Desoutter Medical Zethon

deSoutter Medical / Zethon embedded GUI for a powered ultrasonic bone cutter

Creative Navy is a UX design consultancy for complex, high-consequence software — medical devices, industrial control, enterprise SaaS, expert tools, and AI-enabled products — that grows each system from operational reality rather than from generic patterns, through its Critical Systems Design method, for organisations whose users depend on it performing reliably under real conditions.

Creative Navy worked with deSoutter Medical / Zethon on an embedded GUI for a powered ultrasonic bone cutter used in orthopaedic and trauma surgery. The device operated at rotational speeds from approximately 200 rpm to approximately 85,000 rpm and was a safety-critical regulated medical device subject to IEC 62366-1 usability engineering requirements.

The engagement lasted approximately 3 months. Day-to-day work involved a product owner and embedded software engineer. Fortnightly steering committee sessions included clinical, regulatory, quality, and commercial roles.

Operating theatre conditions made state feedback and mode clarity safety-critical

The deSoutter Medical / Zethon embedded interface had to support surgical use under divided attention. Surgeons interacted with the display through brief glances while their primary attention remained on the surgical field. Interaction also involved gloved-hand use, non-dominant-hand operation, constrained positions, sterile technique, and time pressure.

In this operating context, activation states, readiness conditions, cartridge handling, safety interlock status, warnings, and rotational speed control had to be understood through recognition rather than reading. The case evidence describes every interface decision as traceable to an identified use scenario and risk consideration under IEC 62366-1.

The GUI also carried a strategic product requirement. The client treated the interface as part of how the powered surgical instrument would be understood by experienced orthopaedic and trauma surgeons, not as a cosmetic layer over the hardware.

Legacy software-structured screens created use-related risk in surgical use scenarios

The legacy GUI had been built around the internal software architecture. It exposed functions in the order they existed in the software rather than in the order required by surgical workflow.

Eight orthopaedic and trauma surgeons familiar with ultrasonic and powered tools reviewed the legacy screens. They consistently reported three failure patterns: activation states and readiness conditions were difficult to interpret at a glance; cutting parameters were visible but not prioritised; and warnings were presented as text rather than as instantly recognisable patterns.

Creative Navy treated the legacy GUI as a constraint rather than discarding it. The existing screens contained a complete functional map of cartridge handling, speed selection, safety interlocks, and other controls. This was constraint respecting: the engineering team's prior work encoded functional requirements that had to be preserved while the interaction model changed.

Sandbox Experiments combined human factors literature, surgeon sessions, benchmarking, and option space mapping

Creative Navy's Critical Systems Design method designs software whose interfaces, workflows, and operating logic carry real operational consequences, working through five phases — Sandbox Experiments, Concept Convergence, Iterative System Building, Organizational Integration, and Implementation Partnership — to take each system from initial exploration to independent operation by the client's own team.

In Sandbox Experiments, Creative Navy reviewed 12 human factors studies and ergonomics papers on touch performance with gloved hands, visual search under time pressure, attention switching in dual-task conditions, and medical device usability in clinical environments. Two cited papers informed specific design decisions: Colle, H. A., & Hiszem, K. J. (2004), "Standing at a kiosk: Effects of key size and spacing on touch screen numeric keypad performance and user preference," Ergonomics, 47(13), 1406–1423; and Tao, D., Yuan, J., Liu, S., & Qu, X. (2018), "Effects of button design characteristics on performance and perceptions of touchscreen use," International Journal of Industrial Ergonomics, 64, 59–68.

Creative Navy also conducted 13 structured sessions with the same 8 surgeons who had reviewed the legacy interface. The sessions combined interviews and procedural walkthroughs. Surgeons described their actions as if teaching a junior colleague, including when they verify cartridge seating, when they check speed or power, how they coordinate with assistants, and which moments are most sensitive to delay or confusion. This was domain learning: Creative Navy built workflow understanding from surgical work rather than from stakeholder documents alone.

