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Introduction: Surgical site infection (SSI) is one of the most serious postoperative complications following instrumented spinal surgery. We previously reported the potential of continuous local antibiotic perfusion (CLAP) to retain implants for patients with SSI following instrumented spinal surgery. We conducted a retrospective multicenter study to elucidate the efficacy and limitations of CLAP for patients with SSI following instrumented spinal surgery., Methods: A total of 40 patients treated with CLAP for SSI after instrumented spinal surgery were included in this study. The implant retention rate was calculated. We investigated the influence of age, presence of diabetes, number of fused vertebrae, causative pathogens, duration from diagnosis to CLAP initiation, white blood cell (WBC) count (× 10 3 /μL), and C-reactive protein (CRP) level on the development of SSI after CLAP. Patients were divided into two groups: a favorable outcome group (n = 28), in which SSI was promptly controlled after CLAP, and a poor outcome group (n = 12), in which additional surgery was required or fatal outcomes occurred after CLAP. The relationship between these two groups was evaluated., Results: In 13 of 40 patients, implants had already been removed before CLAP initiation. Excluding these cases, control of SSI with implant retention was achieved by CLAP in 22 of 27 patients (81%). In the poor outcome group, antibiotic-resistant pathogens were detected at a higher rate than in the favorable outcome group (p = 0.022), and the WBC counts at 1 week after CLAP were significantly increased compared with the favorable outcome group (poor outcome group 7.7 ± 2.4, favorable outcome group 5.8 ± 1.6; p = 0.013)., Conclusions: Application of CLAP enabled SSI control with a high rate of implant retention. However, detection of antibiotic-resistant pathogens and increased WBC count 1 week after initiating CLAP may predict poor control of SSI, even after CLAP., Competing Interests: Declarations. Conflict of Interests: All the authors, including Hiroshi Takahashi, Kohei Okuyama, Yasunori Toki, Toru Funayama, Hiroshi Noguchi, Kousei Miura, Hisanori Gamada, Shun Okuwaki, Yosuke Ogata, Kotaro Sakashita, Takahiro Sunami, Takane Nakagawa, Kengo Fujii, Tetsuhiro Ishikawa, Geundong Kim, Mitsutoshi Ota, Taigo Inada, Daisuke Himeno, Hiromitsu Takaoka, Masahiro Suzuki, Satoshi Maki, Masahiro Inoue, Kazuhide Inage, Yasuhiro Shiga, Takeo Furuya, Yawara Eguchi, Sumihisa Orita, Seiji Ohtori, Masashi Yamazaki, and Masao Koda, declare that there is no conflict of interest. Ethical Approval: The present study was approved by the ethics committees of the University of Tsukuba (Tsukuba Clinical Research & Development Organization, approval No. H30-087) and Ethics Committee of Chiba University School of Medicine (approval No. 2030). The study was conducted in accordance with the Helsinki Declaration of 1964 and its later amendments. Informed consent was obtained from all patients for the off-label use of gentamicin, participation in the study, publication of the study, and use of their data., (© 2025. The Author(s).)

Background Context: Menarche is widely recognized as one of the prognostic factors for curve progression in patients with adolescent idiopathic scoliosis (AIS). However, few studies focus on the relationship between small AIS curves without brace treatment and menarche, presenting a challenge to building further evidence., Purpose: This study aims to investigate the chronological changes in curve progression and risk of final brace initiation around menarche in small AIS curves under 25°., Study Design: This was a retrospective cohort study., Patient Sample: We longitudinally examined 1,090 AIS patients with a curve of less than 25° at the initial visit., Outcome Measures: Patients were followed up until they achieved skeletal maturity or initiated brace treatment., Methods: Curve progression based on time from menarche was analyzed using a t-test. Receiver operating characteristic curve analysis was performed based on the time from menarche, with curve magnitude as the independent variable and the final initiation of brace treatment as the dependent variable., Results: Overall, 1,090 female patients were included, with a mean initial visit age of 12.9 years (standard deviation [SD]: 1.5) and a mean coronal Cobb angle of 17.5° (SD: 4.3). Curve progression was significantly decreased between 0-1 and 1-2 years post-menarche (0-1 year post-menarche: 2.9°/year vs. 1-2 years post-menarche: 1.3°/year; p=.03). After 2 years from menarche, the mean curve progression was less than 0.4°/year. The cut-off value of the curve magnitude for the final initiation of brace treatment at the timing of menarche was 20.5° (area under the curve: 0.89, p<.001, 95% confidence interval: 0.86-0.91)., Conclusions: This study highlights that in small AIS curves under 25°, minimal curve progression was observed after 2 years post-menarche, aiding follow-up strategies for AIS conservative treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier Inc. All rights reserved.)

Background Massive blood loss is a major complication of posterior instrumented thoracolumbar surgery for adult spinal deformities. The use of flowable and absorbable hemostatic products, such as SURGIFLO ® Hemostatic Matrix (SURGIFLO; ETHICON, Inc., Raritan, NJ, US), has become feasible for spinal surgery. Hence, a retrospective observational study was conducted to evaluate the efficacy of SURGIFLO during posterior instrumented thoracolumbar spinal surgery for an adult spinal deformity. Methods This analysis included 36 consecutive patients who underwent posterior instrumented thoracolumbar spinal surgery for an adult spinal deformity at our hospital from 2018 to 2022. Patients were divided into two groups: 19 who received SURGIFLO after March 2020 (Group S) and 17 who did not receive SURGIFLO before March 2020 (Group C). Operation time, intraoperative blood loss, postoperative blood loss (calculated from the suction drain until the next morning), and the number of perioperative blood transfusions were investigated. Results No significant differences were found between groups in terms of the number of fusion levels, osteotomy grades, and average operative times. However, Group S showed significantly less intraoperative blood loss per intervertebral level compared with Group C (p=0.023). Although the amount of concentrated red cells used did not differ significantly between groups, Group S required significantly less perioperative fresh frozen plasma than Group C (p=0.021). Conclusion In patients with an adult spinal deformity undergoing posterior instrumented spinal surgery from the thorax to the pelvis, utilization of SURGIFLO Hemostatic Matrix reduced intraoperative blood loss and the perioperative use of fresh frozen plasma., Competing Interests: Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Tsukuba Clinical Research & Development Organization issued approval R06-110. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2025, Takahashi et al.)

