Publications by authors named "Manabu Ito"

156 Publications

Considerations and Strategies for Restarting Elective Spine Surgery in the Midst of a Pandemic of COVID-19.

Spine Surg Relat Res 2021 21;5(2):52-60. Epub 2020 Dec 21.

Department of Orthopaedic Surgery, the National Hospital Organization Hokkaido Medical Center, Sapporo, Japan.

The 2019 coronavirus disease (COVID-19) pandemic outbreak has rapidly spread to the globe, causing severe global socioeconomic disruption on an unprecedented scale. As the first wave of COVID-19 pandemic is now going to settle down, many medical organizations are in the process of reopening surgical services. This paper describes a few key factors that spine surgeons should consider prior to resuming elective spine services namely, local outbreak situations, availability of hospital resources, manpower and personal protective equipment (PPE). Spine surgeons should prioritize their operating list based on clinical indications and likely benefits from surgical intervention so as to make optimum use of hospital resources and operating room listings. International organizations have published on general principles and recommendations on how to restart elective surgery. However, with different regions at varying phases of the outbreak and unpredictable nature of the COVID-19 pandemic, a general set of practice guidelines may not be applicable. This paper also proposes, on top of peri-operative precautionary measures already in place, clearly-defined risk stratification algorithms for hospital visitors, as well as a disease-testing protocol for patients planned for elective surgery. It is of critical importance for surgeons to define key areas of concern and assimilate these principles into clearly-defined algorithms which can be applied to the field of spine surgery so as to help re-establish continuity of care for patients.
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http://dx.doi.org/10.22603/ssrr.2020-0154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8026206PMC
December 2020

Toward the Development of a Comprehensive Clinically Oriented Patient Profile: A Systematic Review of the Purpose, Characteristic, and Methodological Quality of Classification Systems of Adult Spinal Deformity.

Neurosurgery 2021 Feb 15. Epub 2021 Feb 15.

Department of Orthopaedic Surgery, Radboud University Medical Center, Nijmegen, The Netherlands.

Background: Existing adult spinal deformity (ASD) classification systems are based on radiological parameters but management of ASD patients requires a holistic approach. A comprehensive clinically oriented patient profile and classification of ASD that can guide decision-making and correlate with patient outcomes is lacking.

Objective: To perform a systematic review to determine the purpose, characteristic, and methodological quality of classification systems currently used in ASD.

Methods: A systematic literature search was conducted in MEDLINE, EMBASE, CINAHL, and Web of Science for literature published between January 2000 and October 2018. From the included studies, list of classification systems, their methodological measurement properties, and correlation with treatment outcomes were analyzed.

Results: Out of 4470 screened references, 163 were included, and 54 different classification systems for ASD were identified. The most commonly used was the Scoliosis Research Society-Schwab classification system. A total of 35 classifications were based on radiological parameters, and no correlation was found between any classification system levels with patient-related outcomes. Limited evidence of limited quality was available on methodological quality of the classification systems. For studies that reported the data, intraobserver and interobserver reliability were good (kappa = 0.8).

Conclusion: This systematic literature search revealed that current classification systems in clinical use neither include a comprehensive set of dimensions relevant to decision-making nor did they correlate with outcomes. A classification system comprising a core set of patient-related, radiological, and etiological characteristics relevant to the management of ASD is needed.
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http://dx.doi.org/10.1093/neuros/nyab023DOI Listing
February 2021

Risk factors of multidrug-resistant pyogenic spondylitis in thoraco-lumbar spine: A retrospective study of 122 cases.

J Orthop Sci 2021 Jan 6. Epub 2021 Jan 6.

Department of Orthopaedic Surgery, Hokkaido University Hospital, North-14, West-5, Kita-ku, Sapporo, Hokkaido 060-8648, Japan.

Background: The number of spinal infections has been increasing in developed countries due to the increase of aged or immunosuppressed patients. Spondylitis caused by multidrug-resistant (MDR) bacterial infection often become intractable and require long-term antibiotic therapy and multiple surgeries. Therefore, it is of great importance to understand risk factors for MDR spinal infections. The aim of this study was to elucidate the risk factors for MDR bacterial spondylitis.

Methods: A total of 122 patients (82 men, 40 women; average age: 63.8 y) with thoracic/lumbar spondylitis who underwent posterolateral full-endoscopic debridement and irrigation were included. The organisms detected by this endoscopic procedure were investigated, and the incidence and risk factors for MDR bacterial infection were retrospectively analyzed.

Results: Cultures of specimens obtained by endoscopic procedures were positive in 78 patients (63.9%). Among 68 isolated bacteria, MDR bacteria accounted for 47.1%. Multivariate analysis showed that significant risk factors for MDR bacterial infection included autoimmune connective tissue disease (P = 0.03) and central venous catheter (P = 0.02). The incidence of MDR bacteria in patients who were administered a broad-spectrum antibiotic for more than 1 month preoperatively was 64.0%, which was significantly higher than in patients who were administered a broad-spectrum antibiotic for less than 1 month and patients who were administered a narrow-spectrum antibiotic (P < 0.01, P < 0.01, respectively).

Conclusions: The significant risk factors for MDR bacterial spondylitis included immunosuppressed conditions, such as autoimmune connective tissue disease, presence of central venous catheter, and longer administration periods of a broad-spectrum antibiotic. In patients with pyogenic spondylitis who could not be controlled with previous antibiotics and whose result of culture was negative, administration of anti-MRSA antibiotics would be considered when they have the risk factors identified in this study.
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http://dx.doi.org/10.1016/j.jos.2020.11.020DOI Listing
January 2021

Expert consensus on surgical treatment for adolescent idiopathic scoliosis in Japan.

J Orthop Sci 2020 Sep 18. Epub 2020 Sep 18.

Department of Orthopaedic Surgery, Surgical Science, Tokai University School of Medicine, Kanagawa, Japan; International Affairs Committee of the Japanese Scoliosis Society, Chiba, Japan. Electronic address:

Background: Surgical treatment for adolescent idiopathic scoliosis (AIS) has changed significantly with the advent of new medical devices and surgical procedures. Today, pre- and postoperative management differs widely between institutions. The purpose of this study is to establish consensus regarding the surgical management of AIS in Japan through the use of a questionnaire survey of experienced spine deformity surgeons.

Methods: From February to March 2020, experienced spine deformity surgeons who perform more than 25 cases of AIS surgery annually were asked to respond to a questionnaire request regarding AIS surgical management formulated by the International Affairs Committee of the Japanese Scoliosis Society. For each of the questions, consensus was achieved upon a 70% agreement among respondents.

Results: Responses were received from 25 of the 32 (78%) experienced spine deformity surgeons. The average age of the responding surgeons was 52 years with an average practice experience of 28 year. Consensus was achieved on 74 (76%) of the 97 aspects of care presented in the questionnaire and is broken down as follows: 12 of 17 items for preoperative management, all 5 items for perioperative management, 11 of 14 items for surgical technique, 9 of 15 items for implant selection, 6 of 8 items for bone grafting, 7 of 10 items for blood conservation, 5 of 7 items for postoperative management, all 17 items for postoperative evaluation, and 2 of 4 items for aftercare.

