Radiation dose reduction in thoracic and lumbar spine instrumentation using navigation based on an intraoperative cone beam CT imaging system: a prospective randomized clinical trial

Clinical Application and Curative Effect Analysis of Postural Awareness Surgical Tool Assisted Nail Placement in Adolescent Idiopathic Scoliosis

OBJECTIVE

The pedicle screw technique has been widely used in adolescent idiopathic scoliosis orthopedic surgery, but misplacement of screws may damage important structures such as blood vessels and nerves around the pedicle, resulting in serious consequences. Therefore, our research team has independently developed a surgical tool to assist in the placement of pedicle screws. This study aims to investigate the safety and accuracy of postural awareness tool assisted nail placement in orthopedic surgery for adolescent idiopathic scoliosis.

METHOD

A retrospective analysis was performed on 24 adolescent patients with idiopathic scoliosis admitted to our hospital from July 2019 to July 2022, including 10 males and 14 females, with an average age of 14.88 ± 2.36 years (10-19 years). The mean follow-up was 15.67 ± 2.20 months (12-20 months). We divided the patients into postural awareness group (n = 12) and C-arm group (n = 12) according to whether the postural awareness surgical tool was used during the operation. All patients were treated with posterior spinal orthopedic surgery. The postural awareness group was assisted by pedicle screw placement with a postural awareness surgical tool, while the C-arm group was given a pedicle screw placement with freehand technique. The operative time, intraoperative blood loss, intraoperative fluoroscopy times, nail placement related complications, nail placement accuracy, and scoliosis correction rate were recorded and compared between the two groups.

RESULTS

The operative time, intraoperative blood loss and fluoroscopy times in the postural awareness group were significantly lower than those in the C-arm group, with statistical significance (p < 0.05). The postural awareness group implanted 163 screws with an accuracy rate of 91.41%, while the C-arm group implanted 159 screws with an accuracy rate of 83.02%. The accuracy rate of screw placement in the postural awareness group was higher than that in the C-arm group, with a statistically significant difference (p = 0.024). According to the imaging of the patients, there was no significant difference between the Cobb Angle of the main bend measured at three time points before surgery, 1 week after surgery and the last follow-up between the two groups. Similarly, there was no significant difference in the rate of lateral curvature correction between the two groups.

CONCLUSION

The application of postural awareness surgical tool in posterior orthopedic surgery for adolescent idiopathic scoliosis can improve screw placement accuracy, shorten screw placement time, and make auxiliary screw placement safer and more accurate.

[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.

The use of hybrid operating rooms in neurosurgery, advantages, disadvantages, and future perspectives: a systematic review

BACKGROUND

Hybrid operating rooms (hybrid-ORs) combine the functionalities of a conventional surgical theater with the advanced imaging technologies of a radiological suite. Hybrid-ORs are usually equipped with CBCT devices providing both 2D and 3D imaging capability that can be used for both interventional radiology and image guided surgical applications. Across all fields of surgery, the use of hybrid-ORs is gaining in traction, and neurosurgery is no exception. We hence aimed to comprehensively review the use of hybrid-ORs, the associated advantages, and disadvantages specific to the field of neurosurgery.

MATERIALS AND METHODS

Electronic databases were searched for all studies on hybrid-ORs from inception to May 2022. Findings of matching studies were pooled to strengthen the current body of evidence.

RESULTS

Seventy-four studies were included in this review. Hybrid-ORs were mainly used in endovascular surgery (n = 41) and spine surgery (n = 33). Navigation systems were the most common additional technology employed along with the CBCT systems in the hybrid-ORs. Reported advantages of hybrid-ORs included immediate assessment of outcomes, reduced surgical revision rate, and the ability to perform combined open and endovascular procedures, among others. Concerns about increased radiation exposure and procedural time were some of the limitations mentioned.

CONCLUSION

In the field of neurosurgery, the use of hybrid-ORs for different applications is increasing. Hybrid-ORs provide preprocedure, intraprocedure, and end-of-procedure imaging capabilities, thereby increasing surgical precision, and reducing the need for postoperative imaging and correction surgeries. Despite these advantages, radiation exposure to patient and staff is an important concern.

