A N I N T R O D U C T I O N A N D R E V I E W O F L I T E RAT U R E

K A I T LY N R I S N E S , S P TC O L L E G E O F S T. S C H O L A S T I C A

C L A S S O F 2 0 1 6

THE PEDIATRIC ANKLEBOT

OBJECTIVES

• Gain a basic understanding of the design of the pediatric anklebot including intended population, uses, and design concepts.

• Review the literature in regard to the anklebot specifically and research regarding robotics in rehabilitation of the ankle.

• Discuss implications of technological advances for the field of rehabilitation.

WHAT IS THE pediAnklebot?• A robotic device developed at MIT

in 2011 to retrain the ankle of neurologically impaired children ages 6-10 years old.• Based on the theories of

neuroplasticity • What “fires” together “wires” together

• Reproducible movement can be provided in high repetition

WHY FOCUS ON THE ANKLE?

• The ankle functioning is important in order to have an efficient gait pattern

• Impaired ankle function is a frequent cause of limitation in ambulation in children with cerebral palsy. • Contractures and spasticity affect alignment and create an

imbalance in the involved limb. • The increase in plantarflexor muscular tone along with an

equinus foot are the largest sources of gait impairment.

Lacking push off or foot clearance– compensatory patterns emerge– physical structures become damaged– loss of function– possibility of surgery for correction

HOW IT WORKS?• Allows ankle range of motion (25o dorsiflexion,

45o plantar flexion, 25o inversion, 15o eversion, and 15o internal/external rotation) in three degrees of freedom relative to the shank during walking

• Provides active assistance in 2 of the 3 degrees of freedom, dorsi-plantar flexion and inversion-eversion, while rotation remains passive

• The kinematic design has 2 linear actuators mounted in parallel so if they push-pull in:• same direction plantar-dorsiflexion occurs• Opposite direction inversion-eversion occurs

• Torque produced cannot lift the weight of the child, only give cueing or supplemental support

SOFTWARE OF THE ANKLEBOT• Controller• Impedance controller with programmable torsional stiffness

and damping and programmable reference– guides the patient’s ankle• The time it takes the child to initiate movement and the degree of

stiffness in the device alters based on the child’s previous performance to allow individuality

• Serious Games• Goal-directed therapeutic "games" were designed to address

motor impairments• Track patient’s performance• Challenging patients to improve while keeping them

motivated– becomes harder when patient is doing well and slightly easier when having difficulty

• Serious games software…• First identifies the ability of the patient to move and point

with the ankle• Then independently adjusts the speed of the gameplay

and the size of the target• Knowledge of performance is used to challenge children

to improve their performance or, at the very least, maintain it (reducing any slacking).

• video

• Does adding mass to a limb significantly affect gait?• Study by Rossi et al. (2013) evaluated whether adding

masses up to 2.5 kilograms at knee level alters the gait kinematics• Subjects included 10 typically developing children and 8

children with CP with mild gait impairment• Gait was evaluated with and without weight by an expert

physical therapist and kinematic data was collected using an 8 camera video system

• The knee brace created some restriction to the joint moving, altering gait in the typically developing and CP subjects.• No further gait alteration with increased weight• Overall, adding mass up to 2.5 kg to the lower leg does not

alter lower limb kinematics • Study Limitations

ROBOTIC THERAPY AND THE ANKLE

• Study by Wu et al. (2011) investigating the efficacy of combined passive stretching with active movement training delivered by a rehabilitation robot. • A portable rehabilitation robot with computer game interface was used to

deliver the designed protocol and to display data the robotic device measured.• The robotic device was equipped with a torque sensor, a servomotor, and a

digital controller. It was connected to a personal computer for display and user interface.

• Subjects included 12 children with cerebral palsy (6 hemiplegia, 6 diplegia)• All had impaired ankle function that consisted of reduced ROM and reduced

selective motor control of his/her lower extremity. • Exclusion criteria

• Protocol• Sessions at laboratory 3x/week for 6 weeks including:

• 20 minutes passive stretching• 15 minutes assisted-active movement• 15 minutes of resisted active movement• 10 minutes of passive stretching

• Outcome assessment: performed before and after 6 week period• Clinical evaluations: Modified Ashworth Scale and Modified Tardieu Scale

for spasticity, the Pediatric Balance Scale, and the Selective Control Assessment of the Lower Extremity (SCALE)

• Functional evaluations included 6-minute walk and Timed Up-and-Go (TUG).

• Biomechanical measures were PROM, AROM, and muscle strength.

• Results• After the 6-week training period, participants showed significant

improvements in their ankle ROM and function with additional improvements in adjacent joints as well.• Statiscally significant improvements in active and passive DF, ankle stiffness,

and DF strength• No change in PF strength or ROM found• All showed improvements in balance• Covered longer differences in 6MWT• Improvements in the SCALE test specific to the ankle• No change in TUG measures before and after

QUESTIONS?

REFERENCES

Krebs, H. I., Rossi, S., Kim, S., Artemiadis, P. K., Williams, D., Castelli, E., & Cappa, P. (2011). Pediatric anklebot. IEEE ... International Conference On Rehabilitation Robotics: [Proceedings], 20115975410. doi:10.1109/ICORR.2011.5975410Meyer-Heim, A., Ammann-Reiffer, C., Schmartz, A., Schäfer, J., Sennhauser, F. H., Heinen, F., & ... Borggraefe, I. (2009). Improvement of walking abilities after robotic- assisted locomotion training in children with cerebral palsy. Archives Of Disease In Childhood, 94(8), 615-620. doi:10.1136/adc.2008.145458Michmizos, K. P., & Krebs, H. I. (2012). Assist-as-needed in lower extremity robotic therapy for children with cerebral palsy. In Biomedical Robotics and

Biomechatronics (BioRob), 2012 4th IEEE RAS & EMBS International Conference on (pp. 1081-1086). IEEE.Michmizos, K., Rossi, S., Castelli, E., Cappa, P., & Krebs, H. (2015). Robot-Aided

Neurorehabilitation: A Pediatric Robot for Ankle Rehabilitation.Rossi, S., Colazza, A., Petrarca, M., Castelli, E., Cappa, P., & Krebs, H. I. (2013).

Feasibility study of a wearable exoskeleton for children: is the gait altered by adding masses on lower limbs?. Plos One, 8(9), e73139.

doi: 10.1371/journal.pone.0073139

Wu, Y., Hwang, M., Ren, Y., Gaebler-Spira, D., & Zhang, L. (2011). Combined passive stretching and active movement

rehabilitation of lower-limb impairments in children with cerebral palsy using a portable robot. Neurorehabilitation And Neural Repair, 25(4), 378-385. doi:10.1177/1545968310388666Wu, Y., Ren, Y., Hwang, M., Gaebler-Spira, D. J., & Zhang, L. (2010).

Efficacy of robotic rehabilitation of ankle impairments in children with cerebral palsy. Conference Proceedings: ... Annual International Conference Of The IEEE Engineering In Medicine And Biology Society. IEEE Engineering In Medicine And Biology Society. Annual Conference, 20104481-4484.

doi: 10.1109/IEMBS.2010.5626043