Conclusions: Expert consensus was achieved on 74 aspects of the surgical management of AIS in Japan. In implant selection and aftercare, consensus was obtained in less than 70% of the aspects, revealing differences in AIS management between institutions. These findings on AIS surgery in Japan, informed by expert opinion, will conceivably help spine deformity surgeons determine appropriate surgical management of AIS.
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http://dx.doi.org/10.1016/j.jos.2020.08.002DOI Listing
September 2020

Impact of Consultation Length on Satisfaction in Patients with Chronic Low Back Pain: A Nationwide Multicenter Study in Japan.

Spine Surg Relat Res 2020 29;4(3):208-215. Epub 2020 Jan 29.

Department of Orthopaedic Surgery, Japan Medical Alliance, Ebina General Hospital, Ebina, Japan.

Introduction: Chronic low back pain (CLBP) is a major health burden worldwide and requires patient satisfaction with treatment. Consultation length can be an important factor in patient satisfaction, but few studies have investigated the impact of consultation length on satisfaction in patients with CLBP. This study tried to elucidate the impact of consultation length on clinical outcomes in patients with CLBP.

Methods: This study is part of an analysis using the database of the nationwide, multicenter cohort for CLBP performed by the Project Committee of the Japanese Society for Spine Surgery and Related Research. A total of 427 patients aged 20-85 years (median age, 73.0 years; female, 58.6%) with CLBP were prospectively followed-up monthly for 6 months. Multivariable nonlinear regression analyses were performed to assess the effect of consultation length on outcome measures including subjective satisfaction score, EuroQol 5-dimension, Japanese Orthopaedic Association (JOA) score, Roland-Morris Disability Questionnaire, JOA Back Pain Evaluation Questionnaire, visual analog scale (VAS) and Medical Outcome Survey short-form 8-item health survey that evaluated at the next phase. Furthermore, we assessed whether the effect of consultation length on patient satisfaction was modified by the baseline Brief Scale for Psychiatric Problems in Orthopaedic Patients (BS-POP) score for patient and physician versions.

Results: VAS for CLBP was the only score that correlated significantly with consultation length (P = 0.018). Satisfaction score showed a significant positive correlation with consultation length in patients with the highest baseline BS-POP scores (P < 0.2). Moreover, consultation lengths more than 7.6 min and 15.1 min offered increase of satisfaction if patients show the highest BS-POP scores on patient and physician versions, respectively.

Conclusions: These findings suggest that a sufficiently long consultation is an important factor for subjective satisfaction in the patients with CLBP, particularly in patients with psychological problems.
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http://dx.doi.org/10.22603/ssrr.2019-0111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447350PMC
January 2020

Spine Surgery: Precautions and Strategies to Minimize Perioperative Risks Amid COVID-19 Outbreak.

Spine Surg Relat Res 2020 3;4(3):192-198. Epub 2020 Jun 3.

Department of Orthopaedic Surgery, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan.

Coronavirus disease 2019 (COVID-19) outbreak is an ongoing pandemic that has shocked the world. It has brought severe socioeconomic disruptions on a global scale that is unprecedented. On the frontline, the medical world is facing mounting pressure and challenges to clinical work. During this escalating worldwide crisis, spine care providers around the world are needing accurate and precise information on how surgical safety for themselves and the patients can be ensured. With the ultimate objective of formulating a standardized work process for spine practices, this article aimed to summarize some key principles from various international recommendations/consensus and combined evidence- and experience-based practice from medical communities around the world.
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http://dx.doi.org/10.22603/ssrr.2020-0076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447339PMC
June 2020

Impact of lowest instrumented vertebra tilt and rotation on uninstrumented lumbar curve and L4 tilt in thoracic adolescent idiopathic scoliosis.

J Neurosurg Spine 2020 Jun 12:1-9. Epub 2020 Jun 12.

1Department of Orthopaedic Surgery, Hokkaido University Hospital.

Objective: Controversy exists regarding the effects of lowest instrumented vertebra (LIV) tilt and rotation on uninstrumented lumbar segments in adolescent idiopathic scoliosis (AIS) surgery. Because the intraoperative LIV tilt from the inferior endplate of the LIV to the superior sacral endplate is not stable after surgery, the authors measured the LIV angle of the instrumented thoracic spine as the LIV angle of the construct. This study aimed to evaluate the effects of the LIV angle of the construct and the effects of LIV rotation on the postoperative uninstrumented lumbar curve and L4 tilt in patients with thoracic AIS.

Methods: A retrospective correlation and multivariate analysis of a prospectively collected, consecutive, nonrandomized series of patients at a single institution was undertaken. Eighty consecutive patients with Lenke type 1 or type 2 AIS treated with posterior correction and fusion were included. Preoperative and 2-year postoperative radiographic measurements were the outcome measures for this study. Outcome variables were postoperative uninstrumented lumbar segments (LIV tilt, LIV translation, uninstrumented lumbar curve, thoracolumbar/lumbar [TL/L] apical vertebral translation [AVT], and L4 tilt). The LIV angle of the construct was measured from the orthogonal line drawn from the upper instrumented vertebra to the LIV. Multiple stepwise linear regression analysis was conducted between outcome variables and patient demographics/radiographic measurements. There were no study-specific biases related to conflicts of interest.

Results: Predictor variables for postoperative uninstrumented lumbar curve were the postoperative LIV angle of the construct, number of uninstrumented lumbar segments, and flexibility of TL/L curve. Specifically, a lower postoperative uninstrumented lumbar curve was predicted by a lower absolute value of the postoperative LIV angle of the construct (p < 0.0001). Predictor variables for postoperative L4 tilt were postoperative LIV rotation, preoperative L4 tilt, and preoperative uninstrumented lumbar curve. Specifically, a lower postoperative L4 tilt was predicted by a lower absolute value of postoperative LIV rotation (p < 0.0001).

Conclusions: The LIV angle of the construct significantly affected the LIV tilt, uninstrumented lumbar curve, and TL/L AVT. LIV rotation significantly affected the LIV translation and L4 tilt.
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http://dx.doi.org/10.3171/2020.4.SPINE191297DOI Listing
June 2020

Impact of background factors on outcomes of pharmacological therapy for chronic low back pain: A nationwide multicenter prospective study.

J Orthop Sci 2021 Jan 28;26(1):92-102. Epub 2020 Feb 28.

Department of Orthopaedic Surgery, Japan Medical Alliance, Ebina General Hospital, Ebina, Japan.

Background: Chronic low back pain (CLBP) is a major cause of chronic pain with nociceptive, neuropathic or both pain components, and a leading cause of disability. The objectives of this study were to determine the impact of background factors including previous use of drugs on outcomes of pharmacological therapy for CLBP in a nationwide multicenter prospective study.

