Role of 3D intraoperative imaging in orthopedic and trauma surgery

Skyline view versus intraoperative 3D fluoroscopy for dorsal screw protrusion identification following volar plating in the treatment of distal radial fracture

BACKGROUND

Dorsal screw protrusion can lead to complications such as extensor pollicis longus (EPL) tear or rupture after volar locking plate (VLP) fixation. Previous studies displayed that intraoperative 3D fluoroscopy and skyline view had similar diagnostic accuracy. This study investigated the efficacy of intraoperative 3D fluoroscopy compared to skyline view for detecting dorsal cortex screw protrusion in VLP procedures for unstable intra-articular distal radius fractures (DRF). We used postoperative computed tomography (CT) to assess the efficacy and addressed the limitations of previous methods in evaluating screw penetration accurately.

METHODS

We utilized the ICUC database, a prospective cohort of patients with surgically treated DRF, to collect cases with available images, including skyline views, intraoperative 3D fluoroscopy, and postoperative CT scans. The postoperative CT confirmed whether the screw protruded through the dorsal cortex. The interrater reliability was assessed using Cohen's Kappa, and a diagnostic test was utilized to compare the two intraoperative imaging modalities.

RESULTS

Twenty-one unstable DRFs were included in the study. The agreement between skyline view and postoperative CT was moderate agreement, with a kappa value of 0.481 (95% CI: 0.297-0.652, N = 84), identifying 10 uncertain, 56 shorter screws, and 18 screw penetrations. Intraoperative 3D fluoroscopy demonstrated almost perfect agreement with postoperative CT, with a kappa of 0.839 (95% CI: 0.703-0.975, N = 84), identifying 62 shorter screws and 22 screw penetrations. The sensitivity and specificity of intraoperative 3D fluoroscopy in detecting dorsal screw protrusion were 81.8% and 98.4%, respectively, while the skyline view's sensitivity and specificity were 72.2% and 90.9%.

CONCLUSION

3D fluoroscopy offers an almost perfect evaluation, whereas the skyline views provide only moderate agreement. 3D fluoroscopy could reduce cumulative radiation exposure of surgeon and patient compared to skyline view. Clinically, 3D fluoroscopy would be beneficial for surgeons to evaluate dorsal screw protrusion precisely and safely.

Effect of the cone-beam CT acquisition trajectory on image quality in spine surgery: experimental cadaver study

BACKGROUND

Intraoperative 3D imaging with cone-beam CT (CBCT) improves assessment of implant position and reduces complications in spine surgery. It is also used for image-guided surgical techniques, resulting in improved quality of care. However, in some cases, metal artifacts can reduce image quality and make it difficult to assess pedicle screw position and reduction.

PURPOSE

The objective of this study was to investigate whether a change in CBCT acquisition trajectory in relation to pedicle screw position during dorsal instrumentation can reduce metal artifacts and consequently improve image quality and clinical assessability.

STUDY DESIGN

Experimental cadaver study.

METHODS

A human cadaver was instrumented with pedicle screws in the thoracic and lumbar spine region (Th11 to L5). Then, the acquisition trajectory of the CBCT (Cios Spin, Siemens, Germany) to the pedicle screws was systematically changed in 5° steps in angulation (-30° to +30°) and swivel (-25° to +25°). Subsequently, radiological evaluation was performed by 3 blinded, qualified raters on image quality using 9 questions (including anatomical structures, implant position, appearance of artifacts) with a score (1-5 points). For statistical evaluation, the image quality of the different acquisition trajectories was compared to the standard acquisition trajectory and checked for significant differences.

RESULTS

The angulated acquisition trajectory significantly increased the score for subjective image quality (p<.001) as well as the clinical assessability of pedicle screw position (p<.001) with particularly strong effects on subjective image quality in the vertebral pedicle region (d=1.61). Swivel of the acquisition trajectory significantly improved all queried domains of subjective image quality (p<.001) as well as clinical assessability of pedicle screw position (p<.001).

CONCLUSIONS

In this cadaver study, the angulation as well as the swivel of the acquisition trajectory led to a significantly improved image quality in intraoperative 3D imaging (CBCT) with a constant isocenter. The data show that maximizing the angulation/swivel angle towards 30°/25° provides the best tested subjective image quality and enhances clinical assessability. Therefore, a correct adjustment of the acquisition trajectory can help to make intraoperative revision decisions more reliably.

CLINICAL SIGNIFICANCE

The knowledge of enhanced image quality by changing the acquisition trajectory in intraoperative 3D imaging can be used for the assessment of critical screw positions in spine surgery. The implementation of this knowledge requires only a minor change of the current intraoperative imaging workflow without additional technical equipment and could further reduce the need for revision surgery.

Evaluating the Status and Promising Potential of Robotic Spinal Surgery Systems

The increasing frequency of cervical and lumbar spine disorders, driven by aging and evolving lifestyles, has led to a rise in spinal surgeries using pedicle screws. Robotic spinal surgery systems have emerged as a promising innovation, offering enhanced accuracy in screw placement and improved surgical outcomes. We focused on literature of this field from the past 5 years, and a comprehensive literature search was performed using PubMed and Google Scholar. Robotic spinal surgery systems have significantly impacted spinal procedures by improving pedicle screw placement accuracy and supporting various techniques. These systems facilitate personalized, minimally invasive, and low-radiation interventions, leading to greater precision, reduced patient risk, and decreased radiation exposure. Despite advantages, challenges such as high costs and a steep learning curve remain. Ongoing advancements are expected to further enhance these systems' role in spinal surgery.

Image Quality Comparison of Three 3D Mobile X-Ray Imaging Guidance Devices Used in Spine Surgery: A Phantom Study

An image-quality CT phantom was scanned with three different 3D X-ray imaging guidance devices in the operating theatre: O-Arm, Loop-X, and Airo TruCT. Default acquisition and reconstruction parameters for lumbar spine procedures were used on each device. The tube current was set to a dose level of around 27 mGy. A task-based image quality assessment was performed by calculating the noise power spectrum (NPS) and task transfer function (TTF). A detectability index (d') was calculated for three simulated bone lesions. The noise magnitude of the O-Arm was higher than the Airo TruCT, and the Loop-X had higher noise than the Airo TruCT. The highest average NPS frequency was for the O-Arm images, and the lowest was for the Loop-X. The TTFs at 50% values were similar for the Airo TruCT and Loop-X devices. Compared to Airo TruCT, the TTF at 50% value increased with the O-Arm by 53.12% and 41.20% for the Teflon and Delrin inserts, respectively. Compared to Airo TruCT, the d' value was lower with Loop-X by -26.73%, -27.02%, and -23.95% for lytic lesions, sclerotic lesions, and high-density bone, respectively. Each 3D-imaging spine surgery guidance device has its own strengths and weaknesses in terms of image quality. Cone-beam CT systems apparently offer the best compromise between noise and spatial resolution for spine surgery.

Navigation and 3D-imaging in pelvic ring surgery: a systematic review of prospective comparative studies

BACKGROUND

Few literature reviews have been published focusing on navigation, robotic or pre-operative planning using 3D-imaging technology (3D-printing, 3D-planning). To our knowledge, no reviews have been performed to assess and compare all these modalities together versus control groups (conventional fluoroscopy) through high Randomized Control Trials (RCTs) and Prospective Control Studies (PCSs). The aim of this study was to assess and compare 3D-imaging technologies from pre-operative planning to per-operative navigation and robotic in the management of pelvic ring fractures through high level studies.

METHODS

A literature search was performed using PubMed, the Cochrane library and Google scholar using keywords up to December 2023. Only prospective comparative studies (RCT and PCS) were included. A total of 341 articles were identified, 39 articles were selected for full-text analysis leaving 7 articles included in this literature systematic review.

RESULTS

A trend towards improved precision in screw placement and reduction of radiation exposure without consequences in term of functional outcomes have been identified. No conclusions can be extrapolated regarding operative time and blood loss except for robotic which improve these parameters because robotic arm assistance help surgeons to correctly follow the planning based on 2D-fluoroscopy. Surgery duration and radiation dose are significantly reduced with robotic-arm assistance for the same reasons. With navigation the results have to be nuanced according to the experience of the surgical team. Interest of navigation is emphasized in sacral dysmorphism in comparison with conventional fluoroscopy. This highlights the benefits of navigation for ilio-sacral screw placement in difficult cases and less experimented teams.

CONCLUSION

High level studies which assess and compare 3D-imaging technologies from pre-operative planning to per-operative navigation and robotic in the management of pelvic ring fractures are low. To date and according to the present high level literature, navigation and 3D-technologies in pelvic ring surgery should be recommended for difficult cases.

LEVEL OF EVIDENCE, II

Systematic review of Level II studies.

