Detecting the exponential relaxation spectrum in glasses by high-precision nanocalorimetry.

Nonexponential relaxations are universal characteristics for glassy materials. There is a well-known hypothesis that nonexponential relaxation peaks are composed of a series of exponential events, which have not been verified. In this Letter, we discover the exponential relaxation events during the recovery process using a high-precision nanocalorimetry, which are universal for metallic glasses and organic glasses. The relaxation peaks can be well fitted by the exponential Debye function with a single activation energy. The activation energy covers a broad range from α relaxation to ß relaxation and even the fast γ/ß' relaxation. We obtain the complete spectrum of the exponential relaxation peaks over a wide temperature range from 0.63Tg to 1.03Tg, which provides solid evidence that nonexponential relaxation peaks can be decomposed into exponential relaxation units. Furthermore, the contribution of different relaxation modes in the nonequilibrium enthalpy space is measured. These results open a door for developing the thermodynamics of nonequilibrium physics and for precisely modulating the properties of glasses by controlling the relaxation modes.

Size Dependent Phase Transformation of Liquid Gallium.

As the most popular liquid metal (LM), gallium (Ga) and its alloys are emerging as functional materials due to their unique combination of fluidic and metallic properties near room temperature. As an important branch of utilizing LMs, micro- and submicron-particles of Ga-based LM are widely employed in wearable electronics, catalysis, energy, and biomedicine. Meanwhile, the phase transition is crucial not only for the applications based on this reversible transformation process, but also for the solidification temperature at which fluid properties are lost. While Ga has several solid phases and exhibits unusual size-dependent phase behavior. This complex process makes the phase transition and undercooling of Ga uncontrollable, which considerably affects the application performance. In this work, extensive (nano-)calorimetry experiments are performed to investigate the polymorph selection mechanism during liquid Ga crystallization. It is surprisingly found that the crystallization temperature and crystallization pathway to either α -Ga or ß -Ga can be effectively engineered by thermal treatment and droplet size. The polymorph selection process is suggested to be highly relevant to the capability of forming covalent bonds in the equilibrium supercooled liquid. The observation of two different crystallization pathways depending on the annealing temperature may indicate that there exist two different liquid phases in Ga.

Activation Entropy as a Key Factor Controlling the Memory Effect in Glasses.

As opposed to the common monotonic relaxation process of glasses, the Kovacs memory effect describes an isothermal annealing experiment, in which the enthalpy and volume of a preannealed glass first increases before finally decreasing toward equilibrium. This interesting behavior has been observed for many materials and is generally explained in terms of heterogeneous dynamics. In this Letter, the memory effect in a model Au-based metallic glass is studied using a high-precision high-rate calorimeter. The activation entropy (S^{*}) during isothermal annealing is determined according to the absolute reaction rate theory. We observe that the memory effect appears only when the second-annealing process has a large S^{*}. These results indicate that a large value of S^{*} is a key requirement for observation of the memory effect and this may provide a useful perspective for understanding the memory effect in both thermal and athermal systems.

Circ-SATB2 upregulates STIM1 expression and regulates vascular smooth muscle cell proliferation and differentiation through miR-939.

The prevention and treatment of coronary heart disease (CHD) is a difficult problem to be solved. More and more studies have found that circular RNAs (circRNAs) may play important roles in the development of CHD. Here detection of vascular smooth muscle cells (VSMCs) showed that circ-SATB2 and STIM1 were up-regulated in proliferative VSMCs, while miR-939 were down-regulated. Circ-SATB2 and miR-939 did not affect the expression of each other, but circ-SATB2 could promote while miR-939 inhibited the expression of STIM1 (a target gene of miR-939). Circ-SATB2 overexpression could inhibit the expression of SM22-alpha (SM22α, a marker of contractile VSMCs), while the expression of SM22α was promoted by miR-939. STIM1 could promote cell proliferation and migration, and circ-SATB2 had similar effects, but its linear sequence had no such functions. MiR-939 had the opposite effects, could promote cell apoptosis and inhibit cell proliferation and migration, and siRNAs targeting circ-SATB2 had similar effects. When co-transfected with circ-SATB2 over-expression vector and miR-939 mimics or STIM1 siRNAs, the changes of cell proliferation, apoptosis and migration were not significant. Therefore, circ-SATB2 can regulate VSMC phenotypic differentiation, proliferation, apoptosis and migration by promoting the expression of STIM1. This discovery will provide a theoretical reference for exploring the role of circRNA in VSMCs and the pathogenesis of CHD.