Methods: The subjects were 474 patients (male: 41.9%, median age: 73.0) with CLBP. Background factors that could influence outcomes after pharmacological treatment for 6 months were examined: age, gender, body mass index (BMI), duration of CLBP, osteoporosis, history of spinal surgery, history of malignant tumor, smoking habit, employment status (yes or no), exercise habit (frequency), number of live-in family members, having something to do for pleasure, Center for Epidemiologic Studies depression scale (CES-D) score, and medication at baseline. Japanese Orthopaedic Association (JOA) score, visual analogue scale (VAS) for LBP, JOA Back Pain Evaluation Questionnaire (JOABPEQ), Roland-Morris Disability Questionnaire (RDQ), Short-form 8-item health survey (SF-8), and EQ-5D were used for evaluation at baseline and after 6 months. Multivariate linear regression models were used in statistical analysis.

Results: Drugs for neuropathic pain at baseline (p < 0.001), Tramacet® at baseline (p < 0.05), weak opioids at baseline (p < 0.05), older age (p < 0.001), long disease duration (p < 0.005), history of spinal surgery (p < 0.001), and smoking habit (p < 0.001) had significant negative effects on outcomes. Employment (p < 0.05), exercise habit (p < 0.05), and CED-D at baseline (p < 0.001) had positive effects on outcomes.

Conclusions: This is the first study to identify significant prognostic factors for outcomes of pharmacological treatment of CLBP. The neuropathic pain component of CLBP at baseline is a major significant negative factor for most outcomes involving improved pain, activities of daily life, and quality of life. Treatment strategies developed with consideration of these factors may be advantageous for recovery from CLBP.
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http://dx.doi.org/10.1016/j.jos.2020.02.003DOI Listing
January 2021

Early Clinical Results of Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion: A New Modified Technique for Treating Degenerative Lumbar Spondylolisthesis.

Spine Surg Relat Res 2019 28;3(4):327-334. Epub 2018 Dec 28.

Department of Orthopaedic surgery, Hokkaido University Hospital, Sapporo, Japan.

Introduction: Lumbar interbody fusion is used to treat degenerative lumbar spondylolisthesis with instability. We developed a device that safely expands a percutaneous path through Kambin's triangle and used it via a new technique: percutaneous endoscopic transforaminal lumbar interbody fusion (PETLIF). We report in this study the details and outcomes of this procedure after a one year follow-up.

Methods: Twenty-five patients requiring interbody fusion for degenerative spondylolisthesis of the L4 vertebra were enrolled in this study. The procedure involved percutaneous posterior pedicle screw placement to correct spondylolisthesis. After the exterior of the L5 vertebra superior articular protrusion was shaved with a percutaneous endoscopic drill in order to expand the safe zone, the oval sleeve was inserted through Kambin's triangle and was rotated to expand the disk height and create a path toward the vertebral disk. The interbody cage was inserted against the J-shaped nerve retractor, with the exiting nerve root retracted. Indirect decompression of spinal canal stenosis was expected because the vertebral body spondylolisthesis had been corrected and the interbody distance was expanded. Thus, no direct decompression was performed posterolaterally.

Results: The mean follow-up period, surgery time, and blood loss were 22.7 months, 125.4 min, and 64.8 mL, respectively. The Japanese Orthopaedic Association score improved from 13.3 to 28.0. The Roland-Morris Disability Questionnaire score improved from 10.3 to 3.3. All items were evaluated both preoperatively and one year postoperatively. Bone fusion was observed one year postoperatively in 22 out of 25 patients.

Conclusions: These results demonstrate the feasibility and efficacy of PETLIF for treating degenerative lumbar spondylolisthesis. This minimally invasive procedure is useful and has wide applicability. To obtain safe and favorable results, necessary surgical techniques must be mastered, and surgical equipment, including that for neural monitoring, is required.
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http://dx.doi.org/10.22603/ssrr.2018-0058DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6834458PMC
December 2018

A Review of the Historical Evolution, Biomechanical Advantage, Clinical Applications, and Safe Insertion Techniques of Cervical Pedicle Screw Fixation.

Spine Surg Relat Res 2019 Apr 10;3(2):126-135. Epub 2018 Oct 10.

Department of orthopaedics, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan.

Cervical spine instrumentation is evolving with an aim of stabilizing traumatic and non-traumatic cases of the cervical spine with a beneficial reduction, better biomechanical strength, and a strong construct with minimal intraoperative, as well as immediate and late postoperative complications. The evolution from interspinous wiring till cervical pedicle screws has changed the outlook in treating the cervical spine pathologies with maximum 3D stability, decreasing the duration of postoperative immobilization and hospital stay. Some complications associated with the use of cervical pedicle screw can be catastrophic. This review article discusses the morphometry of cervical pedicle; indications, biomechanical superiority, tricks, and pitfalls of cervical pedicle screw; complications and technical advancements in targeting safe surgery; and future directions of cervical pedicle screw instrumentation.
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http://dx.doi.org/10.22603/ssrr.2018-0055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690082PMC
April 2019

Genome-wide association study identifies 14 previously unreported susceptibility loci for adolescent idiopathic scoliosis in Japanese.

Nat Commun 2019 08 15;10(1):3685. Epub 2019 Aug 15.

Laboratory for Bone and Joint Diseases, Center for Integrative Medical Sciences, RIKEN, Tokyo, 108-8639, Japan.

Adolescent idiopathic scoliosis (AIS) is the most common pediatric spinal deformity. Several AIS susceptibility loci have been identified; however, they could explain only a small proportion of AIS heritability. To identify additional AIS susceptibility loci, we conduct a meta-analysis of the three genome-wide association studies consisting of 79,211 Japanese individuals. We identify 20 loci significantly associated with AIS, including 14 previously not reported loci. These loci explain 4.6% of the phenotypic variance of AIS. We find 21 cis-expression quantitative trait loci-associated genes in seven of the fourteen loci. By a female meta-analysis, we identify additional three significant loci. We also find significant genetic correlations of AIS with body mass index and uric acid. The cell-type specificity analyses show the significant heritability enrichment for AIS in multiple cell-type groups, suggesting the heterogeneity of etiology and pathogenesis of AIS. Our findings provide insights into etiology and pathogenesis of AIS.
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http://dx.doi.org/10.1038/s41467-019-11596-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6695451PMC
August 2019

Cost-effectiveness analysis of the pharmacological management of chronic low back pain with four leading drugs.

J Orthop Sci 2019 Sep 21;24(5):805-811. Epub 2019 Jun 21.

Department of Orthopaedic Surgery, Japan Medical Alliance, Ebina General Hospital, Ebina, Japan.

Background: Chronic low back pain is a major health problem that has a substantial effect on people's quality of life and places a significant economic burden on healthcare systems. However, there has been little cost-effectiveness analysis of the treatments for it. Therefore, the purpose of this prospective observational study was to evaluate the cost-effectiveness of the pharmacological management of chronic low back pain.

