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Objectives: This study aimed to evaluate the dentin bond performance of various resin luting cement (RLC) systems combined with universal adhesives in different luting strategies. Materials and methods: Three self-adhesive resin luting cements (SRLCs) were used with universal adhesives as primers. Twelve specimens per group were prepared to measure shear bond strength (SBS) under distinct luting strategies in etch-&-rinse and self-etch modes. Regarding luting strategies, the bonded specimens were categorized into four groups based on tooth primer application and the curing mode of the SRLC paste: (i) with light irradiation of the tooth primer (wL) + dual-cure mode (DC) of the SRLC paste, (ii) wL + self-cure mode (SC) of the SRLC paste, (iii) without light irradiation of the tooth primer (woL) + DC mode of the SRLC paste, and (iv) woL + SC mode of the SRLC paste. Specimens were also subjected to different storage conditions: 24 h in water (baseline condition) and 10,000 cycles of thermal cycling. Results: Luting strategy, storage condition, and SRLC system type significantly influenced dentin SBS values in both etching modes. Notably, certain SRLCs exhibited significantly higher dentin SBS when the primer was light-irradiated compared with no primer irradiation. Conclusion: Most SRLCs demonstrated higher dentin bond strength with light-irradiated primers, suggesting potential enhancement of dentin bond performance via primer light irradiation.Significance: Although touch-cure polymerization can improve bond performance, its efficacy varies among SRLCs. Light irradiation of the primer and the SRLC paste might enhance the dentin bond performance of SRLCs combined with universal adhesives. [ABSTRACT FROM AUTHOR]

Introduction: The cervical sagittal vertical axis (cSVA) as another aspect of cervical alignment been recognized as one of the important factors affecting the pain and disability outcomes of cervical spine surgery. The purpose of the present study was to analyze the risk factors for increasing cSVA after cervical laminoplasty for cervical spondylotic myelopathy (CSM). Materials and methods: This retrospective study included 110 consecutive patients (68 males and 42 females, average age 72.6 years) who underwent laminoplasty for CSM between January 2007 and June 2018. We recorded the operative time, blood loss, Japanese Orthopaedic Association (JOA) score and the recovery rate. Radiological measurements were performed to analyze the following parameters: pre- and 1-year postoperative McGregor's slope (McGS), occiput to C2 Cobb angle (O–C2 angle), C2–C7 Cobb angle (C2–7 angle), T1-slope (T1S), C2–7 SVA (cSVA) and calculated the change (Δ). Patients were divided into two groups according to whether ΔcSVA was positive or negative. We also used Spearman's correlation coefficient and multiple regression analysis. Results: ΔC2–7 angle, ΔT1S—preoperative C2–7 angle, ΔO–C2 angle were different between the two groups significantly. Correlation analysis between the ΔcSVA and the various sagittal parameters showed some independent explanatory factors including the ΔC2–7 angle (r = − 0.25, p = 0.010), T1S—preoperative C2–7 angle (r = − 0.28, p = 0.004), postoperative O–C2 angle (r = 0.26, p = 0.007), ΔO–C2 angle (r = 0.37, p = 0.001). Multiple regression analysis revealed that ΔcSVA was associated with the T1S—preoperative C2–7 angle (β = − 0.25, p = 0.034) and ΔO–C2 angle (β = 0.32, p = 0.001). Conclusions: The imbalance between T1S and preoperative C2–7 angle influences the change of cSVA after cervical laminoplasty. If cSVA increases postoperatively, the O–C2 angle increases to compensate and maintain the horizontal gaze. [ABSTRACT FROM AUTHOR]

