Published papers

© 2017, The Author(s). Purpose: Hinge-like hyper-mobility is occasionally observed at the atlanto-occipital (O-C1) joint. However, it has not been clear if this kind of hinge-like hyper-mobility at the O-C1 joint should be regarded as “pathologic”, or referred to as “instability”. To solve this issue, we aimed to establish a reliable radiographic assessment method for this specific type of O-C1 instability and figure out the “standard value” for the range of motion (ROM) of the O-C1 joint. Methods: To figure out the standard range of the O-C1 angle, we acquired magnetic resonance imaging (MRI) sagittal views of the cervical spine for 157 healthy volunteers [average: 37.4 year-old (yo)] without spine diseases, at neutral, maximum flexion and maximum extension positions. Results: The average value (AVE) for ROM of O-C1 angle was 9.91°. The standard value for ROM of O-C1 angle was calculated as 0°–21°. There was no statistically significant gender difference. We also found that the older population (≧ 40 yo) significantly had a larger ROM of O-C1 angle (AVE: 11.72°) compared to the younger population (< 40 yo) (AVE: 8.99°). Conclusions: We consider that hinge-like instability at O-C1 joint, which cannot be assessed by measuring Powers ratio, can be assessed by measuring the range of O-C1 angles using dynamic-MRI. Evaluation of O-C1 instability is important especially when we perform surgical treatment for diseases with upper cervical instability (such as retro-odontoid pseudotumor). We consider that the current study provides important information in such a case.

Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved. Study Design. Multicenter retrospective study. Objective. To validate and improve the predictive model for proximal junctional failure (PJF) with or without the bone mineral density (BMD) score. Summary of Background Data. 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. Methods. 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. Results. 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. Conclusion. 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. Level of Evidence: 4.

© 2018 Wolters Kluwer Health, Inc. 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.

© The Author(s) 2018. Published by Oxford University Press. All rights reserved. Adolescent idiopathic scoliosis (AIS) is the most common musculoskeletal disorder of childhood development. The genetic architecture of AIS is complex, and the great majority of risk factors are undiscovered. To identify new AIS susceptibility loci, we conducted the first genome-wide meta-analysis of AIS genome-wide association studies, including 7956 cases and 88 459 controls from 3 ancestral groups. Three novel loci that surpassed genome-wide significance were uncovered in intragenic regions of the CDH13 (P-value_rs4513093 = 1.7E-15), ABO (P-value_ rs687621 = 7.3E-10) and SOX6 (P-value_ rs1455114 = 2.98E-08) genes. Restricting the analysis to females improved the associations at multiple loci, most notably with variants within CDH13 despite the reduction in sample size. Genome-wide gene-functional enrichment analysis identified significant perturbation of pathways involving cartilage and connective tissue development. Expression of both SOX6 and CDH13 was detected in cartilage chondrocytes and chromatin immunoprecipitation sequencing experiments in that tissue revealed multiple HeK27ac-positive peaks overlapping associated loci. Our results further define the genetic architecture of AIS and highlight the importance of vertebral cartilage development in its pathogenesis.

