Muscle morphology and architecture of the medial gastrocnemius between typically developing children with different ancestral background.

Muscle ultrasonography is frequently used to improve the understanding of musculoskeletal impairments in children with spastic cerebral palsy (SCP). So far, most studies on muscle morphology and architecture have included typically developing children and children with SCP with similar ancestry, being mainly Caucasian. Less is known about differences in muscle morphology between children with different ancestral backgrounds. Therefore, the aim of this study was to compare muscle morphology and architecture of the medial gastrocnemius in typically developing children with African, South Asian and Southeast Asian descent from Suriname. This explorative cohort study identified children as Maroon (Ghana, African descent), Hindustani (India, South Asian) or Javanese (Indonesia, Southeast Asian), aged 5-10 years. Using 3D freehand ultrasound with the subject prone, the following medial gastrocnemius parameters were defined: muscle tendon unit (MTU) length, muscle belly length, tendon length, muscle volume, muscle thickness, anatomical cross-sectional area (ACSA), fascicle length, pennation angle, and physiological cross-sectional area (PCSA). In addition, differences between ancestral groups were assessed for the length of the MTU, muscle, tendon and fascicles in two passive stretch conditions corresponding to an externally applied joint torque of 1Nm and 4Nm. One-way ANOVA with post hoc t-tests were used to investigate differences between the ancestral groups. In total, 100 Hindustani (n = 34), Javanese (n = 34) and Maroon (n = 32) children were included. For statistical analyses, we matched the children by age, which resulted in groups of 25 children per ancestral group (n = 75). There were no differences found in MTU length, muscle belly length, ACSA, PCSA and muscle volume. Tendon length, fascicle length and pennation angle were different between ancestral groups. Compared to Javanese children, tendon length was longer (p = 0.001) and pennation angle (p = 0.001) was larger in Maroon children and fascicle length was shorter in both Maroon and Hindustani children (p < 0.001). While there was a difference found in MTU length at different conditions of passive stretch between ancestries, no differences were found in the muscle, tendon and fascicles. This is the first study that investigated macroscopic morphological and architectural parameters for the medial gastrocnemius in one extended cohort of typically developing children, stratified in three ancestral subgroups. The current results imply that ancestry-specific reference data for children are needed, especially for tendon length, fascicle length and pennation angle when investigating altered muscle morphology in neurological or neuromuscular pathologies, such as SCP. Future studies should report the ancestral background when describing muscle morphology and architecture of children and ancestral specifications should be included in normative databases.

Reliability of 3D freehand ultrasound to assess lower limb muscles in children with spastic cerebral palsy and typical development.

This study investigated the reliability of 3-dimensional freehand ultrasound (3DfUS) to quantify the size (muscle volume [MV] and anatomical cross-sectional area [aCSA]), length (muscle length [ML], tendon length [TL], and muscle tendon unit length [MTUL]), and echo-intensity (EI, whole muscle and 50% aCSA), of lower limb muscles in children with spastic cerebral palsy (SCP) and typical development (TD). In total, 13 children with SCP (median age 14.3 (7.3) years) and 13 TD children (median age 11.1 (1.7) years) participated. 3DfUS scans of rectus femoris, semitendinosus, medial gastrocnemius, and tibialis anterior were performed by two raters in two sessions. The intra- and inter-rater and intra- and inter-session reliability were defined with relative and absolute reliability measures, that is, intra-class correlation coefficients (ICCs) and absolute and relative standard error of measurement (SEM and SEM%), respectively. Over all conditions, ICCs for muscle size measures ranged from 0.818 to 0.999 with SEM%s of 12.6%-1.6%. For EI measures, ICCs varied from 0.233 to 0.967 with SEM%s of 15.6%-1.7%. Length measure ICCs ranged from 0.642 to 0.999 with SEM%s of 16.0%-0.5%. In general, reliability did not differ between the TD and SCP cohort but the influence of different muscles, raters, and sessions was not constant for all 3DfUS parameters. Muscle length and muscle tendon unit length were the most reliable length parameters in all conditions. MV and aCSA showed comparable SEM%s over all muscles, where tibialis anterior MV was most reliable. EI had low-relative reliability, but absolute reliability was better, with better reliability for the distal muscles in comparison to the proximal muscles. Combining these results with earlier studies describing muscle morphology assessed in children with SCP, 3DfUS seems sufficiently reliable to determine differences between cohorts and functional levels. The applicability on an individual level, for longitudinal follow-up and after interventions is dependent on the investigated muscle and parameter. Moreover, the semitendinosus, the acquisition, and processing of multiple sweeps, and the definition of EI and TL require further investigation. In general, it is recommended, especially for longitudinal follow-up studies, to keep the rater the same, while standardizing acquisition settings and positioning of the subject.

