From the Drawing Board to the OR, Part II
Read Part I of this case study to learn about Titan Medical and Ximedica's partnership for developing the SPORT Surgical System.
Design Begins with the User in Mind
Of paramount importance in medical device design is the user’s point of view. “Medical product development always has to start with the human needs and work from there into the engineering,” says Petrie. “The human component runs through Ximedica’s DNA due to our design-school origins. Our philosophy dovetails perfectly with the ‘FDA Waterfall Design Process’ [a development requirement for any medical device submission] that begins with user needs.”
So who exactly is the “user” of a robotic surgery system and what are their needs? The answers go far beyond the primary surgeon sitting at the workstation: The hospital purchasing agent is considered a user, as are the secondary surgeons at the bedside, scrub nurses working alongside the doctors, circulating nurses passing materials into the sterile field and, ultimately, the patient. Obviously, a thoroughly trained, core surgical team is fundamental. But the device itself needs to be designed from the inside out to function in a manner that not only optimally enhances the surgeon’s skills, but also benefits the hospital that buys it, fits smoothly into the OR space and workflow for a particular surgery, and provides the best possible outcome for the patient.
To collect the human data that would be the foundation of the SPORT Surgical System design map, Ximedica conducted rounds of in-person interviews with experienced hospital personnel—both those connected with Titan (like Dr. Fowler) and independent ones.
Ximedica also carried out a deep analysis of gallbladder surgery itself, again in consultation with experts.
Users were also asked to try out components of the system in mock-surgery settings. Together the user and surgical-procedure data informed the choices of the appropriate mix of features for the system, creating a concise product description to be designed to.
“We first defined the steps required to do an operation, then determined every little movement or action that needed to happen at each step,” says Dr. Fowler. “Finally, subcomponents of the device were designed to enable each action. Ximedica’s engineers were assigned to develop each subcomponent as needed. The most impressive thing about working with the Ximedica team has been their adherence to process, which was standardized, detailed and meticulous throughout.”
Aligning Functionality with User Needs
The next step was to evaluate the university prototype against the defined user needs and prepare a “gap analysis” of what was required to align function with those needs. “We used a systems engineering approach to break the challenge down into manageable pieces and assess the gaps between what the existing device could do versus what it had to do,” says Ximedica Senior Program Manager Corey Libby.
“There were three critical functional areas that needed to be de-risked from a technical aspect as well as a manufacturability aspect,” he says. “Through our design process, we developed a deep understanding of the user’s needs, making it very clear that successful implementation of the SPORT Surgical System must include highly advanced intra-cavity 3D imaging, instinctive control of the robotic components and extreme dexterity of the surgical instruments. As we progressed towards these milestones, everything had to be in compliance with FDA and EU medical device development requirements.”
Ximedica provided Titan with detailed documentation as each of the technical milestones (instrumentation, master controls and visualization) was achieved. “When one of our clients has a product undergoing development, good progress demonstrates value to investors,” says Libby.
“Titan needed to be able to show their investors where they were at any given moment and, more directly, that they had arrived at where they said they would be in a certain timeframe. Pulling it all together and figuring out how to do it quickly on a tight schedule was Ximedica’s side of the challenge.”
Engineering the Solutions – So How’d They Do That?
As the SPORT Surgical System project advanced from planning to prototype production, Ximedica’s 80,000 square feet of laboratory/engineering/product development space swung into action.
To tackle the instrumentation milestone, software engineers began by establishing a kinematic framework to mathematically describe the position and orientation of the two articulating instrument arms that emerge from the device once it enters the patient’s body through the single port. “Using MATLAB (Mathworks) enabled us to investigate different instrument designs and configurations very efficiently in the early stages of concept development,” says one Ximedica R&D engineer.
They then developed software systems (based on C++ OpenGL) to control simulated instruments, as well as the motor drives that move them, implementing the kinematics in a real-time environment. “We did a lot of development around the controllability, instinctiveness and suitability for intended tasks of the robotic instruments before we ever actually built one,” the R&D engineer says. “We controlled three-dimensional instruments on a computer screen first; it was an efficient tool which fed important information back into development.”
