Strategies in surface engineering for the regulation of microclimates in skin-medical product interactions.

There is a growing number of personal healthcare devices that are in prolonged contact with the skin. The functionality of these products is linked to the interface formed by the contact between the medical apparatus and the skin. The interface can be characterised by its topology, compliance, and moisture and thermal regulating capabilities. Many devices are, however, described to have suboptimal and occlusive contacts, resulting in physiological unfavourable microclimates at the interface. The resulting poor management of moisture and temperature can impact the functionality and utility of the device and, in severe cases, lead to physical harm to the user. Being able to control the microclimate is therefore expected to limit medical-device related injuries and prevent associated skin complications. Surface engineering can modify and potentially enhance the regulation of the microclimate factors surrounding the interface between a product's surface and the skin. This review provides an overview of potential engineering solutions considering the needs for, and influences on, regulation of temperature and moisture by considering the skin-medical device interface as a system. These findings serve as a platform for the anticipated progress in the role of surface engineering for skin-device microclimate regulation.

Bone fixation techniques for managing joint disorders and injuries: A review study.

The majority of surgical procedures treating joint disorders require a technique to realize a firm implant-to-tissue and/or a tissue-to-tissue fixation. Fixation methods have direct effects on survival, performance and integration of orthopedic implants This review paper gives an overview of novel fixation techniques that have been evaluated and optimized for orthopaedic joint implants and could be alternatives for traditional implant fixation techniques or inspirations for future design of joint implantation procedures. METHOD: The articles were selected using the Scopus search engine. Key words referring to traditional fixation methods have been excluded to find potential innovative fixation techniques. In order to review the recent anchorage systems, only articles that been published during the period of 2010-2020 have been included. RESULTS: A total of 57 studies were analyzed. The result revealed that three main fixation principles are being employed: using mechanical interlockings, employing adhesives, and performing tissue-bonding strategies. CONCLUSION: The development of fixation techniques demonstrates a transformation from the general anchoring tools like K-wires toward application-specific designs. Several new methods have been designed and evaluated, which highlight encouraging results as described in this review. It seems that mechanical fixations provide the strongest anchorage. Employing (bio)-adhesives as fixation tool could revolutionize the field of orthopedic surgery. However, the adhesives must be improved and optimized to meet the requirements of an anchorage system. Long-term fixation might be formed by tissue ingrowth approaches which showed promising results. In most cases further clinical studies are required to explore their outputs in clinical applications.

Halo pin positioning in the temporal bone; parameters for safe halo gravity traction.

INTRODUCTION: Halo gravity traction (HGT) is increasingly used pre-operatively in the treatment of children with complex spinal deformities. However, the design of the current halo crowns is not optimal for that purpose. To prevent pin loosening and to avoid visual scars, fixation to the temporal area would be preferable. This study aims to determine whether this area could be safe for positioning HGT pins. METHODS: A custom made traction setup plus three human cadaver skulls were used to determine the most optimal pin location, the resistance to migration and the load to failure on the temporal bone. A custom-made spring-loaded pin with an adjustable axial force was used. For the migration experiment, this pin was positioned at 10 predefined anatomical areas in the temporal region of adult cadaver skulls, with different predefined axial forces. Subsequently traction force was applied and increased until migration occurred. For the load-to-failure experiment, the pin was positioned on the most applicable temporal location on both sides of the skull. RESULTS: The most optimal position was identified as just antero-cranial to the auricle. The resistance to migration was clearly related to the axial tightening force. With an axial force of only 100 N, which corresponds to a torque of 0.06 Nm (0.5 in-lb), a vertical traction force of at least 200 N was needed for pin migration. A tightening force of 200 N (torque 0.2 Nm or 2 in-lb) was sufficient to resist migration at the maximal applied force of 360 N for all but one of the pins. The load-to-failure experiment showed a failure range of 780-1270 N axial force, which was not obviously related to skull thickness. CONCLUSION: The temporal bone area of adult skulls allows axial tightening forces that are well above those needed for HGT in children. The generally applied torque of 0.5 Nm (4 in-lb) which corresponds to about 350 N axial force, appeared well below the failure load of these skulls and much higher than needed for firm fixation.

