Transfer film effects induced by 3D-printed polyether-ether-ketone with excellent tribological properties for joint prosthesis

Based on the building principle of additive manufacturing,printing orientation mainly determines the tribological properties of joint prostheses.In this study,we created a polyether-ether-ketone(PEEK)joint prosthesis using fused filament fabrication and investigated the effects of printing orientation on its tribological properties using a pin-on-plate tribometer in 25% newborn calf serum.An ultrahigh molecular weight polyethylene transfer film is formed on the surface of PEEK due to the mechanical capture of wear debris by the 3D-printed groove morphology,which is significantly impacted by the printing orientation of PEEK.When the printing orientation was parallel to the sliding direction of friction,the number and size of the transfer film increased due to higher steady stress.This transfer film protected the matrix and reduced the friction coefficient and wear rate of friction pairs by 39.13%and 74.33%,respectively.Furthermore,our findings provide a novel perspective regarding the role of printing orientation in designing knee prostheses,facilitating its practical applications.

Diagnostic value of serum Interleukin-6 combined with synovial IL-6 and C-reactive protein for prosthesis joint infection in patients after joint arthroplasty

Objective:To explore the diagnostic value of serum Interleukin-6(IL-6)combined with synovial IL-6 and C-reactive protein for prosthesis joint infection(PJI)in patients after joint arthroplasty.Methods:A total of 253 patients undergoing revision surgery after the first total hip and total knee arthroplasty in the Second Affiliated Hospital of Hainan Medical College from January 2018 to April 2020 were recruited as the study object.The patients were divided into the PJI group(n=85)and non-PJI group(n=168)according to whether there was PJI,and the baseline characteristics and the laboratory indexe were collected and compared between the two groups.the factors associated with PJI in patients after joint arthroplasty were analyzed by multivariate logistic regression model.And the diagnostic value of each marker for PJI in patients after joint arthroplasty was evaluated by Receiver Operating Characteristic(ROC)curve.Results:The incidence of PJI in this study was 33.6%.Compared with the non-PJI group,the patients in the PJI group had more diabetes mellitus and shorter prosthesis duration(P<0.05).The levels of serum C-reactive protein(CRP),serum interleukin-6(IL-6),synovial IL-6,synovial CRP,synovial leukocyte,synovial neutrophil and ESR in the PJI group were higher than those in non-PJI group,and the level of synovial lymphocyte was lower,with statistically significant differences(P<0.05).Multivariate logistic regression analysis showed that diabetes mellitus(OR=1.706,95%CI:1.02~2.376,P=0.037),prosthesis duration(OR=0.781,95%CI:0.690~0.884,P<0.001),serum IL-6(OR=1.008,95%CI:1.004~1.012,P=0.046),synovial IL-6(OR=1.004,95%CI:1.002~1.006,P=0.011)and synovial CRP(OR=1.481,95%CI:1.010~2.170,P=0.044)were independently related to PJI in patients after joint arthroplasty.ROC curve analysis showed that the area under ROC curve(AUC)of serum IL-6 combined with synovial IL-6 and CRP for diagnose PJI in patients after joint arthroplasty was significantly greater than each marker(0.941 vs 0.760,Z=6.333,P<0.001;0.941 vs 0.743,Z=7.189,P<0.001;0.941 vs 0.785,Z=4.999,P=0.006).Conclusion:Serum IL-6,synovial IL-6 and CRP were independently related to PJI in patients after joint arthroplasty.They all had some diagnostic value,and serum IL-6 combined with synovial IL-6 and CRP had higher capability to diagnose PJI in patients after joint arthroplasty than each marker alone.

Can periprosthetic hip joint infections be successfully managed by debridement and prosthesis retention?

To evaluate the current literature about how successfully periprosthetic hip joint infections can be managed by debridement and prosthesis retention.A literature search was performed through Pub Med until September 2013.Search terms were"DAIR(debridement,antibiotics,irrigation,and retention)"alone and in combination with"hip"as well as"hip infection+prosthesis retention".A total of 11 studies reporting on 292 cases could be identified.Five different treatment modalities have been described with varying success rates(debridement-21%infection eradication rate;debridement+lavage-75%infection eradication rate;debridement,lavage,with change of modular prosthesis components-70.4%infection eradication rate;debridement,lavage,change of modular prosthesis components+vacuum-assisted closure-92.8%infection eradication rate;acetabular cup removal+spacer head onto retained stem-89.6%infection eradication rate).With regard to the postoperative antibiotic therapy,no general consensus could be drawn from the available data.Debridement,antibiotic therapy,irrigation,and prosthesis retention is an acceptable solution in the management of early and acute hematogenous periprosthetic hip joint infections.The current literature does not allow for generalization of conclusions with regard to thebest treatment modality.A large,multi-center study is required for identification of the optimal treatment of these infections.

