduce data transmission jam and delay in the remote surgery network, which achieved an average delay of less than 60 ms. A Gaussian distribution deformation model was used to simulate collision detection and stress deformation of the tissues to achieve a tactile perception effect.

RESULTS AND CONCLUSION

The intraoperative navigation system based on XR technology allowed more accurate determination of the location of the lesions, effectively reduced the surgical risk, and avoided the risk of intraoperative radiation exposure. The low latency and high fidelity of 5G network achieved real-time interaction during the surgery to provide a technical basis for multi-terminal remote cooperative surgery. The combination of force feedback technology and XR technology enables the surgeons to conduct deep immersion preoperative planning and virtual surgery to improve the success rate of surgery and shorten the learning curve.

Near-infrared fluorophores methylene blue for targeted imaging of the stomach in intraoperative navigation

Near-infrared (NIR) fluorescence imaging-guided surgery is increasingly concerned in gastrointestinal surgery because it can potentially improve clinical outcomes. This new technique can provide intraoperative image guidance for surgical margin evaluation and help surgeons examine residual lesions and small tumors during surgery. NIR fluorophores methylene blue (MB) is a promising fluorescent probe because of its safety and intraoperative imaging in the clinic. However, whether MB possesses the potential to perform intraoperative navigation of the stomach and gastric tumors needs to be further explored. Therefore, the current study mainly validated MB's usefulness in animal models' intraoperative imaging of stomach and gastric tumors. NIR fluorophores MB can exhibit specific uptake by the gastric epithelial cells and cancer cells. It is primarily found that MB can directly target the stomach in mice. Interestingly, MB was applied for the NIR imaging of gastric cancer cell xenografts, suggesting that MB cannot specifically target subcutaneous and orthotopic gastric tumors in xenograft models. Thus, it can be concluded that MB has no inherent specificity for gastric tumors but specificity for gastric tissues. Apparently, MB-positive and negative NIR imaging are meaningful in targeting gastric tissues and tumors. MB is expected to represent a helpful NIR agent to secure precise resection margins during the gastrectomy and resection of gastric tumors.

Multi-b-value diffusion stretched-exponential model parameters correlate with MIB-1 and CD34 expression in Glioma patients, an intraoperative MR-navigated, biopsy-based histopathologic study

Background

To understand the pathological correlations of multi-b-value diffusion-weighted imaging (MDWI) stretched-exponential model (SEM) parameters of α and diffusion distribution index (DDC) in patients with glioma. SEM parameters, as promising biomarkers, played an important role in histologically grading gliomas.

Methods

Biopsy specimens were grouped as high-grade glioma (HGG) or low-grade glioma (LGG). MDWI-SEM parametric mapping of DDC₁₅₀₀, α₁₅₀₀ fitted by 15 b-values (0-1,500 sec/mm²)and DDC₅₀₀₀ and α₅₀₀₀ fitted by 22 b-values (0-5,000 sec/mm²) were matched with pathological samples (stained by MIB-1 and CD34) by coregistered localized biopsies, and all SEM parameters were correlated with these pathological indices pMIB-1(percentage of MIB-1 expression positive rate) and CD34-MVD (CD34 expression positive microvascular density for each specimen). The two-tailed Spearman's correlation was calculated for pathological indexes and SEM parameters, as well as WHO grades and SEM parameters.

Results

MDWI-derived α₁₅₀₀ negatively correlated with CD34-MVD in both LGG (6 specimens) and HGG (26 specimens) (r=-0.437, P =0.012). MDWI-derived DDC₁₅₀₀ and DDC₅₀₀₀ negatively correlated with MIB-1 expression in all glioma patients (P<0.05). WHO grades negatively correlated with α₁₅₀₀(r=-0.485; P=0.005) and α₅₀₀₀(r=-0.395; P=0.025).

Conclusions

SEM-derived DDC and α are significant in histologically grading gliomas, DDC may indicate the proliferative ability, and CD34 stained microvascular perfusion may be an important determinant of water diffusion inhomogeneity α in glioma.

Outcomes and Complications of Pelvic Chondrosarcomas Treated Using Navigation Guidance and Multidisciplinary Approach: Is the Tumor Volume a Prognostic Factor?

(1) Background: Pelvic Chondrosarcomas (CS) have a poor prognosis. The grade is the most important survival predictor; other factors are periacetabular location and Dedifferentiated CS subtype. The aim of the study is to investigate a series of CS of the pelvis, to analyze the prognostic factors that affect outcomes and to demonstrate how the use of intraoperative navigation can reduce the complications without worse outcomes. (2) Methods: Retrospective study on 35 patients (21 M, 14 F), median age at surgery 54 years (IQR 41−65), with pelvic CS, treated with hemipelvectomy under navigation guidance. (3) Results: 30 high-grade CS and 5 low-grade CS; mean follow-up 51.4 months. There was a positive linear correlation between the tumor volume and the presence of local recurrence at follow-up. The mean survival time of patients with larger chondrosarcoma volume was lower, but not significantly so. Lower MSTS score was associated with significantly lower survival time (p < 0.001). (4) Conclusion: in this series overall survival, LR and distant metastasis were comparable with recent literature, while complication rate was lower compared to similar series without the use of navigation. There was a correlation between tumor volume and local recurrence rate but not with the presence of metastasis at follow up.

机器人辅助技术在创伤骨科的发展与临床应用

OBJECTIVE

To review and evaluate the basic principles and advantages of orthopedic robot-assisted technology, research progress, clinical applications, and limitations in the field of traumatic orthopedics, especially in fracture reduction robots.

METHODS

An extensive review of research literature on the principles of robot-assisted technology and fracture reduction robots was conducted to analyze the technical advantages and clinical efficacy and shortcomings, and to discuss the future development trends in this field.

RESULTS

Orthopedic surgical robots can assist orthopedists in intuitive preoperative planning, precise intraoperative control, and minimally invasive operations. It greatly expands the ability of doctors to evaluate and treat orthopedic trauma. Trauma orthopedic surgery robot has achieved a breakthrough from basic research to clinical application, and the preliminary results show that the technology can significantly improve surgical precision and reduce surgical trauma. However, there are still problems such as insufficient evaluation of effectiveness, limited means of technology realization, and narrow clinical indications that need to be solved.

CONCLUSION

Robot-assisted technology has a broad application prospect in traumatic orthopedics, but the current development is still in the initial stage. It is necessary to strengthen the cooperative medical-industrial research, the construction of doctors' communication platform, standardized training and data sharing in order to continuously promote the development of robot-assisted technology in traumatic orthopedics and better play its clinical application value.

