Dynamic spasticity determines hamstring length and knee flexion angle during gait in children with spastic cerebral palsy.

Previous researchers reported that popliteal angle did not correlate well with knee angle during gait in individuals with spastic cerebral palsy (CP). To determine if hamstring spasticity, as measured by Modified Tardieu Scale (MTS) at rest, is associated with knee flexion angle at initial contact and midstance during gait. Thirty ambulatory children (mean age 8.7 ± 2.4 years) diagnosed with spastic CP participated. The hamstrings' spasticity was assessed in the supine position with the MTS, measuring R1 (muscle reaction to passive fast stretch), R2 (passive range of motion), and R2-R1 (dynamic component of spasticity). We conducted 3-dimensional computerized gait analysis and calculated semimembranosus muscle-tendon length and lengthening velocity during gait using musculoskeletal modeling and inverse kinematic analysis by OpenSim. Pearson correlation coefficients were calculated to estimate the association of MTS with biomechanical parameters during gait. Knee flexion angle at initial contact and maximal knee extension angle during stance phase significantly positively correlated with both R1 and ㅣR2 - R1ㅣ of MTS, but not with R2 angle. The length of semimembranosus at initial contact, end of swing, and minimal length during stance phase were strongly negatively associated with R1, rather than R2 or ㅣR2 - R1ㅣ angles. The R1 angle of MTS (muscle reaction to passive fast stretch) is more relevant correlate of knee flexion angle during gait than the R2 (passive range of motion).

Choi JY ，Park ES ，Park D ，Rha DW ... -  《-》

The relation between spasticity and muscle behavior during the swing phase of gait in children with cerebral palsy.

There is much debate about how spasticity contributes to the movement abnormalities seen in children with spastic cerebral palsy (CP). This study explored the relation between stretch reflex characteristics in passive muscles and markers of spasticity during gait. Twenty-four children with CP underwent 3D gait analysis at three walking velocity conditions (self-selected, faster and fastest). The gastrocnemius (GAS) and medial hamstrings (MEHs) were assessed at rest using an instrumented spasticity assessment that determined the stretch-reflex threshold, expressed in terms of muscle lengthening velocity. Muscle activation was quantified with root mean square electromyography (RMS-EMG) during passive muscle stretch and during the muscle lengthening periods in the swing phase of gait. Parameters from passive stretch were compared to those from gait analysis. In about half the children, GAS peak muscle lengthening velocity during the swing phase of gait did not exceed its stretch reflex threshold. In contrast, in the MEHs the threshold was always exceeded. In the GAS, stretch reflex thresholds were positively correlated to peak muscle lengthening velocity during the swing phase of gait at the faster (r = 0.46) and fastest (r = 0.54) walking conditions. In the MEHs, a similar relation was found, but only at the faster walking condition (r = 0.43). RMS-EMG during passive stretch showed moderate correlations to RMS-EMG during the swing phase of gait in the GAS (r = 0.46-0.56) and good correlations in the MEHs (r = 0.69-0.77) at all walking conditions. RMS-EMG during passive stretch showed no correlations to peak muscle lengthening velocity during gait. We conclude that a reduced stretch reflex threshold in the GAS and MEHs constrains peak muscle lengthening velocity during gait in children with CP. With increasing walking velocity, this constraint is more marked in the GAS, but not in the MEHs. Hyper-activation of stretch reflexes during passive stretch is related to muscle activation during the swing phase of gait, but has a limited contribution to reduced muscle lengthening velocity during swing. Larger studies are required to confirm these results, and to investigate the contribution of other impairments such as passive stiffness and weakness to reduced muscle lengthening velocity during the swing phase of gait.

Bar-On L ，Molenaers G ，Aertbeliën E ，Monari D ，Feys H ，Desloovere K ... -  《-》

Ankle and knee coupling in patients with spastic diplegia: effects of gastrocnemius-soleus lengthening.

Baddar A ，Granata K ，Damiano DL ，Carmines DV ，Blanco JS ，Abel MF ... -  《JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME》

Biomechanical and clinical correlates of swing-phase knee flexion in individuals with spastic cerebral palsy who walk with flexed-knee gait.

To identify clinical and biomechanical parameters that influence swing-phase knee flexion and contribute to stiff-knee gait in individuals with spastic cerebral palsy (CP) and flexed-knee gait. Retrospective analysis of clinical data and gait kinematics collected from 2010 to 2013. Motion and gait analysis laboratory at a children's hospital. Individuals with spastic CP (N=34; 20 boys, 14 girls; mean age ± SD, 10.1±4.1y [range, 5-20y]; Gross Motor Function Classification System I-III) who walked with flexed-knee gait ≥20° at initial contact and had no prior surgery were included; the more-involved limb was analyzed. Not applicable. The magnitude and timing of peak knee flexion (PKF) during swing were analyzed with respect to clinical data, including passive range of motion and Selective Control Assessment of the Lower Extremity, and biomechanical data, including joint kinematics and hamstring, rectus femoris, and gastrocnemius muscle-tendon length during gait. Data from participants demonstrated that achieving a higher magnitude of PKF during swing correlated with a higher maximum knee flexion velocity in swing (ρ=.582, P<0.001) and a longer maximum length of the rectus femoris (ρ=.491, P=.003). In contrast, attaining earlier timing of PKF during swing correlated with a higher knee flexion velocity at toe-off (ρ=-.576, P<.001), a longer maximum length of the gastrocnemius (ρ=-.355, P=.039), and a greater peak knee extension during single-limb support phase (ρ=-.354, P=.040). Results indicate that the magnitude and timing of PKF during swing were independent, and their biomechanical correlates differed, suggesting important treatment implications for both stiff-knee and flexed-knee gait.

Rha DW ，Cahill-Rowley K ，Young J ，Torburn L ，Stephenson K ，Rose J ... -  《-》

Relationship of spasticity to knee angular velocity and motion during gait in cerebral palsy.

Damiano DL ，Laws E ，Carmines DV ，Abel MF ... -  《GAIT & POSTURE》