Intraoperative Cone Beam CT in Hybrid Operation Room for Pediatric Scoliosis Patients: Comparison of Pedicle Screw Violation Rate at Normal and Low Radiation Doses

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

This study aimed to determine the effect of reducing the radiation dose of intraoperative cone beam computed tomography (CBCT) during posterior spinal fusion (PSF) for pediatric scoliosis on the rate of pedicle screw (PS) violation.

SUMMARY OF BACKGROUND DATA

Intraoperative CBCT for pediatric scoliosis improves the accuracy of PS insertion in PSF. However, few reports have addressed the PS perforation rate from reduced radiation doses in hybrid navigation.

METHODS

We evaluated 855 PSs inserted into 58 pediatric scoliosis patients (11 male and 47 female, mean age: 16.6 yr) who underwent PSF using CBCT. A radiation dose of 1/3 or 1/5 of the normal dose (ND) was defined as a low dose (LD). After PS insertion, intraoperative CBCT images were reviewed to assess the degree of PS perforation. G2-3 (i.e., perforations of 4 mm or more) was defined as a violation. The PS violation rate was compared between the groups, and factors associated with violations were examined.

RESULTS

A total of 567 and 288 screws were inserted in the ND group and LD group, respectively. The PS violation rate was comparable at 1.8% in the ND group and 1.7% in the LD group. Multiple logistic regression analysis showed that distance from the upper instrumented vertebra (UIV) was an independently associated factor of PS violation (+1 vertebra, operation room 0.73, P   =  0.038). In addition, the mean height of patients with PS violations (148.8 ± 3.6 cm) was significantly shorter than that of patients without violations (157.9 ± 1.2 cm) ( P  = 0.034).

CONCLUSION

There was no increase in PS violation rate with lower doses of radiation for intraoperative navigation CBCT. Extra care is warranted for vertebrae close to the UIV and patients of shorter stature.Level of Evidence: 3.

Comparison of differences and random errors in pedicle diameter measurements between MRI and CT: observational study of 315 pedicles in Lenke type 1 adolescent idiopathic scoliosis patients

BACKGROUND CONTEXT

Posterior spinal fusion with pedicle screws is commonly used for the treatment of adolescent idiopathic scoliosis (AIS). To reduce radiation exposure, methods other than computed tomography (CT) are desirable for preoperative determination of pedicle diameter.

PURPOSE

Investigate the differences between magnetic resonance imaging (MRI) and CT measurements of pedicle diameter.

STUDY DESIGN

Cross-sectional research.

PATIENT SAMPLE

Twenty-one AIS Lenke type 1 patients (19 female and 2 males, mean age at surgery: 15.4 years) who underwent posterior spinal fusion between April 2009 and October 2019.

OUTCOME MEASURES

Gap between CT and MRI pedicle diameters.

METHODS

The inner and outer diameters of the right and left pedicles from T1 to L3 were measured separately by two spine surgeons for statistical comparisons.

RESULTS

The respective minimum and maximum CT-MRI values were -3.7 mm and 4.7 mm for inner diameter and -4.6 mm and 5.3 mm for outer diameter. Regarding inter-examiner error, the probability of a 2 mm difference in measurement was less than 5% for both modalities. The probability of a 1 mm difference was also less than 5%, and that of a 3 mm or more difference was 2.1% for the inner diameter and 2.9% for the outer diameter. Whereas low body weight was significantly associated with measurement differences, pedicle laterality was not.

CONCLUSIONS

MRI does not have the reliability to measure pedicle size in AIS patients at present. However, with advancements in image processing technology, the accuracy of pedicle size measurement by MRI may soon improve.

A Modified Endoscopic Transforaminal Lumbar Interbody Fusion Technique: Preliminary Clinical Results of 96 Cases

Background: As a newly emerging technique, endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) has become an increasingly popular procedure of interest. The purpose of this study was to introduce a modified Endo-TLIF system and share our preliminary clinical experiences and outcomes in treating lumbar degenerative disease with this procedure.

