Highly sensitive and scalable AAO-based nano-fibre SERS substrate for sensing application.

Well-ordered periodic nanostructures are excellent substrates for many surface-enhanced Raman spectroscopy (SERS) applications. Conventional fabrication approaches such as high precision electron beam lithography or focused ion beam produce high resolution nano-features with great reproducibility at the expense of low throughput. In this work, a highly sensitive and scalable AAO-nano-fibre (ANF) SERS substrate is demonstrated by optimising the second anodisation time of the standard two-step anodisation of aluminium and performing an additional wet etching step on the resulting AAO substrate. The optimised ANF substrate exhibits SERS sensitivity that surpasses the AAO nanoholes and the metal-film-on-nanoparticles substrates. A detection limit of 0.1 nM is achieved with a signal-to-noise ratio of 2.6-3 using a low excitation power of 0.1 mW. The ANF substrate exhibits an enhancement factor of 9.28 × 106 and a standard deviation of no more than 8%. The results indicate that the highly sensitive and scalable ANF substrate is a promising substrate for commercial SERS application.

Prevalence of vitamin D insufficiency among adolescents and its correlation with bone parameters using high-resolution peripheral quantitative computed tomography.

UNLABELLED: Vitamin D deficiency and insufficiency are highly prevalent among adolescents in Hong Kong, which is a sub-tropical city with ample sunshine. Vitamin D level is significantly correlated with key bone density and bone quality parameters. Further interventional studies are warranted to define the role of vitamin D supplementation for improvement of bone health among adolescents. INTRODUCTION: The relationship between bone quality parameters and vitamin D (Vit-D) status remains undefined among adolescents. The aims of this study were to evaluate Vit-D status and its association with both bone density and bone quality parameters among adolescents. METHODS: Three hundred thirty-three girls and 230 boys (12-16 years old) with normal health were recruited in summer and winter separately from local schools. Serum 25(OH) Vit-D level, bone density and quality parameters by Dual Energy X-ray Absorptiometry (DXA) and High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT), dietary calcium intake, and physical activity level were assessed. RESULTS: Sixty-four point seven percent and 11.4 % of subjects were insufficient [25 ≤ 25(OH)Vit-D ≤ 50 nmol/L] and deficient [25(OH)Vit-D < 25 nmol/L] in Vit-D, respectively. The mean level of serum 25(OH)Vit-D in summer was significantly higher than that in winter (44.7 ± 13.6 and 35.9 ± 12.6 nmol/L, respectively) without obvious gender difference. In girls, areal bone mineral density (aBMD) and bone mineral content (BMC) of bilateral femoral necks, cortical area, cortical thickness, total volumetric bone mineral density (vBMD), and trabecular thickness were significantly correlated with 25(OH)Vit-D levels. In boys, aBMD of bilateral femoral necks, BMC of the dominant femoral neck, cortical area, cortical thickness, total vBMD, trabecular vBMD, BV/TV, and trabecular separation were significantly correlated with 25(OH)Vit-D levels. CONCLUSION: Vit-D insufficiency was highly prevalent among adolescents in Hong Kong with significant correlation between Vit-D levels and key bone density and bone quality parameters being detected in this study. Given that this is a cross-sectional study and causality relationship cannot be inferred, further interventional studies investigating the role of Vit-D supplementation on improving bone health among adolescents are warranted.

Molecular dynamics of anhydrous glycolipid self-assembly in lamellar and hexagonal phases.

The molecular dynamics of a synthetic branched chain glycolipid, 2-decyl-tetradecyl-ß-d-maltoside (C14-10G2), in the dry assemblage of smectic and columnar liquid crystal phases has been studied by dielectric spectroscopy as a function of frequency and temperature during the cooling process. Strong relaxation modes were observed corresponding to the tilted smectic and columnar phases, respectively. At low frequency (∼900 Hz to 1 kHz) in the smectic phase, Process I* was observed due to the tilted sugar bilayer structure. The process continued in the columnar phase (Process I) with an abrupt dynamic change due to phase transition in the frequency range of ∼1.3 kHz to 22 kHz. An additional process (Process II) was observed in the columnar phase with a broader relaxation in the frequency range of ∼10 Hz to 1 kHz. A bias field dependence study was performed in the columnar phase and we found that the relaxation strength rapidly decreased with increased applied dc bias field. This relaxation originates from a collective motion of polar groups within the columns. The results of dielectric spectroscopy were supported by a molecular dynamics simulation study to identify the origin of the relaxation processes, which could be related to the chirality and hydrogen bonds of the sugar lipid.