Methods: A total of 474 patients received pharmacological management for chronic low back pain using four leading drugs for 6 months at 28 institutions in Japan. Outcome measures, including EQ-5D, the Japanese Orthopaedic Association (JOA) score, the JOA back pain evaluation questionnaire (BPEQ), the Roland-Morris Disability Questionnaire, the Medical Outcomes Study SF-8, and the visual analog scale, were investigated at baseline and every one month thereafter. The incremental cost-utility ratio (ICUR) was calculated as drug cost over the quality-adjusted life years. An economic estimation was performed from the perspective of a public healthcare payer in Japan. Stratified analysis based on patient characteristics was also performed to explore the characteristics that affect cost-effectiveness.

Results: The ICUR of pharmacological management for chronic low back pain was JPY 453,756. Stratified analysis based on patient characteristics suggested that the pharmacological treatments for patients with a history of spine surgery or cancer, low frequency of exercise, long disease period, low scores in lumbar spine dysfunction and gait disturbance of the JOA BPEQ, and low JOA score at baseline were not cost-effective.

Conclusions: Pharmacological management for chronic low back pain is cost-effective from the reference willingness to pay. Further optimization based on patient characteristics is expected to contribute to the sustainable development of a universal insurance system in Japan.
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http://dx.doi.org/10.1016/j.jos.2019.06.004DOI Listing
September 2019

Responding to Intraoperative Neuromonitoring Changes During Pediatric Coronal Spinal Deformity Surgery.

Global Spine J 2019 May 8;9(1 Suppl):15S-21S. Epub 2019 May 8.

AOSpine Knowledge Forum Deformity, Davos, Switzerland.

Study Design: Retrospective case study on prospectively collected data.

Objectives: The purpose of this explorative study was: 1) to determine if patterns of spinal cord injury could be detected through intra-operative neuromonitoring (IONM) changes in pediatric patients undergoing spinal deformity corrections, 2) to identify if perfusion based or direct trauma causes of IONM changes could be distinguished, 3) to observe the effects of the interventions performed in response to these events, and 4) to attempt to identify different treatment algorithms for the different causes of IONM alerts.

Methods: Prospectively collected neuromonitoring data in pre-established forms on consecutive pediatric patients undergoing coronal spinal deformity surgery at a single center was reviewed. Real-time data was collected on IONM alerts with >50% loss in signal. Patients with alerts were divided into 2 groups: unilateral changes (direct cord trauma), and bilateral MEP changes (cord perfusion deficits).

Results: A total of 97 pediatric patients involving 71 females and 26 males with a mean age of 14.9 (11-18) years were included in this study. There were 39 alerts in 27 patients (27.8% overall incidence). All bilateral changes responded to a combination of transfusion, increasing blood pressure, and rod removal. Unilateral changes as a result of direct trauma, mainly during laminotomies for osteotomies, improved with removal of the causative agent. Following corrective actions in response to the alerts, all cases were completed as planned. Signal returned to near baseline in 20/27 patients at closure, with no new neurological deficits in this series.

Conclusion: A high incidence of alerts occurred in this series of cases. Dividing IONM changes into perfusion-based vs direct trauma directed treatment to the offending cause, allowing for safe corrections of the deformities. Patients did not need to recover IONM signal to baseline to have a normal neurological examination.
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http://dx.doi.org/10.1177/2192568219836993DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6512195PMC
May 2019

What Should an Ideal Adult Spinal Deformity Classification System Consist of?: Review of the Factors Affecting Outcomes of Adult Spinal Deformity Management.

Asian Spine J 2019 08 10;13(4):694-703. Epub 2019 Apr 10.

Department of Orthopaedic Surgery, Uijeongbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea.

This literature review aims to determine potential clinical factors or comorbidities besides radiological parameters that affect the outcome of adult spinal deformity (ASD) management and review existing classifications associated with ASD. ASD is a multifactorial disease that comprises pathologies like radiological spine deformity, coexistence of spinal canal stenosis, radiculopathy, and multiple comorbidities. The available classification systems of ASD are predominantly based on radiological parameters and do not consider related clinical conditions. ASD patients with different combinations of these parameters behave differently and need different management strategies. We conducted a narrative literature review with search limited to English language of PubMed/MEDLINE using Medical Subject Heading (MeSH) terms. The terms specific to the review were ASD and several other related terminologies. We analyzed the information of the selected papers including factors affecting surgical outcomes for degenerative scoliosis. We reviewed 614 citations. Based on the inclusion criteria, 39 citations were selected for full-text retrieval; of these, 28 were excluded because of not fulfilling the inclusion criteria. Thus, 11 studies were selected and included for the final analysis. The presence of leg pain, spinal stenosis, obesity, osteoporosis, smoking, and age of patients were major influencing factors. Furthermore, the factors included in the available classifications, such as the Scoliosis Research Society-Schwab classifications, were reviewed and results were tabulated. This review highlights the significance of neurological symptoms, spinal stenosis, osteoporosis, obesity, age, and smoking, which markedly affect the management of ASD. With increasing number of patients being diagnosed and treated with ASD, there has been a growing need to comprehensively classify these patients into clinicoradiological subgroups.
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http://dx.doi.org/10.31616/asj.2018.0309DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6680036PMC
August 2019

Heating sensation in patients with and without spinal fixation devices during MRI examination at different magnetic field strengths.

J Magn Reson Imaging 2019 02 14;49(2):525-533. Epub 2018 Oct 14.

Division of Biomedical Engineering and Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.

Background: Radiofrequency (RF) heating during MRI theoretically increases with magnetic field strength. In addition, implanted metallic devices are reported to further increase RF heating. However, a detailed evaluation of this type of heating remains scarce in clinical practice.

Purpose: To assess possible risks and discomfort related to RF heating during MRI examinations of patients with and without metallic implantable devices.

Study Type: A retrospective study of previous questionnaire results on the heating sensation during MRI examinations of the lumbar spine.

Subjects: In all, 715 patients, of whom 101 had implanted lumbar spine fixation devices.

Field Strength/sequence: 1T and 3T/T - and T -weighted imaging.

Assessment: The number of patients who perceived heating around the lumbar spine or other regions during the MRI examination.

Statistical Tests: A chi-square test with respect to static field strength B , presence of lumbar spine fixation devices, and duration of the MRI examination.

Results: The number of patients who perceived heating around the lumbar spine during the MRI examination significantly increased from 5.0% at 1T to 47.5% at 3T (P < 0.001), without a significant difference between patients with and without lumbar spine fixation devices (P = 0.23 at 1T, P = 0.48 at 3T), and regardless of the duration of the MRI examination (P = 0.88 at 1T, P = 0.15 at 3T).

Data Conclusion: Sensation of RF heating increased by around 10 times from 1T to 3T MRI examination, but the influence of implanted lumbar spine fixation devices on the RF heating sensation has not been observed.

Level Of Evidence: 4 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:525-533.
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http://dx.doi.org/10.1002/jmri.26307DOI Listing
February 2019

Classification of Adult Spinal Deformity: Review of Current Concepts and Future Directions.

Spine Surg Relat Res 2019 Jan 29;3(1):17-26. Epub 2018 May 29.

Department of Orthopedic Surgery, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan.

