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Retrospective case series.The purpose of this study was to investigate the outcome of multilevel posterior decompression surgery for degenerative lumbar spinal stenosis compared with single-level surgery.The clinical outcomes of multilevel decompression surgery are still controversial because previous studies have not been designed to randomize or adjust the patient background.A retrospective review of prospectively collected data from 659 surgically treated lumbar spinal stenosis patients with a minimum 2-year follow-up was performed. Among them, we compared baseline and 2-year postoperative patient-reported outcomes (PROs) including the Visual Analog Scale and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire scores of 122 patients who underwent three or more levels of surgery (M group) and 304 patients who underwent single-level surgery (S group). Further analyses were performed of 116 paired patients from both groups who were propensity score matched by age and baseline PROs.The number of perioperative complications including extradural hematoma, surgical site infection, and spinal fluid leakage [M vs. S: 10 (8%) vs. 19 (6%), P =0.47], and frequency of revision surgery [5 (4%) vs. 23 (8%), P =0.10] were similar between the two groups. In the analysis of propensity score-matched patients, there were comparable improvements in the Visual Analog Scale score for lower back pain (2.6 vs. 2.4, P =0.55), buttock-leg pain (3.1 vs. 3.4, P =0.48), and buttock-leg numbness (2.9 vs. 2.9, P =0.77) in both groups. There were also similar improvements in the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire scores including lower back pain, lumbar function, walking ability, and mental health domains, except for the social life function domain (20.7±26.5 vs. 28.0±27.5, P =0.04).Despite the longer surgical time and a larger volume of estimated blood loss, multilevel decompression surgery showed similar improvement to that of single-level surgery in terms of recovery of PROs and frequency of revision surgery. Multilevel decompression surgery provides good clinical outcomes with acceptable complication and revision rates when selecting appropriate patient and spinal levels.

A prospective multicenter study.This study aims to evaluate patient-reported outcomes using the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) and clarify clinical factors that affect the therapeutic effects for patients with cervical ossification of the posterior longitudinal ligament (OPLL).Although previous studies identified factors that affected the surgical outcomes, their assessment was mainly based on the Japanese Orthopedic Association score, which only includes neurological function. Investigating this pathology through multiple functions and quality of life (QOL) is pivotal to understanding the comprehensive clinical pictures of the cervical OPLL and its therapeutic outcomes.This study was performed by the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. A total of 478 patients with myelopathy caused by cervical OPLL from 28 institutions were prospectively registered from 2014 to 2017 and followed up for 2 years. Of the patients, 168 received laminoplasties and fully completed questionnaires. Demographic information, imaging findings, and clinical outcomes were collected. Patients were grouped according to effective or ineffective surgical outcomes as defined by the JOACMEQ using logistic regression analyses.Laminoplasty resulted in functional improvement in the cervical spine and upper extremity around 40% of the patients, while QOL showed only 21.4% ( P0.01). Multivariable analyses revealed that younger age and a postoperative decrease in arm or hand pain were correlated with significantly improved function of the upper extremities. A reduction in lower limb pain favorably affected the postoperative lower extremity function. A postoperative reduction in upper extremity pain enhanced the QOL recovery.Surgeons should recognize the diversity of surgical outcomes after laminoplasty and understand the necessity of pain management even after the surgery to enhance bodily functions and QOL in patients with cervical OPLL.

MINI A retrospective multicenter study with propensity scoring revealed the impact of the intervertebral level of stenosis on surgical outcomes of posterior decompression for cervical spondylotic myelopathy. Functional recovery was not different between the upper and lower cervical stenosis groups. Posterior decompression is effective, regardless of the intervertebral level of stenosis. STUDY DESIGN Retrospective multicenter study. OBJECTIVE To identify the impact of the intervertebral level of stenosis on surgical outcomes of posterior decompression for cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA As the upper affected cervical levels in elderly patients result from degenerative changes in the lower cervical levels with aging, it is usually difficult to determine the influence of the upper affected cervical levels on surgical outcomes after posterior decompression for CSM in older age. METHODS This study involved 636 patients with CSM who underwent posterior decompression. According to the most stenotic intervertebral level, patients were divided into upper (n = 343, the most stenotic intervertebral level was C2/3, C3/4, or C4/5) and lower (n = 293, the most stenotic intervertebral level was C5/6, C6/7, or C7/T1) cervical stenosis groups. Propensity score matching of the baseline factors (characteristics, comorbidities, and neurological function) was performed to compare surgical outcomes, the Japanese Orthopaedic Association (JOA) scores, and visual analog scale (VAS) for neck pain between the upper (n = 135) and lower (n = 135) cervical stenosis groups. RESULTS Before propensity score matching, age at surgery was older and pre- and postoperative JOA scores were lower in the upper cervical stenosis group (P

Study design A retrospective study of consecutive collected data. Objective To investigate risk factors for postoperative distal adding-on (DA) in Lenke Type 1B and 1C curves using intraoperative radiographs. Summary of background data In adolescent idiopathic scoliosis (AIS), DA radiographic complication can negatively affect postoperative clinical results. However, few studies have focused on assessing risk factors for DA using intraoperative radiographs. Methods We retrospectively evaluated 69 AIS patients with Lenke Type 1B or 1C curves who underwent posterior selective thoracic fusion. We divided patients into DA and non-DA groups based on radiograph data at 2-year follow-up using Wang et al. (Spine 2011) definition of DA. We compared coronal radiographic parameters, including relative positions of end vertebra (EV), stable vertebra (SV), neutral vertebra (NV), and last touching vertebra (LTV) to lowest instrumented vertebra (LIV), and intraoperative radiographic parameters, between the two groups. Results DA was present in 13 patients (18.8%) at 2-year follow-up. The mean LIV-EV, LIV-NV, LIV-SV, and LIV-LTV relative positions were significantly smaller in the DA group than in the non-DA group. Multivariate analysis showed that LIV-LTV was significantly associated with DA (DA:-0.2 ± 0.7, non-DA: 0.6 ± 0.7). Intraoperative radiographs showed that the mean angulation of the first disc below the LIV after final adjustment was significantly larger in the DA group (2.3° ± 1.1°) than in the non-DA group (0.9° ± 0.7°). Patients whose angulation of the first disc below the LIV was more than 3° were significantly associated with DA. Conclusion The LIV selected at more cranial to the LTV may be a risk factor for postoperative DA in Lenke Type 1B and 1C curves. Moreover, it was suggested that LIV extension might be considered when the first disc's angulation below the LIV is > 3° in intraoperative radiographs.Level of Evidence: 3.

Study design A retrospective analysis of prospectively collected data. Objective This study aimed to create a prognostic model for surgical outcomes in patients with cervical ossification of the posterior longitudinal ligament (OPLL) using machine learning (ML). Summary of background data Determining surgical outcomes helps surgeons provide prognostic information to patients and manage their expectations. ML is a mathematical model that finds patterns from a large sample of data and makes predictions outperforming traditional statistical methods. Methods Out of 478 patients, 397 and 370 patients had complete follow-up information at 1 and 2 year respectively and were included in the analysis. A minimal clinically important difference (MCID) was defined as an acquired Japanese Orthopaedic Association (JOA) score of 2.5 points or more, after which a ML model that predicts whether MCID can be achieved 1 and 2 years after surgery was created. Patient background, clinical symptoms, and imaging findings were used as variables for analysis. The ML model was created using LightGBM, XGBoost, random forest, and logistic regression, after which the accuracy and area under the receiver operating characteristic curve (AUC) were calculated. Results The mean JOA score was 10.3 preoperatively, 13.4 at 1 year after surgery, and 13.5 at 2 years after surgery. XGBoost showed the highest AUC (0.72) and high accuracy (67.8) for predicting MCID at 1 year, while random forest had the highest AUC (0.75) and accuracy (69.6) for predicting MCID at 2 years. Among the included features, total preoperative JOA score, duration of symptoms, body weight, sensory function of the lower extremity sub-score of the JOA, and age were identified as having the most significance in most of ML models. Conclusion Constructing a prognostic ML model for surgical outcomes in patients with OPLL is feasible, suggesting the potential application of ML for predictive models of spinal surgery.Level of Evidence: 4.

STUDY DESIGN A prospective multicenter study. OBJECTIVE To evaluate and compare the surgical outcomes after open-door (OD) and double-door (DD) laminoplasties in subjects with cervical ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA Although previous studies compared clinical results after OD and DD laminoplasties, they were performed at a single institution with a relatively small sample size targeting mixed pathologies, including cervical spondylotic myelopathy. METHODS This study was performed by the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. A total of 478 patients with myelopathy caused by cervical OPLL from 28 institutions were prospectively registered from 2014 to 2017 and followed up for 2 years. Of these, 41 and 164 patients received OD and DD laminoplasties, respectively. Demographic information, medical history, and imaging findings were collected. Clinical outcomes were assessed using the cervical Japanese Orthopaedic Association, Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire, and visual analog scale scores. RESULTS Age, sex, symptom duration, and comorbidities were not significantly different between the groups. Segmental ossification was the most frequent in both the groups. No significant differences in K-line type, canal occupying ratio, C2 to C7 angles, and range of motion were found. Both the procedures reduced the cervical range of motion postoperatively. A comparable frequency of perioperative complications was observed between the groups. The cervical Japanese Orthopaedic Association scores showed a similar improvement at 2 years postopera- tively. The reduction in visual analog scale score for neck pain was favorable in the OD group (P = 0.02), while other pain assessments did not show any significant differences between the groups. The functional outcomes assessed using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire presented equivalent effective rates. CONCLUSION The results demonstrated almost comparable surgical outcomes between OD and DD laminoplasties. Lamino- plasty is a valuable technique as a therapeutic option for cervical OPLL.Level of Evidence: 2.