Methods: Ninety-six patients (thirty-seven men and fifty-nine women; mean age 55.85 ± 11.03 years) with lumbar degenerative diseases who underwent Endo-TLIF in our hospital were enrolled. The surgical time, volume of intraoperative blood loss, postoperative hospitalization time and postoperative drainage were documented. Clinical outcomes were evaluated by visual analog scale (VAS) scores, Oswestry Disability Index (ODI) scores, and modified MacNab criteria. Bone fusion was identified through computerized tomography (CT) scans or X-ray during the follow-up period.

Results: All patients were followed up for at least 12 months, and the average follow-up time was 17.03 ± 3.27 months. The mean operative time was 136.79 ± 30.14 minutes, and the mean intraoperative blood loss was 53.06 ± 28.89 ml. The mean VAS scores of low back pain and leg pain were 5.05 ± 1.37 and 6.25 ± 1.03, respectively, before surgery, which improved to 2.27 ± 0.66 and 2.22 ± 0.55, respectively, after the operation (P < 0.05). The final VAS scores of low back pain and leg pain were 0.66 ± 0.60 and 0.73 ± 0.66, respectively (P < 0.05). The preoperative ODI score (49.06 ± 6.66) also improved significantly at the 3-month follow-up (13.00 ± 7.37; P < 0.05). The final ODI score was 8.03 ± 6.13 (P < 0.05). There were 10 cases of non-fusion (nine women and one man) at the 12-month follow-up, but no cases of non-union were identified by imaging at the final follow-up.

Conclusions: The present study demonstrated satisfactory clinical and radiologic results among patients who received Endo-TLIF treatment from our institution. This indicates that Endo-TLIF is efficient and safe for select patients.

The Clinical Impact of Image Guidance and Robotics in Spinal Surgery: A Review of Safety, Accuracy, Efficiency, and Complication Reduction

Image guidance (IG) and robotic-assisted (RA) surgery are modern technological advancements that have provided novel ways to perform precise and accurate spinal surgery. These innovations supply real-time, three-dimensional imaging information to aid in instrumentation, decompression, and implant placement. Although nothing can replace the knowledge and expertise of an experienced spine surgeon, these platforms do have the potential to supplement the individual surgeon's capabilities. Specific advantages include more precise pedicle screw placement, minimally invasive surgery with less reliance on intraoperative fluoroscopy, and lower radiation exposure to the surgeon and staff. As these technologies have become more widely adopted over the years, novel uses such as tumor resection have been explored. Disadvantages include the cost of implementing IG and robotics platforms, the initial learning curve for both the surgeon and the staff, and increased patient radiation exposure in scoliosis surgery. Also, given the relatively recent transition of many procedures from inpatient settings to ambulatory surgery centers, access to current devices may be cost prohibitive and not as readily available at some centers. Regarding patient-related outcomes, much further research is warranted. The short-term benefits of minimally invasive surgery often bolster the perioperative and early postoperative outcomes in many retrospective studies on IG and RA surgery. Randomized controlled trials limiting such confounding factors are warranted to definitively show potential independent improvements in patient-related outcomes specifically attributable to IG and RA alone. Nonetheless, irrespective of these current unknowns, it is clear that these technologies have changed the field and the practice of spine surgery. Surgeons should be familiar with the potential benefits and tradeoffs of these platforms when considering adopting IG and robotics in their practices.

Cone-beam imaging with tilted rotation axis: Method and performance evaluation

PURPOSE

The recently introduced robotic x-ray systems provide the flexibility to acquire cone-beam computed tomography (CBCT) data using customized, application-specific source-detector trajectories. We exploit this capability to mitigate the effects of x-ray scatter and noise in CBCT imaging of weight-bearing foot and cervical spine (C-spine) using scan orbits with a tilted rotation axis.

