Prosthesis loosening is the leading cause of postoperative revision in unicompartmental knee arthroplasty (UKA). The deviation of medial and lateral translational installation of the prosthesis during surgery is a common clinical phenomenon and an important factor in increasing the risk of prosthesis loosening. This study established a UKA finite element model and a bone-prosthesis fixation interface micromotion prediction model. The predicted medial contact force and joint motion of the knee joint from a patient-specific lower extremity musculoskeletal multibody dynamics model of UKA were used as boundary conditions. The effects of 9 femoral component medial and lateral translational installation deviations on the Von Mises stress of the proximal tibia, the contact stress, and the micro-motion of the bone prosthesis fixation interface were quantitatively studied. It was found that compared with the neutral position (a/A of 0.492), the lateral translational deviation of the femoral component significantly increased the tibial Von Mises stress and the bone-prosthesis fixation interface contact stress. The maximum Von Mises stress and the maximum contact stress of the fixation interface increased by 14.08% and 143.15%, respectively, when a/A was 0.361. The medial translational deviation of the femoral component significantly increased the bone-prosthesis fixation interface micro-motion. The maximum value of micromotion under the conditions of femoral neutral and medial translation deviation was in the range of 20-50 μm, which is suitable for osseointegration. Therefore, based on considerations such as the micromotion range suitable for osseointegration reported in the literature, the risk of reducing prosthesis loosening, and factors that may induce pain, it is recommended that clinicians control the mounting position of the femoral component during surgery within the safe range of 0-4 mm medial translation deviation.
Humans ; Arthroplasty, Replacement, Knee/methods* ; Finite Element Analysis ; Biomechanical Phenomena ; Knee Prosthesis ; Tibia/surgery* ; Femur/surgery* ; Stress, Mechanical ; Prosthesis Failure ; Knee Joint/surgery* ; Prosthesis Design

The evaluation of blood compatibility of biomaterials is crucial for ensuring the clinical safety of implantable medical devices. To address the limitations of traditional testing methods in real-time monitoring and electrical property analysis, this study developed a portable electrical impedance tomography (EIT) system. The system uses a 16-electrode design, operates within a frequency range of 1 to 500 kHz, achieves a signal to noise ratio (SNR) of 69.54 dB at 50 kHz, and has a data collection speed of 20 frames per second. Experimental results show that the EIT system developed in this study is highly consistent with a microplate reader ( R ²=0.97) in detecting the hemolytic behavior of industrial-grade titanium (TA3) and titanium alloy-titanium 6 aluminum 4 vanadium (TC4) in anticoagulated bovine blood. Additionally, with the support of a multimodal image fusion Gauss-Newton one-step iterative algorithm, the system can accurately locate and monitor in real-time the dynamic changes in blood permeation and coagulation caused by TC4 in vivo. In conclusion, the EIT system developed in this study provides a new and effective method for evaluating the blood compatibility of biomaterials.
Electric Impedance ; Animals ; Tomography/instrumentation* ; Biocompatible Materials ; Materials Testing/instrumentation* ; Cattle ; Titanium ; Alloys ; Prostheses and Implants

Tesla blood pumps demonstrate a reduced propensity for hemolysis and thrombosis compared with vane blood pumps. Considering the restricted driving force within the secondary flow channel of vane blood pumps, along with the low hydraulic efficiency of conventional Tesla blood pumps and their internal flow characteristics that significantly contribute to hemolysis and thrombosis, this study introduces a set of vanes atop the rotor of the Tesla blood pump. This forms a dual-fluid domain rotor, and an axial dual-outlet volute shell structure is adopted to realize the separation of the fluid domains. Through numerical simulations of the new structure, a comparative analysis was conducted in this study on the internal flow characteristics of double-outlet and single-outlet volute shells, and symmetric and asymmetric cross-sections of the same rotor. The results indicate that the flow field distribution is more uniform under the double-outlet volute shell structure, and overall energy dissipation is decreased. After implementing the double-outlet design, in the asymmetric cross-section, compared with the symmetric cross-section, the fluid velocity gradient and turbulent kinetic energy at the tongue of the septum are reduced, and the fluid velocity gradient at the convergence of the diffuser tube outlets are also decreased. The maximum scalar stress is lower, and the decline in head and efficiency is mitigated. Moreover, compared with the single-outlet volute shell, the hemolysis index in the asymmetric cross-section is reduced. In summary, this paper proposes a novel dual-outlet centrifugal disk blood pumps, which can provide a reference for the structural design and performance optimization of magnetically levitated centrifugal blood pumps.
Heart-Assist Devices ; Humans ; Equipment Design ; Hemolysis ; Computer Simulation