Bacterial survival on titanium alloy and cobalt–chromium alloy using in vitro and in vivo experiments was evaluated. Cobalt–chromium alloy suppressed Staphylococcus aureus and Propionibacterium acnes proliferation compared with titanium alloy in vitro and in an in vivo infection model., Study Design. In vitro and in vivo laboratory studies. Objective. This study aimed to compare bacterial survival on titanium alloy (Ti) and cobalt–chromium alloy (CC) using in vitro and in vivo experiments. Summary of Background Data. Spinal implants are frequently manufactured from Ti and CC. These foreign materials are thought to be susceptible to biofilm formation that contributes to the development of surgical site infections. Certain metals (i.e., silver, cobalt) are known to have antibacterial properties. Methods. In the in vitro study, discs made of Ti or CC were incubated with one of two common bacteria: Staphylococcus aureus (S. aureus) and Propionibacterium acnes (P. acnes). After incubation, discs were assessed to determine the number of viable bacterial cells. In the in vivo study, the discs that were made of CC or Ti were implanted into the subcutaneous layer of BALB/c mice. After skin closure, a suspension including either S. aureus or P. acnes was directly inoculated on the implanted discs. The discs were retrieved and analyzed to determine the number of viable bacteria at 0.5, 1, and 3 days after inoculation. Results. The number of viable S. aureus cultured from the CC discs was 0.9 ± 0.2 × 103 CFU/disc, which was significantly lower than the cultured Ti discs (114.8 ± 18.3 × 103 CFU/disc). Moreover, a significantly lower mean number of P. acnes were cultured with CC (1.9 ± 1.2 × 103 CFU/disc) compared with the Ti (180.0 ± 72.1 × 103 CFU/disc). The in vivo infection model testing against S. aureus or P. acnes showed a significantly lower number of viable S. aureus or P. acnes on CC discs than Ti discs. The result was seen at all measured time points. Conclusion. CC suppressed S. aureus and P. acnes proliferation compared with Ti in vitro and in an in vivo infection model. Level of Evidence: N/A

STUDY DESIGN A retrospective multicenter study. OBJECTIVE To determine the surgical site infection (SSI) rate, associated risk factors, and causative pathogens in pediatric patients with spinal deformity. SUMMARY OF BACKGROUND DATA There have been no extensive investigations of the risk factors for SSI in Japan. METHODS Demographic data, radiographic findings, and the incidence of SSI were retrospectively analyzed in 1449 pediatric patients who underwent primary definitive fusion surgery for spinal deformity at any of 15 institutions from 2015 to 2017. SSI was defined according to the US Centers for Disease Control and Prevention guideline. RESULTS The incidence of all SSIs was 1.4% and that of deep SSIs was 0.76%. The most common pathogenic microbes were methicillin-resistant staphylococci (n = 5) followed by gram-negative rods (n = 4), methicillin-sensitive staphylococci (n = 1), and others (n = 10). In univariate analysis, younger age, male sex, a diagnosis of kyphosis, type of scoliosis, American Society of Anesthesiologists (ASA) class ≥3, mental retardation urinary incontinence, combined anterior-posterior fusion, greater magnitude of kyphosis, three-column osteotomy, use of blood transfusion, and number of antibiotic administration were associated with the likelihood of SSI (all P

STUDY DESIGN Retrospective review. OBJECTIVE This study sought to determine how baseline motor weakness (MW) affects elective spine surgery in patients with degenerative lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA Favorable clinical outcomes have been described for elective spine surgery in patients with LSS. However, the way preoperative MW affects the patient's health-related quality of life (HRQoL) after surgery is not well understood. METHODS A retrospective review of prospectively collected data from 305 surgically treated patients with LSS who had 2-year follow-up was performed (age 71 ± 9 yrs, male 62%). Demographic, radiographic, and clinical outcomes were analyzed at baseline and at 1-year, 2-year, and 3-year postoperation. The Japanese Orthopedic Association Back Pain Evaluation Questionnaire was used to assess the HRQoLs. The HRQoLs were compared between those with or without preop MW. Adjusted multivariate logistic regression analyses were performed to determine whether MW affected HRQoLs. RESULTS One hundred sixteen patients (38%) were categorized as MW+. The patient background including age, sex, presence of degenerative spondylolisthesis, type of surgery, and presence of neurological claudication were similar between the two groups. However, the 1-, 2-, and 3-year postoperative visual analogue scale of back pain, leg pain, leg numbness, the Japanese Orthopedic Association Back Pain Evaluation Questionnaire lumbar function, social life, mental health, and walking ability were all inferior in the MW+ group, whereas a similar percentage of patients achieved a minimum clinically important difference in all subdomains at 3 years. The adjusted multivariate logistic regression analyses showed that having ≥2 muscles with MW, and severity of MW (manual motor test grade) were independent risk factors for both difficulty climbing stairs and walking >15 minutes. (muscles with MW≥2; stair climbing: OR 6.4[2.3-17.4], walking: OR 3.2[1.4-7.3], severity of MW; stair climbing: OR 2.5[1.4-4.4], walking: OR 2.2[1.3-3.7]). CONCLUSION The patients with baseline MW had inferior HRQoL for up to 3 years compared with that of those without MW; however, the amount of improvement in HRQoL was comparable. Timely follow-up is important to find out the deterioration of motor function.Level of Evidence: 4.

Study design This is a multicenter retrospective review of 257 surgically treated consecutive ASD patients who had a minimum of five fused segments, completed a 2-year follow-up (53 ± 19 yrs, females: 236 [92%]). Objective This study aimed to validate the predictive probability of the GAP score in an Asian ASD patient cohort. Summary of background data The GAP score is a recently established risk stratification model for MF following ASD surgery. However, the predictive ability of the GAP score is not well studied. This study aimed to validate the predictive probability of the GAP score in an Asian ASD patient cohort. Methods Comparisons of the immediate postoperative GAP scores between MF the and MF-free groups were performed. We evaluated the discriminative ability of the GAP score based on the area under the receiver operating characteristic curve (AUROC). The Cuzick test was performed to determine whether there is a trend between the GAP score and the incidence of MF or revision surgery. Univariate logistic regression analyses were performed to explore the associations between the GAP score and the incidence of MF or revision surgery. Results No difference was observed in the GAP score between the MF and MF-free groups (MF vs. MF-free; GAP: 5.9 ± 3.3 vs. 5.2 ± 2.7, P = 0.07). The Cuzick analysis showed no trend between the GAP score and the risk for MF or revision surgery. Likewise, the MF rate was not correlated with the GAP score, as shown by the ROC curve (AUC of 0.56 [95% CI 0.48-0.63], P = 0.124). Univariate logistic regression confirmed no associations between the GAP score and the incidence of MF or revision surgery (MF; moderately disproportioned [MD]: OR: 0.6 [95% CI: 0.3-1.2], P = 0.17, severely disproportioned [SD]: OR: 1.2 [95% CI: 0.6-2.3], P = 0.69, revision surgery; MD: OR: 0.8 [95% CI: 0.2-2.8], P = 0.71, SD: OR: 1.2 [95% CI: 0.9-8.7], P = 0.08). Conclusion In this multicenter study, in an Asian ASD patient cohort, the GAP score was not associated with the incidence of MF or revision surgery. Additional studies on the predictive ability of the GAP score in different patient cohorts are warranted.Level of Evidence: 3.

STUDY DESIGN Retrospective case series. OBJECTIVE The aim of this study was to compare the utility and cost-effectiveness of multilevel lateral interbody fusion (LIF) combined with posterior spinal fusion (PSF) (L group) and conventional PSF (with transforaminal lumbar interbody fusion) (P group) in adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA The clinical and radiographic outcomes of multilevel LIF for ASD have been reported favorable; however, the cost benefit of LIF in conjunction with PSF is still controversial. METHODS Retrospective comparisons of 88 surgically treated ASD patients with minimum 2-year follow-up from a multicenter database (L group [n = 39] and P group [n = 49]) were performed. Demographic and radiographic data, health-related quality of life (HRQoL), and the direct hospitalization cost for the initial surgery and 2-year total hospitalization cost were analyzed. RESULTS Analyses of sagittal spinal alignment showed no significant difference between the two groups at baseline and 2 years post-operation. Surgical time was longer in the L group (L vs. P: 354 vs. 268 minutes, P

Study design Immunohistochemical and real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis. Objective The aim of this study was to analyze the expression of five susceptibility genes (RSPO2, HAO1, CCDC91, RHPH9, and STK38L) for human ossification of the posterior longitudinal ligaments (OPLL) identified in a genome-wide association study. Summary of background data Detailed expression and functional studies for the five susceptibility genes are needed to aid in clarification of the etiology and pathogenesis of OPLL. Methods Immunostaining, cell culture, and real-time RT-PCR were performed on ossified ligament samples collected during anterior cervical decompression for symptomatic OPLL (n = 39 patients) and on control non-OPLL samples (n = 8 patients). Immunohistochemical analysis in spinal hyperostotic mice (ttw/ttw) (n = 25) was also performed. The sample sections were stained for RSPO2, HAO1, CCDC91, RHPH9, STK38L, Runx2, Sox9, and CD90. The mRNA expression levels of the five susceptibility genes were also analyzed in cultured human OPLL and non-OPLL cells subjected to cyclic tensile strain. Results Immunoreactivity for RSPO2 and Sox9 was evident in proliferating chondrocytes in human OPLL tissues and ttw/ttw mice. Application of cyclic tensile strain to cultured human OPLL cells resulted in increases in mRNA levels for RSPO2, HAO1, and CCDC91. However, individual differences in expression in human OPLL-related samples were seen. HAO1-positive cells were detected only in 3- to 6-week-old ttw/ttw mice that did not simultaneously express RSPO2-positive samples. Conclusion Among the five susceptibility genes, RSPO2, HAO1, and CCDC91 might be contributory factors in progression of OPLL. RSPO2 may be involved in endochondral ossification, especially in mixed or continuous type OPLL, HAO1 may be an initiation factor for OPLL that is rarely seen in mature human OPLL samples, and CCDC91 may be associated with progression of ossification caused by mechanical stress. These findings provide important insights into the pathogenesis and therapeutic targets for OPLL. Level of evidence N/ A.