Interventions and lower-limb macroscopic muscle morphology in children with spastic cerebral palsy: a scoping review.

AIM: To identify and map studies that have assessed the effect of interventions on lower-limb macroscopic muscle-tendon morphology in children with spastic cerebral palsy (CP). METHOD: We conducted a literature search of studies that included pre- and post-treatment measurements of lower-limb macroscopic muscle-tendon morphology in children with spastic CP. Study quality was evaluated and significant intervention effects and effect sizes were extracted. RESULTS: Twenty-eight articles were identified. They covered seven different interventions including stretching, botulinum neurotoxin A (BoNT-A), strengthening, electrical stimulation, whole-body vibration, balance training, and orthopaedic surgery. Study quality ranged from poor (14 out of 28 studies) to good (2 out of 28). Study samples were small (n=4-32) and studies were variable regarding which muscles and macroscopic morphological parameters were assessed. Inconsistent effects after intervention (thickness and cross-sectional area for strengthening, volume for BoNT-A), no effect (belly length for stretching), and small effect sizes were reported. INTERPRETATION: Intervention studies reporting macroscopic muscle-tendon remodelling after interventions are limited and heterogeneous, making it difficult to generalize results. Studies that include control groups and standardized assessment protocols are needed to improve study quality and data synthesis. Lack or inconclusive effects at the macroscopic level could indicate that the effects of interventions should also be evaluated at the microscopic level. WHAT THIS PAPER ADDS: Muscle-targeted interventions to remodel muscle morphology are not well understood. Studies reporting macroscopic muscle remodelling following interventions are limited and heterogeneous. Passive stretching may preserve but does not increase muscle length. The effects of isolated botulinum neurotoxin A injections on muscle volume are inconsistent. Isolated strengthening shows no consistent increase in muscle volume or thickness.

Semi-automatic methods for tracking the medial gastrocnemius muscle-tendon junction using ultrasound: a validation study.

NEW FINDINGS: What is the central question of this study? Is the proposed semi-automatic algorithm suitable for tracking the medial gastrocnemius muscle-tendon junction in ultrasound images collected during passive and active conditions? What is the main finding and its importance? The validation of a method allowing efficient tracking of the muscle-tendon junction in both passive and active conditions, in healthy as well as in pathological conditions. This method was tested in common acquisition conditions and the developed software made freely available. ABSTRACT: Clinically relevant information can be extracted from ultrasound (US) images by tracking the displacement of the junction between muscle and tendon. This paper validated automatic methods for tracking the location of muscle-tendon junction (MTJ) between the medial gastrocnemius and the Achilles tendon during passive slow and fast stretches, and active ankle rotations while walking on a treadmill. First, an automatic algorithm based on an optical flow approach was applied on collected US images. Second, results of the automatic algorithm were evaluated and corrected using a quality measure that indicated which critical images need to be manually corrected. US images from 12 typically developed (TD) children, 12 children with spastic cerebral palsy (SCP) and eight healthy adults were analysed. Automatic and semi-automatic tracking methods were compared to manual tracking using root mean square errors (RMSE). For the automatic tracking, RMSE was less than 3.1 mm for the slow stretch and 5.2 mm for the fast stretch, the worst case being for SCP. The tracking results in the fast stretch condition were improved (especially in SCP) by using the semi-automatic approach, with an RMSE reduction of about 30%. During walking, the semi-automatic method also reduced errors, with a final RMSE of 3.6 mm. In all cases, data processing was considerably shorter using the semi-automatic method (2 min) compared to manual tracking (20 min). A quick manual correction considerably improves tracking of the MTJ during gait and allows to achieve results suitable for further analyses. The proposed algorithm is freely available.

Tone Reduction and Physical Therapy: Strengthening Partners in Treatment of Children with Spastic Cerebral Palsy.