Functional Acetabular Component Positioning During Direct Anterior Approach Hip Arthroplasty Using a Novel Three-Dimensional Virtual Mesh Imaging System With Fluoroscopy

BACKGROUND

Optimal position of total hip arthroplasty (THA) components is critical for joint mechanics and stability. Acetabular component positioning during supine surgery in direct anterior approach (DAA) THA may be different in the standing position postoperatively, which traditional fluoroscopy is unable to predict. A novel 3-dimensional (3D) image analysis technology (IAT) that uses artificial intelligence to measure the tilt and rotation of the pelvis has enabled prediction of component positioning from supine to standing. The purpose of this study was to compare intraoperative fluoroscopy, non-3D-IAT, and 3D-IAT with postoperative standing radiographs to assess the accuracy of component positioning.

METHODS

From 2022 to 2023, 30 consecutive patients (86.6% women, mean age 59 [range, 55 to 67]) undergoing primary DAA THA with the use of the 3D-IAT were identified. A separate cohort of 148 patients from 2020 to 2021 (85% women, mean age 65 [range, 55 to 69]) who underwent DAA THA with non-3D-IAT was used for comparison. Leg length discrepancy (LLD), cup anteversion, and inclination were manually measured on intraoperative fluoroscopic images and digitally measured using IAT. Follow-up evaluation occurred at 1 month with standing pelvis radiographs measured using Ein Bild Röntgen Analyze-Cup software. Measurements were compared via Wilcoxon signed rank tests where P ≤ .05 indicates significantly different measurements.

RESULTS

Median LLD, inclination, and anteversion measurements via non-3D-IAT and fluoroscopy were significantly different compared to postoperative standing radiographs (P < .001). The 3D-IAT more accurately predicted LLD, abduction, and anteversion, with values not significantly different from postoperative standing measurements (P = .23, P = .93, and P = .36, respectively).

CONCLUSIONS

The use of the 3D-IAT during DAA THA allowed for the more accurate prediction of acetabular component position in the standing position postoperatively.

Radiation shielding calculation for interventional radiology: An updated workload survey using a dose monitoring software

Shielding design is an essential aspect of radiation protection. It is necessary to ensure that barriers safeguard workers, patients, the general public, and the environment from the harmful radiation emitted by X-ray machines. The National Council on Radiation Protection and Measurements (NCRP) 147 method is widely accepted within the radiation protection experts' (RPEs) community for structural shielding design for medical X-ray imaging facilities. However, these indications are based on data collected in 1996. In recent years, interventional radiology procedures have seen significant developments. Therefore, it is important to evaluate whether updating the data on workload in the different specialities is necessary. We extracted all interventional radiology exposure data parameters from three angiographs from two vendors using dose monitoring software for 3066 procedures and 214,697 individual exposures. The workload distribution as a function of the kVp for five interventional rooms was calculated by summing all exposures and then normalising them by the number of patients. Analysing this data, we obtained new transmission curves through lead, concrete and gypsum wallboard, finding the parameters (α, β, and γ) in the Archer equation for the secondary radiation. Finally, our aim was to share an example of shielding calculations for haemodynamics and neuroangiography rooms to illustrate the impact of updated transmission data.

Dual-Source CBCT for Larger Longitudinal Coverage: System Design and Image Reconstruction

The application of CBCT systems in intraoperative environments has become increasingly common, but concurrent CBCT systems are unsuitable for situations that require a large longitudinal imaging FoV, such as orthopedics. To increase longitudinal coverage, we developed a dual-source CBCT (DS-CBCT) system in which two ray sources are symmetrically placed along the central plane. After further analyzing its geometric characteristics, we propose an analytical reconstruction algorithm termed DT-FDK specialized for DS-CBCT, which combines cone-beam rebinning and two rays with smaller cone angles among the four conjugate rays to further suppress cone beam artifacts. The system design and reconstruction algorithm are tested on both simulated and real-scanned data. Results show that the DS-CBCT can expand the effective imaging volume by 37.1% compared to single-source CBCT systems. The reconstructed images by DT-FDK also show improved image quality compared to traditional reconstruction algorithms.

Comparison of iCT-based navigation and fluoroscopic-guidance for atlantoaxial screw placement in 78 patients with traumatic cervical spine injuries

BACKGROUND CONTEXT

Studies have shown biomechanical superiority of cervical pedicle screw placement over other techniques. However, accurate placement is challenging due to the inherent risk of neurovascular complications. Navigation technology based on intraoperative 3D imaging allows highly accurate screw placement, yet studies specifically investigating screw placement in patients with traumatic atlantoaxial injuries are scarce. The aim of this study was to compare atlantoaxial screw placement as treatment of traumatic instabilities using iCT-based navigation or fluoroscopic-guidance with intraoperative 3D control scans.

METHODS

This was a retrospective review of patients with traumatic atlantoaxial injuries treated operatively with dorsal stabilization of C1 and C2. Patients were either assigned to the intraoperative navigation or fluoroscopic-guidance group. Screw accuracy, procedure time, and revisions were compared.

RESULTS

Seventy-eight patients were included in this study with 51 patients in the navigation group and 27 patients in the fluoroscopic-guidance group. In total, 312 screws were placed in C1 and C2. Screw accuracy was high in both groups; however, pedicle perforations > 1 mm occurred significantly more often in the fluoroscopic-guidance group (P = 0.02). Procedure time was on average 23 min shorter in the navigation group (P = 0.02).

CONCLUSIONS

This study contributes to the available data showing that navigated atlantoaxial screw placement proves to be feasible as well as highly accurate compared to the fluoroscopic-guidance technique without prolonging the time needed for surgery. When comparing these data with other studies, the application of different classification systems for assessment of screw accuracy should be considered.

Effects of long-term X-ray exposure on CBC among radiological department staff in Sulaimani city

Objectives

Ionizing rays used in radiology devices are believed to affect the body tissues of radiology department employees. This study was aimed at comparing the effects of long-term exposure to X-rays on the blood cells of staff working in the radiology departments of several hospitals in the Sulaimani City/Kurdistan region government.

Methods

This cross-sectional study was conducted from 2021 to 2022 on 250 employees-including radiologists, radiographers, and other medical staff such as physicians or nurses-in the radiology departments of hospitals in the city of Sulaimani, Kurdistan region government. Data were collected with a questionnaire completed by the participants after verbal consent was provided. Blood samples were collected from 250 radiology staff and sent to a laboratory for measurement of blood parameters. The collected data were analyzed in SPSS version 26 software, and relationships in the data were investigated with descriptive statistical tests, Student's t test, and ANOVA.

Results

Most male participants were radiographers with a diploma degree. A statistically significant difference in RBC, HCT %, MCV, and PCT blood parameters was observed between sexes. Moreover, statistically significant differences were observed in RDW-CV and RDW-SD between occupational groups; in mean WBC and lymphocytes among staff who were current, never, or former smokers; and in mean WBC among employees who were current, never, or former drinkers (p < 0.01).

Conclusion

Blood parameters such as RDW-CV and RDW-SD were concluded to be affected by job type and X-ray exposure duration.

Navigated pedicle screw insertion with the Surgivisio system: Malposition rate and risk factors - about 648 screws

PURPOSE

Pedicle screw malposition rates vary greatly in scientific literature depending on the chosen criteria. Different techniques have been developed to lower the risk of screw malposition. Our primary objective is to evaluate the malposition rate associated with the use of the Surgivisio navigation system and to identify risk factors for screw malposition. The secondary objectives are to assess operating time and radiation data.

MATERIALS AND METHODS

We performed a monocentric retrospective consecutive case series. All patients operated for pedicle screw implantation using the Surgivisio system between September 2017 and June 2020 were included. Screw positioning was evaluated on postoperative CT scans using Heary and Gertzbein classifications. Thirteen potential risk factors for screw malposition were hypothesized and tested with a univariate and multivariate analysis.

RESULTS

Six hundred and forty-eight screws could be evaluated in 97 patients. Our study reported a 92.4% satisfactory screw implantation rate with a mean operative time per screw of 14.5±6.7minutes and a patient effective dose of 0.47±0.31 mSv per screw. One screw was neurotoxic and required an early revision (0.15%). Three risk factors for screw malposition have been identified in a multivariate analysis: female gender (OR=2.13 [1.11; 4], p=0.0219), an implantation level above D10 (OR=2.17 [1.13; 4.16], p=0.0197), and an "open" surgery (as opposed to percutaneous) (OR=3.47 [1.83; 6.56], p=0.0002).

CONCLUSION

Pedicle screw malposition rate and operative time with the Surgivisio navigation system are comparable with those reported in scientific literature. We theorized that intraoperative patient reference displacement could be a major cause of navigation failure.

LEVEL OF EVIDENCE

IV.

