PIM: a new approach to designing (stylish) orthopedic shoes
When you think of an orthopedic shoe, you don’t often think of the height of fashion. In fact, many people have even ignored doctor’s guidance to wear orthopedic footwear because of how unfashionable the medical shoes can be. Well, fortunately for all of us with foot ailments, that could be changing thanks to advanced design technologies and 3D printing.
This incoming era of stylish orthopedics is in part thanks to Daniel Petcu, a footwear engineer who has developed a design approach called Pedorthic Information Modeling (PIM), which leverages parametric design principles to generate custom, 3D printable orthopedic footwear. The technology is inspired by architecture’s Building Information Modeling (BIM) and uses Rhino 3D’s Grasshopper software to create digital models of orthopedic shoes that are—if I do say so myself—quite aesthetically pleasing.
The PIM design process starts with a digital footwear model, which can be adjusted in terms of foot anatomy, structure and stiffness. The code created by Petcu controls these various parameters based on the wearer’s requirements. For example, one of these parameters, called Gradient Stiffness, adjusts the stiffness across the shoe’s design to accommodate different foot issues and orthopedic functions, like for patients with diabetic feet or for children who have fallen arches in their feet.
Beyond the design program, 3D printing has been integral to Petcu’s project, as the technology allows for custom shoes to be fabricated with efficiency and precision. In his work, he has primarily been working with flexible filaments, like Ultrafuse TPUs and Varioshore TPU, and extrusion-based 3D printing technologies. TPU, which offers a combination of flexibility, durability, biocompatibility and comfort, proved to be an ideal material for footwear.
Rhino3D’s Grasshopper parametric design tool has made it possible to recreate the gradient stiffness in a 3D print. “The G-code for 3D printing is processed through Grasshopper, allowing Petcu to control the rigidity of the shoe’s components directly from the design code, resulting in a shoe optimized for both comfort and function,” Rhino3D explains. This capability would be challenging if not impossible using traditional slicing, which could interrupt the changes in stiffness. From the patient’s perspective, 3D printing the footwear rather than buying orthopedic shoes “off the rack” gives them greater aesthetic control, with various color and texture options to choose from.
Ultimately, parametric design and 3D printing are allowing Petcu to help advance the field of orthopedic footwear, which has well established processes and norms. He admits that he did face skepticism initially from the orthopedic community, however the transformative power of digital design and additive technologies in the field can no longer be overlooked. In fact, Petcu’s PIM project has been presented with acclaim at major care industry events like OTWorld and AM footwear event FootPRINT3D. As he continues to develop and refine the design and production processes, his next goal is to develop an orthopedic model for patients with Charcot-Marie-Tooth, a nerve condition that can lead to foot problems and deformities.
3D printing and orthopedics have been linked in recent years, but most projects we’ve seen in the footwear space have tended to focus on the production of custom insoles or midsoles. Petcu’s project definitely goes a step further, leveraging parametric design and 3D printing to create the entire shoe, for a unique silhouette and avant-garde style that even the biggest shoe snob would be hard-pressed to pass up.
