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Aims: The escalating demand for medical resources to address spinal diseases as society ages is an issue that requires careful evaluation. However, few studies have examined trends in spinal surgery, especially unscheduled hospitalizations or surgeries performed after hours, through large databases. Our study aimed to determine national trends in the number of spine surgeries in Japan. We also aimed to identify trends in after-hours surgeries and unscheduled hospitalizations and their impact on complications and costs. Methods: We retrospectively investigated data extracted from the Diagnosis Procedure Combination database, a representative inpatient database in Japan. The data from April 2010 to March 2020 were used for this study. We included all patients who had undergone any combination of laminectomy, laminoplasty, discectomy, and/or spinal arthrodesis. Results: This investigation included 739,474 spinal surgeries and 739,215 hospitalizations in Japan. There was an average annual increase of 4.6% in the number of spinal surgeries. Scheduled hospitalizations increased by 3.7% per year while unscheduled hospitalizations increased by 11.8% per year. In-hours surgeries increased by 4.5% per year while after-hours surgeries increased by 9.9% per year. Complication rates and costs increased for both after-hours surgery and unscheduled hospitalizations, in comparison to their respective counterparts of in-hours surgery and scheduled hospitalizations. Conclusion: This study provides important insights for those interested in improving spine care in an ageing society. The swift surge in after-hours spinal surgeries and unscheduled hospitalizations highlights that the medical needs of an increasing number of patients due to an ageing society are outpacing the capacity of existing medical resources. Cite this article: Bone Jt Open 2024;5(8):662–670.

Abstract Background Although posterior decompression with fusion (PDF) are effective for treating thoracic myelopathy, surgical treatment has a high risk of various complications. There is currently no information available on the perioperative complications in thoracic ossification of the longitudinal ligament (T-OPLL) and thoracic ossification of the ligamentum flavum (T-OLF). We evaluate the perioperative complication rate and cost between T-OPLL and T-OLF for patients underwent PDF. Methods Patients undergoing PDF for T-OPLL and T-OLF from 2012 to 2018 were detected in Japanese nationwide inpatient database. One-to-one propensity score matching between T-OPLL and T-OLF was performed based on patient characteristics and preoperative comorbidities. We examined systemic and local complication rate, reoperation rate, length of hospital stays, costs, discharge destination, and mortality after matching. Results In a total of 2,660 patients, 828 pairs of T-OPLL and T-OLF patients were included after matching. The incidence of systemic complications did not differ significantly between the T-OPLL and OLF groups. However, local complications were more frequently occurred in T-OPLL than in T-OLF groups (11.4% vs. 7.7% P = 0.012). Transfusion rates was also significantly higher in the T-OPLL group (14.1% vs. 9.4%, P = 0.003). T-OPLL group had longer hospital stay (42.2 days vs. 36.2 days, P = 0.004) and higher medical costs (USD 32,805 vs. USD 25,134, P

ABSTRACT: Background: Treatment for pyogenic spondylitis tends to be prolonged; however, few studies have examined the factors associated with the time required for infection control. Therefore, we analyzed a consecutive cohort of patients to identify factors associated with the time required to control infection in pyogenic spondylitis. This study aimed to clarify the factors linked to the duration necessary for achieving infection control in cases of pyogenic spondylitis, using C-reactive protein (CRP) normalization as an indicator. Methods: In this retrospective observational study, we investigated 108 patients diagnosed with pyogenic spondylitis. We evaluated the number of days from the first visit to CRP normalization; for cases wherein CRP did not normalize, the number of days to the date of final blood sampling was evaluated. In the present study, infection control in pyogenic spondylitis was defined as a CRP falling within the normal range (≤0.14 mg/dL). We performed univariate and multivariate Cox regression analyses to identify various factors associated with the time required for CRP normalization in pyogenic spondylitis. Results: The mean time required for CRP normalization was 148 days. Univariate Cox regression analysis showed that the serum creatinine level, estimated glomerular filtration rate (eGFR), lymphocyte percentage, neutrophil percentage, CRP level, CRP-albumin ratio, and neutrophil-to-lymphocyte ratio were significantly associated with the time required to control infection. Multivariate Cox regression analysis showed that a higher neutrophil percentage, diabetes mellitus, and a lower eGFR were the independent factors associated with a longer infection control time. Conclusions: We found that a higher neutrophil percentage, diabetes mellitus, and a lower eGFR were significantly associated with a longer time for CRP normalization in pyogenic spondylitis. These findings may help identify patients with pyogenic spondylitis who are at a high risk for an extended infection control period.

Osteoporotic vertebral fractures (OVFs) can hinder physical motor function, daily activities, and the quality of life in elderly patients when treated conservatively. Vertebral augmentation, which includes vertebroplasty and balloon kyphoplasty, is a commonly used procedure for OVFs. However, there have been reports of complications. Although serious complications are rare, there have been instances of adjacent vertebral fractures, cement dislocation, and insufficient pain relief due to cement failure, sometimes necessitating revision surgery. This narrative review discusses the common risks associated with vertebral augmentation for OVFs, such as cement leakage and adjacent vertebral fractures, and highlights the risk of revision surgery. The pooled incidence of revision surgery was 0.04 (0.02–0.06). The risks for revision are reported as follows: female sex, advanced age, diabetes mellitus, cerebrovascular disease, dementia, blindness or low vision, hypertension, hyperlipidemia, split type fracture, large angular motion, and large endplate deficit. Various treatment strategies exist for OVFs, but they remain a subject of controversy. Current literature underscores the lack of substantial evidence to guide treatment strategies based on the risks of vertebral augmentation. In cases with a high risk of failure, other surgeries and conservative treatments should also be considered as treatment options.

ABSTRACT: Background: Due to its association with bone metabolic status and muscle strength/mass, vitamin D deficiency has the potential to affect neurological symptom recovery after surgery for degenerative cervical myelopathy (DCM). However, few studies have investigated the effects of vitamin D deficiency (serum 25(OH)D

Ossification of the posterior longitudinal ligament of the spine (OPLL) is an intractable disease leading to severe neurological deficits. Its etiology and pathogenesis are primarily unknown. The relationship between OPLL and comorbidities, especially type 2 diabetes (T2D) and high body mass index (BMI), has been the focus of attention; however, no trait has been proven to have a causal relationship. We conducted a meta-analysis of genome-wide association studies (GWASs) using 22,016 Japanese individuals and identified 14 significant loci, 8 of which were previously unreported. We then conducted a gene-based association analysis and a transcriptome-wide Mendelian randomization approach and identified three candidate genes for each. Partitioning heritability enrichment analyses observed significant enrichment of the polygenic signals in the active enhancers of the connective/bone cell group, especially H3K27ac in chondrogenic differentiation cells, as well as the immune/hematopoietic cell group. Single-cell RNA sequencing of Achilles tendon cells from a mouse Achilles tendon ossification model confirmed the expression of genes in GWAS and post-GWAS analyses in mesenchymal and immune cells. Genetic correlations with 96 complex traits showed positive correlations with T2D and BMI and a negative correlation with cerebral aneurysm. Mendelian randomization analysis demonstrated a significant causal effect of increased BMI and high bone mineral density on OPLL. We evaluated the clinical images in detail and classified OPLL into cervical, thoracic, and the other types. GWAS subanalyses identified subtype-specific signals. A polygenic risk score for BMI demonstrated that the effect of BMI was particularly strong in thoracic OPLL. Our study provides genetic insight into the etiology and pathogenesis of OPLL and is expected to serve as a basis for future treatment development.

