A human factors engineering (HFE) process provides important safety benefits during orthopedic device design and development and may help smooth the regulatory process.

Pragadeesh Thirumurugan and Loren Kim, Kaleidoscope Innovation

Orthopedic surgical device manufacturers are increasingly taking advantage of HFE, but they may not know how to most effectively incorporate it into product development. Not engaging human factors specialists or doing so incorrectly has the potential to lead to setbacks in submissions to the FDA, delays in product launches, and more importantly, serious harm to patients.

While the mortality rate due to medical mistakes in orthopedic surgery is low, preventable human use-related errors could potentially contribute to serious or catastrophic post-operative complications. According to a 2015 article in the International Surgery Journal,
13% of orthopedic surgical errors were classified as errors in technique. These errors have the potential to be reduced by examining and understanding common use errors and “designing them out.” The goal would be a better user/device interaction, fewer errors and fewer complications and risk to patients.

Strong HFE capabilities and support can help manufacturers avoid these nine pitfalls when developing orthopedic surgical devices:

1. Minimal or no HFE considerations in early development

Waiting to incorporate HFE until the later stages of development, such as during the FDA-required validation study, might turn up use errors that could have been mitigated during the design and development process. The FDA might require changes in design, prolonging the device’s market launch. Usability testing done earlier in the design process opens a new dimension of product use and could reveal use errors with more time to make design improvements.

2. No anthropometric and ergonomic considerations

While surgeon input is important, it’s also important to consider other user groups such as circulating nurses, scrub nurses and technicians. Issues can arise when all relevant individuals’ hands, fingers, degrees of freedom of movement, gender and other anthropometric considerations are not studied.

Device designers should also consider users’ ergonomic preferences. The device should not only be intuitive but comfortable to all who need to use it. This should help mitigate issues that might lead to someone using a device incorrectly or choosing not to use it at all.

3. Insufficient pre-assessment and assessment of usability risk

Sometimes problems and complaints with predicate and/or similar devices are repeated in new designs. Use-related risk analyses can help manufacturers to predict potential errors and design to avoid these issues.

4. Failure to do formative evaluations

Not taking advantage of exploratory formative evaluations could lead to discovering errors or design flaws when it is too late in the process. Performing formative evaluations can reveal ways to improve the design to help ensure the product is safe and effective to use.

5. Unrealistic training for usability testing

During validation testing, training must reflect the real-world scenario, as it may affect the participant’s performance.

6. Ignoring supporting materials and processes

Packaging and product labeling are as important to assess as the product itself. Some examples of this include misread or complicated instructions for use, crowded text that may deter a user from thoroughly reviewing product support and instructions for transporting, cleaning and/or discarding the product.

7. Designs based on stakeholders rather than end users

Instead of designing for the actual users, companies may defer to stakeholders such as the orthopedic sales rep, marketer or orthopedic engineer. Further, while orthopedic surgeons can be involved in a product’s invention, it is important to obtain wider surgeon input rather than default to an orthopedic surgeon-inventor’s individual preferences.

8. Disregard for surrounding tissues/muscles

Sometimes overlying structures like soft tissues and muscles on the body around the bones are overlooked while testing on plastic models. It is critical to consider the actual complications or serious consequences that could occur in real surgery.

Cutting tools similar in appearance but different in performance

Understanding the differences between cutting tools is imperative. Designing to differentiate cutting tools that look similar but do not perform alike is a critical HF input.

Ultimately, a solid HFE team focused on making orthopedic products more intuitive may contribute to improved patient care. For example, the intended users might be able to perform their tasks with less distraction from device design-related challenges. Implementing HFE principles early may help to inform the design of safer and more effective devices.

Pragadeesh Thirumurugan is a human factors engineer and specialist in anthropometric and ergonomic evaluations at product design and development firm Kaleidoscope Innovation. He earned his M.S. in industrial engineering, human factors from Penn State University. Loren Kim is senior human factors engineer at Kaleidoscope with previous engineering experience at Baxter and Emergo by UL. She has applied HFE principles to medical device development, including combination products for rare conditions and complex systems.

The opinions expressed in this blog post are the author’s only and do not necessarily reflect those of Medical Design and Outsourcing or its employees.