Although adult spinal deformity (ASD) has become a global health problem, the classification system and optimal surgical treatment for ASD is yet to be standardized worldwide. A significant part of the population, as high as 10%, in industrialized societies will be aged above 65 years within the next 10 years. Herein, a systematic review of the scientific literature related to the classification and treatment of ASD was conducted wherein historical to the most recent classifications of ASD were reviewed. By discussing the benefits and limitations of the previous classification systems and considering the factors affecting the clinical outcomes of surgical treatment of ASD, this article would like to propose future directions for the development of a new classification system for ASD.
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http://dx.doi.org/10.22603/ssrr.2017-0100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690115PMC
January 2019

Development of a New Punch Head Shape to Replicate Scale-Up Issues on a Laboratory Tablet Press III: Replicating Sticking Phenomenon Using the SAS Punch and Evaluation by Checking the Tablet Surface Using 3-D Laser Scanning Microscope.

J Pharm Sci 2018 08 22;107(8):2144-2151. Epub 2018 Apr 22.

Formulation Technology, DI Plus Unit, EDCS, Eisai Co., Ltd., Kakamigahara-Shi, Gifu 501-6195, Japan.

Sticking is a common observation in the scale-up stage on the punch tip using a commercial tableting machine. The difference in the total compression time between a laboratory tableting machine and a commercial one is considered one of the main root causes of scale-up issues in the tableting processes. The proposed "Size Adjusted for Scale-up punch" can be used to adjust the consolidation and dwell times for commercial tableting machine. As a result, the sticking phenomenon is able to be replicated at the pilot scale stage. As reported in this article, the quantification of sticking was done using a 3-D laser scanning microscope to check the tablet surface. It was shown that the sticking area decreased with the addition of magnesium stearate in the formulation, but the sticking depth was not affected by the additional amount of magnesium stearate. It is proposed that the use of a 3-D laser scanning microscope can be applied to evaluate sticking as a process analytical technology tool, and so sticking can be monitored continuously without stopping the machine.
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http://dx.doi.org/10.1016/j.xphs.2018.04.012DOI Listing
August 2018

Trabecular health of vertebrae based on anisotropy in trabecular architecture and collagen/apatite micro-arrangement after implantation of intervertebral fusion cages in the sheep spine.

Bone 2018 03 11;108:25-33. Epub 2017 Dec 11.

Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871, Japan. Electronic address:

Healthy trabecular bone shows highly anisotropic trabecular architecture and the preferential orientation of collagen and apatite inside a trabecula, both of which are predominantly directed along the cephalocaudal axis. This makes trabecular bone stiff in the principally loaded direction (cephalocaudal axis). However, changes in these anisotropic trabecular characteristics after the insertion of implant devices remain unclear. We defined the trabecular architectural anisotropy and the preferential orientation of collagen and apatite as parameters of trabecular bone health. In the present study, we analyzed these parameters after the implantation of two types of intervertebral fusion cages, open and closed box-type cages, into sheep spines for 2 and 4months. Alteration and evolution of trabecular health around and inside the cages depended on the cage type and implantation duration. At the boundary region, the values of trabecular architectural anisotropy and apatite orientation for the closed-type cages were similar to those for isotropic conditions. In contrast, significantly larger anisotropy was found for open-type cages, indicating that the open-type cage tended to maintain trabecular anisotropy. Inside the open-type cage, trabecular architectural anisotropy and apatite orientation significantly increased with time after implantation. Assessing trabecular anisotropy might be useful for the evaluation of trabecular health and the validation and refinement of implant designs.
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http://dx.doi.org/10.1016/j.bone.2017.12.012DOI Listing
March 2018

A functional variant in MIR4300HG, the host gene of microRNA MIR4300 is associated with progression of adolescent idiopathic scoliosis.

Hum Mol Genet 2017 10;26(20):4086-4092

Laboratory of Bone and Joint Diseases, RIKEN Center for Integrative Medical Sciences, Tokyo 108-8639, Japan.

Adolescent idiopathic scoliosis (AIS) is a common spinal deformity affecting millions of children. Since treatment and prognosis of AIS depend on curve progression, identifying factors related to AIS curve progression is important in its management. Although several genetic loci for AIS occurrence are reported, no locus for curve progression has been identified. To identify genes associated with AIS progression, we conducted a genome-wide association study followed by a replication study using a total of 2,543 AIS subjects who were evaluated for the curve progression. We identified a significantly associated locus on chromosome 11q14.1 (P = 1.98 × 10-9, odds ratio = 1.56). In silico and in vitro analyses identified a functional variant, rs35333564 in MIR4300HG, the host gene of a microRNA, MIR4300. The genomic region containing rs35333564 had enhancer activity, which was decreased in its risk allele. Our data suggest that decrease of MIR4300 is related to AIS progression.
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http://dx.doi.org/10.1093/hmg/ddx291DOI Listing
October 2017

A Replication Study for the Association of rs11190870 With Curve Severity in Adolescent Idiopathic Scoliosis in Japanese.

Spine (Phila Pa 1976) 2018 05;43(10):688-692

Laboratory of Bone and Joint Diseases, RIKEN Center for Integrative Sciences, Tokyo, Japan.

Study Design: Case-only study.

Objective: The aim of this study was to confirm the association of rs11190870 with adolescent idiopathic scoliosis (AIS) severity in Japanese patients with AIS.

Summary Of Background Data: Although the association of rs11190870 with AIS susceptibility is replicated in multiple ethnics, the association of rs11190870 with curve severity is controversial. Since the previous studies are of small, we performed a replication study using far larger number of patients than previous studies.

Methods: A total of 1860 Japanese patients with AIS who had reached skeletal maturity or undergone surgical fusion were included in the study. We evaluated the association between rs11190870 and AIS progression for the entire group, and then for patients grouped according to a severe curve (a Cobb angle of ≥40°) or mild curve (a Cobb angle <30°). Because braces could affect the results of the present study, patients in the mild-curve group were divided according to whether or not they had worn a brace. We then evaluated associations between rs11190870 genotype and curve severity in these groups.

Results: The mean Cobb angles were 54.8° ± 12.1° in the severe-curve group and 24.4° ± 4.0° in the mild-curve group. The difference in rs11190870 risk-allele frequency between the severe- and mild-curve groups was evaluated. No significant differences were observed. We then examined the association of rs11190870 risk-allele frequency between patients in the mild- and severe-curve groups using the χ test for three models, and found a marginal association between rs11190870 and curve severity in the dominant model (P = 0.035, odds ratio = 1.51).

Conclusion: We found no association between rs11190870 and curve severity using the criteria of previous study. However, we found a marginal association between rs11190870 and curve severity. Large-scale replication studies that consider skeletal maturity and brace history, including replication studies in other ethnic groups, would be helpful for clarifying the association.

Level Of Evidence: 4.
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http://dx.doi.org/10.1097/BRS.0000000000002413DOI Listing
May 2018

An international consensus on the appropriate evaluation and treatment for adults with spinal deformity.

Eur Spine J 2018 03 5;27(3):585-596. Epub 2017 Aug 5.

Department of Orthopedics, Radboud University Medical Center, Nijmegen, The Netherlands.

