LEIPZIG, Germany — The human hand is a complex system of 27 bones, 33 muscles and 22 axis movements. When the hand is put into numbers, it becomes easier to recognize the complexities biomechanical engineers face when developing upper extremity prostheses. According to Michael Shäfer, president, Pohlig GmbH, replacing such fine motor skills with advanced upper extremity technology has been a slow-moving process.
The goals of an upper extremity prosthesis are to repair body image, regain a visual identity and most importantly, restore function. Restoring function has become more difficult since the evolution of hand held digital devices.
“If we look at the digital media we see huge storage spaces in small sizes,” Shafer told the audience at the ORTHOPÄDIE + REHA-TECHNIK 2012 International Trade Show and World Congress. “O&P did not advance as quickly.”
Multi-articulating hand systems such as the i-Limb, BeBionic and the Michelangelo hand have made great strides implementing adaptive gripping for daily living activities. But even these high profile devices have fundamental limitations. The thumbs are difficult to maneuver forcing the user to use their other hand for repositioning. If the thumb had more freedom, the user’s other hand could possibly be used for other activities. The amount of force placed on an object during grip has yet to be perfected, but is improving. Despite steps in the right direction, smartphones, tablets and other handheld devices are technologically advancing at warp speed, continually changing and integrating new systems and interfaces. More so than ever before, the world is trending in a direction that requires more functional hands and fingers, Shafer said.
Shäfer M. Function: Arm prosthetics in focus. Presented at the ORTHOPÄDIE + REHA-TECHNIK 2012 International Trade Show and World Congress. May 15-18. Leipzig, Germany.