Current Trends in Artificial Intelligence-Assisted Spine Surgery: A Systematic Review

This systematic review summarizes existing evidence and outlines the benefits of artificial intelligence-assisted spine surgery. The popularity of artificial intelligence has grown significantly, demonstrating its benefits in computer-assisted surgery and advancements in spinal treatment. This study adhered to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), a set of reporting guidelines specifically designed for systematic reviews and meta-analyses. The search strategy used Medical Subject Headings (MeSH) terms, including "MeSH (Artificial intelligence)," "Spine" AND "Spinal" filters, in the last 10 years, and English- from January 1, 2013, to October 31, 2023. In total, 442 articles fulfilled the first screening criteria. A detailed analysis of those articles identified 220 that matched the criteria, of which 11 were considered appropriate for this analysis after applying the complete inclusion and exclusion criteria. In total, 11 studies met the eligibility criteria. Analysis of these studies revealed the types of artificial intelligence-assisted spine surgery. No evidence suggests the superiority of assisted spine surgery with or without artificial intelligence in terms of outcomes. In terms of feasibility, accuracy, safety, and facilitating lower patient radiation exposure compared with standard fluoroscopic guidance, artificial intelligence-assisted spine surgery produced satisfactory and superior outcomes. The incorporation of artificial intelligence with augmented and virtual reality appears promising, with the potential to enhance surgeon proficiency and overall surgical safety.

A spatial registration method based on 2D-3D registration for an augmented reality spinal surgery navigation system

BACKGROUND

In order to provide accurate and reliable image guidance for augmented reality (AR) spinal surgery navigation, a spatial registration method has been proposed.

METHODS

In the AR spinal surgery navigation system, grayscale-based 2D/3D registration technology has been used to register preoperative computed tomography images with intraoperative X-ray images to complete the spatial registration, and then the fusion of virtual image and real spine has been realised.

RESULTS

In the image registration experiment, the success rate of spine model registration was 90%. In the spinal model verification experiment, the surface registration error of the spinal model ranged from 0.361 to 0.612 mm, and the total average surface registration error was 0.501 mm.

CONCLUSION

The spatial registration method based on 2D/3D registration technology can be used in AR spinal surgery navigation systems and is highly accurate and minimally invasive.

Carbon nanotube-based multiple source C-arm CT system: feasibility study with prototype system

To extend the field of view while reducing dimensions of the C-arm, we propose a carbon nanotube (CNT)-based C-arm computed tomography (CT) system with multiple X-ray sources. A prototype system was developed using three CNT X-ray sources, enabling a feasibility study. Geometry calibration and image reconstruction were performed to improve the quality of image acquisition. However, the geometry of the prototype system led to projection truncation for each source and an overlap region of object area covered by each source in the two-dimensional Radon space, necessitating specific corrective measures. We addressed these problems by implementing truncation correction and applying weighting techniques to the overlap region during the image reconstruction phase. Furthermore, to enable image reconstruction with a scan angle less than 360°, we designed a weighting function to solve data redundancy caused by the short scan angle. The accuracy of the geometry calibration method was evaluated via computer simulations. We also quantified the improvements in reconstructed image quality using mean-squared error and structural similarity. Moreover, detector lag correction was applied to address the afterglow observed in the experimental data obtained from the prototype system. Our evaluation of image quality involved comparing reconstructed images obtained with and without incorporating the geometry calibration results and images with and without lag correction. The outcomes of our simulation study and experimental investigation demonstrated the efficacy of our proposed geometry calibration, image reconstruction method, and lag correction in reducing image artifacts.

Effect of changing the acquisition trajectory of the 3D C-arm (CBCT) on image quality in spine surgery: experimental study using an artificial bone model

BACKGROUND

Intraoperative 3D imaging using cone-beam CT (CBCT) provides improved assessment of implant position and reduction in spine surgery, is used for navigated surgical techniques, and therefore leads to improved quality of care. However, in some cases the image quality is not sufficient to correctly assess pedicle screw position and reduction, especially due to metal artifacts. The aim of this study was to investigate whether changing the acquisition trajectory of the CBCT in relation to the pedicle screw position during dorsal instrumentation of the spine can reduce metal artifacts and consequently improve image quality as well as clinical assessability on the artificial bone model.

METHODS

An artificial bone model was instrumented with pedicle screws in the thoracic and lumbar spine region (Th10 to L5). Then, the acquisition trajectory of the CBCT (Cios Spin, Siemens, Germany) to the pedicle screws was systematically changed in 5° steps in angulation (- 30° to + 30°) and swivel (- 30° to + 30°). Subsequently, radiological evaluation was performed by three blinded, qualified raters on image quality using 9 questions (including anatomical structures, implant position, appearance of artifacts) with a score (1-5 points). For statistical evaluation, the image quality of the different acquisition trajectories was compared to the standard acquisition trajectory and checked for significant differences.

RESULTS

The angulated acquisition trajectory increased the score for subjective image quality (p < 0.001) as well as the clinical assessability of pedicle screw position (p < 0.001) highly significant with particularly strong effects on subjective image quality in the vertebral pedicle region (d = 1.06). Swivel of the acquisition trajectory significantly improved all queried domains of subjective image quality (p < 0.001) as well as clinical assessability of pedicle screw position (p < 0.001). The data show that maximizing the angulation or swivel angle toward 30° provides the best tested subjective image quality. Angulation and swivel of the acquisition trajectory result in a clinically relevant improvement in image quality in intraoperative 3D imaging (CBCT) during dorsal instrumentation of the spine.

[Possibilities and limits of intraoperative 2D imaging in trauma surgery]

BACKGROUND

The two-dimensional (2D) imaging represents an essential and cost-effective component of intraoperative position control in fracture stabilization, even in the era of new three-dimensional (3D) imaging capabilities.

OBJECTIVE

The aim of the present study, in addition to a current literature review, was to examine whether the intraoperative use of 2D images leads to a quality of fracture reduction comparable to postoperative computed tomographic (CT) analysis including 3D reconstructions.

MATERIAL AND METHODS

A comparative retrospective analysis of intraoperative 2D and postoperative 3D image data was performed on 21 acetabular fractures stabilized via a pararectus approach according to an established protocol using the Matta criteria.

RESULTS

The assessment of fracture reduction in intraoperative fluoroscopy compared with postoperative CT revealed a difference only in one case with respect to the categorization of the joint step reduction in the main loading zone.

CONCLUSION

In the intraoperative use of 2D imaging for fracture treatment it is important to select the correct adjustment planes taking the anatomical conditions into account in order to achieve optimum assessability. In this way, the reduction result can be adequately displayed in fluoroscopy and is also comparable to the postoperative CT control. In addition, depending on the findings, optional intraoperative dynamic fluoroscopic assessment can have a direct influence on the further surgical procedure.

[Innovative 3D imaging]

Intraoperative 2D fluoroscopy is often performed for repositioning and implant control. However, this does not always provide the details needed to reliably detect joint steps or incorrect repositioning. Over the last few years, intraoperative 3D imaging has been established and further developed. Multiple studies demonstrate an advantage and better intraoperative control through 3D imaging. Examples are the upper ankle, the proximal tibia and the distal radius; the rates of intraoperative revisions with digital volume tomography (DVT) are between 20-30%. Technical advancements, such as metal artifact reductions, automated plane setting, automated screw detection, and robotic DVT devices, facilitate intraoperative operation, shorten surgical time, and provide improved image quality. By processing the data sets in the form of an immersive, computer-simulated image in terms of "augmented reality" (AR), increased precision can be achieved intraoperatively while reducing radiation exposure. The implementation of these systems is associated with costs, which are offset by cost savings from avoided revisions. Adequate counter-financing is still lacking at the present time. Intraoperative 3D imaging represents an important tool for intraoperative control. The current data situation makes it necessary to address the routine use of 3D procedures, especially in the joint area. The indications are becoming increasingly broader. Technical innovations such as robotics and AR have significantly improved 3D devices in recent years and offer high potential for integration into the OR.

Use of 3D Fluoroscopy to Assist in the Reduction and Fixation of Pelvic and Acetabular Fractures: A Safety and Quality Case Series

SUMMARY

Multidimensional fluoroscopy has been increasingly used in orthopaedic trauma to improve the intraoperative assessment of articular reductions and implant placement. Owing to the complex osteology of the pelvis, cross-sectional imaging is imperative for accurate evaluation of pelvic ring and acetabular injuries both preoperatively and intraoperatively. The continued development of fluoroscopic technology over the past decade has resulted in improved ease of intraoperative multidimensional fluoroscopy use in pelvic and acetabular surgery. This has provided orthopaedic trauma surgeons with a valuable tool to better evaluate reduction and fixation at different stages during operative treatment of these injuries. Specifically, intraoperative 3D fluoroscopy during treatment of acetabulum and pelvis injuries assists with guiding intraoperative decisions, assessing reductions, ensuring implant safety, and confirming appropriate fixation. We outline the useful aspects of this technology during pelvic and acetabular surgery and report its utility with a consecutive case series at a single institution. The added benefits of this technology have improved the ability to effectively manage patients with pelvis and acetabulum injuries.

