Pancreatic anastomosis training models: Current status and future directions.

Postoperative pancreatic fistula (POPF) is a major cause of morbidity and mortality after pancreatoduodenectomy (PD), and previous research has focused on patient-related risk factors and comparisons between anastomotic techniques. However, it is recognized that surgeon experience is an important factor in POPF outcomes, and that there is a significant learning curve for the pancreatic anastomosis. The aim of this study was to review the current literature on training models for the pancreatic anastomosis, and to explore areas for future research.

A Hybrid Method Integrating A Musculoskeletal Model with Long Short-Term Memory (LSTM) for Human Motion Prediction.

So far, it shows a growing interest in the biomechanics community in the development of wearable technologies and their clinical applications, which enables the diagnosis of movement disorders and design of the rehabilitation interventions. To provide reliable feedback in the human-machine interface for advanced rehabilitation devices, methods to predict motion intention was developed which aim to generate future human motion based on the measured motion. An inertial measurement unit (IMU) is a promising device for motion tracking, with the advantages of low cost and high convenience in sensor placement to measure motion in almost every environment.

In vitro investigation into the forces involved during lipofilling.

Breast augmentation using implants is the most common aesthetic and reconstructive breast surgical procedure. Complications such as implant rupture maybe related to surgical technique and damage to the implant. Autologous fat transfer (lipofilling) using metallic cannulae has become a standard adjunctive, yet there is little evidence on lipofilling safety in the presence of implants.

Design of an improved surgical instrument for the removal of bladder tumours.

The aim of this work was to design an add-on instrument that could potentially decrease the recurrence of non-muscle invasive bladder cancer. The current surgical approach permits spilled tumour cells to disseminate within the bladder, re-implant and cause tumour recurrence. An add-on instrument has been designed in the form of an opening cone intended to provide space for surgery and yet reduce tumour cell spillage and dissemination.

Wear of the Charité® lumbar intervertebral disc replacement investigated using an electro-mechanical spine simulator.

The Charité(®) lumbar intervertebral disc replacement was subjected to wear testing in an electro-mechanical spine simulator. Sinusoidally varying compression (0.6-2 kN, frequency 2 Hz), rotation (±2°, frequency 1 Hz), flexion-extension (6° to -3°, frequency 1 Hz) and lateral bending (±2°, frequency 1 Hz) were applied out of phase to specimens immersed in diluted calf serum at 37 °C.

Assessment of non-contacting optical methods to measure wear and surface roughness in ceramic total disc replacements.

This study presents a method for measuring the low volumetric wear expected in ceramic total disc replacements, which can be used to replace intervertebral discs in the spine, using non-contacting optical methods. Alumina-on-alumina ball-on-disc tests were conducted with test conditions approximating those of cervical (neck region of the spine) total disc replacement wear tests. The samples were then scanned using a three-dimensional non-contacting optical profilometer and the data used to measure surface roughness and develop a method for measuring the wear volume.

Variation in viscoelastic properties of bovine articular cartilage below, up to and above healthy gait-relevant loading frequencies.

The aim of this study was to determine the variation in viscoelastic properties of femoral head bovine articular cartilage, on-bone, over five orders of magnitude of loading frequency. These frequencies ranged from below, up to and above healthy gait-relevant frequencies, using<1, 1-5 and 10 Hz, respectively. Dynamic mechanical analysis was used to measure storage and loss stiffness.

Viscoelastic properties of bovine knee joint articular cartilage: dependency on thickness and loading frequency.

Background: The knee is an incongruent joint predisposed to developing osteoarthritis, with certain regions being more at risk of cartilage degeneration even in non-osteoarthrosed joints.At present it is unknown if knee regions prone to cartilage degeneration have similar storage and/or loss stiffness, and frequency-dependent trends, to other knee joint cartilage. The aim of this study was to determine the range of frequency-dependent, viscoelastic stiffness of articular cartilage across the bovine knee joint.

Effect of lubricants on friction in laboratory tests of a total disc replacement device.

Some designs of total disc replacement devices have articulating bearing surfaces, and these devices are tested in vitro with a lubricant of diluted calf serum. It is believed that the lubricant found in total disc replacement devices in vivo is interstitial fluid that may have properties between that in Ringer's solution and diluted calf serum. To investigate the effect of lubricants, a set of friction tests were performed on a generic model of a metal against metal ball-and-socket total disc replacement device.

Wear in metal-on-metal total disc arthroplasty.

The wear of a model metal-on-metal ball-and-socket total disc arthroplasty was measured in a simulator. The ball had a radius of 10 mm, and there was a radial clearance between ball and socket of 0.015 mm.

A biomechanical study of the Birmingham mid head resection arthroplasty: effect of stem size on femoral neck fracture.

The Birmingham mid head resection (BMHR) arthroplasty can be used as an alternative to conventional stemmed total hip arthroplasty in young patients unsuitable for hip resurfacing. This study investigated the effect of stem size on femoral neck fracture in the BMHR. Sawbones composite femurs were randomly allocated to one of the following groups: (1) unprepared femur with no prosthesis, (2) femur prepared with a Birmingham hip resurfacing (BHR) prosthesis, (3) femur prepared with a BMHR stem size 1 (BMHR-1) and (4) femur prepared with a BMHR stem size 3 (BMHR-3).

