Technique Advancements in Foot Orthosis Design Provide New Insight

Technological advances in orthotic technology have caused a shift in traditional orthotic paradigms, according to Roy H. Lidtke, DPM, CPed, and director for the Center for Clinical Biomechanics at St. Luke’s Hospital in Cedar Rapids, Iowa. Lidtke presented his findings at the 2009 Pedorthic Footwear Association (PFA) Symposium in Grapevine, Texas.

According to Lidtke, the traditional paradigm for pedorthists and orthotists is to capture the physical shape of the foot, create a positive of the foot, modify it and then vacuum press a uniform thickness sheet. However, according to Lidtke, a single uniform thickness orthosis will respond in a single uniform way.

“A static captured shape is somewhat limited in its response to a dynamic foot functioning on top of it,” Lidtke said at the symposium.

Lidtke noted that current software has the ability to perform numerous tasks and modifications that could lead to diverse and hopefully, better outcomes. Lidtke noted in his presentation, practitioners have the ability to take a static 3-D object and make it dynamically responsive to the foot. Practitioners can change the dimensions and thickness of the orthosis with a touch of a button. Using their knowledge of biomechanics as well as their creativity with new technology, practitioners can ask themselves how they are going to manipulate the orthosis more effectively.

Pedorthists and orthotists are no longer limited by uniform thickness due to CAD/CAM software’s ability to capture 3-D images of the foot, coupled with computer numerical control (CNC) machines milling the orthotic device. Lidtke referred to this lack of limitation as one of the “subtle advances embedded in the larger technological advances of orthotics.”

Orthotics with inconsistent thicknesses will provide various reactions to loading during the gait cycle when using computer design and milling.

“If you mill the shell out of a 3-D block of material, your imagination is the only limiting factor,” Lidtke explained.

Lidtke believes pedorthists should provide new ways of thinking about foot orthoses. CNC milling of the shell opens up unlimited possibilities for orthosis design and manufacturing, Lidtke explained at the symposium. Pedorthists and orthotists should think about what they want the orthosis to do and then manipulate the design using technological advancements to achieve that goal.

Further advancements, according to Lidtke would include the use of a robot system with a force feedback mechanism to help direct a surgeon’s hand. This could be a useful tool when a patient is undergoing foot or ankle surgery.

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