Development and validation of a prediction model for falls among older people using community-based data.

This is the first study to employ multilevel modeling analysis to develop a predictive tool for falls in individuals who have participated in community group exercise over a year. The tool may benefit healthcare workers in screening community-dwelling older adults with various levels of risks for falls. PURPOSE: The aim of this study was to develop a calculation tool to predict the risk of falls 1 year in the future and to find the cutoff value for detecting a high risk based on a database of individuals who participated in a community-based group exercise. METHODS: We retrospectively reviewed a total of 7726 physical test and Kihon Checklist data from 2381 participants who participated in community-based physical exercise groups. We performed multilevel logistic regression analysis to estimate the odds ratio of falls for each risk factor and used the variance inflation factor to assess collinearity. We determined a cutoff value that effectively distinguishes individuals who are likely to fall within a year based on both sensitivity and specificity. RESULTS: The final model included variables such as age, sex, weight, balance, standing up from a chair without any aid, history of a fall in the previous year, choking, cognitive status, subjective health, and long-term participation. The sensitivity, specificity, and best cutoff value of our tool were 68.4%, 53.8%, and 22%, respectively. CONCLUSION: Using our tool, an individual's risk of falls over the course of a year could be predicted with acceptable sensitivity and specificity. We recommend a cutoff value of 22% for use in identifying high-risk populations. The tool may benefit healthcare workers in screening community-dwelling older adults with various levels of risk for falls and support physicians in planning preventative and follow-up care.

Periostin increased by mechanical stress upregulates interleukin-6 expression in the ligamentum flavum.

Ligamentum flavum (LF) hypertrophy is a major cause of lumbar spinal canal stenosis. Although mechanical stress is thought to be a major factor involved in LF hypertrophy, the exact mechanism by which it causes hypertrophy has not yet been fully elucidated. Here, changes in gene expression due to long-term mechanical stress were analyzed using RNA-seq in a rabbit LF hypertrophy model. In combination with previously reported analysis results, periostin was identified as a molecule whose expression fluctuates due to mechanical stress. The expression and function of periostin were further investigated using human LF tissues and primary LF cell cultures. Periostin was abundantly expressed in human hypertrophied LF tissues, and periostin gene expression was significantly correlated with LF thickness. In vitro, mechanical stress increased gene expressions of periostin, transforming growth factor-ß1, α-smooth muscle actin, collagen type 1 alpha 1, and interleukin-6 (IL-6) in LF cells. Periostin blockade suppressed the mechanical stress-induced gene expression of IL-6 while periostin treatment increased IL-6 gene expression. Our results suggest that periostin is upregulated by mechanical stress and promotes inflammation by upregulating IL-6 expression, which leads to LF degeneration and hypertrophy. Periostin may be a pivotal molecule for LF hypertrophy and a promising therapeutic target for lumbar spinal stenosis.

Effects of smoking cessation on endothelial function as assessed by flow-mediated total dilation.

BACKGROUND: In assessing the effects of smoking cessation on endothelial function, low-flow-mediated constriction (L-FMC) may provide complementary information to flow-mediated dilation (FMD). However, the value of flow-mediated total dilation (FMTD), an index that incorporates L-FMC into FMD, remains underreported. We aimed to evaluate the effect of smoking cessation on endothelial function, as assessed by FMD and FMTD, and clarify its associated clinical factors. METHODS: We enrolled 118 consecutive current smokers without previous coronary artery disease (72.9% were men; age: 59 ± 11 years) who underwent smoking cessation treatment. The clinical variables %FMD, %L-FMC, and %FMTD were examined before and 20 weeks after treatment initiation. A multivariate linear regression model was used to investigate the effects of smoking cessation on %FMD and %FMTD and the interaction between smoking cessation and baseline clinical variables. RESULTS: After 20 weeks, 85 smokers (69.4% were men; age: 59 ± 12 years) ceased smoking (abstainers), whereas 33 smokers (81.8% were men; age: 58 ± 11 years) did not (continued smokers). The estimated group differences (abstainers - continued smokers) in changes in the %FMD and %FMTD were 0.77% (95% confidence interval [CI], -0.22-1.77%; p = 0.129) and 1.17% (95% CI, 0.16-2.18%; p = 0.024), respectively. Smoking cessation-associated improvement in %FMTD was greater in women than in men (5.41% [95% CI, 3.15-7.67%] versus 0.24% [95% CI, -0.81-1.28%]; p-value for interaction, < 0.001). Additionally, a greater %FMTD improvement was observed in patients who smoked fewer cigarettes per day (p-value for interaction, 0.042) and those who had a smaller resting baseline lumen diameter (Dbase) (p-value for interaction, 0.023). CONCLUSIONS: Smoking cessation was associated with an improvement in %FMTD. Sex, cigarettes smoked per day, and Dbase significantly affected this improvement. The FMTD may help in risk stratification after smoking cessation.