Introduction: In Japan, cervical total disc replacement (TDR) was approved in 2017. However, because of its short history, no comparative study between cervical TDR and anterior cervical discectomy with fusion (ACDF) has been conducted in the country. Therefore, we examined and compared the surgical outcomes of TDR and ACDF for one-level cervical degenerative diseases. Methods: In total, 50 patients who had received anterior surgeries for one-level cervical degenerative diseases were investigated. Among them, 25 underwent TDR (Prestige LP; Medtronic), whereas the other 25 patients underwent ACDF. ACDF samples were selected from cases conducted before the approval of TDR (−2017.9) and were retrospectively judged to be indicated for TDR. Before and at 1 year after surgery, clinical and radiological outcomes were evaluated. Results: No significant differences in terms of patient demographics between the two groups were observed. A longer operative time was observed in the TDR group than in the ACDF group. Postoperatively, no differences in the Japanese Orthopaedic Association score for cervical myelopathy (C-JOA) score, neck pain visual analog scale, C2-7 angle, and C2-7 range of motion (ROM) were determined. TDR tended to show better neck disability index (NDI) scores postoperatively when compared with ACDF. The local angle at operative level was larger in ACDF. In TDR, the local ROMs were maintained postoperatively; however, in ACDF, the local ROM at the operative level was decreased, and the local ROMs at adjacent levels were increased postoperatively. In the TDR group, although heterotopic ossification was observed in 11 patients (44.0%), and anterior bone loss was identified in 14 patients (56.0%), these issues did not affect surgical outcomes. Conclusions: Conclusively, no differences in terms of C-JOA score and neck pain between patients treated through TDR and ACDF were observed. However, a trend of better NDI scores was identified with TDR. While TDR maintained postoperative ROMs, ACDF showed an increase in the local ROMs at adjacent levels.

Introduction: Chemonucleolysis with condoliase (chondroitin sulfate ABC endolyase) has been used to treat patients with lumbar disc herniation (LDH) in Japan since 2018. In this study, we retrospectively investigated clinical outcomes in patients who received an intradiscal condoliase injection for LDH and sought to identify significant predictors of good outcome. Methods: Indications for treatment were as follows: (1) unilateral leg pain with or without back pain, (2) nerve root compression caused by LDH confirmed on magnetic resonance imaging (MRI), and (3) leg pain resistant to at least 1 month of conservative treatment, including medication, nerve root block, or physical therapy. Patients with motor weakness or a history of severe allergy were excluded, as were those with the foraminal or sequestrated type of LDH. The injection was defined as effective if the numeric rating scale score for leg pain improved by 50% at 6 months post-treatment. Results: A total of 52 patients (mean age, 45.0 years) were enrolled and classified according to whether the injection was effective (E group, n=40, 76.9%) or less effective (L group, n=9, 17.3%). Three patients (5.8%) underwent herniotomy for residual pain within 6 months of the injection. There were no severe adverse events. Reduction of herniation was seen on MRI more often in the E group than in the L group. The effectiveness in patients with transligamentous LDH was similar to that in patients with subligamentous LDH. High-intensity signal change in the area of LDH on pretreatment T2-weighted MRI was a significant predictor of successful leg pain relief. Conclusions: An intradiscal condoliase injection was a safe and effective treatment for painful radiculopathy caused by LDH. Leg pain was more likely to improve in patients with high-intensity signal change in the area of LDH before treatment.

Introduction: Breast cancer is one of the most frequent primary tumors that cause spinal metastases. Metastasis consequences impair both the patient's overall prognosis and quality of life. We previously developed a porous hydroxyapatite collagen composite (HAp/Col) as an osteoconductive scaffold. HAp/Col is a commercially available artificial bone that is frequently utilized in spinal fusion. Because of its high absorbance capacity, HAp/Col is regarded as a good chemical carrier. Methods: This study investigated the effect of local administration of paclitaxel combined with HAp/Col scaffold on breast cancer metastasis. High-performance liquid chromatography was used to assess the in vitro release of paclitaxel from HAp/Col. In an in vivo rat model, the inhibitory effects of paclitaxel-impregnated scaffolds on local osteogenesis was examined, and then the local suppression effects on metastatic cancer were investigated. Results: In vitro testing revealed that roughly 30% of the paclitaxel was released within 96 hours. Paclitaxel-impregnated HAp/Col inhibited local osteogenesis for the first 8 weeks in a rat femur. However, at 12 weeks following surgery, this negative effect appeared to have subsided. In the metastatic model, all rats in the control group reached the humane endpoint 14 days after surgery. On the other hand, the average time to the endpoint in the paclitaxel group was 26.5 days, which was substantially longer than that in the control group. Long-term survivors treated with paclitaxel had no remaining tumor cells in the femoral bone, and osteogenesis was seen surrounding the HAp/Col. Conclusions: Paclitaxel-impregnated HAp/Col reduced local tumor development and extended the time to the target endpoint in rats with metastases from breast cancer. This study shows that local implantation of paclitaxel-impregnated HAp/Col may be a viable therapeutic option for the management of breast cancer metastases.

Abstract Background Autologous bone has been used for posterior lumbar intervertebral fusion (PLIF). However, harvesting autologous bone graft is associated with donor site complications. We previously developed a hydroxyapatite/collagen (HAp/Col) composite as an osteoconductive artificial bone, characterized by having a highly porous structure with sponge‐like elasticity. This study aims to investigate the effectiveness of HAp/Col composite with bone marrow aspirate (BMA) as a graft substitute in PLIF for the treatment of lumbar spinal diseases. Methods This study prospectively investigated patients who received one-level PLIF. For the interbody fusion, two titanium cages were inserted. On the one side of interbody space, HAp/Col composite incorporated with BMA filling the titanium cage was grafted. On the other side, local bone graft (LBG) harvested during decompressive laminotomy was grafted and then one-level instrumentation using pedicle screws was performed. The target levels were at L2/3 in 2 cases, L3/4 in 3 cases, L4/5 in 36 cases, and L5/S in 5 cases. We evaluated clinical symptoms and radiological outcomes of 46 patients and compared the fusion status of HAp/Col composite with that of LBG. Results The 1-year postoperative CT evaluation demonstrated that, in the HAp/Col, a complete fusion was observed in 38 patients (82.6%), whereas in the LBG, a complete fusion was observed in 35 patients (76.1%). There were no statistical differences between the HAp/Col and LBG. In the HAp/Col, incomplete fusion was observed in five patients (10.9%) and non-fusion in two patients (4.3%), and in the LBG, incomplete fusion was observed in nine patients (19.6%) and non-fusion in two patients (4.3%). At 2 years after the surgery, complete fusion increased to 44 patients (95.7%) in the HAp/Col and 41 patients (89.1%) in the LBG. There were no significant differences in the clinical scores for lumbar spine between patients with fusion and non-fusion. Conclusions The HAp/Col composite with BMA in the titanium cage can be effectively used as an alternative to conventional autologous LBG for intervertebral spinal fusion. Trial registration University hospital Medical Information Network, UMIN000045010, July 30th, 2021, Retrospectively registered, https://www.umin.ac.jp/english/ .