Purpose: This study aimed to evaluate the difference in treatment duration and unplanned additional surgeries between patients with unidentified causative organisms on empiric antibiotics and those with identified organisms on selective antibiotics in treating thoracolumbar pyogenic spondylitis with minimally invasive posterior fixation., Methods: This multicenter retrospective cohort study included patients with thoracolumbar pyogenic spondylitis refractory to conservative treatment who underwent minimally invasive posterior fixation. Patients were divided into the identified (known causative organism) and unidentified groups (unknown causative organism). We analyzed data on demographics, antibiotic use, surgical outcomes, and infection control indicators., Results: We included 74 patients, with 52 (70%) and 22 (30%) in the identified and unidentified groups, respectively. On admission, the identified group had higher C-reactive protein (CRP) levels and more iliopsoas abscesses. The duration to postoperative CRP negative was similar in the identified and unidentified groups (7.13 vs. 6.48 weeks, p = 0.74). Only the identified group had unplanned additional surgeries due to poor infection control, affecting 6 of 52 patients (12%). Advanced age and causative organism identification increased the additional surgery odds (odds ratio [OR], 8.25; p = 0.033 and OR, 6.83; p = 0.034, respectively)., Conclusion: The use of empiric antibiotics in minimally invasive posterior fixation was effective without identifying the causative organism and did not prolong treatment duration. In patients with identified organisms, 12% required unplanned additional surgery, indicating a more challenging infection control. Causative organism identification was associated with the need for additional surgery, suggesting a more cautious treatment strategy for these patients., Competing Interests: Declarations. Competing interests: The authors have no competing interests to declare that are relevant to the content of this article. Informed consent: Written informed consent was obtained from all patients and their parents for the publication of this study. Ethical approval: The institutional review board of Ibaraki Western Medical Center (protocol code No. 21 − 07, approved on January 27, 2022) approved all procedures, including the review of patient records. All procedures were performed in accordance with the Declaration of Helsinki. All patients provided written informed consent. The IRB approved the procedures outlined for obtaining consent for this study., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: A standard 6-12-week course of antibiotics is recommended for pyogenic spondylitis. Recent evidence supports early minimally invasive posterior fixation surgery; however, its effect on antibiotic treatment duration is unclear. This study aims to identify factors associated with prolonged antibiotic treatment in thoracolumbar pyogenic spondylitis patients resistant to conservative treatment and assess whether early surgery can reduce treatment duration., Methods: We retrospectively reviewed 74 patients with thoracolumbar pyogenic spondylitis undergoing minimally invasive posterior fixation at nine facilities. Patients were grouped based on antibiotic duration (≥ 6 or < 6 weeks) and timing of surgery (≤ 3 weeks or > 3 weeks of starting antibiotics). Univariable and multivariable logistic regression analyses were used to identify factors associated with prolonged antibiotic treatment and study the outcomes of patients undergoing early surgery., Results: Forty-nine patients (66%) required prolonged antibiotic treatment. The presence of an iliopsoas abscess (p = 0.0006) and elevated C-reactive protein (CRP) levels (≥ 10 mg/dL, p = 0.015) were independently associated with prolonged antibiotic treatment. Early surgery significantly reduced total antibiotic duration (5.3 weeks vs. 9.9 weeks, p < 0.0001) without increasing the incidence of postoperative infection recurrences and unplanned additional surgeries. Despite factors associated with prolonged antibiotic treatment, early surgery consistently shortened the treatment duration compared to late surgery., Conclusions: Early surgery (within three weeks) with minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis is associated with reduced antibiotic duration and overall treatment duration regardless of the presence of prolonging factors like iliopsoas abscess and elevated CRP levels., Competing Interests: Declarations. Ethical approval: The institutional review board of Ibaraki Western Medical Center (protocol code No. 21 − 07, approved on January 27, 2022) approved all procedures, including the review of patient records. All procedures were performed in accordance with the Declaration of Helsinki. All patients provided written informed consent. The IRB approved the procedures outlined for obtaining consent for this study. Competing interests: The authors have no competing interests to declare that are relevant to the content of this article., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Patients with residual adolescent idiopathic scoliosis (AIS) and thoracolumbar/lumbar curves may present with progression after cessation of growth, with lateral translation as a major risk factor. Nonetheless, radiographic predictors and underlying mechanisms remain indefinite. This study aimed to determine these radiographic predictors and structural mechanisms in patients with residual AIS., Methods: Radiographic and clinical data were collected from 45 consecutive patients with preoperative residual AIS and thoracolumbar/lumbar Cobb angle >40° who subsequently underwent corrective surgery at our institution. Lateral translation was defined as intervertebral slippage ≥6 mm on computed tomography. Statistical analyses included Student's t-test, Pearson's correlation coefficients, receiver operating characteristic curve analysis, and multivariate logistic regression analysis., Results: Of 45 patients, 3 were male, whereas 42 were female, with a mean age of 40.6 ± 17.4 years. L3 slippage was observed in 21 patients, resulting in the categorization into the slippage and nonslippage cohorts. Multivariate logistic regression analysis revealed statistically significant disparities in the bilateral facet angles, facet joint opening, and facet joint vacuum phenomenon between the 2 cohorts. The receiver operating characteristic analysis determined a 20.5° cut-off value for predicting L3 slippage. In the nonslippage cohort, a strong correlation was particularly observed between L3 slippage and L2-L3 bridging., Conclusions: Facet joint instability, L4 tilt ≥20.5°, and L3 cranial vertebral bridging are predictive radiographic factors for L3 lateral translation in patients with residual AIS. Thus, patients exhibiting these characteristics require consistent follow-up or early surgical intervention before lateral translation occurs., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Although neurovascular structures, including the superior gluteal artery, sciatic nerve, obturator nerve, internal iliac vein and artery, and lumbosacral plexus, are at risk when S2 alar-iliac (S2AI) screws are used, no cases of nerve injuries have been reported. An 84-year-old man was referred to our institute with persistent left sciatica for seven months after undergoing salvage surgery using S2AI screws for deep surgical site infection from a previous posterior interbody fusion surgery at L5-S1. Based on the radiographic and diagnostic selective nerve root block findings, a diagnosis of left L5 radiculopathy was suspected due to the left S2AI screw being caudally misplaced and severely protruding into the pelvic cavity. The patient underwent surgical replacement of the left S2AI screw. The patient was discharged eight days postoperatively, with a resolution of the left leg pain. At the three-month follow-up, no recurrent pain was reported. To the best of our knowledge, this is the first reported case of a misplaced S2AI screw causing L5 spinal nerve injury. If the screw is inserted caudally and deviates into the pelvic cavity, in front of the sacroiliac joint, the L5 nerve running in this region may be damaged., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Funayama et al.)

Purpose: The crankshaft phenomenon (CSP) is a corrective loss after posterior surgery for early onset scoliosis (EOS). However, an accurate method for CSP evaluation has yet to be developed. In this study, we evaluated pedicle screw (PS) length and rotation angle using an inverse trigonometric function and investigated the prevalence of the CSP., Methods: Fifty patients from nine institutions (mean age 10.6 years, male/female ratio 4:46) who underwent early definitive fusion surgery at ≤ 11 years of age were included. The rotation angle was calculated as arctan (lateral/frontal PS length) using radiography. Measurements were taken at the apex and lower instrumented vertebra (LIV) immediate, 2-, and 5-year postoperatively. CSP was defined as a rotation angle progression ≥ 5°. We divided patients into CSP and non-CSP groups and measured the demographic parameters, Risser grade, state of the triradiate cartilage, major coronal Cobb angle, T1-T12 length, T1-S1 length, and presence of distal adding-on (DAO). We compared these variables between groups and investigated the correlation between the measured variables and vertebral rotation. Logistic regression analysis investigated factors associated with CSP., Results: The rotation angle progressed by 2.4 and 1.3° over 5 years for the apex and LIV, respectively. CSP occurred in 15 cases (30%), DAO in 11 cases (22%), and CSP and DAO overlapped in 4 cases (8%). In the CSP group, the T1-T12 length was low immediate postoperatively. The rotation angle was negatively correlated with preoperative height (r = - 0.33), T1-T12 length (r = - 0.35), and T1-S1 length (r = - 0.30). A lower preoperative T1-T12 length was associated with CSP (odds ratio: 0.996, p = 0.048)., Conclusions: CSP occurred in 30% of patients with EOS who underwent definitive fusion. The presence of CSP was associated with a lower preoperative T1-T12 length., Level of Evidence: Diagnosis, level IV., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Background: The current study aimed to evaluate the bone union rate between infected vertebrae after minimally invasive posterior fixation without bone grafting in thoracolumbar pyogenic spondylitis., Methods: This retrospective multicenter cohort study evaluated 75 patients of posterior fixation for thoracolumbar pyogenic spondylitis that have been recorded at six relevant institutions from January 2016 to December 2022. Data on age, sex, location of infected vertebrae, number of infected disks, comorbidity, Pola classification, number of vertebrae fixed according to surgery, implant failure requiring revision surgery, and distance according to the type of infected vertebrae after surgery were evaluated. Further, their association with postoperative bone union was investigated > 12 months postoperatively., Results: Finally, 40 patients were included in the study. In total, 32 (80%) patients achieved bone union at the infected vertebrae after minimally invasive posterior fixation without bone grafting. The mean duration from surgery to union was 10.7 months. Twenty-six (65%) patients initially achieved bone union at the lateral and/or anterior bridging callus. Patients with multiple-level infected disks (33%, 2/6 patients) had a lower bone union rate than those with a single-level infected disk (88%, 30/34 patients) (p = 0.0095)., Conclusions: In 80% of patients, bone union at the infected vertebrae was achieved after minimally invasive posterior fixation without bone grafting in thoracolumbar pyogenic spondylitis. A total of 65% of the patients achieved initial bone union at the lateral and/or anterior bridging callus. Moreover, patients with multiple-level infected disks had a low bone union rate. Hence, the treatment strategy should be cautiously considered., Trial Registration: This study was registered retrospectively and all procedures used in this study including the review of patient records were approved by the institutional review board., (© 2024. The Author(s).)

Assessing intraoperative hemodynamics with Surgical Apgar Score (SAS) and preoperative nutritional status with the Controlling Nutritional Status (CONUT) score are said to be useful to predict postoperative complications in many surgical services, but little is reported in the field of spinal surgery. The purpose of this study was to assess the utility of SAS and the CONUT score for predicting the risk of major postoperative complications after spinal surgery. We included 659 people who undergone spinal surgery in our institute in eight consecutive years. The occurrence of postoperative major complications was investigated. Background clinical information, surgical information including the SAS and the CONUT score, and the length of postoperative hospital stay were collected. The risk factors of postoperative complications were assessed statistically. Complications occurred in 117 cases (17.8%). The multivariate analysis showed that history of diabetes mellitus (odds ratio [OR] 1.81: P = 0.035), coronary disease (OR 3.33; P = 0.009), American Society of Anesthesiologists Physical Status (OR 1.71; P = 0.025), use of instruments (OR 2.07; P = 0.026), operation time (OR 1.30; P < 0.001), SAS (OR 0.59; P < 0.001), and CONUT (OR 1.34; P < 0.001) were independent risk factors of major complications after spinal surgery. Assessing the intraoperative hemodynamics with SAS and preoperative nutritional status with the CONUT score was useful in predicting major postoperative complications after spinal surgery. People who are detected as high risked people should be managed carefully after spinal surgery., (© 2024. The Author(s).)

