Q&A with Marc Horner


The technical lead for health care at ANSYS reflects on current and future applications for modeling and simulation, from hip replacements to aneurysms.

Marc Horner is a member of MDIC’s Modeling & Simulation Steering Committee. He earned his Ph.D. in Chemical Engineering from Northwestern University in 2001. Marc started out at ANSYS by providing support for biomedical clients, mostly in the areas of cardiovascular devices, orthopedics, microfluidics, drug delivery, and packaging.  He has developed numerous modeling approaches that can be used to establish the safety and efficacy of medical devices. He now helps coordinate business and technology development for the health care industry.


The ANSYS Model Patient demonstrates a selection of patient-specific computational modeling examples.  Shown here are drug delivery to the eye and nose, cardiovascular flow in the aorta, and the flow of cerebrospinal fluid in the brain.  This is but a small selection of the computational modeling examples that utilize patient anatomy to inform device development.  Acknowledgements: Brain and nasal geometries courtesy Materialise and aortic geometry courtesy Simpleware.

The ANSYS Model Patient demonstrates a selection of patient-specific computational modeling examples. Shown here are drug delivery to the eye and nose, cardiovascular flow in the aorta, and the flow of cerebrospinal fluid in the brain. This is but a small selection of the computational modeling examples that use patient anatomy to inform device development. Acknowledgments: Brain and nasal geometries courtesy Materialise; aortic geometry courtesy Simpleware.

MDIC:  What does ANSYS do?

Marc:  ANSYS develops simulation software that solves equations that describe fluid flow, electromagnetic fields, or mechanical deformations. For example, you might use our software to optimize the shape of an airplane wing to minimize drag and maximize lift or optimize your cell phone antenna for optimal power usage with minimal heating.  ANSYS tools are heavily used in the aerospace, oil and gas, automotive, and electronics industries.  Health care is an emerging market for simulation.

MDIC: What are the benefits of using modeling & simulation for product development?

Marc: Modeling & simulation (M&S) tools help reduce the time and cost of bringing new products to market by allowing companies to perform virtual testing very early in product development.  In this way, simulation tools can help identify poor candidate designs before building a single prototype.  This is very different from the design-build-test paradigm of the past, where physical prototypes were required to identify good ideas and filter out the bad ones.  We see time and again that the initial feasibility timeline is shortened when companies use M&S and that the success rate of the product development process is increased when simulation is used early and often.

MDIC: What kinds of projects does ANSYS work on in health care?

Marc: We are involved in most aspects of medical device development, from wireless power transfer to orthopedic implant wear testing to flexible tissue valves.  One great example of the use of M&S in the medical device industry is the stent.  A stent is a small wire mesh or slotted tube that acts as a structural support in an unhealthy region of a blood vessel.  The stent expands and contracts with the vessel wall during each heartbeat.  And after many millions of cycles, a stent may break at one or more points because it is not strong enough to stand up to constant cycling.  Modeling has been used extensively to help identify where these types of failures might occur.

MDIC: What’s one amazing example you’ve seen of modeling in the medical device industry?

Marc: ANSYS recently completed a project with a company called Simpleware. They develop software that can be used to extract anatomical structures from medical images, such as a 3D model of a bone taken from an MRI.  The question we asked was, could we use the medical scan data to identify the optimal position of a hip implant for a given patient?  In a situation like this, micromotions—the very small relative motions that occur between the implant and the bone—are very important.  If there’s too much micromotion, the implant won’t bind to the bone.  So we set up a study with a thousand potential implant positions, and then studied how the implant would perform in each case.  Significant validation is required before we can start providing surgical guidance, so in the short term we see this workflow as a way for orthopedic companies to perform virtual clinical trials of implant performance.

MDIC: Looking out 20 years, how much potential does modeling and simulation have to change patients’ lives?

Marc: The continued integration of M&S into the product development process will greatly improve medical device safety and performance over the next 20 years.  But there is also potential for M&S tools to assist with clinical decision-making and surgical planning.  For example, a cerebral aneurysm—which is a bulge in a blood vessel in the brain—is a naturally occurring condition that may or may not pose an immediate risk to the patient.  It is currently left to the surgeon to determine if a procedure to stabilize the aneurysm is warranted.  ANSYS is currently involved in a project that aims to provide an assessment of aneurysm stability.  This is accomplished through a patient-specific model of blood flow and vessel wall deformation, which is tuned using high-resolution imaging.

MDIC: What are the biggest barriers to using M&S in the medical device industry?

Marc: One of the key challenges is our lack of understanding of the material properties of biological fluids and tissues.  This information is critical if we want to be able to predict the interaction between a device or surgical tool and the surrounding tissue, as in the case of a bone screw or a lens implanted in an eye.  And we typically don’t offer treatments to healthy individuals, so the most valuable information would come from diseased tissue.  The fact that material properties continually evolve during the progression of the disease makes this an even more challenging problem.

While there are efforts currently underway, it’s going to be a long time before we have a comprehensive repository of material property data that’s representative of healthy humans and those with various diseases.

MDIC: How can MDIC contribute to the conversation?

Marc: MDIC is already challenging its membership to address critical medical device industry problems, such as how to use M&S to predict the potential damage of a medical device on red blood cells.  MDIC is also trying to establish the value of M&S for device development.  It is very exciting to see competitive companies coming together to work on these problems.  The shared scientific value has always been there for these companies.  What has changed is that MDIC provides a neutral environment where scientific information can be shared without infringing on intellectual property.