Utility of a Navigated High-Speed Drill in Robotic-Assisted Screw Placement for Spine Surgery.

Purpose To elucidate the utility of a navigated high-speed drill used after the version upgrade in surgeries assisted by a spinal robotics system. Methods The subjects were 166 patients who underwent screw placement using a spinal robotics system between April 2021 to July 2023. A significant change during the study was the introduction of a navigated high-speed drill in 80 post-upgrade cases, aimed at improving drilling accuracy. Screw accuracy was analyzed using the Gertzbein and Robbins classification on postoperative CT scans. Screws placed before (pre-upgrade group: 718 screws in 86 cases) and after the system upgrade (post-upgrade group: 747 screws in 80 cases) were compared in terms of perfect accuracy and deviation rates. Results There were no significant differences in demographics or surgical details between the two groups. No significant differences were observed in the overall perfect accuracy rate and deviation rate (2.4% pre-upgrade vs. 2.0% post-upgrade) between the two groups. For the percutaneous pedicle screw (PPS), the perfect accuracy rate was significantly higher, and the deviation rate was significantly lower in the post-upgrade group (26.1% pre-upgrade vs. 4.4% post-upgrade). Notably, the post-upgrade group achieved 100% perfect accuracy and 0% deviation for the cortical bone trajectory screw (CBT) technique. Conclusions The introduction of the navigated high-speed drill did not significantly alter the overall perfect accuracy or deviation rates for robotic-assisted screw placement. However, its use did demonstrate improved outcomes in specific techniques such as PPS and CBT, indicating its potential value in addressing skiving in robotic-assisted minimally invasive surgeries.

Long-term changes in bone mineral density following adolescent idiopathic scoliosis surgery: a minimum 34-year follow-up.

PURPOSE: To investigate longitudinal changes in bone mineral density (BMD) in middle-aged female patients who underwent spinal fusion for adolescent idiopathic scoliosis (AIS). METHODS: The study subjects were 229 female patients who were diagnosed with AIS and underwent spinal fusion between 1968 and 1988. A two-step survey study was conducted on 19 female AIS patients. BMD, Z-scores, T-scores, and the prevalence of osteoporosis and osteopenia were compared between the initial (2014-2016) and second (2022) surveys. Correlations between the annual changes in Z-scores and T-scores with radiographic parameters, body mass index (BMI), and the number of remaining mobile discs were analyzed. RESULTS: BMD decreased significantly from the initial (0.802 ± 0.120 g/cm2) to the second survey (0.631 ± 0.101 g/cm2; p < 0.001). Z-scores decreased from 0.12 ± 1.09 to - 0.14 ± 1.04, while T-scores decreased significantly from - 0.70 ± 1.07 to - 1.77 ± 1.11 (p < 0.001). The prevalence of osteopenia and osteoporosis increased significantly from 36.8% to 89.5% (p = 0.002), but the increase in osteoporosis alone was not statistically significant (5.3% to 26.3%; p = 0.180). Moderate negative correlations were found between annual changes in Z-scores and both main thoracic (MT) curve (r = - 0.539; p = 0.017) and lumbar curve (r = - 0.410; p = 0.081). The annual change in T-scores showed a moderate negative correlation with the MT curve (r = - 0.411; p = 0.081). CONCLUSION: Significant reductions in BMD and an increased prevalence of osteopenia and osteoporosis were observed in middle-aged female AIS patients who had undergone spinal fusion. The decline in Z-scores in patients with AIS suggested that there was an accelerated loss of BMD compared with the general population. Larger residual curves could pose an added osteoporosis risk. Further research is needed to understand if the onset of osteoporosis in AIS patients is attributable to the condition itself or the surgical intervention.

Learning curves for robotic-assisted spine surgery: an analysis of the time taken for screw insertion, robot setting, registration, and fluoroscopy.