Phase sensitive molecular dynamics of self-assembly glycolipid thin films: a dielectric spectroscopy investigation.

Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assemble without the presence of a solvent. Here, the dielectric and conductivity properties of three synthetic glycolipid thin films in different thermotropic liquid crystal phases were investigated over a frequency and temperature range of (10(-2)-10(6) Hz) and (303-463 K), respectively. The observed relaxation processes distinguish between the different phases (smectic A, columnar/hexagonal, and bicontinuous cubic Q) and the glycolipid molecular structures. Large dielectric responses were observed in the columnar and bicontinuous cubic phases of the longer branched alkyl chain glycolipids. Glycolipids with the shortest branched alkyl chain experience the most restricted self-assembly dynamic process over the broad temperature range studied compared to the longer ones. A high frequency dielectric absorption (Process I) was observed in all samples. This is related to the dynamics of the hydrogen bond network from the sugar group. An additional low-frequency mechanism (Process II) with a large dielectric strength was observed due to the internal dynamics of the self-assembly organization. Phase sensitive domain heterogeneity in the bicontinuous cubic phase was related to the diffusion of charge carriers. The microscopic features of charge hopping were modelled using the random walk scheme, and two charge carrier hopping lengths were estimated for two glycolipid systems. For Process I, the hopping length is comparable to the hydrogen bond and is related to the dynamics of the hydrogen bond network. Additionally, that for Process II is comparable to the bilayer spacing, hence confirming that this low-frequency mechanism is associated with the internal dynamics within the phase.

Effect of whole body vibration (WBV) therapy on bone density and bone quality in osteopenic girls with adolescent idiopathic scoliosis: a randomized, controlled trial.

UNLABELLED: The aim of this randomized controlled trial was to determine whether whole body vibration (WBV) therapy was effective for treating osteopenia in adolescent idiopathic scoliosis (AIS) patients. Results showed that WBV was effective for improving areal bone mineral density (aBMD) at the femoral neck of the dominant side and lumbar spine BMC in AIS subjects. INTRODUCTION: AIS is associated with osteopenia. Although WBV was shown to have skeletal anabolic effects in animal studies, its effect on AIS subjects remained unknown. The objective of this study was to determine whether WBV could improve bone mineral density (BMD) and bone quality for osteopenia in AIS subjects. METHODS: This was a randomized, controlled trial recruiting 149 AIS girls between 15 and 25 years old and with bone mineral density (BMD) Z-scores <-1. They were randomly assigned to the Treatment or Control groups. The Treatment group (n = 61) stood on a low-magnitude high-frequency WBV platform 20 min/day, 5 days/week for 12 months. The Control group (n = 63) received observation alone. Bone measurement was done at baseline and at 12 months: (1) aBMD and BMC at femoral necks and lumbar spine using dual-energy X-ray absorptiometry (DXA) and (2) bone quality including bone morphometry, volumetric BMD (vBMD), and trabecular bone microarchitecture using high-resolution peripheral quantitative computed tomography (HR-pQCT) for nondominant distal radius and bilateral distal tibiae. RESULTS: The Treatment group had numerically greater increases in all DXA parameters with a statistically significant difference being detected for the absolute and percentage increases in femoral neck aBMD at the dominant leg (0.015 (SD = 0.031)g/cm(2), 2.15 (SD = 4.32)%) and the absolute increase in lumbar spine BMC (1.17 (SD = 2.05)g) in the Treatment group as compared with the Control group (0.00084 (SD = 0.026)g/cm(2), 0.13 (SD = 3.62)% and 0.47 (SD = 1.88)g, respectively). WBV had no significant effect for other bone quality parameters. CONCLUSIONS: WBV was effective for improving aBMD at the femoral neck of the dominant side and lumbar spine BMC in AIS subjects.