Less-invasive decompression procedures can reduce risk of reoperation for lumbar spinal stenosis with diffuse idiopathic skeletal hyperostosis extended to the lumbar segment: analysis of two retrospective cohorts.

PURPOSE: Clinical outcomes after decompression procedures are reportedly worse for lumbar spinal stenosis (LSS) with diffuse idiopathic skeletal hyperostosis (DISH), especially DISH extended to the lumbar segment (L-DISH). However, no studies have compared the effect of less-invasive surgery versus conventional decompression techniques for LSS with DISH. The purpose of this study was to compare the long-term risk of reoperation after decompression surgery focusing on LSS with L-DISH. METHODS: This study compared open procedure cohort (open conventional fenestration) and less-invasive procedure cohort (bilateral decompression via a unilateral approach) with ≥ 5 years of follow-up. After stratified analysis by L-DISH, patients with L-DISH were propensity score-matched by age and sex. RESULTS: There were 57 patients with L-DISH among 489 patients in the open procedure cohort and 41 patients with L-DISH among 297 patients in the less-invasive procedure cohort. The reoperation rates in L-DISH were higher in the open than less-invasive procedure cohort for overall reoperations (25% and 7%, p = 0.026) and reoperations at index levels (18% and 5%, p = 0.059). Propensity score-matched analysis in L-DISH demonstrated that open procedures were significantly associated with increased overall reoperations (hazard ratio [HR], 6.18; 95% confidence interval [CI], 1.37-27.93) and reoperations at index levels (HR, 4.80; 95% CI, 1.04-22.23); there was no difference in reoperation at other lumbar levels. CONCLUSIONS: Less-invasive procedures had a lower risk of reoperation, especially at index levels for LSS with L-DISH. Preserving midline-lumbar posterior elements could be desirable as a decompression procedure for LSS with L-DISH.

Machine-learning-based approach for nonunion prediction following osteoporotic vertebral fractures.

PURPOSE: An osteoporotic vertebral fracture (OVF) is a common disease that causes disabilities in elderly patients. In particular, patients with nonunion following an OVF often experience severe back pain and require surgical intervention. However, nonunion diagnosis generally takes more than six months. Although several studies have advocated the use of magnetic resonance imaging (MRI) observations as predictive factors, they exhibit insufficient accuracy. The purpose of this study was to create a predictive model for OVF nonunion using machine learning (ML). METHODS: We used datasets from two prospective cohort studies for OVF nonunion prediction based on conservative treatment. Among 573 patients with acute OVFs exceeding 65 years in age enrolled in this study, 505 were analyzed. The demographic data, fracture type, and MRI observations of both studies were analyzed using ML. The ML architecture utilized in this study included a logistic regression model, decision tree, extreme gradient boosting (XGBoost), and random forest (RF). The datasets were processed using Python. RESULTS: The two ML algorithms, XGBoost and RF, exhibited higher area under the receiver operating characteristic curves (AUCs) than the logistic regression and decision tree models (AUC = 0.860 and 0.845 for RF and XGBoost, respectively). The present study found that MRI findings, anterior height ratio, kyphotic angle, BMI, VAS, age, posterior wall injury, fracture level, and smoking habit ranked as important features in the ML algorithms. CONCLUSION: ML-based algorithms might be more effective than conventional methods for nonunion prediction following OVFs.

Incidence of and risk factors for spondylolisthesis, scoliosis, and vertebral fracture in rheumatoid arthritis.