STUDY DESIGN: A retrospective study. OBJECTIVE: To identify the radiographic differences between Chinese and Japanese patients with cervical ossification of the posterior longitudinal ligament (OPLL) using computed tomography (CT) and magnetic resonance imaging (MRI), and to compare the characteristics of OPLL between the two nationalities. SUMMARY OF BACKGROUND DATA: OPLL has a high prevalence in East Asia. However, the differences between Chinese and Japanese OPLL patients are poorly known. METHODS: This was a retrospective study of Chinese (n = 300) and Japanese (n = 102) consecutive patients who received a diagnosis of cervical OPLL between January 2010 and December 2014. All patients underwent CT and MRI. The type and distribution of OPLL were determined. Spinal compression was assessed by MRI. OPLL type, distribution, comorbidity, and compression of the spinal cord were examined. The ossification index (OP-index) was used to evaluate the OPLL. Factors contributing to the OP-index were examined by multivariate analysis. RESULTS: The Chinese patients were younger than the Japanese patients (P < 0.0001), and there were more women among the Chinese patients (P = 0.0002). The OP-index was higher among the Japanese patients (median, 5 vs. 4, P = 0.003). Among men, OPLL lesions were more frequent in the under 55-year-old Japanese at C7 (P = 0.04), in the 55 to 64-year-old Japanese at C4, C5, and C6 (all P < 0.05), and in the over 64-year-old Japanese at C3/4 (P = 0.01), compared with their Chinese counterparts. Among women, OPLL lesions were more frequent in the 55 to 64-year-old Japanese at C6 (P = 0.04). The multivariate analysis showed that only age was independently associated with the OP-index (odds ratio [OR] = 1.023, 95% confidence interval [CI]: 1.002-1.045, P = 0.034). CONCLUSION: Japanese patients had a higher frequency of OPLL lesions at C5, C6, and C7. Age was independently associated with OPLL.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 < 0.01. CCI: ASD 2.1 ± 1.6, DS 1.4 ± 0.7, LSCS 1.6 ± 0.9, P < 0.01). Postoperative HRQoL deteriorated as mFI worsened in ASD (nofrail: Oswestry Disability Index [ODI] 26 ± 11, Scoliosis Research Society Questionnaire [SRS] 3.7 ± 0.7; prefrail: ODI 32 ± 12, SRS 3.6 ± 0.6; frail: ODI 42 ± 15, SRS 3.2 ± 0.7). In DS and LSCS, however, SF-36 physical component score and mental component score improved regardless of mFI and CCI. The 2-year major complications rate increased with frailty (36%, 58%, and 81%) in ASD, but not in others. CONCLUSION: ASDs were more frail and had more comorbidities than the other populations. In ASD, postsurgical outcomes and complication rates deteriorated as frailty and CCI increased, whereas surgery produced favorable outcomes and acceptable complication rates in DS and LSCS regardless of frailty and CCI. Careful patient selection and treatment of comorbidities before surgery may decrease complications and improve outcomes for the surgical treatment of ASD.4.

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: Potential associations between radiographic parameters and the incidence of symptomatic postoperative spinal epidural hematoma (PSEH) have not been identified. This study aimed to identify risk factors including radiographic parameters for symptomatic PSEH after posterior decompression surgery for lumbar spinal canal stenosis (LSS). Methods: We retrospectively reviewed 1007 consecutive patients who underwent lumbar decompression surgery for lumbar spinal canal stenosis (LSS) at our institution. We identified 35 cases of symptomatic PSEH, defined by clinical symptoms and MRI findings, and selected 3 or 4 age- and sex-matched control subjects for each PSEH subject (124 controls). We compared radiographic parameters and previously reported risk factors between PSEH and control subjects. Results: Compared to the control group, PSEH patients had significantly higher preoperative systolic (p =.020) and diastolic (p =.048) blood pressure, and more levels of decompression (p =.001). PSEH and control subjects had significant differences in lumbar lordosis (PSEH 24.8° ± 14.6°, control 34.8° ± 14.5°), pelvic tilt (25.1° ± 11.7° vs. 20.8° ± 8.4°), sacral slope (23.4° ± 9.4° vs. 27.6° ± 8.3°), and pelvic incidence minus lumbar lordosis (23.7° ± 15.0° vs. 13.7° ± 14.6°). Multivariate analysis revealed two significant risk factors for PSEH: decompression of two or more levels and lumbar lordosis < 25°. Conclusions: Multilevel decompression and hypolordosis are significant risk factors for symptomatic PSEH after decompression surgery for LSS. LSS patients with lumbar hypolordosis or multilevel stenosis should be carefully observed for PSEH after decompression surgery. Graphical abstract: These slides can be retrieved under Electronic Supplementary Material.[Figure not available: see fulltext.].

Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved. Study Design. 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). Objective. To elucidate the role of bone strength for developing PJF. Summary of Background Data. 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. Methods. 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. Results. 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). Conclusion. 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. Level of Evidence: 3

Postoperative neck pain has been reported as an unsolved postoperative complication of surgery for cervical ossification of the posterior longitudinal ligament (OPLL). The aim of the present study was to elucidate factors having a significant association with postoperative deterioration of neck pain in cervical OPLL patients. We studied a cohort of patients in a prospective registry of 478 patients who had undergone cervical spine surgery for cervical OPLL. We excluded those without evaluation of preoperative neck pain. Therefore, 438 patients were included in the present study. Neck pain was evaluated with the visual analogue scale (VAS, 0–100 mm). Postoperative neck pain deterioration was defined as a ≥20 mm increase of VAS neck pain. Patient factors, neurological status, imaging factors and surgical factors were assessed. Univariate analyses followed by multivariate analysis using stepwise logistic regression was performed. Six months after surgery, 50 (11.6%) patients showed postoperative neck pain deterioration and 76 (17.4%) patients showed postoperative neck pain deterioration 2 years after surgery. Six months after surgery, the rate of neck pain deterioration was significantly higher in patients who had undergone posterior surgery. Two years after surgery, the number of levels fused was significantly correlated with neck pain deterioration.