PURPOSE: The purpose of this study was to clarify the learning curve for robotic-assisted spine surgery. We analyzed the workflow in robotic-assisted spine surgery and investigated how much experience is required to become proficient in robotic-assisted spine surgery. METHODS: The data were obtained from consecutive 125 patients who underwent robotic-assisted screw placement soon after introducing a spine robotic system at a single center from April 2021 to January 2023. The 125 cases were divided into phases 1-5 of sequential groups of 25 cases each and compared for screw insertion time, robot setting time, registration time, and fluoroscopy time. RESULTS: There were no significant differences in age, body mass index, intraoperative blood loss, number of fused segments, operation time, or operation time per segment between the 5 phases. There were significant differences in screw insertion time, robot setting time, registration time, and fluoroscopy time between the 5 phases. The screw insertion time, robot setting time, registration time, and fluoroscopy time in phase 1 were significantly longer than those in phases 2, 3, 4, and 5. CONCLUSION: In an analysis of 125 cases after the introduction of the spine robotic system, the screw insertion time, robot setting time, registration time, and fluoroscopy time were significantly longer in the 25 cases in the period initially after introduction. The times were not significantly different in the subsequent 100 cases. Surgeons can be proficient in robotic-assisted spine surgery after their experience with 25 cases.

Comparison of Radiographic and Patient-Reported Outcomes After Surgery in Adolescent Idiopathic Scoliosis Between Robotics and Navigation: An Analysis Using Propensity Score Matching.

Purpose This study aimed to compare the radiographic and patient-reported outcomes after surgery in adolescent idiopathic scoliosis (AIS) between robotics and navigation using propensity score matching. Methods This retrospective study involved 50 patients undergoing posterior spinal fusion for AIS between October 2016 and August 2022, utilizing navigation or robotic systems, analyzing them using propensity score matching. The evaluations included assessments using X-ray, Scoliosis Research Society 22-Item (SRS-22) Questionnaire, and CT, considering variables such as age, gender, BMI, and Lenke type. Results Post matching, 13 cases each from robotics and navigation groups were compared. No significant differences were found in the demographic variables, preoperative X-ray parameters, and preoperative SRS-22 scores between the two groups. The robotics group demonstrated a higher perfect accuracy rate (94.0% vs. 84.7%, p=0.005) and a lower deviation rate in pedicle screw placements (1.6% vs. 4.1%, p=0.223). At one year postoperatively, there were no significant differences in the X-ray parameters between both groups. Likewise, no significant differences were found in each domain of SRS-22, but function, self-image, mental health, and satisfaction scores were numerically higher in the robotics group. Conclusion The application of a spinal robotic system in AIS surgery presented enhanced screw accuracy and lower deviation rates, compared to navigation, with no significant differences observed in the X-ray parameters and each domain of SRS-22 at one year postoperatively. This suggests that, to improve patient quality of life (QOL), it is essential for robotic-assisted spine surgery to focus not only on screw accuracy but also on the development of novel robotic-assisted techniques.

Nutritional Status Is Associated With Survival Following Spinal Surgery in Patients With Metastatic Spinal Tumors.

Background Preoperative and postoperative nutritional statuses are reported to influence the outcomes and complications of multidisciplinary treatment, including patient survival. However, a causal relationship between nutritional status and survival following spinal surgery has not been demonstrated in patients with metastatic spinal tumors. The present study was, therefore, designed to evaluate the correlation between the nutritional status and survival following spinal surgery in patients with metastatic spinal tumors. Methods Nutritional status was evaluated using the Japanese version of the modified Glasgow prognostic score (JmGPS), C-reactive protein-to-albumin ratio (CAR), prognostic nutrition index (PNI), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR), which were calculated from the results of preoperative laboratory tests. The survival period was defined as the interval between the day preoperative data were obtained and the day of death. Results Data from 57 of 113 consecutive surgeries were retrieved. The CAR, JmGPS, and PNI were significantly correlated with the survival period (CAR, r = -0.576, P < 0.01; JmGPS, r = -0.537, P < 0.01; PNI, r = 0.316, P = 0.02). Furthermore, patients with 0 points on the JmGPS had significantly longer survival. Using receiver operating characteristic curves, CAR cutoffs of ≥0.880 and ≤0.220 were found to be optimal in predicting the 90- and 180-day postoperative survival, respectively. Conclusions The findings of the present study indicate that preoperative assessment of the JmGPS, CAR, and PNI has utility in estimating nutritional status and predicting survival following spinal surgery in patients with metastatic spinal tumors.

Safety of robotic-assisted screw placement for spine surgery: Experience from the initial 125 cases.