In-fiber common-path optical coherence tomography using a conical-tip fiber.

Common-path optical coherence tomography (CPOCT) is known to reduce group velocity dispersion and polarization mismatch between the reference and the sample arm as both arms share the same physical path. Existing implementations of CPOCT typically require one to incorporate an additional cover glass within the beam path of the sample arm to provide a reference signal. In this paper, we aim to further reduce this step by directly making use of the back-reflected signal, arising from a conical lens-tip fiber, as a reference signal. The conical lens, which is directly manufactured onto the optical fiber tip via a simple selective-chemical etching process, fulfils two functions acting as both the imaging lens and the self-aligning reference plane. We use a Fourier-domain OCT system to demonstrate the feasibility of this technique upon biological tissue. An in-fiber CPOCT technique may prove potentially useful in endoscopic OCT imaging.

Near-field focusing properties of zone plates in visible regime--new insights.

Near-field focusing properties of zone plates are investigated in the visible regime by a 3-dimensional finite-difference time-domain method. It is shown that Frensel zone plates (FZPs) with metallic coatings can achieve subwavelength focusing in the visible wavelength. The characteristics of subwavelength focusing are found to be independent of the type of metal coatings used. All the FZPs exhibit similar shift in focal length and depth of focus when compared with classical calculations. These results indicate that plasmonic waves do not contribute to subwavelength focusing. Instead the subwavelength focusing characteristic is attributed to the interference of diffracted evanescent waves from a large numerical aperture. It is found that the near-field focusing of FZPs suppresses higher order foci such that the corresponding diffraction efficiency is improved. The use of phase zone plate structured on glass without opaque coating is proposed to improve the diffraction efficiency of subwavelength focusing.

The effect of rigid versus flexible spinal orthosis on the gait pattern of patients with adolescent idiopathic scoliosis.

The conventional rigid spinal orthosis and the flexible spinal orthosis, SpineCor, have different treatment principles in the management of adolescent idiopathic scoliosis (AIS). These may influence the patients' gait pattern and clinical outcome. In this study, gait analysis on patients with AIS undergoing these two orthotic interventions were conducted. The patients' lower limb kinematic and kinetic data during level walking were collected using a motion analysis system and two force platforms in four test conditions: pre-intervention, having used the orthosis for 1 month and 1 year (in and out of the orthosis). Twenty-one subjects were randomly assigned to the rigid spinal orthosis group (10 subjects) and the SpineCor group (11 subjects). Neither group showed gait asymmetry when comparing the convex and concave sides in the four test conditions. However, significant reduction in the range of motion of the pelvis and hip joints in the coronal plane were found. Although patients with AIS undergoing these two orthotic interventions showed significant changes in walking pattern within the study period, their long-term effect on gait and function requires further investigation through long-term prospective studies.

Gonadal shield: is it the Albatross hanging around the neck of developmental dysplasia of the hip research?

PURPOSE: Prospective randomized controlled trials and long-term studies are essential future directions for building -evidence-based practices in developmental dysplasia of the hip (DDH), however, sufficient attrition in data (> 20%) can introduce bias deteriorating research quality. Pelvic radiography is synonymous with DDH assessment and so are -Gonadal Shield (GS) recommendations with pelvic radiography. -Nonetheless, losses to diagnostic information and inadequate protection have been increasingly implicated to GS usage, with significantly worse implications in female patients. Understandably for DDH, a disease with 80% female prevalence, the impact of GS usage on quality of radiographs and readability of radiological data may be drastic. This study aims to objectively define the implications of GS recommendations in DDH patients. METHODS: Pelvis radiographs of all DDH patients under the hip surveillance programme at a tertiary care hospital with a written protocol for GS usage were evaluated. Images were reviewed for gender, GS presence, adequate gonadal protection and obstruction of essential anatomical landmarks for pelvic indices. RESULTS: In all, 131 pelvis radiographs with DDH diagnoses (age: 1.25 to 6 years; 107 female, 24 male pelvises) were reviewed. Only 42.67% (56) of pelvis radiographs used GS despite the presence of a clear protocol. Useful anatomical landmarks were obstructed in 58.9% of radiographs with GS present. Lost diagnostic information was more common in female patients than male patients (68.1% versus 11.1%, p < 0.01). GS was ineffective at gonadal protection in 73.2% (41) of the pelvises with worse protection in female patients (78.7% vs 44.4%; p = 0.03). CONCLUSIONS: Ironically, essential anatomy was obstructed in all the adequately protected female pelvises. Routine GS usage results in substantial attrition of radiographic data in DDH patients. LEVEL OF EVIDENCE: III.