Primary Orbital Reconstruction with Selective Laser Melting (SLM) of Patient-Specific Implants (PSIs): An Overview of 96 Surgically Treated Patients

Contemporary advances in technology have allowed the transfer of knowledge from industrial laser melting systems to surgery; such an approach could increase the degree of accuracy in orbital restoration. The aim of this study was to examine the accuracy of selective laser melted PSIs (patient-specific implants) and navigation in primary orbital reconstruction. Ninety-six patients with orbital fractures were included in this study. Planned vs. achieved orbital volumes (a) and angles (b) were compared to the unaffected side (n = 96). The analysis included the overlay of post-treatment on planned images (iPlan 3.0.5, Brainlab®, Feldkirchen, Germany). The mean difference in orbital volume between the digitally planned orbit and the postoperative orbit was 29.16 cm3 (SD 3.54, presurgical) to 28.33 cm3 (SD 3.64, postsurgical, t = 5.00, df = 95.00; p < 0.001), resulting in a mean volume difference (planned vs. postop) of less than 1 cm3. A 3D analysis of the color mapping showed minor deviations compared to the mirrored unaffected side. The results suggested that primary reconstruction in complex orbital wall fractures can be routinely achieved with a high degree of accuracy by using selective laser melted orbital PSIs.

Single-Position Fluoroscopy-Guided Lateral Lumbar Interbody Fusion With Intraoperative Computed Tomography-Navigated Posterior Pedicle Screw Fixation: Technical Report and Literature Review

Lateral lumbar interbody fusion (LLIF) is a powerful tool in minimally invasive spine surgery with high rates of fusion, excellent indirect decompression, and deformity correction. LLIF offers advantages compared with anterior lumbar interbody fusion including a more favorable complication profile. Traditionally, the interbody fusion is performed in the lateral position and fluoroscopy-assisted pedicle screw fixation performed with the patient repositioned prone. The evolution of both pedicle screw technology and intraoperative navigation has enhanced the feasibility of single (lateral)-position surgery. Early reports using fluoroscopy-assisted pedicle screws and computer or robotic navigation suggest this technique can be performed safely and accurately. The purpose of this brief report is to provide the technical steps, workflow, as well as pearls and pitfalls for single-position LLIF with true intraoperative computed tomography navigation-guided percutaneous pedicle screw fixation. A case example is included for illustration.

Surface Navigation and the Influence of Navigation on MIS Surgery

STUDY DESIGN

Literature review.

OBJECTIVES

To review the evidence for surface-based navigation in minimally-invasive spine surgery (MIS), provide an outline for its workflow, and present a wide range of MIS case examples in which surface-based navigation may be advantageous.

METHODS

A comprehensive review of the literature and compilation of findings related to surface-based navigation in MIS was performed. Workflow and case examples utilizing surface-based navigation were described.

RESULTS

The nascent literature regarding surface-based intraoperative navigation (ION) in spine surgery is encouraging and initial studies have shown that surface-based navigation can allow for accurate pedicle screw placement and decreased operative time, fluoroscopy time, and radiation exposure when compared to traditional fluoroscopic imaging. Surface-based navigation may be particularly useful in MIS cervical and lumbar decompressions and MIS lumbar instrumentation cases.

CONCLUSIONS

Overall, it is possible that surface-based ION will become a mainstay in the armamentarium of enabling technologies utilized by minimally-invasive spine surgeons, but further studies are needed assessing its accuracy, complications, and cost-effectiveness.

The impact of misplaced percutaneous iliac dynamic reference frame pins used during navigated spine surgery: incidence and outcomes

OBJECTIVE

Image guidance requires placement of a dynamic reference frame (DRF), often either onto local spinous process or by freehand intraosseous DRF placement into the ilium via the posterior superior iliac spine (PSIS). There is a paucity of studies in the literature that describe the complications of intraosseous DRF placement. The aim of this study was to describe the radiographic location, prevalence and nature of complications, and long-term clinical outcomes of attempted DRF placement into the PSIS.

METHODS

All lumbosacral spine surgical procedures performed between August 2019 and February 2021 at a single institution were queried, and operations in which a DRF was targeted to the PSIS were included. Patient demographic characteristics, indications for surgery, surgical outcomes, and complications were extracted. Intraoperative CT scans were reviewed by 2 independent researchers to determine the accuracy of DRF placement into the PSIS and to assess for DRF malposition.

RESULTS

Of 497 lumbar spine operations performed between August 2019 and February 2021 by 4 surgeons, 85 utilized intraoperative navigation with a PSIS pin. Thirteen operations were excluded due to an inability to visualize the entirety of the pin on intraoperative CT. Of 72 DRFs evaluated, 77.8% had been correctly placed in the PSIS. Of the 22.2% of DRFs not placed into the PSIS, 11 entered the sacrum, 6 crossed the sacroiliac joint, and 2 were deep enough to enter the pelvis. Pain at the pin site was present in 4 patients, of whom 3 had resolution of pain at the last follow-up evaluation. There were no significant complications due to DRF placement: no sacral fractures, significant navigation errors, retroperitoneal hematomas, or neurological deficits. Over a mean ± SD follow-up period of 9 ± 5.2 months, there were no incidences of pin site infection. Interrater reliability between the reviewers was 95.8%.

CONCLUSIONS

This was the first study to examine radiological and clinical outcomes after DRF placement in the PSIS. In this study, a majority of pins were correctly placed within the PSIS, although 22.2% of pins were malpositioned. There were no serious complications, and a majority of those patients with persistent pin site pain had resolution at last follow-up.

Analysis of Factors Affecting 5-ALA Fluorescence Intensity in Visualizing Glial Tumor Cells-Literature Review

Glial tumors are one of the most common lesions of the central nervous system. Despite the implementation of appropriate treatment, the prognosis is not successful. As shown in the literature, maximal tumor resection is a key element in improving therapeutic outcome. One of the methods to achieve it is the use of fluorescent intraoperative navigation with 5-aminolevulinic acid. Unfortunately, often the level of fluorescence emitted is not satisfactory, resulting in difficulties in the course of surgery. This article summarizes currently available knowledge regarding differences in the level of emitted fluorescence. It may depend on both the histological type and the genetic profile of the tumor, which is reflected in the activity and expression of enzymes involved in the intracellular metabolism of fluorescent dyes, such as PBGD, FECH, UROS, and ALAS. The transport of 5-aminolevulinic acid and its metabolites across the blood–brain barrier and cell membranes mediated by transporters, such as ABCB6 and ABCG2, is also important. Accompanying therapies, such as antiepileptic drugs or steroids, also have an impact on light emission by tumor cells. Accurate determination of the factors influencing the fluorescence of 5-aminolevulinic acid-treated cells may contribute to the improvement of fluorescence navigation in patients with highly malignant gliomas.

Augmented Reality and Intraoperative Navigation in Sinonasal Malignancies: A Preclinical Study

Objective

To report the first use of a novel projected augmented reality (AR) system in open sinonasal tumor resections in preclinical models and to compare the AR approach with an advanced intraoperative navigation (IN) system.