PDS-MAR: a fine-grained projection-domain segmentation-based metal artifact reduction method for intraoperative CBCT images with guidewires

Objective.Since the invention of modern Computed Tomography (CT) systems, metal artifacts have been a persistent problem. Due to increased scattering, amplified noise, and limited-angle projection data collection, it is more difficult to suppress metal artifacts in cone-beam CT, limiting its use in human- and robot-assisted spine surgeries where metallic guidewires and screws are commonly used.Approach.To solve this problem, we present a fine-grained projection-domain segmentation-based metal artifact reduction (MAR) method termed PDS-MAR, in which metal traces are augmented and segmented in the projection domain before being inpainted using triangular interpolation. In addition, a metal reconstruction phase is proposed to restore metal areas in the image domain.Main results.The proposed method is tested on both digital phantom data and real scanned cone-beam computed tomography (CBCT) data. It achieves much-improved quantitative results in both metal segmentation and artifact reduction in our phantom study. The results on real scanned data also show the superiority of this method.Significance.The concept of projection-domain metal segmentation would advance MAR techniques in CBCT and has the potential to push forward the use of intraoperative CBCT in human-handed and robotic-assisted minimal invasive spine surgeries.

Radiation exposure for pedicle screw placement with three different navigation system and imaging combinations in a sawbone model

BACKGROUND

Studies have shown that pedicle screw placement using navigation can potentially reduce radiation exposure of surgical personnel compared to conventional methods. Spinal navigation is based on an interaction of a navigation software and 3D imaging. The 3D image data can be acquired using different imaging modalities such as iCT and CBCT. These imaging modalities vary regarding acquisition technique and field of view. The current literature varies greatly in study design, in form of dose registration, as well as navigation systems and imaging modalities analyzed. Therefore, the aim of this study was a standardized comparison of three navigation and imaging system combinations in an experimental setting in an artificial spine model.

METHODS

In this experimental study dorsal instrumentation of the thoracolumbar spine was performed using three imaging/navigation system combinations. The system combinations applied were the iCT/Curve, cCBCT/Pulse and oCBCT/StealthStation. Referencing scans were obtained with each imaging modality and served as basis for the respective navigation system. In each group 10 artificial spine models received bilateral dorsal instrumentation from T11-S1. 2 referencing and control scans were acquired with the CBCTs, since their field of view could only depict up to five vertebrae in one scan. The field of view of the iCT enabled the depiction of T11-S1 in one scan. After instrumentation the region of interest was scanned again for evaluation of the screw position, therefore only one referencing and one control scan were obtained. Two dose meters were installed in a spine bed ventral of L1 and S1. The dose measurements in each location and in total were analyzed for each system combination. Time demand regarding screw placement was also assessed for all system combinations.

RESULTS

The mean radiation dose in the iCT group measured 1,6 ± 1,1 mGy. In the cCBCT group the mean was 3,6 ± 0,3 mGy and in the oCBCT group 10,3 ± 5,7 mGy were measured. The analysis of variance (ANOVA) showed a significant (p < 0.0001) difference between the three groups. The multiple comparisions by the Kruskall-Wallis test showed no significant difference for the comparison of iCT and cCBCT (p1 = 0,13). Significant differences were found for the direct comparison of iCT and oCBCT (p2 < 0,0001), as well as cCBCT and oCBCT (p3 = 0,02). Statistical analysis showed that significantly (iCT vs. oCBCT p = 0,0434; cCBCT vs. oCBCT p = 0,0083) less time was needed for oCBCT based navigated pedicle screw placement compared to the other system combinations (iCT vs. cCBCT p = 0,871).

CONCLUSION

Under standardized conditions oCBCT navigation demanded twice as much radiation as the cCBCT for the same number of scans, while the radiation exposure measured for the iCT and cCBCT for one scan was comparable. Yet, time effort was significantly less for oCBCT based navigation. However, for transferability into clinical practice additional studies should follow evaluating parameters regarding feasibility and clinical outcome under standardized conditions.

Change of vertebral orientation, between the supine position and the prone position

PURPOSE

Our aim was to assess the change of vertebral orientation, expressed in the sagittal plane, in the transversal plane and in the frontal plane, at each level from T1 to S1 between the supine position (like in in a CT scan) and the prone position lying on bolsters like in an OR.

METHODS

Thirty-six patients were selected and included for a total number of one hundred and forty-eight vertebral levels. There were 30 females and 6 males. The mean age was 15 years and 9 months. A semi-automatic image processing technique and software (3D slicer), with a custom-made python script add-on, was used for each patient: paired preoperative CT scan and intraoperative cone beam computed tomography (CBCT) scan were processed to acquire complete spinal reconstructions in a consistent 3D coordinate system. The aim was to automatically compute a set of sagittal, transversal, and frontal rotations of each vertebral level of the same patient describing the 3D vertebral rotation between the supine position and the prone position lying on bolsters.

RESULTS

For sagittal analysis, the results showed a behavior in the evolution of rotation depending on the level. Between T01 and T10, the rotation was between - 14° and - 8°. Between T10 and L05, the sagittal rotation increased from - 10° up to + 10°. For frontal and transversal analysis, the rotations were under 6.5°.

CONCLUSION

These results could be valuable to perform a safe virtual templating: the information given by the virtual templating seems to be more accurate in the transversal plane than in the sagittal plane.

Can intraoperative radiation dose in percutaneous posterior thoracolumbar internal fixation be reduced by impedancemetry-guided pedicle sighting? A prospective randomized study

INTRODUCTION

Percutaneous spine surgery is on the rise; the main drawback is iterative irradiation of the care team in theater. The aim of the present study was to compare intraoperative radiation dose in percutaneous posterior thoracolumbar internal fixation (PPTLIF) using impedancemetry-guided pedicle sighting by the PediGuard device (SpineGuard®) versus gold-standard free-hand sighting.

MATERIAL AND METHODS

A single-center, single-surgeon continuous prospective randomized study was conducted from September 2017 to April 2018. Dose-area product (DAP, in cGy.cm²) was recorded at the end of pedicle sighting and end of surgery in the free-hand control group and the impedancemetry group. Pedicle screw position was studied on postoperative CT scan.

RESULTS

Sixteen patients were included in either group after 2 had been excluded. The groups were comparable for age, gender, body-mass index (BMI), indication and number of instrumented levels. Mean DPA at end of sighting and end of procedure was respectively 147.4 cGy.cm² and 230.9 cGy.cm² in the control group and 171.1 cGy.cm² and 280.7 cGy.cm² in the PediGuard group (p> 0.05). Screw positioning on CT was comparable in the 2 groups.

CONCLUSION

In the present study, the PediGuard device did not reduce intraoperative radiation dose. The correlation between radiation dose and BMI was confirmed.

LEVEL OF EVIDENCE

II; prospective randomized study.

Design of Proposed Software System for Prediction of Iliosacral Screw Placement for Iliosacral Joint Injuries Based on X-ray and CT Images

One of the crucial tasks for the planning of surgery of the iliosacral joint is placing an iliosacral screw with the goal of fixing broken parts of the pelvis. Tracking of proper screw trajectory is usually done in the preoperative phase by the acquisition of X-ray images under different angles, which guide the surgeons to perform surgery. This approach is standardly complicated due to the investigation of 2D X-ray images not showing spatial perspective. Therefore, in this pilot study, we propose complex software tools which are aimed at making a simulation model of reconstructed CT (DDR) images with a virtual iliosacral screw to guide the surgery process. This pilot study presents the testing for two clinical cases to reveal the initial performance and usability of this software in clinical conditions. This model is consequently used for a multiregional registration with reference intraoperative X-ray images to select the slide from the 3D dataset which best fits with reference X-ray. The proposed software solution utilizes input CT slices of the pelvis area to create a segmentation model of individual bone components. Consequently, a model of an iliosacral screw is inserted into this model. In the next step, we propose the software CT2DDR which makes DDR projections with the iliosacral screw. In the last step, we propose a multimodal registration procedure, which performs registration of a selected number of slices with reference X-ray, and based on the Structural Similarity Index (SSIM) and index of correlation, the procedure finds the best match of DDR with X-ray images. In this pilot study, we also provide a comparative analysis of the computational costs of the multimodal registration upon various numbers of DDR slices to show the complex software performance. The proposed complex model has versatile usage for modeling and surgery planning of the pelvis area in fractures of iliosacral joints.