Study design A multicenter retrospective case series. Objective The purpose of this study was to compare the clinical outcomes of a surgical treatment for adult spinal deformity (ASD) in the United States (US) with those in Japan (JP) in a matched cohort. Summary of background data Surgical outcomes of thoracic-lumbar-sacral (TLS) spinal fusions in adult spinal deformity ASD patients who live in Asian countries are poorly understood. Methods A total of 300 surgically treated ASDs of age more than 50 years with the lowest instrumented vertebra at the pelvis and a minimum follow-up of 2 years (2y) were consecutively included. Patients were propensity-score matched for age, sex, levels fused, and 2y postop sagittal spinal alignment. Demographic, surgical, and radiographic parameters were compared between the US and JP groups. Results A total of 186 patients were matched by propensity score and were almost identical within these parameters: age (US vs. JP: 66 ± 8 vs. 65 ± 7 yr), sex (females: 90% vs. 89%), levels fused (10 ± 3 vs. 10 ± 2), 2y C7 sagittal vertical axis (C7SVA) (5 ± 5 vs. 5 ± 4 cm), 2y Pelvic incidence minus lumbar lordosis (9 ± 15° vs. 9 ± 15°), and 2y pelvic tilt (PT) (25 ± 10° vs. 24 ± 10°). Oswestry Disability Index (ODI) scores and Scoliosis Research Society patient questionnaire ((SRS-22) function and pain scores were similar at 2y between the US and JP groups (ODI: 27 ± 19% vs. 28 ± 14%, P = 0.72; SRS-22 function: 3.6 ± 0.9 vs. 3.6 ± 0.7, P = 0.54; SRS-22 pain: 3.6 ± 1.0 vs. 3.8 ± 0.8, P = 0.11). However, significantly lower satisfaction was observed in JP than in the US (SRS-22 satisfaction: 4.3 ± 0.9 vs. 4.0 ± 0.8, P Conclusion Surgical treatment for ASD was similarly effective in patients in the US and in JP. However, satisfaction scores were lower in JP compared with the US. Differences in lifestyle and cultural expectations may impact patient satisfaction following ASD surgery. Level of evidence 3.

Study design Case-control study. Objective To examine factors influencing cervical alignment after corrective surgery for adult patients with adolescent idiopathic scoliosis (AdIS) SUMMARY OF BACKGROUND DATA.: Corrective surgery for spinal deformity influences postoperative cervical spinal alignment, but changes in the cervical alignment in adults with AdIS are scarcely reported. Methods We retrospectively examined 85 patients with AdIS who underwent posterior corrective surgery for thoracic or lumbar major curve and were followed up for 2 years. Clinical characteristics, radiographic parameters, and health-related quality of life (HRQOL) were evaluated. Cervical deformity (CD) was defined as one of the following cases: (1) T1 tilt minus C2-C7 angle more than 20°, (2) C2-C7 SVA more than 40 mm, (3) and C2-C7 angle less than -10°. Patients were divided into those with and without CD based on the defined criteria; statistically relevant factors were analyzed. Results There were 19 patients in the postoperative CD group. The average age at the time of surgery was lower in the CD group (26.5 vs. 31.4). In the CD group, the average preoperative T1 tilt was smaller (1.1° vs. 12.5°), and the C2-C7 angle was kyphotic (-16.1° vs. 3.0°). The average kyphotic angle at thoracic spine (T5-T12) was lower in the CD group preoperatively (12.5° vs. 19.5°) and postoperatively (15.2° vs. 20.8°). HRQOL outcomes were comparable between the groups. Of the patients with preoperative CD, 51.5% (n = 17) maintained their deformity at the final follow-up, and baseline C2-C7 angle was lower than those who converted to non-CD following surgery (n = 16) (-17.0° vs. -10.3°). Conclusion More than half of the patients with baseline CD maintained their cervical malalignment postoperatively. Patients with postoperative CD presented cervical kyphotic and thoracic hypokyphotic alignments before surgery. Because CD has the potential to lead to cervical degeneration, careful follow-up observation is necessary for these young patients. Level of evidence 3.

STUDY DESIGN Prospectively collected, multicenter, nationwide study. OBJECTIVE The aim of this study was to investigate recent surgical methods and trends, outcomes, and perioperative complications in surgery for thoracic ossification of the ligamentum flavum (T-OLF). SUMMARY OF BACKGROUND DATA A prospective multicenter study of surgical complications and risk factors for T-OLF has not been performed, and previous multicenter retrospective studies have lacked details for these items. METHODS Surgical methods, pre- and postoperative thoracic myelopathy (Japanese Orthopedic Association [JOA] score), symptoms, and intraoperative neurophysiological monitoring were investigated prospectively in 223 cases. Differences in these factors between fusion and nonfusion procedures for T-OLF were examined. The minimum follow-up period was 2 years after surgery RESULTS.: The mean JOA score was 6.2 points preoperatively, and 7.9, 8.2, and 8.2 points at 6 months, 1, and 2 year postoperatively, giving mean recovery rates of 35.0%, 40.9%, and 41.4% respectively. Posterior decompression and fusion with instrumentation was performed in 109 cases (48.9%). There were 45 perioperative complications in 30 cases (13.5%), with aggravation of motor disturbance in the lower extremities being most common (4.0%, n = 9). Patients treated with fusion had a significantly higher BMI, rate of gait disturbance, ossification occupation rate of OLF at computed tomography, and intramedullary high intensity area at magnetic resonance imaging (P

This is an international multicenter retrospective review of 219 surgically treated consecutive adult spinal deformity (ASD) patients who had a minimum of five fused segments, completed a 2-year follow-up.The purpose of this study was to add the indices of preventive procedures to improve and to validate the predictive probability of the PRISM (patient demographics, radiographic index, and surgical invasiveness for mechanical failure) for mechanical failure (MF) following ASD surgery.The PRISM was developed from the data of 321 ASD patients, which stratified the risk of MF from six types of risk.Data from 136 Japanese ASD patients (age 49 ± 21 yr, 88% female) were used to develop PRISM2, and data from 83 US ASD patients (age 58 ± 12 yr, 86% female) were used for the external validation. We analyzed the associations between three preventive procedures (UIV+1 tethering [TH], teriparatide [TP], and multirod [MR]) and MF by multivariate logistic regression analysis (MRA). The values for the nearest integer of the β of the procedures were added to the six indices of the original PRISM to establish the PRISM2. The discriminative ability of the PRISM/ PRISM2 for MF was evaluated using the area under the receiver operating characteristic curve (AUC) and the precision-recall (PR) curve. The Cochran-Armitage test was used to analyze the trend between PRISM/PRISM2 scores and MF.MF developed in 25% (34 cases). The β values for the preventive procedures calculated by MRA were TH: -2.5, TP: -3.0, and MR: -2.1. The Cochran-Armitage test showed an excellent trend between MF and PRISM/2. The diagnostic ability was superior for the PRISM2 compared with the PRISM (PRISM2; AUC = 0.94 [0.90-0.98], PRISM; AUC = 0.87 [0.81-0.93], difference = -0.07 [-0.11 to -0.03], P 0.01). The AUC of the PRISM2 was 0.70 [0.59-0.81, P 0.01] in the US patient cohort.We refined the PRISM by adding preventive procedures to the risk indices. Further validation and adjustment in a large different patient cohorts may improve the predictive probability of PRISM2.Level of Evidence: 3.