Nucleation of shear bands in amorphous alloys.

The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load-depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys.

Possible existence of two amorphous phases of D-mannitol related by a first-order transition.

We report that the common polyalcohol D-mannitol may have two amorphous phases related by a first-order transition. Slightly above its glass transition temperature Tg (284 K), the supercooled liquid (SCL) of D-mannitol transforms to a low-energy, apparently amorphous phase with stronger hydrogen bonds. The enthalpy of this so-called Phase X is approximately halfway between those of the known amorphous and crystalline phases, a position low for glass aging and high for crystal polymorphs. Similar to the SCL, Phase X is transparent with broad X-ray diffraction and Raman scattering; upon temperature cycling, it exhibits a glass-transition-like change of heat capacity. On fast heating, Phase X transforms back to the SCL near Tg + 50 K, enabling a determination of their equilibrium temperature. The presence of D-sorbitol as a plasticizer enables observation of a first-order transition from the SCL to Phase X entirely in the liquid state (liquid-liquid transition). The transition from D-mannitol's SCL to Phase X has intriguing similarities with the formation of the glacial phase of triphenyl phosphite (TPP) and the conversion from high-density to low-density amorphous ice, both studied intensely in the context of polyamorphism. All three processes occur near Tg with substantial enthalpy decrease toward the crystalline phases; the processes in water and D-mannitol both strengthen the hydrogen bonds. In contrast to TPP, D-mannitol's Phase X forms more rapidly and can transform back to the SCL. These features make D-mannitol a valuable new model for understanding polyamorphism.

Designing Advanced Amorphous/Nanocrystalline Alloys by Controlling the Energy State.

Amorphous alloys, also known as metallic glasses, exhibit many advanced mechanical, physical, and chemical properties. Owing to the nonequilibrium nature, their energy states can vary over a wide range. However, the energy relaxation kinetics are very complex and composed of various types that are coupled with each other. This makes it challenging to control the energy state precisely and to study the energy-properties relationship. This brief review introduces the recent progresses on studying the enthalpy relaxation kinetics during isothermal annealing, for example, the observation of two-step relaxation phenomenon, the detection of relaxation unit (relaxun), the key role of large activation entropy in triggering memory effect, the influence of glass energy state on nanocrystallization. Based on the above knowledge, a new strategy is proposed to design a series of amorphous alloys and their composites consisting of nanocrystals and glass matrix with superior functional properties by precisely controlling the nonequilibrium energy states. As the typical examples, Fe-based amorphous alloys with both advanced soft magnetism and good plasticity, Gd-based amorphous/nanocrystalline composites with large magnetocaloric effect, and Fe-based amorphous alloys with high catalytic performance are specifically described.

[Orthopaedic robot assisted femoral neck dynamic cross fixation system for the treatment of femoral neck fractures].

OBJECTIVE: To explore and compare the clinical efficacy of orthopedic robot assisted femoral neck system （FNS） and traditional manual FNS in the treatment of femoral neck fractures in middle-aged and young people. METHODS: The clinical data of 62 consecutive patients with femoral neck fracture and age less than 65 years old admitted to the Intelligent Orthopaedic Department of Beijing Jishuitan Hospital from June 2021 to June 2022 were retrospectively analyzed. According to whether orthopedic robot-assisted surgery the patients were divided into two groups：30 patients aged 34 to 56 years old were treated with orthopedic robot assisted FNS internal fixation after closed or limited open reduction（experimental group）； 32 patients aged 33 to 54 years old underwent FNS internal fixation after closed or limited open reduction（control group）. The age, gender, time from injury to admission, average hospital stay, surgical duration, intraoperative bleeding volume, and intraoperative fluoroscopy frequency of two groups of patients were analyzed and compared. The hip joint function in both groups of patients was evaluated using the Harris hip joint scoring standard at 6 months after surgery. RESULTS: All 62 patients with femoral neck fractures successfully completed the surgery. There was no significant difference（P>0.05） between the experimental group and the control group in terms of baseline data such as age, gender, time from injury to admission, time from admission to surgery and the intraoperative bleeding. The surgical duration of the experimental group was significantly shorter than that of the control group [42.1（28.5, 50.7）min vs. 53.4（36.9, 62.5） min, Z=-2.338, P=0.019]. The intraoperative X-ray fluoroscopy frequency of the experimental group was significantly lower than that of the control group[8.0 （6.0, 11.0） times vs. 15.0（13.0, 17.0） times, Z=-5.960, P<0.001]. In terms of postoperative hip joint function, there was no significant difference in Harris score between the two groups of patients at 6-month follow-up（P>0.05）. CONCLUSION: Compared with manual operation of FNS, orthopedic robot assisted FNS in the treatment of femoral neck fractures can help shorten surgical time, reduce intraoperative fluoroscopy frequency, and have similar therapeutic effects on long-term hip joint function recovery.