The aim of this paper is to provide a clinically applicable overview of different tone reducing modalities and how these can interact with or augment concurrent physical therapy (PT). Botulinum toxin (BoNT), oral tone-regulating medication, intrathecal baclofen (ITB), and selective dorsal rhizotomy are discussed within a physiotherapeutic context and in view of current scientific evidence. We propose clinical reasoning strategies to identify treatment goals as well as the appropriate and corresponding treatment interventions. Instrumented measurement of spasticity, standardized clinical assessment, and 3D clinical motion analysis are scientifically sound tools to help select the appropriate treatment and, when needed, to selectively target or spare individual muscles. In addition, particular attention is given to strength training as a necessary tool to tackle muscle weakness associated with specific modalities of tone reduction. More research is needed to methodologically assess the long-term effectiveness of such individualized tone treatment, optimize parameters such as medication dosage, and gain more insight into the kind of PT techniques that are essential in conjunction with tone reduction.

Medial gastrocnemius volume and echo-intensity after botulinum neurotoxin A interventions in children with spastic cerebral palsy.

AIM: This cross-sectional investigation evaluated whether recurrent botulinum neurotoxin A (BoNT-A) interventions to the medial gastrocnemius have an influence on muscle morphology, beyond Gross Motor Function Classification System (GMFCS) level. METHOD: A cohort of typically developing children (n=67; 43 males, 24 females; median age 9y 11mo [range 7y 10mo-11y 6mo]), a cohort of children with spastic cerebral palsy (CP) naive to BoNT-A interventions (No-BoNT-A; n=19; 10 males, nine females; median age 9y 3mo [range 8y 5mo-10y 10mo]) and a cohort of children with spastic CP with a minimum of three recurrent BoNT-A interventions to the medial gastrocnemius (BoNT-A; n=19; 13 males, six females; median age 9y 8mo [range 7y 3mo-10y 7mo]) were recruited. Three-dimensional freehand ultrasound was used to estimate medial gastrocnemius volume normalized to body mass and echo-intensity. RESULTS: Normalized medial gastrocnemius volume and echo-intensity significantly differed between the two spastic CP cohorts (p≤0.05), with the BoNT-A cohort having larger alterations. Associations between normalized medial gastrocnemius volume and echo-intensity were highest in the No-BoNT-A cohort, followed by the BoNT-A cohort. Multiple regression analyses revealed that both GMFCS level and BoNT-A intervention history were significantly associated with smaller normalized medial gastrocnemius volume and higher echo-intensity. INTERPRETATION: Recurrent BoNT-A interventions may induce alterations to medial gastrocnemius volume and echo-intensity beyond the natural history of the spastic CP pathology. WHAT THIS PAPER ADDS: In spastic cerebral palsy, medial gastrocnemius volumes are smaller and echo-intensities higher compared with typical development. Alterations after botulinum neurotoxin A intervention (BoNT-A) are larger than in no BoNT-A intervention. Gross Motor Function Classification System level and BoNT-A history significantly associate with medial gastrocnemius and echo-intensity alterations.

VOLUMEN DEL MÚSCULO GASTROCNEMIUS MEDIAL E INTENSIDAD DE LA ECOGRAFÍA DESPUÉS DE LA COLOCACIÓN DE NEUROTOXINA BOTULÍNICA (TIPO A), EN NIÑOS CON PARÁLISIS CEREBRAL ESPÁSTICA (PC): OBJETIVO: Esta investigación de corte transversal evaluó si la colocación recurrente de neurotoxina botulínica tipo A (BoNT-A) en el músculo gastrocnemius medial tienen una influencia en la morfología muscular, más allá del nivel del Sistema de Clasificación de la Función Motora Gruesa (GMFCS, siglas en ingles). MÉTODO: Una cohorte de niños con desarrollo tipico (n = 67; 43 varones, 24 mujeres; mediana de edad 9 años 11 meses [rango 7 años 10 meses -11 años 6 meses]), otra cohorte de niños con parálisis cerebral espástica (PC) que no habían recibido intervenciones de BoNT-A ( n = 19; 10 hombres, nueve mujeres; mediana de edad 9 años 3 meses [rango 8 años 5 meses -10 años 10 meses]) y una cohorte de niños con PC espástica con un mínimo de tres administraciones recurrentes de BoNT-A en el músculo gastrocnemius medial (BoNT-A; n = 19; 13 varones, seis mujeres; mediana de edad 9 años 8 meses [rango 7 años 3 meses - 10 años 7 meses]) fueron reclutados. Se usó ultrasonido tridimensional a mano alzada para estimar el volumen del músculo gastrocnemius medial normalizado a la masa corporal y la intensidad del eco. RESULTADOS: El volumen del músculo gastrocnemius medial normalizado y la intensidad del eco difirieron significativamente entre las dos cohortes de PC espástica (p≤0,05), la cohorte BoNT-A tuvo alteraciones mayores. Las asociaciones entre el volumen músculo gastrocnemius medial normalizado y la intensidad del eco fueron más altas en la cohorte No-BoNT-A, seguidas de la cohorte BoNT-A. Los análisis de regresión múltiple revelaron que tanto el nivel de GMFCS como el antecedente de intervención de BoNT-A se asociaron significativamente con un volumen del músculo gastrocnemius medial normalizado más pequeño y una mayor intensidad de eco. INTERPRETACIÓN: La colocación recurrentes de BoNT-A pueden inducir alteraciones en el volumen del músculo gastrocnemius medial y en la intensidad del eco más allá de la historia natural de la patología por PC espástica.