Objectives: As romosozumab has both bone anabolic and antiresorptive effects, it is not clear which patient groups are more likely to have decreased calcium concentrations when treated with romosozumab. The aim of this study was to investigate the impact of romosozumab treatment on serum calcium concentration in patients with osteoporosis with a high risk of fractures and identify factors that might be associated with, or even predict, a fluctuation in calcium concentration upon romosozumab administration. Materials and methods: In total, 47 patients were included in this retrospective study. We performed a Wilcoxon signed-rank test to identify differences in the calcium concentration before and 1 month after romosozumab initiation. Associations between baseline variables and changes in serum calcium concentration were investigated with a multiple-linear regression model using a forward-backward stepwise procedure. Results: Romosozumab administration reduced the serum calcium concentration by an average of 3.1 % after 1 month. No patient complained of symptoms of hypocalcemia during the first month after treatment. Univariate regression analysis showed that age and calcium concentration were significantly associated with the decrease in serum calcium concentrations by romosozumab administration. In addition, stepwise regression analysis identified age and calcium concentrations as independent factors associated with the decrease in calcium concentration by romosozumab. Conclusion: Romosozumab administration caused a modest but significant decrease in serum calcium concentration. Older age and higher baseline calcium concentrations were associated with a greater decrease in calcium concentrations by romosozumab administration. Although the likelihood of severe hypocalcemia from romosozumab administration may be low, physicians prescribing romosozumab to patients with osteoporosis should be aware of the symptoms of hypocalcemia and promptly evaluate calcium levels if patients complain of these symptoms.

Abstract Background Patients with prolonged and intense neutrophilia after spinal surgery are at high risk of developing surgical site infection (SSI). To date, there is no standard method for the objective assessment of the intensity and duration of neutrophilia. Thus, this retrospective observational study aimed to test a new index (I-index), developed by combining the duration and intensity of neutrophilia, as a predictor of SSI. Methods I-index was calculated based on the postoperative neutrophil percentage. A total of 17 patients with SSI were enrolled as cases, and 51 patients without SSI were selected as controls. The groups were matched at a ratio of 1:3 by age, sex, and surgery type. The differences in the I-index were compared between the groups. Moreover, we checked the cumulative I-index (c-I-index), which we defined as the area under the neutrophil curve from postoperative day 1 until the first clinical manifestation of SSI in each case. Furthermore, a cutoff for SSI was defined using the receiver operating characteristic curve. Results The median I-index-7, I-index-14, and c-I-index were significantly higher in the SSI group than those in the control group. For a cutoff point of 42.1 of the I-index-7, the sensitivity and specificity were 0.706 and 0.882, respectively. For a cutoff point of 45.95 of the I-index-14, the sensitivity and specificity were 0.824 and 0.804, respectively. For a cutoff point of 45.95 of the c-I-index, the sensitivity and specificity were 0.824 and 0.804, respectively. Conclusion We devised a new indicator of infection, i.e., the I-Index and c-I-index, and confirmed its usefulness in predicting SSI.

Superficial siderosis (SS) of the central nervous system is a rare disease caused by chronic and repeated hemorrhages in the subarachnoid space. Recently, attention has been paid on the association of SS and dural defect with ventral fluid-filled collection in the spinal canal (VFCC). The pathophysiology of hemosiderin deposition in patients with SS and dural defects is still unclear. However, previous studies have suggested the possible mechanism: cerebrospinal fluid (CSF) leaks into the epidural space through the ventral dural defect, and repetitive bleeding occurs from the epidural vessels that circulate back to the subarachnoid space through the dural defect, leading to hemosiderin deposition on the surface of the brain, the central nerves, and the spinal cord. Previously, the surgical closure of dural defect via the posterior approach has been reported to be effective in arresting the continued subarachnoid bleeding and disease progression. Herein, we describe SS cases whose dural defects were repaired via the anterior approach. From the direct anterior approach to the ventral dural defect findings, we confirmed that the outer fibrous dura layer is intact, and the defect is localized in the inner thin layer. From the findings of this study, our proposed theory is that dural tear at the inner dural layer causes “dural dissection,” which is likely to occur between the outer fibrous layer and inner dural border cellular layer. Bleeding from the vessels between the inner and outer Line 39–40 dural layers seems to be the pathology of SS with dural defect.

ABSTRACT Excluding clinical trials, there is limited evidence on the effect of 12 months of romosozumab treatment on bone mineral density (BMD) increase in real‐world clinical practice because its use has only been approved recently. Thus, this study aimed to investigate the real‐world effect of 12 months of romosozumab treatment on BMD increase and identify factors that predict the rate of BMD increase after 12 months of romosozumab treatment. We retrospectively investigated 106 patients who completed a 12‐month romosozumab treatment for osteoporosis with a high risk of fractures at four hospitals from March 2020 to March 2022. The univariate and multiple regression analyses were performed to analyze the concurrent effects of various factors on the BMD increase after the 12‐month romosozumab treatment. After 1 year of treatment, the lumbar spine BMD increased by 14.6%, and femoral neck BMD increased by 5.1%. Univariate regression analysis found that male sex, high tartrate‐resistant acid phosphatase 5b (TRACP‐5b) value before romosozumab administration, absence of osteoporosis medications before romosozumab administration, and low baseline lumbar spine BMD were associated with the extent of lumbar spine BMD increase. Moreover, stepwise multiple regression analysis found that the TRACP‐5b value before romosozumab administration was a significant predictor of the rate of lumbar spine BMD increase after 1 year of romosozumab administration. In conclusion, our results demonstrated the effectiveness of the 12‐month romosozumab treatment for osteoporosis with a high risk of fractures and the TRACP‐5b value before romosozumab administration was a significant predictor of the rate of lumbar spine BMD increase after 1 year of romosozumab administration. Our findings could help establish more efficient treatment strategies for patients with osteoporosis at a high risk of fracture. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Abstract Background Degenerative cervical myelopathy (DCM) can significantly impair a patient’s quality of life (QOL). In this study, we aimed to identify predictors associated with QOL improvement after surgery for DCM. Methods This study included 148 patients who underwent surgery for DCM. The European QOL-5 Dimension (EQ-5D) score, the Japanese Orthopedic Association for the assessment of cervical myelopathy (C-JOA) score, and the Nurick grade were used as outcome measures. Radiographic examinations were performed at enrollment. The associations of baseline variables with changes in EQ-5D scores from preoperative to 1-year postoperative assessment were investigated using a multivariable linear regression model. Results The EQ-5D and C-JOA scores and the Nurick grade improved after surgery (P

Abstract Background Parkinson’s disease (PD) has been found to increase the risk of postoperative complications in patients with adult spinal deformity (ASD). However, few studies have investigated this by directly comparing patients with PD and those without PD. Methods In this multicenter retrospective cohort study, we reviewed all surgically treated ASD patients with at least 2 years of follow-up. Among them, 27 had PD (PD+ group). Clinical data were collected on early and late postoperative complications as well as any revision surgery. Radiographic parameters were evaluated before and immediately after surgery and at final follow-up, including sagittal vertical axis (SVA), thoracic kyphosis, lumbar lordosis, sacral slope, and pelvic tilt. We compared the surgical outcomes and radiographic parameters of PD patients with those of non-PD patients. Results For early complications, the PD+ group demonstrated a higher rate of delirium than the PD− group. In terms of late complications, the rate of non-union was significantly higher in the PD+ group. Rates of rod failure and revision surgery due to mechanical complications also tended to be higher, but not significantly, in the PD+ group (p = 0.17, p = 0.13, respectively). SVA at final follow-up and loss of correction in SVA were significantly higher in the PD+ group. Conclusion Extra attention should be paid to perioperative complications, especially delirium, in PD patients undergoing surgery for ASD. Furthermore, loss of correction and rate of non-union were greater in these patients.

