The accuracy of acetabular cup placement in primary total hip arthroplasty using an image-free navigation system

Background Intraoperative navigation systems have been shown to improve the accuracy of acetabular component insertion in total hip arthroplasty (THA). The purpose of this study was to investigate the accuracy of cup orientation in primary THA using an image-free navigation system. Methods A total of 107 consecutive cementless THAs using an image-free navigation system were performed from February 2017 to March 2020 (the navigation group). As a control group, 77 retrospective consecutive cases who underwent THAs with manual implant-techniques between February 2012 and April 2017 were included. Postoperative cup radiographic inclination and radiographic anteversion relative to the functional pelvic plane were assessed using a 3D-template system after computed tomography (CT) examination. Results The mean absolute errors of the postoperative measured angles from the target angles in inclination were 3.4° ± 3.0° in the navigation group and 8.4° ± 6.6° in the control group (p < 0.001). The mean absolute errors in anteversion were 5.1° ± 3.6° in the navigation group and 10.8° ± 6.5° in the control group (p < 0.001). The percentage of cups inside the Lewinnek safe zone was 93% in the navigation group and 44% in the control group (p < 0.001). The mean absolute values of navigation error were 3.3° ± 2.8° in inclination and 5.8° ± 4.9° in anteversion. Among the cases of osteoarthritis, the inclination error was significantly higher in Crowe group 2 to 4 than in Crowe group 1 (5.1° ± 3.5° and 3.0° ± 2.5°, respectively, p < 0.05). The percentage of hips with inclination error over 10° in Crowe group 2 to 4 was significantly higher than in Crowe group 1 (17 and 1%, respectively, p < 0.05). Conclusions The image-free navigation system improved the accuracy of cup orientation. The accuracy of cup position was less in Crowe group 2 to 4 than in Crowe group 1.

The Accuracy of Acetabular Cup Placement in Primary Total Hip Arthroplasty Using an Image-free Navigation System

Background: Intraoperative navigation systems have been shown to improve the accuracy of acetabular component insertion in total hip arthroplasty (THA). The purpose of this study was to investigate the accuracy of cup orientation in primary THA using an image-free navigation system.Methods: A total of 107 consecutive cementless THAs using an image-free navigation system were performed from February 2017 to March 2020 (the navigation group). As a control group, 77 retrospective consecutive cases who underwent THAs with manual implant-techniques between February 2012 and April 2017 were included. Postoperative cup radiographic inclination and radiographic anteversion relative to the functional pelvic plane were assessed using a 3D-template system after computed tomography (CT) examination.Results: The mean absolute errors of the postoperative measured angles from the target angles in inclination were 3.4°±3.0° in the navigation group and 8.4°±6.6° in the control group (p<0.001). The mean absolute errors in anteversion were 5.1° ± 3.6° in the navigation group and 10.8° ± 6.5° in the control group (p<0.001). The percentage of cups inside the Lewinnek safe zone was 93% in the navigation group and 44% in the control group (p<0.001). The mean absolute values of navigation error were 3.3° ± 2.8° in inclination and 5.8° ± 4.9° in anteversion. Among the cases of osteoarthritis, the inclination error was significantly higher in Crowe group 2 to 4 than in Crowe group 1 (5.1° ± 3.5° and 3.0° ± 2.5°, respectively, p<0.05). The percentage of hips with inclination error over 10° in Crowe group 2 to 4 was significantly higher than in Crowe group 1 (17% and 1%, respectively, p<0.05).Conclusions: The image-free navigation system improved the accuracy of cup orientation. The accuracy of cup position was less in Crowe group 2 to 4 than in Crowe group 1.

