Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine最新文献

The prolonged whole-body vibration (WBV) may be one of the important factors contributing to low back pain. This study used a validated whole-body model and the WBV evaluation standard (ISO 2631-5:2018) to investigate the effects of car seat, frequency and age on the risk factors of the lumbar spine during prolonged exposure to WBV. The modal frequencies contributing more to the human resonance were first preliminarily predicted by modal analysis, and then sinusoidal excitations with frequencies of 1, 3, 5, 7, 9, 11 and 13 Hz were applied for transient analysis. On this basis, the adverse effects of long-term WBV on the lumbar spine were assessed based on the risk factors defined in the WBV evaluation standard (ISO 2631-5:2018). The transient analysis and risk factor calculation demonstrated that the responses exhibited a pronounced frequency dependence, with the highest response occurring at 4 Hz and 5 Hz excitation for elastic and rigid car seats, respectively. Rigid car seat increased disc von Mises stress and risk factors by 7.6% and 11%, respectively, compared with elastic one. After 5 years from the age of 25, the peak risk factors for human-body exposure to vibration were 0.73 and 0.81 for elastic and rigid car seats, respectively and continued to increase with age. From age 45 onwards, the adverse effects of vibration on the lumbar spine will reach a risk level considered dangerous after 5 years.

Arterial stenosis, resulting from plaque accumulation, can lead to serious conditions such as thrombosis and von Willebrand syndrome. This study investigates how variations in stenosis shape and severity affect red blood cell (RBC) and von Willebrand factor (VWF) damage through simulations and experimental approaches. A continuous flow generation device was utilized to create a blood circulation platform. The effects of different stenosis shapes and severities under continuous flow conditions on RBC damage and VWF degradation were examined. Blood samples were then analyzed for plasma-free hemoglobin concentration and VWF degradation. The results indicated that increased stenosis severity correlated with elevated hemolysis and a higher degradation rate of high molecular weight VWF (HMW-VWF). Rectangular stenosis induced more severe hemolysis and VWF degradation compared to elliptical stenosis at equivalent stenosis degrees. Both stenosis types demonstrated varying VWF degradation rates at low and medium/high stenosis levels, with elliptical stenosis showing particularly low VWF degradation at lower stenosis levels. The study highlights that different stenosis shapes and severities significantly affect blood damage under continuous flow. Greater stenosis severity resulted in increased blood flow velocity and wall shear stress (WSS), leading to enhanced hemolysis and VWF degradation, with rectangular stenosis showing more pronounced effects.

Hydroxyapatite (HA) is prevalently employed as a biomaterial, courtesy of its bone-like resemblance. For the purpose of counterbalancing the frail mechanical attributes of unadulterated HA, the creation of bioceramic composite materials has been instigated. The goal of this investigation revolves around the endeavor to encapsulate human teeth by utilizing a HA-based dental composite powder, procured from perlite in conjunction with zeolite obtained via hydrothermal synthesis methodologies. Human teeth were gathered from dental practitioners, underwent a calcination process at an exponentially high temperature of 850°C for three hours and subsequently transformed into a powdered state. Calcium nitrate (CaNO₃) was indispensable as the calcium supplier, while phosphorus pentoxide (P₂O₅) was pivotal as the source of phosphorus. Different proportions (10%-50%) of perlite-converted zeolite were incorporated into the artificially synthesized Hydroxyapatite (HA). The prepared specimens were later subjected to a series of tests, including Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), investigation of surface roughness, and in vitro analyses. For in vitro test, samples were submerged in Ringer's solution and kept for periods of 1, 10, and 25 days. It became evident that an escalation in reinforcement quantity triggered a concurrent rise in parameters such as porosity and surface roughness value. It was also noted that a HA layer had established itself on the surface of the specimens according to the Ca/P proportion. With an increase in time spent submerged in the solution, a corresponding increase was observed in apatite formation.