Does the intraoperative 3D-flat panel control of the planned implant position lead to an optimization and increased in safety in the anatomically demanding region C1/2?

BACKGROUND

The aim of this study was to evaluate the applicability and advantages of intraoperative imaging using a 3D flat panel in the treatment of C1/2 instabilities.

MATERIALS

Prospective single-centered study including surgeries at the upper cervical spine between 06/2016 and 12/2018. Intraoperatively thin K-wires were placed under 2D fluoroscopic control. Then an intraoperative 3D-scan was carried out. The image quality was assessed based on a numeric analogue scale (NAS) from 0 to 10 (0 = worst quality, 10 = perfect quality) and the time for the 3D-scan was measured. Additionally, the wire positions were evaluated regarding malpositions.

RESULTS

A total of 58 patients were included (33f, 25 m, average age 75.2 years, r.:18-95) with pathologies of C2: 45 type II fractures according to Anderson/D'Alonzo with or without arthrosis of C1/2, 2 Unhappy triad of C1/2 (Odontoid fracture Type II, anterior or posterior C1 arch-fracture, Arthrosis C1/2) 4 pathological fractures, 3 pseudarthroses, 3 instabilities of C1/2 because of rheumatoid arthritis, 1 C2 arch fracture). 36 patients were treated from anterior [29 AOTAF (combined anterior odontoid and transarticular C1/2 screw fixation), 6 lag screws, 1 cement augmented lag screw] and 22 patients from posterior (regarding to Goel/Harms). The median image quality was 8.2 (r.: 6-10). In 41 patients (70.7%) the image quality was 8 or higher and in none of the patients below 6. All of those 17 patients the image quality below 8 (NAS 7 = 16; 27.6%, NAS 6 = 1, 1.7%), had dental implants. A total of 148 wires were analyzed. 133 (89.9%) showed a correct positioning. In the other 15 (10.1%) cases a repositioning had to be done (n = 8; 5.4%) or it had to be drawn back (n = 7; 4.7%). A repositioning was possible in all cases. The implementation of an intraoperative 3D-Scan took an average of 267 s (r.: 232-310 s). No technical problems occurred.

CONCLUSION

Intraoperative 3D imaging in the upper cervical spine is fast and easy to perform with sufficient image quality in all patients. Potential malposition of the primary screw canal can be detected by initial wire positioning before the Scan. The intraoperative correction was possible in all patients. Trial registration German Trials Register (Registered 10 August 2021, DRKS00026644-Trial registration: German Trials Register (Registered 10 August 2021, DRKS00026644- https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00026644 ).

Intraoperative revision rates due to three-dimensional imaging in orthopedic trauma surgery: results of a case series of 4721 patients

PURPOSE

Intraoperative 3D imaging has become a valued tool in assessing the quality of reduction and implant placement in orthopedic trauma surgery. In our institution, 3D imaging is used routinely since 2001. To evaluate the intraoperative findings and consequences of this technique, intraoperative revision rates in cases with 3D imaging were analyzed.

METHODS

All operative procedures carried out with intraoperative 3D imaging between August 2001 and December 2016 were included. The scans were assessed intraoperatively and documented thereafter. In case of malreduction or misplaced implants, an immediate revision was performed. The number of scans per case as well as the findings and consequences drawn regarding the anatomical region were analyzed.

RESULTS

4721 cases with 7201 3D scans were included in this study. The most common anatomical regions were the ankle (22.3%), the calcaneus (14.8%) and the tibial head (9.5%). In 19.1% of all cases, an intraoperative revision was performed. The highest revision rates were found with 36.0% in calcaneal fractures, 24.8% in fractures of the tibial plateau, 22.3% in injuries of the ankle. In 52.0% of revisions, the reduction was improved regarding intra-articular steps or joint congruency. In 30.5% an implant was corrected.

CONCLUSION

Intraoperative revision due to results of 3D imaging was performed in almost one-fifth of cases. This illustrates the improved possibilities to detect malreduction and implant misplacements intraoperatively and thus the abilities to improve surgical outcome.

LEVEL OF EVIDENCE

III.

Fluoroscopic imaging: New advances

Today's orthopedic surgery could not be imagined without intraoperative x-ray-based imaging. This enables surgeons to assess operative interim steps as well as the result before wound closure and finishing the procedure. Although there have been mobile C-arms used for decades, there are recent advances that do not only affect the quality of the imaging itself but also the way, the information is processed and presented. These very exciting developments will change the integration of imaging into the surgical workflows, giving options of augmented reality, reduction of radiation dose, automatized acquisition and analysis of images and low-level guidance in procedures. This paper gives a review of current innovations and possible future trends in fluoroscopic 2D and 3D imaging.

X23D-Intraoperative 3D Lumbar Spine Shape Reconstruction Based on Sparse Multi-View X-ray Data

Visual assessment based on intraoperative 2D X-rays remains the predominant aid for intraoperative decision-making, surgical guidance, and error prevention. However, correctly assessing the 3D shape of complex anatomies, such as the spine, based on planar fluoroscopic images remains a challenge even for experienced surgeons. This work proposes a novel deep learning-based method to intraoperatively estimate the 3D shape of patients' lumbar vertebrae directly from sparse, multi-view X-ray data. High-quality and accurate 3D reconstructions were achieved with a learned multi-view stereo machine approach capable of incorporating the X-ray calibration parameters in the neural network. This strategy allowed a priori knowledge of the spinal shape to be acquired while preserving patient specificity and achieving a higher accuracy compared to the state of the art. Our method was trained and evaluated on 17,420 fluoroscopy images that were digitally reconstructed from the public CTSpine1K dataset. As evaluated by unseen data, we achieved an 88% average F1 score and a 71% surface score. Furthermore, by utilizing the calibration parameters of the input X-rays, our method outperformed a counterpart method in the state of the art by 22% in terms of surface score. This increase in accuracy opens new possibilities for surgical navigation and intraoperative decision-making solely based on intraoperative data, especially in surgical applications where the acquisition of 3D image data is not part of the standard clinical workflow.

Surgical outcomes of spinal osteochondroma in children: A multicentre observational study

BACKGROUND

Spinal osteochondroma (or exostosis) is a rare benign tumour whose clinical manifestations are delayed due to their slow growth and location. Few studies have addressed the characteristics and the diagnostic and therapeutic peculiarities of spinal osteochondroma in children. The objective of this multicentre observational study was to assess the outcomes of a cohort of children after surgery for spinal osteochondroma.

HYPOTHESIS

Surgical excision of spinal osteochondroma in children is not followed by complications or recurrences.

MATERIAL AND METHODS

We included consecutive children who had surgery between 2010 and 2018 at any of eight participating centres to remove spinal osteochondromas. The cause, clinical manifestations, and location of the lesions were collected. The surgical outcomes were evaluated after at least 2 years' follow-up.

RESULTS

We identified 22 patients who had surgery to remove 26 spinal osteochondromas at a mean age of 12.8±2.6 years. Among them, 7 had a solitary osteochondroma (SO group) and 15 had hereditary multiple osteochondromas (HMO group). At diagnosis, 72% of patients had clinical signs (spinal pain, n=4; one or more lumps, n=5; and neurological manifestations, n=3). In the HMO group, the diagnosis was made during routine MRI screening for tumours involving the spinal canal. Most osteochondromas involved the cervical spine (n=13), with no difference between the two groups (p=0.9). The lamina was the most common location but 54% of the tumours were growing within the canal (92% in the HMO group). After a mean follow-up of 5.2±4.4 years, no patients had experienced any recurrences or complications related to the disease or treatment.

DISCUSSION

Surgical excision of spinal osteochondromas in children is effective, with no medium-term recurrences. Our results also confirm the low peri-operative morbidity, even when the canal is involved, and the absence of any effect at last follow-up on spinal alignment. All patients with neurological manifestations at diagnosis made a full recovery.

LEVEL OF EVIDENCE

IV, retrospective observational cohort study.

Accuracy and reliability analysis of a machine learning based segmentation tool for intertrochanteric femoral fracture CT

Introduction

Three-dimensional (3D) reconstruction of fracture fragments on hip Computed tomography (CT) may benefit the injury detail evaluation and preoperative planning of the intertrochanteric femoral fracture (IFF). Manually segmentation of bony structures was tedious and time-consuming. The purpose of this study was to propose an artificial intelligence (AI) segmentation tool to achieve semantic segmentation and precise reconstruction of fracture fragments of IFF on hip CTs.

Materials and Methods

A total of 50 labeled CT cases were manually segmented with Slicer 4.11.0. The ratio of training, validation and testing of the 50 labeled dataset was 33:10:7. A simplified V-Net architecture was adopted to build the AI tool named as IFFCT for automatic segmentation of fracture fragments. The Dice score, precision and sensitivity were computed to assess the segmentation performance of IFFCT. The 2D masks of 80 unlabeled CTs segmented by AI tool and human was further assessed to validate the segmentation accuracy. The femoral head diameter (FHD) was measured on 3D models to validate the reliability of 3D reconstruction.