[Adsorption Performance of Walnut Green Husk Biochar for Heavy Metals].

The biochars of WP300, WP500, and WP700 were prepared by pyrolyzing walnut green husk under 300℃, 500℃, and 700℃ with the oxygen-free condition for removing Pb2+, Cu2+, and Cd2+ in an aqueous solution. The results revealed that WP500 prepared under the medium pyrolysis temperature achieved the best adsorption performance for heavy metals, and the highest removal efficiency was reached when the solution pH was 8, in which the removal efficiency of Pb2+, Cu2+, and Cd2+ were 97.87%, 99.78%, and 71.15%, respectively. The required biochar dosage for heavy metal removal varied under different adsorption conditions. In the single-metal system, the optimal dosage for WP500 in the Pb2+, Cu2+, and Cd2+ solutions was 1.3 g·L-1, 2.1 g·L-1, and 1.9 g·L-1, respectively, whereas in the pollution metals system, the optimal biochar dosage was 5.1 g·L-1. In addition, the adsorption capacity of WP500 for the three heavy metals followed the order of Pb2+>Cu2+>Cd2+ under the single and combined-metals system, indicating that there were no synergistic or antagonistic effects among these three adsorbates. The fitting results of the adsorption isotherm model suggested that various immobilization methods existed in adsorption process between WP500 and Pb2+, Cu2+, and Cd2+. The kinetic fitting results suggested that the main reaction between WP500 and Pb2+, Cu2+, and Cd2+ was chemical adsorption. The mechanisms of WP500 for heavy metals involved pore-filling, electrostatic attraction, ion-exchange, mineral precipitation, complexation, and π-π electron donor-accepter interaction. To conclude, this study offered a new insight for the resource utilization of the waste walnut green husk.

Strain-driven Kovacs-like memory effect in glasses.

Studying complex relaxation behaviors is of critical importance for understanding the nature of glasses. Here we report a Kovacs-like memory effect in glasses, manifested by non-monotonic stress relaxation during two-step high-to-low strains stimulations. During the stress relaxation process, if the strain jumps from a higher state to a lower state, the stress does not continue to decrease, but increases first and then decreases. The memory effect becomes stronger when the atomic motions become highly collective with a large activation energy, e.g. the strain in the first stage is larger, the temperature is higher, and the stimulation is longer. The physical origin of the stress memory effect is studied based on the relaxation kinetics and the in-situ synchrotron X-ray experiments. The stress memory effect is probably a universal phenomenon in different types of glasses.

[Percutaneous pelvic fracture stabilization using CT-based 3D navigation software combined with targeting mechanical arm: a cadaver model trial].

