Designing a Streamlined Hip Replacement System
Responsive Orthopedics
Role:
Design Engineer
Timeline:
2 years
Skills:
User Research, Competitive Analysis, Usability Testing
Context
I was a design engineer at Cor Medical Ventures, a medical device development company that partners with clients to bring their ideas to market. My role was to execute and bring these projects, specifically the Responsive Orthopedics Hip Replacement Set, to fruition.
Our client reached out with a proposal for a cost-competitive, efficient hip replacement set. They had also already identified a team of surgeons who we would be consulting with on this endeavor.
Problem
Hip replacement sets do not currently provide surgeons with the most optimal tools to do their job and are often too expensive.
The current front-runners for hip replacement systems market their sets as premium high-end products, with all the bells and whistles (many of which surgeons end up not using). They focus on providing surgeons with as many options as possible but with a heavy price tag that affects the overall cost of the operation.
Goal
Create a streamlined hip replacement set that includes only the essentials required for a successful hip surgery, at a more affordable price point. This set must incorporate the following features:
Dual implant geometry compatibility
Instrumentation set is compatible with both hip stem geometries offered (ML and Dual)
Accommodation for two surgical approaches
Instrumentation and implants are compatible with the standard and direct anterior hip surgery approaches (the two most common hip replacement techniques used.) ​
A cost-reduced hip implant system to directly compete with premium priced alternatives
Target Users
Orthopedic Surgeons, including those who operate using either the standard or direct anterior approach
About surgical approaches:
The standard and direct anterior approach refer to the two most common locations on the hip that the surgeon incises to access the hip joint.
The standard approach is the most widely used, while the direct anterior is a newer method that results in faster recovery times.
While there are a handful of other approaches sometimes used in hip surgery, these are the two most widely adopted and performed by our surgeon team.
User Research
User research and feedback were an integral part of the development of this project in order to assure that the final product would best address the requirements of orthopedic surgeons. Throughout the project, I had frequent direct communication with our surgeon team in order to gain their input on the current competitive landscape. I also had the opportunity to observe them perform hip surgeries. During these cases, not only would the surgeon talk me through their procedure, but other members of the operating room would provide their input as well. Nurses, scrub technicians, and even competitor representatives were eager to share their insights on the current competitors in the market. This helped me gain an even more holistic view of my user group and of the problems we were trying to address.
Current Constraints
Current instrumentation sets only cater to one style of implant
There are two common geometries for hip implants (ML and Dual) which currently require different instrumentation sets. If the surgeon decides to change which style of implant to use in the middle of a surgery, it can be taxing to locate and introduce the new set into the operating room.
Current instruments have various usability issues
There are various usability issues associated with individual instruments across the commonly used competitor hip replacement sets, including instrument length and grip comfort.
The Direct Anterior approach is not accommodated in most standard instrumentation sets
The direct anterior requires specialized equipment that is not available in most standard hip replacement sets and instead requires a new special kit.
Product Requirements
Based on our findings and observations of surgeons actively performing cases, we arrived at the following high priority requirements for our product.
Prototyping
Once we defined our project requirements, I created 3D models of our instrumentation set with support from our lead mechanical engineer.
We chose not to reinvent the wheel in the areas where current instruments performed well and focused instead where there was inefficiency in the surgery process. One innovation included combining two separate instruments into one which could be configured into different modes at the push of a button, depending on the surgeon’s need.
Usability Testing
We held 3 cadaver labs total with various members of our surgeon team, with a round of iteration in between each lab. During these studies we observed as the surgeons used our instrument and implant prototypes through a mock hip replacement and discovered new areas for improvement in instrument functionality and ergonomics.
Testing Takeaways
What users say versus what they mean
Although frequent and direct communication with our surgeon user group informed and guided our design decisions, the surgeons would still have additional feedback when they saw and tested parts in person. Being able to tease apart the surgeon said versus their interactions with the instruments was critical in order to truly design what they were looking for.
Communicating clear product requirements
After one round of testing, one piece of feedback we recieved was that three instruments needed to be longer. When asked what the ideal length would be, the suggestion was “forearm length”. One of our interns who handled the design update happened to be much taller than average. As a resultt, our instruments were too long because his forearm length was also much longer! Luckily we caught this during this second round of usability testing and dialed the length down correctly afterward.
Final Design
Our final hip replacement set included the following features:
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Dual compatibility for both ML and Dual Hip stem geometries
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A cost-reduced hip implant system to directly compete with premium priced alternatives
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Accommodation for both standard and direct anterior approaches
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Reduction in the number of instruments in the total kit from the industry standard by 36%
Project Takeaways
User feedback is invaluable
Having an “on-demand” team of surgeons who we could regularly consult with was immensely helpful in guaranteeing that we were successfully designing for our end user. I also found during my observations of live surgeries that the other members of the operating room (nurses, technicians, and even competitors’ sales reps) were more than happy to chat with me about their perspectives on the hip replacement sets they used. This lent an interesting additional perspective, since they noticed details that the surgeons may not have brought up or realized.
Designing for accessibility
If I were able to revisit this project, I would have liked to also include female and newer inexperienced surgeons into our initial research or during usability testing. Because our surgeon team consisted of experienced, white male surgeons, our instruments were designed to accommodate their larger hands. It would be interesting to see if the instruments were still comfortable to use for surgeons with smaller hands, as well as to see if inexperienced surgeons would find the instruments intuitive and easy to use.
Similarities across physical and digital design
Looking back on this project, I find many similarities in the design process between physical and digital product development. No matter what you're making, it is not only critical to have well defined product requirements, but to also remain adaptable to new developments throughout the project. Additionally, receiving feedback from experts and testing with your target audience better guarantees that you are making something that your users will actually need and will enjoy using.
Outcome
Our client successfully sold the hip replacement set shortly before FDA submission to a larger medical device company looking to add orthopedic devices to their portfolio. Two years after the initial submission, we were granted FDA approval, having met all requirements to be safe for use!