Results

The average Dice score of IFFCT in the local test dataset for “proximal femur”, “fragment” and “distal femur” were 91.62%, 80.42% and 87.05%, respectively. IFFCT showed similar segmentation performance in cross-dataset, and was comparable to that of human expert in human-computer competition with significantly reduced segmentation time (p < 0.01). Significant differences were observed between 2D masks generated from semantic segmentation and conventional threshold-based segmentation (p < 0.01). The average FHD in the automatic segmentation group was 47.5 ± 4.1 mm (41.29∼56.59 mm), and the average FHD in the manual segmentation group was 45.9 ± 6.1 mm (40.34∼64.93 mm). The mean absolute error of FHDs in the two groups were 3.38 mm and 3.52 mm, respectively. No significant differences of FHD measurements were observed between the two groups (p > 0.05). All ICCs were greater than 0.8.

Conclusion

The proposed AI segmentation tool could effectively segment the bony structures from IFF CTs with comparable performance of human experts. The 2D masks and 3D models generated from automatic segmentation were effective and reliable, which could benefit the injury detail evaluation and preoperative planning of IFFs.

Comparison of pedicle screw placement accuracy between two types of imaging support (Artis Zeego versus two-dimensional fluoroscopy): a cross-sectional observational study

Background

The pedicle screw system is widely used in spine surgery, and it provides rigid fixation and leads to successful subsequent deformity correction and bony fusion. The standard imaging technique for pedicle screw insertion is two-dimensional images obtained from C-arm-type X-ray fluoroscopy. Artis Zeego is an emerging intraoperative imaging technique that can provide conventional two-dimensional fluoroscopic images and rapid three-dimensional fluoroscopic computed tomography reconstruction imaging. The aim of this study is to compare the insertion accuracies of PS placement using Artis Zeego and conventional 2D X-ray fluoroscopy.

Methods

In this study, we retrospectively reviewed the postoperative images of thoracolumbar fusion patients who underwent surgery using pedicle screws between 2013 and 2018. Pedicle screw malplacement was assessed using a four-grade classification by Rao et al. Misplacement rates were compared between pedicle screws assisted with Artis Zeego and two-dimensional fluoroscopy.

Results

A total of 1107 pedicle screws in 153 patients were inserted using Artis Zeego, and 427 pedicle screws in 80 patients were inserted using fluoroscopy. The overall perforation rate was 4.2% (46 perforations of 1106 pedicle screws) in the Artis Zeego group and 7.7% (33 perforations of 427 pedicle screws) in the fluoroscopy group. In the Artis Zeego group, 43 (3.9%) screws were classified as grade 1, and three (0.3%) screws were classified as grade 2. In the fluoroscopy group, 21 (4.9%) screws were classified as grade 1, 10 (2.3%) screws were classified as grade 2, and 2 (0.5%) screws were classified as grade 3. The use of Artis Zeego was associated with a significantly lower screw malplacement rate than was the use of fluoroscopy (p < 0.001).

Conclusions

Our results demonstrated that pedicle screw placement with Artis Zeego was associated with a lower malplacement rate than was conventional two-dimensional fluoroscopy. No severe malplacement was observed in the Artis Zeego group. Thus, Artis Zeego could be a good option for improving pedicle screw accuracy.

Deformable 3D-2D image registration and analysis of global spinal alignment in long-length intraoperative spine imaging

BACKGROUND

Spinal deformation during surgical intervention (caused by patient positioning and/or correction of malalignment) confounds conventional navigation due to assumptions of rigid transformation. Moreover, the ability to accurately quantify spinal alignment in the operating room would provide assessment of the surgical product via metrics that correlate with clinical outcome.

PURPOSE

A method for deformable 3D-2D registration of preoperative CT to intraoperative long-length tomosynthesis images is reported for accurate 3D evaluation of device placement in the presence of spinal deformation and automated evaluation of global spinal alignment (GSA).

METHODS

Long-length tomosynthesis ("Long Film", LF) images were acquired using an O-arm™ imaging system (Medtronic, Minneapolis USA). A deformable 3D-2D patient registration was developed using multi-scale masking (proceeding from the full-length image to local subvolumes about each vertebra) to transform vertebral labels and planning information from preoperative CT to the LF images. Automatic measurement of GSA [Main Thoracic Kyphosis (MThK) and Lumbar Lordosis (LL)] was obtained using a spline fit to registered labels. The "Known-Component Registration" (KC-Reg) method for device registration was adapted to the multi-scale process for 3D device localization from orthogonal LF images. The multi-scale framework was evaluated using a deformable spine phantom in which pedicle screws were inserted, and deformations were induced over a range in LL ∼25-80°. Further validation was carried out in a cadaver study with implanted pedicle screws and a similar range of spinal deformation. The accuracy of patient and device registration was evaluated in terms of 3D translational error and target registration error (TRE), respectively, and the accuracy of automatic GSA measurements were compared to manual annotation.

RESULTS

Phantom studies demonstrated accurate registration via the multi-scale framework for all vertebral levels in both the neutral and deformed spine: median (interquartile range, IQR) patient registration error was 1.1 mm (0.7-1.9 mm IQR). Automatic measures of MThK and LL agreed with manual delineation within -1.1° ± 2.2° and 0.7° ± 2.0° (mean and standard deviation), respectively. Device registration error was 0.7 mm (0.4-1.0 mm IQR) at the screw tip and 0.9° (1.0°-1.5°) about the screw trajectory. Deformable 3D-2D registration significantly outperformed conventional rigid registration (p < 0.05), which exhibited device registration error of 2.1 mm (0.8-4.1 mm) and 4.1° (1.2°-9.5°). Cadaver studies verified performance under realistic conditions, demonstrating patient registration error of 1.6 mm (0.9-2.1 mm); MThK within -4.2° ± 6.8° and LL within 1.7° ± 3.5°; and device registration error of 0.8 mm (0.5-1.9 mm) and 0.7° (0.4°-1.2°) for the multi-scale deformable method, compared to 2.5 mm (1.0-7.9 mm) and 2.3° (1.6°-8.1°) for rigid registration (p < 0.05).

CONCLUSION

The deformable 3D-2D registration framework leverages long-length intraoperative imaging to achieve accurate patient and device registration over extended lengths of the spine (up to 64 cm) even with strong anatomical deformation. The method offers a new means for quantitative validation of spinal correction (intraoperative GSA measurement) and 3D verification of device placement in comparison to preoperative images and planning data. This article is protected by copyright. All rights reserved.

Augmented Reality in Orthopedic Surgery and Its Application in Total Joint Arthroplasty: A Systematic Review

The development of augmented reality (AR) and its application in total joint arthroplasty aims at improving the accuracy and precision in implant components’ positioning, hopefully leading to increased outcomes and survivorship. However, this field is far from being thoroughly explored. We therefore performed a systematic review of the literature in order to examine the application, the results, and the different AR systems available in TJA. A systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. A comprehensive search of PubMed, MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews was conducted for English articles on the application of augmented reality in total joint arthroplasty using various combinations of keywords since the inception of the database to 31 March 2022. Accuracy was intended as the mean error from the targeted positioning angle and compared as mean values and standard deviations. In all, 14 articles met the inclusion criteria. Among them, four studies reported on the application of AR in total knee arthroplasty, six studies on total hip arthroplasty, three studies reported on reverse shoulder arthroplasty, and one study on total elbow arthroplasty. Nine of the included studies were preclinical (sawbones or cadaveric), while five of them reported results of AR’s clinical application. The main common feature was the high accuracy and precision when implant positioning was compared with preoperative targeted angles with errors ≤2 mm and/or ≤2°. Despite the promising results in terms of increased accuracy and precision, this technology is far from being widely adopted in daily clinical practice. However, the recent exponential growth in machine learning techniques and technologies may eventually lead to the resolution of the ongoing limitations including depth perception and their high complexity, favorably encouraging the widespread usage of AR systems.

Screw misplacement in percutaneous posterior pelvic iliosacral screwing with and without navigation: A prospective clinical study of 174 screws in 127 patients

BACKGROUND

Recent studies of iliosacral screw fixation performed using intraoperative navigation systems have shown promising results. The Surgivisio Platform is a new-generation three-dimensional intraoperative navigation tool that has been used at our institution for 2years. The aim of this prospective study was to assess the contribution of navigation in terms of iliosacral screw positioning accuracy and of radiation exposure, by comparing outcomes with vs. without navigation.