Purpose: Evaluation and surgical management for adult spinal deformity (ASD) patients varies between health care providers. The purpose of this study is to identify appropriateness of specific approaches and management strategies for the treatment of ASD.

Methods: From January to July 2015, the AOSpine Knowledge Deformity Forum performed a modified Delphi survey where 53 experienced deformity surgeons from 24 countries, rated the appropriateness of management strategies for multiple ASD clinical scenarios. Four rounds were performed: three surveys and a face-to-face meeting. Consensus was achieved with ≥70% agreement.

Results: Appropriate surgical goals are improvement of function, pain, and neural symptoms. Appropriate preoperative patient evaluation includes recording information on history and comorbidities, and radiographic workup, including long standing films and MRI for all patients. Preoperative pulmonary and cardiac testing and DEXA scan is appropriate for at-risk patients. Intraoperatively, appropriate surgical strategies include long fusions with deformity correction for patients with large deformity and sagittal imbalance, and pelvic fixation for multilevel fusions with large curves, sagittal imbalance, and osteoporosis. Decompression alone is inappropriate in patients with large curves, sagittal imbalance, and progressive deformity. It is inappropriate to fuse to L5 in patients with symptomatic disk degeneration at L5-S1.

Conclusions: These results provide guidance for informed decision-making in the evaluation and management of ASD. Appropriate care for ASD, a very diverse spectrum of disease, must be responsive to patient preference and values, and considerations of the care provider, and the healthcare system. A monolithic approach to care should be avoided.
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http://dx.doi.org/10.1007/s00586-017-5241-1DOI Listing
March 2018

Complications Associated With Lateral Interbody Fusion: Nationwide Survey of 2998 Cases During the First 2 Years of Its Use in Japan.

Spine (Phila Pa 1976) 2017 Oct;42(19):1478-1484

Department of Orthopedic Surgery, Osaka Rosai Hospital, Nagasone-cho, Kita-ku, Sakai, Osaka, Japan.

Study Design: Retrospective nationwide questionnaire-based survey of complications.

Objective: To elucidate the incidence of complications and risk factors associated with lateral interbody fusion (LIF).

Summary Of Background Data: After its introduction to Japan in February 2013, the numbers of LIF cases have increased substantially because of the advantages of this minimally invasive procedure. However, LIF has the potential risk of several complications unique to the procedure. Although there are many reports of complications, no nationwide survey has been conducted.

Methods: Questionnaires were sent to all Japanese Society for Spine Surgery and Related Research (JSSR) members. Questionnaires requested information about surgical procedures (XLIF or OLIF), patient characteristics, preoperative diagnosis, complications, salvage procedures, final outcomes, and the surgeon's experience of LIF. The data from replies received between March 2013 and April 2015 were recorded on a web site and the details of complications were analyzed by a JSSR research team.

Results: Seventy-one institutions (12.3%) answered "yes" to LIF experience and 2998 cases (1995 XLIF and 1003 OLIF) were enrolled in this study. The response rate was 86.1%. A total of 540 complications were reported, of which 474 (84.8%) could be further analyzed. The overall complication rate was 18.0%. The most frequent complications were sensory nerve injury (5.1%) and psoas weakness (4.3%) and the majority resolved spontaneously. The rates of major vascular injury, bowel injury, and surgical site infection were 0.03%, 0.03%, and 0.7%, respectively. The overall reoperation rate was 2.2%. Higher rates of sensory nerve injury and psoas weakness were reported for XLIF and higher rates of peritoneal laceration and ureteral injury were reported for OLIF.

Conclusion: A nationwide survey of complications associated with LIF was conducted. Although the majority of complications were minor, a relatively high rate of complications was reported. Approach-related specific features of the two procedures were identified.

Level Of Evidence: 4.
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http://dx.doi.org/10.1097/BRS.0000000000002139DOI Listing
October 2017

Effectiveness of monotherapy and combined therapy with calcitonin and minodronic acid hydrate, a bisphosphonate, for early treatment in patients with new vertebral fractures: An open-label, randomized, parallel-group study.

J Orthop Sci 2017 May 18;22(3):536-541. Epub 2017 Jan 18.

National Hospital Organization Hokkaido Medical Center, Yamanote 5-7, Nishi-ku, Sapporo, Hokkaido, 063-0005, Japan.

Background: Evidence related to the effectiveness of combination drug therapy for the treatment of osteoporosis is currently considered insufficient. Therefore, this study was performed to clarify the effects of monotherapy, and combination therapy, with a bisphosphonate (minodronic acid hydrate), a bone resorption inhibitor, and calcitonin (elcatonin), which is effective for the alleviation of pain due to vertebral fractures in osteoporotic patients.

Methods: Study participants comprised of 51 female subjects with post-menopausal osteoporosis, whose main complaint was acute lower back pain caused by vertebral fractures. Subjects were randomly allocated into three groups and then administered with either intramuscular injections of elcatonin at a dose of 20 units weekly, minodronic acid hydrate at a dose of 1 mg daily, or a combination of these two drugs. As primary endpoints, time-dependent changes in levels of pain were assessed using a visual analog scale from baseline to 6 months of duration. In addition, we examined the effects of monotherapies, and a combination therapy on bone resorption, with changes in bone mineral density at 4 sites and advanced hip assessment parameters from baseline to 6 months. A two-tailed significance level of 5% was used for hypothesis testing.

Results: Elcatonin monotherapy showed some alleviation of pain immediately after any vertebral fractures, which was more than in the minodronic acid hydrate monotherapy group. In addition, the minodronic acid hydrate monotherapy group experienced more effective inhibited bone resorption than the elcatonin monotherapy group. In the combination therapy, the efficacy for alleviating pain and inhibiting bone resorption was equivalent to the effect observed in the elcatonin and minodronic acid hydrate monotherapy groups respectively, with further improved values of bone mineral density observed in the femoral neck and lumbar vertebrae, and in parameters of advanced hip assessment compared with both monotherapy groups.

Conclusions: Combination therapy with elcatonin and minodronic acid hydrate appears to be an effective treatment for osteoporosis patients with lower back pain, caused by fresh vertebral fractures.
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http://dx.doi.org/10.1016/j.jos.2016.12.021DOI Listing
May 2017

Evaluation of perforated demineralized dentin scaffold on bone regeneration in critical-size sheep iliac defects.

Clin Oral Implants Res 2017 Nov 17;28(11):e227-e235. Epub 2017 Jan 17.

Department of Spine and Spinal Cord Disorders, National Hospital Organization, Hokkaido Medical Center, Sapporo, Japan.

Objectives: Regenerating critical-size bone injury is a major problem that continues to inspire the design of new graft materials. Therefore, tissue engineering has become a novel approach for targeting bone regeneration applications. Human teeth are a rich source of stem cells, matrix, trace metal ions, and growth factors. A vital tooth-derived demineralized dentin matrix is acid-insoluble and composed of cross-linked collagen with growth factors. In this study, we recycled human non-functional tooth into a unique geometric dentin scaffold, entitled perforated root-demineralized dentin matrix (PR-DDM). The aim of this study was to evaluate the feasibility of PR-DDM as the scaffold for regenerating bone in critical-size iliac defects.