Altered White Matter Microstructure in the Corpus Callosum and Its Cerebral Interhemispheric Tracts in Adolescent Idiopathic Scoliosis: Diffusion Tensor Imaging Analysis.

BACKGROUND AND PURPOSE: Neural system was one of the important contributors to the etiopathogenesis of adolescent idiopathic scoliosis; additionally, the morphology of corpus callosum interconnecting both hemispheres of the brain was found to be altered morphologically. Our aim was to evaluate and compare the microstructural changes of the corpus callosum and its interhemispheric white matter fiber tracts interconnecting both cerebral hemispheres in patients with adolescent idiopathic scoliosis and matched controls using diffusion tensor imaging. MATERIALS AND METHODS: Brain DTI was performed in 69 patients with adolescent idiopathic scoliosis (female, right thoracic/thoracolumbar curve) and 40 age-matched controls without adolescent idiopathic scoliosis (female). 2D and 3D segmentation of the corpus callosum were performed using a region-growing method, and the corpus callosum was further divided into 6 regions, including the rostrum, genu, anterior and posterior midbodies, isthmus, and splenium. The laterality index was calculated to quantify the asymmetry of the corpus callosum. Interhemispheric fiber tractography were performed using the Brodmann atlas. RESULTS: 2D ROI analysis revealed reduced fractional anisotropy in the genu and splenium (P = .075 and P = .024, respectively). Consistently reduced fractional anisotropy on the left sides of the genu and splenium was also found in 3D ROI analysis (P = .03 and P = .012, respectively). The laterality index analysis revealed a pseudo-right lateralization of the corpus callosum in adolescent idiopathic scoliosis. Interhemispheric fibers via the splenium interconnecting Brodmann 3, 1, and 2; Brodmann 17; and Brodmann 18 (corresponding to the primary somatosensory cortex and primary and secondary visual cortices) were also found to have reduced fractional anisotropy (P ≤ .05). CONCLUSIONS: Reduced fractional anisotropy was found in the genu and splenium of the corpus callosum and corresponding interhemispheric fiber tracts interconnecting the somatosensory and visual cortices via the splenium. Our results are suggestive of altered white matter microstructure within the brain of those with adolescent idiopathic scoliosis, which could be related to abnormal brain maturation during adolescence in adolescent idiopathic scoliosis and could possibly explain the previously documented somatosensory function impairment and visuo-oculomotor dysfunction in this condition.

Progesterone synthesized by Schwann cells during myelin formation regulates neuronal gene expression.

Previously, progesterone was found to regulate the initiation and biosynthetic rate of myelin synthesis in Schwann cell/neuronal cocultures. The mRNA for cytochrome P450scc (converts cholesterol to pregnenolone), 3beta-hydroxysteroid dehydrogenase (3beta-HSD, converts pregnenolone to progesterone), and the progesterone receptor were found to be markedly induced during active myelin synthesis. However, the cells in the cocultures responsible for these changes were not identified. In this study, in situ hybridization was used to determine the localization of the enzymes responsible for steroid biosynthesis. The mRNA for cytochrome P450scc and 3beta-HSD were detected only in actively myelinating cocultures and were localized exclusively in the Schwann cells. Using immunocytochemistry, with minimal staining of the Schwann cells, we found the progesterone receptor in the dorsal root ganglia (DRG) neurons. The progesterone receptor in the neurons translocated into the nuclei of these cells when progesterone was added to neuronal cultures or during myelin synthesis in the cocultures. Additionally, a marked induction of the progesterone receptor was found in neuronal cultures after the addition of progesterone. The induction of various genes in the neurons was also investigated using mRNA differential display PCR in an attempt to elucidate the mechanism of steroid action on myelin synthesis. Two novel genes were induced in neuronal cultures by progesterone. These genes, along with the progesterone receptor, were also induced in cocultures during myelin synthesis, and their induction was blocked by RU-486 (a progesterone receptor antagonist). These genes were not induced in Schwann cells cultured alone after the addition of progesterone. These results suggest that progesterone is synthesized in Schwann cells and that it can indirectly regulate myelin formation by activating transcription via the classical steroid receptor in the DRG neurons.

