Sustentaculum tali in Chinese population: anatomy and clinical significance.

BACKGROUND: Previous studies lacked adequate quantitative data on sustentaculum tali (ST), especially in Chinese population. The aims of this study are to explore the quantitative morphology of ST in dried bone specimens, and to discuss its implications related to ST screw fixation, talar articular facet variation, as well as subtalar coalitions. METHODS: A total of 965 dried intact calcanei from Chinese adult donors were evaluated. All linear parameters were measured by two observers with a digital sliding vernier caliper. RESULTS: Most parts of ST body can accommodate a commonly-used 4-mm-diameter screw, but the minimum height of anterior ST is only 4.02 mm. The shapes of the STs are slightly affected by left-right, subtalar facet, but the subtalar coalition may potentially increase the sizes of STs. The incidence of tarsal coalition is 14.09%. Among the osseous connection, there are 58.8% of type A articular surface and 76.5% of middle and posterior talar facet (MTF and PTF) involvement. ROC curve shows that subtalar coalition will be detected when ST length is greater than 16.815 mm. CONCLUSIONS: Theoretically, all the STs can accommodate 4 mm diameter screw, but a 3.5 mm diameter screw is recommended to be placed in the middle or posterior of the small ST for safety. The shapes of the STs are greatly influenced by the subtalar coalition, while they are less affected by left-right, subtalar facet. The osseous connection is common in type A articular surface and always involved in the MTF and PTF. The cut-off value of the length of STs was confirmed as 16.815 mm for predicting subtalar coalition.

Anatomical observation, classification, fracture and finite element analysis of the posterior process of the Asian adult talus.

BACKGROUND: Fractures of the posterior process of the talus are rarely seen and frequently overlooked. In our study, anatomical observation and classification of the posterior process of the talus were carried out, and related imaging and finite element methods were combined. The study aimed to observe and provide anatomical data related to posterior process of talus in Asian adults and explore the potential relationships between the different types with fracture of posterior process of talus. METHODS: Combined with the anatomical morphology and imaging data, the posterior process of talus was divided into four types, and the incidence and fracture situation were statistically analyzed. The finite element models of four different types of talus processes were established and verified, and the stress and strain were simulated and analyzed. RESULTS: The total incidence of the posterior process of the talus was 97.47%. The proportions of the four types were neck-like 10.13%, flat 36.29%, pointy 12.66% and round blunt 38.39%. The overall incidence of bone cracks of the posterior process of the talus was 4.98%; the most common type was neck-like type. Compared with the value on the other types, the maximum von Mises stress increased by 67.66%, 83.90% and 111.18% on the neck-like posterior process of talus respectively. CONCLUSIONS: It is speculated that different types of the posterior process of the talus may be related to the probability of fracture, and it may be better to consider different treatment strategies for different types of fractures.

Anatomical parameters of sustentaculum Tali screw placement in the Asian population: A retrospective radio-anatomical study.

Purpose: This study aimed to determine the anatomical parameters of successful Sustentaculum Tali (ST) screw placement in the Asian population. Method: CT scans of unilateral feet of 110 participants were reviewed, retrospectively. The 3 D reconstruction of the calcaneus and morphometric measurements were performed by Mimics Research 19.0 and 3-Matic Research 11.0. Finally, six cadaveric feet were used for verification of the accuracy of the measurements. Results: We discovered a method to help place ST screw successfully: (1) The entry point located at the middle section of the lateral wall of posterior talar articular surface (PTAS), and the perpendicular distance from the entry point to the lateral edge of PTAS (PDEL) was 10.78 mm, (2) Screw was perpendicular to the z-axis, 66.98° to the y-axis (the longitudinal axis of the foot), (3) The length of the ST screw should be approximately 44.74 mm in male and 41.14 mm in female, and (4) The diameter of the ST screw should be approximately 4.0 mm in male and 3.5 mm in female. With this new method, all screws in six cadaveric feet were placed successfully into the middle of ST. Conclusions: In this study, we discovered a general approach to safely place ST screws in the Asian population, which may potentially help surgeons improve their success rate in surgical practice.

Melatonin Accelerates Osteoporotic Bone Defect Repair by Promoting Osteogenesis-Angiogenesis Coupling.

Previous studies have revealed that melatonin could play a role in anti-osteoporosis and promoting osteogenesis. However, the effects of melatonin treatment on osteoporotic bone defect and the mechanism underlying the effects of melatonin on angiogenesis are still unclear. Our study was aimed to investigate the potential effects of melatonin on angiogenesis and osteoporotic bone defect. Bone marrow mesenchymal stem cells (BMSCs) were isolated from the femur and tibia of rats. The BMSC osteogenic ability was assessed using alkaline phosphatase (ALP) staining, alizarin red S staining, qRT-PCR, western blot, and immunofluorescence. BMSC-mediated angiogenic potentials were determined using qRT-PCR, western blot, enzyme-linked immunosorbent assay, immunofluorescence, scratch wound assay, transwell migration assay, and tube formation assay. Ovariectomized (OVX) rats with tibia defect were used to establish an osteoporotic bone defect model and then treated with melatonin. The effects of melatonin treatment on osteoporotic bone defect in OVX rats were analyzed using micro-CT, histology, sequential fluorescent labeling, and biomechanical test. Our study showed that melatonin promoted both osteogenesis and angiogenesis in vitro. BMSCs treated with melatonin indicated higher expression levels of osteogenesis-related markers [ALP, osteocalcin (OCN), runt-related transcription factor 2, and osterix] and angiogenesis-related markers [vascular endothelial growth factor (VEGF), angiopoietin-2, and angiopoietin-4] compared to the untreated group. Significantly, melatonin was not able to facilitate human umbilical vein endothelial cell angiogenesis directly, but it possessed the ability to promote BMSC-mediated angiogenesis by upregulating the VEGF levels. In addition, we further found that melatonin treatment increased bone mineralization and formation around the tibia defect in OVX rats compared with the control group. Immunohistochemical staining indicated higher expression levels of osteogenesis-related marker (OCN) and angiogenesis-related markers (VEGF and CD31) in the melatonin-treated OVX rats. Then, it showed that melatonin treatment also increased the bone strength of tibia defect in OVX rats, with increased ultimate load and stiffness, as performed by three-point bending test. In conclusion, our study demonstrated that melatonin could promote BMSC-mediated angiogenesis and promote osteogenesis-angiogenesis coupling. We further found that melatonin could accelerate osteoporotic bone repair by promoting osteogenesis and angiogenesis in OVX rats. These findings may provide evidence for the potential application of melatonin in osteoporotic bone defect.

