Journal of orthopaedic research : official publication of the Orthopaedic Research Society
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Adolescent idiopathic scoliosis (AIS) is a common disorder with a strong genetic predisposition. Associations between AIS and common single nucleotide polymorphisms (SNPs) in estrogen receptor genes have been reported. rs9340799 in the gene for estrogen receptor α (ESR1) is reported to be associated with curve severity in Japanese and with AIS predisposition and curve severity in Chinese. In addition, rs1256120 in the gene for estrogen receptor β (ESR2) is reported to be associated with AIS predisposition and curve severity in Chinese. ⋯ To examine the association between AIS and estrogen receptor genes, we investigated the association of rs9340799 and rs1256120 with AIS predisposition and curve severity using a large Japanese population, consisting of 798 AIS patients and 637 sex-matched controls. We found no association of either SNP with AIS predisposition or curve severity in the Japanese population. Considering the statistical power of the present study and the limitations of the previous reports, we conclude that the associations of rs9340799 and rs1256120 with AIS predisposition and curve severity are negative.
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Low-magnitude high-frequency vibration (LMHFV) (35 Hz, 0.3 g) accelerates fracture healing by enhancing callus formation and mineralization for both normal and osteoporotic rats in our previous studies.1,2 We hypothesized that LMHFV enhances fracture healing through bone remodeling. Ibandronate was used to suppress LMHFV-stimulated bone remodeling and changes in remodeling were investigated to verify our hypothesis. Closed femoral fractures were created in 80 osteoporotic female Sprague-Dawley rats. ⋯ LMHFV partially reversed the inhibition of bone remodeling by ibandronate suggested LMHFV had an opposite effect on bone remodeling to ibandronate. In conclusion, LMHFV accelerated fracture healing by enhancing bone remodeling and the administration of ibandronate can impair this enhancement. LMHFV has great potential in improving fracture outcome clinically.
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The primary function of the disc is mechanical; therefore, degenerative changes in disc mechanics and the interactions between the annulus fibrosus (AF) and nucleus pulposus (NP) in nondegenerate and degenerate discs are important to functional evaluation. The disc experiences complex loading conditions, including mechanical interactions between the pressurized NP and the surrounding fiber-reinforced AF. Our objective was to noninvasively evaluate the internal deformations of nondegenerate and degenerate human discs under axial compression with flexion, neutral, and extension positions using magnetic resonance imaging and image correlation. ⋯ Degenerated discs exhibited higher compressive axial and tensile radial strains, which suggest that load distribution through the disc subcomponents are altered with degeneration, likely due to the depressurized NP placing more of the applied load directly on the AF. The posterior AF exhibited higher compressive axial and higher tensile radial strains than the other AF regions, and the strains were not correlated with degeneration, suggesting this region undergoes high strains throughout life, which may predispose it to failure and tears. In addition to understanding internal disc mechanics, this study provides important new data into the changes in internal strain with degeneration, data for validation of finite element models, and provides a technique and baseline data for evaluating surgical treatments.
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It is generally supposed that the pattern of fracture healing in trabecular metaphyseal bone differs from that of diaphyseal fractures. However, few experimental studies to date have been performed, even though clinically many fractures occur in metaphyseal bone. Particularly, the influence of biomechanical factors has not yet been investigated under standardized conditions. ⋯ For strains larger than 20% fibrocartilage layers were observed. Low IFS (<5%) led to intramembranous bone formation, whereas higher strains additionally provoked endochondral ossification or fibrocartilage formation. It is therefore proposed that metaphyseal bone healing follows similar biomechanical principles as diaphyseal healing.
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The aim of this study was to evaluate the effect of strontium ranelate (SrR) on fracture healing in the osteoporotic rat model. Forty female Sprague-Dawley rats aged 3 months were enrolled in the study. Osteoporosis was induced by bilateral ovariectomy and subsequent daily heparin injection started 1 week after surgery and lasted for 4 weeks. ⋯ SrR-treated group had mature woven bone or predominantly woven bone compared with osteoporotic control group (p = 0.038). SrR-treated group's callus maturity was significantly higher than control group (p = 0.001). SrR is associated with better fracture healing in the osteoporotic rat model.