Knowledge and attitudes of orthopedic surgeons regarding prosthesis joint infection

BACKGROUND Periprosthetic joint infection(PJI)is a critical complication after joint arthroplasty and is accompanied by increasing rates of morbidity and mortality.Several studies have aimed at preventing PJI.AIM To research the knowledge level and attitudes of orthopedic surgeons,who play a key role in both preventing and managing PJI.METHODS We conducted a web-based survey to evaluate orthopedic surgeons'knowledge level and attitudes regarding PJI.The Likert scale survey utilized consisted of 30 questions which were prepared based on the"Proceedings of the International Consensus on Periprosthetic Joint Infection".RESULTS A total of 264 surgeons participated in the survey.Their average age was 44.8,and 173 participants(65.5%)had more than 10 years of experience.No statistically significant relationship was found between the PJI knowledge of the surgeons and their years of experience.However,participants who worked in training and research hospitals demonstrated higher levels of knowledge than the ones in the state hospitals.It was also noticed that surgeons'knowledge concerning the duration of antibiotic therapy and urinary infections was not consistent with their attitudes.CONCLUSION Even though orthopedic surgeons have adequate knowledge about preventing and managing PJI,their attitudes might contradict their knowledge.Future studies are required to examine the causes and solutions of the contradictions between orthopedic surgeons'knowledge and attitudes.

RANK-ligand and osteoprotegerin as biomarkers in the differentiation between periprosthetic joint infection and aseptic prosthesis loosening

AIM To assess serum levels of RANK-ligand(RANKL) and osteoprotegerin(OPG) as biomarkers for periprosthetic joint infection(PJI) and compare their accuracy with standard tests.METHODS One hundred and twenty patients presenting with a painful total knee or hip arthroplasty with indication for surgical revision were included in this prospective clinical trial. Based on standard diagnostics(joint aspirate, microbiological, and histological samples) and Musculoskeletal Infection Society consensus classification,patients were categorized into PJI, aseptic loosening,and control groups. Implant loosening was assessed radiographically and intraoperatively. Preoperative serum samples were collected and analyzed for RANKL, OPG, calcium, phosphate, alkaline phosphatase(AP), and the bone-specific subform of AP(b AP). Statistical analysis was carried out, testing for significant differences between the three groups and between stable and loose implants. RESULTS All three groups were identical in regards to age, gender, and joint distribution. No statistically significant differences in the serum concentration of RANKL(P = 0.16) and OPG(P = 0.45) were found between aseptic loosening and PJI, with a trend towards lower RANKL concentrations and higher OPG concentrations in the PJI group. The RANKL/OPG ratio was significant for the comparison between PJI and non-PJI(P = 0.005). A ratio > 60 ruled out PJI in all cases(specificity: 100%, 95%CI: 89, 11% to 100.0%) but only 30% of non-PJI patients crossed this threshold. The positive predictive value remained poor at any cut-off. In the differentiation between stable and loose implants, none of the parameters measured(calcium, phosphate, AP, and b AP) showed a significant difference, and only AP and b AP measurements showed a tendency towards higher values in the loosened group(with P = 0.09 for AP and P = 0.19 for b AP). CONCLUSION Lower RANKL and higher OPG concentrations could be detected in PJI, without statistical significance.

Topology Optimization and Fatigue Analysis of Temporomandibular Joint Prosthesis

Treatment of bone tumors in the mandible often involves extensive excavation of affected bone, followed by mandibular reconstruction. Prosthetic implants may be needed to restore jaw functionality. The challenges of making prosthetic bone implants include stress shielding and extending the mechanical life of the implant. We have developed a design algorithm to improve the efficiency of prosthesis design. A finite element model of the patient case is constructed from a computer tomography scan, and the computer implements topology optimization techniques to design the prosthesis with limited stress shielding affected by highly biomechanical compatibility. Topology optimization facilitates the design of low weight structures by automatically introducing holes into the structure. This is governed by engineering predetermined constraints to meet certain job specifications. Such a design will be tested for fatigue life before it is ready to be manufactured and used. Topology optimization can be performed as a design process to achieve a final design that takes stress shielding into consideration. The problem of stress shielding is solved by matching the stiffness of the orthopedic implant to the original bone that is being replaced. The material we used was titanium alloy (Ti-6Al-7Nb). Volume fraction of the orthodox implant was used (0.2872 for the studied case) as volume constraints. Compliance of the bulk bone was set as a further constraint to match the stiffness of the bone with the designed structure. Our results show a good life expectancy for the designed parts, with 12% higher life expectancy for stress-based topology optimization than for compliance-based topology optimization.

