Usability engineering in practice: developing an intervention for post-stroke therapy during a global pandemic.

This paper provides an overview of the usability engineering process and relevant standards informing the development of medical devices, together with adaptations to accommodate situations such as global pandemics where use of traditional face-to-face methods is restricted. To highlight some of those adaptations, a case study of a project developing a novel electronic rehabilitation device is referenced, which commenced in November 2020 amidst the COVID-19 pandemic. The Sheffield Adaptive Patterned Electrical Stimulation (SHAPES) project, led by Sheffield Teaching Hospitals NHS Foundation Trust (STH), aimed to design, manufacture and trial an intervention for use to treat upper arm spasticity after stroke. Presented is an outline and discussion of the challenges experienced in developing the SHAPES health technology intended for at-home use by stroke survivors and in implementing usability engineering approaches. Also highlighted, are the benefits that arose, which can offer easier involvement of vulnerable users and add flexibility in the ways that user feedback is sought. Challenges included: restricted travel; access to usual prototyping facilities; social distancing; infection prevention and control; availability of components; and changing work pressures and demands. Whereas benefits include: less travel; less time commitment; and greater scope for participants with restricted mobility to participate in the process. The paper advocates a more flexible approach to usability engineering and outlines the onward path for development and trialling of the SHAPES technology.

Interpretation of the scarf osteotomy by 10 surgeons.

BACKGROUND: The study compared three-dimensional (3D) changes in geometry of the first metatarsal following scarf osteotomy performed on standardised Sawbone® models by consultant foot and ankle surgeons. The study considered the inter-surgeon variances in interpretation and performance of the scarf osteotomy with respect to intra-surgeon variances. METHODS: The analysis used an accurate digitising system to measure and record points on the Sawbone® models in 3D space. Computer software performed vector analysis to calculate 3D rotations and translations of the first metatarsal head as well as the inter-metatarsal angle. Bone cut lengths and displacements were measured using a digital Vernier caliper. One surgeon performed the osteotomy 10 times to form an intra-surgeon control dataset, while 10 different surgeons each did one scarf osteotomy to form an inter-surgeon test dataset. RESULTS: Both surgical groups produced reductions in the 3D inter-metatarsal angle with non-significant differences between the groups (p>0.05). In contrast, the test group demonstrated highly significant (p=0.000) greater variance compared with the control dataset for all of the variables associated with surgical technique. In addition, there were highly significant (p=0.02 and 0.002) greater variances in the interpretation of the degree to which the metatarsal head should be translated medially (X) and inferiorly (Z). There was also a significant (p=0.001) increase in variances in the rotations about the dorsi/plantar-flexion (X) axis. The only significant differences (all p=0.000) attributable solely to differences in mean values were in proximal-distal (Y) translation, pronation (Y) rotation and medial (Z) rotation. The test group applied greater medial and plantar-flexion rotation of the metatarsal head than the control surgeon and significantly less (p=0.000) shortening of the first metatarsal than the control surgeon. CONCLUSIONS: The results of this geometric study demonstrate the versatility of the scarf osteotomy. As a result of the multi-planar nature of the osteotomy, there is a potential risk of producing unintended rotational mal-unions in all three planes. These rotational mal-unions may account for some of the poorer outcomes documented within the literature.

Custom-made 3D printed masks for children using non-invasive ventilation: a comparison of 3D scanning technologies and specifications for future clinical service use, guided by patient and professional experience.

Non-invasive ventilation (NIV) is assisted mechanical ventilation delivered via a facemask for people with chronic conditions that affect breathing. Mass-produced masks are available for both the adult and paediatric markets but masks that fit well are difficult to find for children who are small or have asymmetrical facial features. A good fit between the mask and the patient's face to minimise unintentional air leakage is essential to deliver the treatment effectively. We present an innovative use of 3D assessment and manufacturing technologies to deliver novel custom-made facemasks for children for whom a well-fitting standard mask is not available. This paper aims to describe the processes undertaken to investigate and compare currently available technologies for 3D scanning children and to explore the design of a system for creating custom-made paediatric NIV masks within the NHS. The paper therefore considers not only the quality and accuracy of the data, but also other factors such as the time and ease of process. Searches for all currently available scanning technologies were made. Photogrammetry image stitch using a smartphone and a digital camera, and two structured light scanners were selected and compared in the laboratory, in discussion with user groups, and in adult volunteers. Using the processes described, it became apparent that the optimal 3D scanning system for this purpose was the handheld structured light scanner. This option offered both superior accuracy and convenience and was more cost effective.