Objectives: The present study aimed to investigate the changes in the enamel bond strengths of universal adhesives in the early phase of specimen creation and evaluate the effect of double-layer application on enamel bond effectiveness using different etching modes. Method: Four universal adhesives, namely Clearfil Universal Bond Quick, G-Premio Bond, Scotchbond Universal, and Tokuyama Universal Bond, were used. Clearfil SE Bond two-step self-etch adhesive system was used as a comparison. Fifteen specimens per group were used for determining the shear bond strength (SBS) to bovine enamel in the etch-and-rinse or self-etch mode. The adhesive was applied to specimens in accordance with the manufacturers' instructions (single-layer application), or the adhesive was applied twice (double-layer application). The bonded specimens were stored in distilled water at 37 °C for 5 min or 1, 6, 12, or 24 h before SBS testing. The flexural properties of the resin composite Clearfil AP-X were measured for the same storage periods. Results: All universal adhesives exhibited increased SBS values with prolonged storage periods regardless of the application technique or etching mode used. Double-layer application was associated with higher SBS values than single-layer application for most universal adhesives over the same storage period. Conclusion: Phosphoric acid pre-etching and double-layer application of universal adhesives resulted in increased enamel bond strength in the early phase of specimen bonding. Clinical relevance: Care should be taken when using universal adhesives in the self-etch mode for enamel bonding because the enamel adhesion is sensitive to the duration after filling. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to compare dentin bond durability under different degradation conditions between two etch-and-rinse (ER) systems and a universal adhesive in ER mode. Method: This study used a universal adhesive [Scotchbond Universal (SU)], a three-step ER adhesive [Scotchbond Multi-Purpose Plus (SM)], and a two-step ER adhesive [Single Bond Plus (SB)]. A phosphoric acid-etching agent was applied to bovine dentin prior to the application of either a primer or the adhesive. After acid etching, bonding procedures were conducted. The specimens were divided into three group classes: (1) subjected to 10,000, 30,000, or 50,000 thermal cycles (TC); (2) stored in distilled water at 37 °C for 6 months or 1 year (WS); and (3) stored in distilled water for 24 h (baseline). Shear bond strength (SBS) tests were conducted. Results: SB showed a higher baseline SBS than the other adhesives. Defining the baseline SBS value for each adhesive system as 100%, TC groups ranged from 56.1 to 70.3% for SM, from 98.4 to 103.7% for SB, and from 120.3 to 126.7% for SU. WS groups ranged from 66.2 to 71.4% for SM, from 98.1 to 103.3% for SB, and from 102.5 to 118.1% for SU. Conclusions: Although SB showed relatively stable dentin bond performance under all degradation conditions, SM showed decreased dentin SBS with prolonged degradation. SU did not show any significant decrease in SBS from the baseline under any degradation condition. Clinical relevance: The universal adhesive showed comparable adhesive performance with the two-step ER adhesive. [ABSTRACT FROM AUTHOR]

Background: Subsidence in anterior cervical corpectomy and fusion (ACCF) for cervical degenerative disease (CDD) are constantly observed during the postoperative course. Although kyphotic change of cervical alignment occurred frequently in cervical pyogenic spondylitis (CPS) postoperatively, studies on the postoperative change in segmental angle for CPS are limited. This study aimed to analyze cervical alignment after single-level ACCF using autologous bone graft without spinal instrumentation for CPS compared with that for CDD. Methods: Six patients underwent single-level ACCF using autologous bone graft without spinal instrumentation for CPS. The control group included 18 age-matched patients who underwent single-level ACCF using autologous bone graft for CDD without spinal instrumentation for the same duration. Cervical and lateral plain radiographs and computed tomography scans were taken. The Frankel classification was used to assess the neurological status preoperatively, postoperatively, and at 2-year follow-up for CPS. Results: At 2-year follow-up, the average segmental angle at the fusion level was − 12.2° ± 6.9° for CPS and − 5.2° ± 7.6° for CDD (p = 0.04). Changes in segmental angle at the fusion level were − 7.2 ± 9.0° for CPS and − 1.1° ± 7.1° for CDD (p = 0.02). At 2-year follow-up, the average anterior segmental fusion height was 23.4 ± 1.7 mm for CPS and 29.1 ± 5.1 mm for CDD (p < 0.001). At 2-year follow-up, bone fusion in the CPS group was classified as grade 5 (complete fusion) in 4 patients (66.7%) and grade 4 (probable fusion) in 2 (33.3%). In the CDD group, it was grade 5 in 13 patients (72.2%) and grade 4 in 5 patients (27.8%). Overall, both groups achieved 100% bone fusion rate. The Frankel classification in all CPS cases improved or leveled off. Conclusion: Progression of segmental kyphosis angle and subsidence of graft bone were observed postoperatively on all CPS cases. However, the neurological recovery and bone union were satisfactory. [ABSTRACT FROM AUTHOR]