HYPOTHESIS

Navigation allows more accurate percutaneous iliosacral screw positioning regardless of the type of screw fixation (with sacral dysmorphism and/or cemented screw fixation and/or multiple screw fixation).

MATERIALS AND METHODS

Between January 2018 and December 2019, consecutive patients who underwent percutaneous iliosacral screw fixation of pelvic ring fractures without vertical instability were included in this single-centre prospective study. Screw position accuracy was evaluated by postoperative high-resolution computed tomography (HRCT). Operative time, radiation dose, and complications were recorded.

RESULTS

We included 127 patients with 174 iliosacral screws, of which 129 were positioned under fluoroscopic guidance and 45 using navigation. According to the modified Gras classification, 7% (12/174) of the screws were incorrectly positioned and 2% (4/174) required repositioning. The frequency of screw malposition was not significantly different between the fluoroscopy and navigation groups (8.5%, 11/129 vs. 2.2%, 1/45, respectively; p=0.19). However, screw position in dysmorphic sacra was significantly better with navigation (p=0.04), whereas no significant difference in final screw position was found for cemented or multiple screw implantations. In the navigation group, the operative time was significantly longer (28.2min vs. 21.6min, p=0.003), and the mean dose-area product significantly greater (6.6Gy·cm² vs. 4.9Gy·cm², p=0.02). The complication rates were not different between the two groups.

CONCLUSION

In patients who have pelvic ring fractures without vertical instability, navigation of percutaneous iliosacral screw placement using the Surgivisio Platform improves screw positioning in dysmorphic sacra, at the cost of a longer operative time and greater radiation exposure of the patient.

LEVEL OF EVIDENCE

II, prospective study.

Differences in Accuracy and Radiation Dose in Placement of Iliosacral Screws: Comparison between 3D and 2D Fluoroscopy

Percutaneous iliosacral screw fixation is a widely accepted method of stabilizing the posterior pelvic ring. Recently developed tools such as 3D-navigated fluoroscopy and computed navigation seem to prevent a surgeon from conducting screw misplacement. The study aimed to comparatively assess the introduction of sacroiliac screw placement using 2D and 3D fluoroscopy in terms of accuracy and radiation exposure. Iliosacral screws were introduced in 37 patients using 2D (group N1) and in 36 patients using 3D fluoroscopy (group N2) techniques. Overall, 61 and 56 screws were introduced in groups N1 and N2, respectively. Screw placement accuracy was assessed using postoperative computed tomography and Smith’s scale. Intraoperative radiation exposure was also assessed. No differences were noted between groups in terms of screw positioning accuracy and radiation dose. Both 2D and 3D fluoroscopy provide good visualization for safely placing percutaneous iliosacral joint screws. Using 3D fluoroscopy-based navigation in comparison with 2D fluoroscopy is not advantageous.

Automatic Registration and Error Color Maps to Improve Accuracy for Navigated Bone Tumor Surgery Using Intraoperative Cone-Beam CT

Computer-assisted surgery (CAS) can improve surgical precision in orthopaedic oncology. Accurate alignment of the patient’s imaging coordinates with the anatomy, known as registration, is one of the most challenging aspects of CAS and can be associated with substantial error. Using intraoperative, on-the-table, cone-beam computed tomography (CBCT), we performed a pilot clinical study to validate a method for automatic intraoperative registration.

Does intraoperative 3D navigation improve SpineJack vertebral augmentation in thoracic and lumbar compression fracture?

INTRODUCTION

The aim of this retrospective study was to evaluate the effect of navigation on the positioning of the SpineJack implant in the treatment of thoracic and lumbar compression fractures.

METHODS

Between January 2018 and December 2019, all patients operated on for thoracic or lumbar fracture using the SpineJack device in stand-alone were included in this single-center study. The positioning of the SpineJack implant was analyzed on axial CT views by measuring the angle between the axis of the pedicle and the axis of the final implant. The relationships between implant positioning and the use of navigation or fluoroscopy, pedicle dimensions and levels of injury were analyzed. Surgical time, radiation exposure, radiological findings and complications were assessed.

RESULTS

One hundred patients were included, for 103 fractured vertebrae and a total of 205 implants, 148 placed under standard fluoroscopy and 57 with the Surgivisio navigation system. For pedicle diameters≥5mm (165 implants), the positioning of the implant relative to the axis of the pedicle was significantly better in the navigation group: 2°±1.4° (range, 0-7°) in the fluoroscopy group versus 1.2°±1.1° (range, 0-5°) in the navigation group (p=0.04). There were no significant differences in reduction of vertebral kyphosis angle or mean operating time. Dose area product (DAP) was significantly higher with navigation: 4.43Gy.cm² versus 0.47Gy.cm² (p<0.001) and dose to the surgeon significantly lower: 0.5 versus 1.6μSv (p<0.001). No difference was found regarding complications. Subgroup analysis showed significantly greater operative time and patient irradiation in the fluoroscopy group when pedicle diameter was less than 5mm.

CONCLUSION

This study demonstrates the interest of navigation for positioning the SpineJack implant with respect to the pedicle axis in vertebrae with pedicle diameter≥5mm. This study also confirmed the reliability of navigation and lower radiation dose to the surgeon, regardless of the fracture level. Navigation reduced operating time and patient irradiation for vertebrae with pedicle diameter<5mm.

LEVEL OF EVIDENCE

IV; retrospective study.

Assessment of some factors of cellular and humoral immunity in radiology workers

Radiation workers in medical diagnostic departments are occupationally exposed to long-term low-dose ionizing radiation, which may cause radiation-induced side effects. This study investigated subtypes of peripheral blood lymphocytes and immunoglobulin levels in workers who were occupationally exposed to X-ray radiation at the Department of Radiology. Seventeen radiology workers received low levels of ionizing radiation as the study group and 18 individuals who were not exposed to radiation were included as the control group. The percentage of lymphocyte subtypes (CD4⁺, CD8⁺ and CD4⁺/CD8⁺) and serum levels of immunoglobulins (IgA, IgG and IgM) were measured using peripheral blood samples. Considering all lymphocyte subtypes and serum levels of IgA, IgG and IgM, there was no significant difference between the study and control groups (P > 0.05). There were no significant differences in all mentioned parameters regarding gender (P > 0.05). For the length of employment period, there was a significant difference concerning CD4⁺/CD8⁺ (P < 0.05). The findings showed that exposure to low levels of ionizing radiation does not affect the immune system of workers in diagnostic radiology dose level. Because of relatively small samples of workers, it is suggested that these factors be investigated on larger samples of radiology workers.

Utility of 3-Dimensional Intraoperative Imaging in Pelvic and Acetabular Fractures: A Network Meta-Analysis

BACKGROUND

Successful surgical management of pelvic ring and acetabular fractures requires technical expertise to achieve an accurate reduction and stable fixation. The use of 3-dimensional (3D) intraoperative imaging (3DIOI) as an assessment tool has led to improved reduction and placement of implants. The purpose of this study was to assess the utility of using 3DIOI in the management of acetabular and pelvic fractures on the basis of outcomes reported in the literature.

METHODS

A literature search was performed using PubMed, the Cochrane Database of Systematic Reviews (CDSR), and Google Scholar using key terms. A network meta-analysis conducted using the frequentist approach allowed for statistical analysis of reported outcomes regarding screw position (in mm), fracture reduction (in mm), and complications.

RESULTS

A total of 9 studies were included in this analysis. When compared with conventional radiography, the mean radiation dose (in cGy·cm2) was significantly higher in 3DIOI (mean difference, 82.72; 95% confidence interval [CI], 21.83 to 143.61; p = 0.007). Use of 3DIOI yielded a 93% lower risk of developing medical complications (odds ratio [OR], 0.07; 95% CI, 0.02 to 0.35; p = 0.014). Use of 3DIOI yielded higher odds of achieving accurate screw placement (OR, 4.21; 95% CI, 1.44 to 12.32; p = 0.008) and perfect reduction (OR, 2.60; 95% CI, 1.19 to 5.68; p = 0.016). In ranking the imaging modalities, 12 of the 13 parameters analyzed were in favor of 3DIOI over conventional fluoroscopy and 2D navigation imaging.

CONCLUSIONS

Current literature supports the use of 3DIOI because of the decreased rates of misplaced implants, malreduced fractures, complications, and subsequent revision operations. The use of 3DIOI allows for improved visualization of pelvic anatomy when repairing pelvic and acetabular fractures, and helps surgeons to achieve favorable surgical outcomes.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Surgivisio® and O-arm®O2 cone beam CT mobile systems for guidance of lumbar spine surgery: Comparison of patient radiation dose

PURPOSE

To compare patient radiation doses in cone beam computed tomography (CBCT) of two mobile systems used for navigation-assisted mini-invasive orthopedic surgery: O-arm®O2 and Surgivisio®.

