In response to indications of surgeon hand fatigue from marketing voice of the customer (VOC) data, BlackHägen Design was engaged to conduct a study of the ergonomic requirements and usage scenarios for an orthopedic procedure. The firm used ethnography and projective mapping methods to collect a significant amount of quantitative and qualitative data on the procedure.
First, a procedure map was developed to visualize the workflow, to understand steps that associated emotive metrics and workflow efficiencies, and to recognize opportunities for the user interface and, therefore, improve a surgeon’s procedural experience.
Two steps in the projective mapping exercises exhibited a noteworthy emotional connection. First, VOC data already indicated extensive time was taken to compare a navigation plan with actual patient anatomy; it became the source of much frustration. Secondly, there was a strong emotional connection during the actual bone resection. Surgeons beamed and said that it was the fun part of the procedure and enabled them to deliver better patient outcomes.
In the process of creating a procedure map, the researcher overlaid the ethnographic data from observing surgeons in the OR and cadaver lab with the interview data from the projective mapping exercises. They found evidence that supported the VOC complaints about an ergonomic issue with a surgeon’s grip during certain tasks within the resection step–their favorite step.
Within the resection step, an ergonomic analysis characterized different grip requirements depending on the user’s perception of gross versus fine manipulation of the cutting tool during the resection of bone. The original cutter’s form factor was based on a single grip option that was adequate for gross removal of bone, however, most of the users required moments of fine detail work to clean up the resection at the end of the step. Such fine, detailed manipulation tasks required a grip that uses the finger-hand-wrist muscle groups rather than the wrist-arm-shoulder muscles that were appropriate for gross resection. As a result, the new grip design needed to have an additional degree of freedom to accommodate a pencil grip—in addition to a pistol grip.
The specific form-factor geometry was determined through a participatory design study in the cadaver lab. A highly configurable study model of the cutter was designed, which allowed the researcher to custom fit the system to each surgeon who performed the procedure. It wasn’t a prototype and didn’t represent any singular design direction. The extensive adjustability would be cost prohibitive and hard to clean as a production solution. Instead, it was a measurement instrument that enabled the designers and end users to cocreate an ideal geometry for all the tasks in the resection step.
Once a pattern emerged among the participants for a common cutter-grip geometry, the industrial designers began to sculpt a grip shape that conformed to the pattern. The resulting cutter accommodated the biomechanical requirements of multiple grips depending on the user need and the task, without any unnecessary hand fatigue interfering with a critical step in the surgery.
Sean Hägen is the founding principal and director of research and synthesis at BlackHägen Design (Dunedin, FL).
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