Published papers

Rheumatoid arthritis (RA) is a multifactorial disease caused by genetic and environmental factors: however, precise molecular mechanisms underlying its pathogenesis remain largely unknown. Treatment of RA patients with disease-modifying biological agents occasionally promotes Mycobacterium tuberculosis infection or recurrence of M. tuberculosis, although how infection promotes arthritis has not been characterized. Here, we found that arthritis phenotypes in a collagen-induced mouse model were evident only when killed M. tuberculosis was co-administered. Treatment of cultured macrophages with killed M. tuberculosis promoted production of IL-6, a major inflammatory cytokine in RA patients, while similar treatment of TLR2-deficient macrophages failed to induce IL-6 expression. Arthritis scores, joint destruction, and serum IL-6 levels were all significantly ameliorated in TLR2-deficient compared with wild-type mice, even in animals treated with killed M. tuberculosis. These results suggest that M. tuberculosis infection enhances arthritis development and that TLR2 could serve as a therapeutic target for some forms of the disease. © 2014 The Japanese Society for Bone and Mineral Research and Springer Japan.

STUDY DESIGN.: A retrospective, observational, and multicenter study. OBJECTIVE.: To identify the ideal lower instrumented vertebra (LIV) to prevent distal adding-on after surgical correction of Lenke type 2A curve. SUMMARY OF BACKGROUND DATA.: LIV level may affect the risk of postsurgical adding-on. The choice of the last touching vertebra (LTV) - the most caudal vertebra of the main thoracic curve that touches the central sacral vertical line when standing - as an appropriate LIV has been validated for Lenke type 1A but not type 2A curve. METHODS.: Radiographs obtained before, immediately after, and 2 years after surgery were evaluated for 116 consecutive patients who underwent posterior thoracic fusion surgery for Lenke type 2A curve. The LIV was proximal to the LTV in 18 patients (PLTV), distal in 43 (DLTV), and at the LTV in 55 (ALTV). Significant independent factors associated with adding-on were analyzed first by univariate analysis, and then by stepwise logistic regression analysis. RESULTS.: Distal adding-on was present in 16 patients (13.8%) at follow-up: 9 PLTV (50.0%), 3 DLTV (7.0%), and 4 ALTV (7.3%). Adding-on was significantly more common in the PLTV group. One PLTV-group patient required revision surgery to treat adding-on. Univariate analysis identified the following significant factors associated with adding-on: the T2-T5 kyphosis angle and shoulder height before, immediately after, and 2 years after surgery; the lumbar Cobb angle at the 2-year follow-up; the 2-year postoperative lumbar curve correction rate; and the difference between the LIV and the end vertebra, neutral vertebra, and LTV levels. Significant independent risk factors identified by stepwise logistic regression analysis included the clavicle angle at follow-up, the correction rate of the lumbar curve immediately after surgery, and the difference between the LIV and LTV levels. CONCLUSION.: A LIV at or distal to the LTV may prevent postoperative adding-on in Lenke type 2A curve. © 2014 Lippincott Williams and Wilkins.

The objective of this study was to quantify the three-dimensional spatial strain distribution of a scoliotic spine by nonhomogeneous transformation without using a statistically averaged reference spine. The shape of the scoliotic spine was determined from computed tomography images from a female patient with adolescent idiopathic scoliosis. The shape of the scoliotic spine was enclosed in a rectangular grid, and symmetrized using a thin-plate spline method according to the node positions of the grid. The node positions of the grid were determined by numerical optimization to satisfy symmetry. The obtained symmetric spinal shape was enclosed within a new rectangular grid and distorted back to the original scoliotic shape using a thin-plate spline method. The distorted grid was compared to the rectangular grid that surrounded the symmetrical spine. Cobb's angle was reduced from 35° in the scoliotic spine to 7° in the symmetrized spine, and the scoliotic shape was almost fully symmetrized. The scoliotic spine showed a complex Green-Lagrange strain distribution in three dimensions. The vertical and transverse compressive/tensile strains in the frontal plane were consistent with the major scoliotic deformation. The compressive, tensile and shear strains on the convex side of the apical vertebra were opposite to those on the concave side. These results indicate that the proposed method can be used to quantify the three-dimensional spatial strain distribution of a scoliotic spine, and may be useful in quantifying the deformity of scoliosis. © 2013 Elsevier Ltd.

Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common musculoskeletal disease among people after middle age. The OPLL presents with serious neurological abnormalities due to compression of the spinal cord and nerve roots. The OPLL is caused by genetic and environment factors; however, its etiology and pathogenesis still remain to be elucidated. To determine the susceptibility loci for OPLL, we performed a genome-wide linkage study using 214 affected sib-pairs of Japanese. In stratification analyses for definite cervical OPLL, we found loci with suggestive linkage on 1p21, 2p22-2p24, 7q22, 16q24 and 20p12. Fine mapping using additional markers detected the highest non-parametric linkage score (3.43, P = 0.00027) at D20S894 on chromosome 20p12 in a subgroup that had no complication of diabetes mellitus. Our result would shed a new light on genetic aspects of OPLL. © The Japanese Society for Bone and Mineral Research and Springer Japan 2012.

This prospective study compares the radiographic and clinical results of posterior correction and fusion surgery for adolescent idiopathic scoliosis (AIS) using stainless steel and titanium alloy instruments. The subjects consisted of 65 AIS patients who underwent posterior correction and fusion surgeries using a 5.5-mm-diameter rod at a single institution. Of these, 27 patients were treated using stainless steel instruments (S group) and 38 were treated using titanium alloy instruments (T group). The mean age at the time of surgery was 14.4 ± 3.5 years. The radiographic findings, intra-operative time, estimated blood loss, perioperative complications, and SRS-22 (a patient questionnaire used in the clinical evaluation of idiopathic scoliosis outcomes) were examined. The mean preoperative Cobb angle of the major curve was 62.5 ± 17.2° in the S group and 57.8 ± 13.2° in the T group (p = 0.407). Postoperatively, the curves were corrected to 11.2 ± 10.5° and 10.3 ± 8.5° (p = 0.384), with mean correction rates of 83.4 ± 12.2% and 83.1 ± 11.6% (p = 0.940), respectively. At the final follow-up, although the mean correction loss was slightly larger in the S group (4.4 ± 5.2°) compared with that in the T group (2.3 ± 5.5°), the values were not significantly different (p = 0.118). The coronal balance and sagittal balance were also not significantly different between the two groups at the final follow-up. The function, pain, and mental health sub-scores and the total score for SRS-22 show a tendency for better outcomes in the T group; however, there were no significant differences between the two groups. Thus, there was no statistical difference in radiographical and clinical outcomes between AIS patients treated surgically using stainless steel instruments and those treated using titanium alloy instruments.

We have developed novel calcium-phosphate cements (CPCs) based on the chelate-setting mechanism of inositol phosphate (IP6) using hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP) and α-TCP as starting materials. These cements (IP6-HAp, IP6-β-TCP and IP6-α-TCP cements) have different bioresorbability due to the chemical composition of starting materials. In the present study, biocompatibility and bioresorbability of the above three cements and commercially available cement (BiopexR-R) was histologically evaluated in vivo using rabbit model for 4, 8, and 24 weeks, in addition to their dissolution in vitro. The dissolution of these cements increased in the order of IP6-HAp, IP6-β-TCP and IP6-α-TCP cements. The newly-formed bones were directly in contact with both the IP6-HAp and BiopexR-R cement specimens. As for the IP6-β-TCP and IP6-α-TCP cements, newly-formed bones were formed time-dependently slightly apart from the cement specimens. Resorption rate for BiopexR-R, IP6-HAp, IP6-β-TCP, and IP6-α-TCP cements after 24 weeks implantation were of 7.2, 5.0, 13.7, and 16.2%, respectively, compared to original cements. The present chelate-setting cements with different bioresorbability are promising candidates for application as the novel CPCs. © (2013) Trans Tech Publications, Switzerland.

Background: Although posterior correction and fusion surgery using pedicle screws carries the risk of vascular injury, a massive postoperative hemothorax in a patient with adolescent idiopathic scoliosis (AIS) is quite rare. We here report a case of a 12-year-old girl with AIS who developed a massive postoperative hemothorax. Case presentation. The patient had a double thoracic curve with Cobb angles of 63° at T2-7 and 54° at T7-12. Posterior correction and fusion surgery was performed using a segmental pedicle screw construct placed between T2 and T12. Although the patient's respiration was stable during the surgery, 20 minutes after removing the trachea tube, the patient's pulse oximetry oxygen saturation suddenly decreased to 80%. A contrast CT scan showed a massive left hemothorax, and a drainage tube was quickly inserted into the chest. The patient was re-intubated and a positive end-expiratory pressure of 5 cmH§ssub§2§esub§O applied, which successfully stopped the bleeding. The patient was extubated 4 days after surgery without incident. Based on contrast CT scans, it was suspected that the hemothorax was caused by damage to the intercostal arteries or branches during pedicle probing on the concave side of the upper thoracic curve. Extensive post-surgical blood tests, echograms, and CT and MRI radiographs did not detect coagulopathy, pulmonary or vascular malformation, or any other possible causative factors. Conclusion: This case underscores the potential risk of massive hemothorax related to thoracic pedicle screw placement, and illustrates that for this serious complication, respiratory management with positive airway pressure, along with a chest drainage tube, can be an effective treatment option. © 2013 Ogura et al.; licensee BioMed Central Ltd.