Introduction: The number of pelvic fractures based on osteoporosis has been increasing. The infra-acetabular screw (IAS), which connected both osseous columns, is a safe method of screw placement going through the infra-acetabular corridor (IAC). However, the specifics of the anatomy of IAC have been far from completely understood, especially in the Asian population. The purpose of our study was to reveal the details of the IAC using computed tomography (CT) data.Materials and Methods: Traumatized in-patients having pelvic CT scans from 2014 to 2016 were enrolled. Pediatric and adult patients with pelvic fractures and hip prostheses were excluded. The male/female ratio and distribution of patients' age were equalized manually; 40 male and 40 female patients were included. The IAC was measured on the plane of the inlet view (25° caudal) in multi-planar reconstructed CT images.Measurements: infra-acetabular diameter (IAD), anterior-posterior length of the IAC (APL), length from the starting point of the IAC to the medial edge of the pelvis (LME), length from the starting point of the IAC to the top of the pubic symphysis (LPS), and tilting on inlet plate (TIP).Results: Age was 59 ± 22 (mean ± SD). Height was 159 ± 11 cm, and body mass index (BMI) was 22.9 ± 4.1. IAD, APL, LME, LPS, and TIP was 4.0 ± 1.3 mm, 89.5 ± 7.1 mm, 8.7 ± 3.6 mm, 57.8 ± 4.8 mm, and 4.7 ± 5.2°, respectively. Over 20% of corridors (35 of 160) were not feasible for IAS placement, because of inadequate width (less than 3.0 mm). Nine corridors (5.6%) had curvature in IAC, which meant technically demanding to insert IAS. There was no difference in IAD between male and female patients, while APL, LME, LPS, and TIP had sex-related differences.Conclusions: Surgeons should pay attention to the fact that over 20% of IACs are not feasible for infra-acetabular screw placement even with the perfect reduction of fragments when treating acetabular fractures. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to examine the enamel bond durability of universal adhesives in the self-etch mode under 2-year water storage and thermal cycling conditions.Materials and methods: Three commercially available universal adhesives and a gold standard two-step self-etch adhesive were used. Ten specimens of bovine enamel were prepared per test group, and shear bond strength (SBS) was measured to determine the bonding durability after thermal cycling (TC) or long-term water storage (WS). The bonded specimens were divided into three groups: (1) specimens subjected to TC, where the bonded specimens were stored in 37 °C distilled water for 24 h before being subjected to 3000, 10,000, 20,000 or 30,000 TC; (2) specimens stored in 37 °C distilled water for 3 months, 6 months, 1 year or 2 year; and (3) specimens stored in 37 °C distilled water for 24 h, serving as a baseline.Results: The two-step self-etch adhesive showed significantly higher SBS than the universal adhesives tested, regardless of the type of degradation method. All universal adhesives showed no significant enamel SBS reductions in TC and WS, when compared to baseline and the other degradation conditions.Conclusions: Compared to the bond strengths obtained with the two-step self-etch adhesive, significantly lower bond strengths were obtained with universal adhesives. However, the enamel bond durability of universal adhesives was relatively stable under both degradation conditions tested.Clinical relevance: The present data indicate that the enamel bond durability of universal adhesives in the self-etch mode might be sufficient for clinical use. [ABSTRACT FROM AUTHOR]