INTRODUCTION: Although lumbar lesions such as spondylolisthesis, scoliosis, and vertebral fracture are not specific to rheumatoid arthritis (RA), the prevalence is high in RA patients. However, no longitudinal study has evaluated lumbar lesions in RA. This study aimed to investigate the incidence of and risk factors for lumbar lesions in RA by a prospective longitudinal cohort study. MATERIALS AND METHODS: The study cohort comprised 110 patients with RA from the 'analysis of factors for RA spinal disorders (AFFORD)' study who completed the secondary survey at a single orthopaedic outpatient RA clinic. Radiological examination included standing radiographs and magnetic resonance imaging (MRI) of the lumbar spine. New development of spondylolisthesis, scoliosis, and vertebral fracture were assessed between baseline and secondary survey. RESULTS: The incidences of spondylolisthesis, scoliosis, and vertebral fracture were 42%, 16%, and 12%, respectively, during a mean follow-up of 7 years. The independent risk factor for de novo scoliosis was poor control of RA (adjusted odds ratio [aOR] 4.81, p = 0.011), while the independent risk factors for new vertebral fracture was use of glucocorticoid at secondary survey (aOR 14.87, p = 0.012). Patients with de novo scoliosis exhibited more severe low back pain and lower quality of life than those without. CONCLUSION: The incidence of scoliosis was related in patients with poor control of RA, while new vertebral fracture was more common in patients with use of glucocorticoid. Control of disease activity might be important in preventing radiological lumbar disorders in RA.

Decreased muscle mass and strength affected spinal sagittal malalignment.

PURPOSE: Correction surgeries for spinal malalignment showed good clinical outcomes; however, there were concerns including increased invasiveness, complications, and impact on medico-economics. Ideally, an early intervention is needed. To better understand the patho-mechanism and natural course of spinal alignment, the effect of factors such as muscle mass and strength on spinal sagittal imbalance were determined in a multicenter cross-sectional study. METHODS: After excluding metal implant recipients, 1823 of 2551 patients (mean age: 69.2 ± 13.8 years; men 768, women 1055) were enrolled. Age, sex, past medical history (Charlson comorbidity index), body mass index (BMI), grip strength (GS), and trunk muscle mass (TM) were reviewed. Spinal sagittal imbalance was determined by the SRS-Schwab classification. Multiple comparison analysis among four groups (Normal, Mild, Moderate, Severe) and multinomial logistic regression analysis were performed. RESULTS: On multiple comparison analysis, with progressing spinal malalignment, age in both sexes tended to be higher; further, TM in women and GS in both sexes tended to be low. On multinomial logistic regression analysis, age and BMI were positively associated with spinal sagittal malalignment in Mild, Moderate, and Severe groups. TM in Moderate and Severe groups and GS in the Moderate group were negatively associated with spinal sagittal malalignment. CONCLUSION: Aging, obesity, low TM, and low GS are potential risk factors for spinal sagittal malalignment. Especially, low TM and low GS are potentially associated with more progressed spinal sagittal malalignment. Thus, early intervention for muscles, such as exercise therapy, is needed, while the spinal sagittal alignment is normal or mildly affected.

Risk factors for low back pain increase in rheumatoid arthritis: Analysis of a 7-year follow-up study.

OBJECTIVE: Several studies have demonstrated that low back pain (LBP) is related to disease activity in patients with rheumatoid arthritis (RA). However, there is no longitudinal research. This study aimed to determine the impacts and risk factors for LBP increase in RA in a longitudinal cohort study. METHODS: The study evaluated 113 patients with RA who completed the secondary survey. LBP increase was defined as ≥1 standard deviation of mean change in visual analogue scale (VAS) between the baseline and secondary surveys. The impacts of LBP increase on quality of life (QOL) and psychological status were evaluated. Risk factors were assessed among patient demographic characteristics and radiological changes. RESULTS: Mean change in VAS for LBP was -0.8 ± 30.4 mm during a mean 7-year follow-up. LBP increase was defined as ≥30-mm increase in VAS for LBP. Patients with LBP increase had significantly lower QOL and worse mental status than patients without it. Poor control of RA was identified as an independent risk factor for LBP increase (odds ratio, 9.82, p = .001). CONCLUSION: Patients with poor control of RA were likely to experience LBP increase in the long term. Control of RA disease activity is important for control of LBP, QOL, and mental status.

