Lower preoperative Hounsfield unit values as a risk factor for poor 5-year clinical outcomes after lumbar spine surgery.

OBJECTIVE: Hounsfield Unit (HU) value has been associated with future osteoporotic fractures and postoperative complications. However, no studies on the impact of low HU values on mid-term clinical outcomes following lumbar spine surgery have been reported. We aimed to evaluate the usefulness of preoperative HU values for 5-year clinical outcomes following lumbar spine surgery. METHODS: We enrolled 200 patients who underwent lumbar surgery (≤ 3-disc levels) for lumbar spinal stenosis. HU values were assessed using preoperative lumbar computed tomography as part of routine preoperative planning for lumbar surgery. Patients were divided into two groups based on the cutoff value of the HU values obtained from the receiver operating characteristic curve for the incidence of vertebral fractures within five years postoperatively. Clinical scores preoperatively and 1, 2, and 5 years postoperatively, including Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and Short Form-36 (SF-36), were compared using a mixed-effects model. RESULTS: Comparative analysis indicated that all domains of JOABPEQ, except for lumbar function, and the physical component summary of the SF-36 were significantly worse in the low HU group than in the high HU group. Using multiple regression analysis, low HU values were significantly correlated with worse 5-year postoperative scores in all domains of JOABPEQ and SF-36. CONCLUSION: Low preoperative HU values are a risk factor for poor 5-year clinical outcomes after lumbar spine surgery. HU values are not only a valuable tool for analyzing bone mineral density but also may be a valuable poor prognostic factor of postoperative clinical outcomes.

Relationship between body mass index and spinal pathology in community-dwelling older adults.

PURPOSE: To clarify the relationship between body mass index (BMI) and spinal pathologies including spinal sagittal balance, back extensor strength (BES), paraspinal muscle mass, prevalent vertebral fracture, disc degeneration, Modic changes, low back pain, and quality of life (QOL) in community-dwelling older adults. METHODS: This study included 380 participants (age: ≥ 65 years, male/female: 152/228) from the Shiraniwa Study. Multivariate nonlinear regression analysis was used to investigate the relationship between BMI and sagittal vertical axis (SVA), BES, paraspinal muscle mass, visual analog scale (VAS) for low back pain, Oswestry Disability Index (ODI), and EuroQoL-5 Dimension (EQ5D) score after adjusting for sex, age, Hospital Anxiety and Depression Scale score, and Charlson Comorbidity Index. In addition, multiple logistic regression analysis was used to investigate the association between BMI and prevalent vertebral fracture, disc degeneration, and Modic changes. RESULTS: BMI was significantly correlated with SVA, BES, paraspinal muscle mass, VAS, ODI, and EQ5D score. The increase in BMI was associated with the deterioration of all outcomes, which accelerated when the BMI increased from approximately 22-23 kg/m2. Moreover, overweight/obesity was significantly correlated with disc degeneration and Modic changes. CONCLUSION: Increased BMI is significantly associated with spinal pathologies such as SVA, BES, paraspinal muscle mass, VAS, QOL, disc degeneration, and Modic changes. The findings suggest that measures for controlling overweight and obesity among older adults can play an important role in the prevention and treatment of spinal pathologies.

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.

Artificial intelligence model to identify elderly patients with locomotive syndrome: A cross-section study.

BACKGROUND: Identifying elderly individuals with locomotive syndrome is important to prevent disability in this population. Although screening tools for locomotive syndrome are available, these require time commitment and are limited by an individual's ability to complete questionnaires independently. To improve on this limitation, we developed a screening tool that uses information on the distribution of pressure on the plantar surface of the foot with an artificial intelligence (AI)-based decision system to identify patients with locomotor syndrome. Herein, we describe our AI-based system and evaluate its performance. METHODS: This was a cross-sectional study of 409 participants (mean age, 73.5 years). A foot scan pressure system was used to record the planter pressure distribution during gait. In the image processing step, we developed a convolutional neural network (CNN) to return the logit of the probability of locomotive syndrome based on foot pressure images. In the logistic regression step of the AI model, we estimated the predictor coefficients, including age, sex, height, weight, and the output of the CNN, based on foot pressure images. RESULTS: The AI model improved the identification of locomotive syndrome among elderly individuals compared to clinical data, with an area under curve of 0.84 (95% confidence interval, 0.79-0.88) for the AI model compared to 0.80 (95% confidence interval, 0.75-0.85) for the clinical model. Including the footprint force distribution image significantly improved the prediction algorithm (the net reclassification improvement was 0.675 [95% confidence interval, 0.45-0.90] P < 0.01; the integrated discrimination improvement was 0.059 [95% confidence interval, 0.039-0.088] P < 0.01). CONCLUSIONS: The AI system, which includes force distribution over the plantar surface of the foot during gait, is an effective tool to screen for locomotive syndrome.