Purpose Although the understanding of the mechanisms of low back pain due to spinopelvic sagittal imbalance has strengthened, the understanding of the mechanisms of neck pain remains insufficient. Thus, this study aimed to identify the factors associated with preoperative and postoperative neck pain in patients with degenerative cervical myelopathy who underwent laminoplasty. Methods In this prospective multicenter study, we prospectively enrolled patients who were scheduled for laminoplasty for degenerative cervical myelopathy. The associations between different variables and the Numerical Pain Rating Scale (NRS) scores for neck pain were investigated using univariate and multiple linear regression models. Results In total, 92 patients were included in the current study. The univariate analysis showed that age, sex, cervical lordosis in neutral and extension, and thoracic kyphosis were significantly associated with the preoperative NRS score for neck pain; moreover, preoperative cervical lordosis in extension and range of motion and postoperative cervical lordosis in neutral, flexion, and extension were significantly associated with the postoperative NRS Scale score for neck pain. Stepwise multiple regression analysis showed that the independent factors contributing to preoperative neck pain were preoperative cervical lordosis in extension, sex, and age. The independent preoperative predictor and contributor to postoperative neck pain were preoperative cervical lordosis in extension and postoperative cervical lordosis in extension, respectively. Conclusions Cervical lordosis in extension showed significant association with neck pain in patients with degenerative cervical myelopathy. Therefore, when performing laminoplasty for patients with a low cervical lordosis in extension, attention should be paid to residual postoperative neck pain.

Abstract Background Anterior decompression with fusion (ADF) has often been performed for degenerative cervical myelopathy (DCM) in patients with poor cervical spine alignment and/or anterior cord compression. We aimed to identify clinical and radiological predictors associated with neurological recovery after ADF. Methods This post-hoc analysis from a prospective multicenter study included patients who were scheduled for ADF for DCM. The patients who received other surgeries (laminoplasty, posterior decompression and fusion) were excluded. The associations between baseline clinical and radiographic variables (age, sex, body mass index, etiology, cervical lordosis, range of motion, C7 slope, C2-7 sagittal vertical axis [SVA], thoracic kyphosis [TK], lumbar lordosis, sacral slope, SVA, pelvic tilt, T1 pelvic angle [TPA], the Japanese Orthopedic Association score for the assessment of cervical myelopathy [C-JOA], European Quality of Life Five Dimensions Scale [EQ-5D], Neck Disability Index [NDI], Physical Component Summary of the SF-36 [PCS], and Mental Component Summary of the SF-36) and the recovery rates as the outcome variables were investigated in the univariate regression analysis. Then, the independent predictors for increased recovery rates were evaluated using a stepwise multiple regression analysis. Results In total, 37 patients completed the 1 year follow-up. The recovery rate was significantly correlated with SVA (p = 0.001) and TPA (p = 0.03). Univariate regression analyses showed that age (Regression coefficient = − 0.92, p = 0.049), SVA (Regression coefficient = − 0.57, p = 0.004) and PCS (Regression coefficient = 0.80, p = 0.03) score were significantly associated with recovery rate. Then, a stepwise multiple regression analysis identified the independent predictors of recovery rate after ADF as TK (p = 0.01), PCS (p = 0.03), and SVA (p = 0.03). According to this prediction model, the following equation was obtained: recovery rate = − 8.26 + 1.17 × (TK) − 0.45 × (SVA) + 0.85 × (PCS) (p = 0.002, R 2 = 0.44). Conclusion Patients with lower TK, lower PCS score, and higher SVA were more likely to have poor neurological recovery after ADF. Therefore, patients with DCM and these predictors who undergo ADF should be warned about poor recovery and be required to provide adequate informed consent.

Abstract Background No studies to date have elucidated the clinical factors associated with pedicle screw pull-out during or immediately after surgery. The aim of this study was to assess the frequency of pedicle screw pull-out by comparing intraoperative scans obtained using cone-beam computed tomography (CBCT) with postoperative scans obtained using computed tomography (CT). We also sought to determine the incidence of pedicle screw pull-out and identify relevant risk factors. Methods This was a retrospective analysis of prospectively collected data for 742 pedicle screws placed in 76 consecutive patients who underwent at least triple-level posterior fixation for thoracic or lumbar spinal injury, spinal metastasis, or pyogenic spondylitis between April 2014 and July 2020. Pedicle screw pull-out distance in the axial and sagittal planes was compared between CT scans obtained 2 days postoperatively and CBCT images acquired intraoperatively. Risk factors associated with pedicle screw pull-out were investigated by multivariate logistic regression analysis. Results Pedicle screw pull-out was seen with 58 pedicle screws (7.8%) in 26 patients (34.2%). There were significant differences in age, number of fused segments, frequency of diffuse idiopathic skeletal hyperostosis (DISH), and medical history of osteoporosis for pedicle screw pull-out. Risk factors for pedicle screw pull-out were older age (odds ratio 1.07, 95% confidence interval 1.02–1.130) and a diagnosis of DISH (odds ratio 3.35, 95% confidence interval 1.12–10.00). Several cases suggest that use of connecting rods was an important factor in intraoperative pedicle screw pull-out. Conclusions Our findings suggest that age, number of fused segments, presence of DISH, and medical history of osteoporosis are risk factors for pedicle screw pull-out, with the greatest being older age and DISH.

Abstract Background The surgical treatment of osteoporotic vertebral fractures (OVF) is generally associated with a high risk of complications due to an aging population with osteoporosis; however, the detailed risk factors for systemic complications and mortality have not been clarified. We evaluated the risk factors for systemic complications and mortality in surgically treated OVF patients using a large national inpatient database. Methods Patients over 65 years old who were diagnosed with OVF and received either anterior fusion (AF) or posterior fusion (PF), from 2012 to 2016, were extracted from the diagnosis procedure combination (DPC) database. In each of the perioperative systemic complications (+) or (−) group, and the in-hospital death (+) or (−) group, we surveyed the various risk factors related to perioperative systemic complications and in-hospital death. Results The significant factors associated with systemic complications were older age (OR 1.38, 95% CI 1.09–1.74), a lower activity of daily living score upon admission (OR 1.52, 95%CI 1.19–1.94), atrial fibrillation (OR 2.14, 95%CI 1.25–3.65), renal failure (OR 2.29, 95%CI 1.25–4.20), and surgical procedure (AF, OR 1.73, 95%CI 1.35–2.22). The significant explanatory variables for in-hospital death were revealed to be male sex (OR 3.26, 95%CI 1.20–8.87), a lower body mass index (OR 3.97, 95%CI 1.23–12.86), unscheduled admission (OR 3.52, 95%CI 1.17–10.63), atrial fibrillation (OR 8.31, 95%CI 2.25–30.70), renal failure (OR 7.15, 95%CI 1.32-38.77), and schizophrenia (OR 8.23, 95%CI 1.66–42.02). Conclusions Atrial fibrillation and renal failure as preoperative comorbidities were common factors between perioperative systemic complications and mortality in elderly patients for OVF.