Stereotactic navigation versus ultrasound guidance in placing IRE applicators in a liver phantom

The aim of this study was to compare the accuracy of stereotactic CT-guided navigation and ultrasound guided navigation for placing electrodes in Irreversible electroporation in a liver phantom. A liver phantom with multiple tumours was used and interventionists placed four IRE electrodes around each tumour guided either by stereotactic CT-guided navigation or ultrasound. The goal was to place them in a perfect 20 × 20 mm square with parallel electrodes. After each treatment, a CT-scan was performed. The accuracy in pairwise electrode distance, pairwise parallelism and time per tumour was analysed. Eight interventionists placed four electrodes around 55 tumours, 25 with ultrasound and 30 with stereotactic CT-guided navigation. 330 electrode pairs were analysed, 150 with ultrasound and 180 with stereotactic CT-navigation. The absolute median deviation from the optimal distance was 1.3 mm (range 0.0 to 11.3 mm) in the stereotactic CT-navigation group versus 7.1 mm (range 0.3 to 18.1 mm) in the Ultrasound group (p < 0.001). The mean angle between electrodes in each pair was 2.7 degrees (95% CI 2.4 to 3.1 degrees) in the stereotactic CT-navigation group and 5.5 degrees (95% CI 5.0 to 6.1 degrees) in the Ultrasound group (p < 0.001). The mean time for placing the electrodes was 15:11 min (95% CI 13:05 to 17:18 min) in the stereotactic CT-navigation group and 6:40 min (95% CI 5:28 to 7:52 min) in the Ultrasound group. The use of stereotactic CT-navigation in placing IRE-electrodes in a liver phantom is more accurate, but more time consuming, compared to ultrasound guidance.

Comparative Study between Neuro-navigation and Intra-Operative Ultrasound in Excision of Intra-axial Brain Lesions

Background The application of imaging during surgery can improve patient outcomes by accurate and thorough removal of lesions while having minimal impact on healthy tissue. Aim of the Work to compare the use of neuronavigation to intraoperative ultrasound guidance in excision of intra-axial brain lesion. Patients and Methods This cohort study was conducted on 51 patients with intra-axial brain lesion is amenable to gross total resection. The primary outcome was extent of resection assessed using a non-volumetric technique. Other outcomes included the postoperative functional status and the rate of operative complications. Results There were 34 patients in the Neuronavigation group and 17 patients in the ultrasound group. The extent of resection was significantly better in the ultrasound group as the extent of tumor resection based on the GTR/NTR/STR method of assessment showed that the IOUS group had statistically significant higher chance of achieving GTR (29.4%) than the navigation group (8.8%). In the IOUS group near total and subtotal resection rates were 17% and 52% respectively. In neuronavigation group 11.8% and 79.4%. Conclusion application of ultrasound integrated in Neuronavigation system guidance in surgery excision of intra-axial brain lesions is a useful tool in achieving a higher extent of tumor resection (EOR).

No difference in long-term functional outcomes or survivorship after total knee arthroplasty with or without computer navigation: a 17-year survivorship analysis

Background The literature comparing the long-term outcomes and survivorship of computer navigation-assisted and conventional total knee replacement (TKR) is sparse. Moreover, of the available comparative studies with follow-up duration of more than 10 years, the results seem to be conflicting. The purpose of this long-term study was to compare the clinical and radiological outcomes, and implant survivorship, of TKR performed with and without computer navigation. Methods We retrospectively compared the results of 49 computer-navigated TKRs and 139 conventional TKRs. The mean age of the patients was 67.9 (range 52–81) years for the navigation group and 67.1 (range 50–80) years for the conventional TKR group. The mean duration of follow-up for the conventional and navigation TKR groups was 12.9 and 13.2 years, respectively. Clinical and radiographic follow-up examinations of the patients were performed at 2 weeks, 1 month, 3 months and 6 months post-operatively, and at 1-year intervals thereafter. Results There were no significant differences in the post-operative Knee Society knee and function score between the two groups. The mean overall deviation from neutral alignment and the radiological outliers were significantly higher in the conventional TKR group. The overall survival rates at 17 years were 92.9% for the navigation group and 95.6% for the conventional TKR group (p = 0.62). Conclusions Navigated TKR resulted in fewer radiological outliers; however, this did not translate to better long-term functional outcomes or implant survival.

Navigating in Virtual Environments: Does a Map or a Map-Based Description Presented Beforehand Help?