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of lumbar spinal stenosis, 2021 - Secondary publication.

BACKGROUND: The Japanese Orthopaedic Association (JOA) guideline for the management of lumbar spinal stenosis (LSS) was first published in 2011. Since then, the medical care system for LSS has changed and many new articles regarding the epidemiology and diagnostics of LSS, conservative treatments such as new pharmacotherapy and physical therapy, and surgical treatments including minimally invasive surgery have been published. In addition, various issues need to be examined, such as verification of patient-reported outcome measures, and the economic effect of revised medical management of patients with lumbar spinal disorders. Accordingly, in 2019 the JOA clinical guidelines committee decided to update the guideline and consequently established a formulation committee. The purpose of this study was to describe the formulation we implemented for the revision of the guideline, incorporating the recent advances of evidence-based medicine. METHODS: The JOA LSS guideline formulation committee revised the previous guideline based on the method for preparing clinical guidelines in Japan proposed by the Medical Information Network Distribution Service in 2017. Background and clinical questions were determined followed by a literature search related to each question. Appropriate articles based on keywords were selected from all the searched literature. Using prepared structured abstracts, systematic reviews and meta-analyses were performed. The strength of evidence and recommendations for each clinical question was decided by the committee members. RESULTS: Eight background and 15 clinical questions were determined. Answers and explanations were described for the background questions. For each clinical question, the strength of evidence and the recommendation were both decided, and an explanation was provided. CONCLUSIONS: The 2021 clinical practice guideline for the management of LSS was completed according to the latest evidence-based medicine. We expect that this guideline will be useful for all medical providers as an index in daily medical care, as well as for patients with LSS.

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.

The health-related quality of life of patients with musculoskeletal disorders after the COVID-19 pandemic.

PURPOSE: To verify changes in the health-related quality of life (HRQOL) of patients with musculoskeletal disorders after the coronavirus disease 2019 (COVID-19) pandemic and to assess the relationship between the patients' change in several activities of daily living and in the HRQOL to discover factors related to the deterioration in HRQOL. METHODS: A multi-centre cross-sectional questionnaire survey was administered between November 1, 2020, and December 31, 2020, in Japan. The participants included those who visited the orthopaedics clinic within the survey period and had experienced the first and second waves of COVID-19 in Japan and the first stay-at-home order issued by the government. Patients' HRQOL at the two different time points (pre-outbreak and post-second wave of COVID-19) was assessed with the EuroQoL-5 dimensions 5-level (EQ-5D). RESULTS: The survey was completed by 1254 patients (average age: 52.5 ± 21.9 years; 644 women). Among them, 431 patients (34.3%) reported a decrease in the EQ-5D index after the pandemic. The largest decrease was in the pain domain followed by the mobility domain. Multivariate logistic regression analysis revealed that the patients with decreased regular exercise habits were significantly related to deterioration in HRQOL compared with those with stable regular exercise (adjusted odds ratio = 1.76, p < 0.001) independently from age, sex, and change of symptoms. CONCLUSIONS: Up to 35% of patients with musculoskeletal disorders reported deterioration of HRQOL after the COVID-19 pandemic. Pain and mobility rather than anxiety were the two leading factors of the HRQOL decrease. The decrease in regular exercise was related to the HRQOL decrease.

Predictors for quality of life improvement after acute osteoporotic vertebral fracture: results of post hoc analysis of a prospective randomized study.

PURPOSE: No study has investigated the clinical and radiographic risk factors for the deterioration of quality of life (QOL) beyond 6 months after osteoporotic vertebral fractures (OVF). The purpose of this study was to identify the predictors associated with poor QOL improvement after OVF. METHODS: This post hoc analysis included 166 women aged 65-85 years with acute 1-level OVFs. For the patient-reported outcome measures, scores on the European Quality of Life-5 Dimensions (EQ-5D) scale, and visual analogue scale (VAS) for low back pain were used. Lateral radiography at 0, 12, and 48 weeks and magnetic resonance imaging (MRI) at enrollment and at 48 weeks were performed. The associations between baseline variables with change scores for EQ-5D were investigated using a multiple linear regression model. RESULTS: Univariate analysis showed that time since fracture, EQ-5D score, and VAS for low back pain at 0 week showed significant association with increased EQ-5D score from 0 to 48 weeks. According to the multiple regression analysis, the following equation was obtained: increased EQ-5D score from 0 to 48 weeks = 1.305 - 0.978 × EQ-5D at 0 week - 0.021 × VAS for low back pain at 0 week - 0.006 × age + (fluid-intensity T2-weighted MR image patterns: - 0.037, except for fluid-intensity T2-weighted MR image patterns: + 0.037). CONCLUSION: In conclusion, older patients with severe low back pain and fluid-intensity T2-weighted MR image patterns were more likely to have lower QOL improvements after OVFs and may therefore need extra support to improve QOL.