Influence of cast change interval in the Ponseti method: A systematic review.

BACKGROUND: Clubfeet are commonly treated using the Ponseti method. This method involves weekly manipulation and casting which gradually corrects the position of the foot. However, the reasons for following a weekly interval are not clear. QUESTION / PURPOSE: The aim is to investigate the influence of the cast change interval on treatment outcomes in the Ponseti method. METHODS: We performed a systematic review of comparative studies in which the cast change interval was varied. Scientific databases were searched for relevant publications, screened for eligibility and assessed for a risk of bias. A 'best evidence' synthesis tool was used to synthesize the results of the included studies and draw conclusions from relevant clinical outcomes. RESULTS: Nine papers matched the inclusion criteria, which provided data of 587 subjects who had a total of 870 clubfeet. There is strong evidence for a positive relation between cast change interval and treatment duration. However, there is no evidence for any relation between the cast change interval and the required number of casts, tenotomy rate, required surgery or failure rate. CONCLUSIONS: Accelerated versions are as effective and safe as the traditional Ponseti method. However, more research is needed to assess the long-term results and to identify an optimal cast change interval.

Quantifying the Ponseti method.

The Ponseti method is the accepted treatment of idiopathic clubfoot. Although the method of manipulating the baby feet is described in great detail, current study aimed to investigate the magnitude and course of the applied forces in order to optimise the treatment of clubfoot. An instrumented clubfoot model was constructed with force sensors on the location of the first metatarsal (FM) and the talar neck (TN) and treated with the Ponseti method by 17 practitioners. Applied forces on FM and TN were measured during manipulation (4.2N; 12N), during casting (3.2N; 3.5N) and after casting (2.9N; 2.2N). The forces during manipulation were significantly higher than during casting on TN (p<0.001) but not on FM (p=0.129). No 'correct' amount of force could be determined and inter-practitioner variability was measured to be 70%. The resulting pressure of the cast on the clubfoot model as measured directly after casting was significantly higher than local tissue perfusion. The results of this study suggest potential for the optimisation of the application of the Ponseti method.

Risk factors for falls of older citizens.

OBJECTIVE: Fall prevention is a major issue in the ageing society. This study provides an overview of all risk factors for falls of older citizens. METHOD: A literature search was conducted to retrieve studies of the past 25 years. All participants from the studies lived in the community or institutions and were aged 60 or older. The following key word combinations were used, limited to the title: elderly or older people or older adults and fall and risk. The risk factors were categorised as relevant and amendable, relevant but non amendable, inconclusive or unsupported. RESULTS: In total 30 publications were studied in 2013 in Enschede, the Netherlands. The relevant intrinsic risk factors are muscle strength, balance capacity, reactive power, dual tasking and sleep disturbance. Relevant extrinsic risk factors are home hazards, wrong use of assistive devices and bad footwear. Behaviour-related risk factors are hurrying, risk taking, physical inactivity and fear of falling. Relevant symptoms that could be caused by underlying risk factors are mobility problems, gait problems, vertigo, use of assisting devices and history of falls. CONCLUSIONS: Several risk factors are determined to be relevant and amendable. The provided overview could be used to create fall preventive measures for elderly.

Mechanical behavior of a novel non-fusion scoliosis correction device.