Background. One of the aims of research in spatial cognition is to examine the factors capable of optimizing environment learning from navigation, which can be examined using a virtual environment (VE). Different learning conditions can play an important part. Aim. This study examined the benefits of presenting configured information (layout with elements arranged in it) using a map or verbal description before a learner navigates in a new environment. Method. Ninety participants were assigned to three learning groups of 30 individuals (15 males and 15 females). Before participants navigated in a VE, one group was shown a map of the environment (“map before navigation”), a second group read a map-like description of the environment (“description before navigation”), and a third group started navigating without any prior input (“only navigation”). Participants then learned a path in a VE (presented as if they were driving a car). Their recall was subsequently tested using three types of task: (i) route retracing; (ii) pointing; (iii) path drawing. Several measures were administered to assess participants’ individual visuospatial and verbal factors. Results. There were no differences between the three groups in route retracing. The “map before navigation” group performed better than the “only navigation” group in both the pointing and the path drawing tasks, however, and also outperformed the “description before navigation” group in the path drawing task. Some relations emerged between participants’ individual difference factors and their recall performance. Conclusions. In learning from navigation, seeing a map beforehand benefits learning accuracy. Recall performance is also supported, at least in part, by individual visuospatial and verbal factors.

Comparison of implant placement accuracy in two different preoperative digital workflows: navigated vs. pilot-drill-guided surgery

Background The aim of the study is to evaluate the accuracy of a new implant navigation system on two different digital workflows. Methods A total of 18 phantom jaws consisting of hard and non-warping plastic and resembling edentulous jaws were used to stimulate a clinical circumstance. A conventional pilot-drill guide was conducted by a technician, and a master model was set by using this laboratory-produced guide. After cone beam computed tomography (CBCT) and 3D scanning of the master models, two different digital workflows (marker tray in CBCT and 3D-printed tray) were performed based on the Digital Imaging Communication in Medicine files and standard tessellation language files. Eight Straumann implants (4.1 mm × 10 mm) were placed in each model, six models for each group, resulting in 144 implant placements in total. Postoperative CBCT were taken, and deviations at the entry point and apex as well as angular deviations were measured compared to the master model. Results The mean total deviations at the implant entry point for MTC (marker tray in CBCT), 3dPT (3d-printed tray), and PDG (pilot-drill guide) were 1.024 ± 0.446 mm, 1.027 ± 0.455 mm, and 1.009 ± 0.415 mm, respectively, and the mean total deviations at the implant apex were 1.026 ± 0.383 mm, 1.116 ± 0.530 mm, and 1.068 ± 0.384 mm. The angular deviation for the MTC group was 2.22 ± 1.54°. The 3dPT group revealed an angular deviation of 1.95 ± 1.35°, whereas the PDG group showed a mean angular deviation of 2.67 ± 1.58°. Although there were no significant differences among the three groups (P > 0.05), the navigation groups showed lesser angular deviations compared to the pilot-drill-guide (PDG) group. Implants in the 3D-printed tray navigation group showed higher deviations at both entry point and apex. Conclusions The accuracy of the evaluated navigation system was similar with the accuracy of a pilot-drill guide. Accuracy of both preoperative workflows (marker tray in CBCT or 3D-printed tray) was reliable for clinical use.

Navigated iliac screw placement may reduce radiation and OR time in lumbopelvic fixation of unstable complex sacral fractures

Purpose Instability of the posterior pelvic ring may be stabilized by lumbopelvic fixation. The optimal osseous corridor for iliac screw placement from the posterior superior iliac spine to the anterior inferior iliac spine requires multiple ap- and lateral-views with additional obturator-outlet and -inlet views. The purpose of this study was to determine if navigated iliac screw placement for lumbopelvic fixation influences surgical time, fluoroscopy time, radiation exposure, and complication rates. Methods Bilateral lumbopelvic fixation was performed in 63 patients. Implants were inserted as previously described by Schildhauer. A passive optoelectronic navigation system with surface matching on L4 was utilized for navigated iliac screw placement. To compare groups, demographics were assessed. Operative time, fluoroscopic time, and radiation were delineated. Results Conventional fluoroscopic imaging for lumbopelvic fixation was performed in 32 patients and 31 patients underwent the procedure with navigated iliac screw placement. No differences were found between the groups regarding demographics, comorbidities, or additional surgical procedures. Utilization of navigation led to fluoroscopy time reduction of more than 50% (3.2 vs. 8.6 min.; p < 0.001) resulting in reduced radiation (2004.5 vs. 5130.8 Gy*cm2; p < 0.001). Operative time was reduced in the navigation group (176.7 vs. 227.4 min; p = 0.002) despite the necessity of additional surface referencing. Conclusion For iliac screws, identifying the correct entry point and angle of implantation requires detailed anatomic knowledge and multiple radiographic views. In our study, additional navigation reduced operative time and fluoroscopy time resulting in a significant reduction of radiation exposure for patients and OR personnel.