BACKGROUND: The present study aimed to evaluate the safety of robot-assisted screw placement in 125 cases after introducing a spinal robotics system and to identify the situations where deviation was likely to occur. METHODS: The subjects were 125 consecutive patients who underwent robotic-assisted screw placement using a spinal robotics system (Mazor X Stealth Edition, Medtronic) from April 2021 to January 2023. The 1048 screws placed with robotic assistance were evaluated. We investigated intraoperative adverse events of the robotics system and complications occurring within 30 days after surgery. We evaluated screw accuracy and deviation and compared them for vertebral levels, screw insertion methods (open traditional pedicle screw [Open-PS], cortical bone trajectory screw [CBT], percutaneous pedicle screw [PPS], and S2 alar iliac screw [S2AIS]), diagnosis, and phases of surgical cases. RESULTS: The deviation rate of robotic-assisted screw placement for spine surgery was 2.2%. Complications were reoperation due to implant-related neurological deficit in 0.8% and surgical site infection in 0.8%. There was significant difference in the deviation rate between vertebral levels. The deviation rate of the T1-T4 level was high at 10.0%. There was significant difference in the deviation rate between Open-PS, CBT, PPS, and S2AIS. The PPSs had a high deviation rate of 10.3%. The deviation rates were not significantly different between patients with and without deformity. The deviation rate did not change depending on the experience of surgical cases, and the deviation rate was favorable from the onset. CONCLUSION: Although the robotic-assisted screw placement was safe, we should be extra vigilant when placing screws in the upper thoracic region (deviation rate 10.0%) and when using PPSs (deviation rate 10.3%).

Impact of the COVID-19 Pandemic on Middle-Aged and Older Patients With Adolescent Idiopathic Scoliosis Who Underwent Spinal Fusion: A Questionnaire-Based Survey.

Purpose To investigate the impact of the COVID-19 pandemic on middle-aged and older patients with adolescent idiopathic scoliosis (AIS) who underwent spinal fusion. Methods The subjects were 252 AIS patients who underwent spinal fusion between 1968 and 1988. The surveys were performed before the COVID-19 pandemic (a primary survey in 2014) and during the pandemic (a secondary survey in 2022). The self-administered questionnaires were mailed to the patients. We analyzed 35 patients (33 females and two males) who replied to both surveys. Results The pandemic had low impacts on 11 patients (31.4%). Two patients reported refraining from seeing a doctor because they were concerned about going to the clinic or hospital, eight reported that the pandemic impacted their work, and five reported fewer opportunities to go out (based on multiple-choice answers). Twenty-four patients reported that their lives were unaffected by the pandemic. No significant differences were detected between both surveys for Scoliosis Research Society-22 (SRS-22) in any domains (function, pain, self-image, mental, or satisfaction). The Oswestry Disability Index (ODI) questionnaires revealed a significant worsening of the survey during the pandemic compared with the survey before the pandemic. There was no significant difference in the impact of the pandemic between the ODI deterioration group (27.8%) and the ODI stable group (35.3%). Conclusion The COVID-19 pandemic had a low impact on 31.4% of middle-aged and older patients with AIS who underwent spinal fusion. The impact of the pandemic did not significantly differ between the groups with ODI deteriorations and the groups with stable ODI. The pandemic had a smaller impact on AIS patients at a minimum of 33 years after surgery.

Health-Related Quality of Life of Patients With Adolescent Idiopathic Scoliosis at Least 40 Years After Surgery.

STUDY DESIGN: Retrospective study. OBJECTIVE: The aim was to clarify the health-related quality of life (QOL) of patients who had adolescent idiopathic scoliosis (AIS) at a minimum of 40 years after surgery. SUMMARY OF BACKGROUND DATA: The postoperative health-related QOL of middle-aged patients with AIS has been reported to be good, but that of middle-aged and older patients with AIS has yet to be completely explored. MATERIALS AND METHODS: We included 179 patients with AIS who underwent spinal fusion(s) between 1968 and 1982. We conducted three surveys in 2009, 2014, and 2022. Patients self-administered both the Scoliosis Research Society-22 and the Roland-Morris Disability questionnaires three times (in 2009, 2014, and 2022) and the Oswestry Disability Index (ODI) questionnaire was self-administered in 2014 and 2022. We considered patients who responded to all three surveys in 2009, 2014, and 2022. RESULTS: For the Scoliosis Research Society-22 questionnaires, no significant differences were detected among the three time points (2009, 2014, and 2022) for total scores, function domain, pain domain, self-image domain, mental domain, or satisfaction domain. The results of the Roland-Morris Disability Questionnaire were also not significantly different among the surveys over time. The ODI questionnaires revealed a significant worsening of the 2022 results compared with the 2014 results. Eight patients (29.6%) who had an ODI deterioration of 10% or more had numerically fewer mobile lumbar disks than those with <10% deterioration of the ODI, although the difference did not reach statistical significance. CONCLUSION: Among patients with AIS who underwent spinal fusion(s) between 1968 and 1982, we found health-related QOL to be maintained over the last 13 years. Relatively good QOL was appreciated in this population of patients who are now middle-aged and older.