OBJECTIVES: To investigate a new targeting mechanical arm for CT-based navigated percutaneous fixation of pelvic fractures, and to evaluate the safety and efficiency of the procedures. METHODS: Using CT-based 3D navigation software combined with targeting mechanical arm, percutaneous insertion of pelvic models (3 dry human cadaver pelvic skeletons and 5 plastic Sybone pelvic models) were performed, 8 pelvic models allowed percutaneous cannulated screw insertion of both S-I joint (2 S-I screws placement for each side, total 32 screws in this experiment) and both superior ramus (1 ramus medullary screw placement for each side, total 16 screws in this experiment). Percutaneous insertion of pelvic models (4 dry human cadaver pelvic skeletons and 4 plastic Sybone pelvic models, 1 S-I screws and 1 ramus medullary scre placement for each side, 32 screws in this experiment) were performed using fluoro-navigation system (Stryker, USA). Time necessary for every screw insertion were recorded. Accuracy of screw placement was assessed using C-arm imaging and direct eyes inspecting. The time and accuracy of the two methods were compared. RESULTS: The time required for the CT-based 3D navigation procedure (3.6 ± 1.2) min was significantly less than using the targeting mechanical arm compared to drilling freehand with navigation (9.1 ± 0.8) min (t = 2.50, P < 0.01). There was no significant difference in accuracy between the two methods. CONCLUSION: CT-based 3D navigation software combined with targeting mechanical arm should be potential to apply percutaneous sacroiliac screwing for pelvic fractures with more accurate and more reliable.

Quantifying Concentration Fluctuations in Binary Glass-Forming Systems by Small- and Wide-Angle X-ray Scattering.

Functionality of amorphous multicomponent systems largely depends upon the miscibility among components, especially in systems such as amorphous drugs and electrolytes. An in-depth understanding of mixing behaviors of various constituents is necessitated. Here, we applied the small- and wide-angle X-ray scattering (SWAXS) technique to monitor the mixing behaviors in three typical glass-forming binary systems imposed by varied heat of mixing. It is found that the Porod invariant (Q) determined at the glass transition temperature is remarkably enhanced as the concentration fluctuation becomes intensified. Meanwhile, the deviation of Q from the ideal mixing law is markedly weaken at elevated temperatures. The results unambiguously suggest that the degree of concentration fluctuations in mixing systems can be accurately quantified by the structural property, allowing the link to mixing thermodynamics.

Key Role of Lorentz Excitation in the Electromagnetic-Enhanced Hydrogen Evolution Reaction.

Alternating magnetic fields (AMFs) are recently demonstrated as a promising strategy to promote the electrochemical catalytic reactions. However, the underlying mechanisms are still an open question. In this work, we systematically investigated the influence of AMFs on the hydrogen evolution reaction (HER) by using a Fe-Co-Ni-P-B magnetic catalyst. The HER catalytic efficiency is boosted significantly by AMFs, with 27% increase in current density at 20 mT. This is attributed to the enhancement of charge-transfer efficiency by Lorentz interaction with a minor contribution from the heating effect. The high magnetic permeability and skin effect of electromagnetic eddy current for the Fe-Co-Ni-P-B electrode can magnify the Lorentz effect. These findings clarify the mechanism of AMF-enhanced HER catalytic activities and open a door for designing a high-efficiency electrocatalysis system.

Percutaneous Robot-Assisted versus Freehand S2 Iliosacral Screw Fixation in Unstable Posterior Pelvic Ring Fracture.

OBJECTIVES: To assess the efficiency, safety, and accuracy of S2 (IS) screw fixation using a robot-assisted method compared with a freehand method. METHODS: This is a retrospective clinical study. We analyzed the patients treated with S2 IS screw fixation for unstable pelvic fractures from January 2016 to January 2019 in our institution. Sixty-three patients (17 men and 46 women) aged between 21 and 55 years (with an average age of 39.22 ± 9.28) were included in this study. According to the Tile classification, there were 26 (41.3%) type B fractures and 37 (58.7%) type C fractures. All patients were divided into robot-assisted (RA) group (38 patients) or the traditional freehand (FH) group (25 patients). In RA group, the S2 IS screws were implanted with a robot-assisted technique. And S2 IS screws were implanted with a traditional freehand technique in FH group. The screw-related complications were recorded during and after the surgery. The position of all screws and fracture reduction was assessed by postoperative CT scans according to the Gras classification. The number of guide wire attempts and the radiation exposure for S2 screw implantation during operation were also recorded. Finally, the Matta standard was used to evaluate the fracture reduction of the IS joint. RESULTS: A total of 89 IS screws were implanted into S2 iliosacral joint. Fifty-four screws were placed by RA (38 patients) and 35 screws were by FH (25 patients). There was no difference between the two groups with respect to demographic data. There was no screw-related complications or revision surgery in any group. In terms of screw placement, the excellent and good rate was 100% in the RA group, better than that in the FH group where it was only 85.7% (P < 0.001). The fluoroscopy time was 8.06 ± 3.54 s in RA group, which was much less than that in the FH group (27.37 ± 8.82 s, P < 0.001). The guide wire attempts in the RA group (0.685 ± 0.820) were much less than those in the FH group (5.77 ± 3.34) (P < 0.001). Both the fluoroscopy time per screw and the number of guide wire attempts in the RA group were much less than those in the FH group (P < 0.001). The overall postoperative excellent and good rate of Matta standard in RA and FH groups were 86.8% (34/4) and 90.0% (23/25), respectively (P = 0.750), and there was no statistical difference. CONCLUSION: The robot-assisted surgery is an accurate and minimally invasive technique. S2 IS screw implantation assisted by TiRobot to treat the posterior pelvic ring fractures, have a high success rate than the freehand technique. Percutaneous RA S2 IS screw fixation for unstable posterior pelvic ring injuries is safe and clinically feasible and has great clinical application value.