Preparation for femur prosthesis of ceramic-metal combination artificial hip joint

Al 2O 3 material was synthesized by using high purity alumina micro powder and Mg Zr Y composite additives at temperature of 1 600 ℃, which had good mechanics property of 416 MPa bending strength and 5.46 MPa·m 1/2 fracture toughness. Femur head prosthesis of hip joint was prepared by using this material; Ti alloy femur handle was sprayed bioactive hydroxyapatite (HA) by plasma on surface, which improves the chemistry stability and biocompatibility of Ti alloy; ceramic metal combination artificial hip joint femur prosthesis was made by combining Al 2O 3 femur head with Ti alloy femur handle, so the manufacturing process is improved and the property and application flexibility are advanced.

Subsequent total joint arthroplasty: Are we learning from the first stage?

BACKGROUND With the increasing incidence of total joint arthroplasty(TJA),there is a desire to reduce peri-operative complications and resource utilization.As degenerative conditions progress in multiple joints,many patients undergo multiple proce-dures.AIM To determine if both physicians and patients learn from the patient’s initial arth-roplasty,resulting in improved outcomes following the second procedure.METHODS The institutional database was retrospectively queried for primary total hip arth-roplasty(THA)and total knee arthroplasty(TKA).Patients with only unilateral THA or TKA,and patients undergoing same-day bilateral TJA,were excluded.Patient demographics,comorbidities,and implant sizes were collected at the time of each procedure and patients were stratified by first vs second surgery.Outcome metrics evaluated included operative time,length of stay(LOS),disposition,90-d readmissions and emergency department(ED)visits.RESULTS A total of 642 patients,including 364 undergoing staged bilateral TKA and 278 undergoing bilateral THA,were analyzed.There was no significant difference in demographics or comorbidities between the first and second procedure,which were separated by a mean of 285 d.For THA and TKA,LOS was significantly less for the second surgery,with 66%of patients having a shorter hospitalization(P<0.001).THA patients had significantly decreased operative time only when the same sized implant was utilized(P=0.025).The vast majority(93.3%)of patients were discharged to the same type of location following their second surgery.However,when a change in disposition was present from the first surgery,patients were significantly more likely to be discharged to home after the second procedure(P=0.033).There was no difference between procedures for post-operative readmissions(P=0.438)or ED visits(P=0.915).CONCLUSION After gaining valuable experience recovering from the initial surgery,a patient’s perioperative outcomes are improved for their second TJA.This may be the result of increased confidence and decreased anxiety,and it supports the theory that enhanced patient education pre-operatively may improve outcomes.For the surgical team,the second procedure of a staged THA is more efficient,although this finding did not hold for TKA.

Investigation into the analysis method for assessing contact stress in joint prosthesis

Contact stress is the important cause of wear and failure of knee joint prostheses implanted in the human body during movement.The calculation of contact stress on joint prostheses is often inaccurate due to the deviation of joint position during activity.This paper proposes a correction method for contact stress based on finite element results.Firstly,the contact stress and contact radius between femoral and tibial prostheses of knee joint were calculated and analyzed by Hertz contact theory.Then,individualized finite element models based on the individualized geometry of the joint prosthesis and individualized loading were constructed,and the finite element contact stress was analyzed.The finite element results were calibrated utilizing the Hertz contact theory.Additionally,this study investigated the impact of three gait patterns(normal gait,medial thrust gait,and bouncing gait)on the contact stress experienced by the tibial insert.The research methods and results can provide ideas for theoretical analysis and finite element simulation of prosthetic joint contact,as well as offer theoretical support and analysis methods for evaluating the lifespan of prosthetic joints.