Methods

Four tumor models were created. Five head and neck surgeons participated in the study performing virtual osteotomies. Unguided, AR, IN, and AR + IN simulations were performed. Statistical comparisons between approaches were obtained. Intratumoral cut rate was the main outcome. The groups were also compared in terms of percentage of intratumoral, close, adequate, and excessive distances from the tumor. Information on a wearable gaze tracker headset and NASA Task Load Index questionnaire results were analyzed as well.

Results

A total of 335 cuts were simulated. Intratumoral cuts were observed in 20.7%, 9.4%, 1.2,% and 0% of the unguided, AR, IN, and AR + IN simulations, respectively (p < 0.0001). The AR was superior than the unguided approach in univariate and multivariate models. The percentage of time looking at the screen during the procedures was 55.5% for the unguided approaches and 0%, 78.5%, and 61.8% in AR, IN, and AR + IN, respectively (p < 0.001). The combined approach significantly reduced the screen time compared with the IN procedure alone.

Conclusion

We reported the use of a novel AR system for oncological resections in open sinonasal approaches, with improved margin delineation compared with unguided techniques. AR improved the gaze-toggling drawback of IN. Further refinements of the AR system are needed before translating our experience to clinical practice.

Classification of Pituitary Adenomas Invading the Cavernous Sinus Assisted by Three-Dimensional Multimodal Imaging and Its Clinical Application

Introduction  To help diagnose and evaluate the prognosis of pituitary adenoma with cavernous sinus (CS) invasion and guide endonasal endoscopic surgery (EES) assisted by intraoperative navigation (ION) with three-dimensional multimodal imaging (3D-MMI). We propose a classification of CS invasion based on 3D-MMI. Methods  We picked some appropriate cases and reconstructed the 3D-MMI and then classified them into 3 grades according to the stereo relationship among ICA, tumor and CS in 3D-MMI. Then, we applied different strategies according to their grade to remove pituitary adenomas that invaded the CS. Results  All 38 patients were divided into 3 grades. Tumors compressing the ICA and CS without CS invasion were divided into grade 1. Tumors encasing the ICA and invading the superior-posterior compartment and/or anterior-inferior compartment but without distinct separation of the ICA and CS lateral wall were deemed as grade 2. Tumors encasing the ICA and filling the lateral compartment of the CS that dissociated the lateral wall from the ICA were deemed as grade 3. The 3D-MMI enabled adequate spatial visualization of the ICA, CS and tumors. All patients were operated on under the guidance of ION with 3D-MMI. Conclusion  Classification based on 3D-MMI can better demonstrate the relationships among tumor, ICA and CS in a stereo and multi-angle view, which will have significance in guiding the surgical strategy.

Can Postoperative CT Imaging in Spine Surgery Be Replaced by Intraoperative 3D Rotation With the C-Arm?: Results of a Prospective Single Center Cohort Study

Objective: Dorsal instrumentation of the spine is an established treatment option for a range of spinal pathologies. Intraoperative fluoroscopy connected with navigation minimize the risk of incorrect screws placement. In several cases, post-operative CT scans are needed to verify possible mismatches. In this study, we evaluated the efficacy of 3D intraoperative fluoroscopy as compared to post-operative CT and the need of post-operative CT.

Methods: We conducted a prospective single-center cohort study, 94 patients were included. The screws were implanted using 3D rotation with C-arm and navigation system. The definitive position of the screws was verified by a post-operative CT scan. Finally, we compared the discrepance between intraoperative imaging and post-operative CT scan using Rampersaud-grade (A-D).

Results: 607 screws in 94 patients were included. Some 3% of the screws had to be replaced immediately intraoperative due to inadequate position with lateral or medial trajectory. An A-score was achieved for 85.5% of the 3D controlled screws and 87% of the post-operative CT. A B-score was found in 11.5% of either groups. In the 3D group a C-score was achieved for 2.5% and in the CT group for 0.8%. A D-score was found in 0.5% of the screws in both groups, p = 0.45. Only a mismatch of 3% could be detected for the intraoperative and post-operative imaging results.

Conclusion: Our study data shows that the placement of screws using the 3D rotation and navigation tool is safe and accurate. There were no relevant mismatches between intraoperative images and the post-operative CT.

Maxillectomy Reconstruction Revision Using Virtual Surgical Planning and Intraoperative Navigation

Secondary revision of osseous flap reconstructions of the maxilla can enhance facial symmetry, but can be challenging due to the absence of normal anatomy and landmarks. We report four cases of maxillectomy reconstruction with scapula tip flap employing a novel combined approach with preoperative virtual surgical planning (VSP) and intraoperative navigation (ION) for secondary revision. VSP was employed to superimpose mirrored normal anatomy upon the reconstructed anatomy, and ION used for real-time intraoperative anatomical mapping. VSP and ION can be used to optimize maxillary bony revisions and recontouring, thereby improving anatomic symmetry and funtionality. Laryngoscope, 2021.

Preoperative planning for intraoperative navigation guidance

Intraoperative navigation for spinal procedures has continued to gain popularity. Numerous platforms are currently on the market and offer a spectrum of features. Preoperative considerations when utilizing this technology begin with understanding the fundamental concepts and methods of navigation. Several key factors including patient positioning, reference array placement, and sequence of instrumentation can help improve intraoperative navigation workflow when planned appropriately. The authors review current literature to help guide surgeon decision making when utilizing navigation. Additionally, tips and techniques for use of navigation are detailed to help avoid common surgeon pitfalls. In general, navigation platforms are classified based on image acquisition and degree of surgeon motion restriction during instrumentation. Imageless platforms often require preoperative images to be uploaded into the navigation system. Image-based systems rely on intraoperative imaging to ensure accuracy of its referencing software. The system then creates a three-dimensional model that allows for visualization of the navigated instrument within the surgical field. Active and passive navigation describe the degree of surgeon free-motion restriction when utilizing navigated instruments. Active navigation platforms, such as most robotic systems, prevent the deviation of the surgeon's instrument from a predetermined trajectory. Passive navigation does not restrict surgeon motion and the projected trajectory of the instrumented can be displayed on a three-dimensional model.

Impact of preoperative 3-dimensional planning and intraoperative navigation of shoulder arthroplasty on implant selection and operative time: a single surgeon's experience

BACKGROUND

Preoperative 3D planning and intraoperative navigation for shoulder arthroplasty has recently gained interest because of the potential to enhance the surgeon's understanding of glenoid anatomy and improve the accuracy of glenoid component positioning. The purpose of our study was to assess the impact of preoperative 3D planning on the surgeon's selection of the glenoid component (standard vs. augmented) and compare duration of surgery with and without intraoperative navigation.