Purpose: To describe the first case of a patient who developed acute celiac artery compression syndrome (ACACS) after extensive correction of sagittal balance on an adult spinal deformity.Methods: A 77-year-old woman presented with low back pain and spinal kyphosis deformity. We performed a two-stage correction with extreme lateral interbody fusion (XLIF), and her lumbar lordosis improved from -47° to 53°. However, after surgery, she experienced frequent vomiting and diarrhea. Contrast-enhanced computed tomography showed marked narrowing of the abdominal aorta at the L1/2 level, and both the celiac artery and superior mesenteric artery were compressed. Therefore, emergency surgery was performed. After laparotomy, we found that the small bowel exhibited an unfavorable color and that peristalsis had stopped. The aorta was compressed from the anterior direction at the upper side of the renal arteries. The median arcuate ligament (MAL) and celiac plexus were responsible for the compression. After the compression was relieved, the small bowel color and peristaltic activity improved.Results: Postoperatively, there was no recurrence of abdominal symptoms. The patient could walk with a walking frame from 3 weeks postoperatively.Conclusion: ACACS is a life-threatening complication, and therefore, it is very important that ACACS is diagnosed and treated early. Spinal deformity surgeons should be aware of the possible occurrence of this condition after extensive correction of sagittal balance on adult spinal deformity. [ABSTRACT FROM AUTHOR]

Background: Spinal meningioma is a relatively common tumor among intradural extramedullary spinal tumors. When the locus of the meningioma is located on the ventral side, tumor removal, dura mater resection, and reconstruction via a posterior approach safety become technically difficult. Methods: Twelve patients, who received surgical treatment for ventral spinal meningioma via a posterior approach, were included. There were three male and nine female patients, with an average age of 66.3 years (47-88 years). The average observation period was 55.4 months (22-132 months). In these cases, we analyzed the spinal level of tumor position, histopathological type (subtype), the grade of tumor resection (Simpson grade), pre- and post-operative walking state (Nurick grade), perioperative neurological complications, and the recurrence. Results: Spinal meningioma occurred in the cervical spinal cord in three cases, with a further nine cases in the thoracic spinal cord. Histopathologically, all 12 tumors were assessed as grade I on the WHO classification system (eight cases of meningothelial type and four cases of psammomatous type). The level of tumor resection was Simpson grade I resection for two cases and Simpson grade II resection for the remaining ten cases. The average of Nurick grade improved from 3.3 preoperatively to 1.3 postoperatively. In all cases, we identified no neurological complications. One incident of tumor recurrence was identified 11 years after an operation involving a Simpson grade II resection Conclusion: Posterior approaches provide adequate exposure to safely remove ventrally located meningioma. Posterior exposures with lateral bone resection, dentate ligament division, provide also adequate exposure for safe removal. [ABSTRACT FROM AUTHOR]

Background: The standard for rotational alignment of the tibial component in total knee arthroplasty (TKA) remains unclear. Cases often require positioning of the tibial component, prioritizing adequate coverage of resected bone surface rather than alignment with the tibial rotational axis. We investigated tibial component position in TKA, prioritizing maximum coverage of resected bone surface, and evaluated the correlation with the tibial anteroposterior (AP) axis. Methods: We analyzed preoperative computed tomography images for primary TKA in 106 cases and 157 knees, using three-dimensional planning software. Tibial component position prioritizing maximum coverage of resected bone surface was simulated, and results were compared with the AP axis. Rotational alignment angle was defined as that between a line perpendicular to the tibial AP axis and a line connecting the posterior edge of the tibial component. Results: The simulated tibial component was more externally rotated by a mean 4.5° ± 4.2°. The alignment angle showed normal distribution, but variability was large, ranging from 5.1° internal rotation to 16.2° external rotation. In 138 of 157 (87.9 %) knees, the tibial component was positioned in the externally rotated position with respect to the AP axis. The tibial component was aligned within the medial one-third of the patellar tendon in 122 of 157 (77.7 %) knees. Conclusions: The tibial component aligned using coverage prioritizing was externally rotated, although large variability was observed. Rotational alignment was optimal in 79 % of cases when the tibial component was aligned with coverage prioritizing, but hyperexternal rotation was observed in patients with severe knee deformation. [ABSTRACT FROM AUTHOR]