Background Although microendoscopic discectomy (MED) is a minimally invasive surgical method for lumbar disc herniation (LDH), early postoperative recurrence may outweigh that advantage. The purpose of the present study was to retrospectively investigate the recurrence rate after MED for LDH and to determine the risk factors for recurrence in patients treated by a single surgeon. Materials and Methods The study included 344 patients who underwent MED (213 males and 131 females; mean age, 39.3 years; age range, 11-82 years; mean follow-up, 3.6 years; follow-up range, 2.0-6.5 years). The clinical outcomes were evaluated using the Japanese Orthopedic Association Score for Low Back Pain (JOA score). Recurrence factors investigated by logistic regression analysis included age; sex; level, laterality, and classified type of LDH; occupation; sports activity; and learning curve of the surgeon. Results LDH recurrence was observed in 37 patients (10.8%). It was observed at the same level in the ipsilateral side as the original LDH in 30 patients, in the contralateral side in three patients, and at a level adjacent to the original level in four patients. The mean time interval between MED and the recurrence was 16.6 months (range, 0.5-52 months). Twenty patients (54.1%) developed recurrence within 1 year after MED. Twenty-two patients (59.5%) were treated by revision surgery (MED in 20 patients and microdiscectomy in two patients), and 15 patients (40.5%) were treated conservatively. The mean JOA score of all the patients was 14.7 ± 3.5 before surgery and 26.5 ± 2.2 at the final follow-up, yielding an average recovery rate of 82.3 ± 15.7%. The recovery rate was 83.1 ± 14.8% in patients without recurrence and 75.7 ± 20.4% in patients with recurrence (p = 0.006). By logistic regression analysis, we identified migration of LDH as a significant factor related to recurrence. The patients with caudal migration of LDH had recurrence more frequently (19.0%) than those with rostral migration (12.5%) or without migration (10.2%) (p = 0.04; odds ratio, 2.0; 95% confidence interval, 1.0-3.8). Conclusion The recurrence rate and reoperation rate for LDH after MED were comparable to those of conventional discectomy. More than half of the cases of recurrence occurred at an early postoperative phase, and patients with caudally migrated LDH experienced recurrence significantly more often than those with rostrally migrated or nonmigrated LDH. ©2013 Georg Thieme Verlag KG Stuttgart, New York.

Biodegradable α-tricalcium phosphate (α-TCP) cement based on the chelate-setting mechanism of inositol phosphate (IP6) was developed. This paper examined the effect of the milling time of α-TCP powder on the material properties of the cement. In addition, biocompatibility of the result cement in vitro using osteoblasts and in vivo using rabbit models will be studied as well. The α-TCP powders were ballmilled using ZrO2 beads in pure water for various durations up to 270 minutes, with a single-phase α-TCP obtained at ballmilling for 120 minutes. The resulting cement was mostly composed of α-TCP phase, and the compressive strength of the cement was 8.5±1.1 MPa, which suggested that the cements set with keeping the crystallite phase of starting cement powder. The cell-culture test indicated that the resulting cements were biocompatible materials. In vivo studies showed that the newly formed bones increased with milling time at a slight distance from the cement specimens and grew mature at 24 weeks, and the surface of the cement was resorbed by tartrate-resistant acid phosphatase-(TRAP-)positive osteoclast-like cells until 24 weeks of implantation. The present α-TCP cement is promising for application as a novel paste-like artificial bone with biodegradability and osteoconductivity. © 2013 Toshiisa Konishi et al.