VOLUME E ECO-INTENSIDADE DO MÚSCULO GASTROCNÊMIO MEDIAL APÓS INTERVENÇÕES COM NEUROTOXINA BOTULÍNICA A EM CRIANÇAS COM PARALISIA CEREBRAL ESPÁSTICA: OBJETIVO: Esta investigação transversal avaliou se intervenções recorrentes com neurotoxina botulínica A (NTBo-A) no músculo gastrocnêmio medial têm influência na morfologia muscular, além do nível segundo o Sistema de Classificação da Função Motora Grossa (GMFCS). MÉTODO: Uma coorte de crianças com desenvolvimento típico (n=67; 43 do sexo masculino, 24 do sexo feminino; idade mediana 9a 11m [variação 7a 10m-11a 6m]), uma coorte de crianças com paralisia cerebral espástica (PC) que nunca recebeu intervenções com NTBo-A (No-NTBo-A; n=19; 10 do sexo masculino, nove do sexo feminino; idade mediana 9a 3m [variação 8a 5m-10a 10m]) e uma coorte de crianças com PC espástica com no mínimo três intervenções de NTBo-A no músculo gastrocnêmio medial (NTBo-A; n=19; 13 do sexo mascuino, seis do sexo feminino; idade mediana 9a 8m [variação 7a 3m-10a 7m]) foram recrutadas. Ultrassom tridimensional foi usado para estimar o volume do gastrocnêmio normalizado para a massa corporal e eco-intensidade. RESULTADOS: O volume normalizado e eco-intensidade do músculo gastrocnêmio medial diferiu significantemente entre as duas coortes de PC espástica (p≤0,05), com a coorte NTBo-A tendo maiores alteracões. Associações entre o volume normalizado do gastrocnêmio e eco-intensidade foram maiores na coorte No-NTBo-A, seguida pela coorte NTBo-A. Análises de regressão múltipla revelaram que tanto o nível GMFCS quanto a história de intervenção com NTBo-A foram significativamente associadas com menor volume normalizado do músculo gastrocnêmio medial e maior eco-intensidade. INTERPRETAÇÃO: Intervenções recorrentes com NTBo-A podem induzir alterações no volume e eco-intensidade do músculo gastrocnêmio medial, além da história natural da patologia da PC espástica.

Rectus femoris transfer improves stiff knee gait in hemiplegic adults following stroke or traumatic brain injury.

The aim of this study was to provide quantitative evidence of the effect of rectus femoris (RF) transfer surgery on improving gait in adults suffering from stiff knee gait (SKG) following stroke or traumatic brain injury (TBI). Retrospective cohort study University hospital, department of orthopaedic surgery Hemiplegic patients with decreased peak knee flexion in swing, reduced total knee range of motion and spasticity of the RF demonstrated by a positive Duncan Ely test and a pathologic dynamic electromyography of the RF. Ten right hemiplegic patients had a distal RF transfer. Pre- and postoperative kinematic, kinetic, and spatiotemporal parameters derived from 3D gait analysis and parameters from clinical examinations were retrospectively compared. All patients (average age 40 ± 29 years) had an improvement of their gait. Statistically significant improvements were observed in walking velocity and peak knee flexion in swing (19.93° ±11.80°), knee flexion velocity at toe-off (110.26° ± 65.74°) and total knee range of motion (20.78° ± 0.66°). RF transfer improves knee flexion in swing in adult patients suffering from SKG following stroke or TBI and is thus a reliable treatment option.