Accuracy of robotic-assisted pedicle screw placement comparing junior surgeons with expert surgeons: Can junior surgeons place pedicle screws as accurately as expert surgeons?

BACKGROUND: The purpose of this study was to verify whether a spine robotic system was useful for junior surgeons. METHODS: Twenty-seven patients underwent posterior spinal fusion with open surgery using a spine robotic system (Mazor X Stealth Edition, Medtronic Inc., Dublin, Ireland) from April to August 2021. Pedicle screw insertions were performed by five surgeons. The surgeon and insertion time were recorded for each pedicle screw. Two surgeons who are board-certified spine surgeons by the Japanese Society for Spine Surgery and Related Research (JSSR) were defined as the expert surgeon group. Three surgeons who were training to acquire qualifications as JSSR board certified spine surgeons were defined as the junior surgeon group. In postoperative CT images, the deviation of 255 pedicle screws was evaluated using the Gertzbein-Robbins (GR) grades. RESULTS: In the expert surgeon group, the GR grades were Grade A for 79 screws (90.8%), Grade B for 6 (6.9%), Grade C for 2 (2.3%), and 0 (0%) for Grades D and E. I In the junior surgeon group, the GR grades were Grade A for 162 screws (96.4%), Grade B for 6 (3.6%), and 0 (0%) for Grades C, D, and E. There was no significant difference in the deviation rate between surgeon groups (p = 0.08). The mean insertion times were 174.5 ± 83.0 s in the expert surgeon group and 191.0 ± 111.0 s in the junior surgeon group. There was no significant difference in the insertion time between surgeon groups (p = 0.22). CONCLUSIONS: There were no significant differences in the deviation rate and the insertion time of robotic-assisted pedicle screw placement between expert surgeons and junior surgeons who were training to acquire qualifications as JSSR board certified spine surgeons. Robotic-assisted pedicle screw placement can be effectively employed by junior surgeons.

Accuracy of computer-assisted pedicle screw placement for adolescent idiopathic scoliosis: a comparison between robotics and navigation.

PURPOSE: To compare the accuracy of pedicle screw placement in adolescent idiopathic scoliosis (AIS) between robotics and navigation and clarify the factors that cause screw deviation when robotics is used. METHODS: Fifty consecutive patients who underwent posterior spinal fusions with computer-assisted pedicle screw placement including robotics and navigation for AIS were included. A total of 741 pedicle screws (250: Robot group, 491: Navi group) were evaluated on postoperative CT images. A rate of penetration of ≥ 2 mm was calculated as the deviation rate. After propensity score matching, we examined vertebral levels, the distance from the reference frame (RF), and the pedicle channel grade as factors for deviation. RESULTS: The deviation rate was significantly lower in the Robot group than in the Navi group (Robot group: 1.6%, Navi group: 7.5%). After propensity score matching, 22 cases were extracted. At T5-T8, the deviation rate of the Robot group was significantly lower than that of the Navi group. In the Robot group, the T2-T4 deviation rate was significantly higher than at the other vertebral levels. The distance from the RF didn't affect the deviation rate. The deviation rate of pedicle channel Grade 4 (inner diameter of less than 1 mm) was significantly higher than for the other grades. CONCLUSION: The deviation rate of robotics was 1.6%, lower than that of navigation. The narrow pedicles with an inner diameter of less than 1 mm (deviation rate: 22.2%) and the upper thoracic level (deviation rate: 14.3%) were factors related to screw deviation even when using robotics.

Robotics is useful for less-experienced surgeons in spinal deformity surgery.

