Project brief
Blatchford, a global leader in mobility solutions focussing on breakthrough technologies and services, have been manufacturing prosthetics and orthotics for over 129 years. With an emphasis on biomechanical design principles, Blatchford’s key objective is to ensure that their prosthetic and orthotic work syncs perfectly with the human body.
The Orion and Linx are two of Blatchford’s most popular prostheses. The award-winning Linx system is the first ever intergraded prosthetic limb combining various microprocessors and several situational awareness sensors across the knee and ankle to continuously collect data on the user, activity and terrain. This data is used to adjust the limb for ease of use, enhancing safety and stability, mimicking a human limb.
To protect the prosthesis from the elements, wear and tear, and to provide some level of kneeling comfort for the wearer, Blatchford proposed the development of a cosmetic cover that could be applied to either prosthesis.
Simon Russell Taylor, Head of Continuous Improvement and Project Champion on the development of the cosmetic cover notes that the history of the development of the cosmesis for prosthetic limbs has been an evolutionary one. Today’s wearers are both more active and more comfortable with displaying their personalised prosthetics.
Once bulky and constricting, today’s cosmetic covers need to be smaller, lighter and ideally customised to the wearer and more functional. They are still required to offer the aesthetics of a normal limb under clothing, but also need to allow the wearer to participate in an array of activities without encumbrance.
Challenges
With two prosthetic systems requiring cosmetic cover protection, Blatchford R&D first had to first ascertain what universal shape would fulfil the protective, aesthetic and functionality needs of both.
The design team set about developing several prototype models of the bulk shape to enable comparisons with competitors, establish design ergonomics and ensure manufacturability.
Shape development commenced with 3D scanning of the core of the prosthesis to provide the dimensions for the CAD. Once the cover shape and approximate dimensions had been agreed and the CAD had been produced, the next step was to explore potential materials and production technology. Having previously worked on several prototyping projects with Paragon Rapid Technologies, Blatchford hoped that their additive manufacturing (3D printing) capabilities would enable concise, quick and cost effective manufacture.
Materials exploration was led by Paragon. Given the required amount of flexibility and the range of movement the cosmetic cover was likely to be subjected to, elastomers, with their tactility and memory seemed likely solutions.
The team began a search for materials that would pass an extensive series of tests including donning and doffing, temperature and flammability testing, co-friction testing (to ensure trousers did not bunch up over the limb when the wearer moved), and durability testing. The materials making it to the play offs, so to speak, were then subjected to lengthy wearer trials amongst amputee focus groups.
Results
After several months of rigorous testing, Clear Flex 95 emerged as the ‘clear’ winner, offering the levels of robustness and flexibility required by both Linx and Orion wearers. For aesthetic purposes, the resin was dyed black before casting.
There were several problems with sourcing sufficient quantities of the Clear Flex 95 and Paragon’s R&D department returned to the drawing board. They found an alternative material in the form of M3184.
This black, fire retardant and self-extinguishing resin is slightly more rigid but also possesses vibration dampening properties and is very quick to process, enabling savings to be made in terms of both time and money.
“The process has not been without its challenges,” says Simon Russell-Taylor. “The developed process does now allow us the opportunity to cast thin shells with appropriate levels of wall thickness and customisation without compromising durability. The cover is proving to be hugely popular and has become an integral step in the overall development of cosmesis.”
Blatchford and Paragon continue to work closely together to develop new products that will ultimately better the lives of the end-users.