Clinically applicable optical imaging technology for body size and shape analysis: comparison of systems differing in design.

BACKGROUND/OBJECTIVES: Recent advances have extended anthropometry beyond flexible tape measurements to automated three-dimensional optical devices that rapidly acquire hundreds of body surface dimensions. Three new devices were recently introduced that share in common inexpensive optical cameras. The design, and thus potential clinical applicability, of these systems differ substantially leading us to critically evaluate their accuracy and precision. SUBJECTS/METHODS: 113 adult subjects completed evaluations by the three optical devices (KX-16 (16 stationary cameras), Proscanner (1 vertically oscillating camera), and Styku scanner (1 stationary camera)), air displacement plethysmography (ADP), dual-energy X-ray absorptiometry (DXA) and a flexible tape measure. Optical measurements were compared to reference method estimates that included results acquired by flexible tape, DXA and ADP. RESULTS: Optical devices provided respective circumference and regional volume estimates that overall were well-correlated with those obtained from flexible tape measurements (for example, hip circumference: R2, 0.91, 0.90, 0.96 for the KX-16, Proscanner, and Styku scanner, respectively) and DXA (for example, trunk volume: R2, 0.97, 0.97, and 0.98). Total body volumes measured by the optical devices were highly correlated with those from the ADP system (all R2s, 0.99). Coefficient of variations obtained from duplicate measurements (n, 55) were larger in optical than in reference measurements and significant (P<0.05) bias was present for some optical measurements relative to reference method estimates. CONCLUSIONS: Overall, the evaluated optical imaging systems differing in design provided body surface measurements that compared favorably with corresponding reference methods. However, our evaluations uncovered system measurement limitations, such as discrepancies in landmarking, that with correction have the potential to improve future developed devices.

A comparison of the clinical effectiveness of spinal orthoses manufactured using the conventional manual method and CAD/CAM method in the management of AIS.

Spinal orthoses are commonly prescribed to patients with moderate AIS for prevention of further deterioration. In a conventional manufacturing method, plaster bandages are used to get patient's body contour and plaster cast is rectified manually. With the introduction of CAD/CAM system, a series of automated processes from body scanning to digital rectification and milling of positive model can be performed in a fast and accurate fashion. This project is to study the impact of CAD/CAM method as compared with the conventional method. In assessing the 147 recruited subjects fitted with spinal orthoses (43 subjects using conventional method and 104 subjects using CAD/CAM method), significant decreases (p<0.05) were found in the Cobb angles when comparing the pre-intervention data with that of the first year of intervention. Regarding the learning curve, Orthotists are getting more competent with the CAD/CAM technique in four years time. The mean productivity of the CAD/CAM method is 2.75 times higher than that of the conventional method. The CAD/CAM method could achieve similar clinical outcomes and with its high efficiency, could be considered as substitute for conventional methods in fabricating spinal orthoses for patients with AIS.

Genetic association study of insulin-like growth factor-I (IGF-I) gene with curve severity and osteopenia in adolescent idiopathic scoliosis.