PURPOSE: To verify whether robotics was useful for surgeons who had less experience with spinal deformity surgery. METHODS: A retrospective review was conducted of 70 consecutive patients who underwent robotic-assisted pedicle screw placements with open procedures using a spine robotic system (Mazor X Stealth Edition) at a single institution from April 2021 to April 2022. Gertzbein-Robbins grades were used to assess the deviation of the 599 pedicle screws in the postoperative CT images. The rate of Grade A was considered the perfect accuracy rate, and the rate of Grades C, D, and E was calculated as the deviation rate. The perfect accuracy rate and deviation rate were compared between the spinal deformity and the non-deformity groups. The perfect accuracy rate, deviation rate, and screw insertion time were compared in the spinal deformity cases between the expert surgeon group and the less-experienced surgeon group. RESULTS: The deviation rate of the spinal deformity group was higher than that of the non-deformity group even though there was no statistically significant difference (spinal deformity group: 2.3%, non-deformity group: 1.2%, p = 0.350). In the spinal deformity cases, there was no significant difference in the perfect accuracy rate between the expert surgeon group and the less-experienced surgeon group, but the deviation rate was significantly lower in the less-experienced surgeon group (expert surgeon group: 5.0%, less-experienced surgeon group: 0%, p = 0.008). The screw insertion time was significantly shorter in the less-experienced surgeon group. CONCLUSION: Robotics is particularly useful for surgeons with less experience in spinal deformity surgery.

The Learning Curve of Robotic-Assisted Pedicle Screw Placements Using the Cumulative Sum Analysis: A Study of the First 50 Cases at a Single Center.

Introduction: The purpose of this study was to clarify how many cases surgeons need to experience to pass the learning phase of robotic-assisted spine surgery using the cumulative sum (CUSUM) analysis. Methods: A retrospective review was conducted on the initial 50 consecutive patients who underwent robotic-assisted pedicle screw placements with open procedures using a spine robotic system (Mazor X Stealth Edition) at a single center from April 2021 to January 2022. There were 19 male and 31 female patients with a mean age of 58.7 (range, 13-86) years. To split the surgeries into the early and late phases using the CUSUM analysis of screw insertion time, we compared the screw insertion time, the robot setting time, the registration time, and the operation time in the early and late phases. Results: The screw insertion time, the robot setting time, and the registration time declined as the number of surgical cases increased. The operation time did not decline as the number of surgical cases increased. The learning curve for screw insertion time can be separated into two stages based on the CUSUM analysis. The first 23 cases were in the early phase, and the later 27 cases were in the late phase. The mean screw insertion time was reduced from 3.2 min in the first 23 cases to 2.7 min in the subsequent 27 cases. The robot setting time and registration time in the late phase were also significantly shorter than those in the early phase. Conclusions: The screw insertion time, robot setting time, and registration time decreased with experience. After 23 cases, surgeons passed the learning phase of robotic-assisted spine surgery and became more proficient.

Diagnosis of Spinal Infection with Alpha-defensin Lateral Flow Test: A Preliminary Report.

Introduction: The alpha-defensin lateral flow test has been used in periprosthetic joint infection as a diagnostic support tool because of its simplicity and speed. However, the test has not been used to diagnose spinal infections. The purpose of this study was to investigate the efficacy of the alpha-defensin lateral flow test for diagnosing spinal infections. Methods: The subjects were 11 patients who were suspected of having spinal infections from October 2019 to August 2021 and underwent biopsies at a single institution. There were nine male and two female patients, with an average age of 60.7 (14-87) years. For diagnosing infection, the patient's consent for biopsy was obtained, and the sample was collected by computed tomography-guided aspiration biopsy or open biopsy at the site considered to be a possible abscess. The samples were subjected to a bacterial culture test, an acid-fast bacillus culture test, and an alpha-defensin lateral flow test (SynovasureⓇ lateral flow test; Zimmer Biomet, IN, USA). Results: Of the 11 suspected spinal infections, the alpha-defensin lateral flow test was positive in 8 cases, negative in 2 cases, and undeterminable in 1 case. Of the 10 cases excluding the undeterminable case, the definitive diagnosis was 9 cases of spinal infection (spondylitis: 6 cases, spinal implant infection: 3 cases) and 1 case of vertebral body fracture. The alpha-defensin lateral flow test demonstrated a sensitivity of 88.9%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 50%. The biopsy sample culture test demonstrated a sensitivity of 77.8%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 33.3%. Conclusions: We suggested that the alpha-defensin lateral flow test might be useful as a diagnostic support tool for spinal infections.

Screw Insertion Time, Fluoroscopy Time, and Operation Time for Robotic-Assisted Lumbar Pedicle Screw Placement Compared With Freehand Technique.