METHODS

We retrospectively analyzed 200 consecutive patients who underwent shoulder arthroplasty. The first group of 100 patients underwent shoulder arthroplasty using standard 2D preoperative planning based on standard radiographs and computed tomographic scans. The second group of 100 patients underwent shoulder arthroplasty using 3D preoperative planning and intraoperative navigation. Type of glenoid component and operative time were recorded in each case.

RESULTS

For the group of patients with standard preoperative planning, only 15 augmented glenoid components were used, whereas in the group of patients with 3D preoperative planning and navigation, 54 augments were used (P < .001). The operative time was 11 minutes longer for the procedures that used intraoperative navigation, compared with those that did not (P < .001). This difference diminished as the surgeon became more proficient with the navigation technique.

CONCLUSION

Use of preoperative 3D planning changes the surgeon's understanding of the patient's glenoid anatomy. In our study, using 3D planning increased the likelihood that the surgeon selected an augmented glenoid component compared with 2D planning. Intraoperative navigation slightly lengthened the duration of surgery, but this became insignificant as part of a learning curve within 6 months.

Contrast-Enhanced Multispectral Photoacoustic Imaging for Irregular Hepatectomy Navigation: A Pilot Study

Irregular hepatectomy plays a prominent role in the treatment of small hepatocellular carcinoma (HCC) patients with severe cirrhosis and localized liver metastasis. In clinical practices, intraoperative tumor boundaries delineation facilitates to accomplish tumor resection with negative margin, remarkably decreasing the recurrence rates. Currently, ultrasound (US) and ICG fluorescence-guided surgery has been used for intraoperative navigation in irregular hepatectomy, but insufficient specificity results in a limited prevalence. Inspired by the high resolution of photoacoustic (PA) imaging and established clinical efficacy of ¹⁸F-Alfatide that is specific for integrin α_vβ₃-overexpressed tumors, we herein developed a fluorescent analogue IR820-E[c(RGDfK)]₂, and a proof-of-concept intraoperative multispectral PA imaging navigation for precise irregular hepatectomy using hand-held PA/US imaging system. An integrin α_vβ₃-targeted fluorescent contrast agent IR820-E[c(RGDfK)]₂ was designed, synthesized, and characterized. In vitro studies were performed to determine optical and PA properties, affinity and specificity and biocompatibility. Multispectral PA imaging, the optimal imaging time point and contrast, multispectral PA imaging-guided irregular hepatectomy, pharmacokinetics, and safety profile were evaluated in subcutaneous and orthotopic HCC tumor models. Ex vivo macroscopic three-dimensions (3D) PA imaging with IR820-E[c(RGDfK)]₂ staining was also performed in surgical biospecimens from patients with HCC. IR820-E[c(RGDfK)]₂ has a simple synthetic method at gram scale, high affinity, and specificity for integrin α_vβ₃, excellent pharmacokinetic and safety profile can effectively differentiate tumor from normal liver tissues in animal models and surgical biospecimens from HCC patients. Preoperative tumor localization, intraoperative tumor boundaries delineation, and tumor excision, and postoperative negative margin assessment were successfully achieved during irregular hepatectomy. This initial attempt allows one to preoperatively detect tumor lesions, intraoperatively delineate tumor boundaries and guide tumor resection, and postoperatively evaluate tumor margin status during irregular hepatectomy. IR820-E[c(RGDfK)]₂ has the potential to be an investigational new drug for clinical use in multispectral photoacoustic imaging-guided irregular hepatectomy.

Compared with conventional procedures, an intraoperative navigation system for ventriculoperitoneal shunting via the occipital horn improves outcomes in patients with hydrocephalus

BACKGROUND

Ventriculoperitoneal shunting (VPS) is a common neurosurgical procedure used to treat hydrocephalus. Although the use of a navigation system in VPS achieves superior results compared with conventional surgery, the relationships among clinical symptoms, ventricular catheter placement, catheter obstruction, and the postoperative Evans index have not been clearly reported.

METHODS

We performed a retrospective study of 40 patients with VPS (the navigation surgery group) and 31 patients with VPS (the conventional surgery group). Clinical data, follow-up times, catheterization accuracy, postoperative outcomes, cumulative survival times, and correlations between catheter placement and obstruction, symptom grade and the postoperative Evans index were analyzed.

RESULTS

Thirty-seven patients experienced optimal ventricular catheter placement (grade 1), three experienced suboptimal placements (grade 2), and none experienced poor ventricular catheter placement (grade 3) in the navigation surgery group. Greater improvement in postoperative symptoms (p < 0.001), including less catheter readjustment (p < 0.001), was observed in the navigation surgery group. A Kaplan-Meier analysis showed that the cumulative catheter obstruction-free survival time was longer in the navigation surgery group (p = 0.016). Moreover, catheter placement was significantly correlated with catheter obstruction (p < 0.001). Additionally, catheter obstruction was significantly correlated with the symptom grade (p < 0.001) and postoperative Evans index (p = 0.002).

CONCLUSION

VPS for hydrocephalus via the occipital horn with a navigation system is superior to the conventional surgical procedure in terms of clinical outcomes, the precision of ventricular catheterization, and the occurrence of complications. Catheter obstruction-free survival times were longer in the navigation surgery group and catheter placement was significantly correlated with catheter obstruction.

A review of computer-assisted orthopaedic surgery systems

BACKGROUND

Computer-assisted orthopaedic surgery systems have great potential, but no review has focused on computer-assisted surgery systems for the spine, hip, and knee.

METHODS

A systematic search was performed in Web of Science and PubMed. We searched the literature on computer-assisted orthopaedic surgery systems from 2008 to the present and focused on three aspects of systems: training, planning, and intraoperative navigation.

RESULTS AND DISCUSSION

In this review study, we reviewed 34 surgical training systems, 31 surgical planning systems, and 41 surgical navigation systems. The functions and characteristics of the surgical systems were compared and analysed, and the current concerns about and the impact of the surgical systems on doctors and surgery were clarified.

CONCLUSION

Computer-assisted orthopaedic surgery systems are still in the development stage. Future surgical training systems should include synthetic models with patient anatomy. Surgical planning systems with automatic planning should be developed, and surgical navigation systems with multimodal fusion, robotic assistance and imaging should be developed.

[Assessment of the safety and accuracy of implantation of screws into the C2 vertebra using individual 3D-navigation matrices]

Introduction

Individual 3D-navigation matrices are valuable to increase the safety of screw implantation into the axis.

Objective

To analyze safety and accuracy of screw deployment into the axis using individual 3D-navigation matrices compared to free hand technique.

Material and methods

A retrospective analysis included 23 patients (group 1) who underwent implantation of 44 screws into the axis using the «free hand» technique. The screws were installed along the transpedicular or pars trajectory. A prospective analysis enrolled 17 patients (group 2) who underwent installation of 34 screws using individual navigation matrices. 3D-printing technology was applied for manufacturing these matrices. Implantation results were evaluated considering postoperative CT data and SGT (Screw Guide Template) system.