In vitro investigation of friction at the interface between bone and a surgical instrument.

This study investigated the friction between surgical instruments and bone to aid improvements to instrument design. The bases of orthopaedic surgical instruments are usually made of metal, especially stainless steel. Silicone elastomer was chosen as an alternate biocompatible material, which would be compliant on the bone surface when used as the base of an instrument.

Applicability of sheep and pig models for cancellous bone in human vertebral bodies.

The mineral content of cancellous bone from sheep and pig vertebral bodies was determined by ashing at 800 degrees C. The results were compared with published results for human vertebral cancellous bone. The results for sheep (0.

Investigation of techniques for the measurement of articular cartilage surface roughness.

Articular cartilage is the bearing surface of synovial joints and plays a crucial role in the tribology to enable low friction joint movement. A detailed understanding of the surface roughness of articular cartilage is important to understand how natural joints behave and the parameters required for future joint replacement materials. Bovine articular cartilage on bone samples was prepared and the surface roughness was measured using scanning electron microscopy stereoscopic imaging at magnifications in the range 500× to 2000×.

Evaluation of a transient, simultaneous, arbitrary Lagrange-Euler based multi-physics method for simulating the mitral heart valve.

A transient multi-physics model of the mitral heart valve has been developed, which allows simultaneous calculation of fluid flow and structural deformation. A recently developed contact method has been applied to enable simulation of systole (the stage when blood pressure is elevated within the heart to pump blood to the body). The geometry was simplified to represent the mitral valve within the heart walls in two dimensions.

Polymer-on-metal or metal-on-polymer total disc arthroplasty: does it make a difference?

Study Design: Mechanical testing of total disc arthroplasty (TDA).

Objective: To compare the friction between a polymer socket-on-metal ball and metal socket-on-polymer ball TDA.

Summary Of Background Data: A degenerate intervertebral disc can be replaced by TDA.

Development of a transient large strain contact method for biological heart valve simulations.

A new 2D method to implement transient contact using Comsol Multiphysics (finite element analysis software that enables multiphysics simulations) is described, which is based on Hertzian contact. This method is compared to the existing (default) contact method that does not enable real transient simulations, but instead performs steady-state solutions where time is a constant. The two types of contact modelling have been applied to simple 2D biological heart valve models, undergoing strains in the region of 10% under 20 kPa pressure (applied over 0.

Effect of axial load on the flexural properties of an elastomeric total disc replacement.

Study Design: Twelve Cadisc-L devices were subjected to flexion (0°-6°) and extension (0° to -3°) motions at compressive loads between 500 N and 2000 N at a flexural rate between 0.25°/s and 3.0°/s.

Friction in metal-on-metal total disc arthroplasty: effect of ball radius.

Total disc arthroplasty (TDA) can be used to replace a degenerated intervertebral disc in the spine. There are different designs of prosthetic discs, but one of the most common is a ball-and-socket combination. Contact between the bearing surfaces can result in high frictional torque, which can then result in wear and implant loosening.

The effect of screw insertion angle and thread type on the pullout strength of bone screws in normal and osteoporotic cancellous bone models.

Screw fixation can be extremely difficult to achieve in osteoporotic (OP) bone because of its low strength. This study determined how pullout strength is affected by placing different bone screws at varying angles in normal and OP bone models. Pullout tests of screws placed axially, and at angles to the pullout axis (ranging from 10° to 40°), were performed in 0.

Viscoelastic properties of bovine articular cartilage attached to subchondral bone at high frequencies.

Background: Articular cartilage is a viscoelastic material, but its exact behaviour under the full range of physiological loading frequencies is unknown. The objective of this study was to measure the viscoelastic properties of bovine articular cartilage at loading frequencies of up to 92 Hz.

Methods: Intact tibial plateau cartilage, attached to subchondral bone, was investigated by dynamic mechanical analysis (DMA).

Compressive properties of commercially available polyurethane foams as mechanical models for osteoporotic human cancellous bone.

Background: Polyurethane (PU) foam is widely used as a model for cancellous bone. The higher density foams are used as standard biomechanical test materials, but none of the low density PU foams are universally accepted as models for osteoporotic (OP) bone. The aim of this study was to determine whether low density PU foam might be suitable for mimicking human OP cancellous bone.

Strength of wired sternotomy closures: effect of number of wire twists.

The objective of this study was to investigate the effect of the number of wire twists on the strength of wired sternotomy closures. A custom-built test rig, fitted to a materials testing machine, was used to apply an increasing tension to wire closures, until they failed. The number of twists in the wire closure was varied between one and ten.

Effect of mitral valve geometry on valve competence.

The aim of the investigation was to vary certain geometrical features of the mitral valve in vitro, in order to understand their role in valve function. Geometrical changes to mitral valve components are known to affect valve function, but complete understanding of how geometrical changes influence valve function is far from complete. Test apparatus has been used to apply pressure to porcine mitral valves.