I had been thinking for a while about writing a blog on medical care and how engineering simulation (or CAE) can really help patients and surgeons. With the Supreme Court’s recent verdict on healthcare, it reminded me to do my part!
Over the years, I’ve seen numerous presentations by my colleagues and others about the use of simulation to design blood pumps and other devices, for research in drug delivery using inhalers, or even in the human eye, all simulating physiological phenomena. What recently captured my attention was a presentation by our resident biomedical expert, Marc Horner, at the ANSYS Confidence by Design workshop in Minneapolis on May 8th. Marc showed how these tools can help compute the risk of bone fracture in individual patients and how an orthopedic surgeon can narrow down choices for hip replacement.
In the spirit of full disclosure, I have had this surgery twice on the same hip. The first hip implant lasted for about 8 to 9 years. But it clicked when I moved my leg, and as much as I believed that it was not the right fit, it is not as easy to change it out as you do with parts in your car.
Simply put, the hip is a ball and socket joint. When damaged, due either to injury or arthritis, the hip joint has to be surgically replaced by an artificial joint. You may appreciate the fact that our natural joints are as different as our DNA. The surgeon tends to find the best fit to suit the patient. This is where CAE tools can really help surgeons and implant makers.
In 2000, this is how my surgeon explained it to me. He took X-rays and CT scans of my diseased hip joint and, based on the results, he selected a set of different sizes of prosthetic ball joints (titanium hip prosthesis with a ceramic or metal head and polyethylene or ceramic or metal cup). During surgery, he tried the different sizes and finally settled on the one he thought made the best fit. In my case, it seemed he might have been a bit off, which resulted in the clicking sound. Over the years, the wear led to erosion of the cup surface. The resulting debris caused a fracture of the trochanter part of my femur.
What if these implants could be customized to the needs of each patient? That might be asking too much. Marc’s conference presentation discussed an ongoing study (VPHOP: Human Femur Population Indexation) whose goal is to develop a multiscale model of bone strength that can be used to predict the risk of bone fracture on a patient-by-patient basis. Marc illustrated how this same technology could be used to optimize implant designs to better fit patient populations and subpopulations. If successful, this process would take some trial and error out of the operating room.
The presentation included a study on wear on the hip joint after repetitive motion, conducted by combining ANSYS software with technologies from our partners, Materialise and AnyBody Technologies. I won’t bore you with all the details of how this done; the information is in the published references.
Similar patient-specific treatments are being carried out in many areas beyond orthopedics, including aneurysm, stroke, and targeted-radiation dosage. Even the FDA now formally recognizes simulation as a tool that can benefit the product development and approval process.
So next time when I go to doctor’s office, I will make sure that he knows what I know about the use of simulation in deciding my treatment.