Results

In the 1st group («free hand»), grade 0 and 1 (no malposition or less than 50% of screw diameter) were recorded for 29 (65.91%) screws, grade 2 - for 13 (29.55%) screws, grade 3 - for 2 (4.45%) screws. Intraoperative injury of the vertebral artery without postoperative neurological deficit occurred in 4 (8.89%) patients. In the 2nd group, 97% of screws were implanted in accordance with grades 1 and 2. Deviation grade 2 was registered in 11 cases (32.35%). Mean deviation was 1.8 ± 1.0 mm. In the 2nd group, 28 (82.35%) out of 34 screws were completely within the bone structures (grade 0), 4 (11.76%) screws perforated pedicles for less than 50% of their diameter (grade 1). There were 2 cases of malposition grade 2 and 3 without vertebral artery injury.

Conclusion

Individual 3D navigation matrix is an effective method for screw installation into the axis. This approach exceeds fluoroscopy-assisted "free hand" technique in terms of safety of implantation.

Intraoperative Navigation and Cone Beam Computed Tomography for Restoring Orbital Dimensions: A Single-Center Experience

Background

Correction of post-traumatic orbital defects remains a challenge for the maxillofacial surgeon. We examined the added value of combined intraoperative (IO) navigation and IO cone beam computed tomography (CBCT).

Materials and Methods

A retrospective cohort study was performed in all consecutive patients requiring unilateral post-traumatic orbital surgery between January 2012 and December 2018. Patients were divided into 3 groups: IO navigation (NAV), IO-CBCT (CBCT), and IO navigation with IO-CBCT (NAV-CBCT). A detailed description of our workflow is provided. Volumetric comparison of the operated orbit to the contralateral orbit was made with Brainlab.

Results

Of the 81 cases, 22 patients were included (12 males/10 females) with a mean age of 51 years. Three patients were assigned to NAV, 6 to CBCT, and 13 to NAV-CBCT. The reconstructed orbital volume did not significantly differ from the contralateral orbital volume within the 3 groups. The mean difference between the contralateral and the operated orbit was 3.05 cm³, 3.72 cm³, and 1.47 cm³ for NAV, CBCT, and NAV-CBCT, respectively, where only NAV-CBCT showed a significant smaller volumetric difference in comparison to CBCT alone. Gender or age did not correlate with difference in orbital volume. Normal function and aesthetics was seen at 6 weeks postoperative in 0 of 3, 6of 6, and 6 of 13 patients of the NAV, CBCT, and NAV-CBCT, respectively.

Conclusion

Orbital defects can be treated effectively using IO navigation. Although our data could not demonstrate a significant added value of IO-CBCT in cases where IO navigation was used based on volumetric difference alone, the combination of IO-CBCT and IO navigation seems to give the best results considering both volumetric difference and postoperative function and aesthetics. Confirmation in a prospective, randomized trial with a larger sample size is required.

Label-Free Visualization of Early Cancer Hepatic Micrometastasis and Intraoperative Image-Guided Surgery by Photoacoustic Imaging

The detection of cancer micrometastasis for early diagnosis and treatment poses a great challenge for conventional imaging techniques. The aim of our study was to evaluate the performance of photoacoustic imaging (PAI) in detecting hepatic micrometastases from melanoma at a very early stage and in aiding tumor resection by intraoperative guidance. Methods: In vivo studies were performed by following protocols approved by the Ethical Committee for Animal Research at Xiamen University. First, a mouse model of B16 melanoma metastatic to the liver (n = 10) was established to study the development of micrometastases in vivo. Next, the mice were imaged by a scalable PAI instrument, ultrasound, 9.4-T high-resolution MRI, PET/CT, and bioluminescence imaging. PAI scans acquired with optical wavelengths of 680-850 nm were kept spectrally unmixed by using a linear least-squares method to differentiate various components. Differences in signal-to-background ratios among different modalities were determined with the 2-tailed paired t test. The diagnostic results were assessed with histologic examination. Excised liver samples from patients diagnosed with hepatic cancer were also examined to identify the tumor boundaries. Surgical removal of metastatic melanoma was precisely guided in vivo by the portable PAI system. Results: PAI was able to detect metastases as small as approximately 400 μm at a depth of up to 7 mm in vivo-a size that is smaller than can be detected with ultrasound and MRI. The tumor-to-liver ratio for PAI at 8 d (4.2 ± 0.2, n = 6) and 14 d (9.2 ± 0.4, n = 5) was significantly higher than for PET/CT (1.8 ± 0.1, n = 5, and 4.5 ± 0.2, n = 5, respectively; P < 0.001 for both). Functional PAI revealed dynamic oxygen saturation changes during tumor growth. The limit of detection was approximately 219 cells/μL in vitro. We successfully performed intraoperative PAI-guided surgery in vivo using the portable PAI system. Conclusion: Our findings offer a rapid and effective complementary clinical imaging application to noninvasively detect micrometastases and guide intraoperative resection.

Application of an open position splint integrated with a reference frame and registration markers for mandibular navigation surgery

Navigation surgery plays an important role in modern craniomaxillofacial surgery, but it is difficult to apply navigation surgery to the mandible, due to its mobility. At present, headbands or headpins are widely used for fixation of the reference frame, and three strategies are generally used for the application of navigation surgery to the mandible. This article reports the application of a novel open position splint integrated with a reference frame and registration markers for mandibular navigation surgery as a fourth strategy. Using this custom-made integrated splint, a marker-based pair-point registration procedure was completed easily and non-invasively. Furthermore, the neurovascular canal tract could be easily identified, and the cyst, as well as the surrounding daughter cysts, could be removed with high accuracy. This strategy has potential for widespread clinical application in mandibular navigation surgery.

Implant-oriented navigation in orbital reconstruction part II: preclinical cadaver study

In orbital reconstruction, the acquired position of an orbital implant can be evaluated with the aid of intraoperative navigation. Feedback of the navigation system is only obtained after positioning of the implant: the implant's position is not tracked in real time during positioning. The surgeon has to interpret the navigation feedback and translate it to desired adjustments of the implant's position. In a previous study, a real-time implant-oriented navigation approach was introduced and the system's accuracy was evaluated. In this study, this real-time navigation approach was compared to a marker-based navigation approach in a preclinical set-up. Ten cadavers (20 orbital defects) were reconstructed twice, by two surgeons (total: 80 reconstructions). Implant positioning was significantly improved in the real-time implant-oriented approach in terms of roll (2.0° vs. 3.2°, P=0.03), yaw (2.2° vs. 3.4°, P=0.01) and translation (1.3mm vs. 1.8mm, P=0.005). Duration of the real-time navigation procedure was reduced (median 4.5 min vs. 7.5 min). Subjective appreciation of the navigation technique was higher for real-time implant-oriented navigation (mean 7.5 vs. 9.0). Real-time implant-oriented navigation feedback provides real-time, intuitive feedback to the surgeon, which leads to improved implant positioning and shortens duration of the navigation procedure.

