Knee stability in an AFO Standard Metal AFO: 375 in. lbs. 60% reduction In Quad torque
Types of ankle bracing
Powered Gait Orthoses Hydraulic Actuation (Seireg et al 1981) Five DOFs (2 at hip, 1 at knee, 2 at ankle) Good and simple design and analysis Bulky and unusable because of the current state of technology linear DC motor (Ruthenberg et al 1997) 4 bar linkage and CAM system One DOF run by a Battery pack and control system Mechanized hip and knee with cam-modulated linkage for knee function Peak power usage ~ human walking May be a practical means for paraplegic gait?
Functional Electrical Stimulation Can re-animate paralyzed muscles External or internal electrodes User triggered with switches. How else? Most are open loop, but reflexes not necessary for rhythmic motions. Problem because cutaneous nerves are stimulated first. Also larger motoneurons have lower threshold.
Functional Arm Orthoses See also pp. 319 yellow
Correcting muscle Atrophy Atrophy is the loss of muscle mass Present methods for preventing atrophy Myoplasty Myodesis Implantable devices Continuation of Class 5 on muscles
Elasticity (All or none) Time scale
Muscle adaptation Two types : fast and slow or twitch and tonic white and red Interchangeable Fibers extend full length of muscle
Bion (Loeb et al.) BIONs are individually addressable, single channel stimulators that can be injected in or near muscles and nerves to treat paralysis, spasticity and other neurological dysfunctions. BIONs receive power and digital commands from an externally worn RF transmitter coil and generate precisely timed, current-regulated electrical stimulus pulses.
System for functional electrical stimulation Non-polarizable High surface area Prototypes of Bion2 have sensing capability for acceleration, & proximity. Galvani discovery of electricity
The BION™ A system using BIONs consists of a personal computer, a transduction coil, and the associated implantable BIONs A computer can control up to 256 BIONs at a time What are present uses for the BION? 560 KHz carrier, need 20 Hz stim E Storage in body’s capacitance
Flow Charts of BION Operation Implantable Device
Comparison of Std. FES and the BION™ System Similarities
Both use magnetic fields to activate the implants
Both are used to stimulate muscle contraction
Differences Implantable FES BION™
Not battery powered
External computer controls BION™ activation
Battery Powered Switch to turn power on or off
Idea for Bion in Preventing Atrophy Currently bions are controlled by an outside source, the personal trainer Goal would be to have the body control the computer that controls the bions. The trick would be creating a component that would be able to sense/detect an action potential along the severed nerve and use that signal to activate the bions.
Some Applications Shoulder Subluxation
Hand assist devices
Without a glove May be difficult for a paralytic hand to don.
Ankle Exercisor Drop foot is due to central paralysis; injury, I.e. PTT; osteoarthritis; Charcot foot.
Range of Motion Ankle Rehabilitator An inverted joystick interface to computer.