Sandra She­fel­bine has always been inter­ested in the human body as a mechan­ical system: “The lungs are gas exchangers and the heart is a pump,” said the asso­ciate pro­fessor of engi­neering.

As an under­grad­uate simul­ta­ne­ously studying heat transfer and evo­lu­tionary biology, she real­ized that the system of par­allel arteries and veins in arctic birds’ legs, which keeps them warm enough to stand on ice, is just an example of counter-​​flow heat exchange. “I really enjoy seeing the body in terms of mechan­ical per­spec­tives,” she said.

As a grad­uate stu­dent, this interest became her life’s work. She­fel­bine now studies the mechanics of bone—both the unique mechan­ical prop­er­ties and the active response of bones to load. The system presents sim­ilar ques­tions faced by engi­neers who study mechanics across length scales, she said. “The equa­tions are still the same, the mechanics are still the same, the graphs are still the same.”

She­fel­bine joined the fac­ulty in the Depart­ment of Mechan­ical and Indus­trial Engi­neering in the spring after spending eight years at Impe­rial Col­lege London, where her research spanned a broad range of inves­ti­ga­tions. She uses in vivo exper­i­men­ta­tion and com­pu­ta­tional mod­eling to study topics ranging from how bones adapt to increased mechan­ical load to what makes the bones of patients with brittle bone dis­ease more sus­cep­tible to frac­tures. According to She­fel­bine, bone is gen­er­ally both tough and strong, two traits not com­monly found together.

To under­stand how dif­ferent species’ bones have evolved over time, she has studied the bones of ani­mals including ele­phants and Etr­uscan shrews, whose thigh­bones are the size of a fin­ger­nail clipping.

She also looks at how bone develops over the course of a single individual’s life­time; this includes working with emus, which reach full matu­rity in just 18 month. “During this time they change their bone struc­ture and the way they walk,” she said. “It’s a really inter­esting model for trying to under­stand how that process happens.”

This work was inspired by exam­ining the bones of human chil­dren with cere­bral palsy, a neu­ro­log­ical dis­order that affects an individual’s ability to con­trol his or her skeletal muscles.

We asked how does the way the person walks influ­ence the way the bone grows,” She­fel­bine said. “The future goal is to pro­vide ther­a­peutic strate­gies to put the proper loads on the bone to make sure they are growing correctly.”