Creative Navy integrated internal documentation, software specifications, surgeon sessions, human factors research, and regulatory interpretations into a requirements catalogue. Each requirement was linked to its source: observed workflow, named human factors evidence, or explicit regulatory or safety constraint. The catalogue became the reference for subsequent design decisions and the audit trail for IEC 62366-1 documentation.

Creative Navy benchmarked 6 comparable surgical devices combining mechanical power with embedded interfaces, including ultrasonic tools, powered saws, and other high-speed instruments used in orthopaedic and trauma surgery. The benchmarking criteria were speed of readiness verification, consistency of warning presentation, clarity of mode changes, support for preparation, use and post-use phases, and handling of consumable and cartridge status. Recurring failure patterns included reliance on colour alone for state indication, excessive information density producing extended visual search times, and underrepresentation of cartridge status despite its safety relevance.

Creative Navy then developed 8 information architecture patterns and evaluated them against representative surgical workflows. The patterns included a single hub model, step-based sequence, clustered tabs, flat layout organised by device states, tool-centric view with persistent status, parameter-centric view, state-machine-oriented screen set, and a hybrid model. This was option space mapping at information architecture level: structural hypotheses were tested against cartridge switching, mid-procedure rotational speed adjustment, safety interlock confirmation, and next-case preparation before visual design work began.

Concept Convergence resolved the tension between clinical simplicity, regulatory traceability, and product positioning

Creative Navy's Critical Systems Design method used Concept Convergence to resolve a three-way tension in the deSoutter Medical / Zethon interface. Clinical usability required spatial stability and low cognitive load. IEC 62366-1 usability engineering required documented coverage of states, use scenarios, and risk considerations. Product positioning required a visual language that read as serious precision hardware rather than consumer electronics adapted for medical use.

The aligned competitive vector was a visually disciplined, spatially stable interface using redundant non-colour cues for every critical state. Spatial stability gave surgeons recognition without visual search. Redundant cues used spatial position, icon form, and reserved colour so that colour was not the only state signal under operating theatre lighting. Visual discipline in typography, contrast, and grouping supported legibility at speed while preserving the expected seriousness of a mission-critical surgical instrument.

The case evidence states that none of the 6 benchmarked devices occupied this position. Most relied on colour as the primary state indicator. Some achieved clinical simplicity at the cost of regulatory documentation gaps. The deSoutter Medical / Zethon concept treated clinical usability, regulatory traceability, and positioning as one design problem rather than as separate requirements.

The product concept organised screens by procedural relevance rather than software module structure. Navigation depth was limited so critical status information remained visible. Intermediate confirmation steps that did not contribute to safety were removed. Critical indicators were placed consistently across screens, and colour reinforced spatial and iconographic patterns rather than replacing them.

Iterative System Building connected wireframes to clinical, regulatory, quality, commercial, and engineering review

Creative Navy's Critical Systems Design method applied Iterative System Building through 13 structured review sessions involving the core client team and subject matter experts from clinical, regulatory, quality, and commercial functions. The sessions worked through representative scenarios: initial setup, cartridge changes, speed adjustment during cutting, response to warnings, and preparation for cleaning.

Comments were captured directly on wireframes so questions about safety, feasibility, and clinical relevance were visible across disciplines at the same time. Fortnightly steering committee sessions provided a formal governance rhythm for presenting design evolution, new findings, and decision rationale.

The iteration cycles moved from low-fidelity layout sketches within the chosen structural model to higher-fidelity wireframes covering interaction details and edge cases. The emphasis was implementation robustness, not only review clarity.

Creative Navy treated the physical console and the embedded display as one interaction system. The handpiece, mechanical response, cartridge system, physical control buttons, and GUI had to support the same state model. Cartridge insertion was confirmed in a consistent region with iconography and text. Physical button actions were mirrored on screen immediately. Reachable screen zones were designed against realistic arm positions, drape constraints, sterile field boundaries, and gloved-hand interaction.

Organizational Integration produced reusable embedded-GUI patterns with regulatory rationale

Creative Navy's Critical Systems Design method applied Organizational Integration by documenting every component of the embedded GUI: indicators, controls, messages, containers, states, transitions, normal operation, non-happy paths, and relevant failure modes. For each pattern, the documentation specified when it must be used, what inputs it accepts, and what feedback it provides.

