Cerebral palsy affects movement and posture, resulting in a limited activity that is attributed to non-progressive disturbances occurring in the fetal or infant brain [1]. Since robot-assisted gait training (RAGT) induces changes in the brain plasticity, it appears promising in improving gross motor control of CP children with cerebral palsy [2-4].It could be hypothesized that RAGT can affect impaired selective voluntary motor control (SVMC), which is the inability to activate muscles to achieve a voluntary posture or movement [5]. Therefore, this pilot study investigated the efficacy of RAGT as monotherapy on lower limb SVMC, joint range of motion (ROM), walking ability, and gross motor measures.

The study received ethics committee approval from participating institutions. All parents and children provided written informed consent for participation. Twelve children [mean (SD) age, 10.9 (3.3) year; 2 girls] were tested at the baseline, after four weeks of intervention, and at 3-month follow-up. Children with spastic diparesis with toe-walking and/or scissoring patterns aged between 5-17 years were recruited. Only children who could attend the 4-week RAGT program regularly were enrolled. Children were excluded if they had used any muscle relaxants within the previous 6 months or had orthopedic surgery within the last year [2-4].

Standardized, validated questionnaires and evaluations [5-8] were used: goniometry, Selective Control Assessment of Lower Limbs Evaluation (SCALE), D and E parts of Gross Motor Function Measurement (GMFM), 10-meter walk test (10MWT) and 6-minute walk test (6MWT). During walking tests, all children wore footwear and orthoses, if regularly used. For SCALE, children performed isolated movements of the hip, knee, ankle, subtalar, and toe joints. Scores were assigned as: normal - joints moved selectively within at least 50% of the possible ROM, and at a physiological cadence; impaired - movement performed slower below 50% of ROM, with mirror and/or synergistic movements; or unable - no joint movement performed or synergy patterns present. Pre-post intervention goniometry and SCALE evaluations showed bilateral asymmetries in lower limbs across all children. Asymmetries were recorded as ‘more impaired limb (MIL)’ and ‘less impaired limb (LIL)’.

The Lokomat Pro device (Hocoma AG, Volketswil, Switzerland) was used [9]. Children attended 20 sessions scheduled on 20 consecutive working days. Therapy ranged 30-45 minutes and progressively increased by at least 3 minutes every other day [mean (SD), 39 (6) minute]. Walking speed [mean (SD), 1.4 (2.38) km/h] was set individually. The walking distance [mean (SD), 969 (172) meter] was gradually increased every other day by at least 50 meters. All children had an initial level of 50% body-weight support [mean (SD), 14.8 (4.76) kg], which was gradually decreased every other day for each child until the knee did not start to collapse into flexion during the stance phase.

Data were analyzed in MatLab (Mathworks Inc., USA). Shapiro-Wilk test (0.05 significance level) showed abnormal data distribution. The Wilcoxon sign rank test was used for the LIL and MIL, separately [10]. Spearman correlations were calculated for the following: goniometry/SCALE, GMFM D, E/10MWT, and GMFM D, E/6MWT.

Hip joint flexion contractures decreased bilaterally by 10° (P=0.004). Internal hip rotations decreased by 10° in LIL and 15° in MIL (P=0.002). Ankle dorsiflexion improved bilaterally by 10° (P=0.001). SCALE scores increased by 1.5 in LIL and 2.5 points in MIL (P=0.001). The 6MWT walking distance increased by 75 meters (P=0.001). 10MWT showed no significant change (P=0.89). GMFM-D improved by 8% (P<0.001) and GMFM-E by 6% (P=0.002). Correlations were found only between GMFM D, E scores and walking tests (rho=-0.614-0.784;P<0.05). Increased GMFM scores corre-lated with decreased time in 10MWT, and increased walking distance in 6MWT. There was no significant difference in short-term and 3-month follow-up data (P>0.05) across all measures.

Since active training seems to be more effective than passive training for motor learning and cortical reorganization in central motor impairments [2-4,9], RAGT likely improved motor control of CP children due to active training performed with a high-repetition-rate of guided movements in the most neutral pelvis and lower limbs position. To the best of our knowledge, this is the first study suggesting that RAGT improves SVMC and decreases hip joint internal rotation contractures. We support the previous results that CP children increased walking distance following RAGT [2-4]. It has been shown that the combination of RAGT and physiotherapy improves GMFM D,E scores [2-4].

Our outcomes suggest that although expensive (~300,000 Euro), RAGT, which is primarily used in rehabilitation centers, can improve D, E scores even when used as a stand-alone therapy. Although this study provides a foundation on which future studies can be built on, RAGT should be investigated over longer periods in different populations to further determine its effectiveness.

Ethical Approval: (i) Charles University, Prague, the Czech　Republic　(number 120/2015) dated August 12, 2015, and (ii) University Rehabilitation　Institute, Ljubljana, the Republic of Slovenia on October 5, 2015.

Contributors: DZ: conducted the research, drafted the work, revising and writing final approval of the version to be published; DZ, JJT, MS, PK, SV, KG-S, DR: substantial contri-butions to the conception or design of the work; the acquisition, analysis, and interpretation of data for the work; revising the work critically for important intellectual content; final approval of the version to be published; agreement with all co-authors to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Funding: Supported by a grant entitled ‘Project FTVS SVV 2017-2019-260346’ from Charles University in Prague, Czech Republic. This study was written within the program of the institutional support for science at Charles University Progress, No. Q41, Biological aspects of the investigation of human movement. Slovenian Research Agency (research core funding P2-0228);

Competing interests: None stated.

1. Jeevanantham D. Application of the international classification of functioning, disability and health - children and youth in children with cerebral palsy. Indian Pediatr. 2016; 53:805-10.

2. Borggraeffe I, Schemer JS, Klaiber M, Dabrowski E, Ammann-Reiffer C, Knecht B, et al. Robotic-assisted treadmill therapy improves walking and standing performance in children and adolescents with cerebral palsy. Eur J Paediatr Neurol. 2010;14:496-502.

3. Hilderley AJ, Fehlings D, Lee GW, Wright FV. Comparison of a robotic-assisted gait training program with a program of functional gait training for children with cerebral palsy: design and methods of a two group randomized controlled cross-over trial. Springer Plus. 2016;5:1886.

4. Vrecar I, Majdic N, Jemec I, Damjan H. Changes in passive range of motion of joints of the lower limbs in children with cerebral palsy after an intense training program on the Lokomat. Rehabilitacija. 2013;12:38-45.

5. Fowler EG, Staudt LA, Greenberg MB, Oppenheim WL. Selective Control Assessment of the Lower Extremity (SCALE): Development, validation, and interrater reliability of a clinical tool for patients with cerebral palsy. Dev Med Child Neurol. 2009;51:607-14.

6. Janda V, Pavlu D. Goniometrie. Brno: Institut pro dalsi vzdelavani pracovniku ve zdravotnictvi; 1993.

7. Alotaibi M, Long T, Kennedy E, Bavishi S. The efficacy of GMFM-88 and GMFM-66 to detect changes in gross motor function in children with cerebral palsy (CP): A literature review. Disabil Rehabil. 2014;36:617-27.

8. Thompson P, Beath T, Bell J. Test-retest reliability of the 10-metre fast walk test and 6-minute walk test in ambulatory school-aged children with cerebral palsy. Dev Med Child Neurol. 2008;50:370-6.

9. Columbo G, Joerg M, Schreier R, Dietz V. Treadmill training of paraplegic patients using a robotic orthosis. J Rehabil Res Dev. 2000;37:693-700.