METHODS

We used an advanced CBCT simulator implementing accurate models of x-ray scatter, primary attenuation, and noise to investigate the effects of the orbital tilt angle in upright foot and C-spine imaging. The system model was parameterized using a laboratory version of a three-dimensional (3D) robotic x-ray system (Multitom RAX, Siemens Healthineers). We considered a generalized tilted axis scan configuration, where the detector remained parallel to patient's long body axis during the acquisition, but the elevation of source and detector was changing. A modified Feldkamp-Davis-Kress (FDK) algorithm was developed for reconstruction in this configuration, which departs from the FDK assumption of a detector that is perpendicular to the scan plane. The simulated foot scans involved source-detector distance (SDD) of 1386 mm, orbital tilt angles ranging 10° to 40°, and 400 views at 1 mAs/view and 0.5° increment; the C-spine scans involved -25° to -45° tilt angles, SDD of 1090 mm, and 202 views at 1.3 mAs and 1° increment The imaging performance was assessed by projection-domain measurements of the scatter-to-primary ratio (SPR) and by reconstruction-domain measurements of contrast, noise and generalized contrast-to-noise ratio (gCNR, accounting for both image noise and background nonuniformity) of the metatarsals (foot imaging) and cervical vertebrae (spine imaging). The effects of scatter correction were also compared for horizontal and tilted scans using an ideal Monte Carlo (MC)-based scatter correction and a frame-by-frame mean scatter correction.

RESULTS

The proposed modified FDK, involving projection resampling, mitigated streak artifacts caused by the misalignment between the filtering direction and the detector rows. For foot imaging (no grids), an optimized 20° tilted orbit reduced the maximum SPR from ~1.5 in a horizontal scan to <0.5. The gCNR of the second metatarsal was enhanced twofold compared to a horizontal orbit. For the C-spine (with vertical grids), imaging with a tilted orbit avoided highly attenuating x-ray paths through the lower cervical vertebrae and shoulders. A -35° tilted orbit yielded improved image quality and visualization of the lower cervical spine: the SPR of lower cervical vertebrae was reduced from ~10 (horizontal orbit) to <6 (tilted orbit), and the gCNR for C5-C7 increased by a factor of 2. Furthermore, tilted orbits showed potential benefits over horizontal orbits by enabling scatter correction with a simple frame-by-frame mean correction without substantial increase in noise-induced artifacts after the correction.

CONCLUSIONS

Tilted scan trajectories, enabled by the emerging robotic x-ray system technology, were optimized for CBCT imaging of foot and cervical spine using an advanced simulation framework. The results demonstrated the potential advantages of tilted axis orbits in mitigation of scatter artifacts and improving contrast-to-noise ratio in CBCT reconstructions.

A review of computer-assisted orthopaedic surgery systems

BACKGROUND

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

METHODS

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

RESULTS AND DISCUSSION

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

CONCLUSION

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

The evolution of interlaminar endoscopic spine surgery

Due to the aging population, patients required spinal surgery for degenerative spondylopathy is increasing. With the advent of surgical instruments and techniques, minimally invasive spine surgery is prevalent worldwide. Besides microscopic techniques, endoscopic spine surgery has gotten attention gradually in this surgical field for the past two decades. There are two essential approaches developed currently, including transforaminal and interlaminar approach. These innovative equipment and skills promote the progression of endoscopic surgery from discectomy to decompression of spinal stenosis. Meanwhile, they also opened up the application of endoscopic surgery in a complicated situation. From the perspective of emerging technologies and techniques, the authors will review the evolution and describe the prospects of the interlaminar endoscopic spine surgery (IESS).

Augmented Reality Surgical Navigation in Spine Surgery to Minimize Staff Radiation Exposure

STUDY DESIGN

Prospective observational study.

OBJECTIVE

To assess staff and patient radiation exposure during augmented reality surgical navigation in spine surgery.

SUMMARY OF BACKGROUND DATA

Surgical navigation in combination with intraoperative three-dimensional imaging has been shown to significantly increase the clinical accuracy of pedicle screw placement. Although this technique may increase the total radiation exposure compared with fluoroscopy, the occupational exposure can be minimized, as navigation is radiation free and staff can be positioned behind protective shielding during three-dimensional imaging. The patient radiation exposure during treatment and verification of pedicle screw positions can also be reduced.