Introduction: Anterior decompression and fusion have shown favorable neurologic outcomes in patients with cervical myelopathy. However, implant migration sometimes occurs immediately after multilevel anterior cervical corpectomy with fusion (ACCF). Risk factors associated with early bone graft migration have not been precisely documented. The study aimed to investigate how frequently bone graft subsidence occurs after ACCF and to determine the factors affecting implant migration. Methods: Forty-seven consecutive patients who underwent ACCF for ossification of the posterior longitudinal ligament at our hospital between 2007 and 2015 and were able to complete 1 year of follow-up were enrolled. Patients treated with hybrid fixation were excluded. Data on demographics and radiographic findings, namely, fused segment angle and fused segment height (FSH), were collected. Implant migration was defined as subsidence of >3 mm. The patients were divided into 2-segment (2F), 3-segment (3F), and 4-segment (4F) groups. Results were compared between the groups using one-way analysis of variance, the Mann-Whitney U test, and the chi-square test. Results: Mean age was 61.6 years in the 2F group (n = 17), 62.1 years in the 3F group (n = 21), and 69 years in the 4F group (n = 9). There were no significant between-group differences in demographics or clinical characteristics. Implant subsidence occurred in 3 cases (17.6%) in the 2F group, 4 (19%) in the 3F group, and 3 (33.3%) in the 4F group. Revision surgery was required in 2 cases (1 patient each in the 3F and 4F groups). Logistic regression analysis showed a significant association of increased FSH and increased risk of postoperative implant subsidence. Conclusions: A postoperative increase in FSH may affect graft stability and lead to early implant migration.

Introduction: The aims of this study were to investigate how adjacent segment degeneration (ASD) occurs at the proximal and distal segments after L3-L5 fusion surgery, namely, floating fusion, and to identify the risk factors for ASD in patients who undergo this surgery. Methods: Fifty patients who underwent floating fusion surgery at vertebrae L3-L5 and developed ASD were enrolled. The following parameters were evaluated: body mass index (BMI), diabetes status, dialysis status, lumbar lordosis, segmental lordosis between the L2 upper endplate and the L3 lower endplate, disc height, Cobb's angle, apical vertebral rotation using the Nash and Moe classification method, preoperative disc degeneration, surgical procedures, and the upper instrumented vertebra (UIV) tilt angle. The UIV tilt angle was defined as positive when the anterior side was directed caudally. Results: Twenty-two (44%) of the 50 patients showed cephalad radiographic ASD (RASD) and 5 patients (10%) showed caudad RASD. Clinically symptomatic ASD was found at L2-L3 in 4 patients (8%) and at L5-S1 in 2 patients (4%). All the patients with clinically symptomatic cephalad ASD underwent revision procedures for radiculopathy or claudication because of degenerative pathology at L3-L4. Multivariate regression analysis showed a significant association of the absolute value of UIV tilt angle (mean |UIV tilt|) with cephalad RASD (odds ratio 1.09, p = 0.038). Receiver-operating characteristic curve analysis showed a significant association of |UIV tilt| >10.3° with RASD (sensitivity 67.9%, specificity 77.3%, area under the curve [AUC] 0.675). Conclusions: RASD was more likely to occur at the adjacent segment on the cephalad side than at the adjacent segment on the caudad side after two-segment floating fusion of L3-L5. A preoperative UIV tilt angle >10° or UIV tilt < −10° was a risk factor for RASD.

Abstract Background Atlantoaxial subluxation (AAS) is characterized by excessive movement at the junction between the atlas (C1) and axis (C2) as a result of either a bony or ligamentous abnormality. Surgical intervention is a therapeutic choice for AAS. In addition to C1 laminectomy (LAM), surgical fixation for subluxation or instability is performed by various techniques. While surgical treatment options for AAS have increased, the outcomes of different surgical techniques remain unclear. Methods The authors conducted a retrospective analysis of the outcomes of 30 consecutive spinal surgeries performed for AAS patients, C1 LAM in 11 cases and C1/2 fixation in 19 cases. We investigated the correlation between the clinical outcomes and the surgical methods. We also examined the factors related to poor outcomes (the recovery rate of the Japanese Orthopedic Association score for cervical myelopathy

Introduction: We describe 5 patients who underwent operative treatment for arachnoid web (AW) and discuss the postoperative clinical outcome in each case. AW is an extremely rare disease that causes cord compression and syringomyelia in the thoracic spine. To date, 14 cases only of AW have been reported, and the effect of surgical intervention on clinical and radiologic outcomes is unknown. Methods: Five patients who underwent surgical treatment for AW were retrospectively reviewed. The clinical outcomes were evaluated using the thoracic Japanese Orthopaedic Association (T-JOA) score. Preoperative and postoperative images were reviewed. Results: All the patients presented with spastic gait and numbness in the lower extremities. Two patients also presented with bladder-bowel dysfunction (BBD). AW, or the so-called “scalpel” sign, was seen dorsally in the thoracic spine on magnetic resonance imaging in all the patients. Syringomyelia adjacent to the web was observed in 4 patients. Fenestration and web resection without instrumentation was performed in all the cases. Overall, significant improvement was seen in locomotion and the total T-JOA score postoperatively. However, numbness in the lower extremities improved in 2 patients but was unchanged in 3 cases. BBD was ameliorated in 1 patient but remained unchanged in the other patient. Conclusions: Our experience suggests that surgical treatment, including the another patient and resection of the web, can correct the flow dynamics of cerebrospinal fluid and allow neurologic recovery, in particular locomotion, in patients with AW.

For ossification of the posterior longitudinal ligament (OPLL) and cervical spondylotic myelopathy (CSM), anterior decompression with fusion (ADF) can accurately achieve spinal decompression. However, the difference in perioperative complications in ADF between OPLL and CSM is poorly described. This study aimed to investigate the perioperative complication rates of patients with degenerative cervical myelopathy undergoing ADF, represented by OPLL and CSM, using a large national inpatient database. In the OPLL and CSM groups, postoperative complication (systemic and local) rates, reoperation rates, medical costs during hospitalization, and mortality after propensity score matching were compared. After matching, 1197 matched pairs were made. The incidence of total systemic complications was similar between both groups (OPLL, 12.4%; CSM, 12.2%). In the OPLL group, more perioperative local complications (cerebrospinal fluid leakage: CSFL, [OPLL, 2.7%; CSM, 0.3%] and surgical site infection: SSI [OPLL, 2.1%; CSM, 0.9%]) were detected, and the hospitalization cost was approximately $3200 higher than that in the CSM group. Moreover, medical costs were significantly higher in patients who experienced complications in both OPLL and CSM. The frequency of perioperative complications of OPLL and CSM in ADF was detailed using large real-world data. Compared to CSM, OPLL had more perioperative complications such as CSFL and SSI, and higher medical costs. Regardless of the disease, medical costs were significantly increased when perioperative complications occurred.