Effect of Local Delivery of Vancomycin and Tobramycin on Bone Regeneration.

OBJECTIVE: A bone defect rat model was established to investigate the osteogenic effect of local delivery two antibiotics (vancomycin and tobramycin powder) on bone regeneration. METHODS: Twenty-four Sprague-Dawley (SD) male rats (6 to 8 weeks, 200 to 250 g) were used in this study. All these rats were randomly divided into four groups. Based on dose conversion between rat and human via body surface area, the rat dose of two antibiotics was 88µg/g and 176 µg/g for vancomycin and tobramycin, respectively. Con group (no antibiotic), Van group (vancomycin, 88 µg/g), Tob group (tobramycin 176 µg/g), and Van+Tob group (vancomycin 88µg/g combined with tobramycin 176 µg/g). A 5.0-mm full-thickness standardized mandibular bone defect was performed with a drill in each rat and different antibiotic powders were placed over the bone defect space, respectively. All these animals were sacrificed after 12 weeks post-operation. The mandible bones were harvested for further radiographic and histologic analysis. The bone volume/total volume (BV/TV) ratio, bone volume (BV), and bone fractional area (BFA) in the defect area via micro-computed tomography (µCT scanning) were further analyzed. Then, we performed a histological assessment via hematoxylin and eosin (H&E) and Masson's trichrome staining to analyze bone regeneration and also analyze the number of osteoblasts per filed. RESULTS: There were no postoperative deaths, signs of vancomycin-related or tobramycin-related toxicity, or signs of systemic illness in any of the four groups. All wounds healed well, and no complications or surgical site infection were observed in all rats. From the µCT scans analyses, there was less bone regeneration in the Van group than in the Con group (BV/TV: F = 64.29, R2  = 0.9602; P = 0.0052; BFA: F = 76.17, R2  = 0.9662, P = 0.0007; BV: F = 194.4, R2  = 0.9865, P = 0.0022). However, when the tobramycin and vancomycin were combined, an increase in bone defect re-ossification was found in the Van+Tob group than in the Van group (BV/TV: F = 64.29, R2  = 0.9602, P = 0.0033; BFA: F = 76.17, R2  = 0.9662, P = 0.0006; BV: F = 194.4, R2  = 0.9865, P = 0.0033). Routine H&E and Masson staining supported the finding of µCT scanning. Quantitative indices confirmed that both the bone regeneration and the number of osteoblasts per filed in the defect area was higher in the Van+Tob group than in the Van group (percentage of bone tissue: F = 145.7, R2  = 0.9562, P = 0.0008; number of osteoblasts per file; F = 67.3, R2  = 0.9098, P < 0.0001). There was no significant difference between the Con group and the Van+Tob group on the number of osteoblasts each field (F = 145.7, R2  = 0.9562, P > 0.9999). CONCLUSION: For bone defect, local application of vancomycin combined with tobramycin was recommended over vancomycin alone. This animal study presents data suggesting that the use of local delivery of vancomycin and tobramycin should be investigated further in clinical studies.

