The rapidly developing area of 3D printing has already seen a number of exciting and interesting applications in the field of prosthetics. A notable example of this is the Open Bionics low cost hand being developed by Joel Gibbard, the recent winner of the P&O Award for Prosthetic or Orthotic Product Innovation.   

New development

A recent development is the work being undertaken in America into the potential application of 3D printing in terms of producing a whole prosthesis.  William Root, an industrial designer and recent graduate from the Pratt Institute in New York City, has developed a system to 3-D print super-lightweight prosthetic legs with "stealth styling".

Called Exo, the prosthetic concept combines aesthetics and biomechatronics, while seeking to meet the preferences of amputees.   In an online article for Wired.com, He noted “In my research it became clear to me that there is a lot wrong with how designers typically try to approach a prosthetic limb and how the industry goes about making prostheses.  Prostheses are not aesthetically pleasing, are extremely expensive and difficult to produce.”

3D modelling

His improved process starts by making a scan of the patient’s anatomy.  He envisages using a technology developed from MIT’s Biomechatronics lab called FitSocket which uses an array of pressure sensors to gauge the softness or stiffness of a patient’s remaining tissue.  With this data, a nearly perfect socket can be manufactured.  Using the same data to extrapolate a 3-D model of a patient’s full leg, this is turned into a triangulated mesh.  “It has the maximum strength for the least amount of material with the added benefit of looking really slick,” says Root.  A stress analysis tool is used to determine weak-points on the model and to increase the mesh density of the structure to compensate.  At present, the model s not fully weight bearing and further analysis of the weight distribution and point loads will be needed to create a fully functioning limb.

The resulting model is a jet black prosthetic made from sintered titanium powder or high-strength plastic. "Prosthetic limbs are stigmatized because they are (can be) so inhuman" says Root.  In his view, legs made from flesh-coloured rubber are a symptom of a thought process where prosthetics are considered mass produced products  “Each leg needs to be as unique as its owner.” He envisions future iterations of Exo where colours or patterns of the mesh could be modified to suit the wearer’s personal sense of style.

This is an early design and clearly there will be several hurdles along the way, not least of which will be the ability to incorporate knee and ankle joints from traditional prosthetic suppliers. The need to be fully weight bearing may also lead to compromises in the design that could impact on cost and appearance.  However, the idea of concepts such as this serve to highlight the potential benefits of a better looking and lighter limb. As noted in the article, as 3D printers become more widespread and 3D printing technology advances, the costs and have nowhere to go but down.