Design and implementation of finite time sliding mode controller for fuzzy overhead crane system.

This paper considers the problem of fuzzy overhead crane system modelling and finite-time stability/boundedness via sliding mode control (SMC) method. Due to the strong coupling of control input, the fuzzy technique is utilized to linearize the overhead crane system and a fuzzy overhead crane model is established with appropriate membership functions. Considering the bad effect, including the swing of hook and plates, the external disturbances of the friction and air resistances, is inevitable during the transportation of copper electrode plates, the SMC method is adopted to stabilize the fuzzy system and robust to these interference signals. Furthermore, taking the time cost of actual industry into account, the finite-time stability/boundedness is introduced to achieve the state of system could be stable in a specified finite time. Moreover, the reaching law of sliding mode dynamics is analysed and the sufficient conditions for finite-time stability/boundedness of system state are formulated, respectively. Finally, the simulation results of the control strategy put forward in this article with the comparisons on some existing algorithms are provided to verify the effectiveness of the control strategy in the copper electrolytic overhead crane system.

A finite element analysis of sacroiliac joint displacements and ligament strains in response to three manipulations.

BACKGROUND: Clinical studies have found that manipulations have a good clinical effect on sacroiliac joint (SIJ) pain without specific causes. However, the specific mechanisms underlying the effect of manipulations are still unclear. The purpose of this study was to investigate the effects of three common manipulations on the stresses and displacements of the normal SIJ and the strains of the surrounding ligaments. METHODS: A three-dimensional finite element model of the pelvis-femur was developed. The manipulations of hip and knee flexion (MHKF), oblique pulling (MOP), and lower limb hyperextension (MLLH) were simulated. The stresses and displacements of the SIJ and the strains of the surrounding ligaments were analyzed during the three manipulations. RESULTS: MOP produced the highest stress on the left SIJ, at 6.6 MPa, while MHKF produced the lowest stress on the right SIJ, at 1.5 MPa. The displacements of the SIJ were all less than 1 mm during the three manipulations. The three manipulations caused different degrees of ligament strain around the SIJ, and MOP produced the greatest straining of the ligaments. CONCLUSION: The three manipulations all produced small displacements of the SIJ and different degrees of ligament strains, which might be the mechanism through which they relieve SIJ pain. MOP produced the largest displacement and the greatest ligament strains.

Effect of Multi-Source Ultrasonic on Segregation of Cu Elements in Large Al-Cu Alloy Cast Ingot.

The structure and composition of large-scale Al-Cu alloy ingots are inhomogeneous, and the segregation of (especially) elemental Cu negatively affects the uniformity and stability of the subsequent components. In this work, four ultrasonic generators were used to manipulate solidification/microstructures of cylindrical Al-Cu ingots (1250 mm in diameter; 3500 mm in length). The influence of ultrasonic configuration on both solidification microstructures and solute macrosegregation was investigated by changing the position parameters of generators for a fixed power. The results revealed that when the ultrasound is applied close to the center (I) from the 1/2 radius (II), the grain structure of the center undergoes significant refinement, degree of positive segregation in the center can be reduced, segregation index decreased from 0.2 to 0.15, and range of positive segregation in the center decreased from 200 to 150 mm. The segregation of elemental Cu was weakened by the combined effects of the ultrasound on the flow, heat transfer, and grain movement.

Morphological Characteristics of the Spinous Process of Axis: Clinical Implications for Cervical Spine Manipulation.

OBJECTIVE: The purpose of this study was to evaluate the osseous variation of the axis spinous process as it may relate to palpation by clinicians. METHODS: Morphologies of the bifid spinous process in the intact dry axis of 121 Chinese adult were investigated and classified. The angular deflection of the spinous processes, the bifid spinous processes (the bifid portions of the spinous processes), and the length of the bifid spinous processes were observed and measured. RESULTS: The bifid spinous process morphologies were classified into 4 types: inverted-V shape (n = 49), inverted-U shape (n = 50), M shape (n = 18), and nonbifid spinous processes (n = 4). The direction of the spinous processes and bifid spinous processes were consistent because they depended on each other's direction of deviation. When the correlation between angular deflection of spinous processes and bifid spinous processes was analyzed, the right deviations of spinous process specimens (29 cases) showed that angular deflections of spinous processes were equal to bifid spinous processes and there was no statistically significant difference seen between them (t = 0.286, P > .05), whereas in the left deviations of spinous process specimens (49 cases), the angular deflection of spinous processes were not equal in length, but bigger than the bifid spinous processes, which was statistically significant (t = -3.079, P = .003 < .05). CONCLUSION: The anatomical structure of the spinous processes and the bifid spinous processes vary from one another, but they exhibit some regularity. In clinical spinal manipulation practice, the anatomical characteristic of the axis should be taken into account during cervical static palpation, diagnostic imaging, and treatment.