Classification and prognostic factors of residual symptoms after minimally invasive lumbar decompression surgery using a cluster analysis: a 5-year follow-up cohort study.

PURPOSE: Residual symptoms indicating incomplete remission of lower leg numbness or low back pain may occur after spine surgery. The purpose was to elucidate the pattern of residual symptoms 5 years after minimally invasive lumbar decompression surgery using a cluster analysis. METHODS: The study comprised 193 patients with lumbar spinal stenosis (LSS) (108 men, 85 women) ranging in age from 40 to 86 years (mean, 67.9 years). Each patient underwent 5-year follow-up. The Japanese Orthopedic Association score and visual analog scale scores for low back pain, leg pain, and leg numbness at 5 years were entered into the cluster analysis to characterize postoperative residual symptoms. Other clinical data were analyzed to detect the factors significantly related to each cluster. RESULTS: The analysis yielded four clusters representing different patterns of residual symptoms. Patients in cluster 1 (57.0%) were substantially improved and had few residual symptoms of LSS. Patients in cluster 2 (11.4%) were poorly improved and had major residual symptoms. Patients in cluster 3 (17.6%) were greatly improved but had mild residual low back pain. Patients in cluster 4 (14.0%) were improved but had severe residual leg numbness. Prognostic factors of cluster 2 were a short maximum walking distance, motor weakness, resting lower leg numbness, cofounding scoliosis, and high sagittal vertical axis. CONCLUSIONS: This is the first study to identify specific patterns of residual symptoms of LSS after decompression surgery. Our results will contribute to acquisition of preoperative informed consent and identification of patients with the best chance of postoperative improvement.

A bone replacement-type calcium phosphate cement that becomes more porous in vivo by incorporating a degradable polymer.

This study investigated whether mixing low viscosity alginic acid with calcium phosphate cement (CPC) causes interconnected porosity in the CPC and enhances bone replacement by improving the biological interactions. Furthermore, we hypothesized that low viscosity alginic acid would shorten the setting time of CPC and improve its strength. CPC samples were prepared with 0, 5, 10, and 20% low viscosity alginic acid. After immersion in acetate buffer, possible porosification in CPC was monitored in vitro using scanning electron microscopy (SEM), and the setting times and compressive strengths were measured. In vivo study was conducted by placing CPC in a hole created on the femur of New Zealand white rabbit. Microcomputed tomography and histological examination were performed 6 weeks after implantation. SEM images confirmed that alginic acid enhanced the porosity of CPC compared to the control, and the setting time and compressive strength also improved. When incorporating a maximum amount of alginic acid, the new bone mass was significantly higher than the control group (P = 0.0153). These biological responses are promising for the translation of these biomaterials and their commercialization for clinic applications.

Long-term participation in community-based group resistance exercises delays the transition from robustness to frailty in older adults: a retrospective cohort study.

BACKGROUND: How community-based group resistance exercises affect the transition from robustness to frailty remains unclear. Thus, we conducted a retrospective cohort study to determine whether the trajectory from robustness to frailty over age differed depending on the duration of participation in group exercises. METHODS: We analyzed the Kihon Checklist (KCL) score of community-dwelling elderly residents of Sumoto city, Hyogo prefecture, who participated in community-based group resistance exercises between April 2010 and December 2019. Finally, 2567 older individuals were analyzed using multilevel modeling. The explanatory variables of interest were the frailty score measured using the KCL for each individual, where 0-3, 4-7, and ≥8 points denoted robustness, pre-frailty, and frailty, respectively. We considered age, sex, systolic blood pressure, pulse, duration of participation, and change in KCL score from baseline as possible confounders. Participants were classified as follows based on the duration of participation in the exercises: <3 times, short-term participation group; 4-6 times; mid-term participation group; and 7-13 times, long-term participation group. The mean duration from the baseline physical test for the total sample was 2.35 years (SD=2.51). RESULTS: The participants' mean total KCL score at baseline was 4.9±3.7. Multilevel modeling analysis revealed that the KCL scores changed by 0.82 points for each additional year of age (p<0.001) and changed by - 0.93 points for long-term participate group (p<0.001). The Estimated Marginal Means (EMM) of the KCL score was 3.98 (95%CI: 3.69, 4.28) points in the short-term participation group and was significantly worse than that of the long-term participation group at 70 years of age (p=0.001). The EMM was 4.49 (95%CI: 4.24, 4.74) at 75 years of age in the mid-term participation group and was significantly worse than that of the long-term participation group. The EMM was 3.87 (95%CI: 3.57, 4.16) in the long-term participation group and significantly better than that of the short-term (p<0.001) and mid-term (p=0.002) participation groups. CONCLUSION: Participation in community-based group resistance exercises prolongs the transition from robustness to frailty. The improved KCL scores at baseline in the long-term participation group remained in the robust range at 75 years of age, which suggests the importance of initiating participation before the onset of functional decline.