Background: Elderly polytrauma patients with pelvic fractures are at higher risk than young adults for severe medical outcomes and/or death in the early post-trauma phase. The aim of our study was to identify predictive factors of medical severity among geriatric polytrauma patients. Methods: We conducted a retrospective cross-sectional study of polytrauma patients treated at our center, who had a pelvic fracture and at least two other injuries with an abbreviated injury score ≥3. Our study group included 15 geriatric (mean age, 65 years) and 13 young (mean age, 39 years) adults. Factors related to medical status on admission were compared between the groups to identify those predictive of a severe medical outcome, defined by massive transfusion (>10 units of red blood cells) within the first 24 h of admission and/or death. Results: Groups were comparable in terms of injury severity score (mean, 29), systolic blood pressure, heart rate, shock index, hemoglobin level, the prothrombin time-to-international normalized ratio (PT-INR) and base deficit. Over two-third of geriatric patients required a massive transfusion, with two patients dying, compared with the death of one young patient. Among geriatric patients, predictors of a severe medical outcome were extravasation of contrast medium on computed tomography, a hemoglobin level <11 g/dl, a PT-INR >1.1 and a base deficit >2 mmol/l. Conclusions: Even with our aggressive treatment algorism of pelvic fractures, particularly for the elderly, most of the geriatric polytrauma patients with severe pelvic fractures were at a high risk of massive transfusion. Extravasation on enhanced computed tomography and abnormal levels of select blood serum markers could assist in the early identification of geriatric polytrauma patients at risk for a severe medical outcome. [ABSTRACT FROM AUTHOR]

Background: The results of prospective studies examining the association between dietary vitamin A intake and the risk of gastric cancer have often been conflicting. The objective of this study was to investigate this issue in a general Japanese population. Methods: A total of 2,467 community-dwelling Japanese subjects aged 40 years or older were followed up prospectively for 14 years. Dietary vitamin A intake was estimated using a semiquantitative food frequency method. Results: During the follow-up period, gastric cancer developed in 93 subjects. The age- and sex-adjusted incidence of gastric cancer rose progressively with increasing levels of dietary vitamin A intake: at 2.2, 3.0, 3.8, and 4.5 per 1,000 person-years for quartile groups defined by dietary vitamin A intake levels of <639, 639-837, 838-1,061, and >1,061 μg retinol equivalents (RE)/day, respectively ( P for trend <0.01). The risk of gastric cancer was significantly higher in the fourth quartile than in the first one even after multivariate adjustment [hazard ratio (HR) = 1.47, 95% confidence interval (CI) = 0.70-3.09, P = 0.30 for the second quartile; HR = 1.85, 95% CI = 0.82-4.18, P = 0.14 for the third quartile; HR = 2.96, 95% CI = 1.12-7.80, P = 0.03 for the fourth quartile]. Comparable effects of vitamin A intake were observed irrespective of the location or histological type of gastric cancer. The HR for gastric cancer increased significantly only in subjects with a combination of high vitamin A intake (>1,061 μg RE/day) and Helicobacter pylori infection. Conclusions: Our findings suggest that dietary vitamin A intake is clearly associated with the risk of gastric cancer in the general Japanese population. [ABSTRACT FROM AUTHOR]

With the current advances in spinal surgery, an understanding of the precise biological mechanism of each bone substitute is necessary for inducing successful spinal fusion. In this review, the categories of bone substitutes include allografts, ceramics, demineralized bone matrix, osteoinductive factors, autogenous platelet concentrate, mesenchymal stem cells, and gene therapy. Further, clinical studies have been evaluated by their levels of evidence in order to elucidate the precise effect of the bone substitute employed and to establish clinical guidance. This article will review both clinical studies based on evidence and basic research in current advances in order to avoid as far as possible any chances of failure in the future and to understand cellular biology in novel technologies. [ABSTRACT FROM AUTHOR]

