Evaluating a New Knee-Ankle-Foot Brace to Improve Gait in Children With Movement Disorders

Objective

The purpose of this protocol is to evaluate several configurations of a prototype Extension
Assist Knee-Ankle-Foot Orthosis (EA-KAFO) in patients with cerebral palsy (CP), muscular
dystrophy (MD), spina bifida (SB), or incomplete spinal cord injury (iSCI) who have knee
extension deficiency. Three forms of assistance will be provided at the knee joint including
a passive-damper component, functional electrical stimulation (FES) to the quadriceps, and a
motorized assist. One form will provide variable resistance at the ankle joint which can also
promote knee extension. These will be compared to traditional bracing which typically
improves crouch by blocking some or all motion at one or both joints. We hypothesize that all
assistive configurations will improve gait alignment and performance compared to the
non-assisted conditions. We further hypothesize that a best solution for each participant
will exist, but may vary across subjects due to the heterogeneity of these movement
disorders. Preliminary data on brain activation using EEG will be collected during all
walking conditions.

Study population

Thirty (30) subjects, age 5 and above, diagnosed with crouch gait from diplegic CP, (30)
subjects, age 5 and above, with knee extension deficiency from MD, SB, or iSCI (15 from each
group) and 10 age-matched healthy volunteers will be recruited.

Design

This protocol will evaluate an EA-KAFO prototype consisting of a custom fabricated brace
combined with a modular knee joint with three modes of operation: hinge (no assist), a
passive spring-damper, and an active motorized assist. Since crouch can also be precipitated
at the ankle, the orthotic ankle joint has an adjustable dynamic resistance (ADR) mechanism
that can be locked (passive assist) to simulate a standard brace, free, or provide variable
resistance to assist knee extension. Additionally, we will combine quadriceps FES with the
hinge and the passive damper to create two hybrid configurations. The hinge and the passive
damper (Ultraflex ) knee modules, and ADR ankle brace are FDA-approved (Class I),
commercially available devices. The active motorized joint module and the two hybrid
configurations have been evaluated by the FDA as non-significant risk to human subjects
(Appendix F). Healthy controls will come for one visit, and participants with movement
disorders will complete 6-10 visits: 1) initial assessment and casting for custom leg brace;
2) EA-KAFO configuration; 3) initial data collection and practice; 4-5) accommodation to
brace configurations; 6) final data collection. Additional accommodation visits may be added
if necessary, up to the maximum of 10 total visits. Motion capture, force plates, and
electromyography (EMG) will be used for gait analysis while electroencephalography (EEG) will
measure brain activity during walking.

Outcome measures

The primary outcome is the amount of knee flexion during gait. The optimal solution for each
individual will be that which provides the greatest reduction in peak knee angle. Secondary
outcomes will include gait speed, knee extensor moment, and EEG activation profiles.

- INCLUSION CRITERIA:

- Age 5 years and above

- Either a healthy volunteer, have crouch gait with a diagnosis of spastic diplegic
cerebral palsy, or have lower extremity weakness resulting in gait pathology from a
diagnosis of muscular dystrophy, spina bifida, or incomplete spinal cord injury.

- Able to understand and follow simple directions based on parent report and physician
observation during history and physical examination.

- Able to provide verbal/written assent.

- Less than 5 degrees of knee flexion contracture with hip extended in supine position.
Hamstring contracture as assessed by straight leg raising test does not limit ability
to participate in the study.

- Less than 10 degrees of plantar flexion contracture in neutral foot alignment.

- A measured foot-thigh angle of -10 to 25 degrees in prone position.

- Diagnosed with knee extension deficiency as indicated by a crouched posture during
gait lacking at least 20 degrees of knee extension at mid stance during walking as
assessed visually, knee extensor muscle weakness which prevents full extension of the
limb, or reliance upon braces or other aids which lock the knee during walking. (The
exact level of knee extension deficiency, or crouch, will be quantified after
inclusion using gait analysis.)

- Able to walk at least 10 feet without stopping with or without a walking aid

- Agreement to not drink caffeine for 24 hours before each EEG assessment (CP only)
visit because it can modify brain activity

EXCLUSION CRITERIA:

-Any neurological, musculoskeletal or cardiorespiratory injury, health condition, or
diagnosis other than cerebral palsy, muscular dystrophy, spina bifida, or incomplete spinal
cord injury that would affect the ability to walk as directed for short periods of time.

ADDITIONAL EXCLUSION CRITERIA FOR INDIVIDUALS WITH CEREBRAL PALSY:

-A history of a seizure in the past year.