Limb lengthening device developed by Rice University students

Undergraduate students at Rice University have designed a self-adjusting, automated device for patients undergoing distraction osteogenesis to correct bone deformities that leave one limb shorter than the other.

In collaboration with Shriners Hospital for Children in Houston, the engineering students designed LinDi, an automated linear distractor for children, as part of their senior design capstone project, according to a press release. The device is powered by a battery-operated motor that automatically adjusts the device almost 1,000 times a day. The motor eliminates the manual manipulation aspect of current distractors that require the patient to turn a screw at least four times a day to adjust the device and makes the new bone growth a more natural and continuous process.

“The problem with the current device is that there’s a lot of room for error,” Raquel Kahn, a student on the project team, stated in the release. “You can imagine that one might forget to turn it once, or turn it the wrong way, or turn it too much. And a lot of problems can arise in the soft tissue and the nerves surrounding the bone. That’s the limiting factor of this process. But LinDi implements a motor to make the distraction process nearly continuous.”

The device also incorporates a built-in force-feedback loop that protects fragile tissues and nerves from being overstressed. If the load on the tissue is too high, the device will automatically shut the motor off.

“The process of limb lengthening — essentially creating a localized mini-growth spurt — works well for bones, but is very hard on the soft tissues such as nerves and blood vessels,” Gloria Gogola, MD, an orthopedic surgeon at Shriners, stated in the release. “This team has done an outstanding job of designing a creative solution. Their device not only protects the soft tissues, it will ultimately speed up the entire process.”

Through Shriners, the students were able to perform short-term animal testing to develop the device. Although they will be graduating soon, the students expect another team to continue their work with LinDi.

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