A robot-based gait training therapy for pediatric population with cerebral palsy: goal setting, proposal and preliminary clinical implementation

Abstract

Background: The use of robotic trainers has increased with the aim of improving gait function in patients with limitations. Nevertheless, there is an absence of studies that deeply describe detailed guidelines of how to correctly implement robot-based treatments for gait rehabilitation. This contribution proposes an accurate robot-based training program for gait rehabilitation of pediatric population with Cerebral Palsy (CP).

Methods: The program is focused on the achievement of some specifications defined by the International Classification of Functioning, Disability and Health framework, Children and Youth version (ICF-CY). It is framed on 16 non-consecutive sessions where motor control, strength and power exercises of lower limbs are performed in parallel with a postural control strategy. A clinical evaluation with four pediatric patients with CP using the CPWalker robotic platform is presented.

Results: The preliminary evaluation with patients with CP shows improvements in several aspects as strength (74.03 ± 40.20%), mean velocity (21.46 ± 33.79%), step length (17.95 ± 20.45%) or gait performance (e.g. 66 ± 63.54% in Gross Motor Function Measure-88 items, E and D dimensions).

Conclusions: The improvements achieved in the short term show the importance of working strength and power functions meanwhile over-ground training with postural control. This research could serve as preliminary support for future clinical implementations in any robotic device.

Trial registration: The study was carried out with the number R-0032/12 from Local Ethical Committee of the Hospital Infantil Niño Jesús. Public trial registered on March 23, 2017: ISRCTN18254257 .

Keywords: Cerebral palsy; Exoskeleton; Gait; Rehabilitation; Robotic training; Therapy.

Fig. 1

CPWalker robotic platform (exoskeleton to guide the patients’ lower limbs and walker with PBWS to provide balance control during over-ground walking). The wide variety of operating modes comprehends from “robot in charge” to “patient in charge” states: i) position control mode; ii) high impedance control mode; iii) medium impedance control mode; iv) low impedance control mode; v) zero-force control mode

Fig. 2

Robot-based training program overview. First phase: sessions S1 to S8 for strength exercises where motor control was primary trained. Second phase: sessions S9 to S16 for power training where the assistance was progressively decreased with the patient’s progression. The improvements were assessed at three stages of analysis: before treatment begins, between both phases and at the end of the program (gray ellipses in the figure)

Fig. 3

First phase: strength training progression values along first 8 sessions of the robot-based therapy. Trajectory tracking motion was imposed by the robot. The light-gray line represents the movement amplitude (%ROM), the blue line the changes of %PBWS and the dark-gray line is referred to gait velocity percentage for each session

Fig. 4

Second phase: power training progression values along sessions 9 to 16 of the robot-based therapy. Six different levels of assistance were selected on the exoskeleton (combining hips and knees). The light-gray line represents the movement amplitude (%ROM), the blue line the changes of %PBWS and the dark-gray line is referred to gait velocity percentage for each session

Fig. 5

Levels of assistance (L1 to L6) depending on the patient (P1 to P4) and the AAN session (S9 to S16). The patients could jump to the next level if they achieved at least the 85% of the pattern desired for each session. The level for P4 in S11 is not represented because P4 lost this session

Fig. 6

a Results of GMFM-88 (D and E dimensions), b SCALE, c 6mwt, and d 10mwt in pre, middle and post analysis for all the patients (P1 to P4). The SCALE was measured bilaterally (left and right). The 10mwt was performed in two situations: comfortable speed (Comf) and maximum speed (Max)

Fig. 7

Maximum strength measures recorded for all the patients in pre (the light-pink line), middle (the dark-pink line) and post analysis (the purple line). Both legs were evaluated, right (R) and left (L)

Fig. 8

a GPS and b GDI for pre, middle and post kinematic analyzes of patients P1 to P4. The results represent means ± standard error bilaterally (left in red bars and right in green bars). Normality in GPS considers values lower than 7 points (doted-black line in (a)), and normality in GDI comprehends values higher than 100 points (doted-black line in (b))

Fig. 9

ROM performance measured walking some steps with CPWalker in two situations: a Session 3 for patient 1 (first phase of the training with trajectory tracking) and b Session 16 for patient 1 (second phase of the training through AAN strategies with level 5 of assistance (LI at hips and MI at knees))