METHODS

The study focused on imaging of the spine. Thermoluminescent dosimeters were used to measure organs and effective doses (ED) during CBCT. An ionization-chamber and a solid-state sensor were used to measure the incident air-kerma (K_i) at the center of the CBCT field-of-view and K_i during 2D-imaging, respectively. The PCXMC software was used to calculate patient ED in 2D and CBCT configurations. The image quality in CBCT was evaluated with the CATPHAN phantom.

RESULTS

The experimental ED estimate for the low-dose 3D-modes was 2.41 and 0.35 mSv with O-arm®O2 (Low Dose 3D-small-abdomen) and Surgivisio® (3DSU-91 images), respectively. PCXMC results were consistent: 1.54 and 0.30 mSv. Organ doses were 5 to 12 times lower with Surgivisio®. K_i at patient skin were comparable on lateral 2D-imaging (0.5 mGy), but lower with O-arm®O2 on anteroposterior (0.3 versus 0.9 mGy). Both systems show poor low contrast resolution and similar high contrast spatial resolution (7 line-pairs/cm).

CONCLUSIONS

This study is the first to evaluate patient ED and organ doses with Surgivisio®. A significant difference in organs doses was observed between the CBCT systems. The study demonstrates that Surgivisio® used on spine delivers approximately five to six times less patient ED, compared to O-arm®O2, in low dose 3D-modes. Doses in 2D-mode preceding CBCT were higher with Surgivisio®, but negligible compared to CBCT doses under the experimental conditions tested.

Clinical impact of intraoperative cone beam tomography and navigation for displaced acetabular fractures: a comparative study at medium-term follow-up

INTRODUCTION

The use of per-operative cone beam tomography imaging for displaced acetabular fractures yields increased post-operative articular reduction accuracy. This study evaluates the need for total hip replacement (THR) and hip-related functional outcomes in patients with displaced acetabular fractures treated with O-ARM guidance compared to those treated under C-ARM guidance.

MATERIALS AND METHODS

This is a prospective matched cohort study. Adult patients (35) with acetabular fractures operated under O-ARM guidance were included. These were matched (age, fracture type) to classically treated patients (35) from our data base. The primary outcome was the need for THR during three year follow-up period. Secondary outcomes were functional scores [Harris Hip score (HHS), Postel-Merle d'Aubigné (PMA)] and hip osteoarthritis grade at three year follow-up. Correlation between reduction gap and THR was evaluated.

RESULTS

At three years, five patients were lost to follow-up in O-ARM group and four in control group. Two patients (6.66%) in the O-ARM group needed THR compared to eight patients in controls (25.80%) (p = 0.046). Hip X-ray osteoarthritis grade averaged 0.00 in patients without THR in O-ARM group compared to 0.22 in patients without THR in controls (p = 0.008). HHS averaged 95.79 in patients without THR in O-ARM group, compared to 93.82 in patients without THR in the control group (p = 0.41%). PMA averaged 17.25 in patients without THR in the O-ARM group compared to 17.04 in patients without THR in group 2 (p = 0.37). Evaluation of correlation between reduction gap and THR rate yielded OR = 1.22 (1.06-1.45).

DISCUSSION

Increased accuracy in articular reduction, with per-operative three-dimensional control of impaction, in acetabular fractures led to significantly less need for THR in patients treated under O-ARM. Patients in both groups are comparable for functional outcomes because those with the lowest scores were offered THR. Per-operative cone beam guidance and navigation use are recommended in tertiary referral centres for acetabular trauma.

Navigated total knee arthroplasty: Retrospective study of 600 continuous cases

INTRODUCTION

Computer-assisted navigation in total knee arthroplasty (TKA) has existed for more than 20 years, although its use has been marginal. Its benefits are still largely debated, especially its efficacy for achieving the desired postoperative alignment.

HYPOTHESIS

A neutral hip-knee-ankle (HKA) angle (180°±3°) will be achieved in at least 85% of cases and there will be no difference between the different types of navigation systems used.

MATERIAL AND METHODS

In this retrospective, single-center, single-surgeon study, all the TKAs completed between September 2003 and December 2017 were included, giving a total of 753 navigated TKAs: Navitrack group: 196 Natural Knee II implants (Zimmer) with the Navitrack-OS Knee system (Zimmer CAS); Brainlab group: 557 implants (196 Profix, Smith & Nephew and 361 LCS, DePuy) with the Brainlab Vector Vision system. The aim of navigation was independent of the preoperative alignment and was always to achieve a neutral HKA mechanical axis (180°±3°). The primary endpoint was the postoperative HKA angle. This parameter was used to determine whether the navigation objective was achieved, to define how many patients were outliers and to compare navigation systems to each other. The potential influence of sex, body mass index (BMI) and preoperative deformity were secondary aims. Lastly, the final navigation values were compared to radiological data to detect any potential deviations.

RESULTS

We analyzed 600 of the cases, 160 in the Navitrack group and 440 in the Brainlab group (152 Profix and 288 LCS). A neutral HKA angle was found in 91% patients: 93% for the Navitrack group and 90% in the Brainlab group (90.8% Profix and 89.6% LCS). There was no significant difference between groups (p=0.68), nor between subgroups (p=0.85). An elevated BMI negatively influenced the ability to achieve a neutral HKA (p=0.015), regardless of the system used.

CONCLUSION

In our study of 600 TKA cases done with navigation, the postoperative alignment goal (HKA 180°±3°) was achieved in 91% of cases. There was no difference between navigation systems. Patients with a high BMI were more likely to be outliers (p=0.015).

LEVEL OF EVIDENCE

IV.

Influence of antibiotic pellets on pore size and shear stress resistance of impacted native and thermodisinfected cancellous bone: An in vitro femoral impaction bone grafting model

Introduction

Morphology and mechanic properties of impacted cancellous bone are affected by carrier substances which provide high local concentrations of antibiotics.

Methods

Bone chips were taken from the femoral head of 6-7 months old piglets. One half was thermodisinfected and the other remained native. Ten specimens each were mixed with Herafill® antibiotic pellets and a control group of each 10 specimens respectively was examined. The cancellous bone was impacted according to Exeter technique and the implants were cemented. The distribution of the particles and the pores were defined with three dimensional computertomographic scan and shear force resistance was measured until failure.

Results

Shear force resistance was not measured significantly less for thermodisinfected (2.7 Nm) compared with native bone (3.5 Nm) and addition of antibiotic pellets reduced shear force resistance in both groups since this was significant for the native group. The average pore volume of the native bone specimens appeared significant smaller compared to the thermodisinfected group (p = 0.011) and the pore volume showed a negative correlation with shear force resistance (p = 0.044). Pore volume around the pellets was found significantly increased and it appeared smaller for native bone. The number of pellets located next to the implant showed a negative correlation with shear force resistance (p = 0.034) and the negative correlation increased for pellets below the tip of the shaft model (p = 0.024).

Conclusion

Adding antibiotic pellets to native and thermodisinfected impacted cancellous bone increased pore volume since the area around the pellets showed increased porosity which correlated with reduced shear force resistance. Computertomographic three dimensional measurement of porosity might predict shear force resistance of impacted cancellous bone and improve impaction of bone grafting intraoperatively.

Irradiation level related to intraoperative imaging device in paediatric elastic stable intramedullary nailing: preliminary prospective study on 51 patients using PCXMC software

PURPOSE

Radiation-induced cancers due to imaging devices concern above all the growing child, however, to date, intraoperative irradiation doses are not well-documented in children. The goal of the study was to evaluate the intraoperative doses received by patients operated with the use of a C-arm in traumatology, as well as the lifetime attributable risk of cancer death (LAR) related to the irradiation of the imaging device.

METHODS

From 1 April 2017 to 31 March 2019, we started a multicentre study and prospectively recruited all consecutive children who needed elastic stable intramedullary nailing (ESIN) for long-bone fracture. We collected demographic and operative data, with dose reports including duration and doses. The main outcome was the effective dose (ED) in millisievert (mSv), calculated with PCXMC software, and the secondary outcome was the LAR expressed as a percentage.

RESULTS

In all, 51 patients operated on using 2D C-arm imaging were included in this study. The mean ED was 0.085 mSv (sd 0.10; 0.002 to 0.649). Overall LAR was 6.5 x 10^-4% (sd 6.7 x 10^-4%; 0.1 x 10^-4% to 28.3x10^-4%). Univariate linear regression showed a significant association between ED and irradiation time (p < 0.001). There was no significant association between ED and other outcomes (p > 0.05).

CONCLUSION

Treatment of long-bone fractures by ESIN found a low level of effective doses with utilization of the C-arm device in current practice. Further studies on a larger sample are needed to confirm these results.

LEVEL OF EVIDENCE

II.