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

CASE: Gorham-Stout disease (GSD) is a rare disorder characterized by progressive localized osteolysis and lymphatic malformation. A 26-year-old woman with GSD presented to our hospital with a Cobb angle of 100° and a kyphosis angle of 88°. Everolimus therapy was initiated to control the disease prior to surgery. After halo-gravity traction for 4 weeks, we performed anterior and posterior spinal fusion. Postoperative computed tomography revealed satisfactory bone union and no significant loss of correction 1 year post-surgery. CONCLUSION: This case suggests that anterior and posterior spinal fusion combined with everolimus therapy can be a therapeutic option for GSD.

Introduction: Of the 23 cases of spinal intradural-extramedullary ependymomas which have been reported to date, 11 were diagnosed as anaplastic. Here we present a very rare case of a thoracic intradural-extramedullary (not intramedullary) anaplastic ependymoma in an adult along with a literature review. Case presentation: A 29-year-old man presented with rapidly progressive gait disturbance, a sensory-deficit below the trunk and urination disorders that had begun a few months earlier. Magnetic resonance imaging of his thoracic spine revealed a dorsal-located intradural-extramedullary tumor at T4-5. The rapid deterioration of his symptoms within several months led him to refer to our department for surgery. Within one month the size of tumor increased to involve the T4-6 level, consequently worsening his gait disturbance. He underwent surgery and tumor mass was resected. However, there was leptomeningeal dissemination of the tumor cells on the surface of cord. A near-total resection was therefore achieved. Histopathology revealed the resected specimen had immunoreactivity for EMA/Vimentin/CD56/CD99/S-100/GFAP, with a Ki-67 index of ~35%. These factors led to the diagnosis of anaplastic ependymoma. Seven weeks postoperatively he received adjuvant radiotherapy to the whole brain and the whole spinal cord. He recovered as an independent ambulator without recurrence 1 year postoperatively. Discussion: Because of their rarity, there are no clear treatment or adjuvant therapy guidelines for spinal anaplastic ependymoma. Adjuvant radiotherapy to the whole brain and spinal cord was necessarily indicated after near-total resection. Although the patient’s condition has not recurred 1 year after surgery, careful and serial follow-up is necessary for this individual.

Background: Extreme lateral interbody fusion (XLIF) is often used with posterior spinal fixation (PSF) to treat adult spinal deformity (ASD). However, the amount of intraoperative blood loss (IBL) reported for XLIF may underestimate the total blood loss (TBL). The objective of this study was to determine the total perioperative blood loss in XLIF for ASD. Methods: We assessed 30 consecutive ASD patients with Schwab-SRS type L (mean age: 68.7 ± 8.2 years; mean follow-up 2.0 ± 1.3 years) who were treated by multilevel XLIF (mean, 2.5 ± 0.6 levels) followed by PSF after 3–5 days. We calculated the TBL after XLIF by the Gross equation, by hemoglobin (Hb) balance, and by the Orthopedic Surgery Transfusion Hemoglobin European Overview (OSTHEO) formula. We defined hidden blood loss (HBL) as the difference between the TBL and IBL. Pearson correlation, Spearman correlation, and multiple logistic regression analysis were performed to investigate the risk factors related to HBL. Results: Post-XLIF blood tests showed a significant decrease in the Hb (from 11.8 ± 1.1 mg/dl to 10.6 ± 1.1 mg/dl) and hematocrit (from 36.0 ± 3.2% to 32.5 ± 3.2%). Although the mean IBL was relatively small (33 ± 52 mL), we calculated the TBL as 291 ± 171 mL (Gross equation) and the HBL as 258 ± 168 mL by Gross equation, which was 8 times greater than the IBL on average. There was no difference in the results obtained using the three methods. Multiple logistic regression analysis indicated preoperative lumber lordosis was the risk factor of high HBL (Odds ratio = 1.085, 95%CI: 1.006–1.170, p = 0.035). Conclusions: The HBL in XLIF was 8 times greater than the IBL. During the perioperative course of correction and fusion surgery for ASD with XLIF, surgeons need to pay attention not to underestimate the TBL.

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.

