D2.1 Requirements and Specification - CORBYS

D2.1 Requirements and Specification
biomechanics of walking fall into four functional categories:
� deformity (muscle and joint contractures on allowing for a sufficient passive mobility)
� muscle weakness (insufficient muscle strength)
� impaired control (sensory loss, spasticity: selective control is impaired, primitive locomotor patterns
emerge: mass flexion and mass extension in all three joints, muscles change phasing, proprioception
is impaired)
� pain
The CORBYS gait rehabilitation system should be concerned only with the impaired control and muscle
weakness. The other impairment categories should be treated in other ways (physical therapy, casting and
medical treatment). The general approach in walking rehabilitation should be either to train a “normal”
walking pattern, or, if muscle weakness or muscle contracture will not allow a normal pattern, a
compensatory, “optimised” movement patterns is permitted (or adequate orthotic aids are given) in order to
achieve functional walking.
The following section addresses the four most frequently occurring gait deviations due to impaired control,
describes which and how principal walking mechanisms are affected and demonstrates how CORBYS system
should behave to restore normal walking pattern.
4.1.2.2.1 Toe walking
Figure 2: Toe walking in sagittal plane
Principal characteristics of toe walking are:
� initial contact with forefoot (metatarsals joints)
� pronounced plantar flexion / dorsiflexion deficit in ankle throughout the gait cycle
� the heel touches the ground in mid stance or may even remain above the ground throughout the stance
phase; likewise, in terminal stance a premature heel rise is common
� increased knee and hip flexion throughout the gait cycle
They impose:
� insecure initial contact
� propulsion is achieved predominantly by rapid hip extension instead of forceful extension in all joint
CORBYS system should restore:
� adequate ankle dorsiflexion prior to contact for proper heel contact and weight transfer (this may
normalise the movement in other joints as well)
� forceful extension in ankle, knee and hip during push off to assure normal propulsion
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