(Image: Erik Jepsen/University of California San Diego)

Nine out of 10 amputees in the world don't have access to a proper prosthetic. The startup company, LIMBER Prosthetics & Orthotics, Inc. aims to do something to address this problem by 3D printing complete one-piece structurally sound prosthetic limbs.

LIMBER started as a grassroots, student-driven research effort at University of California, San Diego, taught by structural engineering Professor Falko Kuester.

They were trying to improve the process for building a custom prosthetic. The traditional method requires prosthetists who are like sculptors. They carve a model of the residual limb by hand — a time-consuming process that is expensive and can’t be easily scaled with current mass manufacturing techniques.

That’s when Kuester approached one of his Ph.D. students, Luca De Vivo Nicoloso, with the idea of printing prosthetics.

A year later, De Vivo, who was then a teaching assistant in the class, Joshua Pelz, who was then a Ph.D. student in the class and Herb Barrack, a certified prosthetist and orthotist with more than three decades of experience, decided to form the company.

“To begin, we scan the remaining leg with the facial recognition camera on the iPhone (model 10 or later). With that scan, we construct a model of the limb,” said Pelz. But, added De Vivo, “It’s not only the scan that gets used to design the missing limb — we use that as a starting point for the geometry. A certified prosthetist on our team takes manual dimensions to supplement the scan, and only then designs the prosthetic leg. The prosthetics need to be personalized to account for individual issues. So, it needs to be designed by a person with knowledge about what a prosthetic limb should look like for that specific person.”

“We start when an amputee goes into a prosthetic clinic, or, in the case of developing countries, a rehabilitation or medical center. Preference is always that a prosthetist collects 3D scan and manual measurements (often possible even in underserved/developing countries). If this is not possible, LIMBER can train someone with anatomical/medical knowledge to collect the data we need,” said Pelz.

According to the team, the data is sent to the LIMBER cloud, where a series of design technicians and certified prosthetists retrieve it and design the personalized limb. The design is then sent to their 3D printing facilities, where their technicians print it, post-process it, package it, and ship it to the prosthetic clinic or medical center where the patient and the prosthetist are located.

“The last stage of the work is when the prosthetist or medical specialist fits the leg. Although good starting data will allow us to get close, there may be cases where dynamic alignment is necessary. If so, thermoforming can be used with our technology to make adjustments,” added Pelz.

This is a process that, in the U.S., can be done in one to two days from the moment the patient gets scanned, to the delivery. We have also done it across borders from San Diego to Ukraine in less than seven days. This is something that can be world-reaching,” said De Vivo.

LIMBER’s business plan is two-fold. The company plans to sell its personalized prostheses in developed countries while providing its services for developing countries at discounted prices or for free. “We feel the best way to accomplish that, is working with local institutions — people on the ground who know the community, the culture, the needs of their population. For example, we are working in Mexico with community members in a local Rotary Club,” said Pelz.

To date, they’ve printed legs custom designed to fit 15 different people — and did not have to re-print any of them. Four required slight alignment adjustments and two required slight socket fit adjustments, which were easily made by a prosthetist using a heat gun with a specially designed applicator.

The goal for LIMBER is to be selling 3D-printed prosthetic limbs in the U.S. in the first quarter of 2024.

This article was written by Ed Brown, Associate Editor, SAE Media Group. For more information, visit here .