Objectives: To evaluate axial cervical vertebral (ACV) shape quantitatively and to build a prediction model for skeletal maturation level using statistical shape analysis for Japanese individuals. Methods: The sample included 24 female and 19 male patients with hand-wrist radiographs and CBCT images. Through generalized Procrustes analysis and principal components (PCs) analysis, the meaningful PCs were extracted from each ACV shape and analysed for the estimation regression model. Results: Each ACV shape had meaningful PCs, except for the second axial cervical vertebra. Based on these models, the smallest prediction intervals (PIs) were from the combination of the shape space PCs, age and gender. Overall, the PIs of the male group were smaller than those of the female group. There was no significant correlation between centroid size as a size factor and skeletal maturation level. Conclusions: Our findings suggest that the ACV maturation method, which was applied by statistical shape analysis, could confirm information about skeletal maturation in Japanese individuals as an available quantifier of skeletal maturation and could be as useful a quantitative method as the skeletal maturation index.

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A caudal epidural block involves placing a needle through the sacral hiatus and delivering medication into the epidural space. The procedure is safe and simple, but failure rates can be as high as 25%. The purpose of this study was to investigate the success rate of caudal epidural block by analyzing needle placement and dye flow pattern.We retrospectively analyzed the medical records of patients who underwent caudal epidural block under spinal stenosis. A case was defined as a failure if it met at least one of the following four criteria: the epidural needle was not placed correctly inside the caudal canal; blood regurgitation or aspiration in the needle was observed; the contrast dye was injected into a blood vessel; or a large amount of the dye leaked into the sacral foramen or did not reach the L5-S1 level.At least 1 failure criterion was observed in 14 cases (17.7%), while none of the failure criteria were satisfied in 65 successful cases (82.3%).No matter how experienced the anesthesiologist may be, delivery of adequate therapeutic agent is not achieved in approximately 20% of cases. Therefore, we recommend fluoroscopy-guided needle placement and confirmation by radio-contrast epidurograpy as the best choice.