Study design A prospective multicenter study. Objective This study aims to investigate the postoperative complications of anterior decompression with fusion (ADF) for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL). Summary of background data Surgical treatment for cervical OPLL has a high risk of various complications. ADF is reported to be effective for cervical OPLL, especially for massive OPLL. However, few studies have focused on the surgical complications of ADF. Methods We prospectively included 102 patients undergoing ADF for severe cervical OPLL with average canal occupying ratio of 49.8%. We evaluated systemic and local complications, neurological complications, and risk factors related to the postoperative complications. Results Frequently observed complications included graft/ implant complications (18.6%), neurological complications (11.8%), and cerebrospinal fluid leak (11.8%). Motor palsy involving only the upper extremity was found in nine patients (8.8%), and other motor palsies involving the lower extremities were found in three patients (2.9%). None of the preoperative factors were significantly associated with the occurrence of neurological palsies, whereas the number of operated levels was a significant factor related to the postoperative graft/implant complications (P = 0.003; odds ratio, 2.112). The incidence of graft/implant complications and related reoperation increased as the number of operated levels increased (especially four levels or more). Most motor palsies were observed immediately after surgery. Of the motor palsies in the bilateral upper extremities and palsies involving the lower extremities, 85.7% showed good recovery, whereas only 40% of unilateral upper extremity motor palsies showed good recovery during the follow-up period. Conclusion In ADF for cervical OPLL, the number of operated levels was a significant factor related to the postoperative complication. Specifically, the incidence of graft/implant complications and reoperation rate increased in ADF with four or more levels.Level of Evidence: 3.

STUDY DESIGN Multicenter retrospective case series of patients treated surgically for lumbar spinal stenosis (LSS). OBJECTIVE We investigated how laminectomy improves lower back pain (LBP) and the factors associated with poor improvement. SUMMARY OF BACKGROUND DATA Lumbar laminectomy is effective for alleviating neurological symptoms caused by LSS, whereas its effect on LBP is still controversial. METHODS A retrospective review of prospectively collected data from 436 patients (age 72 yrs, 69% males) who underwent laminectomy for LSS with 2 years of follow-up. We analyzed the following risk factors for residual LBP by uni- and multivariate analyses: age, sex, smoking, occupation, comorbidities, frailty, joint replacement, vertebral fracture, DISH, HRQOL, complications, and the presence of spinal instability. The LBP of male and female patients was analyzed after propensity score matching of known confounders. Patient-reported outcomes (JOABPEQ and VAS scores) were obtained at baseline and the 2-year postoperative follow-up. RESULTS LBP was significantly improved at 2 years post operation (VAS change 2.3 [95% CI 2.0-2.6], P

Study design Multicenter, retrospective cohort study. Objective The aim of this study was to investigate the occurrence and surgical predictors of postoperative shoulder imbalance (PSI) in Lenke type 2A adolescent idiopathic scoliosis (AIS). Summary of background data Although several studies have investigated the factors influencing PSI in Lenke type 2 curves, no studies have analyzed PSI-related factors considering upper instrumented vertebra (UIV) and lumbar modifier type simultaneously. Methods Patients with Lenke Type 2A AIS treated by spinal fusion were retrospectively identified and their data were extracted from six spine centers in Japan. Inclusion criteria were age between 10 and 20 years at surgery, UIV = T2, major curve 40° to 90°, and follow-up for 24 to 30 months after surgery. We analyzed patient characteristics, surgical characteristics, and preoperative and immediate-postoperative radiographic parameters. We defined patients with lower instrumented vertebra (LIV) equal or proximal to the last touching vertebra (LTV) as selective thoracic fusion (STF-LTV) and patients with LIV distal to the LTV as non-STF-LTV. t Tests, Mann-Whitney U test, χ2 tests, Fisher exact tests, and multivariate logistic regression were used for statistical analyses. Results Among the 99 consecutive patients with a mean follow-up of 25.6 months, PSI was seen in 27 (27.3%) patients immediately after and in 17 (17.2%) patients at 24 to 30 months. The univariate analysis revealed that the significant risk factors of PSI were preoperative radiographical shoulder height, non-STF-LTV, and high main thoracic curve (MTC) correction (immediate-postoperative MTC correction rate: ≥70%), with PSI incidence of 40.0%. The multivariate logistic regression analysis indicated that interaction term of non-STF-LTV and high MTC correction was an independent risk factor for PSI (non-STF-LTV and high MTC correction, odds ratio: 5.167, 95% confidence interval: 1.470-18.159, P = 0.010). Conclusion To prevent PSI in Lenke Type 2A AIS patients, surgeons should avoid the combination of non-STF-LTV and high MTC correction in those surgeries with UIV as T2.Level of Evidence: 4.

Prospective longitudinal study.The aim of this study was to evaluate long-term degenerative changes in intervertebral discs in the thoracic spine in healthy asymptomatic subjects.Longitudinal magnetic resonance imaging (MRI) studies of intervertebral disc degeneration have been reported for the cervical and lumbar but not the thoracic spine.In this longitudinal study (average follow-up 10.0 ± 0.6 years), we assessed degenerative changes in the thoracic spine of 103 volunteers (58 men) of 223 healthy volunteers in the initial MRI study of the thoracic spine (follow-up rate 46.2%). The mean age at the initial study was 45.0 ± 11.5 years (24-77 years). Initial and follow-up thoracic-spine MRIs were graded for the following 4 factors of degenerative changes: decrease in signal intensity of intervertebral disc (DSI), posterior disc protrusion (PDP), anterior compression of dura and spinal cord (AC), and disc-space narrowing (DSN) from T1-2 to T12-L1. We assessed associations between changes in MRI grade and demographical factors such as age, sex, body mass index, smoking habits, sports activities, and disc degeneration in the cervical spine.MRIs revealed that 63.1% of the subjects had degenerative changes in the thoracic intervertebral discs that had progressed at least one grade during the follow-up period. DSI progressed in 44.7% of subjects, PDP in 21.4%, and AC in 18.4% during the 10-year period. No DSN progression was seen. DSI was frequently observed in the upper thoracic spine (T1-2 to T4-5). Disc degeneration was relatively scarce in the lower thoracic spine (T9-10 to T12-L1). PDP was frequently observed in the middle thoracic spine (T5-6 toT8-9). We found significant associations between DSI and cervical-spine degeneration (P = .004) and between AC and smoking (P = .04).Progressive thoracic disc degeneration, observed in 63.1% of subjects; was significantly associated with smoking and with cervical-spine degeneration.2.

Study design Multicenter retrospective case series. Objective To report the risks, recovery, and clinical impact of neurological complications (NCs) in adult spinal deformity (ASD) surgery. Summary of background data Although recent studies have reported the incidence of NCs in ASD surgery, few have addressed the recovery from and clinical impacts of NC. Methods We reviewed records from a multicenter database for 285 consecutive surgically treated ASD patients who had reached a 2-year follow-up. NCs were categorized as sensory only or motor deficit (MD). Recovery was noted as none, partial, or complete, during hospitalization and at every postoperation visit. Uni- and multivariate risk analyses were performed to identify risk factors for MD. Results NC developed in 29 (10%) patients within 30 days of surgery, of which 11 were permanent deficits (seven no recovery, and four partial recovery). MD developed in 14 (5%) patients, including one spinal cord injury. Seven MD patients required physical assistance at the latest follow-up. While NC patients experienced significant improvements in health-related quality of life at the 2-year follow-up, the health-related quality of life was significantly worse for the NC versus no-NC group at this time point. Univariate analyses revealed that Schwab-SRS types N and L, pelvic tilt, modified frailty index physical function, and an inferior SRS22 function domain at baseline were risk factors for MD. Among them, modified frailty index physical function, which represented a preoperative decline in activities of daily living, was identified as an independent risk factor for MD (OR: 4.0, 95% CI: 1.2-13.5, P = 0.03). Conclusions NC developed in 10% of ASD surgery patients, with permanent deficits occurring in 4%. Half of the patients who developed MD required physical assistance, which contributed to the inferior clinical outcomes. Surgical intervention should be considered before severe activities of daily living decline to prevent NCs. Level of evidence 4.

A retrospective multicenter database review of 240 consecutive patients at least 21 years of age (mean 58 ± 17, range 22-79) who underwent surgery for adult spinal deformity (ASD) and were followed at least 2 years.To investigate how treatment for frailty affects complications in surgery for ASD.Several recent studies have focused on associations between frailty and surgical complications. However, it is not clear whether treating frailty affects complication rates in surgery for ASD.Patients were categorized as robust (R group), prefrail, or frail based on the modified frailty index (mFI); prefrail and frail patients were divided by good control of frailty (G group), defined as treatment following the appropriate guidelines for each mFI factor, or poorly controlled frailty (PC group). We compared clinical outcomes and perioperative and 2-year complications between the three groups.Of the 240 patients, 142 (59%) were robust, 81 (34%) were prefrail, and 17 (7%) were frail. Among the frail and prefrail patients, 71 (72%) were classified as G and 27 (28%) as PC. The perioperative complication rate was similar in the G and PC groups (32% vs. 37%) but was significantly lower in the R group (15%, P 0.01). The age- and sex-adjusted odds ratio for 2-year complications was not different in the P group when the G group was referenced (odds ratio 1.3 [0.5-3.2], P = 0.63). In the G and PC groups, which had similar 2-year outcomes, the Scoliosis Research Society-22 function and total scores were significantly lower than in the R group (function: R 3.9 ± 0.7, G 3.5 ± 0.7, P 3.3 ± 0.6; total: R 3.9 ± 0.6, 3.7 ± 0.7, 3.4 ± 0.6; P 0.01).Regardless of its treatment status, frailty increases the risk of complications and inferior clinical outcomes in ASD surgery. Surgeons should routinely evaluate frailty and inform patients of frailty-related risks when considering surgery for ASD.4.