Background: The purpose of this study was to clarify the clinical features of ossification of the posterior longitudinal ligament (OPLL) and extreme ossification at multiple sites. Methods: This prospective study involved patients with a diagnosis of cervical OPLL at 16 institutions in Japan. Patient-reported outcome measures, including responses on the Japanese Orthopaedic Association (JOA) Cervical Myelopathy Evaluation Questionnaire (JOA-CMEQ), JOA Back Pain Evaluation Questionnaire (JOA-BPEQ), and visual analog scale pain score, were collected to investigate clinical status. In each patient, the sum of the levels at which OPLL was located (OP index) was evaluated on whole-spine computed tomography, along with ossification of other spinal ligaments including the anterior longitudinal ligament (OALL), ligament flavum (OLF), supra- and intraspinous ligaments (SSL), and diffuse idiopathic skeletal hyperostosis (DISH). The distribution of OP index values in the study population was investigated, and the clinical and radiologic characteristics of patients in the top 10% were assessed. Results: In total, 236 patients (163 male, 73 female; mean age 63.5 years) were enrolled. Twenty-five patients with OP index ≥ 17 were categorized into a high OP index group and the remainder into a moderate/low OP index group. There were significantly more women in the high OP index group. Patients in the high OP index group also had significantly poorer scores for lower extremity function and quality of life on the JOA-CMEQ and in each domain but not for body pain on the JOA-BPEQ compared with those in the moderate/low OP index group. Patients in the high OP index group had more OALL in the cervical spine and more OLF and SSL in the thoracic spine. The prevalence of DISH was also significantly higher in the high OP index group. In the high OP index group, interestingly, OPLL was likely to be present adjacent to DISH in the cervicothoracic and thoracolumbar spine, especially in men, and often coexisted with DISH in the thoracic spine in women. Conclusion: This prospective cohort registry study is the first to demonstrate the clinical and radiologic features of patients with OPLL and a high OP index. In this study, patients with a high OP index had poorer physical function in the lumbar spine and lower extremities and were also predisposed to extreme ossification of spinal ligaments other than the OPLL.

Objective The increasing number of spinal surgeries being performed in the elderly has increased the incidence of postoperative delirium. The prediction of delirium is complex, and few studies have been performed to examine the preoperative risk factors for delirium after spinal surgery in the elderly. This study was performed to clarify such risk factors in patients aged ≥75 years undergoing spinal surgery. Method This retrospective observational study included 299 patients aged ≥75 years. Comorbidities, medication history, preoperative examination findings, surgery-related characteristics, and health scale assessments, including the 36-Item Short-Form Survey (SF-36) score and prognostic nutritional index (PNI), were examined as potential risk factors for delirium. Results Delirium occurred in 53 patients (17.7%). The preoperative risk factors for delirium were a history of stroke and mental disorders, hypnotic drug use, malnutrition, hyponatremia, anemia, respiratory dysfunction, and cervical surgery. Logistic regression analysis demonstrated that the independent predictors of delirium were a history of stroke, non-benzodiazepine hypnotic drug use, preoperative hyponatremia, the PNI, and the SF-36 physical component summary (PCS) score. Conclusions Independent preoperative predictors of delirium in elderly patients undergoing spinal surgery included a history of stroke, non-benzodiazepine hypnotic drug use, preoperative hyponatremia, the PNI, and the SF-36 PCS score.

Satellite cell proliferation is an essential step in proper skeletal muscle development and muscle regeneration. However, the mechanisms regulating satellite cell proliferation are relatively unknown compared to the knowledge associated with the differentiation of satellite cells. Moreover, it is still unclear whether overload muscle fiber hypertrophy is dependent on satellite cell proliferation. In general, cell proliferation is regulated by the activity of cell cycle regulators, such as cyclins and cyclin-dependent kinases (CDKs). Despite recent reports on the function of CDKs and CDK inhibitors in satellite cells, the physiological role of Cdk1 in satellite cell proliferation remains unknown. Herein, we demonstrate that Cdk1 regulates satellite cell proliferation, muscle regeneration, and muscle fiber hypertrophy. Cdk1 is highly expressed in myoblasts and is downregulated upon myoblast differentiation. Inhibition of CDK1 activity inhibits myoblast proliferation. Deletion of Cdk1 in satellite cells leads to inhibition of muscle recovery after muscle injury due to reduced satellite cell proliferation in vivo. Finally, we provide direct evidence that Cdk1 expression in satellite cells is essential for overload muscle fiber hypertrophy in vivo. Collectively, our results demonstrate that Cdk1 is essential for myoblast proliferation, muscle regeneration, and muscle fiber hypertrophy. These findings could help to develop treatments for refractory muscle injuries and muscle atrophy, such as sarcopenia.

Although osteoporotic vertebral fractures (OVFs) are the most common type of osteoporotic fracture, few reports have investigated the factors contributing to residual low back pain in the chronic phase after OVFs by using radiographic evaluation. We examined the contribution of nonunion, vertebral deformity, and thoracolumbar alignment to the severity of residual low back pain post-OVF. This post hoc analysis of a prospective randomized study included 195 patients with a 48-week follow-up period. We investigated the associations between radiographic variables with the visual analog scale (VAS) scores for low back pain at 48 weeks post-OVF using a multiple linear regression model. Univariate analysis revealed that analgesic use, the local angle on magnetic resonance imaging, anterior vertebral body compression percentage on X-ray, and nonunion showed a significant association with VAS scores for low back pain. Multiple regression analysis produced the following equation: VAS for low back pain at 48 weeks = 15.49 + 0.29 × VAS for low back pain at 0 weeks + (with analgesics: +8.84, without analgesics: −8.84) + (union: −5.72, nonunion: −5.72). Among local alignment, thoracolumbar alignment, and nonunion, nonunion independently contributed to residual low back pain at 48 weeks post-OVF. A treatment strategy that reduces the occurrence of nonunion is desirable.

Purpose: Although the neutrophil–lymphocyte ratio (NLR) is a simple biomarker for inflammation, its diagnostic value for predicting surgical site infection (SSI) after spinal decompression surgery has not been extensively investigated. We aimed to determine the predictive value of NLR for SSI in patients undergoing spinal decompression surgery. Methods: We performed a retrospective observational study of patients who underwent spinal decompression surgery. Consecutive 254 patients were divided into an SSI group and a non-SSI group based on the presence of SSI. We evaluated which markers, including NLR, differed significantly between groups. We then determined the diagnostic cutoff values of these markers for the prediction of SSI based on the significance in the univariate analysis. Results: The incidence of SSI was 7 of 254 patients (2.8%). Univariate analysis showed that there were significant differences in the C-reactive protein (CRP) level at 1 day postoperatively; neutrophil and lymphocyte percentage and NLR at 3–4 days postoperatively; and CRP level, white blood cell count, neutrophil count and percentage, lymphocyte percentage, and NLR at 6–7 days postoperatively between SSI and non-SSI groups. Among these markers, the cutoff values of lymphocyte percentage and NLR at 3–4 days postoperatively for the prediction of SSI were ≤15.1% and ≥4.91, respectively. The cutoff values of lymphocyte percentage and NLR at 6–7 days postoperatively were ≤19.8% and ≥3.21, respectively. Conclusions: Lymphocyte percentage and NLR at 3–4 and 6–7 days postoperatively were useful markers for the early prediction of SSI in patients who had undergone spinal decompression surgery. These parameters may aid in identifying patients at higher risk of SSI after spinal decompression surgery.