METHODS

Twenty patients undergoing spine surgery with pedicle screw placement were included in the study. The staff radiation exposure was measured using real-time active personnel dosimeters and was further compared with measurements using a reference dosimeter attached to the C-arm (i.e., a worst-case staff exposure situation). The patient radiation exposures were recorded, and effective doses (ED) were determined.

RESULTS

The average staff exposure per procedure was 0.21 ± 0.06 μSv. The average staff-to-reference dose ratio per procedure was 0.05% and decreased to less than 0.01% after a few procedures had been performed. The average patient ED was 15.8 ± 1.8 mSv which mainly correlated with the number of vertebrae treated and the number of cone-beam computed tomography acquisitions performed. A low-dose protocol used for the final 10 procedures yielded a 32% ED reduction per spinal level treated.

CONCLUSION

This study demonstrated significantly lower occupational doses compared with values reported in the literature. Real-time active personnel dosimeters contributed to a fast optimization and adoption of protective measures throughout the study. Even though our data include both cone-beam computed tomography for navigation planning and intraoperative screw placement verification, we find low patient radiation exposure levels compared with published data.

LEVEL OF EVIDENCE

3.

Safety and accuracy of spinal instrumentation surgery in a hybrid operating room with an intraoperative cone-beam computed tomography

Although spinal instrumentation technique has undergone revolutionary progress over the past few decades, it may still carry significant surgery-related risks. The purpose of the present study was to assess the radiological accuracy of spinal screw instrumentation using a hybrid operating room (OR) and quantify the related radiation exposure. This retrospective study included 33 cases of complex spine fusion surgeries that were conducted using a hybrid OR with a flat panel detector (FPD) angiography system. Twelve cases (36.4%) were cervical, and 21 (63.6%) were thoracolumbar. The average number of spine fusion levels was 3 and 4.8, respectively, at the cervical and thoracolumbar spine levels. A FPD angiography system was used for intraoperative cone-beam computed tomography (CBCT) to obtain multi-slice spine images. All operations were conducted under optimized radiation shielding. Entrance surface doses (ESDs) and exposure times were recorded in all cases. A total of 313 screws were placed. Satisfactory screw insertion could be achieved in all cases with safe screw placement in 97.4% and acceptable placement in 2.6%. None of the cases showed any significant anatomical violation by the screws. The radiation exposure to the patients was absolutely consistent with the desired ESD value, and that to the surgeons, under the annual dose limit. These results suggest that the hybrid OR with a FPD angiography system is helpful to achieve safe and precise spinal fusion surgery, especially in complex cases.

Accuracy of pedicle screw insertion by AIRO® intraoperative CT in complex spinal deformity assessed by a new classification based on technical complexity of screw insertion

PURPOSE

To develop a classification based on the technical complexity encountered during pedicle screw insertion and to evaluate the performance of AIRO^® CT navigation system based on this classification, in the clinical scenario of complex spinal deformity.

MATERIALS AND METHODS

31 complex spinal deformity correction surgeries were prospectively analyzed for performance of AIRO^® mobile CT-based navigation system. Pedicles were classified according to complexity of insertion into five types. Analysis was performed to estimate the accuracy of screw placement and time for screw insertion. Breach greater than 2 mm was considered for analysis.

RESULTS

452 pedicle screws were inserted (T1-T6: 116; T7-T12: 171; L1-S1: 165). The average Cobb angle was 68.3° (range 60°-104°). We had 242 grade 2 pedicles, 133 grade 3, and 77 grade 4, and 44 pedicles were unfit for pedicle screw insertion. We noted 27 pedicle screw breach (medial: 10; lateral: 16; anterior: 1). Among lateral breach (n = 16), ten screws were planned for in-out-in pedicle screw insertion. Among lateral breach (n = 16), ten screws were planned for in-out-in pedicle screw insertion. Average screw insertion time was 1.76 ± 0.89 min. After accounting for planned breach, the effective breach rate was 3.8% resulting in 96.2% accuracy for pedicle screw placement.

CONCLUSION

This classification helps compare the accuracy of screw insertion in range of conditions by considering the complexity of screw insertion. Considering the clinical scenario of complex pedicle anatomy in spinal deformity AIRO^® navigation showed an excellent accuracy rate of 96.2%.