STUDY DESIGN A multicenter retrospective case series of patients treated surgically for adult spinal deformity (ASD). OBJECTIVE The aim of this study was to compare clinical outcomes between propensity score matched ASD patients with or without drop body syndrome (DBS). SUMMARY OF BACKGROUND DATA DBS is an extreme primary sagittal-plane deformity often seen in Asian countries. Although the importance of sagittal alignment is widely recognized, surgical outcomes for deformities purely in the sagittal plane are poorly understood. METHODS This study included 243 consecutive patients (age 66 ± 17 years; range 22-78) who were treated surgically for ASD and were followed at least 2 years (mean follow-up 3.7 ± 2.3 years). DBS was defined as a primary lumbar kyphosis with PI-LL >40°, Cobb angle

STUDY DESIGN Retrospective multicenter study. OBJECTIVE We aimed to assess the outcomes following posterior cervical decompression for cervical spondylotic myelopathy (CSM) in a large sample of patients older than 80 years. SUMMARY OF BACKGROUND DATA Although age is a predictor of surgical outcomes for CSM, most previous studies have only investigated the effect of age for patients aged 65 to 75 years, and surgical outcomes remain unclear for older patients. METHODS Patients older than 50 years who underwent posterior cervical decompression for CSM were enrolled from 17 institutions. The patients were grouped into a young-old group (

STUDY DESIGN A retrospective comparative study. OBJECTIVE The aim of this study was to examine the changes in cervical sagittal alignment (CSA) following surgical correction in a patient with Lenke type 5 adolescent idiopathic scoliosis (AIS) and evaluate any possible factors influencing postoperative CSA. SUMMARY OF BACKGROUND DATA Few studies have assessed the association between CSA and thoracic or lumbar sagittal alignment in AIS patients with major thoracolumbar/lumbar curve who underwent posterior correction and fusion surgery. METHODS Sixty-six patients with Lenke type 5 AIS (two males and 64 females, the mean age at surgery of 16.2 years) were included in this study. They were followed up for minimum 5 years after surgery. Multiple linear regression analysis was used to evaluate possible factors influencing the postoperative CSA. To determine the influence of upper end vertebra (UEV) level on postoperative CSA, the subjects were divided into two groups according to UEV level of ≥T9 or ≤T10. The outcome variables were compared between the two groups and analyzed for changes in various spinal sagittal profiles using radiographic outcomes. RESULTS Multiple linear regression analysis revealed that preoperative T10-L2 kyphosis and LL were significantly correlated with postoperative C2-7 lordosis. However, CSA did not significantly change at 5 years after surgery. Sub-analysis of the cohort revealed that in the UEV ≥T9 group, the mean thoracic kyphosis significantly increased from 20.3° ± 10.6° to 24.0° ± 8.9° and the mean C2-7 lordosis also significantly increased from -12.5° ± 8.3° to -4.3° ± 10.3° at 5-year postoperatively. SRS-22 outcomes were comparable between the groups. CONCLUSION We indicated that the CSA was not influenced by surgical correction in most Lenke type 5 AIS patients. However, in a patient whose UEV was located at T9 or higher levels, CSA was influenced through the changes in thoracic kyphosis following posterior correction surgery.Level of Evidence: 4.

Retrospective review of 159 surgically treated consecutive adult symptomatic lumbar deformity (ASLD) (65 ± 9 years, female: 94%) from a multicenter database.The aim of this study was to provide a comprehensive analysis of the risk of a poor clinical outcome in ASLD surgery.Poor-risk patients with ASLD remain poorly characterized.ASLD was defined as age40 years with a lumbar curve ≥30° or C7SVA ≥5 cm and Scoliosis Research Society 22 (SRS22) pain or function4. Poor outcome was defined as 2y SRS22 total4 or pain, function or satisfaction ≤3. The outcomes of interest included age, sex, body mass index, bone mineral density, Schwab-SRS type, frailty, history of arthroplasty, upper-instrumented vertebral, lower-instrumented vertebral, levels involved, pedicle subtraction osteotomy, lumbar interbody fusion, sagittal alignment, global alignment and proportion (GAP) score, baseline SRS22r score, estimated blood loss, time of surgery, and severe adverse event (SAE). Poisson regression analyses were performed to identify the independent risks for poor clinical outcome. A patient was considered at poor risk if the number of risks was4.All SRS22 domains were significantly improved after surgery. In total, 21% (n = 34) reported satisfaction ≤3 and 29% (n = 46) reported pain or function ≤3. Poisson regression analysis revealed that frailty (odds ratio [OR]: 0.2 [0.1-0.8], P = .03), baseline mental-health (OR: 0.6 [0.4-0.9], P = .01) and function (OR: 1.9 [1.0-3.6], P .01), GAP score (OR: 4.6 [1.1-18.7], P = .03), and SAE (OR: 3.0 [1.7-5.2], P .01) were identified as independent risk for poor clinical outcome. Only 17% (n = 6) of the poor-risk patients reached SRS22 total score4.0 at 2 years.The overall clinical outcome was favorable for ASLD surgery. Poor-risk patients continue to have inferior outcomes, and alternative treatment strategies are needed to help improve outcomes in this patient population. Recognition and optimization of modifiable risk factors, such as physical function and mental health, and reduced SAEs may improve overall clinical outcomes of ASLD surgery.Level of Evidence: 3.

STUDY DESIGN A longitudinal, 20-year comparative study of patients with whiplash-associated disorders (WAD). OBJECTIVE The aim of this study was to clarify the long-term impact of WAD on patient symptoms and on magnetic resonance imaging (MRI) findings of the cervical spine, in comparison with asymptomatic volunteers. SUMMARY OF BACKGROUND DATA The long-term impact of WAD has not been fully elucidated. METHODS Between 1993 and 1996, we conducted a cross-sectional comparative study of 508 acute WAD patients and 497 asymptomatic volunteers, all of whom underwent MRI on cervical spine and physical examinations. For this 20-year follow-up comparative study, 75 WAD patients and 181 control subjects aged

STUDY DESIGN Retrospective multicenter study. OBJECTIVE The aim of this study was to identify the impact of diabetes on surgical outcomes of posterior decompression for cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA Although some previous studies have reported surgical outcomes of posterior decompression for CSM in diabetic patients, their results were inconsistent. METHODS We included 675 patients with CSM who underwent posterior decompression. Patients were divided into diabetic (n = 140) and nondiabetic (n = 535) groups according to the diabetic criteria for glucose intolerance. Surgical outcomes as assessed by the Japanese Orthopedic Association (JOA) scores and visual analog scale (VAS) for neck pain were compared between groups. Subsequently, the functional outcomes of diabetic patients were compared between the mild (n = 131) and moderately severe (n = 9) groups. All patients were followed up for at least 1 year after surgery. RESULTS Compared with the nondiabetic group, the diabetic group showed lower pre- and postoperative JOA scores (P = 0.025 and P = 0.001, respectively) and a lower JOA score recovery rate (RR) (P = 0.009). However, the preoperative-to-postoperative changes in JOA scores in the diabetic and nondiabetic groups were not significantly different (P = 0.988). Pre- and postoperative VAS for neck pain and postoperative reduction of neck pain were comparable between groups (P = 0.976, P = 0.913 and P = 0.688, respectively). Although statistical analysis was not performed due to the small underpowered sample size, functional outcomes assessed by the JOA score RR (43.3 ± 37.1% vs. 45.3 ± 33.9%) and preoperative-to-postoperative changes in JOA scores (3.0 ± 2.2 vs. 2.7 ± 2.5) were similar between the mild and moderately severe diabetes groups. CONCLUSION CSM patients with diabetes experienced improvements in neurological function and neck pain as a result of posterior decompression to the same extent seen in patients without diabetes.Level of Evidence: 3.

Multicenter retrospective study.To validate and improve the predictive model for proximal junctional failure (PJF) with or without the bone mineral density (BMD) score.PJF is a serious complication of surgery for adult spinal deformity (ASD). A predictive model for PJF was recently reported that has good accuracy, but does not include BMD, a known PJF risk factor, as a variable.We included 145 surgically treated ASD patients who were older than 50 at the time of surgery and had been followed up for at least 2 years. Variables included age, sex, body mass index (BMI), fusion level, upper and lower instrumented vertebral (UIV and LIV) level, primary or revision surgery, pedicle subtraction osteotomy (PSO), Schwab-SRS type, and BMD. PJF was defined as a ≥ 20° increase from baseline (immediately postoperative) of the proximal junctional angle with concomitant deterioration of at least 1 SRS-Schwab sagittal modifier grade, or any proximal junctional kyphosis requiring revision. Decision-making trees were constructed using the C5.0 algorithm with 10 different bootstrapped models, and validated by a 7:3 data split for training and testing; 112 patients were categorized as training and 33 as testing samples.PJF incidence was 20% in the training samples. Univariate analyses showed that BMD, BMI, pelvic tilt (PT), UIV level, and LIV level were PJF risk factors. Our predictive model was 100% accurate in the testing samples with an AUC of 1.0, indicating excellent fit. The best predictors were (strongest to weakest): PT, BMD, LIV level (pelvis), UIV level (lower thoracic), PSO, global alignment, BMI, pelvic incidence minus lumbar lordosis, and age.A successful model was developed for predicting PJF that included BMD. Our model could inform physicians about patients with a high risk of developing PJF in the perioperative period.4.