INTRODUCTION: We developed an innovative non-fusion correction system (XS LATOR) consisting of two individual implants that are extendable and extremely flexible. One implant, the XS LAT, generates a lateral, bending moment and one implant, the XS TOR, generates a torsion moment. Two 'inverse' implants were developed for generating torsion and lateral bending in a porcine model was tested for force delivery. An in vitro experiment was set up to describe the mechanical behavior of both implants. MATERIALS AND METHODS: Narrow and wide ('inverse') versions of the XS TOR and XS LAT were mounted on an apparatus that was able to simulate different spinal geometries. The implants were anchored to three artificial vertebrae with integrated 6D force sensors, after which the vertebrae were rotated and translated towards the demanded position. The reaction forces and moments were recorded in all configurations. The maximal (lateral) bending moment, which occurred at the middle vertebra, was determined and, similarly, torque applied at the center of rotation of the middle vertebra was calculated. RESULTS: As expected, the wide and the small versions of the XS TOR generate a torque that increases during the growth of the system. Similarly, the XS LAT generates a bending moment that slightly increases during the growth of the system. The produced moments approximate the theoretically predicted ones. The contribution to the spinal stiffness ranges between 0.01Nm/° and 0.04Nm/° in bending and between 0.03Nm/° and 0.08Nm/° in torsion. CONCLUSIONS: The XS TOR and the XS LAT are able to generate a torque and a bending moment that remain (fairly) constant during spinal growth when a shape change due to the generated moment/torque is achieved. The stiffness of the implants is extremely low, being only a fraction of the stiffness of conventional, spinal fusion constructs. Current fusion systems, such as non-segmental spinal constructs generally, have 11 times higher stiffness in torsion and 6 times higher stiffness in lateral bending. Implantation of the XS LATOR adds 9% stiffness in axial rotation and 17% stiffness in lateral bending (to the original spinal stiffness). By preserving the flexibility of the spine after implantation, fusion of the vertebrae in the instrumented region is likely to be prevented.

Modeling of WalkMECH: a fully-passive energy-efficient transfemoral prosthesis prototype.

In this paper we present the port-based model of WalkMECH, a fully-passive transfemoral prosthesis prototype that has been designed and realized for normal walking. The model has been implemented in a simulation environment so to analyze the performance of the prosthetic leg in walking experiments and so to enhance the mechanics of the system. The accuracy of the model has been validated by experimental tests with a unilateral amputee participant.

Design of a fully-passive transfemoral prosthesis prototype.

In this study, we present the mechanical design of a prototype of a fully-passive transfemoral prosthesis for normal walking. The conceptual working principle at the basis of the design is inspired by the power flow in human gait, with the main purpose of realizing an energy efficient device. The mechanism is based on three elements, which are responsible of the energetic coupling between the knee and ankle joints. The design parameters of the prototype are determined according to the human body and the natural gait characteristics, in order to mimic the dynamic behavior of a healthy leg. Hereby, we present the construction details of the prototype, which realizes the working principle of the conceptual mechanism.

The effect of three-dimensional geometrical changes during adolescent growth on the biomechanics of a spinal motion segment.

During adolescent growth, vertebrae and intervertebral discs undergo various geometrical changes. Although such changes in geometry are well known, their effects on spinal stiffness remains poorly understood. However, this understanding is essential in the treatment of spinal abnormalities during growth, such as scoliosis. A finite element model of an L3-L4 motion segment was developed, validated and applied to study the quantitative effects of changing geometry during adolescent growth on spinal stiffness in flexion, extension, lateral bending and axial rotation. Height, width and depth of the vertebrae and intervertebral disc were varied, as were the width of the transverse processes, the length of the spinous process, the size of the nucleus, facet joint areas and ligament size. These variations were based on average growth data for girls, as reported in literature. Overall, adolescent growth increases the stiffness with 36% (lateral bending and extension) to 44% (flexion). Two thirds of this increase occurs between 10 and 14 years of age and the last third between 14 years of age and maturity. Although the height is the largest geometrical change during adolescent growth, its effect on the biomechanics is small. The depth increase of the disc and vertebrae significantly affects the stiffness in all directions, while the width increase mainly affects the lateral bending stiffness. Hence, when analysing the biomechanics of the growing adolescent spine (for instance in scoliosis research), the inclusion of depth and width changes, in addition to the usually implemented height change, is essential.