With the development of medical equipment technology, minimally invasive surgery has become the core advancement direction in surgical treatment. There are still some issues with mucosal marking and injection under gastrointestinal endoscopy. This paper aims to study a novel negative pressure electrocoagulation marking technique. Using a negative pressure pump in conjunction with a radiofrequency energy emission platform, we compared the effects of conventional electrocoagulation marking and negative pressure electrocoagulation marking using porcine stomachs as experimental subjects. The experimental system includes a negative pressure electrocoagulation platform and a radiofrequency energy emission platform. The experimental materials are fresh porcine stomachs. Electrocoagulation marking of porcine stomach under no negative pressure and negative pressure conditions. An infrared thermal imaging camera was used to measure the temperature. The experimental results showed that the highest average temperature in the no negative pressure group was 78.2 ± 7.6°C, while in the negative pressure group it was 78.1 ± 7.9°C, with no significant difference between the two (p = 0.8557). During subsequent injection tests, the average burst pressure in the no negative pressure group was 66.40 ± 16.96 mmHg, while in the negative pressure group it was 83.48 ± 28.56 mmHg. The negative pressure group had a significantly higher burst pressure (p = 0.0135), indicating that the negative pressure electrocoagulation marking technique can significantly enhance mucosal elevation. The results suggest that the negative pressure electrocoagulation marking technique has great potential for application in gastrointestinal endoscopic surgery. It can improve the safety of the surgery without increasing thermal injury, helping to reduce the incidence of intraoperative complications.

Orthopedic surgical robot systems increasingly demand high-precision positioning and orientation. Low accuracy of positioning and orientation is a potential hazard during a surgery and also affects the surgical quality. The transformation relationship between the robot base coordinate system and the optical tracking system, which is called hand-eye calibration, is supposed to be calibrated accurately preoperatively. The hand-eye parameters identification is inevitably affected by the errors of robot kinematic parameters. Errors in robot kinematic parameters and hand-eye parameters significantly influence the accuracy of an orthopedic surgical robot system. To enhance the calibration accuracy, a simultaneous precise calibration method of the robot's kinematic parameters and hand-eye parameters for orthopedic surgical robot systems is proposed, eliminating the error accumulation caused by a step-by-step calibration procedure of hand-eye parameters and kinematic parameters. The objective function of the proposed simultaneous calibration method is defined as the weighted sum of the averages and variances of the positioning and orientation errors of the robot's end-effector, ensuring the difference between the errors of the robot poses after parameters calibration in its work space is small, and it is solved by using the Differential Evolution algorithm, avoiding complex gradient calculations. The proposed calibration method is verified by experiments, and a robot-assisted osteotomy experiment is also conducted to demonstrate the accuracy and effectiveness of the proposed calibration method.

To ensure the long-term success of temporomandibular joint (TMJ) implants, it is imperative to understand their biomechanical performances. This study aims to compare the biomechanical performance of two stock implants (narrow and standard) under unilateral and bilateral clenching during both osseointegrated and non-osseointegrated conditions. Finite element models of a human mandible were developed from QCT data, with the left TMJ being replaced by the implants. Six clenching tasks were simulated to evaluate stress and strain distributions in the mandible and implants. Ipsilateral clenching produced higher mandibular strains, while contralateral clenching generated larger implant stresses. Furthermore, intercuspal biting was found to have produced the highest strain (1750-1880 µε) and stress (∼17 MPa) in the mandible. Osseointegration reduced stresses (up to 0.14 MPa) and strains (up to 30 µε) in mandible as well as stresses in mandibular components (up to 48 MPa) and screws (up to 71 MPa). However, during non-osseointegrated conditions, stresses in cortical bone were higher for standard TMJ implant as compared to narrow implant. This suggests possible preference of narrow implant over standard ones.

Instabilities of the upper body affect posture and locomotion in people with Parkinson's disease (PD), but the responses of the torso to sudden perturbations have not yet been investigated. This study aimed to examine upper body stability using a wobbling seat encountering challenging perturbations in comparison to healthy age-matched controls. In this cross-sectional study, 12 people with PD and 12 healthy individuals sat on a wobbling seat and underwent quick release perturbations. Motion capture was used to assess upper body stability based on the kinematic data of sways in all directions. People with PD had greater upper body sways than the control group in all directions when faced with unexpected perturbations. The application of expected perturbations to people with PD caused approximately 2.4 times greater upper body sways in the flexion direction (p < 0.001). Maximum sway velocity was significantly greater (p = 0.001) and time-to-fall was significantly shorter (p = 0.004) in people with PD than in the control cohort. People with PD had upper body instability, specifically in the forward direction. They were unable to adapt their neuromuscular responses after repeated trials. Given the significance of upper body stability in performing daily physical activities, it is imperative to consider long-term trunk rehabilitation for people with PD.

