KAFO

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What is a KAFO ?

• KAFO (Knee-Ankle-Foot Orthosis Long Leg Brace)
• - To prevent an abnormal motions and anomaly
  and to correct for the proper
• weight transfer

Drop ring lock
Bail lock
Conventional KAFO
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• Limitations of the Conventional KAFO
• 1) Limited knee joint control
• causing circumduction, hip hiking,
  contralateral vaulting
• 2) Alignment is required for the stability in
  stance
• 3) Heavy weight
• ? increase energy consumption

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Objectives

• Ideal KAFO sufficient weight support in
  stance and knee flexion in
• swing
• To develop a new light KAFO which satisfies both
  stability in stance and
• knee flexion in swing
• To evaluate the developed electro-mechanical
  KAFO by gait analysis
• and energy consumption

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Electromechanical KAFO

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Electromechanical KAFO
Electro-mechanical KAFO
KAFO control system
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Foot Switch Sensor System

• Force sensing resistor

• Determination of stance and swing by the foot
• contact situation
• Insole with foot switch sensors at the heel and
  the
• 2nd metatarsal head

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Electromechanical Clutch
- Mechanical wrap spring clutch - Maximum
static torque 28 Nm - Total weight 280 g
Over-running state
Driving state
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Assembly of Electromechanical KAFO

• Design of the connecting parts between the
  clutch and uprights of KAFO

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Clutch Control Algorithm
Open / off Close / on
Clutch
Foot switch
Heel
Meta
RC Motor forward
RC Motor reverse
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Electromechanical KAFO
Controlled-knee gait
Locked-knee gait
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Gait Analysis
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Marker Set Davis Protocol

• Markers
• - sacrum
• - anterior superior iliac spines (ASIS)
• - greater trochanter
• - 1/3 of the femur
• - lateral epicondyles
• - tibias
• - lateral malleolus
• - fifth metatarsal heads
• - heels.

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Electromechanical KAFO Normal

• Locked-knee gait

Controlled-knee gait
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Knee Flexion Angle Normal
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Knee Flexion Moment Normal

• Controlled-knee gait

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Electromechanical KAFO Polio Patients
Controlled-knee gait

• Locked-knee gait

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Knee Flexion Angle Polio Patients
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Energy Consumption Experiments
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Results Polio Patients
(plt0.05)
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Conclusions
1. The new electromechanical KAFO is helpful to
provide patients with partial or complete
paralysis of the lower extremity with both
stability in stance and free knee motion in
swing, efficiently in energy transfer.
2. In controlled-knee gait for patients with
Grade 2 or higher in manual muscle tests,
reasonable amount of knee flexion during the
swing phase could be achieved as in the normal.
Free-knee motion of the KAFO during the swing
phase of the gait increased walking speed and was
significantly more efficient in energy transfer
than locked-knee. 3. More detailed clinical
experiments are currently performed on other
patients. 4. This kind of control mechanism
could be applied to all future designs of KAFOs
and other orthotic interventions in the lower
extremity.
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Thank you