For all that’s said about the heart, your head is where you really live. Not only does it hold your brain, the seat of consciousness and choice, but it also contains four of the five big senses you use to perceive the world: sight, hearing, taste and smell. And on top of that, we humans rely enormously on our faces to communicate, identify and relate to each other. So damage to the head, whether caused by trauma, cancer, or congenital defect, is definitely a big deal.
FACE FORWARD: Heather Logan is on the cutting edge of prosthetic design, creating a new field in medical modelling.
Photos by Kelly Redinger
The Institute for Reconstructive Sciences in Medicine (iRSM), based at the Misericordia Hospital in Edmonton, was founded by Dr. Johan Wolfaardt and Dr. Gordon Wilkes in 1993 to focus on research and treatment of skull and facial problems. At that time the institute was known as COMPRU, for Craniofacial, Osseointegration, and Maxillofacial Prosthetic Rehabilitation Unit, and its international reputation has grown rapidly. Drawing on the expertise of surgeons and engineers, and an artist, the institute is a world leader in patient care and innovation. As well, the iRSM collaborates and shares its knowledge with other prestigious institutions around the world, to improve treatments for patients with serious skull and facial problems.
Skull surgery is nothing new; archaeologists have found skulls from as early as 6500 BC showing signs of trepanning, a practice of boring holes into the cranium. Patients often survived, evidenced by the fact that the unearthed skulls showed signs of healing.
Although the techniques and equipment have improved dramatically over the millennia, it wasn’t until the invention of the X-ray that surgeons have been able to get an idea of what to expect once they got inside. Even then, much of the information surgeons needed to formulate a plan wasn’t available until they had opened the patient’s skull. That’s one of the reasons surgery can take so long.
So planning is everything, and the more data surgeons have to work with, the better the preparation, and the sooner the patient can be sent to the recovery room. At iRSM, the team uses modern advanced imaging technology, along with sophisticated computer modelling techniques and 3-D printing, to prepare extremely detailed surgical plans long before the patient hits the operating room.
Heather Logan is a surgical design simulationist at iRSM. Before earning her M.Sc. in rehabilitative medicine, she took a degree in industrial design. She helps to provide the planning to ensure that a surgery is carried out as efficiently as possible. One of the more challenging projects in which she’s recently been involved was helping to plan for a complex surgery to reconstruct a patient’s nose. Calling on her design skills, she worked from three-dimensional scans of the patient’s face to create a plastic template for the surgeon to use in shaping a section of bone removed from the patient’s rib to form the new nose. Jawbone reconstruction, in contrast, often uses a section from the patient’s fibula, the smaller bone that runs alongside the shin bone.
Traditionally in this sort of reconstructive surgery, the surgeon would need to work freehand, relying only on experience and judgment to shape the bone. This takes time, and since bone is living tissue, it can’t be kept outside of the body for very long. Preparing a precise template in advance, using 3-D modelling on a computer, can improve the precision of the finished piece and reduce the time a patient spends in surgery.
“One of the biggest things that we’ve been working on lately,” Logan says, “is the difference that surgical planning makes on the outcome for the patient.” While some medical modelling has been applied for the past 12 years, it’s only in the past couple of years that medical teams have been able to do so much of the design and preparation ahead of time without intrusively involving the patient. Since the kind of work that Logan does is so new, there hasn’t been enough hard data to give solid numbers on just how much difference it makes, but the team is recording its successes.
Logan grew up seeing the challenges her brother, who has a disability, faced daily. “I really always wanted to work with people who have a disability,” she says. “I worked as a personal support worker for five years. And I studied industrial design to learn how to make tools that could make life a little easier for people.”
In addition to her work in surgical planning, Logan draws on her design background to craft prostheses for ears, noses and eyes, usually moulding them out of silicone. While about 90 per cent of her medical modelling and surgical planning is for cancer patients, Logan estimates that her work on facial prostheses is about evenly split between cancer patients, congenital defects, and trauma. Pre-injury 3-D scans are not often available for accident victims, so she must often work from photographs taken of the patient before the accident.
One of the more surprising challenges is deceptively simple: getting the colour right. If someone’s going to be wearing an artificial ear, it ought to match their natural colour, after all. Lindsay McHutchion of the institute is responsible for colour-matching and materials testing. The institute recently acquired a spectrophotometer, which measures colour electronically, but it still has limitations, in part because one’s own natural colour changes from day to day and hour to hour. Measure the colour of your ears just after you come in from a brisk walk in a chilly breeze, and they will be unusually red.
Another project at the Institute is the osseointegrated implantation, where an implant is actually anchored directly to the bone. This is useful for securing facial and dental prosthetics to help a patient eat, speak and swallow.
Particularly interesting, though, is its use with bone-conduction hearing aids. Traditional hearing aids function as loudspeakers worn in the outer ear, transmitting amplified sound waves through the air within the auditory canal to the eardrum. In a bone-conduction device, the sound vibrations move through the solid bone of the skull itself. There are bone-conduction headsets on the market, which are worn externally and simply rely on pressure with the skull to transmit the vibrations, but osseointegrated implants go well beyond that; as the name suggests, they are integrated directly into the bone. An external microphone is still used to pick up the sounds to begin with, but the signal is then sent to the implant.
The work at the iRSM is novel and groundbreaking. It is also on the cutting edge in that more often patients are living past cancer and in need of reconstruction. And it puts the art in science.
Much of the work at the iRSM is supported by the Dr. Murray E. Mickleborough Research Chair in Interfacial Biomechanics.
In 2009, Mickleborough, himself a maxillofacial surgeon, was diagnosed with throat cancer, and became a patient at iRSM. He was impressed with the work the institute carried out, and made a gift of $1 million to support continued research. That, combined with money from Alberta Cancer Foundation and the Caritas Hospitals Foundation, has led to the creation of the new research position at the institute, named in honour of the doctor, who died in 2011.