Axial and frontal X-ray fluoroscopy technique of the sustentaculum tali can improve the accuracy of sustentacular screw placement.

INTRODUCTION: Calcaneal fractures, especially those involving the articular surface, should be anatomically reduced as much as possible. Fixing the fracture by placing a screw into the sustentaculum tali from the lateral side of the calcaneus is generally considered to be the key to successful surgery. However, due to the limited visibility during surgery, it is not easy to place screws into the sustentaculum tali accurately. The purpose of this study was to explore a new fluoroscopy method for the sustentaculum tali and verify the value of this method in improving screw placement accuracy. METHODS: In this study, a total of 42 human foot and ankle specimens were dissected and measured. The shape and position of the sustentaculum tali were observed, and the influence of adjacent bones on imaging findings was analysed. The axial and frontal X-ray fluoroscopy method to view the sustentaculum tali was formulated, and the appropriate projection angle through anatomical and image measurements was explored. Thirty specimens were randomly selected for screw placement, and the direction of the screw was dynamically adjusted under the new imaging method. The success rate of sustentacular screw placement was evaluated. RESULTS: The anteversion angles of the sustentaculum tali were 30.81 ± 2.21° and 30.68 ± 2.86° by anatomical and imaging measurements, respectively. There was no statistically significant difference in the anteversion angle between the two measurement methods. Harris heel views should be obtained at 30° to identify the sustentaculum tali on axial X-ray images. Frontal X-ray imaging was performed perpendicular to this projection angle. Through frontal and axial X-ray imaging, the position and shape of the sustentaculum tali can be clearly observed, and these factors are seldom affected by adjacent bones. Under the new fluoroscopy method, the screws were placed from the anterior region of the lateral wall of the calcaneus to the sustentaculum tali. A total of 60 screws were placed in the 30 specimens; of these, 54 screws were in good position, 2 screws penetrated the cortical bone, and 4 screws did not enter the sustentaculum tali. The success rate of sustentacular screw placement was 90% (54/60). CONCLUSIONS: Axial and frontal X-ray images of the sustentaculum tali can clearly show the shape of the structure, which improves sustentacular screw placement accuracy.

Changes in the gut microbiota during and after commercial helium-oxygen saturation diving in China.

OBJECTIVES: The influence of commercial helium-oxygen saturation diving on divers' gut microbiotas was assessed to provide dietary suggestion. METHODS: Faecal samples of 47 divers working offshore were collected before (T1), during (T2) and after (T3) saturation diving. Their living and excursion depths were 55-134 metres underwater with a saturation duration of 12-31 days and PaO2 of 38-65 kPa. The faecal samples were examined through 16S ribosomal DNA amplicon sequencing based on the Illumina sequencing platform to analyse changes in the bacteria composition in the divers' guts. RESULTS: Although the α and ß diversity of the gut microbiota did not change significantly, we found that living in a hyperbaric environment of helium-oxygen saturation decreased the abundance of the genus Bifidobacterium, an obligate anaerobe, from 2.43%±3.83% at T1 to 0.79%±1.23% at T2 and 0.59%±0.79% at T3. Additionally, the abundance of some short-chain fatty acid (SCFA)-producing bacteria, such as Fusicatenibacter, Faecalibacterium, rectale group and Anaerostipes, showed a decreased trend in the order of before, during and after diving. On the contrary, the abundance of species, such as Lactococcus garvieae, Actinomyces odontolyticus, Peptoclostridium difficile, Butyricimonas virosa, Streptococcus mutans, Porphyromonas asaccharolytica and A. graevenitzii, showed an increasing trend, but most of them were pathogens. CONCLUSIONS: Occupational exposure to high pressure in a helium-oxygen saturation environment decreased the abundance of Bifidobacterium and some SCFA-producing bacteria, and increased the risk of pathogenic bacterial infection. Supplementation of the diver diet with probiotics or prebiotics during saturation diving might prevent these undesirable changes.