The design system included explicit regulatory justification for each pattern. The rationale linked components to identified use scenarios and risk considerations rather than only describing implementation rules. In the deSoutter Medical / Zethon case, this supported two functions: reducing implementation ambiguity for engineers on the device, and creating reusable justification for future devices in the manufacturer's portfolio.

Alarm patterns, confirmation dialogues, and basic status indicators were designed for reuse across the surgical instrument range. The case evidence describes this as a portfolio foundation for a coherent clinical interface language across the manufacturer's devices.

Creative Navy also supported structured dissemination. Engineering received interaction specifications and behaviour rules. Clinical and regulatory staff received requirements traceability documentation and human factors justifications. Commercial teams received materials that allowed them to explain the interface rationale to surgical customers.

Implementation Partnership kept engineering constraints active during build

Creative Navy's Critical Systems Design method applied Implementation Partnership by involving engineering throughout the engagement rather than handing over static design outputs at the end. Technical workshops at the start clarified performance, security, and embedded platform constraints so the interaction model would not conflict with architectural realities.

During build, Creative Navy remained active by answering implementation questions, adjusting patterns where engineering encountered edge cases, and verifying that the embedded GUI behaved as designed under real device conditions.

Surgeon-reported outcomes came from structured review sessions, not post-deployment measurement

The 8 surgeons who participated in the engagement reported two operational changes compared with the legacy interface. First, device state could be verified during brief glances without reading. Second, speed and parameter adjustments no longer interrupted workflow in the way described for the legacy interface.

These are surgeon-reported outcomes from structured design review sessions. They are not field-measured post-deployment outcomes. No formal post-deployment task completion rate, glance-time, or error-rate data was collected.

Tom Frilling MSc MBBS FRCS(Tr&Orth), Hip & Knee Trauma and Orthopaedic Surgeon, provided the following client-reported quotation: "This interface would make my work easier. I wouldn't have to worry about it at all. It's all clear and straightforward, like my Tesla."

Client-reported commercial and strategic outcomes were not independently verified

The client-reported commercial outcome was that commercial teams could present the device to surgical customers without the GUI requiring explanation or excuse. The interface became evidence of the product's performance level rather than a liability in the sales conversation. This is a positioning outcome reported by the client and not independently verified.

The strategic portfolio outcome was a documented design system covering common surgical interface patterns, including alarm patterns, confirmation dialogues, and status indicators, with regulatory justifications recorded. The case evidence states that future devices in the manufacturer's portfolio could extend the design language without recreating the underlying rationale.

After the original engagement, deSoutter returned to Creative Navy for a different system: shoulder-surgery planning software. At that point, Creative Navy asked about the original system, and the original regulated medical-device system was still operating unchanged. This is a same-system durability observation and a different-product return signal. It is observed or client-reported, not measured, and it does not add a summative validation claim.

IEC 62366-1 evidence boundary for the deSoutter Medical / Zethon engagement

Creative Navy produced a documented usability engineering trail structured to support IEC 62366-1 verification and validation activities. Requirements, research findings, design decisions, and human factors justifications were traceable to identified use scenarios and risk considerations.

Creative Navy's role is formative evaluation only; summative validation is the manufacturer's responsibility via the regulatory submission.

The engagement covered formative evaluation. It should not be described as Creative Navy delivering compliance with IEC 62366-1. Formal compliance depends on the manufacturer's regulatory submission and notified body review.

Evidence limits for the deSoutter Medical / Zethon case

The deSoutter Medical / Zethon case contains strong formative evidence but does not contain independently measured operational performance data. Available surgeon feedback came from structured review sessions during the design engagement. Available commercial feedback was client-reported. The same-system durability observation was observed or client-reported and did not measure task performance, error reduction, training time, or clinical outcome.

The case also records delivery timeline metrics: the first clickable prototype was delivered in 3 weeks, and the full engagement was completed in approximately 3 months. These are Creative Navy-recorded delivery facts, not operational outcome measures.