Introduction The purpose of this study was to clarify the superiority of robotic-assisted lumbar pedicle screw placement in terms of screw insertion time, fluoroscopy time, and operation time. Methods The subjects were 46 patients who underwent a posterior lumbar interbody fusion with an open procedure for lumbar degenerative disease from April 2021 to February 2022. The robot group contained 29 cases of screw insertion using a spine robotic system (Mazor X Stealth Edition, Medtronic Inc., Dublin, Ireland). The freehand group contained 17 cases of screw insertion with the freehand technique utilizing the conventional C-arm image guidance. The screw insertion time, fluoroscopy time, and operation time were compared between the robot and the freehand group. Results The screw insertion time did not differ significantly between the two groups (robot group: 179.0 ± 65.2 sec; freehand group: 164.2 ± 83.4 sec; p = 0.507). The fluoroscopy time was significantly shorter in the robot group (robot group: 28.3 ± 25.8 sec; freehand group: 67.5 ± 72.8 sec; p = 0.011). The fluoroscopy time per segment was also significantly shorter in the robot group (robot group: 17.8 ± 23.0 sec; freehand group: 60.2 ± 74.8 sec; p = 0.007). The operation time was significantly longer in the robot group (robot group: 249.6 ± 72.5 min; freehand group: 195.8 ± 60.1 sec; p = 0.013), but the operation time per segment did not differ significantly between the two groups (robot group: 144.1 ± 39.0 min; freehand group: 159.7 ± 34.4 min; p = 0.477). Conclusions The screw insertion time and operation time per segment were similar when employing the spine robotic system compared to the freehand technique; however, the fluoroscopy time was shorter. The fluoroscopy time per segment in the robot group was 29.6% of the time of the freehand group using the C-arm. The surgeon's radiation exposure is thought to be decreased since the spine robotic system shortens the fluoroscopy time.

Accuracy and Screw Insertion Time of Robotic-Assisted Cortical Bone Trajectory Screw Placement for Posterior Lumbar Interbody Fusion: A Comparison of Early, Middle, and Late Phases.

Introduction The purpose of this study was to evaluate robotic-assisted cortical bone trajectory (CBT) screw placement. Early, middle, and late phases of robotic-assisted CBT screw placement were compared for accuracy and screw insertion time by comparing time and accuracy in every phase.  Methods A retrospective review was conducted on the initial 40 patients who underwent spinal fusion using CBT screws in one institution from September 2021 to September 2022 utilizing a spine surgery robot system (Mazor X Stealth Edition, Medtronic Inc., Dublin, Ireland). The inclusion criterion was one- or two-level posterior lumbar interbody fusion (PLIF). Exclusion criteria were 1) patients who underwent posterior-lateral fusion in other segments, 2) patients who underwent additional decompression in other segments, 3) patients who underwent reoperation, and 4) patients with spondylolysis. The deviation of the CBT screw was evaluated on computed tomography (CT) one week after surgery using the Gertzbein-Robbins grade system. The rate of Grade A was considered the perfect accuracy rate, and the rate of penetration of 2 mm or more (Grades C, D, and E) was calculated as the deviation rate. To assess the learning curve, patients were divided into three groups. The first 10 cases were in the early phase group, the subsequent 10 cases were in the middle phase group, and the last 10 cases were in the late phase group. We compared the perfect accuracy rate, deviation rate, operative time, operative time per segment, intraoperative blood loss, registration time, and screw insertion time among the three groups. Results Thirty patients met the criteria. Overall, the perfect accuracy (Grade A) rate of the screw was 95.3% and the deviation rate was 1.4%. The perfect accuracy rate was 90.4% in the early phase, 95.5% in the middle phase, and 100% in the late phase. The deviation rate was 3.8% in the early phase, 0% in the middle phase, and 0% in the late phase, and there was no statistically significant difference between the three groups. Among the three groups, the operative time, the operative time per segment, the intraoperative blood loss, and the registration time were not significantly different. There was no significant difference in the screw insertion time among the three groups, but it decreased with experience (early phase: 156.9 ± 54.7 sec, middle phase: 139.9 ± 41.6 sec, and late phase: 106.4 ± 39.9 sec, p=0.060). The screw insertion time of the late phase tended to be shorter than that of the early phase (p=0.052). Conclusions The deviation rate of robotic-assisted CBT screw placement with one- or two-level PLIF was 1.4%, which was highly accurate. The deviation rate was 3.8% in the early phase, 0% in the middle phase, and 0% in the late phase. Although the deviation rate was low even in the early period, the screw insertion time in the early 10 cases tended to be longer than that in the late 10 cases. After passing the experience of 10 cases, this study concluded that robotic-assisted CBT screw placement was proficient.