Diffuse idiopathic skeletal hyperostosis is associated with lumbar spinal stenosis requiring surgery.

Factors related to the onset and progression of lumbar spinal stenosis (LSS) have not yet been identified. Diffuse idiopathic skeletal hyperostosis (DISH) increases mechanical loading on the non-fused lumbar levels and may therefore lead to LSS. This cross-sectional study aimed to identify associations between LSS and DISH. This study included 2363 consecutive patients undergoing surgery for LSS and 787 general inhabitants without symptoms of LSS as participants of the population-based cohort study, Research on Osteoarthritis/Osteoporosis Against Disability. Standing whole-spine radiographs were used to diagnose DISH based on the criteria proposed by Resnick and Niwayama. The prevalence of DISH showed a significant step-wise increase among asymptomatic inhabitants without radiographic LSS, asymptomatic inhabitants with radiographic LSS, and patients with LSS requiring surgery (14.4, 21.1, and 31.7%, respectively; p < 0.001). The distribution of DISH was similar between the groups, but the lower thoracic and upper-middle lumbar spine regions were more frequently involved in patients with LSS requiring surgery. Multivariate analysis indicated that DISH was an independent associated factor for LSS requiring surgery (adjusted odds ratio 1.65; 95% confidence interval 1.32-2.07) after adjustment for age, sex, body mass index, and diabetes mellitus. Among patients with LSS requiring surgery, a higher occurrence of stenosis at the upper lumbar levels and multi-level stenosis were observed in patients with DISH requiring surgery than in patients without DISH. In conclusion, DISH is independently associated with LSS requiring surgery. The decrease in the lower mobile segments by DISH may increase the onset or severity of LSS.

Sarcopenia is related to spinal sagittal imbalance in patients with spinopelvic mismatch.

PURPOSE: To clarify the relationship between sarcopenia and spinopelvic parameters. METHODS: Among outpatients of spine surgery department, 126 patients (mean age 77.2 years. M/F = 71/55) were included. We diagnosed patients with sarcopenia using the diagnostic algorithm of the Asian Working Group for Sarcopenia. Spinopelvic parameters and the prevalence of spinopelvic mismatch (pelvic incidence minus lumbar lordosis ≥ 10°) were investigated and compared between patients with and without sarcopenia. Furthermore, we compared the spinopelvic parameters between the Sarcopenia and No Sarcopenia groups under each condition of spinopelvic match and mismatch. RESULTS: The prevalence of sarcopenia in this study was 21.4%. Overall, the spinopelvic parameters except thoracic kyphosis (TK) (Sarcopenia: 34.7°, No Sarcopenia: 24.3°, p < 0.01) were not significantly different between the Sarcopenia and No Sarcopenia groups. Prevalence of patients with spinopelvic mismatch was also not significantly different between the Sarcopenia and No Sarcopenia groups (37.0% vs. 42.4%, p = 0.66). Among patients without spinopelvic mismatch, there was no spinopelvic parameter with a significant difference between the 2 groups. However, among patients with spinopelvic mismatch, sagittal vertebral axis (SVA) (115.7 mm vs. 58.7 mm, p < 0.01) and TK (36.6° vs. 21.3°, p < 0.01) of the Sarcopenia group were significantly larger than those of the No Sarcopenia group. Moreover, sarcopenia was independently related to a significant increase in SVA (ß = 50.7, p < 0.01) and TK (ß = 14.0, p < 0.01) in patients with spinopelvic mismatch, after adjustment for age. CONCLUSIONS: Sarcopenia is related to spinal sagittal imbalance because of insufficient compensation by flattening thoracic kyphosis in patients with spinopelvic mismatch. These slides can be retrieved under Electronic Supplementary Material.