Material And Methods: Artificial macro-pores (1 mm in diameter) were added to human vital wisdom tooth after removing the enamel and pulp portions. The modified tooth was demineralized in 0.34 N HNO for 30 min and is referred to as PR-DDM scaffold. Critical-size defect (10 mm × 15 mm × 9 mm Ø) was created in the iliac crest of six adult sheep. The in vivo bone regeneration by the scaffold was evaluated by micro-CT, 3D micro-CT, and histological examination at 2 and 4 months post-implantation.

Results: PR-DDM exhibited better bone ingrowth, especially in the artificial macro-pores. The results of micro-CT and 3D micro-CT revealed good union between scaffold and native bone. New bone formation was observed in almost all portions of PR-DDM. Higher bone volume inside the scaffold was detected at 4 months compared with 2 months. New bone ingrowth was ankylosed with PR-DDM, and both osteoinduction and osteoconduction capability of PR-DDM were confirmed histologically. The ratio of new bone formation was higher at 4 months compared with 2 months by histomorphometric analysis.

Conclusions: Altogether, these results demonstrated that the human tooth-derived graft material with a unique geometric structure, PR-DDM, contributed to active bone ingrowth in critical-size bone defects. This novel scaffold may have great utility in the near-future clinical application.
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http://dx.doi.org/10.1111/clr.13000DOI Listing
November 2017

Effectiveness of elcatonin for alleviating pain and inhibiting bone resorption in patients with osteoporotic vertebral fractures.

J Bone Miner Metab 2017 Sep 9;35(5):544-553. Epub 2016 Nov 9.

National Hospital Organization Hokkaido Medical Center, Hokkaido, Japan.

Elderly patients with osteoporotic vertebral fractures often experience severe pain that reduces their quality of life (QOL). Calcitonin, a bone resorption inhibitor, has been reported to alleviate pain in such patients; however, few clinical studies have demonstrated this effect. The objective of this study was to compare changes in pain scores, activities of daily living (ADL), QOL, bone resorption, bone mineral density (BMD), and fracture healing among patients with new vertebral fractures who received different treatment modalities. We conducted an open-label, multicenter, randomized, parallel control group study comprising 107 female patients ≥55 years old with acute back pain from vertebral fracture. All subjects received either intramuscular injections of elcatonin, a derivative of calcitonin, or an oral nonsteroidal antiinflammatory drug (NSAID) combined with an active vitamin D (VD3) analogue for 6 months. The pain was assessed using a visual analogue scale, and ADL and QOL were assessed using questionnaires. BMD was measured using dual-energy X-ray absorptiometry. A two-tailed significance level of 5% was used. The elcatonin IM group had significantly higher QOL score at 2 weeks and later, and significantly lower VAS and ADL scores than those in the NSAID + VD3 group at 1 month and later. The elcatonin IM group had significantly reduced TRACP-5b levels compared with those in the NSAID + VD3 group at 3 months and later and significantly higher percent changes in BMD than the NSAID + VD3 group. These results suggest that elcatonin significantly alleviated pain, inhibited bone resorption, and improved ADL, QOL, and BMD compared with NSAID + VD3.
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http://dx.doi.org/10.1007/s00774-016-0791-6DOI Listing
September 2017

A biomechanical investigation of mandibular molar implants: reproducibility and validity of a finite element analysis model.

Int J Implant Dent 2015 Dec 28;1(1):10. Epub 2015 Apr 28.

Department of Geriatric Dentistry, Showa University, School of Dentistry, 2-1-1 Kitasenzoku, Ota-ku, Tokyo, 145-8515, Japan.

Background: Three-dimensional finite element analysis (FEA) is effective in analyzing stress distributions around dental implants. However, FEA of living tissue involves many conditions, and the structures and behaviors are complex; thus, it is difficult to ensure the validity of the results. To verify reproducibility and validity, we embedded implants in experimental models and constructed FEA models; implant displacements were compared under various loading conditions.

Methods: Implants were embedded in the molar regions of artificial mandibles to fabricate three experimental models. A titanium superstructure was fabricated and three loading points (buccal, central, and lingual) were placed on a first molar. A vertical load of 100 N was applied to each loading point and implant displacements were measured. Next, the experimental models were scanned on micro-computed tomography (CT) and three-dimensional FEA software was used to construct two model types. A model where a contact condition was assumed for the implant and artificial mandible (a contact model) was constructed, as was a model where a fixation condition was assumed (a fixation model). The FEA models were analyzed under similar conditions as the experimental models; implant displacements under loading conditions were compared between the experimental and FEA models. Reproducibility of the models was assessed using the coefficient of variation (CV), and validity was assessed using a correlation coefficient.

Results: The CV of implant displacement was 5% to 10% in the experimental and FEA models under loading conditions. Absolute values of implant displacement under loading were smaller in FEA models than the experimental model, but the displacement tendency at each loading site was similar. The correlation coefficient between the experimental and contact models for implant displacement under loading was 0.925 (p < 0.01). The CVs of equivalent stress values in the FEA models were 0.52% to 45.99%.

Conclusions: Three-dimensional FEA models were reflective of experimental model displacements and produced highly valid results. Three-dimensional FEA is effective for investigating the behavioral tendencies of implants under loading conditions. However, the validity of the absolute values was low and the reproducibility of the equivalent stresses was inferior; thus, the results should be interpreted with caution.
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http://dx.doi.org/10.1186/s40729-015-0011-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5005693PMC
December 2015

Effects of Multilevel Facetectomy and Screw Density on Postoperative Changes in Spinal Rod Contour in Thoracic Adolescent Idiopathic Scoliosis Surgery.

PLoS One 2016 26;11(8):e0161906. Epub 2016 Aug 26.

Department of Orthopaedic Surgery, Hokkaido University Hospital, Sapporo, Hokkaido, Japan.

Flattening of the preimplantation rod contour in the sagittal plane influences thoracic kyphosis (TK) restoration in adolescent idiopathic scoliosis (AIS) surgery. The effects of multilevel facetectomy and screw density on postoperative changes in spinal rod contour have not been documented. This study aimed to evaluate the effects of multilevel facetectomy and screw density on changes in spinal rod contour from before implantation to after surgical correction of thoracic curves in patients with AIS prospectively. The concave and convex rod shapes from patients with thoracic AIS (n = 49) were traced prior to insertion. Postoperative sagittal rod shape was determined by computed tomography. The angle of intersection of the tangents to the rod end points was measured. Multiple stepwise linear regression analysis was used to identify variables independently predictive of change in rod contour (Δθ). Average Δθ at the concave and convex side were 13.6° ± 7.5° and 4.3° ± 4.8°, respectively. The Δθ at the concave side was significantly greater than that of the convex side (P < 0.0001) and significantly correlated with Risser sign (P = 0.032), the preoperative main thoracic Cobb angle (P = 0.031), the preoperative TK angle (P = 0.012), and the number of facetectomy levels (P = 0.007). Furthermore, a Δθ at the concave side ≥14° significantly correlated with the postoperative TK angle (P = 0.003), the number of facetectomy levels (P = 0.021), and screw density at the concave side (P = 0.008). Rod deformation at the concave side suggests that corrective forces acting on that side are greater than on the convex side. Multilevel facetectomy and/or screw density at the concave side have positive effects on reducing the rod deformation that can lead to a loss of TK angle postoperatively.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161906PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5001696PMC
August 2017

Critical Values of Facet Joint Angulation and Tropism in the Development of Lumbar Degenerative Spondylolisthesis: An International, Large-Scale Multicenter Study by the AOSpine Asia Pacific Research Collaboration Consortium.