A photogrammetric approach for quantifying the evolution of rock joint void geometry under varying contact states

Accurate measurement of the evolution of rock joint void geometry is essential for comprehending the distribution characteristics of asperities responsible for shear and seepage behaviors.However,existing techniques often require specialized equipment and skilled operators,posing practical challenges.In this study,a cost-effective photogrammetric approach is proposed.Particularly,local coordinate systems are established to facilitate the alignment and precise quantification of the relative position between two halves of a rock joint.Push/pull tests are conducted on rock joints with varying roughness levels to induce different contact states.A high-precision laser scanner serves as a benchmark for evaluating the photogrammetry method.Despite certain deviations exist,the measured evolution of void geometry is generally consistent with the qualitative findings of previous studies.The photogrammetric measurements yield comparable accuracy to laser scanning,with maximum errors of 13.2%for aperture and 14.4%for void volume.Most joint matching coefficient(JMC)measurement errors are below 20%.Larger measurement errors occur primarily in highly mismatched rock joints with JMC values below 0.2,but even in cases where measurement errors exceed 80%,the maximum JMC error is only 0.0434.Thus,the proposed photogrammetric approach holds promise for widespread application in void geometry measurements in rock joints.

Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite

The damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host rock.The latter is commonly known as off-fault damage and has been much less investigated than the surface damage.The main contribution of this study is to compare the results of direct shear tests conducted on saw-cut planar joints and tension-induced rough granite joints under normal stresses ranging from 1 MPa to 50 MPa.The shear-induced off-fault damages are quantified and compared with the optical microscope observation.Our results clearly show that the planar joints slip stably under all the normal stresses except under 50 MPa,where some local fractures and regular stick-slip occur towards the end of the test.Both post-peak stress drop and stick-slip occur for all the rough joints.The residual shear strength envelopes for the rough joints and the peak shear strength envelope for the planar joints almost overlap.The root mean square(RMS)of asperity height for the rough joints decreases while it increases for the planar joint after shear,and a larger normal stress usually leads to a more significant decrease or increase in RMS.Besides,the extent of off-fault damage(or damage zone)increases with normal stress for both planar and rough joints,and it is restricted to a very thin layer with limited micro-cracks beneath the planar joint surface.In comparison,the thickness of the damage zone for the rough joints is about an order of magnitude larger than that of the planar joints,and the coalesced micro-cracks are generally inclined to the shear direction with acute angles.The findings obtained in this study contribute to a better understanding on the frictional behavior and damage characteristics of rock joints or fractures with different roughness.

Three‑dimensional numerical simulation of dynamic strength and failure mode of a rock mass with cross joints

To study the dynamic mechanical properties and failure characteristics of intersecting jointed rock masses with different joint distributions under confining pressure,considering the cross angleαand joint persistence ratioη,a numerical model of the biaxial Hopkinson bar test system was established using the finite element method–discrete-element model coupling method.The validity of the model was verified by comparing and analyzing it in conjunction with laboratory test results.Dynamics-static combined impact tests were conducted on specimens under various conditions to investigate the strength characteristics and patterns of crack initiation and expansion.The study revealed the predominant factors influencing intersecting joints with different angles and penetrations under impact loading.The results show that the peak stress of the specimens decreases first and then increases with the increase of the cross angle.Whenα<60°,regardless of the value ofη,the dynamic stress of the specimens is controlled by the main joint.Whenα≥60°,the peak stress borne by the specimens decreases with increasingη.Whenα<60°,the initiation and propagation of cracks in the cross-jointed specimens are mainly controlled by the main joint,and the final failure surface of the specimens is composed of the main joint and wing cracks.Whenα≥60°orη≥0.67,the secondary joint guides the expansion of the wing cracks,and multiple failure surfaces composed of main and secondary joints,wing cracks,and co-planar cracks are formed.Increasing lateral confinement significantly increases the dynamic peak stress able to be borne by the specimens.Under triaxial conditions,the degree of failure of the intersecting jointed specimens is much lower than that under uniaxial and biaxial conditions.

RB-DEM Modeling and Simulation of Non-Persisting Rough Open Joints Based on the IFS-Enhanced Method

When the geological environment of rock masses is disturbed,numerous non-persisting open joints can appear within it.It is crucial to investigate the effect of open joints on the mechanical properties of rock mass.However,it has been challenging to generate realistic open joints in traditional experimental tests and numerical simulations.This paper presents a novel solution to solve the problem.By utilizing the stochastic distribution of joints and an enhanced-fractal interpolation system(IFS)method,rough curves with any orientation can be generated.The Douglas-Peucker algorithm is then applied to simplify these curves by removing unnecessary points while preserving their fundamental shape.Subsequently,open joints are created by connecting points that move to both sides of rough curves based on the aperture distribution.Mesh modeling is performed to construct the final mesh model.Finally,the RB-DEM method is applied to transform the mesh model into a discrete element model containing geometric information about these open joints.Furthermore,this study explores the impacts of rough open joint orientation,aperture,and number on rock fracture mechanics.This method provides a realistic and effective approach for modeling and simulating these non-persisting open joints.

