Stance Control Knee Ankle Foot Orthoses (KAFOs)

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Stance Control Knee Ankle Foot Orthoses(KAFOs)
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Stance Control Overview

• Stance Control Orthoses vs. Conventional KAFOs
• SCOs differ from Conventional KAFOs in that they
  allow for knee flexion during the swing phase and
  locking during stance phase.

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Stance Control Overview

• Why Stance Control?
• A traditional KAFO can lock the knee in full
  extension, which provides stability but also
  causes patients to ambulate with a gait deviation
  that can lead to overuse injuries due to
  compensatory measures taken by the patient to
  ambulate. This in turn requires more energy to
  get from point A to point B.
• A stance control orthosis (SCO) allows the knee
  to bend during the swing phase of the gait cycle
  and blocks knee flexion for stability during the
  stance phase. By allowing the knee to bend during
  swing phase, SCOs allow a more normal gait, which
  may reduce secondary complications from gait
  compensations, and allow the patient to walk with
  less effort.

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Stance Control Overview

• Benefits of SCOs over Conventional KAFOs
• Decreased gait anomalies during swing phase
• Vaulting
• Hip hiking
• Circumduction
• Decreased pulmonary/cardiac stress
• Esthetic gait pattern

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Stance Control Overview

• Primary reasons that Stance Control Technology is
  contraindicated
• Moderate to severe spasticity of the hamstrings
• Permanent knee flexion gt 15 (contracture or bony
  block)
• Body weight gt 300 lbs
• Cognitive inability to understand gait training
• Inability to advance limb because of weak hip
  flexors or lack of substitute
• patterns to advance the limb in swing phase
• Lack of hip abductors in bilateral patients

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SCO Study Reference Slides
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KAFO Use

• KAFOs have historically had a rejection rate of
  between 58 and 79, and over 40 of users state
  that they are 'dissatisfied' with their orthosis.
  1
• "Many users develop opinions on the device during
  the first two weeks, and up to half of braces
  will be rejected in this same period." (Fisher
  and McLellan 1989 Butler et al. 1983).1
• "In the United States, approximately 989,000
  people wear KAFOs (Russel et al. 1997).2
• 1. Consumer opinions of a stance control knee
  orthosis, Katherine A. Bernhardt, et al.
  Prosthetics and Orthotics International, December
  2006 30 (3) 246-256
• 2. Gait Changes over time in stance control
  orthosis users, Steve E. Irby, et al, Prosthetics
  and Orthotics International, December 2007
  31(4) 353-361.

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Important Factors for Assistive Devices

• "A panel of six consumer experts with mobility
  impairments ranked 15 different factors related
  to assistive devices in general. The three most
  important factors were effectiveness,
  operability, and dependability." 1
• A survey conducted with 20 Dynamic Knee Brace
  Systems (such as the Sensor Walk), had few
  concerns about effectiveness, operability, and
  dependability.
• 1. Consumer opinions of a stance control knee
  orthosis, Katherine A. Bernhardt, et al.
  Prosthetics and Orthotics International, December
  2006 30 (3) 246-256

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Results of a study applying a Stance Control
Knee Orthosis (SCO) in place of a KAFO. 1

• On the braced limb The stance-control mode
• Showed a near-normal knee flexion wave in swing
• Reduced pelvic retraction and rotational
  excursion
• Improved hip power generation
• There was a trend towards improved energy
  efficiency in stance-control mode
• 1. Gait Evaluation of an Automatic Stance-Control
  Knee Orthosis in a Patient with
  Postpoliomyelitis, Jackie S. Herbert, et al. Arch
  Phys Med Rehabil Vol 86, August 2005.

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Results of a study applying a Stance Control
Knee Orthosis (SCO) in place of a KAFO.1

• On the non-braced limb the stance-control mode
• Allowed for the elimination of vaulting
• Reduced abnormal ankle and hip power generation
• Increased knee power absorption
• Provided for more typical quadriceps activation
• 1. Gait Evaluation of an Automatic Stance-Control
  Knee Orthosis in a Patient with
  Postpoliomyelitis, Jackie S. Herbert, et al. Arch
  Phys Med Rehabil Vol 86, August 2005.

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Results of a study applying a Stance Control
Knee Orthosis (SCO) in place of a KAFO.1

• The SCO/KAFO study concludes that use of a SCO
  could return gait kinematics, power generation
  and absorption patterns toward a more typical
  pattern, while also offering greater energy
  efficiency during ambulation. 2
• 1. Gait Evaluation of an Automatic Stance-Control
  Knee Orthosis in a Patient with
  Postpoliomyelitis, Jackie S. Herbert, et al. Arch
  Phys Med Rehabil Vol 86, August 2005.

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Efficiency of SCOs

• An efficiency study led by Kenton Kaufman, PhD,
  from Mayo Clinic, showed that the difference in
  oxygen consumption for a person using a locked
  versus an unlocked knee was 1 ml/kg/mm.
• For an able-bodied adult subject this difference
  would roughly translate into a 10 difference in
  walking speed. 1
• 1. Energy-Efficient Knee-Ankle Foot Orthosis A
  Case Study, Kenton R. Kaufman, PhD, et al.
  Journal of Prosthetics and Orthotics 8(3) 79-85,
  1996.