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

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.

In the past few decades, 3D-printed dental implants have been manufactured, and significant studies have demonstrated the pre-clinical validation of such systems. However, studies have yet to tackle the ever-present issue of preventing the jumping gap to enhance overall outcomes. The present study details the utilization of patient computed tomography (CT) data to design and subsequently fabricate a multi-component customized dental implant assembly and customized instruments using direct metal laser sintering (DMLS) technology. The workflow was validated for two patient data sets (cases 1 and 2), which were used to render and print custom implant assemblies; the simulation data for these were compared with a commercially available solution. The present study incorporated a prototype stage as well as subjecting the customized implant assemblies to both static (Case 1: 38.89-77.81 MPa vs 75.47-158.09 MPa; Case 2: 83.95-106.65 MPa vs 55.23-126.57 MPa) and dynamic finite element analysis (Case 1: 41.08-84.09 MPa vs 75.45-187.91 MPa; Case 2: 106.81-108.70 MPa vs 79.18-135.48 MPa) along with resonance frequency analysis (Case 1: 7763.2 Hz vs 7003.6 Hz; Case 2: 7910.1 Hz vs 7102.1 Hz) as well as residual stress analysis. The assembly's stress patterns and resonance frequencies were evaluated against a commercially available implant system. It was observed that the customized implant assemblies tended to outperform the commercially available solution in most simulated scenarios.

The formation of diabetic foot ulcers (DFU) is consequential of peripheral neuropathy, peripheral arterial disease and foot deformity, leading to altered foot biomechanics and plantar loads. Plantar load comprises of normal pressure and shear stress, however, there are currently no in-shoe devices capable of measuring both components. The STrain Analysis and Mapping of the Plantar Surface (STAMPS) system, developed at the University of Leeds, utilises Digital Image Correlation (DIC) to measure the strain captured by a plastically deformable insole, as a method to understand plantar load during gait. A 2D DIC software was used to capture cumulative plantar strain and displacement pointwise data, however this method was limited to the analysis of planar surfaces. To address this, 3D instrumentation and DIC methods have been developed and implemented into the STAMPS3D system, used as a tool to capture data that is representative of the non-planar nature of plantar surfaces of the foot. A case-study is used to demonstrate how STAMPS3D can measure multi-dimensional strain, bringing potential to improve clinical screening of DFU risk.

Muscle tissue is most frequently cut or separated in surgery. Waterjet as an emerging non-rigid cutting method is newly introduced into soft tissue dissection which shows a great potential in soft muscle cutting for low-trauma surgery. However, the cutting mechanisms of muscle material to waterjet impact remain unknown. This study reports the cutting responses of muscle tissue to waterjet impact. Waterjet morphology, depths of cut, cutting surface morphology and deformation of muscles were experimentally investigated using a computer-controlled waterjet machine. The mechanical properties of muscles were also measured to explore the property-processing relation. The conversion relationship between kinetic energy of waterjet and potential energy of muscle damage was established based on energy balance theory. Based on the experimental investigation and fracture mechanism analysis, the critical and the reasonable waterjet separation pressures for the muscles were respectively 0.8-1.1 MPa and 1.4-2.0 MPa for balancing separation efficiency and surrounding tissue protection. It was also found the muscle depth of cut under waterjet impact significantly increased with the impact pressure, but rapidly reduced with the increase in impact angle and transverse speed. In addition, a new phenomenon of swelling effect of the muscles was discovered in waterjet impact, which heavily affects the depths of cut. The proper stand-off distance was determined considering the muscle swelling effect and initial segment of waterjet. This research first provides practical insights into the process selection and quality control for waterjet cutting of soft muscles, advancing the clinical application of waterjet to muscle separation.