Background: Proximal femoral fractures in geriatric patients are a major challenge in orthopedics, often leading to major functional impairment. Early surgical intervention is crucial for improving patient recovery and overall health outcomes. Thus, Japan's Ministry of Health, Labour and Welfare initiated a reimbursement policy in April 2022 to encourage early surgery for these fractures in patients aged ≥75 years. This study investigated the impact of this policy on early surgery rates in Japan and identified factors influencing the timing of surgical interventions., Methods: We retrospectively analyzed the data of patients who underwent surgery for proximal femoral fractures at our institution between April 2022 and March 2023. Patients were categorized into two groups based on the timing of surgery relative to the injury: ≤48 h and >48 h. Demographic and clinical data, including age, sex, fracture type, and various health- and admission-related factors, were assessed., Results: Of the 192 patients, 152 were included in the study. Among them, 38% underwent early surgery (≤48 h), and 15% of the patients arrived more than 48 h post-injury. Significant differences were found in admission routes and residence types between the groups. The ≤48 h group had shorter intervals from injury to admission and surgery than the >48 h group. Factors such as the admission process, day of the week, and C-reactive protein levels significantly influenced the timing of surgery., Conclusions: After introducing incentives for early surgery in Japan, 38% of patients with proximal femoral fractures underwent surgery within 48 h of injury. Factors contributing to patients not receiving early surgery included transport from another hospital, weekend hospitalization, and elevated CRP levels. These findings suggest that achieving surgery within 48 h of injury is challenging through hospital efforts alone, and the time criteria might be more appropriate if changed to "admission to surgery.", Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Study Design: A post-hoc analysis of a prospective cohort study., Purpose: This study aimed to identify factors at the time of injury associated with declining activities of daily living (ADLs) in the chronic phase of osteoporotic vertebral fractures (OVFs) managed conservatively., Overview of Literature: Although a conservative approach is the treatment of choice for OVFs, ADLs do not improve or eventually decrease in some cases. However, the risk factors for ADL decline after the occurrence of OVFs, particularly the difference between those with or without initial bed rest, are unknown., Methods: A total of 224 consecutive patients with OVFs aged ≥65 years who received treatment within 2 weeks after the occurrence of injury were enrolled. The patients were followed up for 6 months thereafter. The criteria for evaluating the degree of independence were applied to evaluate ADLs. Multivariable analysis with a logistic regression model was performed to evaluate the risk factors for ADL decline., Results: In total, 49/224 patients (21.9%) showed a decline in ADLs. Of these, 23/116 patients (19.8%) in the rest group and 26/108 patients (24.1%) in the no-rest group experienced a decline in ADLs. In the logistic regression analyses, a diffuse low signal on T2- weighted magnetic resonance imaging (MRI) (odds ratio, 5.78; 95% confidence interval, 2.09-16.0; p=0.0007) and vertebral instability (odds ratio, 3.89; 95% confidence interval, 1.32-11.4; p=0.0135) were identified as independent factors in the rest and no-rest groups, respectively., Conclusions: In patients with acute OVFs, a diffuse low signal on T2-weighted MRI and severe vertebral instability were independently associated with ADL decline in patients treated with and without initial bed rest, respectively.

Study Design: A single-center retrospective cohort study., Objectives: To develop a predictive scoring system for bone union after conservative treatment of lumbar spondylolysis and assess its internal validity., Summary of Background Data: Lumbar spondylolysis, a common stress fracture in young athletes, is typically treated conservatively. Predicting bone union rates remains a challenge., Methods: This study included patients aged ≤18 years with lumbar spondylolysis undergoing conservative treatment. A multivariable logistic regression analysis was used to develop a scoring system containing six factors: sex, age, lesion level, main side stage of the lesion, contralateral side stage of the lesion, and spina bifida occulta. The predictive scoring system was internally validated from the receiver operating characteristic (ROC) curve using bootstrap methods., Results: The final analysis included 301 patients with 416 lesions, with an overall bone union rate of 80%. On multivariable analysis, the main and contralateral stages were identified as factors associated with bone union. The predictive scoring system was developed from the main side stage score (prelysis, early=0, progressive stage=1) and the contralateral side stage score (none=0, prelysis, early, progressive stage=1, terminal stage=3). The area under the curve was 0.855 (95% confidence interval: 0.811-0.896) for the ROC curve, showing good internal validity. The predicted bone union rates were generally consistent with the actual rates., Conclusions: A simple predictive scoring system was developed for bone union after conservative treatment of lumbar spondylolysis, based on the stage of the lesion on the main and contralateral sides. The predicted bone union rate was approximately 90% for a total score of 0-1 and ≤30% for a score of 3-4. This system demonstrated good internal validity, suggesting its potential as a useful tool in clinical decision making for the management of spondylolysis., Competing Interests: Conflict of Interest and Source of Funding: The authors received no financial or material support for the research, authorship, and publication of this article. The authors did not receive support from any organization for the submitted work., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Minimally invasive posterior fixation surgery for pyogenic spondylitis is known to reduce invasiveness and complication rates; however, the outcomes of concomitant insertion of pedicle screws (PS) into the infected vertebrae via the posterior approach are undetermined. This study aimed to assess the safety and efficacy of PS insertion into infected vertebrae in minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis., Methods: This multicenter retrospective cohort study included 70 patients undergoing minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis across nine institutions. Patients were categorized into insertion and skip groups based on PS insertion into infected vertebrae, and surgical data and postoperative outcomes, particularly unplanned reoperations due to complications, were compared., Results: The mean age of the 70 patients was 72.8 years. The insertion group (n = 36) had shorter operative times (146 versus 195 min, p = 0.032) and a reduced range of fixation (5.4 versus 6.9 vertebrae, p = 0.0009) compared to the skip group (n = 34). Unplanned reoperations occurred in 24% (n = 17) due to surgical site infections (SSI) or implant failure; the incidence was comparable between the groups. Poor infection control necessitating additional anterior surgery was reported in four patients in the skip group., Conclusions: PS insertion into infected vertebrae during minimally invasive posterior fixation reduces the operative time and range of fixation without increasing the occurrence of unplanned reoperations due to SSI or implant failure. Judicious PS insertion in patients with minimal bone destruction in thoracolumbar pyogenic spondylitis can minimize surgical invasiveness., (© 2024. The Author(s).)

Spondylolysis with pseudarthrosis may be treated surgically by repairing the spondylolysis using the smiley face rod (SFR) technique. The SFR technique can avoid adjacent segmental disease caused by transforaminal lumbar interbody fusion (TLIF), which is one of the main surgical techniques to treat isthmic lumbar spondylolisthesis. A 59-year-old woman had been playing softball since she was 12 years old and was a member of a prefectural representative team. She sought treatment because of numbness in her left lower limb and difficulty playing softball. Despite conservative treatment for a year, her symptoms did not improve. Physical examination revealed decreased patellar tendon reflexes and numbness and pain from the front of the thigh to the lower leg without muscle weakness. Imaging showed L4 isthmic spondylolisthesis with Meyerding classification grade 2 anterior slip and L5 spondylolysis with pseudarthrosis. We diagnosed L4 radiculopathy caused by L4/5 foraminal stenosis and L4 isthmic spondylolisthesis with L5 spondylolysis. She underwent surgery combining the TLIF of L4/5 and the SFR technique of L5 using dual-headed pedicle screws that can fix two types of rods with L5 pedicle screws. Three months after surgery, fusion between L4/5 and fusion of the L5 pars cleft were confirmed. She resumed sports, and one year postoperatively, she was able to participate in softball games. Two years postoperatively, she could bat, run, and play defense without adjacent segmental disease. Two-segment TLIF increases adjacent segmental disease more than single-segment TLIF. Because the L5 spondylolysis had not slipped, we chose the SFR technique to preserve mobility at L5/S1. The dual-headed pedicle screw fastens two-type rods at the head of the pedicle screw, making it a suitable design for this procedure., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Tatsumura et al.)