The association of back muscle strength and sarcopenia-related parameters in the patients with spinal disorders.

PURPOSE: To evaluate the correlations between back muscle strength, trunk muscle mass, and sarcopenia-related parameters in patients with spinal disorders. METHODS: This cross-sectional observational study included 230 consecutive patients with spinal disorders who visited our outpatient clinic (age range 65-92 years). We measured back muscle strength, handgrip strength, gait speed, and appendicular and trunk skeletal muscle mass using bioimpedance analysis. We classified the subjects into the sarcopenia, dynapenia, or normal stages in accordance with the guidelines set by the European Working Group on Sarcopenia in Older People, and used the cutoff values reported in the guidelines set by the Asian Working Group for Sarcopenia. RESULTS: Back muscle strength was significantly correlated with trunk muscle mass (males: r = 0.47, P < 0.001; females: r = 0.39, P < 0.001), handgrip strength (males: r = 0.67, P < 0.001; females: r = 0.59, P < 0.001), and gait speed (males: r = 0.49, P < 0.001; females: r = 0.51, P < 0.001). The respective incidences of the sarcopenia, dynapenia, and normal stages were 16.4%, 26.7%, and 56.9% for males, and 23.7%, 50.9%, and 25.4% for females. Dynapenia was significantly more prevalent in females than in males. Back muscle strength in the normal group was significantly greater than that in the sarcopenic and dynapenic groups. CONCLUSION: Back muscle strength is significantly correlated with trunk muscle mass and sarcopenia-related parameters in patients with spinal disorders. Back muscle strength in the sarcopenic stage is significantly lesser than that in the normal stage. Although sarcopenia is a multifaceted geriatric syndrome, spinal disorders might be one of the risk factors for disease-related sarcopenia. These slides can be retrieved from Electronic Supplementary Material.

ISSLS PRIZE IN CLINICAL SCIENCE 2019: clinical importance of trunk muscle mass for low back pain, spinal balance, and quality of life-a multicenter cross-sectional study.

STUDY DESIGN: A multicenter cross-sectional study. OBJECTIVES: To clarify the relationship of trunk muscle mass with low back pain, spinal sagittal balance, and quality of life. Few reports have investigated the relationship of trunk muscle mass with lumbar spine function and spinal balance, and the clinical significance of trunk muscle mass remains unclear. METHODS: Patients attending spinal outpatient clinics at 10 different medical institutions were enrolled in this study. Patient demographics, trunk muscle mass and appendicular skeletal muscle mass (ASM) measured by bioelectrical impedance analysis (BIA), body mass index (BMI), Charlson Comorbidity Index (CCI), the Oswestry Disability Index (ODI), visual analog scale (VAS) for low back pain, sagittal vertical axis (SVA), and EuroQol 5 Dimension (EQ5D) score were investigated. Multivariate nonlinear regression analysis was used to investigate the association of trunk muscle mass with the ODI, VAS score, SVA, and EQ5D score. RESULTS: Of 2551 eligible patients, 1738 (mean age 70.2 ± 11.0 years; 781 men and 957 women) were enrolled. Trunk muscle mass was significantly correlated with the ODI, VAS score, SVA, and EQ5D score (P < 0.001) when adjusted for age, sex, BMI, ASM, CCI, and history of lumbar surgery. Patient deterioration was associated with a decrease in trunk muscle mass, and the deterioration accelerated from approximately 23 kg. CONCLUSIONS: Trunk muscle mass was significantly associated with the ODI, VAS score, SVA, and EQ5D score. Trunk muscle mass may assume an important role to elucidate and treat lumbar spinal dysfunction and spinal imbalance. These slides can be retrieved under Electronic Supplementary Material.

Anatomical analysis of the human ligamentum flavum in the thoracic spine: Clinical implications for posterior thoracic spinal surgery.

