Stance Control Knee Ankle Foot Orthoses

(KAFOs)

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.

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.

Stance Control Overview

Benefits of SCOs over Conventional KAFOs:• Decreased gait anomalies during swing phase

VaultingHip hikingCircumduction

• Decreased pulmonary/cardiac stress• Esthetic gait pattern

Stance Control Overview

Primary reasons that Stance Control Technology is contraindicated:

• Moderate to severe spasticity of the hamstrings• Permanent knee flexion > 15° (contracture or bony block)• Body weight > 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

SCO Study Reference Slides

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.

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

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.

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.

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.

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.