Study design Single-center retrospective analysis of consecutively collected data. Objective To determine the clinical characteristics of idiopathic spinal epidural lipomatosis (SEL). Summary of background data SEL is associated with the overt accumulation of nonencapsulated adipose tissue in the epidural space, leading to spinal cord or nerve root compression. The etiology of this condition is currently not completely understood. Methods Data of 166 male patients who underwent primary surgery for lumbar spinal canal stenosis (LSS) from May 2013 to February 2016 were retrospectively reviewed. Participants were divided into three groups based on the degree of epidural lipomatous lesion. Patient data of age at surgery, body mass index, prevalence of common noncommunicable diseases, blood tests, arteriosclerotic index, and preoperative clinical scores (assessed using the Japanese Orthopedic Association Back Pain Evaluation Questionnaire) were evaluated. Multivariate analysis was performed to assess the potential associated factors for idiopathic SEL. Results Patients with LSS with severe SEL had a significantly higher body mass index and elevated serum levels of total cholesterol and triglyceride compared with those without SEL. Analysis of preoperative clinical scores revealed that patients with SEL experienced pain more frequently and showed less walking ability than did those without SEL. Multivariate analysis revealed that hyperlipidemia was significantly associated with idiopathic SEL (odds ratio = 3.74, 95% confidence interval = 1.31-10.64). Conclusion Our data suggest that aberrant lipid metabolism is related to the pathogenesis of idiopathic SEL and that patients with LSS with idiopathic SEL have more severe pain than do those without SEL. Level of evidence 3.

Genetic case-control study of single nucleotide polymorphisms (SNPs).To examine the association of previously reported susceptibility genes for adolescent idiopathic scoliosis (AIS) and intervertebral disc (IVD) degeneration with adult spinal deformity (ASD).ASD is a spinal deformity that develops and progresses with age. Its etiology is unclear. Several ASD susceptibility genes were recently reported using a candidate gene approach; however, the sample sizes were small and associations with ASD development were not determined.ASD was defined as structural scoliosis with a Cobb angle more than 15° on standing radiographs, taken of patients at age 40 to 75 years in this study. Subjects in whom scoliosis was diagnosed before age 20 were excluded. We recruited 356 Japanese ASD subjects and 3341 healthy controls for case-control association studies of previously reported SNPs. We genotyped four known AIS-associated SNPs (rs11190870 in LBX1, rs6570507 in GPR126, rs10738445 in BNC2, and rs6137473 in PAX1) and three IVD degeneration-associated SNPs (rs1245582 in CHST3, rs2073711 in CILP, and rs1676486 in COL11A1) by the Invader assay.Among the AIS-associated SNPs, rs11190870 and rs6137473 showed strong and nominal associations with ASD (P = 1.44 × 10, 1.00 × 10, respectively). Of the IVD degeneration-associated SNPs, rs1245582 and rs2073711 showed no association with ASD, while rs1676486 showed a nominal association (P = 1.10 × 10). In a subgroup analysis, rs11190870 was significantly associated with a Cobb angle more than 20° in the minor thoracic curve (P = 1.44 × 10) and with a left convex lumbar curve (P = 6.70 × 10), and nominally associated with an apical vertebra higher than L1 (P = 1.80 × 10).rs11190870 in LBX1, a strong susceptibility SNP for AIS, may also be a susceptibility SNP for ASD. Thus, ASD and AIS may share a common genetic background.4.

Study design This investigation consisted of a cross-sectional study and a retrospective multicenter case series. Objective This investigation sought to identify the ideal lumbar lordosis (LL) angle for restoring an optimal pelvic tilt (PT) in patients with adult spinal deformity (ASD). Summary of background data To achieve successful corrective fusion in ASD patients with sagittal imbalance, it is essential to correct the sagittal spinal alignment and obtain a suitable pelvic inclination. We determined the LL angle that would restore the optimal PT following ASD surgery. Methods The cross-sectional study included 184 elderly volunteers (mean age 64 years) with an Oswestry Disability Index score less than 20%. The relationship between PT or LL and the pelvic incidence (PI) in normal individuals was investigated. The second study included 116 ASD patients (mean age 66 years) who underwent thoracolumbar corrective fusion at 1 of 4 spine centers. The postoperative PT values were calculated using the parameters measured. On the basis of these studies, an ideal LL angle was determined. Results In the cross-sectional study, the linear regression equation for the optimal PT as a function of PI was "optimal PT = 0.47 × PI - 7.5." In the second study, the postoperative PT was determined as a function of PI and corrected LL, using the equation "postoperative PT = 0.7 × PI - 0.5 × corrected LL + 8.1." The target LL angle was determined by mathematically equalizing the PTs of these 2 equations: "target LL = 0.45 × PI + 31.8." Conclusion The ideal LL angle can be determined using the equation "LL = 0.45 × PI + 31.8," which can be used as a reference during surgical planning in ASD cases. Level of evidence 4.

Prospective, multicenter, nationwide study.To investigate perioperative complications and risk factors in surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL) using data from the registry of the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament.There is no prospective multicenter study of surgical complications and risk factors for T-OPLL, and previous multicenter retrospective studies have lacked details.Surgical methods, preoperative radiographic findings, pre- and postoperative thoracic myelopathy (Japanese Orthopaedic Association [JOA] score), prone and supine position test (PST), intraoperative ultrasonography, and intraoperative neurophysiological monitoring (IONM) were investigated prospectively in 115 cases (males: 55, females: 60, average age 53.1 y). Factors related to perioperative complications and risk factors for postoperative motor palsy were identified.Posterior decompression and fusion with instrumentation with or without dekyphosis was performed in 85 cases (74%). The JOA recovery rate at 1 year after surgery in all cases was 55%. Motor palsy occurred postoperatively in 37 cases (32.2%), with a mean recovery period of 2.7 months. A long recovery period for postoperative motor palsy was significantly associated with a high number of T-OPLL levels (P 0.0001), lower preoperative JOA score (P 0.05), and greater estimated blood loss (P 0.05). Perioperative complications or postoperative motor palsy were significantly related to a higher number of T-OPLL levels, comorbid ossification of ligamentum flavum rate, lower preoperative JOA score, higher preoperative positive PST rate, more surgical invasiveness, a lower rate of intraoperative spinal cord floating in ultrasonography, and higher rate of deterioration of IONM.This study firstly demonstrated the perioperative complications with high postoperative motor palsy rate in a nationwide multicenter prospective study. Surgical outcomes for T-OPLL should be improved by identifying and preventing perioperative complications with significant risk factors.3.

STUDY DESIGN Retrospective review of surgically treated 481 adult patients with spinal disorders. OBJECTIVE The aim of this study was to elucidate the effect of frailty and comorbidities on postoperative health-related quality of life (HRQoL) and complication rates. SUMMARY OF BACKGROUND DATA Elective surgeries for spinal disorders not only improve clinical outcomes but also have high complication rates. METHODS We retrospectively reviewed the results of consecutive elective spine surgeries for 156 adult spinal deformities (ASDs: 65 ± 9 years), 152 degenerative spondylolisthesis (DS: 64 ± 10 years), or 173 lumbar spinal canal stenosis (LSCS: 71 ± 9 years) with follow-up of at least 2 years. Modified Frailty Index (mFI) and Charlson Comorbidity Index (CCI) were determined from baseline demographics. We compared the prevalence and the influence of mFI and CCI on postoperative outcomes and complication rates. RESULTS The mFI and CCI were significantly worse in ASD than in others (mFI: ASD 0.09 ± 0.12, DS 0.06 ± 0.06, LSCS 0.04 ± 0.05, P

Case-only study.The aim of this study was to confirm the association of rs11190870 with adolescent idiopathic scoliosis (AIS) severity in Japanese patients with AIS.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.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 angle30°). 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.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).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.4.

A propensity-matched comparison of risk factors for proximal junctional failure (PJF), which is a symptomatic proximal junctional kyphosis developing after corrective surgery for adult spinal deformity (ASD).To elucidate the role of bone strength for developing PJF.PJF, a devastating complication of corrective surgery for ASD, often recurs even after revision surgery. Most studies of risk factors for PJF are retrospective and have a selection bias in surgical strategy, making it difficult to identify modifiable PJF risk factors.We conducted propensity-matched comparisons of 113 surgically treated ASD patients who were followed for at least 2 years, to elucidate whether low bone-mineral density (BMD) was a true risk factor for PJF in a uniform population from a multicenter database. Patients were grouped as having mildly low to normal BMD (M group; T-score≧ - 1.5) or significantly low BMD (S group; T-score -1.5), and were propensity-matched for age, upper and lower instrumented vertebrae, history of spine surgery, and Schwab-Scoliosis Research Society (SRS) ASD classification. PJF was defined as a ≥20° increase from the baseline proximal junction angle with a concomitant deterioration of at least one SRS-Schwab sagittal modifier grade, or any type of proximal junctional kyphosis requiring revision.PJF developed in 22 of 113 patients (19%). There were 48 propensity-matched patients in the M and S groups (24 in each) with similar parameters for age, body mass index, number of vertebrae involved, C7SVA, pelvic incidence - LL, and SRS-Schwab type. In this propensity-matched population, the incidence of PJF was significantly higher in the S group (33% vs. 8%, P 0.01, odds ratio 6.4, 95% CI: 1.2-32.3).Low BMD was a significant risk factor for PJF in this propensity-matched cohort (odds ratio 6.4). Surgeons should consider prophylactic treatments when correcting ASD in patients with low BMD.3.