Three-dimensional printing technique aids screw insertion into the sustentaculum tali of the internal fixation of intra-articular calcaneal fractures.

INTRODUCTION: Treating complex calcaneus fractures remains challenging. This study evaluated the influence of 3D printing and simulation on precision screw insertion into the calcaneus sustentaculum tali (ST). HYPOTHESIS: 3D printing and simulation improve the treatment for calcaneal fracture. PATIENTS AND METHODS: This retrospective cohort study included 85 patients admitted with 93 Sanders type II-IV intra-articular fractures from January 2015 to June 2020. Multi-slice computed tomography (MSCT) images were used in the conventional group, and MSCT data were used to construct a 3D model of the calcaneus to simulate screw insertion and verify parameter accuracy in the 3D group. RESULTS: The designed parameters (upward and backward oblique angles and screw-path length) were similar to the actual values in the 3D group (p=0.428,0.287,0.585) but not in the conventional group (p=0.01,0.002,0.023). The Maryland foot functional score, accuracy rate, and average screw number were higher and operative time was shorter in the 3D group (p=0.005,0.007,0.000,0.000). DISCUSSION: Preoperative simulation using the 3D printing model helped guide the screws into the ST more accurately, lending better-quality treatment for Sanders type II-IV calcaneal fractures. LEVEL OF PROOF: III; Retrospective case-control study.

Conductance quantization in a Ag filament-based polymer resistive memory.

Resistive switching and conductance quantization are systematically studied in a Ag/poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester/indium-tin oxide sandwich structure. The observed bipolar switching behavior can be attributed to the formation and dissolution of Ag filaments during positive and negative voltage sweeps, respectively. More importantly, conductance quantization with both integer and half integer multiples of single atomic point contact can be realized by slowing down the voltage sweep speed as well as by pulse measurement. The former may reflect the formed Ag filaments with different atomic point contacts, while the latter probably originates from the interaction between the Ag filaments and the elemental hydrogen provided by the organic storage medium. With appropriate current compliances, low resistance states with desired quantized conductance values are successfully achieved, thus showing the potential for ultrahigh density memory applications. Besides, 100 successive switching cycles with densely distributed resistance values of each resistance state and extrapolated retention properties over ten years are also demonstrated.

Effect of electrode materials on AlN-based bipolar and complementary resistive switching.

We report the complementary resistive switching (CRS) behaviors in aluminum nitride (AlN)-based memory devices as the promising new material system for large-scale integration of passive crossbar arrays. By utilizing different electrodes (Cu, Pt, and TiN), CRS characteristics are demonstrated in both TiN/AlN/Cu/AlN/TiN electrochemical metallization cells and Pt/AlN/TiN/AlN/Pt ionic resistive switching systems. The instability of Pt/AlN/Cu/AlN/Pt based CRS is explained by the relatively small reset voltage caused by the thermal effects enhanced reset process in the corresponding bipolar resistive switching element. It is concluded that the prerequisite for reliable and stable CRS is that the reset voltage of the bipolar resistive switching element must be much larger than half of the set voltage.

Programmable complementary resistive switching behaviours of a plasma-oxidised titanium oxide nanolayer.

Through the one-step plasma oxidation of TiN thin films at room temperature (a simple semiconductor technology compatible method), a partly oxidised structure of titanium oxynitride (TiN(x)O(y)) with a TiO(2-x) nanolayer on top has been prepared for non-volatile resistive switching memory devices. The fabricated Pt/TiO(2-x)/TiN(x)O(y)/TiN memory devices demonstrate complementary resistive switching behaviours within an operation voltage of 1 V. The complementary resistive switching behaviours can be explained by redistribution of the oxygen vacancies between the Pt/TiO(2-x) top interface and the TiO(2-x)/TiN(x)O(y) bottom interface in the TiO(2-x) nanolayer. A model concerning the resistive switching mechanism as well as a recover program of a failed device is also proposed. Our work provides a possible cost-efficient solution to suppress the sneak-path problem in nanoscale crossbar memory arrays.