Global Spine J 2016 Aug 26;6(5):414-21. Epub 2015 Oct 26.

Department of Orthopaedics, Princess Alexandra Hospital, Brisbane, Australia.

Study Design: An international, multicenter cross-sectional image-based study performed in 33 institutions in the Asia Pacific region.

Objective: The study addressed the role of facet joint angulation and tropism in relation to L4-L5 degenerative spondylolisthesis (DS).

Methods: The study included 349 patients (63% females; mean age: 61.8 years) with single-level DS; 82 had no L4-L5 DS (group A) and 267 had L4-L5 DS (group B). Axial computed tomography and magnetic resonance imaging were utilized to assess facet joint angulations and tropism (i.e., asymmetry between facet joint angulations) between groups.

Results: There was a statistically significant difference between group A (left mean: 46.1 degrees; right mean: 48.2 degrees) and group B (left mean: 55.4 degrees; right mean: 57.5 degrees) in relation to bilateral L4-L5 facet joint angulations (p < 0.001). The mean bilateral angulation difference was 7.4 and 9.6 degrees in groups A and B, respectively (p = 0.025). A critical value of 58 degrees or greater significantly increased the likelihood of DS if unilateral (adjusted OR: 2.5; 95% CI: 1.2 to 5.5; p = 0.021) or bilateral facets (adjusted OR: 5.9; 95% CI: 2.7 to 13.2; p < 0.001) were involved. Facet joint tropism was found to be relevant between 16 and 24 degrees angulation difference (adjusted OR: 5.6; 95% CI: 1.2 to 26.1; p = 0.027).

Conclusions: In one of the largest studies assessing facet joint orientation in patients with DS, greater sagittal facet joint angulation was associated with L4-L5 DS, with a critical value of 58 degrees or greater increasing the likelihood of the condition for unilateral and bilateral facet joint involvement. Specific facet joint tropism categories were noted to be associated with DS.
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http://dx.doi.org/10.1055/s-0035-1564417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4947402PMC
August 2016

Is lumbar facet joint tropism developmental or secondary to degeneration? An international, large-scale multicenter study by the AOSpine Asia Pacific Research Collaboration Consortium.

Scoliosis Spinal Disord 2016 9;11. Epub 2016 Feb 9.

Department of Orthopaedics, University of Queensland, Brisbane, Australia.

Background: Facet joint tropism is asymmetry in orientation of the bilateral facets. Some studies have shown that tropism may increase the risk of disc degeneration and herniations, as well as degenerative spondylolisthesis (DS). It remains controversial whether tropism is a pre-existing developmental phenomena or secondary to progressive remodeling of the joint structure due to degenerative changes. As such, the following study addressed the occurrence of tropism of the lower lumbar spine (i.e. L3-S1) in a degenerative spondylolisthesis patient model.

Methods: An international, multi-center cross-sectional study that consisted of 349 patients with single level DS recruited from 33 spine institutes in the Asia Pacific region was performed. Axial MRI/CT from L3-S1 were utilized to assess left and right facet joint sagittal angulation in relation to the coronal plane. The angulation difference between the bilateral facets was obtained. Tropism was noted if there was 8° or greater angulation difference between the facet joints. Tropism was noted at levels of DS and compared to immediate adjacent and distal non-DS levels, if applicable, to the index level. Age, sex-type and body mass index (BMI) were also noted and assessed in relation to tropism.

Results: Of the 349 subjects, there were 63.0 % females, the mean age was 61.8 years and the mean BMI was 25.6 kg/m(2). Overall, 9.7, 76.5 and 13.8 % had L3-L4, L4-L5 and L5-S1 DS, respectively. Tropism was present in 47.1, 50.6 and 31.3 % of L3-L4, L4-L5 and L5-S1 of levels with DS, respectively. Tropism involved 33.3 to 50.0 % and 33.3 to 58.8 % of the immediate adjacent and most distal non-DS levels from the DS level, respectively. Patient demographics were not found to be significantly related to tropism at any level (p > 0.05).

Conclusions: To the authors' knowledge, this is one of the largest studies conducted, in particular in an Asian population, addressing facet joint tropism. Although levels with DS were noted to have tropism, immediate adjacent and distal levels with no DS also exhibited tropism, and were not related to age and other patient demographics. This study suggests that facet joint tropism or perhaps subsets of facet joint orientation may have a pre-disposed orientation that may be developmental in origin or a combination with secondary changes due to degenerative/slip effects. The presence of tropism should be noted in all imaging assessments, which may have implications in treatment decision-making, prognostication of disease progression, and predictive modeling. Having a deeper understanding of such concepts may further elaborate on the precision phenotyping of the facets and their role in more personalized spine care. Additional prospective and controlled studies are needed to further validate the findings.
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http://dx.doi.org/10.1186/s13013-016-0062-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4888515PMC
June 2016

Intraoperative implant rod three-dimensional geometry measured by dual camera system during scoliosis surgery.

Biomed Mater Eng 2016 May;27(1):49-62

Advanced Medicine for Spine and Spinal Cord Disorders, Graduate School of Medicine, Hokkaido University, North 15 West 7 North Ward, Sapporo, Japan 060-8638.

Treatment for severe scoliosis is usually attained when the scoliotic spine is deformed and fixed by implant rods. Investigation of the intraoperative changes of implant rod shape in three-dimensions is necessary to understand the biomechanics of scoliosis correction, establish consensus of the treatment, and achieve the optimal outcome. The objective of this study was to measure the intraoperative three-dimensional geometry and deformation of implant rod during scoliosis corrective surgery.A pair of images was obtained intraoperatively by the dual camera system before rotation and after rotation of rods during scoliosis surgery. The three-dimensional implant rod geometry before implantation was measured directly by the surgeon and after surgery using a CT scanner. The images of rods were reconstructed in three-dimensions using quintic polynomial functions. The implant rod deformation was evaluated using the angle between the two three-dimensional tangent vectors measured at the ends of the implant rod.The implant rods at the concave side were significantly deformed during surgery. The highest rod deformation was found after the rotation of rods. The implant curvature regained after the surgical treatment.Careful intraoperative rod maneuver is important to achieve a safe clinical outcome because the intraoperative forces could be higher than the postoperative forces. Continuous scoliosis correction was observed as indicated by the regain of the implant rod curvature after surgery.
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http://dx.doi.org/10.3233/BME-161572DOI Listing
May 2016