[Primary clinical application of traction reductor for lower limb fracture].

OBJECTIVE: To develop a traction reductor for the reduction of lower limb fractures during the minimally invasive surgery and explore its safety and efficacy. METHODS: From February 2007 to March 2009, closed or limited open reduction plus percutaneous plate and screw internal-fixation were conducted in 34 patients with fracture of distal femur and tibia metaphysic, among which there were 3 distal femoral fractures (2 33-B, 1 33-C), 14 proximal tibial fractures (9 41-A, 3 41-B, 2 41-C) and 17 distal tibial fractures (9 43-A, 5 43-B, 3 43-C, 2 Gustilo I a), according to the Association for Osteosynthesis-Orthopaedic Trauma Association (AO-OTA) classification. Besides, closed reduction plus interlocking intramedullary nailing on tibial shaft fracture were applied in 36 patients (7 42-A, 21 42-B, 8 42-C, 2 Gustilo I a). All the 70 patients, with an average age of 37.6 years (range: 17 to 63 years) and average time before surgery of 4.7 d (range: 0.7 to 12.0 d), underwent reduction by self-designed traction reductor for lower limb fracture in the surgery. The reduction duration and C-arm fluoroscopy time were recorded. Recovery of the force line of affected limbs after surgery was determined by whether the line from anterior superior iliac spine to the interdigit between the first and second toe-web passed the patella center. And the distance from bilateral anterior superior iliac spine to medial malleolus tip as well as the difference between lower limbs were recorded to determine the recovery of length after surgery. Meanwhile, the varus-valgus and anteroposterior angulations after reduction were measured by AP and lateral X-ray. RESULTS: The reduction duration was 12.7 min (range: 7 to 31 min); X-ray fluoroscopy time, 1.3 min (range: 0.4 to 3.0 min); length difference between both lower limbs (6.5 ± 1.1) mm; and axial alignment difference (7.0 ± 1.8) mm. The X-ray result showed that varus-valgus angle was (2.75 ± 0.16)°; and anteroposterior angulation (5.13 ± 0.51)°. CONCLUSION: The traction reductor for lower limb fracture could achieve satisfying fracture reduction in the minimally invasive surgery of distal femur, tibia metaphysic and tibial shaft fracture.

Entropic Nature of the Debye Relaxation in Glass-Forming Monoalcohols.

The dynamics and thermodynamics of the Debye and structural (α) relaxations in isomeric monoalcohols near the glass transition temperature Tg are explored using dielectric and calorimetric techniques. The α relaxation strength at Tg is found to correlate with the heat capacity increment, but no thermal signals can be detected to link to the Debye relaxation. We also observed that the activation energy of the Debye relaxation in monoalcohols is quantitatively correlated with that of the α relaxation at the kinetic Tg, sharing the dynamic behavior of the Rouse modes found in polymers. The experimental results together with the analogy to the Rouse modes in polymers suggest that the Debye process in monoalcohols is an entropic process manifested by the total dipole fluctuation of the supramolecular structures, which is triggered and driven by the α relaxation.

Guidance for the Treatment of Femoral Neck Fracture with Precise Minimally Invasive Internal Fixation Based on the Orthopaedic Surgery Robot Positioning System.

Femoral neck fractures are among the most common fractures in orthopaedics. There are many surgical methods for the treatment of femoral neck fracture. Percutaneous cannulated lag screw fixation for the treatment of femoral neck fractures is favored by orthopaedic doctors because of its characteristics of being minimally invasive, with less bleeding and firm fixation. However, traditional freehand screw placement is limited by many factors, and the screw malposition rate is very high, which directly leads to the reduction of its biomechanical stability, and even leads to the ischemic necrosis of the femoral head caused by damage to blood vessels. In addition, excessive attempts to drill holes can damage cancellous bone and affect the screw's holding force, which reduces the stability of internal fixation and increases the risk of failure. At the same time, too much radiation exposure to medical personnel and patients also causes great damage to the body. Robot-assisted orthopaedic surgery combines the mechanical "eye" (an infrared ray tracking device) and the mechanical "hand" (six degrees of freedom mechanical arm), and through the process of preoperative planning, intraoperative assistance in screw placement, and postoperative confirmation, provides a more minimally invasive and precise treatment method for this kind of surgery, and significantly reduces radiation exposure. This guide uses the TiRobot system as an example to describe the robot surgery in detail, aiming at standardizing the application of robots in orthopaedic surgery.