STUDY DESIGN Retrospective review of adult spinal deformity patients in a multiethnic database. OBJECTIVE To investigate the role of ethnicity on recruitment of compensatory mechanisms for sagittal spinal deformity. SUMMARY OF BACKGROUND DATA While the impacts of age, sex, and pelvic morphology on the ability to compensate for sagittal malalignment have been investigated, the role of ethnicity in compensatory mechanism recruitment is poorly understood. METHODS Patients from USA (85% Caucasian) >25 y/o were propensity matched by age, sex, and pelvic incidence with patients from Korea and Japan. Only primary patients or those with existing fusion below T12 were retained for analysis. Groups were subclassified by deformity severity (aligned: sagittal vertical axis (SVA) 100 mm). Radiographic measurements including pelvic retroversion, thoracic kyphosis, loss of lumbar lordosis (PI minus LL), cervical lordosis, and cervical SVA were compared between the groups. RESULTS There were 288 patients (96 each in USA, KOR, JPN), with similar age (64-67 yr) and PI (49-53°). USA had smaller pelvic incidence minus lumbar lordosis in every alignment group (P

Study design A retrospective, observational, and multicenter study. Objective To identify the ideal lower instrumented vertebra (LIV) to prevent distal adding-on after surgical correction of Lenke type 2A curve. Summary of background data LIV level may affect the risk of postsurgical adding-on. The choice of the last touching vertebra (LTV)-the most caudal vertebra of the main thoracic curve that touches the central sacral vertical line when standing-as an appropriate LIV has been validated for Lenke type 1A but not type 2A curve. Methods Radiographs obtained before, immediately after, and 2 years after surgery were evaluated for 116 consecutive patients who underwent posterior thoracic fusion surgery for Lenke type 2A curve. The LIV was proximal to the LTV in 18 patients (PLTV), distal in 43 (DLTV), and at the LTV in 55 (ALTV). Significant independent factors associated with adding-on were analyzed first by univariate analysis, and then by stepwise logistic regression analysis. Results Distal adding-on was present in 16 patients (13.8%) at follow-up: 9 PLTV (50.0%), 3 DLTV (7.0%), and 4 ALTV (7.3%). Adding-on was significantly more common in the PLTV group. One PLTV-group patient required revision surgery to treat adding-on. Univariate analysis identified the following significant factors associated with adding-on: the T2-T5 kyphosis angle and shoulder height before, immediately after, and 2 years after surgery; the lumbar Cobb angle at the 2-year follow-up; the 2-year postoperative lumbar curve correction rate; and the difference between the LIV and the end vertebra, neutral vertebra, and LTV levels. Significant independent risk factors identified by stepwise logistic regression analysis included the clavicle angle at follow-up, the correction rate of the lumbar curve immediately after surgery, and the difference between the LIV and LTV levels. Conclusion A LIV at or distal to the LTV may prevent postoperative adding-on in Lenke type 2A curve. Level of evidence 3.

STUDY DESIGN A genetic association study of single nucleotide polymorphisms (SNPs) previously reported to be associated with curve progression of adolescent idiopathic scoliosis (AIS). OBJECTIVE To determine whether the association of 5 SNPs with curve progression reported in Chinese with AIS are replicated in Japanese patients with AIS. SUMMARY OF BACKGROUND DATA AIS is a common spinal deformity and has a strong genetic predisposition. Predicting curve progression is important in clinical practice. The progression of AIS is reported to be associated with a number of genes. Associations with neurotrophin 3, G protein-coupled estrogen receptor, and tissue inhibitor of metalloproteinase 2 have been reported in Han Chinese with AIS; however, there has been no replication study for them. METHODS We recruited 2117 patients with AIS with a Cobb angle of 10° or greater of scoliosis curves. They were grouped into progression and nonprogression groups according to their scoliosis curves. Patients whose scoliotic curves were 40° or greater were included in the progression group, and those whose scoliotic curves were less than 30° and had reached skeletal maturation in the nonprogression group. We evaluated the association of 5 SNPs (rs11063714 in neurotrophin 3, rs3808351, rs10269151, and rs4266553 in G protein-coupled estrogen receptor, and rs8179090 in tissue inhibitor of metalloproteinase 2 with curve progression by comparing risk allele frequencies between the 2 groups and the mean Cobb angle for each genotype. RESULTS We evaluated the progression (N = 880) and nonprogression (N = 492) subjects, and their risk allele frequencies were not significantly different. The mean Cobb angle for each genotype also did not have statistical difference. We found no replication of the association on AIS curve progression in any of the SNPs. CONCLUSION The associations of the 5 SNPs with progression of AIS curve are not definite. Large-scale association studies based on appropriate criteria for progression would be necessary to identify SNPs associated with the curve progression.

Study design Laboratory study. Objective To elucidate the potential involvement of the interleukin-6 (IL-6)/Janus kinase (JAK)/signal transducers and activator of transcription (STAT3) pathway in the development of intervertebral disc (IVD) degeneration. Summary of background data IL-6 plays a crucial role in IVD degeneration; however, the downstream intracellular signaling of IL-6 in the IVD is not fully understood. Methods The expression levels of IL-6 and suppressors of cytokine signaling 3 (SOCS3), a target gene of the IL-6/JAK/STAT3 pathway, were evaluated in rat and human degenerated IVD samples. The effects of IL-6 on primary rat annulus fibrosus (AF) cells were analyzed using quantitative PCR, immunocytochemistry, and Western blotting. The potential efficacy of a JAK inhibitor, CP690,550, in neutralizing the effect of IL-6 was evaluated in vitro. Results A high expression of IL-6 and SOCS3 was observed in both rat and human degenerated IVD samples. In rat AF cells, IL-6 markedly induced the phosphorylation of STAT3 and the expression of cyclooxygenase-2 and matrix metalloprotease-13. CP690,550 significantly suppressed the phosphorylation of STAT3 and offset the catabolic effect of IL-6 in rat AF cells. Conclusion Our results suggest that the IL-6/JAK/STAT3 pathway is involved in the pathogenesis of IVD degeneration and that CP690,550 suppresses the catabolic effect of the IL-6 in the IVD. Level of evidence N/A.

STUDY DESIGN Case report and systematic review of the literature. OBJECTIVE To describe a rare case of remodeling of the cervical facet joint after the microendoscopic resection of an osteoid osteoma. SUMMARY OF BACKGROUND DATA Osteoid osteoma, the third most common benign bone tumor, is often treated by image-guided percutaneous removal of the nidus. However, percutaneous resection poses technical difficulties when the tumor is located near the spinal cord or nerve roots. To our knowledge, there are no reports describing postoperative remodeling of the cervical facet joint after surgical resection of an osteoid osteoma. METHODS A 13-year-old boy was presented with neck pain that became worse at night. Computed tomography showed an osteoid osteoma in the right 7th cervical superior articular process. We successfully resected the nidus of the osteoid osteoma using minimally invasive microendoscopy. RESULTS The patient was symptom-free at the 1-year follow up, and computed tomography images showed new bone formation at the C6/7 facet joint. CONCLUSION This case indicates that microendoscopic resection is safe and effective for treating a cervical osteoid osteoma. This technique allowed total resection of the nidus with only minimal damage to the adjacent soft tissue and bone, and induced remodeling of the resection site.Level of Evidence: 4.

Study design Multicenter case-control study. Objective To characterize the pathogenesis of idiopathic spinal epidural lipomatosis (SEL). Summary of background data SEL is often associated with the history of steroid use or endocrine disorders; however, the pathogenesis of idiopathic SEL remains poorly understood. Methods Sixteen patients who underwent lumbar decompression surgery due to severe idiopathic SEL were included in the study (L group, 15 men and 1 woman; mean age, 71.5 yrs). Fifteen patients without SEL, who underwent decompression surgery for lumbar canal stenosis, were selected as controls (C group, 14 men and 1 woman; mean age, 70.3 yrs). The following parameters were analyzed in these two groups: body mass index (BMI), medical history, histology, the size of adipocytes in the epidural fat (EF) tissues, and the expression level of the transcripts for adiponectin, leptin, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and IL-8. Results The mean BMI of the L group was significantly higher than that of the C group (29.1 vs. 25.2 kg/m, P = 0.006), and there was a significant correlation between BMI and the width of EF in both groups. The average adipocyte size in the EF was significantly larger in the L group than in the C group (2846.8 vs. 1699.0 μm, P = 0.017). Furthermore, the expression levels of the transcripts for TNF-α and IL-1β in the L group were significantly higher than those in the C group [2.59-fold increase (P = 0.023) and 2.60-fold increase (P = 0.015), respectively]. Conclusion Our data suggest that the pathogenesis of idiopathic SEL is associated with obesity. In addition, the increased expression of two major inflammatory cytokines in the EF in the L group may indicate that SEL is causally related to chronic inflammation. Level of evidence 3.