This review article summarizes the current modification methods employed to enhance the osseointegration properties of polyetheretherketone (PEEK), a novel biomaterial. Our analysis highlights that strategies such as surface treatment, surface modification, and the incorporation of bioactive composites can markedly improve the bioactivity of PEEK surfaces, thus facilitating their effective integration with bone tissue. However, to ensure widespread application of PEEK in the medical field, particularly in oral implantology, additional experiments and long-term clinical evaluations are required. Looking ahead, future research should concentrate on developing innovative modification techniques and assessment methodologies to further optimize the performance of PEEK implant materials. The ultimate goal is to provide the clinical setting with even more reliable solutions.
Benzophenones ; Ketones/chemistry* ; Polyethylene Glycols/chemistry* ; Osseointegration ; Humans ; Polymers ; Biocompatible Materials/chemistry* ; Surface Properties ; Prostheses and Implants ; Dental Implants

Although metal blocks have been widely used for reconstructing uncontained tibial bone defects, the influence of their elastic modulus on the stability of tibial prosthesis fixation remains unclear. Based on this, a finite element model incorporating constrained condylar knee (CCK) prosthesis, tibia, and metal block was established. Considering the influence of the post-restraint structure of the prosthesis, the effects of variations in the elastic modulus of the block on the von Mises stress distribution in the tibia and the block, as well as on the micromotion at the bone-prosthesis fixation interface, were investigated. Results demonstrated that collision between the insert post and femoral prosthesis during tibial internal rotation increased tibial von Mises stress, significantly influencing the prediction of block elastic modulus variation. A decrease in the elastic modulus of the metal block resulted in increased von Mises stress in the proximal tibia, significantly reduced von Mises stress in the distal tibia, decreased von Mises stress of the block, and increased micromotion at the bone-prosthesis fixation interface. When the elastic modulus of the metal block fell below that of bone cement, inadequate block support substantially increased the risk of stress shielding in the distal tibia and fixation interface loosening. Therefore, this study recommends that biomechanical investigations of CCK prostheses must consider the post-constraint effect, and the elastic modulus of metal blocks for bone reconstruction should not be lower than 3 600 MPa.
Knee Prosthesis ; Humans ; Finite Element Analysis ; Tibia/surgery* ; Elastic Modulus ; Arthroplasty, Replacement, Knee/methods* ; Stress, Mechanical ; Metals ; Prosthesis Design ; Knee Joint/surgery* ; Biomechanical Phenomena

Stent migration is one of the common complications following transcatheter valve implantation. This study aims to design a "drum-shaped" balloon-expandable aortic valve stent to address this issue and conduct a mechanical analysis. The implantation process of the stent was evaluated using a method that combines numerical simulation and in vitro experiments. Furthermore, the fatigue process of the stent under pulsatile cyclic loading was simulated, and its fatigue performance was assessed using a Goodman diagram. The process of the stent migrating toward the left ventricular side was simulated, and the force-displacement curve of the stent was extracted to evaluate its anti- migration performance. The results showed that all five stent models could be crimped into a 14F sheath and enabled uniform expansion of the native valve leaflets. The stress in each stent was below the ultimate stress, so no fatigue fracture occurred. As the cell height ratio decreased, the contact area fraction between the stent and the aortic root gradually decreased. However, the mean contact force and the maximum anti-migration force first decreased and then increased. Specifically, model S5 had the smallest contact area fraction but the largest mean contact force and maximum anti-migration force, reaching approximately 0.16 MPa and 10.73 N, respectively. The designed stent achieves a "drum-shaped" change after expansion and has good anti-migration performance.
Stents ; Prosthesis Design ; Heart Valve Prosthesis ; Humans ; Aortic Valve/surgery* ; Stress, Mechanical ; Transcatheter Aortic Valve Replacement/instrumentation*

Due to their good properties of elastic modulus, degradability and ability to promote bone repair, magnesium alloys have become a research hotspot in research of orthopedic implants. Nevertheless, most of the biomedical magnesium alloys currently available fail to meet the requirements in orthopedics because of their rapid degradation after implantation. Rare earth-magnesium alloys possess excellent corrosion resistance and are expected to become important materials as clinical orthopedic implants. This review summarizes the recent progress in studies of the physiological functions of rare earth elements, the effects of supplementation of rare earth elements on biomechanical properties and the in vitro and in vivo biocompatibility of magnesium alloys, and their contribution to tendon-bone healing, addressing also the current clinical orthopedic applications of different rare earth-magnesium alloys, challenges, and future strategies for improving these alloys.
Alloys/chemistry* ; Magnesium/chemistry* ; Metals, Rare Earth/chemistry* ; Humans ; Biocompatible Materials ; Prostheses and Implants