Tranexamic Acid Reduces Total Blood Loss and the Amount of Stored Preoperative Autologous Blood Donation Needed for Adolescent Idiopathic Scoliosis Patients Undergoing Posterior Spinal Fusion.

Introduction There are few published studies on posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) that have reported that the stored amounts of autologous blood donation (ABD) needed for the procedure were estimated by taking into account total blood loss (TBL). The aim of this study was to clarify the following clinical questions: (1) Does the use of tranexamic acid (TXA) reduce the TBL during PSF for AIS? (2) What volume of ABD should be stored to avoid allogeneic blood transfusions? Methods This study investigated 44 female patients who underwent PSF for AIS. A total of 33 patients underwent PSF without TXA (non-TXA group) and 11 patients underwent PSF with TXA (TXA group). TBL was determined by the hemoglobin (Hb) balance method calculated with circulating blood volume, Hb levels, hematocrit (Ht) levels before and three days after surgery, and the volumes of blood transfusions, including stored ABD. For the TXA patients, TBL was used to determine the appropriate amount of stored ABD and the number of ABD collections. Results The amount of TBL was lower in the TXA group compared to the non-TXA group. The mean required volume of stored ABD in the TXA group was 218.2 ± 577.3 mL, with a required maximum volume of 699.0 mL. The proportions of patients requiring allogeneic blood transfusion were as follows: 72.7% for those with no ABD collection, 45.5% for one ABD collection, and 0% for two ABD collections when TXA was used during surgery.  Conclusions TXA reduced the TBL of patients undergoing PSF for AIS. The maximum amount of stored ABD needed was 699.0 mL. Allogeneic blood transfusion can be avoided by storing two ABD collections when TXA is used during the surgery.

Optimization of the Revised Tokuhashi Scoring System: New Prognostic Criteria for Metastatic Spinal Tumor in Surgical Cases.

INTRODUCTION: The revised Tokuhashi scoring system has been used to predict survival in patients with metastatic spinal tumors. Because of the rapid progress of cancer therapy, the original criteria of the revised Tokuhashi scoring system became in recent years unsuitable. The study aim was to evaluate the validity of the revised Tokuhashi scoring system in patients who underwent spinal surgery and to establish new prognostic criteria. METHODS: The study enrolled 85 patients with metastatic spinal tumors who underwent spinal surgery. The patients' survival outcomes in October 2019 were as follows: 57 patients died; 10 were alive; and 18 had unknown prognoses. The study evaluated the validity of the Tokuhashi scoring system, and established and validated the new prognostic criteria. RESULTS: The accuracies of the Tokuhashi scoring system were 66.7% in the short-term group, 60% in the midterm group, and 100% in the long-term group. Among the patients who died, the survival period and total score were significantly correlated. Total score cutoff point was six points in the patients whose predicted survival was <6 months. Total score cutoff point was eight points in the patients whose predicted survival was ≥1 year. CONCLUSIONS: As the prognosis of patients has improved in recent years, the original criteria of the revised Tokuhashi scoring system have been questioned as to their suitability to current treatments. Especially, the survival period among the patients with total scores of 7 and 8 points was not accurate. According to this study, the new prognostic criteria of the revised Tokuhashi scoring system were set to 0 to 6 points for the short-term group, 7 points for the midterm group, and 8 to 15 points for the long-term group.

Mobile Application for Scoliosis Screening Using a Standard 2D Digital Camera.

Several scoliosis detection systems, using three-dimensional (3D) cameras or sensors, have been developed in recent years. Because these systems require specific 3D digital cameras or sensors, and the equipment is expensive, they are rarely used in many countries and regions. The development of a scoliosis screening system that uses standard two-dimensional (2D) digital cameras that come with tablet personal computers (PCs) and smartphones will facilitate the efforts made to detect scoliosis patients on a global scale. The aim of this technical note was to report on a mobile application for scoliosis screening that uses a standard 2D digital camera. The subjects were patients aged 10 years or older who visited our outpatient clinic for scoliosis or suspected scoliosis and underwent whole-spine radiography. Photographs of subjects were obtained using a standard 2D digital camera connected to a tablet PC. For analysis, we used the simplified scoliosis diagnosis support application (Cobb First, Its Corporation, Kawasaki, Japan) which operates on Windows 10 operating system (OS). When an image was imported into the application, it was displayed within a grid. The grid consisted of four columns and 40 rows and was divided into 160 areas. Each image was converted into binarized image data by demarcating skin and background color. The image of the subject was displayed as a black subject on a white background. Two types of conditions were presented to process differences in the environment versus skin color. A binarized image with a clear outline was selected. The determination was displayed as a percentage of the black area in each grid. In each row of the grid, the left and right sides of the black area were compared, and the part with the larger area with respect to the opposite side was colored and displayed. Depending on the ratio of the difference, it was possible to display green, yellow, and red. If this mobile application is available for clinical use, it has the potential to improve the accuracy of screening by physicians and nurses. Furthermore, it may also be used globally to check for possible evidence of scoliosis at home to facilitate the early detection of patients who require a medical checkup for scoliosis. Although it is essential to perform a radiographic examination for the definitive diagnosis of scoliosis, our future goal is to limit radiation exposure and replace a radiologic method with one based on a tablet PC or smartphone. A mobile application using a standard 2D digital camera may improve the accuracy of screening scoliosis by physicians and may have global application in home environments.