Combination of Low-Temperature Electrosurgical Unit and Extractive Electrospray Ionization Mass Spectrometry for Molecular Profiling and Classification of Tissues

Real-time molecular navigation of tissue surgeries is an important goal at present. Combination of electrosurgical units and mass spectrometry (MS) to perform accurate molecular visualization of biological tissues has been pursued by many research groups. Determination of molecular tissue composition at a particular location by surgical smoke analysis is now of increasing interest for clinical use. However, molecular analysis of surgical smoke is commonly lacking molecular specificity and is associated with significant carbonization and chemical contamination, which are mainly related to the high temperature of smoke at which many molecules become unstable. Unlike traditional electrosurgical tools, low-temperature electrosurgical units allow tissue dissection without substantial heating. Here, we show that low-temperature electrosurgical units can be used for desorption of molecules from biological tissues without thermal degradation. The use of extractive electrospray ionization technique for the ionization of desorbed molecules allowed us to obtain mass spectra of healthy and pathological tissues with high degree of differentiation. Overall, the data indicate that the described approach has potential for intraoperative use.

Intraoperative Error Propagation in 3-Dimensional Spinal Navigation From Nonsegmental Registration: A Prospective Cadaveric and Clinical Study

STUDY DESIGN

Prospective pre-clinical and clinical cohort study.

OBJECTIVES

Current spinal navigation systems rely on a dynamic reference frame (DRF) for image-to-patient registration and tool tracking. Working distant to a DRF may generate inaccuracy. Here we quantitate predictors of navigation error as a function of distance from the registered vertebral level, and from intersegmental mobility due to surgical manipulation and patient respiration.

METHODS

Navigation errors from working distant to the registered level, and from surgical manipulation, were quantified in 4 human cadavers. The 3-dimensional (3D) position of a tracked tool tip at 0 to 5 levels from the DRF, and during targeting of pedicle screw tracts, was captured in real-time by an optical navigation system. Respiration-induced vertebral motion was quantified from 10 clinical cases of open posterior instrumentation. The 3D position of a custom spinous-process clamp was tracked over 12 respiratory cycles.

RESULTS

An increase in mean 3D navigation error of ≥2 mm was observed at ≥2 levels from the DRF in the cervical and lumbar spine. Mean ± SD displacement due to surgical manipulation was 1.55 ± 1.13 mm in 3D across all levels, ≥2 mm in 17.4%, 19.2%, and 38.5% of levels in the cervical, thoracic, and lumbar spine, respectively. Mean ± SD respiration-induced 3D motion was 1.96 ± 1.32 mm, greatest in the lower thoracic spine (P < .001). Tidal volume and positive end-expiratory pressure correlated positively with increased vertebral displacement.

CONCLUSIONS

Vertebral motion is unaccounted for during image-guided surgery when performed at levels distant from the DRF. Navigating instrumentation within 2 levels of the DRF likely minimizes the risk of navigation error.

Revising Substantial Leg Length Discrepancy in Total Hip Arthroplasty Using Computer-assisted Navigated Systems: A Case Series of Three Patients

One of the primary challenges of total hip arthroplasty (THA) is equalizing the limb lengths to re-establishing normal hip biomechanics. Post-operative leg length discrepancies (LLD) lead to patient dissatisfaction and are a main source of orthopedic malpractice cases. The aim of this case series was to document three cases of substantial LLD that were corrected during THA with the assistance of an imageless computer navigation system. Medical records were reviewed for history and radiographs were consulted. All patients in this series presented with complaints related to hip fractures and reported a significant lengthening of leg length following THA. No surgical complications of adverse events were reported. In these cases, imageless navigation provided intraoperative measurements of leg length which allowed for enhanced accuracy of component placement and improved outcomes following surgery.

Supporting fibula free flap harvest with augmented reality: A proof-of-concept study

OBJECTIVE

To analyze a novel navigation system utilizing augmented reality (AR) as a supporting method for fibula free flap (FFF) harvest and fabrication.

METHODS

A total of 126 simulated osteotomies supported with a cutting guide or one of two AR-based intraoperative navigation modules-simple AR (sAR) or navigated AR (nAR)-were carried out on 18 identical models of the fibula (42 osteotomies per method). After fusing postoperative computed tomography scans of the operated fibulas with the virtual surgical plan based on preoperative images, the objective outcomes-angular deviations from the planned osteotomy trajectory (^o ) and deviations of control points marked on the trajectory (mm)-were determined.

RESULTS

All analyzed methods provided similar accuracy of assisted osteotomies. The only significant difference referred to angular deviation in the sagittal plane, which was smaller after the cutting guide-assisted procedures than after the application of sAR and nAR (4.1 ± 2.29 vs. 5.08 ± 3.64 degrees, P = 0.031 and 4.1 ± 2.29 vs. 4.97 ± 2.91, P = 0.002, respectively). Mean deviation of control points after the cutting guide-assisted procedures was 2.76 ± 1.06 mm, as compared with 2.67 ± 1.09 mm for sAR and 2.95 ± 1.11 mm for nAR.

CONCLUSION

Our study demonstrated that both novel AR-based methods provided similar accuracy of assisted harvesting and contouring of the FFF as the cutting guides. This fact, as well as the acceptability of the concept by clinicians, justify their further development and evaluation in preclinical settings.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:1173-1179, 2020.

Is intraoperative navigation for needle breakage mandatory?: A case report

BACKGROUND AND OVERVIEW

Needle breakage when administering local anesthetic in the oral cavity can be of major concern to both the patient and the dentist. Intraoperative navigation has become the most popular advanced imaging technique.

CASE DESCRIPTION

In this report, the authors describe a case of needle breakage during inferior alveolar nerve block for a dental procedure. Using preoperative imaging, the authors located the needle and removed it while the patient was under general anesthesia. The authors review studies and case reports similar to the pre- and intraoperative imaging modalities presented in their report.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Preoperative 3-dimensional imaging is sufficient for establishing the exact location of the broken needle, especially in cases in which potential migration is unlikely.

[Virtual surgical planning and intraoperative navigation for mandibular reconstruction: from accurate to minimal invasive]

Simultaneous restoration of function and appearance should be performed in mandibular reconstruction. Option of reconstructive techniques is determined by cause, location, extent, and classification of the mandibular defects. Vascularize bone graft is one of the most popular technique in current clinical practice of mandibular reconstruction. Fibula is the most common donor site for mandibular reconstruction. The disadvantage of low height of neo-mandible reconstructed by single fibular segment can be solved by vascularized double barrel fibula graft. Using virtual surgical planning and intraoperative navigation for mandibular reconstruction leads to simplify surgical procedure, reduce operating time and injury, and decrease donor site morbidity so that accurate mandibular reconstruction could be completed. Direction of minimal invasive surgery for mandibular reconstruction will be developed by intraoral approach and intraoral anastomosis.