BACKGROUND: Knowledge of the ligamentum flavum anatomy is important for posterior spinal surgery. However, only a few studies have evaluated the relationship between the thoracic ligamentum flavum and its surrounding structures. This study aimed to clarify the anatomy of the thoracic ligamentum flavum. METHODS: The entire spines from 20 human embalmed cadavers were harvested in an en bloc fashion. All pedicles were vertically cut using a thread bone saw, and the ligamentum flavum from T1-T2 to T12-L1 was painted using a contrast agent containing an iron powder. Computed tomography was performed, and the ligamentum flavum shape (width and height) and its relationship with the spinal bony structures (lamina and foramen height percentage covered by the ligamentum flavum) were analyzed using a three-dimensional analyzing software. RESULTS: The thoracic ligamentum flavum height and width gradually increased from T1-T2 to T12-L1. The caudal lamina height ventrally covered by the ligamentum flavum also increased gradually from the upper (T1-T2: 31.7%) to the lower levels (T12-L1: 41.7%); however, the cranial lamina height dorsally covered by the ligamentum flavum decreased from the upper (12.6%) to the lower levels (4.3%). The neural foramen was covered by the ligamentum flavum in all thoracic spines, except for T1-T2. Between T2-T3 and T12-L1, approximately 50% of the cranial part of the foramens was covered by the ligamentum flavum; however, the caudal part was not covered. CONCLUSIONS: This study using contrasted ligamentum flavum and reconstructed CT provided information on the thoracic ligamentum flavum shape and its relationship with the bony structures. The ventral ligamentum flavum coverage of the cranial lamina increase from cranial to caudal, and the cranial half of the neural foramen is covered by the ligamentum flavum below T2-T3 but not in T1-T2. These findings would help spine surgeons to design and perform safe and adequate posterior thoracic spinal surgeries.

The degeneration of adjacent intervertebral discs negatively influence union rate of osteoporotic vertebral fracture: A multicenter cohort study.

BACKGROUND: With the increasing aging population in developed countries, there has been an associated increased prevalence of osteoporotic vertebral fracture (OVF). Many previous reports have attempted to predict the risk of delayed union associated with OVF. However, the role of endplate failure and the degeneration of adjacent intervertebral discs, and their association with delayed union has received little attention. The aim of this study was to evaluate the endplate fracture and disc degeneration rank as risk factors for delayed union. MATERIALS AND METHODS: Two hundred and eighteen consecutive patients with fresh OVF were enrolled in the study. MRI and X-ray were performed at the time of enrollment and at the 6 months follow-up. The MR images were used to assess the degeneration grade of adjacent intervertebral discs (using the modified Pfirrmann grading system), and endplate failure. Supine and weight-bearing radiographs were used to define angular motion and compression ratio of the anterior vertebral body wall. RESULTS: A total of 139 patients (112 female, 27 male) completed the 6 month follow-up (a 65.1% follow-up rate). The study revealed 27 cases of delayed union (19.4%). A healthier adjacent caudal disc with low grade degeneration was found to be associated with an increased risk of delayed union (P = 0.008). Bi-endplate injury and significant compression of the anterior vertebral body wall were significantly associated with delayed union (P = 0.019, and P = 0.001 respectively). Rapid progression of the adjacent cranial disc degeneration was observed at the end of the 6 month follow-up period (P = 0.001). CONCLUSION: Modified Pfirrmann grading system revealed that a healthier adjacent intervertebral disc at the caudal level and bi-endplate fracture were significantly associated with an increased risk of delayed union. These findings may influence the management strategy for patients with OVF.

Differences in short-term clinical and radiological outcomes depending on timing of balloon kyphoplasty for painful osteoporotic vertebral fracture.

BACKGROUND: Balloon kyphoplasty or vertebroplasty is widely performed as a surgical intervention for osteoporotic vertebral fracture (OVF) and the effects have been investigated in many previous studies. However, the influence of the timing of the procedure on patient outcomes has not been studied formally. The purpose of this study was to investigate differences in the surgical outcomes of OVFs according to the timing of balloon kyphoplasty. METHODS: This was a multicenter cohort study. Participants comprised 72 consecutive patients who underwent balloon kyphoplasty between January 2012 and January 2016. Patients were analyzed in two groups according to the timing of kyphoplasty after onset (Early group: ≤2 months; Late group: >2 months). Follow-up continued for more than 6 months. RESULTS: A total of 72 patients were effectively analyzed. Of these, 27 (38%) patients underwent kyphoplasty within 2 months after symptom onset. The Late group showed greater angular motion of fractured vertebrae (p = 0.005) and compression of anterior vertebral height (p = 0.001) before surgery. Final outcomes adjusted for age and preoperative outcome showed lower visual analog scale (VAS) scores for low back pain in the Early group than in the Late group (19.9 vs. 30.4, p = 0.049). Final relative anterior vertebral height and kyphotic angle were more preserved in the Early group than in the Late group (p = 0.002 and p = 0.020, respectively), although absolute differences were not significant. CONCLUSIONS: Vertebral height and kyphotic angle before and after balloon kyphoplasty were greater in patients who underwent kyphoplasty within 2 months after onset, and the VAS score for low back pain at final follow-up was better. Our results support kyphoplasty within 2 months.