Spondylocostal dysostosis (SCDO) is a heterogeneous group of skeletal disorders characterized by multiple segmentation defects involving vertebrae and ribs. Seven disease genes have been reported as causal genes for SCDO: DLL3, MESP2, TBX6, HES7, RIPPLY2, DMRT2, and LFNG. Here we report a Japanese SCDO case with multiple severe vertebral anomalies from cervical to sacral spine. The patient was a compound heterozygote for c.372delG (p.K124Nfs*) and c.601G>A (p.D201N) variants of LFNG, which encodes a glycosyltransferase (O-fucosylpeptide 3-beta-N-acetylglucosaminyltransferase). The missense variant was in the DxD motif, an active-site motif of the glycosyltransferase, and its loss of the enzyme function was confirmed by an in vitro enzyme assay. This is the second report of LFNG mutations in SCDO.

Study Design: Retrospective cohort study. Objectives: Intraspinal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is often misdiagnosed preoperatively as schwannoma or meningioma because its imaging characteristics are not well understood. As postoperative prognosis differs among the 3 lesions, predicting the probability of SFT/HPC preoperatively is essential. Thus, this study investigates the imaging characteristics of SFT/HPC compared with those of schwannoma or meningioma and evaluates surgical outcomes. Methods: The preoperative imaging findings, tumor resection extent, recurrence and regrowth rates, and neurological improvement were compared between 10 patients with SFT/HPC and 42 patients with schwannoma or 40 patients with meningioma. Results: Most patients with SFT/HPC showed isointensity on both T1- and T2-weighted images compared with patients with schwannoma (P = 0.011 and 0.029, respectively) and no significant difference compared with patients with meningioma (P = 0.575 and 0.845, respectively). Almost all patients with SFT/HPC showed highly uniformizing enhancement patterns, similar to those with meningioma (P = 0.496). Compared with meningioma, SFT/HPC lacked the dural tail sign and intratumoral calcification and exhibited irregular shape. Of the 5 patients who underwent partial resection, 60% exhibited tumor recurrence and regrowth following surgery. Conclusions: Complete en bloc surgical resection should be attempted in patients with intraspinal SFT/HPC to prevent postoperative recurrence or regrowth. As this tumor is often preoperatively misdiagnosed, we recommend that the imaging findings exhibited in this study should be used to positively suspect SFT/HPC. This will enhance patient outcomes by enabling more appropriate preoperative surgical planning.

Ossification of the posterior longitudinal ligament (OPLL) is commonly associated with diabetes mellitus (DM); however, the impact of DM on cervical spine surgery for OPLL remains unclear. This study was performed to evaluate the influence of diabetes DM on the outcomes following cervical spine surgery for OPLL. In total, 478 patients with cervical OPLL who underwent surgical treatment were prospectively recruited from April 2015 to July 2017. Functional measurements were conducted at baseline and at 6 months, 1 year, and 2 years after surgery using JOA and JOACMEQ scores. The incidence of postoperative complications was categorized into early (_30 days) and late (>30 days), depending on the time from surgery. From the initial group of 478 patients, 402 completed the 2-year follow-up and were included in the analysis. Of the 402 patients, 127 (32%) had DM as a comorbid disease. The overall incidence of postoperative complications was significantly higher in patients with DM than in patients without DM in both the early and late postoperative periods. The patients with DM had a significantly lower JOA score and JOACMEQ scores in the domains of lower extremity function and quality of life than those without DM at the 2-year follow-up.

Purpose: Although lung volume (LV) can be measured directly by computed tomography (CT), the literature regarding CT-assessed LV in adolescent idiopathic scoliosis (AIS) patients is limited, and the influence of posterior spinal fusion with instrumentation (PSF) on LV has not been established. This study aimed to identify factors associated with decreased LV after PSF in AIS patients. Methods: We retrospectively reviewed 111 consecutive AIS patients who were between 10 and 20 years of age and were treated by PSF at our facility. We assessed age at surgery, sex, height, body weight, Risser stage, Lenke classification, radiographic parameters, pulmonary function tests, and LV. Factors associated with a postoperative decrease in LV were identified by multivariable analysis. Results: The mean total LV had increased at the 2-year follow-up, although marginally significant (p =.06), and there was a significant increase in the left LV (p =.01) but not the right LV (p =.25). We observed a postoperative reduction in total LV, defined as a total LV postoperative/preoperative ratio < 0.9, in 20 of the 111 patients (18.0%). Univariable analysis showed a significant correlation between ≥ 11 fusion levels and postoperative LV reduction (OR 3.11, 95% CI 1.13–8.57). This factor remained significant in the multivariable analysis, which yielded an adjusted OR of 2.82 (95% CI 1.01–7.93) for postoperative LV reduction in patients with ≥ 11 fusion levels. Conclusion: Our data suggest that a longer fusion area is associated with postoperative LV reduction. Therefore, avoidance of a longer fusion area of ≥ 11 will be preferable for preserving LV. Graphical abstract: These slides can be retrieved under Electronic Supplementary Material.[Figure not available: see fulltext.].