On the calibration of a shear stress criterion for rock joints to represent the full stress-strain profile

Conventional numerical solutions developed to describe the geomechanical behavior of rock interfaces subjected to differential load emphasize peak and residual shear strengths.The detailed analysis of preand post-peak shear stress-displacement behavior is central to various time-dependent and dynamic rock mechanic problems such as rockbursts and structural instabilities in highly stressed conditions.The complete stress-displacement surface(CSDS)model was developed to describe analytically the pre-and post-peak behavior of rock interfaces under differential loads.Original formulations of the CSDS model required extensive curve-fitting iterations which limited its practical applicability and transparent integration into engineering tools.The present work proposes modifications to the CSDS model aimed at developing a comprehensive and modern calibration protocol to describe the complete shear stressdisplacement behavior of rock interfaces under differential loads.The proposed update to the CSDS model incorporates the concept of mobilized shear strength to enhance the post-peak formulations.Barton’s concepts of joint roughness coefficient(JRC)and joint compressive strength(JCS)are incorporated to facilitate empirical estimations for peak shear stress and normal closure relations.Triaxial/uniaxial compression test and direct shear test results are used to validate the updated model and exemplify the proposed calibration method.The results illustrate that the revised model successfully predicts the post-peak and complete axial stressestrain and shear stressedisplacement curves for rock joints.

Indication and surgical approach for reconstruction with endoprosthesis in bone-associated soft tissue sarcomas:Appropriate case management is vital

It is important for surgeons performing sarcoma surgery to know that bone resection and tumor prosthesis applications in soft tissue sarcomas(STS)have unique features in terms of indication,surgical approach and follow-up,in terms of the management of these cases.Some STS are associated with bone and major neurovascular structures.Bone-associated STS are generally relatively large and relatively deep-seated.Additionally,the tendency for metastasis is high.In some cases,the decision about which structures to resect is difficult.These cases are often accompanied by poor oncological and surgical outcomes.Management of cases should be done by a multidisciplinary team in advanced centers specialized in this field.The surgical team must have sufficient knowledge and experience in the field of limb-sparing surgery.Preoperative evaluation and especially good planning of bone and soft tissue reconstruction are vital.

Analysis of The Value of Multi-Slice Spiral CT and Magnetic Resonance Imaging in The Diagnosis of Carpal Joint Injury

Objective:To analyze the value of multi-slice spiral computed tomography(CT)and magnetic resonance imaging(MRI)in the diagnosis of carpal joint injury.Methods:A total of 130 patients with suspected wrist injuries admitted to the Department of Orthopedics of our hospital from January 2023 to January 2024 were selected and randomly divided into a single group(n=65)and a joint group(n=65).The single group was diagnosed using multi-slice spiral CT,and the joint group was diagnosed using multi-slice spiral CT and magnetic resonance imaging,with pathological diagnosis as the gold standard.The diagnostic results of both groups were compared to the gold standard,and the diagnostic energy efficiency of both groups was compared.Results:The diagnostic results of the single group compared with the gold standard were significant(P<0.05).The diagnostic results of the joint group compared with the gold standard were not significant(P>0.05).The sensitivity and accuracy of diagnosis in the joint group were significantly higher than that in the single group(P<0.05).The specificity of diagnosis in the joint group was higher as compared to that in the single group(P>0.05).Conclusion:The combination of multi-slice spiral CT and MRI was highly accurate in diagnosing wrist injuries,and the misdiagnosis rate and leakage rate were relatively low.Hence,this diagnostic program is recommended to be popularized.