Introduction: Patients treated with revision surgery after lumbar decompression with fusion typically have persistent low back pain and lower extremity numbness compared with patients treated with only primary surgery. No well-designed study has investigated the persistence and degree of pain after revision surgery following instrumented operation. The purpose of this study is to compare residual pain among patients who underwent reoperation and those who underwent only primary surgery for lumbar degenerative disorder using patient-based evaluation. Methods: We reviewed 350 consecutive patients (143 men, 207 women, mean age 63 years) treated with primary lumbar instrumented surgery between October 2010 and February 2014 at our institution and followed up for 2 years postoperatively. Patients were categorized into three groups based on number of levels fused: 1-segment, 2-segment, and 3-segment fusion (1F, 2F, and 3F groups, respectively). We used the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and visual analog scales (VASs) for low back pain and lower extremity pain to evaluate pain intensity pre- and postoperatively. Results: Salvage surgery for late-phase complications was required in 5 cases (2.4%), 6 cases (11.3%), and 11 cases (12.1%) in the 1F, 2F, and 3F groups, respectively. In the 1F and 2F groups, patients treated with revision surgery had unsatisfactory improvement in the pain domain of JOABPEQ and VASs for low back pain and lower extremity pain compared with patients with only primary short fusion surgery. The 3F group showed no significant differences between patients who underwent reoperation and those who underwent only primary surgery. Conclusion: Low back pain and lower extremity pain often persist after revision surgery in patients treated with short fusion (2-segment) operation. We need to follow pain states in such patients.

Objectives: As the population ages, the number of lumbar spinal surgeries performed on sarcopenic patients will increase. The purpose of this study was to investigate the prevalence of sarcopenia and evaluated its impact on the results of lumbar spinal surgery. Methods: This study included 2 groups: One group consisted of patients who underwent whole-body dual-energy X-ray absorptiometry (DXA) scanning before the option of undergoing surgery for lumbar spinal disease (LSD group) and a second group consisted of patients underwent DXA scanning for osteoporosis screening under hospital watch at the geriatric medicine department (control group). In order to evaluate the impact of sarcopenia on the clinical outcome of lumbar spinal surgery, the Japanese Orthopedic Association (JOA) score, the recovery rate based on the JOA score, and visual analogue scale (VAS) scores for lower back pain, lower extremity pain, and lower extremity numbness were compared within the LSD group. Results: The prevalence of sarcopenia showed no statistical difference between groups (control group, 50.7%; LSD group, 46.5%). In the LSD group, while the changes in VAS scores showed no statistical difference between the nonsarcopenia subgroup and sarcopenia subgroup, the sarcopenia subgroup demonstrated inferior JOA scores and recovery rates at the final follow-up when compared with the nonsarcopenia subgroup (P

Abstract Background Concurrent cervical and lumbar spinal canal stenosis is known as tandem spinal stenosis (TSS). As research on TSS is limited, there is no consensus on the optimal surgical approach to this problem. We evaluated the prevalence and clinical characteristics of TSS in patients with symptomatic lumbar spinal canal stenosis (LCS). Methods The authors performed a retrospective analysis of the outcomes of 565 patients who underwent lumbar surgeries performed for symptomatic LCS. In all the patients, both the cervical and lumbar regions were evaluated preoperatively, and we compared TSS patients and non-TSS patients in terms of multiple clinical parameters. In the TSS patients, we investigated the ratio and clinical outcomes of additional cervical surgeries performed on TSS patients. Results Two hundred two cases (35.8%) were considered to be TSS. Twenty-eight patients (5.0%) underwent a cervical operation during the follow-up period. There were no differences between the radiographic TSS patients and non-TSS patients in terms of preoperative lumbar-Japanese Orthopedic Association (L-JOA) scores, postoperative L-JOA scores, and the L-JOA recovery rate (14.8 ± 4.4 points vs 14.2 ± 4.6 points, 23.9 ± 4.3 points vs 23.1 ± 4.5 points, 63.7 ± 28.2% vs 60.3 ± 27.9%, respectively), while the TSS group included a greater number of hypertension cases. The recovery rate L-JOA scores of patients who underwent additional cervical surgeries were significantly lower compared with the rate of patients who experienced treatment for only lumbar lesions (62.8 ± 25.8% vs 39.8 ± 35.5%, p = 0.0003). However, additional cervical surgery still improved both the cervical myelopathy-Japanese Orthopedic Association (C-JOA) and L-JOA scores in TSS patients with symptomatic cervical lesion (from 10.3 ± 2.8 points to 12.1 ± 3.0 points, p = 0.0302; from 14.8 ± 7.3 points to 19.9 ± 5.0 points, p = 0.0331, respectively). In these patients, there were no significant differences in the recovery rate of both C-JOA and L-JOA scores between the single-stage surgery group and the staged surgery group (40.7 ± 35.8% vs 20.7 ± 16.1%; 50.9 ± 25.1% vs 34.2 ± 39.3%, respectively). Conclusions Radiographic co-existing cervical stenosis did not affect surgical outcomes for LCS, although symptomatic cervical lesion affected neurological score after lumbar surgery. An additional surgery for cervical lesion significantly improved neurological findings in TSS patients.

To date, it is still unclear how fresh osteoporotic vertebral fractures (OVFs) affect the patient’s quality of life and low back pain during a follow-up period of more than 1 year. In the previous trial, women with fresh OVF were randomized to rigid or soft brace for 12 weeks, then both groups were followed for the subsequent 48 weeks. In women completing this trial at our affiliated hospitals, we conducted a follow-up study to investigate the long-term course of an acute vertebral fracture in terms of pain and quality of life. When comparing visual analog scale scores for low back pain and European Quality of Life-5 Dimensions Questionnaire scores between consecutive time points, a significant difference was found between 0 and 12 weeks, but not between 12 and 48 weeks or between 48 weeks and final follow-up. A total 25% had residual low back pain at the final follow-up. A stepwise logistic regression analysis identified age and previous vertebral fracture as predictors of residual low back pain at the final follow-up. Therefore, the degree of low back pain and impairment of the quality of life improved by 12 weeks after injury and did not change thereafter until a mean follow-up of 5.3 years.

Various studies have found a high incidence of early graft dislodgement after multilevel corpectomy. Although a hybrid fusion technique was developed to resolve implant failure, the hybrid and conventional techniques have not been clearly compared in terms of perioperative complications in patients with severe ossification of the posterior longitudinal ligament (OPLL) involving three or more levels. The purpose of this study was to compare clinical and radiologic outcomes between anterior cervical corpectomy with fusion (ACCF) and anterior hybrid fusion for the treatment of multilevel cervical OPLL. We therefore retrospectively reviewed the clinical and radiologic data of 53 consecutive patients who underwent anterior fusion to treat cervical OPLL: 30 underwent ACCF and 23 underwent anterior hybrid fusion. All patients completed 2 years of follow-ups. Implant migration was defined as subsidence > 3 mm. There were no significant differences in demographics or clinical characteristics between the ACCF and hybrid groups. Early implant failure occurred significantly more frequently in the ACCF group (5 cases, 16.7%) compared with the hybrid group (0 cases, 0%). The fusion rate was 80% in the ACCF group and 100% in the hybrid group. Although both procedures can achieve satisfactory neurologic outcomes for multilevel OPLL patients, hybrid fusion likely provides better biomechanical stability than the conventional ACCF technique.