Introduction: Disc degeneration is a risk factor of pyogenic spondylitis. However, its degree in patients with pyogenic spondylitis is unknown. This study aimed to determine differences in disc degeneration between patients with pyogenic spondylitis and those with noninfectious lumbar spondylosis., Methods: A total of 85 patients with lumbar pyogenic spondylitis (the infected group) and 156 with lumbar spondylosis who underwent posterior lumbar interbody fusion (the noninfected group) were retrospectively evaluated. Patients with a previous history of spinal fusion, tuberculous spondylitis, and multilevel infection and those receiving dialysis were excluded. Magnetic resonance imaging of the lumbar spine was conducted. Each disc at the L1/2-L5/S levels was graded. The total score of the four discs, excluding the affected disc, was used as the modified disc degenerative disease (DDD) score. Propensity score matching was performed using independent variables such as age, sex, diabetes mellitus, cancer, and steroid use. The modified DDD scores at all and each disc level were compared between the two matched groups., Results: After matching, 48 patients in the infected group and 88 in the noninfected group were finally included in the study. The mean modified DDD scores of the infected and noninfected groups were 7.63 and 5.40, respectively. The modified DDD scores at all and each disc level were higher in the infected group than in the noninfected group., Conclusions: The incidence of disc degeneration at all and each disc level was higher in patients with pyogenic spondylitis than in those with noninfectious lumbar spondylosis., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2024 The Japanese Society for Spine Surgery and Related Research.)

Background: Adolescent idiopathic scoliosis (AIS) causes vertebral wedging, but associated factors and the impact of vertebral wedging are still unknown. We investigated associated factors and effects of vertebral wedging in AIS using computed tomography (CT)., Methods: Preoperative patients (n = 245) with Lenke types-1 and 2 were included. Vertebral wedging, lordosis, and rotation of the apical vertebra were measured by preoperative CT. Skeletal maturity and radiographic global alignment parameters were evaluated. Multiple regression analysis was performed on associated factors for vertebral wedging. Side-bending radiographs were evaluated using multiple regression analysis to calculate the percentage of reduction of Cobb angles to determine curve flexibility., Results: The mean vertebral wedging angle was 6.8 ± 3.1°. Vertebral wedging angle was positively correlated with proximal thoracic (r = 0.40), main thoracic (r = 0.54), and thoracolumbar/lumbar curves (r = 0.38). By multiple regression, the central sacral vertical line (p = 0.039), sagittal vertical axis (p = 0.049), main thoracic curve (p = 0.008), and thoracolumbar/lumbar curve (p = 0.001) were significant factors for vertebral wedging. In traction and side-bending radiographs there were positive correlations between curve rigidity and the vertebral wedging angle (r = 0.60, r = 0.59, respectively). By multiple regression, thoracic kyphosis (p < 0.001), lumbar lordosis (p = 0.013), sacral slope (p = 0.006), vertebral wedging angle (p = 0.003), and vertebral rotation (p = 0.002) were significant factors for curve flexibility., Conclusions: Vertebral wedging angle was found to be highly correlated to coronal Cobb angle, with larger vertebral wedging indicating less flexibility., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Study Design: A retrospective, cross-sectional study was conducted to analyze the implications of asymmetric baseball movements on the incidence of spondylolysis., Purpose: This study aimed to evaluate the relationship between asymmetric movements and the laterality of spondylolysis., Overview of Literature: Baseball, characterized by its asymmetric throwing and batting, may disproportionately stress one side. Lumbar spondylolysis is a frequent cause of lower back pain in young athletes, particularly those involved in activities with consistent unilateral rotations such as baseball. However, whether a link exists between the laterality in spondylolysis and the dominant throwing/ batting side or whether disparities exist between pitchers and fielders remains unclear., Methods: The study included 85 players. Participants were divided into two groups: pitchers and fielders. The association between the laterality of spondylolysis and the throwing/batting side in the overall cohort and between the two groups was evaluated., Results: Among pitchers, 16 lesions appeared on the throwing side and 32 on the nonthrowing side (p =0.029). For fielders, no notable difference was observed between the two sides (p =0.363). Furthermore, batting preference did not influence the laterality of spondylolysis in either group., Conclusions: Adolescent baseball players, particularly pitchers, exhibited a higher incidence of lumbar spondylolysis on the side opposite their throwing arm. The findings of this study highlight the significant effect of asymmetrical sporting activities on the development of spondylolysis, to which pitchers are particularly susceptible.

Introduction This research aimed to explore the relationship between spinal characteristics and the length of the abdominal aorta in adult spinal deformity (ASD) patients who underwent corrective spinal surgery. We hypothesized that adjusting spinal alignment might affect the abdominal aorta's length. Methods This study included thirteen patients with ASD (average age: 63.0 ± 8.9 years; four males and nine females) who received spinal correction surgery. We measured both pre-operative and post-operative spinal parameters, including thoracolumbar kyphosis (TLK), and calculated their differences (Δ). The length of the aorta (AoL) was determined using an automated process that measures the central luminal line from the celiac artery's bifurcation to the inferior mesenteric artery. This measurement was made using contrast-enhanced computed tomography for three-dimensional aortic reconstruction. We compared the pre-operative and post-operative AoLs and their differences (Δ). The study examined the correlation between changes in spinal parameters and changes in AoL. Results Post-operatively, there was an increase in aortic length (ΔAoL: 4.2 ± 4.9 mm). There was a negative correlation between the change in TLK and the change in AoL (R 2 = 0.45, p = 0.012, β = -0.21). No significant correlations were found with other spinal parameters. Conclusions The abdominal aorta can elongate by 4.8% after spinal corrective surgery in patients with ASD. The degree of elongation of the abdominal aorta is associated with spinal alignment correction., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Ohyama et al.)

Purpose: This study was designed to reveal the association between spinal parameters and RCS area in patients with adult spinal deformities treated with spinal correction surgery. We hypothesized that reduction of the retrocrural space (RCS) area is related to thoracolumbar alignment, which may cause acute celiac artery compression syndrome (ACACS)., Methods: Eighty-nine patients (age: 68.4 ± 7.6 years; sex: 7 male/82 female) with ASD treated by spinal correction surgery were enrolled. Preoperative and postoperative spinal parameters were measured, and the differences between these parameters were calculated. Postoperative T12 translation was measured and RCS area was evaluated using reconstructed computed tomography. The change of RCS area after surgery was defined as ΔRCS. Patients were divided into increased and decreased RCS groups by the ΔRCS value, and spinal parameters were compared between groups. The correlation between spinal parameters and ΔRCS was calculated., Results: The patients in the decreased RCS group had greater anterior T12 translation than those in the increased RCS group (p < 0.001). T12 translation was significantly correlated with ΔRCS (β = -0.31, p = 0.017). There were no correlations between ΔRCS and other spinal parameters., Conclusion: Thoracolumbar alignment was associated with RCS area. Consistent with the hypothesis, overcorrection of the thoracolumbar junction was associated with reduced RCS area and might be one risk factor for ACACS., Competing Interests: Conflicts of interest None., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Fifth lumbar vertebra (L5) spondylolysis has a lower bone union rate than non-L5 spondylolysis, but the reason for this is unknown. This study aimed to evaluate the differences in patient and lesion characteristics between L5 and non-L5 spondylolysis., Methods: A total of 410 patients with lumbar spondylolysis aged 18 years or younger who were treated conservatively were enrolled. Patients and lesions were divided into L5 and non-L5 (L2-L4) spondylolysis. Factors, including sex, age, presence of spina bifida occulta, stage of the main side lesion, whether the lesion was unilateral or bilateral, presence and stage of the contralateral side lesion and treatment duration, were evaluated at the first visit and compared between the two groups., Results: A total of 250 patients with 349 lesions were included. The bone union rate of L5 lesions was lower than that of non-L5 lesions (75% vs. 86%, p = 0.015). Patients with L5 spondylolysis were more likely to be male (86% vs. 66%) and younger (14.0 vs. 14.6 years) than patients with non-L5 spondylolysis. Lesions of L5 spondylolysis were more likely to be in a progressive stage (28% vs. 15%), less likely to be in a pre-lysis stage (28% vs. 43%) and more likely to be in a contralateral terminal stage (14% vs. 5.3%, p = 0.013) compared with lesions of non-L5 spondylolysis., Conclusions: L5 spondylolysis was characterised by a lower bone union rate, more males, younger age, more progressive stage and more contralateral pseudarthrosis than non-L5 spondylolysis., (© 2024. The Author(s).)