Guidance for Treatment of Pelvic Acetabular Injuries with Precise Minimally Invasive Internal Fixation Based on the Orthopaedic Surgery Robot Positioning System.

Pelvic acetabular fracture is a common kind of fracture, mostly caused by high energy injuries. It is associated with high mortality and disability rates. The aim of surgical treatment of pelvic acetabular fractures is to restore the symmetry and stability of the pelvic ring structure and the anatomical structure of acetabular. Open reduction internal fixation is often used for the treatment of such fractures, but open surgery is in cases of serious injury, more bleeding, and high risk of infection. With the development of minimally invasive technology and the concept of the bone channel structure, the percutaneous lag screw technique for the treatment of pelvic and acetabular fractures has been applied in clinical practice and has proven to be effective. However, the anatomical structure of the pelvis and acetabulum is complex, and there are many important nerves and vessels adjacent to it. Traditional fluoroscopy screw placement is prone to screw malposition, and even minor angle changes may lead to screw perforation and damage of nerve vessels. The problem of radiation exposure is also noteworthy. Robotic-assisted surgery can be used to carry out screw position planning through preoperative imaging, intraoperative real-time tracking, and mechanical arm assistance to ensure that the screw placement position is consistent with the planning. In this way, robotic-assisted surgery can be used to accurately insert lag screws, and can reduce surgical risk and radiation exposure. This guide uses the TiRobot system as an example to describe the application of robot surgery in detail, aiming at standardizing the application of robots in orthopaedic surgery.

Evaluation of a Bi-Planar Robot Navigation System for Insertion of Cannulated Screws in Femoral Neck Fractures.

OBJECTIVE: To evaluate the bi-planar robot navigation system for insertion of cannulated screws in femoral neck fractures. METHOD: Between January 2016 and December 2016, 60 patients with femoral neck fractures were separately treated using percutaneous cannulated screws assisted by the bi-planar robot navigation system (robot group) and conventional freehand surgery (freehand group). The fluoroscopy time, the number of drilling attempts, and the operation time were recorded during operations; the dispersion and parallelism of the cannulated screws on the posteroanterior and lateral images were measured after operations. Patients were followed up for 12-24 months and the Harris scores and the final results of the two groups were compared. RESULTS: During bi-planar robot navigation system-assisted surgery, the fluoroscopy time for acquisition of images was 2.3 seconds on average, and the time for planning screws during the operation was 2.8 min on average. The average fluoroscopy time during the placement of the guide pin was 5.7 seconds and 14.14 seconds (P = 0.00), respectively. The average time of the placement of the cannulated screws was 12.7 min and 19.4 min (P = 0.00), respectively, in the robot group and the freehand group. In the robot group, only one guide pin was replaced during the operation, and the average number of adjustments for each guide pin was 2.39 in the freehand group. The screw parallelism and dispersion measured by postoperative imaging in the robot group were significantly superior to those in the freehand group. From postoperative CT it was evident that there were 5 cases of screws exiting the posterior cortex in both groups. During the follow-up phase, 1 case of femoral head necrosis and 5 cases of femoral neck shortening of more than 10 mm occurred in the robotic navigation group; 3 cases of femoral head necrosis, 1 case of fracture nonunion, and 2 cases of shortening of more than 10 mm occurred in the freehand group. At 18 months after surgery, the average Harris scores of the patients were 85.20 and 83.45, respectively, with no significant difference. CONCLUSION: Using bi-planar robot navigation system-assisted placement of femoral neck cannulated screws can significantly reduce the time of intraoperative fluoroscopy, drilling attempts, and operation time. The placed screws are superior to the screws placed freehand in relation to parallelism and dispersion. However, it is still necessary for surgeons to have a good reduction of the femoral neck fracture before surgery and to be proficient in the operation of the robot navigation system. In summary, the bi-planar robot navigation system is an effective assistant instrument for surgery.