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.

Risk factors for subsequent vertebral fracture after acute osteoporotic vertebral fractures.

PURPOSE: To investigate the incidence and characteristics of subsequent vertebral fracture after osteoporotic vertebral fractures (OVFs) and identify risk factors for subsequent vertebral fractures. METHODS: This post-hoc analysis from a prospective randomized multicenter trial included 225 patients with a 48-week follow-up period. Differences between the subsequent and non-subsequent fracture groups were analyzed. RESULTS: Of the 225 patients, 15 (6.7%) had a subsequent fracture during the 48-week follow-up. The annual incidence of subsequent vertebral fracture after fresh OVFs in women aged 65-85 years was 68.8 per 1000 person-years. Most patients (73.3%) experienced subsequent vertebral fractures within 6 months. At 48 weeks, European Quality of Life-5 Dimensions, the Japanese Orthopedic Association Back Pain Evaluation Questionnaire pain-related disorder, walking ability, social life function, and lumbar function scores were significantly lower, while the visual analog scale (VAS) for low back pain was higher in patients with subsequent fracture. Cox proportional hazards analysis showed that a VAS score ≥ 70 at 0 weeks was an independent predictor of subsequent vertebral fracture. After adjustment for history of previous fracture, there was a ~ 67% reduction in the risk of subsequent vertebral fracture at the rigid-brace treatment. CONCLUSION: Women with a fresh OVF were at higher risk for subsequent vertebral fracture within the next year. Severe low back pain and use of soft braces were associated with higher risk of subsequent vertebral fractures. Therefore, when treating patients after OVFs with these risk factors, more attention may be needed for the occurrence of subsequent vertebral fractures. LEVEL OF EVIDENCE: III.

Predictors of dropout from cohort study due to deterioration in health status, with focus on sarcopenia, locomotive syndrome, and frailty: From the Shiraniwa Elderly Cohort (Shiraniwa) study.

BACKGROUND: Conditions of the elderly like sarcopenia, locomotive syndrome, and frailty have been attracting attention recently. However, the relationship of these 3 conditions and the difference in the magnitude of influence each has on deterioration in health status remain unclear. The purpose of this study was to investigate the prevalence and relationship of sarcopenia, locomotive syndrome, and frailty, and to clarify their influence on the dropout from cohort study due to deterioration in health status. METHODS: The 1st survey of the Shiraniwa Elderly Cohort (Shiraniwa) study was conducted in 2016. We examined 409 participants (aged ≥ 65 years; 164 males, 245 females) and assessed sarcopenia, locomotive syndrome, and frailty. Those who could not attend the 2nd survey (2017) due to deterioration in health status were defined as the Dropout group. We investigated the predictors of Dropout using multiple logistic regression analysis. RESULTS: The prevalence of sarcopenia, locomotive syndrome stage 2, and frailty were 4.4%, 40.1%, and 14.2%, respectively; 89.7% of participants with frailty were also diagnosed with locomotive syndrome stage 2. From the results of the 2nd survey, 46 people were classified into the Dropout group. Independent predictors of the Dropout were locomotive syndrome stage 2 (adjusted odds ratio [OR]: 2.42, 95% confidence interval [CI]: 1.11-5.31) and frailty (adjusted OR: 3.37, 95%CI: 1.56-7.30). CONCLUSIONS: Locomotive syndrome stage 2 was the most common condition in the elderly, and most people with frailty also had locomotive syndrome stage 2. Locomotive syndrome stage 2 and frailty independently influenced the dropout from cohort study due to deterioration in health status. These results suggest that screening for locomotive syndrome is useful for early detection of the elderly with a risk of deterioration in health status, and screening for frailty may contribute to detecting the elderly with higher risk of deterioration in health status.

Predictors of residual low back pain after acute osteoporotic compression fracture.