As the instrumentation design solidified, the group wrote additional computer code that would allow the master controllers (held by the surgeon) to manipulate the arms with all the intricate, fine-tuned movements required to perform a surgery. Initially conceived with five degrees of freedom (DOF) of movement, the arms were ultimately designed to have seven DOF based on projected clinical and commercial benefits that the SPORT Surgical System could provide surgeons in the future.
Computer Simulation Supports Product Development
“Computer simulation was pivotal in several important moments of discovery,” says the R&D engineer. “3D modeling demonstrated features that were very hard to visualize and understand without such tools.”
Adds a Ximedica design engineer, “The use of SolidWorks’ CAD platform (Dassault Systèmes) as a developmental tool allowed us to quickly visualize mechanical system interactions so we could virtually prototype concepts for validation.”
“Simulation saved us, and our client, time and money,” says a Ximedica software engineer. “We didn’t have to physically build each design and integrate it into a physical system. Surgeons testing the concepts were able to switch control between several simulated designs within a single study session, giving us a clear outlook as to the path we should take moving forward.”
An important side benefit of the extensive use of computer simulation was the realization that the in-house methodology created by Ximedica could be developed further into a training tool for the SPORT Surgical System. Dr. Fowler, who is also medical director of New York Presbyterian Hospital/Columbia University Medical Center’s Simulation Center, is enthusiastic about this discovery.
“In the process of looking at the animated CAD simulations created for the purpose of trialing different designs of the SPORT Surgical System, it became very clear that this would enable surgical practice as well, he says. “Simulation is an important tool for training and assessing surgeons’ skills.”
“We will encourage hospitals to require a certain level of performance in a simulator before allowing surgeons to work on patients,” he says. “This is, of course, not up to us: it’s a policy issue. The healthcare system needs to create the mandate and the metrics. But Titan will certainly partner with the hospitals and recommend guidelines for granting privileges in robotic surgery.”
The final technical milestone in the SPORT Surgical System project was the development of a sophisticated visualization system. Down-selecting from multiple potential architectures, testing both virtual and physical prototypes, the team arrived at a final custom “chip-on-tip” insertable camera concept. The high-definition, 3D camera folds into the entry device and then is deployed, once inside the body (along with the two instrument arms), to give the surgeon a direct view of the arms he or she is controlling. The surgeon sees the surgery through a 3D imaging portal at the master control station while manipulating the arms.
Additive Manufacturing Provides a Rapid Look at Designs
While computer-aided design tools saved time and money on prototyping, at many points during product development the engineers wanted to prove out their design ideas with real-world examples to assess the user-friendliness, and also the eventual manufacturability, of the surgical tools they were creating.
“One of the most challenging design areas was the connection point of a first set of wires to the distal end of the snake-like instrument arms,” says a Ximedica mechanical engineer. “Due to the size limitation imposed by minimally invasive surgery and the component materials required for this design, most conventional joint methods such as screws, welding and bonding were either not possible or their application was severely compromised. From similar-type product benchmarking we determined that additive manufacturing [AM] would be an effective material forming solution.”
The group produced many proposed solutions to various design challenges via AM using Ximedica’s Stratasys 3D printer. “We did a huge amount of AM prototyping for this project—three to five days per week for the entire fifteen-month period,” says the mechanical engineer. Their prototyping work will facilitate actual manufacturing once the SPORT Surgical System reaches the production stage, since a number of components will have already been designed for end-use manufacturing with AM.
Ensuring User Needs are Completely Met
With all subsystems developed, another round of user research established that the SPORT Surgical System was ready to move into lab- and then live-tissue testing. Successful deployment of the complete system was achieved in late 2013 and with regulatory strategy fully drafted, progress continued into 2014.
“Ximedica has provided Titan with a functional prototype that answers what every medical device executive wants to know: is this product actually going to work?” says Petrie.
The answer to date is a resounding yes, as demonstrated by live-tissue tests in December of 2013. Notes Titan CEO Hargrove, “Ximedica has been a tremendous partner for Titan. They have done a great job of managing our development and their accountability has been prevalent every step of the way. A good partnership can mean much more than just a good contract relationship—it can also mean support in managing the extraordinary changes in both vision and actions being demanded of all of us in this industry today.”