Osteoporosis compromises bone strength, making bone more susceptible to fractures. Decreased bone density heightens susceptibility to femoral neck fractures. The study investigated the impact of bone density on implant performance across three categories of bone quality: healthy, osteopenic, and osteoporotic. The effectiveness of three commonly used implant types (Femoral Neck System, Dynamic Condylar Screw, and Dynamic Hip Screw, where later two equipped with an anti-rotational screw) was evaluated through finite element analysis for treating Pauwels type III fracture. The bone geometry and material properties were based on a subject-specific CT data. The density and Young's modulus of bone elements were adjusted to simulate osteopenic and osteoporotic bone. FE models were developed and the peak loading values for normal walking and stair climbing conditions were considered. Stability and performance of the implant were assessed using bone strain, implant stress, deformation and rotation of the femoral head, micromotion at the interfaces, strain shielding, and risk of implant cut-out. Except for DCS with AR-screw and FNS implants under stair climbing conditions in weaker bone qualities, the implant stress remained within the yield limit of Ti-alloy. The comprehensive assessment identified DHS2 as the preferred implant option for treating such fractures, even in poor bone quality. The risk of cut-out risk was up to 3.9% higher in DCS2 and 6.3% higher in FNS implanted models than in DHS2. The effect of change in bone quality was comparatively less in DHS2 implants than the other two types.

Lumbar degenerative disc diseases (DDDs) are the common causes of low back pain, leading to non-conservative treatments like fusion and non-fusion surgery as a last resort. Fusion surgery is the gold standard for addressing DDDs, where implants such as cages, pedicle screws and rods are used for posterior stabilization. Various finite element (FE) studies have reported using corrugated cage surface textures; some others have used flat textures for virtual implantation. No comparative studies have been reported on the biomechanical effects of fusion surgery under implantation with cages of varying surface textures. The present biomechanical study compares the mechanical behaviour of an L4-L5 segment implanted with cages of different surface textures. The surgical techniques used for implantation are posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion. The virtual surgical models were developed from a previously validated intact lumbar spine FE model and simulated for physiological loading conditions. Compared to the flat cage implantation, a higher magnitude of stress was experienced by the cages and pedicle screw-rod systems under corrugated cage implantation. The maximum von Mises stress generated in the PLIF corrugated cage was 80.69% more than that observed in the flat cage. The maximum stresses in the corrugated cage were higher than those of the flat cage by 38.43%-80.69%, considering all the applied loading conditions. The findings of the study suggest that corrugated cage surface texture and suitable material selection may help in improving the long-term stability of cages.

This systematic review and meta-analysis evaluated the effectiveness of virtual reality (VR) rehabilitation in improving functional performance for patients with cervical spinal cord injury (CSCI), which affects both upper and lower limb function. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, electronic databases including PubMed, Medline, Embase, Scopus, and Cochrane Library were searched. Meta-analysis was conducted on studies reporting common functional outcomes, with standardized mean difference (SMD) used to quantify effect sizes. Nine studies were included in the systematic review, and seven were analyzed in the meta-analysis. Three studies focused on upper limb outcomes, and six on lower limb function. Of the seven studies, four included only CSCI patients, while three had mixed injury cohorts (cervical and thoracic). Meta-analysis revealed no statistically significant improvements in function for mixed injury cohorts across various outcomes: Timed-Up and Go test (SMD 0.94 [-0.21, 2.09]), Berg Balance Scale (-0.83 [-1.72, 0.07]), Walking Index for Spinal Cord Injury II (-0.38 [-0.86, 0.09]), Spinal Cord Independence Measure (-0.41 [-0.92, 0.10]), and 10 Meter Walk Test (-1.43 [-3.58, -0.73]). However, the Timed-Up and Go test showed significant results favoring VR-based rehabilitation when excluding mixed cohorts (SMD 2.02 [1.24, 2.79]). VR rehabilitation shows promise for improving lower limb function in CSCI patients, but overall evidence remains inconclusive due to study variability. Standardizing outcome measures and further research on upper limb rehabilitation are essential to enhance the impact of VR-based interventions for CSCI.