Pulmonary Function Improves in Patients with Adolescent Idiopathic Scoliosis who Undergo Posterior Spinal Fusion Regardless of Thoracoplasty: A Mid-Term Follow-Up.

INTRODUCTION: The purpose of the present study was to determine, in a mid-term follow-up 5 years or more after surgery, the forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and expiratory flow in patients with adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion (PSF) with or without thoracoplasty. METHODS: The subjects were 134 patients with AIS who underwent PSF between 2004 and 2013. Forty-five patients agreed to participate in the study. We divided the patients into two groups as follows: 24 patients who underwent PSF with thoracoplasty from 2004 to 2010 in the TP group and 21 patients who underwent PSF without thoracoplasty from 2011 to 2013 in the non-TP group. We evaluated whole spine X-ray imaging and pulmonary function tests (PFTs) in these patients. PFTs measured FVC, FEV1, peak expiratory flow (PEF), maximum expiratory flow at 50% FVC (V50), maximum expiratory flow at 25% FVC (V25), and the ratio of V50 to V25 (V50/V25). RESULTS: The main thoracic curves were 53.6 ± 10.1° before surgery, 19.8 ± 7.6° 1 week after surgery, 22.3 ± 8.3° 2 years after surgery, and 23.3 ± 7.6° at the most recent observation. Compared with preoperative values, FVC, FEV1, and % FEV1 were improved significantly at the most recent observation. No significant difference was observed between % FVC before surgery and at the most recent observation. Compared with preoperative values, PEF, V50, and V25 were improved significantly at the most recent observation. V50/V25 did not change significantly. The changes in PFT values in the TP group and the non-TP group were compared. No significant differences were observed in FVC, % FVC, FEV1, % FEV1, PEF, V50, or V25. CONCLUSIONS: Regardless of whether thoracoplasty was performed or not, FVC, FEV1, and expiratory flow were improved 5 years or later after PSF.

Anchor type at upper instrumented vertebra and postoperative shoulder imbalance in patients with Lenke type 1 adolescent idiopathic scoliosis.

PURPOSE: To clarify the impact of anchor type at upper instrumented vertebra (UIV) on postoperative shoulder imbalance in patients with Lenke type 1 adolescent idiopathic scoliosis (AIS) who underwent posterior spinal fusion. METHODS: Subjects were 81 patients with Lenke type 1 AIS who underwent posterior spinal fusion between 2004 and 2013. Twenty-five patients agreed to participate in the study. We divided the patients into two groups: Hook group (15 patients with hooks at UIV who underwent surgery between 2004 and 2011) and PS group (ten patients with pedicle screws at UIV who underwent surgery between 2012 and 2013). To evaluate shoulder balance, first thoracic vertebra tilt angle (T1 tilt), clavicle angle (CA), and radiographic shoulder height (RSH) were measured. RESULTS: There were no significant differences in preoperative T1 tilt, CA, or RSH between the both groups. The postoperative 1-week, 2-year, and most recently observed T1 tilts were significantly smaller in the Hook group than in the PS group. There were no significant differences in postoperative 1-week, 2-year, and most recently observed CAs between the two groups. Although there were no significant differences in 1-week postoperative RSH between the groups, the 2-year postoperative RSH was significantly smaller in the Hook group than in the PS group. The most recently observed RSH tended to be smaller in the Hook group than in the PS group, but the difference was not significant. CONCLUSIONS: In the PS group, poor shoulder balance remained over the long term. The hooks at UIV adjusted postoperative shoulder balance.