Hydroxyapatite (HAp), with its high biocompatibility and osteoconductivity, readily absorbs proteins, amino acids and other substances, which in turn favor the adsorption and colonization of bacteria. To prevent bacterial growth and biofilm formation on HAp discs, silver-containing (1-20 mol%) HAp (Ag-HAp) powders were synthesized using an ultrasonic spray pyrolysis (USSP) technique. The X-ray diffraction (XRD) peaks were very broad, indicating low crystallinity, and this induced the release of Ag+ ions from Ag-HAp powders. In addition, a gradual increase in Ca2+ ion release was observed. These results suggest that dissolution of Ca2+ ion in Ag-HAp triggered the release of Ag+ ions. The antimicrobial efficacy of Ag-HAp disc was tested against Staphylococcus aureus. Samples with Ag contents of more than 5 mol%were found to be highly effective against bacterial colonization and biofilm formation in vitro. In vivo antibacterial tests using bioluminescent strains also showed reductions in the viability of bacteria with Ag-HAp (5 mol%) discs. Biocompatibility tests using a modified Transwell® insert method showed that Ag-HAp (5 mol%) discs have negative effects on osteoblast proliferation. These results indicate that Ag-HAp (5 mol%) has effective antibacterial activity and good biocompatibility both in vitro and in vivo together with good biocompatibility, thus confirming its utility as a bactericidal material. © 2013 Elsevier B.V. All rights reserved.

Purpose: Although the occurrence and progression of AIS has been linked to low bone mineral density (BMD), the relationships between spinal curvature and bilateral differences in proximal femur BMD are controversial. Few correlation studies have stratified patients by curve type. The purpose of this study was to evaluate the relationships between spinal coronal profile and bilateral differences in proximal femur BMD in patients with adolescent idiopathic scoliosis (AIS). Methods: This study included 67 patients with AIS who underwent posterior correction and fusion surgery between January 2009 and October 2011. The mean age at the time of surgery was 17.4 ± 4.1 years. Bilateral proximal femur BMD was measured before surgery by dual-energy X-ray absorptiometry. We compared the proximal femur BMDs by determining the bilateral BMD ratio (left proximal femur BMD divided by that of the right). We evaluated correlations between coronal parameters, obtained from preoperative radiographs, and the BMD ratio using Pearson's correlation analysis. Results: Patients with Lenke type 1 curve (48; all with a right convex curve) had a mean bilateral proximal femur BMD ratio of 1.00 ± 0.04. Patients with Lenke type 5 curve (19; all with a left convex curve) had a mean bilateral proximal femur BMD ratio of 0.94 ± 0.04, indicating that the BMD in the proximal femur on the right side (concave) was greater than that in the left (convex). Coronal balance was significantly correlated with the BMD ratio in both the Lenke type 1 and type 5 groups, with a correlation coefficient of 0.46 and 0.50, respectively. Conclusions: The bilateral proximal femur BMD ratio was significantly correlated with the coronal balance in AIS patients. When the C7 plumb line was shifted toward one side, the BMD was greater in the contralateral proximal femur. © 2013 Springer-Verlag Berlin Heidelberg.

Spinal extradural arachnoid cyst (SEDAC) is a cyst in the spinal canal that protrudes into the epidural space from a defect in the dura mater. Most cases are sporadic; however, three familial SEDAC cases have been reported, suggesting genetic etiological factors. All familial cases are associated with lymphedema-distichiasis syndrome (LDS), whose causal gene is FOXC2. However, FOXC2 mutation analysis has been performed in only 1 family, and no mutation analysis has been performed on sporadic (non-familial) SEDACs. We recruited 17 SEDAC subjects consisting of 2 familial and 7 sporadic cases and examined FOXC2 mutations by Sanger sequencing and structural abnormalities by TaqMan copy number assay. We identified 2 novel FOXC2 mutations in 2 familial cases. Incomplete LDS penetrance was noted in both families. Four subjects presented with SEDACs only. Thus, SEDAC caused by the heterozygous FOXC2 loss-of-function mutation should be considered a feature of LDS, although it often manifests as the sole symptom. Seven sporadic SEDAC subjects had no FOXC2 mutations, no symptoms of LDS, and showed differing clinical characteristics from those who had FOXC2 mutations, suggesting that other gene(s) besides FOXC2 are likely to be involved in SEDAC. © 2013 Ogura et al.

Lumbar disc degeneration (LDD) is associated with both genetic and environmental factors and affects many people worldwide. A hallmark of LDD is loss of proteoglycan and water content in the nucleus pulposus of intervertebral discs. While some genetic determinants have been reported, the etiology of LDD is largely unknown. Here we report the findings from linkage and association studies on a total of 32,642 subjects consisting of 4,043 LDD cases and 28,599 control subjects. We identified carbohydrate sulfotransferase 3 (CHST3), an enzyme that catalyzes proteoglycan sulfation, as a susceptibility gene for LDD. The strongest genome-wide linkage peak encompassed CHST3 from a Southern Chinese family-based data set, while a genome-wide association was observed at rs4148941 in the gene in a meta-analysis using multiethnic population cohorts. rs4148941 lies within a potential microRNA-513a-5p (miR-513a-5p) binding site. Interaction between miR-513a-5p and mRNA transcribed from the susceptibility allele (A allele) of rs4148941 was enhanced in vitro compared with transcripts from other alleles. Additionally, expression of CHST3 mRNA was significantly reduced in the intervertebral disc cells of human subjects carrying the A allele of rs4148941. Together, our data provide new insights into the etiology of LDD, implicating an interplay between genetic risk factors and miRNA.