A 91-year-old male patient was admitted with a history of mitral valve prolapse diagnosed by physical examination ten years prior and recent onset of exertional chest discomfort persisting for over one month. Transthoracic echocardiography showed that the anterior leaflet of mitral valve was thickened and prolapsed with severe regurgitation, and transesophageal echocardiography further confirmed that the anterior and posterior leaflets of mitral valve were prolapsed with massive regurgitation (A1, A2, A3, P1 and P2 were all prolapsed). Thus, the diagnosis of Barlow syndrome was considered. Transcatheter edge-to-edge mitral repair was performed with two MitraClip^TM G4 XTWs. After a 10 months follow-up, the patient's cardiac function was significantly improved, and the degree of mitral regurgitation was mild.
Humans ; Male ; Aged, 80 and over ; Mitral Valve Insufficiency/surgery* ; Mitral Valve Prolapse/diagnostic imaging* ; Cardiac Catheterization/methods* ; Mitral Valve/surgery* ; Heart Valve Prosthesis Implantation/methods*

Transcatheter aortic valve replacement (TAVR) has emerged as the standard treatment for severe aortic stenosis, demonstrating comparable efficacy to traditional surgery in low and intermediate-risk patients. However, the bioprosthetic valves utilized in TAVR have a limited lifespan, and bioprosthetic valve failure, including calcification, rupture or infection may develop, leading to poor clinical outcomes. Elevated blood pressure has been identified as a key factor in aortic valve calcification, and its role in bioprosthetic valve failure is gaining increasing attention. Hypertension may accelerate the calcification process and exacerbate valve failure due to increased mechanical stress on the valve, activation of the renin-angiotensin system, and enhanced thrombus formation. Furthermore, elevated blood pressure interacts with prosthesis mismatch and paravalvular leak, jointly affecting valve durability. This review explores the impact of elevated blood pressure on bioprosthetic valve calcification and failure after TAVR, and emphasizes the importance of blood pressure control, optimized preoperative assessment, and appropriate valve selection in reducing valve failures.
Humans ; Transcatheter Aortic Valve Replacement/adverse effects* ; Calcinosis/etiology* ; Bioprosthesis ; Heart Valve Prosthesis/adverse effects* ; Prosthesis Failure ; Aortic Valve Stenosis/surgery* ; Aortic Valve/surgery* ; Hypertension/physiopathology*

OBJECTIVES: To evaluate the short-term clinical efficacy of transcatheter edge-to-edge repair (TEER) in patients with moderate to severe mitral regurgitation. METHODS: Clinical data of patients with moderate to severe mitral regurgitation who underwent TEER in the Department of Cardiology, the First Affiliated Hospital of Xi'an Jiaotong University from April 2021 to May 2024, were retrospectively analyzed, including preoperative baseline clinical and echocardiography data, intraoperative data and 6-month postoperative follow-up data. RESULTS: A total of 67 patients' (47 males and 20 females) data were included, of whom 62 completed 6-month follow-up. The immediately postoperative success rate was 88.1% (59/67), and 83.9% (52/62) patients exhibited mitral regurgitation ≤2+ at 6 months postoperatively, showing significant improvement compared with preoperative (P<0.05). The proportion of patients with mitral regurgitation ≤2+ at 6 months was significantly higher in the degenerative mitral regurgitation (DMR) group than that in the functional mitral regurgitation (FMR) group (P<0.05). The mean mitral valve gradient (MVG) in DMR group was increased from (3.1±1.2) mmHg (1 mmHg=0.133 kPa) to (3.7±1.2) mmHg 6 months after operation (P<0.05), while there was no significant change in FMR group (P>0.05). Compared with those before operation, the N-terminal pro-B-type natriuretic peptide levels in both FMR and DMR groups were significantly lower at 6 months postoperatively (all P<0.05), and the left atrial volume index and left atrial anteroposterior diameter were also significantly lower (all P<0.05). The left ventricular end-diastolic diameter and left ventricular end-systolic diameter were significantly reduced 6 months after operation in the FMR group (all P<0.05), but no significant changes were observed in the DMR group (all P>0.05). The ejection fraction was not significantly changed before and after operation in both groups (all P>0.05). The mitral regurgitation, tricuspid regurgitant, and pulmonary artery pressure were significantly reduced in both groups at 6 months postoperatively (all P<0.05). CONCLUSIONS TEER is effective for moderate to severe mitral regurgitation. The improve-ments in left ventricular remodeling are more pronounced in patients with FMR while the degree of mitral regurgitation is more significant in DMR patients. However, MVG elevation is more common during the follow-up.
Humans ; Mitral Valve Insufficiency/surgery* ; Male ; Female ; Retrospective Studies ; Middle Aged ; Aged ; Treatment Outcome ; Mitral Valve/surgery* ; Cardiac Catheterization/methods* ; Heart Valve Prosthesis Implantation/methods* ; Adult ; Follow-Up Studies