UNLABELLED: IGF-I has a pivotal role in bone growth and could be one of the putative disease-modifier genes in AIS. Two SNPs in IGF-I gene promoter region were studied for any association with occurrence of AIS and for their effect on the curve severity among AIS. METHODS: 506 AIS girls (Cobb>20 degrees) and 227 age-matched Chinese girls were recruited. The spine (L2-L4) and hip BMD of the subjects were measured by DXA. A subgroup of AIS patients (N=340) who were followed-up to skeletal maturity and the maximum Cobb's angle was recorded. Two SNPs were genotyped by PCR-RFLP (rs5742612 and rs2288377). The chi-square test and one-way ANOVA were used to test the association between genotypes and quantitative parameters, respectively. RESULTS: No association was between the genotypes and the occurrence of AIS and the BMD of the spine and hip. The allelic frequency of T allele was 0.69 in AIS and control. However, the Cobb's angle was higher in patients with the homozygous T allele (Mean Cobb's angle: 38.1 degrees in TT vs 35.9 degrees in TC vs 33.2 degrees in CC group; p=0.04). DISCUSSION: Interestingly, IGF-I polymorphism affects the curve severity of AIS though it was not associated with onset of AIS per se. It indicates that IGF-I may be a disease modifying gene. The importance of IGF-I in skeletal growth makes it a good candidate gene which would play a role in the documented association of rapid growth with curve progression in AIS.

Persistent osteopenia in adolescent idiopathic scoliosis--longitudinal monitoring of bone mineral density until skeletal maturity.

The aim of this study was to monitor BMD changes occurring during periods of rapid growth and to investigate whether osteopenia was a persistent phenomenon in skeletally matured AIS girls. 196 AIS Chinese girls and 122 healthy controls, aged 11-16, were follow-up for 3.5 years. Bilateral femoral neck bone mineral density (BMD) and volumetric BMD (vBMD) of the distal tibia were obtained by dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Osteopenia was defined if the age-adjusted BMD was below or equal to -1 standard deviation (SD). The average age at the final follow-up was 16.8 years old. The median initial Cobb angle for this group of patients was 26 degrees. The prevalence of osteopenia at the baseline measurement was 35.9%. Longitudinal BMD results demonstrated that 86.0% of osteopenic AIS girls had persistently low BMD at the time of skeletal maturity (age of 16). vBMD of distal tibia of AIS was significantly lower than that of the controls throughout the age of 13 to 17 during the period of rapid growth. In addition, there were also significant differences in vBMD among AIS (moderate and severe group) and the controls by one-way ANOVA (p<0.05). The present study for the first time revealed that over 86% of osteopenic AIS patients had persistently low BMD, at both distal tibia and femoral neck regions, at the time of skeletal maturity. Early detection and treatment of AIS-related osteopenia might help in maximizing peak bone mass during peripubertal growth that thereby minimizing risks of developing osteoporotic fractures later in life.

Changes in vertebral neural arch morphometry and functional tethering of spinal cord in adolescent idiopathic scoliosis--study with multi-planar reformat magnetic resonance imaging.

With the use of multiplanar reformat Magnetic Resonance imaging, AIS patients were found to have significantly reduced pedicle widths on concavity. Pattern of vertebral asymmetry was also exaggerated with smaller pedicle width, length and area on concavity. The cord appeared more roundish and was deviated to the concavity at apical vertebra in AIS. A tethering force might therefore be present on the cord along the transverse axis in AIS, accounted by the relatively fixed position of the exit nerve roots and deviation of the cord from the exit foraminae of the corresponding vertebra.

Clinical anthropometrics and body composition from 3D whole-body surface scans.