Objective: The first sacral nerve root block (S1 NRB) is used to diagnose and treat lumbosacral and radicular pain. This study aims to clarify the anatomy of the S1 neural foramen using three-dimensional (3D) computed tomography (CT) images and to establish the optimal fluoroscopic angle, localize the S1 neural foramen on fluoroscopy, and determine the safe puncture depth for S1 NRB., Methods: In this single-center cohort study, 200 patients with lumbar degenerative disease who underwent preoperative CT were enrolled. Four distinct studies were conducted using the CT data. Study 1 examined the correlation of the sacral slope angle and the supine and prone positions. Study 2 analyzed the tunnel view angle (TVA) using 3D reconstruction. Study 3 ascertained the location of the S1 neural foramen in fluoroscopy images. Study 4 investigated the safe depth for performing S1 NRB., Results: The regression analysis in Study 1 revealed a correlation of the sacral slope angle and the supine and prone positions. Study 2 determined an optimal fluoroscopic TVA of approximately 30° for the S1 NRB. Study 3 found that the S1 neural foramen was located caudal to the L5 pedicle 1.7 ± 0.2 times the distance between the L4 and L5 pedicles. Study 4 revealed that the depths of the S1 neural foramen and root were 27.0 ± 2.1 mm and 16.5 ± 2.0 mm, respectively., Conclusions: Our study suggests an optimal fluoroscopic angle, a simple method to locate the S1 neural foramen on fluoroscopy, and an ideal puncture depth for a safe and effective S1 NRB., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: This study aimed to determine the incidence and potential risk factors of superior mesenteric artery syndrome (SMAS) after corrective spinal surgery in patients with adult spinal deformity (ASD)., Methods: In total, 102 patients (67.6 ± 8.4 years; 8 male/94 female; body mass index (BMI); 22.4 ± 3.6 kg/m 2 ) with ASD treated by spinal correction surgery were enrolled. Preoperative and postoperative spinal parameters, including thoracolumbar kyphosis (TLK: T10-L2) and upper lumbar lordosis (ULL: L1-L4) were measured. To evaluate the potential risk factors of SMAS, the angle and the distance between the superior mesenteric artery and aorta, the aortomesenteric angle (AMA) and aortomesenteric distance (AMD), were evaluated pre- and postoperatively. Based on the postoperative AMA, AMD, and abdominal symptoms, the patients were diagnosed with SMAS. Correlations between demographic data or spinal parameters and AMA and AMD were assessed., Results: Two (2.0%) patients were diagnosed with SMAS. Postoperative TLK significantly correlated with postoperative AMA (P = 0.013, 0.046). Postoperative ULL was significantly correlated with postoperative AMD (β = -0.27; P = 0.014)., Conclusion: The incidence of SMAS after corrective spinal surgery in patients with ASD was 2.0%. Postoperative smaller TLK and greater ULL can be risk factors for developing SMAS. Spine surgeons should avoid overcorrection of the upper lumbar spine in the sagittal plane to prevent SMAS., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Introduction: Conventional methods for analyzing vertebral rotation are limited to postoperative patients who underwent posterior fusion. A previous methodology calculated vertebral rotation using inverse trigonometric functions based on the length of the pedicle screw (PS). Accordingly, this study evaluates rotational deformity in patients with postoperative adolescent idiopathic scoliosis (AIS) using inverse trigonometric functions., Methods: This retrospective single-center study includes patients with AIS who underwent posterior fusion surgery. Postoperative radiography and computed tomography (CT) scans were retrospectively evaluated. The magnification ratio was calculated using the rod diameter (δ=lateral/frontal rod diameter), and the visible screw lengths were measured using radiographs. The rotation angle was calculated using the apex of the main curve and the lower instrumented vertebra (LIV) (rotation angle=tan -1 (lateral PS length/(δ×frontal PS length))) immediately following the surgery as well as two and five years postoperatively. The correlation between the direct CT measurement and postoperative rotation angle progression was investigated. The crankshaft phenomenon (CSP) and distal adding-on (DAO) were evaluated as postoperative deformities. CSP was defined as a 5° increase in rotation angle., Results: Seventy-eight patients (age: 15.3±2.0 years, eight boys and seventy girls) were included. The rotation angle was strongly correlated with CT rotation measurements (r=0.87). The mean rotation angle at the apex and LIV did not change within five years postoperatively (mean: 0.5±3.6° and 0.4±3.4°, respectively). CSP and DAO were observed in 6.4% and 3.8% of patients, respectively., Conclusions: The inverse trigonometric method is useful to quantitatively evaluate the postoperative rotation angle and identify CSP., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2024 The Japanese Society for Spine Surgery and Related Research.)

Background: Ischemic necrosis of the abdominal organs caused by compression of the celiac artery (CA) and superior mesenteric artery (SMA) by the median arcuate ligament (MAL) after correction surgery has been recognized as acute celiac artery compression syndrome (ACACS). Here, using contrast-enhanced computed tomographic (CT) images, we sought to determine the prevalence and degree of CA and SMA stenosis in spinal patients preoperatively, and the risk factors associated with the stenosis., Methods: We retrospectively examined contrast-enhanced abdominal CT of 90 patients with preoperative lumbar degenerative disease, lumbar burst fracture, or adult spinal deformity. The trunks of the CA and SMA were detected using three-dimensional reconstructed CT. To investigate their degree of stenosis, we determined the ratio of the narrowest diameter of the stenotic segment to the distal normal lumen's diameter. Patients with a degree of stenosis ≥35% were defined as being in the group with stenosis and the remainder as in the group without. To determine the risk factors for stenosis of these arteries, the relationship between the stenosis and CA and SMA calcification or the median arcuate ligament (MAL) crossing the proximal portion of the celiac axis (MAL overlap) was also investigated., Results: The average degree of stenosis of the CA trunk was 12.1% ± 13.9% and that for the SMA trunk was 8.5% ± 8.8%. There were 8 patients (8.9%) in the group with CA stenosis and 2 patients (2.2%) in the group with SMA stenosis. The number of patients in the group with CA stenosis was significantly greater than the number with MAL overlap or CA calcification (P < 0.05)., Discussion: The prevalence of CA or SMA stenosis was 11.2% of preoperative patients due to undergo thoracolumbar fusion surgery. Calcifications of the CA trunk and MAL overlap are risk factors for CA stenosis., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare. No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript., (Copyright © 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Introduction: Lateral lumbar interbody fusion (LLIF) techniques have been extensively used in adult spinal deformity surgery. Preoperative knowledge of the optimal position of the patient on the surgical table is essential for a safe procedure. Therefore, this study aims to determine the optimal angle for positioning the patient on the surgical table during LLIF using three-dimensional computed tomography (3DCT)., Methods: Data from 59 patients (2 males, 57 females, mean age 66.3±8.6 years) with adult spinal deformities treated by performing corrective spinal surgery were included in this observational retrospective study. Simulated fluoroscopic images were obtained using 3DCT images rotated from the reference position with the spinous process of S1 as the midline to the position with the spinous process in the center of the bilateral pedicle of T12-L5. The rotation angle of each vertebra was measured and defined as the optimal rotation angle (ORA). The angle that bisected the angle between the maximum and minimum ORA was defined as the optimal mean angle of the maximum and minimum ORA (OMA) and considered the optimal angle for the patient's position on the surgical table, as this position could minimize the rotation angle of the surgical table during surgery. A multiple regression analysis was performed to predict OMA., Results: Multiple regression analysis revealed the following equation: OMA=1.959+(0.238×lumbar coronal Cobb angle)+(-0.208×sagittal vertical axis)., Conclusions: When the patient is placed on the surgical table by rotating them at the OMA, the rotation of the surgical table can be reduced, ensuring a safe and efficient surgical procedure., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2024 The Japanese Society for Spine Surgery and Related Research.)

Introduction: The smiley face rod method is an effective treatment for symptomatic terminal-stage spondylolysis. However, the risk factors for treatment failure are unknown. We investigated the association of pars defect type with the treatment outcomes of this method., Methods: We retrospectively examined data from 34 patients (18.0±6.7 years) with terminal-stage spondylolysis who underwent surgery using the smiley face rod method. The mean follow-up period was 44.9±21.4 months. The patients were divided into 2 groups: pars defect without bone atrophy or sclerosis (group A; 18 patients), and with bone atrophy and sclerosis (group B; 16 patients). We evaluated and compared the visual analog scale (VAS) score for back pain, bone union rate, and time to return to preinjury athletics level between the groups. Fisher exact and paired t tests were used to compare the variables between groups. The VAS score between the groups was compared using a 2-factor repeated-measures analysis of variance., Results: Within groups, the VAS score was significantly different over time ( p <0.001). The VAS scores between groups were not significantly different. Patients in group A had a significantly higher bone union rate per pars at 6 months (group A, 65.7%; and group B, 37.5%, p =0.028) and 24 months after surgery (group A, 97.1%; and group B, 75.0%, p =0.011). All patients returned to their respective sports, and no significant differences were observed in the time to return to preinjury athletics level between the groups ( p =0.055)., Conclusions: The type of pars defect are associated with bone union after the smiley face rod method, but have little effect on postoperative symptoms., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2024 The Japanese Society for Spine Surgery and Related Research.)