A congenitally narrow cervical spinal canal has been established as an important risk factor for the development of cervical spondylotic myelopathy. However, few reports have described the mechanism underlying this risk. In this study, we investigate the relationship between cervical spinal canal narrowing and pathological changes in the cervical spine using positional magnetic resonance imaging (MRI). Two hundred and ninety-five symptomatic patients underwent cervical MRI in the weight-bearing position with dynamic motion (flexion, neutral, and extension) of the cervical spine. The sagittal cervical spinal canal diameter and cervical segmental angular motion were measured and calculated. Each segment was assessed for the extent of intervertebral disc degeneration and cervical cord compression. Based on the sagittal canal diameter, the subjects were classified into three groups: A, subjects with a congenitally narrow canal, diameter of less than 13 mm; B, subjects with a normal canal, diameter of 13–15 mm; C, subjects with a wide canal, diameter of more than 15 mm. When compared with Groups A and B, the disc degeneration grades at the C3-4, C5-6, and C6-7 segments and the cervical cord compression scores at the C3-4 and C5-6 segments showed significant differences. Additionally, when compare with Groups A and C, the disc degeneration grades at all segments, except C2-3, and the cervical cord compression scores at all segments, except C2-3, showed significant differences. With respect to the cervical kinematics, few differences in the kinematics were observed between Groups B and C, however, the kinematics in Group A was different with other two groups. In Group A, the segmental mobility at the C4-5 and C6-7 segments were significantly higher than those observed in Group B, and the segmental mobility at the C3-4 segment was significantly lower than that observed in Groups B or C. We demonstrated the unique pathological and kinematic traits of cervical spine that exist in a congenitally narrow canal. We hypothesize that kinematic trait associated with a congenitally narrow canal may greatly contribute to pathological changes in the cervical spine. Our results suggest that cervical spinal canal diameter of less than 13 mm may be associated with an increased risk for development of pathological changes in cervical intervertebral discs. Subsequently, the presence of a congenitally narrow canal can expose individuals to a greater risk of developing cervical spinal stenosis. [ABSTRACT FROM AUTHOR]

In the present study, we aimed to determine whether tacrolimus (FK506) and cyclosporine A act directly on human osteoclast precursors obtained from patients with rheumatoid arthritis (RA) and influence monocyte–osteoclast differentiation induced by receptor activator of NF-κB ligand (RANKL) in vitro, the stage at which differentiation was affected and the manner in which tacrolimus or cyclosporine A affected the osteoclast signaling pathway. Peripheral blood mononuclear cells (PBMCs) were isolated from RA patients and cultured in the presence of RANKL and macrophage-colony stimulating factor (M-CSF). Tacrolimus or cyclosporine A was added to these cultures to determine the effect on the osteoclast differentiation. Osteoclast formation was determined by assessing the number of tartrate resistant acid phosphatase (TRAP) staining cells and measuring the extent of lacunar resorption. The expression of osteoclast transcription factors, such as TNF receptor-associated factor 6 (TRAF6), nuclear factor of activated T cells c1 (NFATc1), c-Fos, c-Jun, microphthalmia transcription factor (MITF) and PU.1 in mononuclear cells (MNCs) was assayed by quantitative reverse transcription-polymerase chain reaction. Addition of tacrolimus or cyclosporine A resulted in a decrease in the number of TRAP-positive multinucleated cells (TRAP+ MNCs) and a decrease in the extent of lacunar resorption pit formation as compared to the control cultures; thus, human monocyte–osteoclast differentiation was more effectively inhibited at the late stage and addition of tacrolimus or cyclosporine A resulted in a decrease in the mRNA expression of NFATc1, c-Jun, and MITF at the late stage. Our results suggest that tacrolimus or cyclosporine A acts directly on human osteoclast precursors in RA patients and exerts their immunosuppressive effects on human monocyte–osteoclast formation via targeting both the calcineurin-dependent NFAT pathway and activation pathway for c-Jun or MITF. [ABSTRACT FROM AUTHOR]

A response by Masashi Miyazaki to a letter to the editor about his article "An update on bone substitutes for spinal fusion" in the May 6, 2010 issue is presented.