Fit for purpose? A cross-sectional study to evaluate the acceptability and usability of HeadUp, a novel neck support collar for neurological neck weakness.

The HeadUp collar (previously known as the Sheffield Support Snood) provides support for neck weakness caused by amyotrophic lateral sclerosis (ALS) and has shown to be superior to alternative options in a small cohort of patients from one single center. Here we report the assessment of the HeadUp collar in a larger cohort of patients, exploring the use in other neurological conditions and expanding to other centers across the UK and Ireland. An interventional cross-sectional study design was implemented to investigate the usability and acceptability of the HeadUp collar. A total of 139 patients were recruited for the study, 117 patients had a diagnosis of ALS and 22 patients presented with neck weakness due to other neurological conditions. Participants were assessed at baseline, fitted a HeadUp collar and followed-up one month later. The performance of the HeadUp collar was rated favorably compared to previously worn collars in terms of the ability to eat, drink and swallow. Findings suggest that the collar also permitted a more acceptable range of head movements whilst maintaining a good level of support. We conclude that the HeadUp collar is a suitable option for patients with neck weakness due to ALS and other neurological conditions.

Custom-made 3D printed masks for children using non-invasive ventilation: a feasibility study of production method and testing of outcomes in adult volunteers.

Non-invasive ventilation (NIV) is assisted mechanical ventilation delivered via a facemask for people with chronic conditions that affect breathing. NIV is most commonly delivered via an interface (mask) covering the nose (nasal mask) or the nose and mouth (oronasal mask). The number of children in the UK requiring NIV is currently estimated to be around 5000. Mass-produced masks are available for both the adult and paediatric markets but masks that fit well are difficult to find for children who are small or have asymmetrical facial features. A good conforming fit between the mask and the patient's face to minimise unintentional air leakage is essential to deliver the treatment effectively; most ventilators will trigger an alarm requiring action if such leakage is detected. We present an innovative use of 3D scanning and manufacturing technologies to deliver novel mask-face interfaces to optimise mask fit to the needs of individual patients. Ahead of planned user trials with paediatric patients, the project team trialled the feasibility of the process of creating and printing bespoke masks from 3D scan data and carried out testing of the masks in adult volunteers to select the strongest design concept for the paediatric trial. The evaluation of the process of designing a bespoke mask from scan data, arranging for its manufacture and carrying out user testing has been invaluable in gaining knowledge and discovering the pitfalls and timing bottlenecks in the processes. This allowed the team to iteratively refine the techniques and methods involved, informing user trials later on in the project. It has also provided indicative cost estimates for 3D printed mask prototype components which are useful in project decision making and trial planning. The value of the process extends to considerations for future implementation of the process within a clinical pathway.

An engineering approach towards a more discrete and efficient urinary drainage system.

Modern urinary catheter-to-leg-bag systems suffer from a number of shortcomings. Drainage tubing of current urinary leg bags is perceived as unnecessarily bulky compared to the indwelling catheters to which it is connected, and catheter designs are prone to the formation of biofilms, leading ultimately to encrustation and blocking. We used analytical and experimental engineering methodologies, aligned with current international (International Standards Organisation) and European standards, to optimise drainage tube size and flow efficiency and characterise tube kinking behaviour. Using computational fluid dynamics, we studied the influence of modern Foley catheter design on urodynamics and explored its potential influence on biofilm formation and encrustation. Results indicate that tubing diameters could be reduced by 40%-50% and still satisfy current International Standards Organisation flow rate standards for leg bags; this might also reduce the likelihood of tube kinking. The computational study showed how current catheter design may promote the development of lower velocity recirculating flows and high shear in proximity of regions known to be affected by bacterial adhesion and biofilm formation. If confirmed, these findings will give manufacturers greater flexibility to develop less obtrusive and more encrustation-resistant products for end users.

Three-dimensional analysis of different first metatarsal osteotomies in a hallux valgus model.