Anatomical analysis of human ligamentum flavum in the cervical spine: Special consideration to the attachments, coverage, and lateral extent.

BACKGROUND: Posterior decompression surgeries of cervical spine such as laminoplasty and laminoforaminotomy are well established and increasing in aging population. The anatomical knowledge of cervical ligamentum flavum (LF) is critical to perform posterior spinal surgeries, however, few studies have evaluated it, especially the relation of LF and neural foramen. METHODS: The whole spine was removed en bloc from 15 formalin-embalmed human cadavers and then divided into two segments along the pedicle bases. A total of 90 LFs from C2-C3 to C7-T1 were measured manually from the ventral side before being painted with iron powder containing contrast agent and scanned by computed tomography. We recorded dimensions, coverage of adjacent laminae, and the relationships between LF and neural foramen or facet joints. Three-dimensional CT data was used to evaluate manually limited areas and make reconstructed images. RESULTS: LF height gradually increased from C2-C3 to C7-T1, and gradually decreased from medial to lateral within each level. LF width and thickness were relatively constant from cranial to caudal. The laminar surface covered by LF gradually increased from 33% in para midline and 30% laterally at C2, and increased to 70% in para midline and 47% laterally at C6, this trend was not completed at C7. The empty zone of the laminar surface (without LF coverage) was located at the upper half of each lamina; this zone gradually decreased from cranial to caudal. The craniomedial side of the cervical facet joint was covered by a mean 4.6 ± 0.7 mm of LF, however, LF did not enter the cervical neural foramen. CONCLUSIONS: LF did not enter the neural foramen in cervical spine unlike lumbar spine. This information might be critical to avoid neurological deterioration after cervical laminoplasty or laminoforaminotomy. Surgeons would imagine the attachments and coverage of LF and its relation to posterior bony structures to perform safe posterior cervical surgeries.

Anatomical analysis of the relation between human ligamentum flavum and posterior spinal bony prominence.

BACKGROUND: Posterior spinal bony prominences are commonly used as landmarks during posterior spinal surgery; however, the exact relationship of these structures with ligamentum flavum (LF) borders and attachments has not been clarified. MATERIALS AND METHODS: Whole spines were removed en bloc from 20 embalmed human cadavers. Plain radiographs and computed tomography (CT) scans of each whole spine were taken, and then the spine was divided in two parts along the pedicle bases. The LFs were painted with contrast dye, and second radiographs and CT scans were taken again. Radiographic data were analyzed using CT image analyzer. RESULTS: The craniolateral border of LF at four upper lumbar levels (from L1/2 to L4/5) located cranial to isthmus in both sides (3.5 mm), meanwhile, it located at or below isthmus in both sides at L5-S1 level (0.5 mm). In the midline, LF attached below the isthmus levels at four upper lumbar levels (4 mm), though it located in the same level of isthmus at L5-S1 (1 mm). The mean distance between medial border of pedicles and lateral border of LF increased from upper to the lower lumbar levels (6.5 mm at L1/2 - 11.4 mm at L5-S1). Distance between interlaminar space and cranial border of LF at the midline gradually increased from 8.2 mm at L1 toward 11.1 mm at L4, it was 9.3 mm in L5. CONCLUSIONS: From the data of new analytical method using contrasted LF and reconstructed CT, the detailed relations between bony prominence and the border of LF were uncovered. Based on these findings and reconstructed LF images superimposed on lamina, surgeons would design safe and adequate lumbar spinal decompression with imagination of overall pictures of the LF from the dorsal side.