Study design Retrospective case series. Objective To evaluate the treatment strategies for spinal meningioma. Summary of background data Although previous studies have demonstrated favorable surgical outcomes for spinal meningioma, with a low incidence of tumor recurrence, few have examined long-term surgical outcomes. Methods The influence of patient age, surgical margin status (Simpson grade), tumor location, and histological subtype on tumor recurrence were examined retrospectively. In addition, the resected dura mater from Simpson grade I cases was examined for invasive tumor cells and compared with the presence or absence of a dural tail sign on magnetic resonance image. Results Complete resection (Simpson grades I and II) was performed in 62 patients. Among them, the tumor recurrence rate was 9.7%, all in patients who underwent grade II resection for ventral spinal lesions. The mean duration to reoperation in these patients was 12.2 ± 5.2 years. Of the 6 patients who underwent incomplete resection (Simpson grade III/IV), all required reoperation for tumor recurrence or regrowth, 5 years later on average. Patients younger than 50 years at the initial surgery had a significantly higher recurrence rate than those aged 50 years or older. Histologic examination of 43 dura mater specimens from Simpson grade I-resection patients revealed tumor cell invasion between the inner and outer layers in 15 patients. This invasion was noted in 8 (29%) of 28 patients who were negative for the dural tail sign on magnetic resonance image, and in 7 (47%) of 15 patients who showed a positive dural tail sign. The MIB-1 index reached about 10% for dumbbell-type meningiomas invading the vertebral body; these were associated with repeated recurrence and unfavorable prognosis. Conclusion Long-term follow-up after surgery for meningiomas indicated that Simpson grade I resection should be selected whenever practicable when treating younger patients or dumbbell-type meningiomas. Tumors recurred at 12 years, on average, in approximately 30% of patients who underwent grade II resection.

Study design Retrospective case series of chronic atlantoaxial rotatory fixation (AARF) treated by a novel closed reduction method (remodeling therapy) and review of the literature. Objective To describe clinical features of chronic AARF and the rationale of the remodeling therapy. Summary of background data Treatment strategy for chronic recurrent AARF remains controversial. Posterior C1-C2 arthrodesis has been widely used for recurrent unstable AARFs after the closed reduction, and a variety of posterior fusion techniques have been advocated. In contrast, several investigators reported a chronic AARF case treated by a simple traction or closed reduction followed by cervical immobilization. Previously, we have found that a deformity of the superior C2 facet joint (C2 facet deformity) on three dimensional computed tomography (3D CT) reconstructions is a risk factor for recurrent subluxation. In addition, the remodeling of this C2 facet deformity by careful closed manipulation followed by halo fixation (remodeling therapy) could prevent the recurrence of subluxation. Methods Twelve children with chronic AARF who sustained torticollis for an average of 4.4 months after the onset were referred to our clinic. The mean age at the initial visit was 7.8 years. All patients underwent the remodeling therapy as reported previously. Radiographic findings and clinical courses were retrospectively reviewed. Treatment methodology, pearls, and pitfalls of the remodeling therapy were discussed with review of the literature. Results 3D CT images before reduction revealed persistent atlantoaxial subluxation and the C2 facet deformity in the dislocated side in all cases. Follow-up 3D CT scans demonstrated the remodeling of the C2 facet deformity at an average of 2.4 months after successful reduction of subluxation. Neither recurrence of symptoms nor subluxation was observed at a mean follow-up of 42 months in any case. The cervical range of motion was 73.9° at the dislocated and 83.5° at the contra-dislocated side from the midline. Conclusion Chronic irreducible and recurrent unstable AARF should be initially managed by remodeling therapy using the facet deformity sign as a clinical index, if the C1 and C2 have not been osseously fused.

Study design Review article. Objective To discuss the history, indication, surgical outcomes, prognostic factors, and complications of laminoplasty for ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. Summary of background data OPLL usually requires surgery, which often involves indirect decompression by the posterior approach. Of the posterior procedures for OPLL, laminoplasty is the favored treatment. Here, we review the previously published literature on laminoplasty for OPLL. Methods PubMed and previously published English and Japanese book chapters were searched for posterior procedures for treating OPLL. Results There is a large body of literature on OPLL and its treatment. Based on a review of the literature, the history, indication, surgical outcomes, prognostic factors, and complications of laminoplasty for OPLL were examined. The results showed that long-term outcomes of both the open-door and double-door types of laminoplasty are favorable, although late neurological deterioration occurs in some patients. Preoperative kyphosis of the cervical spine and severe (>60%) compromise of the spinal canal by OPLL appear to be the limiting factors for the indication of laminoplasty. Complications of laminoplasty include segmental motor palsy, lamina closure, and axial symptoms. Conclusion Laminoplasty is a feasible surgical option for OPLL if candidate patients are appropriately selected.

Study Design. Prospective clinical series. Objective. To determine how many thoracic scoliotic pedicles have cancellous versus cortical versus absent channels. Summary of Background Data. Although morphologic evaluations of thoracic pedicles have been well reported, the results do not practically reflect clinical findings during actual pedicle screw placement. We propose a novel pedicle channel classification describing the osseous anatomy encountered during pedicle probe insertion. Methods. We noted 4 pedicle types in 53 consecutive scoliosis patients. Type A: pedicle probe smoothly inserted without difficulty; the morphology is described as a "Large Cancellous Channel." Type B: pedicle probe inserted snugly with increased force; described as a "Small Cancellous Channel." Type C: pedicle probe cannot be manually pushed but must be tapped with a mallet down the pedicle into the body; described as a "Cortical Channel." Type D: pedicle probe cannot locate a channel thus necessitating a "juxtapedicular" screw position; described as a "Slit/Absent Channel." The average age at time of surgery was 23.4 ± 16.7 years. Diagnoses included idiopathic scoliosis (n = 38) and syndromic scoliosis (n = 15). The average main thoracic Cobb angle was 73° ± 26°. Evaluation of pedicle morphology of the 4 types was also performed in 21 consecutive cases of adolescent idiopathic scoliosis using preoperative computed tomography images. Results. A total of 1021 pedicles with screws placed were evaluated. The average percent per type was as follows: 61.0% type A; 29.2% type B, 6.8% type C, and 3.0% type D. On the convexity, 98.2% of pedicles were type A or B versus 81.5% on the concavity (P < 0.05). There were significant differences between adolescent versus adult idiopathic scoliosis (P = 0.007), and syndromic scoliosis versus adult idiopathic scoliosis (P = 0.017) regarding pedicle morphologic proportions. There was a significant tendency toward a decrease in the proportion of type A pedicles, an increase in the proportion of type B pedicles as the Cobb angle increased (P < 0.0001). Evaluation based on 312 thoracic pedicles in 21 consecutive adolescent idiopathic scoliosis patients using preoperative computed tomography axial images confirmed assumptions of the 4 pedicle types. Conclusion. We propose a classification for pedicle channels describing the osseous anatomy encountered during pedicle probe insertion. Based on the classification, surprisingly, we found during surgery that 90% of thoracic pedicles had a cancellous channel, whereas 7% had a cortical channel and only 3% had an absent channel.

Study Design. Case report. Objective. To report 3 cases of malignant tumors in the upper cervical spine that were treated surgically by a combination of posterior tumor resection and stabilization and anterior tumor resection through a mandible-splitting approach after failed ion-beam radiation therapy. Summary of Background Data. Few clinical reports have described in detail the postoperative complications associated with transoral surgical resection of tumors in the upper cervical spine after unsuccessful ion-beam radiation therapy. Methods. Three patients with malignant tumors in the upper cervical spine who had undergone ion-beam radiotherapy and experienced tumor recurrence were treated by a combination of posterior and anterior surgery through a mandible-splitting approach. One patient (patient 1, a 32-year-old man) had a hemangioendothelioma at the C2 and C3 level, whereas the other 2 patients (patient 2, a 66-year-old woman and patient 3, a 65-year-old man) had a chordoma at the C2 and C3 level. Results. The intralesional but macroscopic total resection of the tumors was achieved in all 3 patients. However, serious complications developed after surgery, including deep wound infection, cerebrospinal fluid leakage, and meningitis in patient 1, prolonged swallowing difficulty, subsidence of the strut graft, and recurrence in patient 2, and deep wound infection and discitis causing progressive paralysis in patient 3. All patients underwent salvage surgery, including debridement of the wound in patient 1, posterior reinforcement using instrumentation and posterior tumor resection for the recurrent tumor in patient 2, and anterior debridement of the wound with a pedicle flap using the pectoral major muscle in patient 3 to address these problems. Patients 1 and 3 had no signs of recurrence at the time of a follow-up examination. Conclusion. Severe complications, mainly associated with the disturbance in healing of the retropharyngeal wall, were observed in all 3 patients. A preventive method, such as primary repair of the retropharyngeal wall using muscular/musculocutaneous flaps, should be considered for patients undergoing resection through a transoral approach after ion-beam irradiation.

STUDY DESIGN.: A case report. OBJECTIVES.: To report a case of progressive kyphoscoliosis associated with a tethered cord that was corrected by posterior vertebral column resection after complicated untethering surgery. SUMMARY OF BACKGROUND DATA.: There have been few clinical reports on posterior vertebral column resection conducted for severe deformity associated with a tethered cord. METHODS.: A patient with progressive kyphoscoliosis associated with a tethered cord first underwent untethering surgery, resulting in neurologic deterioration. Posterior vertebral column resection was performed to correct the kyphoscoliosis while shortening the spinal column to prevent the spinal cord from stretch injury. RESULTS.: Good correction of kyphoscoliosis was obtained without further neurologic deterioration. The Cobb angles of scoliosis was 103 degrees before surgery and 25 degrees after surgery (correction rate; 75.7%), and that of kyphosis was 90 degrees and 36 degrees , respectively (correction rate; 60.0%). CONCLUSION.: Correction of progressive kyphoscoliosis associated with a tethered cord can be achieved successfully by posterior vertebral column resection even after complicated untethering surgery.