BACKGROUND: This study evaluates and compares three-dimensional (3-D) changes in geometry of the first metatarsal (MT1) independent of soft tissue corrections of 5 common osteotomies: three distal (Chevron, Mitchell, and Wilson), one proximal (Stephens basal), and one combined proximal/distal (Scarf), using standardized synthetic bone models. MATERIALS AND METHODS: A digitizing system was used to measure and record points on the synthetic bone models in 3-D space. Computer vector analysis calculated 3-D rotations and translations of the MT1 head plus the conventional intermetatarsal angle (IMA) and distal metatarsal articular angle (DMAA). RESULTS: The Wilson and Mitchell's osteotomies produced significant shortening (p < 0.001) in contrast to the three other osteotomies. All the osteotomies produced a reduction in the 3-D IMA. The Scarf and Stephens basal osteotomies reduced the DMAA. All of the osteotomies resulted in lateral translations and depression of the MT1 head. While there were no significant (p > 0.05) translational differences between the Scarf and Stephens basal osteotomies, there were rotational differences, with the Stephens basal producing significantly more plantar flexion (p = 0.000) and pronation (p < 0.001) than the Scarf. CONCLUSION: This geometric study indicated many of the MT1 head changes following metatarsal osteotomy to be out-of-plane translational and multiplanar rotations which cannot be determined using AP radiographs alone. CLINICAL RELEVANCE: We advocate judicious choice of osteotomy to achieve the desired correction of hallux valgus in each individual.

Assessment of the Sheffield Support Snood, an innovative cervical orthosis designed for people affected by neck muscle weakness.

BACKGROUND: This study aimed at quantifying the biomechanical features of the Sheffield Support Snood, a cervical orthosis specifically designed for patients with neck muscle weakness. The orthosis is designed to be adaptable to a patient's level of functional limitation using adjustable removable supports, which contribute support and restrict movement only in desired anatomical planes. METHODS: The snood was evaluated along with two commercially available orthoses, the Vista and Headmaster, in a series of flexion, extension, axial-rotation and lateral flexion movements. Characterization was performed with twelve healthy participants with and without the orthoses. Two inertial-magneto sensors, placed on the forehead and sternum, were used to quantify the neck's range of motion. FINDINGS: In its less supportive configuration, the snood was effective in limiting movements to the desired planes, preserving free movement in other planes. The Headmaster was only effective in limiting flexion. The range of motion achieved with the snood in its rigid configuration was equivalent (P>0.05, effect size<0.4) to that achieved with the Vista, both in trials performed reaching the maximum amplitude (range of motion reduction: 25%-34% vs 24%-47%) and at maximum speed (range of motion reduction: 24%-29% vs 25%-43%). INTERPRETATION: The Sheffield Support Snood is effectively adaptable to different tasks and, in its most supportive configuration, offers a support comparable to the Vista, but providing a less bulky structure. The chosen method is suitable for the assessment of range of motions while wearing neck orthoses and is easily translatable in a clinical context.

Standalone medical device software: The evolving regulatory framework.

The paper provides an introduction to the regulatory landscape affecting a particular category of medical technology, namely standalone software-sometimes referred to as 'software as a medical device'. To aid the reader's comprehension of an often complex area, six case studies are outlined and discussed before the paper continues to provide detail of how software with a medical purpose in its own right can potentially be classified as a medical device. The reader is provided an appreciation of how to go about classifying such software and references to support the developer new to the field in locating detailed regulatory support documents and contact points for advice.

Unmet needs: relevance to medical technology innovation?

This paper describes and discusses the role of unmet needs in the innovation of new medical technologies using the National Institute for Health Research Devices for Dignity (D4D) Healthcare Technology Co-operative as a case study. It defines an unmet need, providing a spectrum of classification and discusses the benefits and the challenges of identifying unmet need and its influence on the innovation process. The process by which D4D has captured and utilized unmet needs to drive technology innovation is discussed and examples given. It concludes by arguing that, despite the challenges, defining and reviewing unmet need is a fundamental factor in the success of medical technology innovation.

Passive haptics in a knee arthroscopy simulator: is it valid for core skills training?

Previous investigation of a cost-effective virtual reality arthroscopic training system, the Sheffield Knee Arthroscopy Training System (SKATS), indicated the desirability of including haptic feedback. A formal task analysis confirmed the importance of knee positioning as a core skill for trainees learning to navigate the knee arthroscopically. The system cost and existing limb interface, which permits knee positioning, would be compromised by the addition of commercial active haptic devices available currently. The validation results obtained when passive haptic feedback (resistance provided by physical structures) is provided indicate that SKATS has construct, predictive and face validity for navigation and triangulation training. When tested using SKATS, experienced surgeons (n = 11) performed significantly faster, located significantly more pathologies, and showed significantly shorter arthroscope path lengths than a less experienced surgeon cohort (n = 12). After SKATS training sessions, novices (n = 3) showed significant improvements in: task completion time, shorter arthroscope path lengths, shorter probe path lengths, and fewer arthroscope tip contacts. Main improvements occurred after the first two practice sessions, indicating rapid familiarization and a training effect. Feedback from questionnaires completed by orthopaedic surgeons indicates that the system has face validity for its remit of basic arthroscopic training.