Typically, Spastic Paresis (SCP) causes morphological changes of m. gastrocnemius medialis (GM) that may change its mechanical characteristics. An enhanced resistance to dorsal flexion may in part be explained by such changes.@en

Due to their sensorimotor disorders, children with cerebral palsy (CP) typically experience poor balance control during standing and walking [1]. Virtual Reality (VR) is increasingly used in balance rehabilitation since literature has indicated some promising effects on for instance motivation [2] and functional outcomes [3] in several patient populations. Some preliminary studies have investigated the effect of VR training on balance in children with CP, however, they describe mixed results [4,5]. The contradictory findings could be the result of insufficient power due to small sample size and use of different measures of balance.@en

The process of clinical gait analysis interpretation is complex and subject to the experience and professional background of the gait analyst. Here we present a novel, systematic way of reasoning, to bridge the critical gap between identifying abnormal gait features and finding their underlying impairments [1], to be addressed by a therapeutic intervention. The method is illustrated using a clinical case of a 7yo girl M. with spastic diplegic cerebral palsy, GMFCS level II, due to periventricular leucomalacia associated with prematurity (26+2 weeks).@en

Gait Analysis (GA) allows the quantitative assessment of walking. Over the years, several descriptors have been developed with the aim to derive an overall GA assessment based on a synthetic score. Examples are the Gait Deviation Index (GDI) [1], and the Movement Analysis Profile (MAP) [2]. These indices are useful to assess the overall quality of gait patterns, but inherently do not provide information about the nature of the deviation (offset, scaling, time shift) or about the direction of the deviation (too much flexion or extension). It was observed that certain gait abnormalities corresponded to specific deviations in kinematic angles [3]. E.g. crouch gait is characterized by a persistent knee flexion that can be observed as a shift in the baseline of the knee flexion/extension angle.@en

Selective dorsal rhizotomy (SDR) is a neurosurgical treatment to reduce spasticity in children with cerebral palsy (CP). Where some children show large improvements on domains of motor function and mobility, others do not [1–3]. Since SDR is a highly invasive and irreversible treatment, it is important to select only those candidates who are most likely to benefit from the procedure.@en

Spasticity as part of a central neurological disorder is characterized by a ‘velocity dependent hyperactive stretch-reflex’ [1]. Secondary, morphological adaptations of the muscle-tendon complex reduce the passive joint angle-moment relationship (i.e. passive ROM) [2]. Potentially, joint hyper-resistance, as a result of either the neurological disorder, muscle morphology or both, can be clinically assessed [3]. Botulinum Toxin-A (BoNT-A), in combination with casting and physiotherapy are regularly used as conservative treatment in children with a spastic paresis to improve gait. While in some studies improvements resulting from this approach are reported, large treatment response variability persists [4]. Heterogeneity in treatment effectiveness may be due to a clinical focus at the joint impairment level rather than on the contributing mechanisms of joint hyper-resistance. In recent years great advances have been made in standardized, objective assessments of stretch reflexed induced joint hyper resistance [5]. 3D ultrasound (3DUS), allows morphometry of the muscle-tendon complex in children with spastic paresis [6]. The combination of instrumented assessments of neurological, muscle morphology and gait characteristics following treatment has not been carried out.@en

A common gait limitation in cerebral palsy (CP) is a reduced ability to generate power at the ankle during push off. This may be due a number of factors, such as muscle weakness or disrupted neuromuscular control. It has been shown that with the use real-time feedback, children with CP can improve key gait parameters such as knee and hip extension [1]. However, it is not known if children can improve ankle power, or, how they would achieve this change at the neuromuscular level. The use of synergy analysis to describe dynamic motor control (DMC) in CP is growing and has been shown to be predictive of treatment outcomes [2].@en

Spasticity, i.e. exaggerated velocity-dependent stretch reflex activity, is one of the key impairments in neurological diseases, but its effect on gait is unclear [1]. To quantify spastic reflexes during gait, ankle rotations have been applied by mechanical devices [2,3], but these are cumbersome and can affect gait. Recently, it has been shown that treadmill accelerations can be used to evoke stretch reflexes during gait in the calf muscles of healthy adults [4]. However, the applicability of this approach in children and in patients with neurological diseases has yet to be demonstrated.@en