Preservation of the Acetabular Cup During Revision Total Hip Arthroplasty Using a Novel Mini-navigation Tool: A Case Report

Introduction:

While intraoperative navigation systems have been shown to improve outcomes in primary total hip arthroplasty (THA), their use in the context of revision has been largely overlooked. This case report presents the first documented use of an imageless navigation tool in the context of revision THA, and an unexpected benefit to the surgical procedure as a result.

Case Report:

An 84-year-old female patient presented following five episodes of dislocation of the left hip and with pain in the left buttock, groin, and posterior aspect of her hip. Relevant surgical history included primary hip arthroplasty in 1999 and the first revision in 2014. Preoperative analysis revealed a constrained liner that had become disengaged and migrated inferiorly, lodging at the distal aspect of the femoral neck. Acetabular protrusion was also noted. The pre-operative plan included the replacement of the fragmented liner and likely of the acetabular cup due to hardware failure. Intraoperative assessment, however, revealed that the cup was in good condition and would be difficult to remove due to substantial bony ingrowth. With the assistance of imageless navigation, the orientation of the acetabular cup was determined and a new constrained liner was cemented into the preexisting acetabular component at an altered orientation, correcting anteversion by 7°.

Conclusions:

In revision hip arthroplasty cases, image-based navigation is limited by the presence of existing implants and corresponding metal artefact. This case demonstrates the successful use of an imageless navigation tool for revision surgery. Use of navigation led to the unexpected intraoperative discovery that the acetabular cup was in an acceptable state, and allowed the surgical team to correct the position of the cup using a constrained liner, thus preserving the cup. This significantly benefitted patient outcome, due to the risks associated with the removal of a firmly fixated acetabular cup. While more extensive research is required, this case demonstrates that imageless navigation may be an indispensable tool for revision surgery.

Computer-aided planning with exact implementation into surgical technique in TKA is as accurate as intraoperative navigation

BACKGROUND

Exact positioning of implants and accuracy of alignment are important parameters to provide an long survivorship of endoprostheses after total knee arthroplasty. It was suggested that an alignment within 3∘ from centerline provides the best long-term survivorship of TKA. Therefore, computer-assisted navigation became more important in TKAs. Another tool to improve the accuracy in TKA is the preoperative planning software.

OBJECTIVE

Main goal was to determine if advantages of an intraoperative navigation system during TKA can be reached by an exact implementation of a preoperative computer-aided planning.

METHODS

Based on all patients (n= 100) underwent primarily TKA in 2015 and 2016 two groups were declared: (1) conventionally operated TKA without navigation system and (2) operation with an optical navigation system. Data on age, sex, date, operative time, severe complications and preoperative vs. postoperative alignment were collected retrospectively.

RESULTS

The two groups do not differ in postoperative alignment and frequency of outliers. Furthermore, there was no difference referring to complications and the length of stay in hospital, but operative time was prolonged in the navigation-assisted group.

CONCLUSIONS

It can be stated that conventional surgical techniques in TKA are as accurate as navigated ones if an exact preoperative computer aided planning is implemented during surgery.

Theranostic imaging of liver cancer using targeted optical/MRI dual-modal probes

The accurate preoperative detection and intraoperative navigation afforded by imaging techniques have had significant impact on the success of liver cancer surgeries. However, it is difficult to achieve satisfactory performance in both diagnosis and surgical treatment processes using any single modality imaging method. Here, we report the synthesis and characteristics of a novel dual-modality magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) probe and verify its feasibility in nude mouse models with liver cancer. The probes are comprised of superparamagnetic iron oxide (SPIO) nanoparticles coated with liposomes to which a tumor-targeted agent, Arg-Gly-Asp peptides (RGD), and a NIRF dye (indocyanine green, ICG) have been conjugated. Specific targeting, biodistribution, and the imaging ability of the probes for MRI-NIRF were examined. Furthermore, we applied the dual-modality methodology toward the preoperative diagnosis and intraoperative guidance of radical resection in mouse models with both orthotopic liver tumors and intrahepatic tumor metastasis. The study demonstrated that both MRI and fluorescent images showed clear tumor delineation after probe injection (SPIO@Liposome-ICG-RGD). The contrast-to-noise ratio obtained from MRI was 31.9 ± 25.4 at post-injection for the preoperative diagnosis, which is helpful for detecting small tumors (0.9 ± 0.5 mm). The maximum tumor to background ratio of NIRF imaging was 2.5 ± 0.3 at 72 h post-injection for effectively capturing miniscule tumor lesions (0.6 ± 0.3 mm) intraoperatively. The novel MRI-NIRF dual modality probes are promising for the achievement of more accurate liver tumor detection and resection.

Intraoperative Computed Tomography Navigation During Thoracoscopic Segmentectomy for Small-sized Lung Tumors

Performance of thoracoscopic pulmonary segmentectomy for primary lung cancer or pulmonary metastases has recently increased. In patients with emphysema, identification of the intersegmental line is often difficult. For nonpalpable lesions, securing a sufficient surgical margin is more likely to be uncertain. The purpose of this study was to evaluate the efficacy of intraoperative computed tomography (CT) scan during video-assisted thoracoscopic surgery (VATS) pulmonary segmentectomy. This study included 12 patients who underwent intraoperative CT-assisted VATS segmentectomy between January 2015 and August 2016. After dividing the corresponding vessels and bronchi, the intersegmental line was marked by clipping, and intraoperative CT scan was performed under bilateral lung ventilation. The intraoperative CT or 3-dimensional CT reconstruction images were used by the surgeons to confirm the correct anatomical segmental border and to secure a sufficient resection margin. In all patients, the location of the lesions to be resected, the intersegmental border, and the surgical margins could be confirmed while performing VATS segmentectomy. Complete resection was achieved in all patients. Although the pathologic margins tended to be shorter than the surgical margins on intraoperative CT images, there was a strong correlation between these 2 variables (r = 0.963, P < 0.0001). Intraoperative CT scan during VATS segmentectomy was useful for identifying the location of nonpalpable lesions, confirming anatomical intersegmental borders and securing the resection margins. Intraoperative CT navigation could enable a more definitive VATS segmentectomy for nonpalpable lesions.

Direct Anterior Approach Using Navigation Improves Accuracy of Cup Position Compared to Conventional Posterior Approach

The accuracy of cup position in total hip arthroplasty is essential for a satisfactory result as malpositioning increases the risk of complications including dislocation, high wear rate, loosening, squeaking, edge loading, impingement and ultimately failure.

