Foot Drop System

Award winning product design company, Industrial Design Consultancy (IDC), has just developed an advanced medical device to help people with certain neurological conditions walk again.

The XFT Foot Drop System delivers electrical pulses to counteract the effect of foot drop (the dropping of the foot due to peroneal nerve damage or leg muscle paralysis) in patients with neurological problems. The system includes a small Functional Electrical Stimulation (FES) device which is strapped onto the patient’s leg below the knee and sends electrical signals to the peroneal nerve (the nerve that controls the movement of the ankle and foot), stimulating the muscles to raise the foot at the appropriate time so the patient can walk. This works in combination with a foot sensor, which detects the walking rhythm and helps regulate a normal walk.

IDC handled product development from concept right through to production support. Initially, the team focused on research with both patients and doctors to understand how the product would be used. For doctors, a key element was setting up the device for patients, so the product needed to be easy to assemble and disassemble, with the electrical stimulator, electropad and cable integrated into the strap.

Patient research also identified several areas of focus. The device would be used by patients with different neurological conditions; including stroke patients who may have lost control down one side of the body. This meant that in designing the product, IDC needed to ensure the device could be strapped on using only one hand. Patient comfort was also a key issue and led to careful consideration of materials for maximum breathability, durability and design comfort. IDC took inspiration from sports products such as knee supports which used the latest high-tech materials; this research also demonstrated how the product would behave during use.

IDC designed the strap with an embedded plastic ‘C’ shape strip to help it hang on the leg while the buckle was being clipped. This meant it could be fastened using just one hand. A velcro adjustor could also be used to adjust the strap length. The stimulator was integrated into the strap, along with the wires which connected to electropads. Part of the design challenge was in integrating all the system elements within the strap. This was achieved by including a holder for the stimulator to clip into, and a concealed zip pocket to hide all the cables and allow easy assembly/disassembly.

Another challenge was to ensure that the electropads would be in the right position to stimulate the peroneal nerve each time the strap was fitted. The design meant that the electropads could be customised to the best position for each user. This was done by moving the velcro-backed electropads along the strap, so that when the strap was worn, the electropads would be in the optimum position for the peroneal nerve.

IDC produced several prototypes of the system, using different materials, before the look and structure were finalised. There were four components of the system, with the stimulator, strap and electropads, foot sensor and remote control. These were all designed to have the same family style.

Marc Tanner, IDC’s Head of Design, comments, “We are delighted to have produced the Foot Drop System for XFT. This is the second medical product we have developed over 2011 for XFT and we have overcome many design challenges to produce a device that is highly innovative but also budget-conscious.”

After extensive clinical and user trials, the XFT Foot Drop System is now being manufactured with the ongoing support of IDC. XFT’s Product Development Manager, Jackey Woo, explains, “Combined with IDC’s excellent design, wehave turned this FES device into a high-tech advanced machine. We already have SFDA certification in China, where the product has been used in more than 10 cities. We are now ready to apply for CE and FDA certification, for sales across the world.”