Blood metal concentrations and cardiac structure and function in total joint arthroplasty patients

BACKGROUND There is concern regarding potential long-term cardiotoxicity with systemic distribution of metals in total joint arthroplasty(TJA)patients.AIM To determine the association of commonly used implant metals with echocardiographic measures in TJA patients.METHODS The study comprised 110 TJA patients who had a recent history of high chromium,cobalt or titanium concentrations.Patients underwent two-dimensional,three-dimensional,Doppler and speckle-strain transthoracic echocardiography and a blood draw to measure metal concentrations.Age and sex-adjusted linear and logistic regression models were used to examine the association of metal concentrations(exposure)with echocardiographic measures(outcome).RESULTS Higher cobalt concentrations were associated with increased left ventricular end-diastolic volume(estimate 5.09;95%CI:0.02-10.17)as well as left atrial and right ventricular dilation,particularly in men but no changes in cardiac function.Higher titanium concentrations were associated with a reduction in left ventricle global longitudinal strain(estimate 0.38;95%CI:0.70 to 0.06)and cardiac index(estimate 0.08;95%CI,-0.15 to-0.01).CONCLUSION Elevated cobalt and titanium concentrations may be associated with structural and functional cardiac changes in some patients.Longitudinal studies are warranted to better understand the systemic effects of metals in TJA patients.

Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions

To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)conditions.We analyzed the evolution of shear stress,normal stress,stress path,dilatancy characteristics,and friction coefficient and revealed the failure mechanisms of en-echelon joints at different angles.The results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle,with the shear strength at a positive angle exceeding that at a negative angle during shear cycles.As the number of cycles increases,the shear strength decreases rapidly,and the difference between the varying angles gradually decreases.Dilation occurs in the early shear cycles(1 and 2),while contraction is the main feature in later cycles(310).The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear cycles.The joint angle determines the asperities on the rupture surfaces and the block size,and thus determines the subsequent shear failure mode(block crushing and asperity degradation).At positive angles,block size is more greater and asperities on the rupture surface are smaller than at nonpositive angles.Therefore,the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles.

Analysis of the joint detection capability of the SMILE satellite and EISCAT-3D radar

The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)satellite is a small magnetosphere–ionosphere link explorer developed cooperatively between China and Europe.It pioneers the use of X-ray imaging technology to perform large-scale imaging of the Earth’s magnetosheath and polar cusp regions.It uses a high-precision ultraviolet imager to image the overall configuration of the aurora and monitor changes in the source of solar wind in real time,using in situ detection instruments to improve human understanding of the relationship between solar activity and changes in the Earth’s magnetic field.The SMILE satellite is scheduled to launch in 2025.The European Incoherent Scatter Sciences Association(EISCAT)-3D radar is a new generation of European incoherent scatter radar constructed by EISCAT and is the most advanced ground-based ionospheric experimental device in the high-latitude polar region.It has multibeam and multidirectional quasi-real-time three-dimensional(3D)imaging capabilities,continuous monitoring and operation capabilities,and multiple-baseline interferometry capabilities.Joint detection by the SMILE satellite and the EISCAT-3D radar is of great significance for revealing the coupling process of the solar wind–magnetosphere–ionosphere.Therefore,we performed an analysis of the joint detection capability of the SMILE satellite and EISCAT-3D,analyzed the period during which the two can perform joint detection,and defined the key scientific problems that can be solved by joint detection.In addition,we developed Web-based software to search for and visualize the joint detection period of the SMILE satellite and EISCAT-3D radar,which lays the foundation for subsequent joint detection experiments and scientific research.

Effect of Wearing a Maxillofacial Prosthesis on Masticatory Rhythm Improvement in Mandibulectomy Patients

Background: Recording jaw movement rhythms in patients with jaw defects is challenging using conventional tracking devices. However, masticatory rhythm is crucial for masticatory performance and nutritional intake. This study aimed to explore the impact of using a maxillofacial prosthesis to restore masticatory rhythm in mandibulectomy patients with a novel wearable device. Methods: Twelve patients who underwent mandibulectomy and were rehabilitated with maxillofacial prosthesis were recruited. Chewing rate, cycle durations, coefficient of variation of cycle durations (CV), changing times of skin morphology on the back of the ear pinna area (SM), and masticatory performance were measured during gum chewing without and with a denture using a wearable jaw movement rhythm tracking device. A paired t-test and the Pearson correlation coefficient were used for statistical analysis. Results: The chewing rate increased by 8.6 cycles/min with dentures (P P = 0.01). The CV and SM decreased with dentures (P = 0.004 and P = 0.01, respectively). Significant correlations were found between the CV and SM without dentures (P = 0.004). Conclusion: 1. Wearing maxillofacial prostheses can improve masticatory rhythm in patients who undergo mandibulectomy with Eichner B2 occlusal supports. 2. The wearable device is available for measuring masticatory rhythm in patients with jaw defects in clinics. 3. Changing times of the skin morphology on the back of the ear pinna indicate jaw movement stability through a simpler process than the coefficient of variation of cycle durations.