We studied 166 patients in a single-surgeon-series of matched cohorts of patients who underwent total hip arthroplasties. Four separate groups were identified comprising of the posterior approach +/- navigation and the direct anterior approach +/- navigation.

We found a significant difference between the direct anterior navigated group and the posterior non-navigated group for both anteversions (P < 0.05, confidence interval (CI) -3.86 to -1.73) and inclination (P < 0.05, CI -3.08 to -1.08). Almost, 72% of anterior navigated patients fell within 5^o of the navigation software set target cup position of 45^o inclination and 20^o anteversion and 100% were within 10^o. Only 30% of posterior non-navigated were within 5^o of both anteversion and inclination and 73% were within 10^o.

There was also a significant difference between the direct anterior navigated and non-navigated group with respect to anteversion only (p < 0.05, CI 1.50 to 1.30). There were no other significant differences between approaches +/- navigation.

The direct anterior approach allows ease of access to both anterior-superior iliac spines for navigation and a supine patient allows anteversion and inclination to be measured in the frontal plane. We conclude that the direct anterior approach with navigation improves the accuracy of cup position compared to the conventional posterior approach without navigation.

The Application of Heptamethine Cyanine Dye DZ-1 and Indocyanine Green for Imaging and Targeting in Xenograft Models of Hepatocellular Carcinoma

Near infrared fluorescence (NIRF) imaging has strong potential for widespread use in noninvasive tumor imaging. Indocyanine green (ICG) is the only Food and Drug Administration (FDA) -approved NIRF dye for clinical diagnosis; however, it is unstable and poorly targets tumors. DZ-1 is a novel heptamethine cyanine NIRF dye, suitable for imaging and tumor targeting. Here, we compared the fluorescence intensity and metabolism of DZ-1 and ICG. Additionally, we assayed their specificities and abilities to target tumor cells, using cultured hepatocellular carcinoma (HCC) cell lines, a nude mouse subcutaneous xenograft model of liver cancer, and a rabbit orthotopic transplantation model. We found that DZ-1 accumulates in tumor tissue and specifically recognizes HCC in subcutaneous and orthotopic models. The NIRF intensity of DZ-1 was one order of magnitude stronger than that of ICG, and DZ-1 showed excellent intraoperative tumor targeting in the rabbit model. Importantly, ICG accumulated at tumor sites, as well as in the liver and kidney. Furthermore, DZ-1 analog-gemcitabine conjugate (NIRG) exhibited similar tumor-specific targeting and imaging properties, including inhibition of tumor growth, in HCC patient-derived xenograft (PDX) mice. DZ-1 and NIRG demonstrated superior tumor-targeting specificity, compared to ICG. We show that DZ-1 is an effective molecular probe for specific imaging, targeting, and therapy in HCC.

Application of a non-invasive reference headband and a surgical splint for intraoperative paediatric navigation

The key to the success of surgical navigation based on computer-aided design and computer-aided manufacturing (CAD/CAM) planning is the registration process. This has to be precise and adapted to the surgical needs. However, the application of a conventional rigid skull-fixed navigation star for accurate registration is limited for use in the paediatric population, because of the risk of unstable fixation, dural perforation, and intracranial bleeding. The authors describe their experience with a non-invasive reference headband that was used in combination with a custom-made acrylic resin dental registration splint for resection of a rare infraorbital zygomatic desmoplastic fibroma in a 2-year old patient. This approach appears not to have been reported in the literature to date.

S-1 and S-2-alar-iliac screw fixation via intraoperative navigation

Adult deformity patients often require fixation to the sacrum and pelvis for construct stability and improved fusion rates. Although certain sacropelvic fixation techniques can be challenging, the availability of intraoperative navigation has made many of these techniques more feasible. In this video case presentation, the authors demonstrate the techniques of S-1 bicortical screw and S-2-alar-iliac screw fixation under intraoperative navigation in a 67-year-old female. This instrumentation placement was part of an overall T-10-pelvis construct for the correction of adult spinal deformity. The video can be found here: https://youtu.be/3HZo-80jQr8 .

Application of surgical navigation in styloidectomy for treating Eagle's syndrome

PURPOSE

The present study aimed to evaluate the feasibility, accuracy, and clinical effect of intraoperative navigation for resection of elongated styloid process (ESP) in Eagle's syndrome.

PATIENTS AND METHODS

Twelve patients with Eagle's syndrome with clinically and radiologically established diagnoses of ESP were included in this study. Preoperatively, all patients accepted three-dimensional computed tomography scan, and their skulls' digital imaging and communications in medicine data were inputed into the navigation system workstation to make a virtual surgical plan in advance. During surgery, the intraoperative navigation was performed to excise the ESP accurately for both intraoral (without tonsillectomy) and extraoral approaches following the virtual plan. Postoperatively, the amount of bleeding, duration of operation and hospitalization, and the length of resected styloid process (SP) were measured and compared with those cases that had traditional styloidectomy without the help of surgical navigation (SN). A simple visual analog scale questionnaire was also used to assess patients' satisfaction and the surgery effect after 3 months.

RESULTS

In total, 17 SPs from 12 patients were precisely resected by intraoral parapharyngeal approach and small cervical approach with the aid of SN. No severe complications occurred in any patients. The length of resected SPs was 21.93±14.26 mm. The average amount of bleeding and duration of operation were 22.50±8.54 mL and 40.35±11.81 minutes, respectively, which were all less than with traditional styloidectomy. The visual analog scale analysis showed that the discomfort in all patients was relieved, while ten patients' symptoms were improved greatly, and two patients had some improvement.

CONCLUSION

The higher accuracy of surgery, lesser amount of bleeding, decreased duration of surgery and hospitalization, absence of complications, and improved subjective symptoms indicated that SN is an effective and minimally invasive surgical procedure suitable for resection of ESP for treating Eagle's syndrome.

Redirecting pedicle screws: a revision spinal fusion strategy using three-dimensional image guidance

BACKGROUND

Pedicle screws are a preferred method for spinal fixation because of their three-column support and rigid posterior stabilization. The purpose of this study was to evaluate the outcome of patients requiring pedicle screw redirection, and to describe a technique using cone-beam computed tomography (cbCT).

METHODS

A retrospective review of 30 patients undergoing revision spinal fusion with redirection of pedicle screws was performed. Fifty pedicle screws were redirected in these patients using cbCT-based 3D image guidance. They were graded pre- and post-operatively using an established grading system.

RESULTS

No complications occurred in this study as a result of redirection. No pedicle breach was noted in all of the redirected pedicle screws.

CONCLUSION

Redirection of misplaced pedicle screws using cbCT-based 3D image guidance seems to be safe and accurate in our experience. Further studies are needed to establish its safety, accuracy, fusion rate, and clinical outcome compared with other methods. Copyright © 2016 John Wiley & Sons, Ltd.