Photo by Mark Wilson
The problem with knee replacements, says John Slamin, MDE ’74, is that they are just that—replacements.
“An off-the-shelf knee is a very loose interpretation of what a knee is,” says Slamin, holding a model of a standard substitute at the Burlington, Mass., offices of ConforMIS, where he is vice president of engineering. “It is highly symmetrical, whereas your actual knee structure is not.”
The result? Slamin says patients report that it feels different. And because it is not an exact match, it leaves bone exposed—which allows for potential bleeding—and forces people to adjust their gait.
“They just don’t fit right,” he says, making for a sizing shortcoming that affects the more than half a million people annually who undergo knee replacement surgery in the United States.
Enter Slamin and ConforMIS with a custom replacement knee implant, which offers an exact replica of the affected knee. The process begins with a CT scan of a patient’s knee, which is then recreated using special design software, fabricated, and sent to the patient’s doctor in a package not much bigger than a shoe box.
“It is the perfect blend of mechanical engineering and medicine,” says Slamin, one of seven Wentworth grads at ConforMIS.
Slamin can be confident that this new knee is the best thing on the market because he also developed the next-best thing. A 33-year veteran of the research and development department at Johnson & Johnson, Slamin has been engineering knee replacements for the majority of his career, joining ConforMIS in 2007. The custom knee has been his greatest challenge as an engineer.
“We are designing a product for infinite variability,” says Slamin. “I don’t know of any other product where that is true.”
—Dan Morrell