BACKGROUND: Studies on the clinical and radiographic risk factors for the residual low back pain beyond 6 months after osteoporotic vertebral fractures (OVFs) are lacking. Hence, this study aimed to characterize a patient population with residual low back pain 48 weeks after acute OVFs and to identify the risk factors associated with residual low back pain. METHODS: This prospective multicenter study included 166 female patients aged 65-85 years with acute one-level OVFs. We defined the residual low back pain as visual analog scale (VAS) for low back pain ≥3.5 at 48 weeks in this study, as VAS score ≥3.5 is used to describe moderate or severe pain. Thus, outcome and risk factor analyses were performed by comparing patients with VAS scores <3.5 and ≥ 3.5. In the radiographic analysis, the anterior vertebral body compression percentage was measured at 0, 12, and 48 weeks. Magnetic resonance imaging (MRI) was performed at enrollment and 48 weeks. RESULTS: Of the 166 patients analyzed, 58 complained of residual low back pain at 48 weeks after OVFs. At 0 weeks, the VAS score was significantly higher, and the JOABPEQ mental health score and anterior vertebral body compression percentage were significantly lower in patients with persistent pain 48 weeks after OVFs. The independent risk factors in the acute phase for persistent pain 48 weeks after OVFs were a high VAS score, MRI T2 fluid-intensity image pattern, and a lower anterior vertebral body compression percentage. CONCLUSIONS: Severe low back pain, MRI T2 fluid-intensity image pattern, and severe vertebral body collapse in the acute phase were significant risk factors for residual low back pain 48 weeks after OVFs. Patients with acute OVFs who have these risk factors should be carefully monitored for the possible development of residual chronic low back pain.

Low paravertebral muscle mass in patients with bone metastases from lung cancer is associated with poor prognosis.

PURPOSE: Low skeletal muscle mass has been associated with poor prognosis in patients with advanced lung cancer. However, little is known about the relationship between skeletal muscle mass and overall survival in patients with bone metastases from lung cancer. The objective of the present study was to evaluate the prognostic value of low trunk muscle mass in predicting overall survival in these patients. METHODS: The data from 198 patients who were diagnosed with bone metastases from lung cancer from April 2009 to May 2017 were retrospectively reviewed. The areas of the psoas and paravertebral muscles were measured at the level of the third lumbar vertebra on computed tomography scans taken at the time nearest to the diagnosis of bone metastasis. Muscle area was evaluated for male and female cohorts separately using different cutoff points. Cox proportional hazards analysis was performed to evaluate the factors independently associated with overall survival. RESULTS: The overall survival of patients in the lowest quartile for psoas muscle area or paravertebral muscle area was significantly shorter than that of patients above the 25th percentile for muscle area (p < 0.001). Multivariate analyses showed that paravertebral muscle mass (hazard ratio, 1.73; 95% confidence interval, 1.17-2.56; p = 0.006), epidermal growth factor receptor-targeted therapy, and performance status were independent prognostic factors. CONCLUSIONS: Low paravertebral muscle mass was associated with shorter survival, independently of known prognostic factors.

Prognostic value of paravertebral muscle density in patients with spinal metastases from gastrointestinal cancer.

PURPOSE: Morphometric analyses have shown that trunk muscle mass and density are associated with mortality in cancer patients. Because of the low incidence of spinal metastasis from gastrointestinal cancer and the limited life expectancy of these patients, few studies have been reported in this population. We evaluated the prognostic value of trunk muscle area and density in predicting overall survival. METHODS: The data from 78 patients with spinal metastases from gastrointestinal cancer, collected from February 2009 to July 2016, were evaluated. Psoas muscle and paravertebral muscle area and density were measured at the L3 level on CT scans taken at the time nearest to the diagnosis of spinal metastasis. Cox proportional hazards analysis was performed to evaluate the factors independently associated with overall survival. RESULTS: The mean patient age was 68.3 years (range, 42-88 years). The overall median survival time was 4.8 months: 2.2 months in the extremely rapid growth group (stomach, biliary tract, and pancreas) and 7.6 months in the rapid growth group (esophagus, liver, and colorectum). Multivariate analyses showed that lower paravertebral muscle density (HR 2.23 [95% CI 1.24-3.99], p = 0.007), extremely rapid growth group, presence of abnormal laboratory data, poor performance status, and chemotherapy after spinal metastasis were independent prognostic factors. CONCLUSIONS: Median overall survival was poor among patients with spinal metastases from gastrointestinal carcinoma, especially among those with gastric, biliary tract, or pancreatic cancer. Lower paravertebral muscle density was an independent poor prognostic factor in patients with spinal metastases from gastrointestinal cancer.

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.