In women, estrogen deficiency after menopause frequently accelerates osteoclastic bone resorption, leading to osteoporosis, the most common skeletal disorder. However, mechanisms underlying osteoporosis resulting from estrogen deficiency remain largely unknown. Here we show that in bone-resorbing osteoclasts, estrogendependent destabilization of hypoxia-inducible factor 1 alpha (HIF1?), which is unstable in the presence of oxygen, plays a pivotal role in promoting bone loss in estrogen-deficient conditions. In vitro, HIF1? was destabilized by estrogen treatment even in hypoxic conditions, and estrogen loss in ovariectomized (Ovx) mice stabilized HIF1? in osteoclasts and promoted their activation and subsequent bone loss in vivo. Osteoclast-specific HIF1? inactivation antagonized bone loss in Ovx mice and osteoclast-specific estrogen receptor alpha deficient mice, both models of estrogen-deficient osteoporosis. Oral administration of a HIF1? inhibitor protected Ovx mice from osteoclast activation and bone loss. Thus, HIF1? represents a promising therapeutic target in osteoporosis.

Background: Several risk factors have been proposed for intervertebral disc degeneration (DD) among adolescent athletes. However, the causes of DD are not well understood, and there have been few prospective studies evaluating DD in adolescents. Purpose: To identify risk factors for DD among adolescent American football (AF) players. Study Design: Cohort study (prevalence); Level of evidence, 2. Methods: This study investigated the relationships between the progression of DD and the following factors: lumbar spine abnormalities on baseline radiographs, body mass index, AF position played (lineman or other), and length of playing career (2 full competitive AF seasons or<2 seasons). Included were 192 students who joined a top-ranked high school AF team from 2004 to 2008. Of these, 160 played for 2 full competitive AF seasons. The remaining 32 players, who stopped before completing 2 seasons, were used as a control group. Baseline radiographs and lumbar magnetic resonance imaging (MRI) scans were obtained when the players enrolled in the AF team in May, and follow-up lumbar MRI scans were obtained 2 years later at the end of their second academic year in March. Disc degeneration was measured by the signal intensity of the nucleus pulposus, and its progression was evaluated by multiple regression analysis of decreases in signal intensity. Also analyzed was the relationship between DD and low back pain (LBP). Results: The mean decrease in signal intensity of the nucleus pulposus was 4.30% ± 11.63% in players who completed 2 AF seasons and 1.41% ± 10.03% in those who did not (P = .12). Mean visual analog scale scores for LBP at follow-up were significantly higher (P = .001) in players who had played for 2 full seasons (2.67 ± 2.81) than in those with a shorter career (0.99 ± 1.61). Decreases in signal intensity of the nucleus pulposus after 2 years of playing AF related significantly to playing a lineman position (partial regression coefficient, 3.47%), the presence of Schmorl nodes (partial regression coefficient, 3.58%), and disc herniation (partial regression coefficient, 4.09%). Conclusion: Significant risk factors for DD progression in high school AF players included playing a lineman position, the presence of Schmorl nodes, and disc herniation. Continuing to play AF through 2 years of high school was a risk factor for the onset of LBP. © 2013 The Author(s).

Adolescent idiopathic scoliosis (AIS) is the most common spinal deformity, affecting around 2% of adolescents worldwide. Genetic factors play an important role in its etiology. Using a genome-wide association study (GWAS), we recently identified novel AIS susceptibility loci on chromosomes 10q24.31 and 6q24.1. To identify more AIS susceptibility loci relating to its severity and progression, we performed GWAS by limiting the case subjects to those with severe AIS. Through a two-stage association study using a total of ∼12,000 Japanese subjects, we identified a common variant, rs12946942 that showed a significant association with severe AIS in the recessive model (P = 4.00×10-8, odds ratio [OR] = 2.05). Its association was replicated in a Chinese population (combined P = 6.43×10-12, OR = 2.21). rs12946942 is on chromosome 17q24.3 near the genes SOX9 and KCNJ2, which when mutated cause scoliosis phenotypes. Our findings will offer new insight into the etiology and progression of AIS. © 2013 Miyake et al.