Remotely delivered environmental enrichment intervention for traumatic brain injury: Study protocol for a randomised controlled trial

IntroductionIndividuals with moderate-severe traumatic brain injury (m-sTBI) experience progressive brain and behavioural declines in the chronic stages of injury. Longitudinal studies found that a majority of patients with m-sTBI exhibit significant hippocampal atrophy from 5 to 12 months post-injury, associated with decreased cognitive environmental enrichment (EE). Encouragingly, engaging in EE has been shown to lead to neural improvements, suggesting it is a promising avenue for offsetting hippocampal neurodegeneration in m-sTBI. Allocentric spatial navigation (ie, flexible, bird’s eye view approach), is a good candidate for EE in m-sTBI because it is associated with hippocampal activation and reduced ageing-related volume loss. Efficacy of EE requires intensive daily training, prohibitive within most current health delivery systems. The present protocol is a novel, remotely delivered and self-administered intervention designed to harness principles from EE and allocentric spatial navigation to offset hippocampal atrophy and potentially improve hippocampal functions such as navigation and memory for patients with m-sTBI.Methods and analysisEighty-four participants with chronic m-sTBI are being recruited from an urban rehabilitation hospital and randomised into a 16-week intervention (5 hours/week; total: 80 hours) of either targeted spatial navigation or an active control group. The spatial navigation group engages in structured exploration of different cities using Google Street View that includes daily navigation challenges. The active control group watches and answers subjective questions about educational videos. Following a brief orientation, participants remotely self-administer the intervention on their home computer. In addition to feasibility and compliance measures, clinical and experimental cognitive measures as well as MRI scan data are collected pre-intervention and post-intervention to determine behavioural and neural efficacy.Ethics and disseminationEthics approval has been obtained from ethics boards at the University Health Network and University of Toronto. Findings will be presented at academic conferences and submitted to peer-reviewed journals.Trial registration numberVersion 3, ClinicalTrials.gov Registry (NCT04331392).

The Impact of Intraoperative Image-Guidance Modalities and Neurophysiologic Monitoring in the Safety of Sacroiliac Fusions

Study Design: Retrospective observational cohort. Objective: A review of efficiency and safety of fluoroscopy and stereotactic navigation system for minimally invasive (MIS) Sacroiliac (SI) fusion through a lateral technique. Methods: Retrospective analysis of an observational cohort of 96 patients greater than 18 years old, that underwent MIS SI fusion guided by fluoroscopy or navigation between January 2013 and April 2020 with a minimum of 3 months follow-up. Intraoperative neuromonitoring (IONM) with a variable combination of electromyography (EMG), somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) was also utilized. Results: The overall complication rate in the study was 9.4%, and there was no difference between the fluoroscopy (10.1%), and navigation groups (8%). Neurological complication rate was 2.1%, without a significant difference between both intraoperative guidance modality groups (p = 0.227). There was a significant difference between the modalities of IONM used and the occurrence of neurological injury (p = 0.01).The 2 patients who had a neurological complication postoperatively were monitored only with EMG and SSEP, but none of the patients (n = 76) in which MEPs were utilized had neurologic complication. The mean pain improvement 3 months after surgery was greater in the navigation group (2.44 ± 2.72), but was not statistically different than the improvement in the fluoroscopy group (1.90 ± 2.07) (p = 0.301). Conclusions: No difference in the safety of the procedure was found between the fluoroscopy and the stereotactic navigation techniques. The contribution of the IONM to the safety of SI fusions could not be determined, but the data indicates that MEPs provide the highest level of sensitivity.