OBJECTIVE Lumbar spinal canal stenosis (LSS) and knee osteoarthritis (KOA), both of which are age-related degenerative diseases, are independently correlated with increased pain and dysfunction of the lower extremities. However, there have been few studies that investigated whether LSS patients with KOA exhibit poor clinical recovery following lumbar spinal surgery. The aim of this study was to elucidate the surgical outcomes of lumbar spinal surgery for LSS patients with KOA using multiple health-related quality of life (HRQOL) parameters. METHODS A total of 865 consecutive patients who underwent posterior lumbar spinal surgery for LSS were retrospectively reviewed. Baseline characteristics, radiographic parameters, perioperative factors, and multiple HRQOL parameters were analyzed preoperatively and at 1-year follow-up. HRQOL items included the Zurich Claudication Questionnaire, Oswestry Disability Index, Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ). The effectiveness of surgical treatment was assessed using the JOABPEQ. The treatment was regarded as effective when it resulted in an increase in postoperative JOABPEQ score by ≥ 20 points compared with preoperative score or achievement of a postoperative score of ≥ 90 points in those with a preoperative score of < 90 points. RESULTS A total of 32 LSS patients with KOA were identified, and 128 age- and sex-matched LSS patients without KOA were selected as controls. In both groups, all HRQOL parameters markedly improved at the 1-year follow-up. On the SF-36, the postoperative mean score for the role physical domain was significantly lower in the KOA group than in the control group (p = 0.034). The treatment was significantly less “effective” in the social life domain of JOABPEQ in the KOA group than in the control group (p < 0.001). CONCLUSIONS The surgical outcomes of LSS patients with KOA are favorable, although poorer than those of LSS patients without KOA, particularly in terms of social life and activities. These results indicate that LSS patients with KOA experience difficulty in routine work or ordinary activities due to knee pain or restricted knee ROM even after lumbar spinal surgery. Hence, preoperative KOA status warrants consideration when planning lumbar spinal surgery and estimating surgical outcomes of LSS.

Study Design:This was a case-control study.Objective:The objective of this study was to clarify the surgical outcomes after cervical posterior decompression in patients who smoked.Summary of Background Data:Smoking is associated with poor outcomes in the field of spinal surgery. However, the impact of tobacco smoking on the outcomes after posterior decompression surgery has not been fully evaluated in patients with cervical spondylotic myelopathy.Materials and Methods:In this retrospective multicenter study, 587 patients with cervical spondylotic myelopathy were enrolled at 17 institutions in Japan. Patients underwent cervical laminoplasty or laminectomy and were followed up for at least 1 year after surgery. Outcome measures were: preoperative smoking status, perioperative complications, the Japanese Orthopedic Association scale, and the Visual Analog Scale for neck pain. After adjusting for age and sex by exact matching, smoking and nonsmoking groups were compared using an unpaired t test for continuous variables or a χ2test for categorical variables.Results:There were 182 (31%) current smokers and 405 (69%) nonsmokers including previous smokers. After matching, 158 patients were extracted from each group. Demographic data and surgical information were almost the same between the groups. Regarding postoperative complications, there was no significant difference in the rate of surgical site infection, cerebrospinal fluid leakage, hematoma, segmental motor paralysis, or neurological deficit. However, smokers showed a significantly higher risk for delirium (3.8% vs. 0.0%, P=0.039). Smokers and nonsmokers showed comparable changes in functional recovery according to Japanese Orthopedic Association scores (3.2±2.1 vs. 3.0±2.1, P=0.425) and in neck pain reduction using the Visual Analog Scale (-1.7±3.1 vs. -1.4±2.8, P=0.417) at the final follow-up.Conclusions:Smokers exhibited functional restoration and neck pain reduction after cervical posterior decompression. Attention is required, however, for the postoperative complication of delirium, which could be caused by the acute cessation of tobacco smoking after admission.Level of Evidence:Level III.