We report a case of vertebral fracture in a patient with rod fractures after adult spinal deformity surgery, which occurred at the same level as the rod fractures, even though intervertebral bone fusion in the fusion range had been achieved. A 77-year-old female underwent corrective spinal surgery for adult spinal deformity from T12 to the pelvis but had a subsequent uppermost instrumented vertebral fracture, resulting in pseudarthrosis and severe kyphosis. The patient underwent proximal fusion extension to the T4, which improved alignment. A right-sided rod fracture at the lumbosacral junction occurred after 18 months; however, it showed no symptoms. After a month, the patient experienced severe low back pain with left leg pain and was diagnosed with bilateral rod fractures associated with L5 hyperextension vertebral fracture. The patient underwent revision surgery to repair the fractured rods with a multiple-rod construct. Rod fractures can occur even when bone fusion is achieved within the fusion range. When rod fractures are detected at the lumbosacral junction even if the interbody fusion was achieved, a hyperextension vertebral fracture may occur., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Okuwaki et al.)

Background: Lumbar spondylolysis, a common identifiable cause of low back pain in young athletes, reportedly has a higher incidence rate in males. However, the reason for its higher incidence in males is not clear. This study aimed to investigate the epidemiological differences between the sexes in adolescent patients with lumbar spondylolysis., Methods: A retrospective study was conducted in 197 males and 64 females diagnosed with lumbar spondylolysis. These patients visited our institution from April 2014 to March 2020 with their main complaint being low back pain, and they were followed-up until the end of their treatment. We investigated associations between lumbar spondylosis, their background factors, and characteristics of the lesions and analyzed their treatment results., Results: Males had a higher prevalence of spina bifida occulta (SBO) (p = 0.0026), more lesions with bone marrow edema (p = 0.0097), and more lesions in the L5 vertebrae (p = 0.021) than females. The popular sports disciplines were baseball, soccer, and track and field in males, and volleyball, basketball, softball in females. The dropout rate, age at diagnosis, bone union rate, and treatment period did not differ between the sexes., Conclusion: Lumbar spondylolysis was more common in males than in females. SBO, bone marrow edema, and L5 lesions were more frequent in males, and sports discipline varied between the sexes., (© 2023. The Author(s).)

Introduction: This study aimed to determine whether the proximity of the median arcuate ligament (MAL) and the celiac artery (CA) changes in patients following surgery to correct adult spinal deformity (ASD). We hypothesized that the distance between the MAL and the CA shortens after corrective spinal surgery, which may cause acute celiac artery compression syndrome (ACACS)., Methods: A total of 89 patients (68.4±7.6 years; 7 men/82 women) with ASD treated with spinal correction surgery were included in the present retrospective study. The level of the MAL, CA, and distance between the MAL and the CA (DMC) were determined via reconstructed computed tomography. MAL overlap was determined preoperatively and postoperatively., Results: The MAL and CA moved caudally following surgery. On average, after surgery, no changes in DMC were observed. We found preoperative MAL overlap in 32 (36%) patients, who also had postoperative MAL overlap. No patients showed any MAL overlap postoperatively., Conclusions: Contrary to our hypothesis, the distance between the MAL and the CA did not shorten, and emerging MAL overlap was not observed postoperatively., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2023 The Japanese Society for Spine Surgery and Related Research.)

Introduction: Lumbar spondylolysis is a common fatigue fracture of the pars interarticularis of the lamina of the lumbar spine in adolescent athletes presenting with pars clefts. Some pseudarthrotic lumbar spondylolysis causes low back pain or radiculopathy. This study presents a case of pseudarthrotic lumbar spondylolysis that was successfully treated using a modified smiley face rod technique., Technical Note: We developed a modified smiley face rod technique, which places pedicle screws in the lateral edge of the pedicle to preserve the erector spinae muscles and inserts a U-shaped rod between the spinous processes to preserve the supraspinous ligament. When a U-shaped rod penetrates the interspinous ligament subcutaneously, the resection of the supraspinous ligaments can be avoided. When the screw head is positioned more anterolaterally, a compression force is applied perpendicular to the surface of the pars cleft by rod clamping. This intrasegmental fusion technique preserves the mobile segment and simultaneously repairs the pars cleft. It is less invasive and more appropriate than interbody fusion for young athletes to avoid the possibility of future adjacent segment disorders., Conclusions: This is a minimally invasive procedure that can easily achieve bone fusion and should be introduced for patients who are suffering from the symptoms of pseudarthrotic lumbar spondylolysis., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2023 The Japanese Society for Spine Surgery and Related Research.)

Background: Factors affecting bone union in the conservative treatment of adolescent lumbar spondylolysis remain controversial. We aimed to examine these factors along with advances in diagnostic imaging using multivariable analysis of a sufficient number of patients and lesions., Methods: In this retrospective study, high-school-aged patients or younger (n = 514) who were diagnosed with lumbar spondylolysis from 2014 to 2021 were investigated. We included patients with acute fractures who showed signal changes around the pedicle on magnetic resonance imaging and who completed conservative treatment. The following factors were investigated at the initial visit: age, sex, level of lesion, main side stage, presence and stage of contralateral side lesion, and presence of spina bifida occulta. The association of each factor with bone union was evaluated through a multivariable analysis., Results: Altogether, 298 lesions in 217 patients (174 boys and 43 girls; mean age: 14.3 years) were included in this study. Multivariable logistic regression analysis of all factors showed that the main side progressive stage was more likely associated with nonunion as compared to the pre-lysis (OR: 5.86; 95% confidence interval [CI]: 2.00-18.8; p = 0.0011) and early stages (OR: 3.77; 95% CI: 1.72-8.46; p = 0.0009). Regarding the contralateral side stage, the terminal stage was more likely to be associated with nonunion., Conclusion: In the conservative treatment of lumbar spondylolysis, the factors affecting bone union were the main and contralateral side stages. Sex, age, level of lesion, or spina bifida occulta had no significant effects on bone union. The main, progressive, and contralateral side terminal stages were negative predictors of bone union. Trial registration This study was retrospectively registered., (© 2023. The Author(s).)

Study Design: Retrospective cohort study., Purpose: To evaluate the clinical outcomes of the conservative treatment of "pre-lysis"-stage lumbar spondylolysis., Overview of Literature: With the widespread use of magnetic resonance imaging (MRI) for early diagnosis of lumbar spondylolysis, a new disease stage called pre-lysis has emerged, in which intensity change is observed only on MRI without a fracture line on computed tomography. This study aimed to evaluate the clinical outcomes and factors unfavorable to bone healing of the conservative treatment of pre-lysis-stage lumbar spondylolysis., Methods: Fifty-three patients with 57 fresh pre-lysis-stage lesions who had completed conservative treatment were included in the study (40 men, 13 women; mean age, 14.3 years). We investigated the rate of bone healing and the relationship between bone healing after conservative therapy and factors such as age, sex, vertebral level, unilateral/bilateral lesions, and presence of spina bifida occulta., Results: The overall bone healing rate was 95% (54/57 lesions). Bilateral lesions had a significantly lower bone healing rate than unilateral lesions (86% vs. 100%, p=0.046). There were no statistically significant differences based on age, sex, vertebral level, or presence of spina bifida occulta., Conclusions: The bone healing rate in unilateral lesions was 100%, which was significantly higher than that in bilateral lesions. It is important to detect and initiate treatment while the lesion is still unilateral, if possible.

Introduction: The effect of spina bifida occulta (SBO) on bone union in lumbar spondylolysis is controversial. The study aim was to assess the effect of SBO on bone union after conservative treatment of L5 spondylolysis, the most common level., Methods: The study included 191 lesions in 145 patients (mean age, 14.0 years) with conservatively treated L5 spondylolysis. We examined the relationships between bone union after conservative treatment and the number of SBOs, levels, and single or multilevel status. Fisher's exact probability test, chi-square test, and Welch's T test were performed., Results: The SBO incidence was 53%, with at least one SBO at any vertebral level. SBO at S1 ( p =0.034) or S2 ( p =0.0003), two SBOs ( p =0.0018), and three SBOs ( p =0.011) were associated with a lower bone union rate. The bone union rate was significantly lower for lesions with SBOs at both S1 and S2 than without (42% vs. 79%; p <0.0001)., Conclusions: The SBO incidence in L5 spondylolysis was 53%. SBO at S1 or S2 and a higher number of SBOs were associated with lower bone union rates. In particular, the bone union rate of lesions with SBOs at both S1 and S2 was <50%., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2023 The Japanese Society for Spine Surgery and Related Research.)