BACKGROUND/OBJECTIVES: Obesity is a significant worldwide epidemic that necessitates accessible tools for robust body composition analysis. We investigated whether widely available 3D body surface scanners can provide clinically relevant direct anthropometrics (circumferences, areas and volumes) and body composition estimates (regional fat/lean masses). SUBJECTS/METHODS: Thirty-nine healthy adults stratified by age, sex and body mass index (BMI) underwent whole-body 3D scans, dual energy X-ray absorptiometry (DXA), air displacement plethysmography and tape measurements. Linear regressions were performed to assess agreement between 3D measurements and criterion methods. Linear models were derived to predict DXA body composition from 3D scan measurements. Thirty-seven external fitness center users underwent 3D scans and bioelectrical impedance analysis for model validation. RESULTS: 3D body scan measurements correlated strongly to criterion methods: waist circumference R2=0.95, hip circumference R2=0.92, surface area R2=0.97 and volume R2=0.99. However, systematic differences were observed for each measure due to discrepancies in landmark positioning. Predictive body composition equations showed strong agreement for whole body (fat mass R2=0.95, root mean square error (RMSE)=2.4 kg; fat-free mass R2=0.96, RMSE=2.2 kg) and arms, legs and trunk (R2=0.79-0.94, RMSE=0.5-1.7 kg). Visceral fat prediction showed moderate agreement (R2=0.75, RMSE=0.11 kg). CONCLUSIONS: 3D surface scanners offer precise and stable automated measurements of body shape and composition. Software updates may be needed to resolve measurement biases resulting from landmark positioning discrepancies. Further studies are justified to elucidate relationships between body shape, composition and metabolic health across sex, age, BMI and ethnicity groups, as well as in those with metabolic disorders.

Osteopenia: a new prognostic factor of curve progression in adolescent idiopathic scoliosis.

BACKGROUND: Studies have shown that 27% to 38% of girls with adolescent idiopathic scoliosis have systemic osteopenia. The aim of this study was to investigate whether osteopenia could serve as one of the important prognostic factors in predicting curve progression. METHODS: A prospective study was performed in 324 adolescent girls with adolescent idiopathic scoliosis who had a mean age of thirteen and a half years. Bone mineral density of the spine and both hips was measured at the time of the clinical diagnosis of scoliosis. All patients were followed longitudinally until skeletal maturity or until the curve had progressed > or =6 degrees . The univariate chi-square test and stepwise logistic regression were used to predict the prevalence of curve progression, and a receiver operating characteristic curve was plotted. RESULTS: The overall prevalence of curve progression was 50%. The prevalence of osteopenia at the spine and hips was 27.5% and 23.1%, respectively. A larger initial Cobb angle (odds ratio = 4.6), a lower Risser grade (odds ratio = 4.7), premenarchal status (odds ratio = 2.5), osteopenia in the femoral neck of the hip on the side of the concavity (odds ratio = 2.3), and a younger age at the time of diagnosis (odds ratio = 2.1) were identified as risk factors in predicting curve progression. A predictive model was established, and the area under the receiver operating characteristic curve of the model was 0.80 (p < 0.01). CONCLUSION: Osteopenia may be an important risk factor in curve progression. The measurement of bone mineral density at the time of diagnosis may serve as an additional objective measurement in predicting curve progression in adolescent idiopathic scoliosis. The bone mineral density-inclusive predictive model may be used in treatment planning for patients with adolescent idiopathic scoliosis who are at high risk of curve progression.

Bone mineralization at the callotasis site after completion of lengthening.

We studied the course of bone mineralization of regenerate bone after callotasis lengthening. Twenty-three patients (eight boys) (mean age at operation 11.5 years, range 4-17 years; leg length discrepancy [LLD] at surgery ranging from 4 to 13 cm) underwent dual-energy X-ray absorptiometry (DEXA) scanning weekly during the distraction phase, at 2 week intervals until removal of the fixator, and at the time of their out-patient visits thereafter, for a mean of 794 +/- 420 days after removal of the apparatus. At removal of the fixator, the bone mineral content (BMC) of the regenerate was nearly 70% of the normal contralateral limb. With time, this value gradually increased, and tended to reach normal values, with no significant difference between femur and tibia. With time, the BMC of the regenerate tends to return to the value of the normal contralateral limb. Probably, once the limb length discrepancy has been equalized, the mechanical stimuli imparted through weight-bearing to the lengthened limb are of the same magnitude bilaterally. In this instance, then, the newly formed bone, responding to these physical stimuli, would normalize its mineral content, confirming that bone remodeling continues well after lengthening is terminated. Mineralization of the regenerate after completion of the lengthening process reaches values significantly greater than at removal of the fixator, with an increase of >50% of the prelengthening values, regardless of the underlying pathology. The final value of this increased BMC is not significantly different than in the normal contralateral unoperated limb. At least part of the increase in bone mineralization following callotasis lengthening is due to the normal process of growth and development.