Background: Although diffuse idiopathic skeletal hyperostosis (DISH) is known to coexist with the ossification of spinal ligaments (OSLs), details of the radiographic relationship remain unclear. Methods: We prospectively collected data of 239 patients with symptomatic cervical ossification of the posterior longitudinal ligament (OPLL) and analyzed the DISH severity on whole-spine computed tomography images, using the following grades: grade 0, no DISH; grade 1, DISH at T3–T10; grade 2, DISH at both T3–T10 and C6–T2 and/or T11–L2; and grade 3, DISH beyond C5 and/or L3. Ossification indices were calculated as the sum of vertebral and intervertebral levels with OSL for each patient. Results: DISH was found in 107 patients (44.8%), 65 (60.7%) of whom had grade 2 DISH. We found significant associations of DISH grade with the indices for cervical OPLL (r = 0.45, p < 0.0001), thoracic ossification of the ligamentum flavum (OLF; r = 0.41, p < 0.0001) and thoracic ossification of the supra/interspinous ligaments (OSIL; r = 0.53, p < 0.0001). DISH grade was also correlated with the index for each OSL in the whole spine (OPLL: r = 0.29, p < 0.0001; OLF: r = 0.40, p < 0.0001; OSIL: r = 0.50, p < 0.0001). Conclusion: The DISH grade correlated with the indices of OSL at each high-prevalence level as well as the whole spine.

Lateral lumbar interbody fusion (LLIF) is increasingly performed as corrective surgery for patients with adult spinal deformity (ASD). This paper compares the surgical results of LLIF and conventional posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) in ASD using a propensity score matching analysis. We retrospectively reviewed patients with ASD who received LLIF and PLIF/TLIF, and investigated patients’ backgrounds, radiographic parameters, and complications. The propensity scores were calculated from patients’ characteristics, including radiographic parameters and preoperative comorbidities, and one–to-one matching was performed. Propensity score matching produced 21 matched pairs of patients who underwent LLIF and PLIF/TLIF. All radiographic parameters significantly improved in both groups at the final follow-up compared with those of the preoperative period. The comparison between both groups demonstrated no significant difference in terms of postoperative pelvic tilt, lumbar lordosis (LL), or pelvic incidence–LL at the final follow-up. However, the sagittal vertical axis tended to be smaller in the LLIF at the final follow-up. Overall, perioperative and late complications were comparable in both procedures. However, LLIF procedures demonstrated significantly less intraoperative blood loss and a smaller incidence of postoperative epidural hematoma compared with PLIF/TLIF procedures in patients with ASD.

Background: This study investigated how diffuse idiopathic skeletal hyperostosis (DISH) influences clinical characteristics in patients with cervical ossification of the posterior longitudinal ligament (OPLL). Although DISH is considered unlikely to promote neurologic dysfunction, this relationship remains unclear. Methods: Patient data were prospectively collected from 16 Japanese institutions. In total, 239 patients with cervical OPLL were enrolled who had whole-spine computed tomography images available. The primary outcomes were visual analog scale pain scores and the results of other self-reported clinical questionnaires. Correlations were sought between clinical symptoms and DISH using the following grading system: 1, DISH at T3-T10; 2, DISH at both T3–10 and C6–T2 and/or T11–L2; and 3, DISH beyond the C5 and/or L3 levels. Results: DISH was absent in 132 cases, grade 1 in 23, grade 2 in 65, and grade 3 in 19. There were no significant correlations between DISH grade and clinical scores. However, there was a significant difference in the prevalence of neck pain (but not in back pain or low back pain) among the three grades. Interestingly, DISH localized in the thoracic spine (grade 1) may create overload at the cervical spine and lead to neck pain in patients with cervical OPLL. Conclusion: This study is the first prospective multicenter cross-sectional comparison of subjective outcomes in patients with cervical OPLL according to the presence or absence of DISH. The severity of DISH was partially associated with the prevalence of neck pain.

This study aimed to clarify whether ossification predisposition influences clinical symptoms including pain, restriction of activities of daily living, and quality of life in patients with cervical ossification of the posterior longitudinal ligament (OPLL). Cervical ossification predisposition potentially causes neurologic dysfunction, but the relationship between clinical symptoms and radiologic severity of OPLL has not yet been investigated. Data were prospectively collected from 16 institutions across Japan. We enrolled 239 patients with cervical OPLL. The primary outcomes were patient-reported outcomes, including visual analog scale (VAS) pain scores and other questionnaires. Whole-spine computed tomography images were obtained, and correlations were investigated between clinical symptoms and radiologic findings, including the distribution of OPLL, the sum of the levels where OPLL was present (OP-index), and the canal narrowing ratio (CNR) grade. The cervical OP-index was Grade 1 in 113 patients, Grade 2 in 90, and Grade 3 in 36. No significant correlations were found between radiologic outcomes and VAS pain scores. The cervical OP-index was associated with lower extremity function, social dysfunction, and locomotive function. The CNR grade was not correlated with clinical symptoms, but Grade 4 was associated with lower extremity dysfunction. Thickness and extension of ossified lesions may be associated with lower extremity dysfunction in cervical OPLL.

While bracing is the standard conservative treatment for acute osteoporotic compression fracture, the efficacy of different brace treatments has not been extensively studied. We aimed to clarify and compare the preventive effect of the different brace treatments on the deformity of the vertebral body and other clinical results in this patient cohort. This multicenter nationwide prospective randomized study included female patients aged 65⁻85 years with acute one-level osteoporotic compression fractures. We assigned patients within four weeks of injury to either a rigid-brace treatment or a soft-brace treatment. The main outcome measure was the anterior vertebral body compression percentage at 48 weeks. Secondary outcome measures included scores on the European Quality of Life-5 Dimensions (EQ-5D), visual analog scale (VAS) for lower back pain, and the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ). A total of 141 patients were assigned to the rigid-brace group, whereas 143 patients were assigned to the soft-brace group. There were no statistically significant differences in the primary outcome and secondary outcome measures between groups. In conclusion, among patients with fresh vertebral compression fractures, the 12-week rigid-brace treatment did not result in a statistically greater prevention of spinal deformity, better quality of life, or lesser back pain than soft-brace.

Ossification of the Posterior Longitudinal Ligament (OPLL) is a disease that is characterized by the ectopic calcification of the ligament; however, the pathogenesis of OPLL remains to be investigated. We attempted to identify the in vivo role of Runx2, a master regulator of osteoblast differentiation and skeletal mineralization, in the pathogenesis of OPLL. The expression of Runx2 in the ligament was examined using in situ hybridization and immunohistochemistry and by monitoring the activity of a LacZ gene that was inserted into the Runx2 gene locus. To investigate the functional role of Runx2, we studied ENPP1(ttw/ttw) mice, a mouse model of OPLL, that were crossed with heterozygous Runx2 mice to decrease the expression of Runx2, and we performed histological and quantitative radiological analyses using 3D-micro CT. Runx2 was expressed in the ligament of wild-type mice. The induction of Runx2 expression preceded the development of ectopic calcification in the OPLL-like region of the ENPP1(ttw/ttw) mice. Runx2 haploinsufficiency ameliorated the development of ectopic calcification in the ENPP1(ttw/ttw) mice. Collectively, this study demonstrated that Runx2 is expressed in an OPLL-like region, and its elevation is a prerequisite for developing the complete OPLL-like phenotype in a mouse model of OPLL.