Purpose: Spinal fusion reduces flexibility, but we do not have detailed knowledge that accounts for growth or sex differences. We sought to determine trunk flexibility pre- and postoperatively in patients with adolescent idiopathic scoliosis (AIS)., Methods: We included data from 109 patients with AIS in this retrospective, single-center observational study. Patients had performed a sit-and-reach (SR) test preoperatively, and 1 and 2 years postoperatively, and measurements were standardized to Z scores according to age and sex. The patient data were divided into three groups according to the level of lower instrumented vertebra (LIV): (1) Group A (fusion above L2); (2) Group B (fusion to L2), and (3) Group C (fusion to L3 or L4). The change in the Z score for various levels was determined and compared., Results: The preoperative Z score for all patients was -0.622. At 2 years postoperatively, the Z score in Groups A and B was not significantly different from the preoperative score; in Group C, the Z score decreased by 1 year postoperatively, improved during the second year, but remained significantly lower than the preoperative score. Our study was the first to assess trunk flexibility using the SR test in patients with scoliosis., Conclusions: Preoperatively, patients with AIS had lower SR test Z-scores than the general population, indicating a lower trunk flexibility in these patients. At 2 years after surgery in these patients, trunk flexibility had returned to preoperative levels when LIV was at L2 or above, but when LIV was at L3 or L4, trunk flexibility was less than it was preoperatively., Level of Evidence: Prognostic Level II: retrospective study., (© 2022. The Author(s), under exclusive licence to Scoliosis Research Society.)

Although the incidence of cervical spinal cord injury (CSCI) with ossification of the posterior longitudinal ligament (OPLL) has increased in older adults, its etiology and neurological outcomes remain unknown. We identified OPLL characteristics and determined whether they influence neurological severity and improvement of CSCI in older patients. This multicenter retrospective cohort study identified 1512 patients aged ≥ 65 years diagnosed with CSCI on admission during 2010-2020. We analyzed CSCI etiology in OPLL patients. We performed propensity score-adjusted analyses to compare neurological outcomes between patients with and without OPLL. Cases were matched based on variables influencing neurological prognosis. The primary neurological outcome was rated according to the American Spine Injury Association (ASIA) impairment scale (AIS) and ASIA motor score (AMS). In 332 OPLL patients, the male-to-female ratio was approximately 4:1. Half of all patients displayed low-energy trauma-induced injury and one-third had CSCI without a bony injury. Propensity score matching created 279 pairs. There was no significant difference in the AIS grade and AMS between patients with and without OPLL during hospitalization, 6 months, and 12 months following injury. OPLL patients tended to exhibit worse neurological findings during injury; nevertheless, OPLL was not associated with poor neurological improvement in older CSCI patients., (© 2023. The Author(s).)

Introduction: This study aims to investigate risk factors for cage subsidence following minimally invasive lateral corpectomy for osteoporotic vertebral fractures., Methods: Eight males and 13 females (77.2±6.0 years old) with osteoporotic vertebral fractures who underwent single corpectomy using a wide-footprint expandable cage with at least a 1-year follow-up were retrospectively included. The endplate cage (EC) angle was defined as the angle between the vertebral body's endplate and the cage's base on the cranial and caudal sides. A sagittal computed tomography scan was performed immediately after surgery and at the final follow-up, with cage subsidence defined as subsidence of ≥2 mm on the cranial or caudal side. Risk factors were analyzed by dividing cases into groups with ( n =6) and without ( n =15) cage subsidence., Results: No significant differences were noted in age, bone mineral density, number of fixed vertebrae, sagittal parameters, preoperative and final kyphosis angle, amount of kyphosis angle correction, bone union, screw loosening, and number of other vertebral fractures preoperatively and 1-year postoperatively between the two groups. No difference was noted in cranial EC angle, but a significant difference was noted in caudal EC angle in the group with (10.7±4.1°) and without (4.7±4.2°) subsidence ( P =0.008). Logistic regression analysis with the dependent variable as presence or absence of subsidence showed that caudal EC angle (>7.5°) was a significant factor (odds ratio: 20, 95% confidence interval: 1.655-241.7, P =0.018)., Conclusions: In minimally invasive lateral corpectomy for osteoporotic vertebral fractures, a cage tilted more than 7.5° to the caudal vertebral endplate is a risk factor for cage subsidence. The cage should be placed as perpendicular to the endplate as possible, especially to the caudal vertebral body, to avoid cage subsidence., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2023 The Japanese Society for Spine Surgery and Related Research.)

The usefulness of minimally invasive posterior fixation without debridement and autogenous bone grafting remains unknown. This multicenter case series aimed to determine the clinical outcomes and limitations of this method for thoracolumbar pyogenic spondylitis. Patients with thoracolumbar pyogenic spondylitis treated with minimally invasive posterior fixation alone were retrospectively evaluated at nine affiliated hospitals since April 2016. The study included 31 patients (23 men and 8 women; mean age, 73.3 years). The clinical course of the patients and requirement of additional anterior surgery constituted the study outcomes. The postoperative numerical rating scale score for lower back pain was significantly smaller than the preoperative score (5.8 vs. 3.6, p = 0.0055). The preoperative local kyphosis angle was 6.7°, which was corrected to 0.1° after surgery and 3.7° at the final follow-up visit. Owing to failed infection control, three patients (9.6%) required additional anterior debridement and autogenous bone grafting. Thus, in this multicenter case series, a large proportion of patients with thoracolumbar pyogenic spondylitis could be treated with minimally invasive posterior fixation alone, thereby indicating it as a treatment option for pyogenic spondylitis.

Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest.

Update: This article was updated on October 19, 2022, because of previous errors, which were discovered after the preliminary version of the article was posted online. On page 1787, in the legend for Figure 2, the sentence that had read "The vertebral collapse rate (in %) was defined as 1 - (A/P) × 100, and vertebral instability (in %) was defined as the difference in vertebral collapse rate between the loaded and non-loaded images." now reads "The vertebral collapse rate (in %) was defined as (1 - [A/P]) × 100, and vertebral instability (in %) was defined as the difference in vertebral collapse rate between the loaded and non-loaded images." On page 1788, in the section entitled "Data Collection," the sentence that had read "The vertebral collapse rate (in %) was defined as 1 - (anterior vertebral wall height/posterior vertebral wall height) × 100, and vertebral instability (in %) was defined as the difference in vertebral collapse rate between the loaded and non-loaded images 9 ." now reads "The vertebral collapse rate (in %) was defined as (1 - [anterior vertebral wall height/posterior vertebral wall height]) × 100, and vertebral instability (in %) was defined as the difference in vertebral collapse rate between the loaded and non-loaded images 9 ." Finally, on page 1791, in Table IV, the footnote for the "Primary outcome" row that had read "N = 113 in the rest group and 99 in the no-rest group." now reads "N = 116 in the rest group and 108 in the no-rest group.", Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/H215 )., (Copyright © 2022 by The Journal of Bone and Joint Surgery, Incorporated.)

Introduction: Lumbar spondylolysis typically arises during adolescence, whereas its onset in adulthood is rare. Several studies have reported incidentally identified terminal-stage spondylolysis in adults, but only one case series has investigated acute lumbar spondylolysis lesions with bone marrow edema in adults., Methods: We retrospectively investigated lumbar spondylolysis in patients aged 18 years or older. Age at diagnosis, sex, competitive sporting level, and competitive sporting discipline were investigated in each patient. The level of the affected vertebra, pathological stage, bone union, and treatment period were analyzed for each lesion., Results: The study included nine patients (eight males and one female), aged 18-22 years old, with 14 acute lumbar spondylolysis lesions. Four patients were soccer players (two professionals, and two amateurs), four were amateur track and field athletes, and one was an amateur basketball player. The affected vertebral levels were L3 in two lesions, L4 in seven lesions, and L5 in five lesions. The pathological stage was pre-lysis stage in two lesions, early stage in eight lesions, and progressive stage in four lesions. Ten lesions achieved bone union with conservative therapy. The average treatment period was 84.7 days., Conclusions: The adult-onset lumbar spondylolysis patients were young, up to their early 20s, and generally professional sportspeople performing at an elite level. Most of them were performing a sport that has been reported to have a high risk of causing lumbar spondylolysis. L4 was the most affected vertebral level in contrast to L5, which has been reported in adolescent lumbar spondylolysis. Bone union was achieved for most lesions with conservative therapy., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2023 The Japanese Society for Spine Surgery and Related Research.)

