The objective of this study was to determine the prevalence of flexible flatfoot in elementary school children in Taiwan and evaluate the relationship between flatfoot and obesity, gender, and age. A sample of 2,083 children, between 7 and 12 years of age from public elementary schools in northern Taiwan was analyzed. Children were stratified into groups according to age: 7, 8, 9, 10, 11, or 12 years old. Demographic information was obtained, and the presence of flatfoot determined by footprint analysis and grading according to Denis flatfoot staging. A total of 1,222 (59%) children were documented with flatfoot. The incidence percentages of flatfoot were: 67% of males, 49% of females, and 75%, 65%, 57%, and 48% of obese, overweight, normal weight, and underweight children, respectively. A preponderance of flatfoot was observed among 8-year-olds. Multivariate analyses indicated that 8- and 9-year-olds were 1.52 and 0.72 times more likely to have flatfoot than 7-year-olds. Males were twice as likely to have flatfoot as females. Children who were obese or overweight were 2.66 and 1.39 times more likely to have flatfoot than those of average weight. The results of this study indicate that the prevalence of flexible flatfoot is highest among males who are obese and overweight, particularly in the age range of 7 to 8 years.

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IntroductionThe aim of this study was to evaluate, for the first time, the differences in gene expression profiles of normal and osteoarthritic (OA) subchondral bone in human subjects.MethodsFollowing histological assessment of the integrity of overlying cartilage and the severity of bone abnormality by micro-computed tomography, we isolated total RNA from regions of interest from human OA (n = 20) and non-OA (n = 5) knee lateral tibial (LT) and medial tibial (MT) plateaus. A whole-genome profiling study was performed on an Agilent microarray platform and analyzed using Agilent GeneSpring GX11.5. Confirmatory quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis was performed on samples from 9 OA individuals to confirm differential expression of 85 genes identified by microarray. Ingenuity Pathway Analysis (IPA) was used to investigate canonical pathways and immunohistochemical staining was performed to validate protein expression levels in samples.ResultsA total of 972 differentially expressed genes were identified (fold change ≥ ± 2, P ≤0.05) between LT (minimal degeneration) and MT (significant degeneration) regions from OA samples; these data implicated 279 canonical pathways in IPA. The qRT-PCR data strongly confirmed the accuracy of microarray results (R2 = 0.58, P <0.0001). Novel pathways were identified in this study including Periostin (POSTN) and Leptin (LEP), which are implicated in bone remodeling by osteoblasts.ConclusionsTo the best of our knowledge, this study represents the most comprehensive direct assessment to date of gene expression profiling in OA subchondral bone. This study provides insights that could contribute to the development of new biomarkers and therapeutic strategies for OA.