Introduction: Magnetic resonance imaging (MRI) is widely used in orthopedics, but orthopedic surgeons, including spine surgeons, do not have detailed knowledge of MRI-related accidents. We, as orthopedic surgeons, investigated the details of medical accidents related to ferromagnetic objects brought into the MRI room using a national multicenter database., Methods: We conducted an exploratory analysis of accidents involving MRI ferromagnets based on the Japanese database of adverse medical occurrences. From a total of 104,659 accident reports over nine years, 172 involving the presence of ferromagnetic objects in the MRI room were extracted and analyzed., Results: The accident reports frequently involved children and the elderly. Nurses filed the highest number of reports (44.8%) by occupation, which was more than twice as many as physicians (19.8%). The most common ferromagnetic devices brought into the MRI rooms were pacemakers (n = 22). There were also large magnetic objects such as oxygen cylinders (n = 12) and IV stands (n = 7). In the field of orthopedics, ankle weights (n = 4), pedometers (n = 3), and artificial limbs (n = 2) were brought in. "Failure to check" was the most common cause of accidents (69%). Actual harm to patients occurred in 9% of cases, with no fatalities., Conclusions: Manuals and checklists should be developed and continuous education provided to prevent accidents involving magnetic objects brought into the MR scanner room. As orthopedic surgeons, including spine surgeons, we should be cautious with emergency, geriatric, and pediatric patients because their information and medical history may not be accurate. We should not overlook equipment commonly found in orthopedic practice such as ankle weights and pedometers., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2023 The Japanese Society for Spine Surgery and Related Research.)

Rectangular endcap expandable cages are common in anterior thoracolumbar spine restoration. However, the cage is often too large to place in small, elderly women. In this study, we evaluated a method to place a round endcap expandable cage on the vertebral ring apophysis in elderly women. From April 2017 to August 2020, five women (mean age 75.8 years) underwent anterior-posterior spinal fusion with a round endcap expandable cage on the vertebral ring apophysis at the thoracolumbar junction. The local kyphotic angle, coronal Cobb angle, and intervertebral height were evaluated pre-and postoperatively. Cage subsidence and bone union were evaluated. The mean local kyphotic angle, coronal Cobb angle, and intervertebral height before surgery were 35.2°, 10.0°, and 65.3 mm, respectively. Immediately postoperatively, 1 week and 3 weeks after surgery, the kyphotic angle was 13.4°, 16.6°, and 18.5°; coronal Cobb angle was 2.8°, 2.2°, and 4.3°; and intervertebral height was 76.2 mm, 71.8 mm, and 70.6 mm. Cage subsidence was not observed and the bone union was achieved in all cases. An expandable cage with a round endcap was placed in small, elderly women by inserting the cage over the strong apophysis of the vertebral body. This technique may be useful to reduce the risk of postoperative subsidence and correction loss., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Okuwaki et al.)

Occasionally lumbar spondylolysis in adolescents will recur after conservative treatment. The goal of this study was to retrospectively review the conditions in which recurrence transpired in a subset of adolescent patients diagnosed with acute lumbar spondylolysis. A retrospective survey was conducted in 141 patients who had been treated for spondylolysis and had obtained bone union. Twenty subjects were selected who had recurrent lumbar spondylolysis after returning to sports activity following the initial spondylolysis treatment. There were 18 males and two females with an average age at the time of initial visit of 13.3 years and 14.1 years at the time of recurrence. The average period of initial treatment was 101 days, and the average time to recurrence after healing was 149 days. There were three cases at L3, two cases at L4 and 15 cases at L5. At recurrence, 18 patients had unilateral involvement and two patients presented with bilateral occurrence. Four cases did not achieve bony union. In this study, the recurrence rate was 13.2%. Eighty percent of cases had recurrence within six months after healing. After recurrence, 20% of the cases reached pseudoarthrosis. It is useful to take regular MRI images to detect recurrence within six months after returning to sports., (© 2022. The Author(s).)

Background: This study evaluated the union rate of acute lumbar spondylolysis in patients treated conservatively, according to the protocol., Methods: The subjects included high school students and younger patients who were diagnosed with lumbar spondylolysis presenting bone marrow edema. We investigated the union rate, the period until union, unilateral or bilateral, vertebral level, laterality (right or left), and pathological stage at the first visit. Some unilateral cases included bilateral spondylolysis with contralateral pseudarthrotic lesion; therefore, the union rate of the "true" unilateral case in which the contralateral side was normal was calculated. We excluded multi-level lesions., Results: With conservative treatment for lumbar spondylolysis of 189 lesions in 142 cases, 144 healed and 45 were considered as nonunion. The average treatment period until union was 106 days. The union of "true" unilateral cases in which the contralateral side was normal was noted in 68/71 lesions, but that of bilateral cases was noted in 71/94 lesions. The union in L3, L4, and L5 vertebrae was noted in 15/17, 40/49, and 89/123 lesions, respectively. The union was observed in 63/87 on the right and 86/102 on the left. The union was noted in the pre-lysis, early, and progressive stages in 36/39, 81/97, and 27/53 lesions, respectively. Furthermore, the union was noted in stages 0, 1a, 1b, 1c, and 2 in 13/15, 47/52, 30/36, 34/42, and 20/44 lesions, respectively., Conclusion: Accurate union evaluation using CT and MRI showed a union rate of 76% with conservative treatment for spondylolysis. The union rate of the "true" unilateral cases in which the contralateral side was normal was 96%, which was significantly higher than that of the bilateral cases. Moreover, the union rate of lesions in the axial progressive stage and sagittal stage 2 was significantly lower than that of lesions in other stages., Study Design: clinical retrospective study., Competing Interests: Declaration of competing interest The authors declare that there are no relevant conflicts of interest., (Copyright © 2021 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Introduction: We aimed to investigate the risk factors that affect vertebral deformity 6 months after osteoporotic vertebral fractures (OVFs) at the time of injury., Materials and Methods: From May 2017 to May 2020, 70 postmenopausal women with OVFs were evaluated for age; body mass index; number of previous OVFs; total 25-hydroxy vitamin D [25(OH)D] levels; posterior wall injury on computed tomography; cross-sectional area (CSA) of the psoas major, erector spinae, and multifidus; fat infiltration; vertebral instability (VI) upon admission; collapse rate (CR); and kyphotic angle (KA) at 6 months after injury. A multiple regression analysis was conducted to identify the risk factors for the CR and KA., Results: The CR was correlated with posterior wall injury (r = 0.295, p = 0.022), 25(OH)D levels (r =  - 0.367, p = 0.002), and VI (r = 0.307, p = 0.010). In the multiple regression analysis, the 25(OH)D levels (p = 0.032) and VI (p = 0.035) were significant risk factors for the CR at the 6-month follow-up. The KA was correlated with the 25(OH)D levels (r =  - 0.262, p = 0.031) and VI (r = 0.298, p = 0.012). In the multiple regression analysis, the CSA of the psoas major (p = 0.011) and VI (p < 0.001) were significant risk factors for the KA at the 6-month follow-up., Conclusion: In cases with large VI at the time of injury, the CR and KA were significantly higher at 6 months after injury. Moreover, the CR was affected by the 25(OH)D level, while the KA was affected by the CSA of the psoas major upon admission., (© 2021. The Japanese Society Bone and Mineral Research.)

Objectives The objective of this study was to verify the usefulness of magnetic resonance imaging (MRI) with axial traction of the thumb for observing articular cartilage. Materials and methods Eleven healthy adult volunteers (39.7 ± 7.4 years) without thumb carpometacarpal joint arthritis or trauma were included in this study. A 3-tesla (3T) MRI (Magnetom Skyra, Siemens Healthineers AG, Munich, Germany) of the right thumb with axial traction applied by a finger trap with three traction weights (0, 2, and 5 kg) was performed. A 3D T2* multiecho data imaging combination (MEDIC) was selected to visualize the articular cartilage. After multiplanar reconstruction, sagittal and coronal images of the thumb carpometacarpal joint were used to evaluate the articular cartilage visibility and joint space widths at five locations. Articular cartilage visibility was evaluated using our original classification method that used the percentage of the cartilage detectable area. The Friedman test was used to compare the differences between each traction weight and location. Results Articular cartilage visibility significantly improved with axial traction. The average joint space widths with the 5-kg application were 1.9 ± 0.8, 3.9 ± 0.6, 2.0 ± 0.9, 3.9 ± 1.1, and 2.5 ± 1.4 mm at the center, volar edge, dorsal edge, radial edge, and ulnar edge, respectively. The joint space widths significantly increased proportionally with the traction weight at all locations. The joint space widths at the volar and radial edges were significantly greater than those at other locations. Conclusion Applying axial traction to the thumb increased the joint space widths and improved the visibility of the articular cartilage in the carpometacarpal joint on MRI., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Ikumi et al.)