Medial gastrocnemius muscle stiffness cannot explain the increased ankle joint range of motion following passive stretching in children with cerebral palsy.

NEW FINDINGS: What is the central question of this study? Can the increased range of motion seen acutely after stretching in children with cerebral palsy be explained by changes in the stiffness of the medial gastrocnemius fascicles? What is the main finding and its importance? We show, for the first time, that passive muscle and tendon properties are not changed acutely after a single bout of stretching in children with cerebral palsy and, therefore, do not contribute to the increase in range of motion. This contradicts common belief and what happens in healthy adults. ABSTRACT: Stretching is often used to increase or maintain the joint range of motion (ROM) in children with cerebral palsy (CP), but the effectiveness of these interventions is limited. Therefore, our aim was to determine the acute changes in muscle-tendon lengthening properties that contribute to increased ROM after a bout of stretching in children with CP. Eleven children with spastic CP [age 12.1 (3 SD) years, 5/6 hemiplegia/diplegia, 7/4 gross motor function classification system level I/II] participated. Each child received three sets of five × 20 s passive, manual static dorsiflexion stretches separated by 30 s rest, with 60 s rest between sets. Before and immediately after stretching, ultrasound was used to measure medial gastrocnemius fascicle lengthening continuously over the full ROM and an individual common ROM pre- to post-stretching. Simultaneously, three-dimensional motion of two marker clusters on the shank and the foot was captured to calculate ankle angle, and ankle joint torque was calculated from manually applied torques and forces on a six degrees-of-freedom load cell. After stretching, the ROM was increased [by 9.9 (12.0) deg, P = 0.005]. Over a ROM common to both pre- and post-measurements, there were no changes in fascicle lengthening or torque. The maximal ankle joint torque tolerated by the participants increased [by 2.9 (2.4) N m, P = 0.003], and at this highest passive torque the maximal fascicle length was 2.8 (2.4) mm greater (P = 0.009) when compared with before stretching. These results indicate that the stiffness of the muscle fascicles in children with CP remains unaltered by an acute bout of stretching.

Muscle and tendon lengthening behaviour of the medial gastrocnemius during ankle joint rotation in children with cerebral palsy.

NEW FINDINGS: What is the central question of this study? Which structures of the medial gastrocnemius muscle-tendon unit contribute to its lengthening during joint rotation and thus receive the stretching stimulus? What is the main finding and its importance? We show, for the first time, that muscle and tendon lengthen in a different manner in children with cerebral palsy compared with typically developing children during a similar amount of muscle-tendon unit lengthening or joint rotation. This indicates possible differences in mechanical muscle and tendon properties attributable to cerebral palsy, which are not evident by assessment of muscle function at the level of a joint. ABSTRACT: Children with cerebral palsy (CP) commonly present with reduced ankle range of motion (ROM) attributable, in part, to changes in mechanical properties of the muscle-tendon unit (MTU). Detailed information about how muscle and tendon interact to contribute to joint rotation is currently lacking but might provide essential information to explain the limited effectiveness of stretching interventions in children with CP. The purpose of this study was to quantify which structures contribute to MTU lengthening and thus receive the stretch during passive ankle joint rotation. Fifteen children with CP (age, in mean ± SD, 11.4 ± 3 years) and 16 typically developing (TD) children (age, in mean ± SD, 10.2 ± 3 years) participated. Ultrasound was combined with motion tracking, joint torque and EMG to record fascicle, muscle and tendon lengthening of the medial gastrocnemius during passive ankle joint rotations over the full ROM and a common ROM. In children with CP, relative to MTU lengthening, muscle and fascicles lengthened less (CP, 50.4% of MTU lengthening; TD, 63% of MTU lengthening; P < 0.04) and tendon lengthened more (CP, 49.6% of MTU lengthening; TD, 37% of MTU lengthening; P < 0.01) regardless of the ROM studied. Differences between groups in the amount of lengthening of the underlying structures during a similar amount of joint rotation and MTU displacement indicate possible differences in tissue mechanical properties attributable to CP, which are not evident by assessment at the level of a joint. These factors should be considered when assessing and treating muscle function in children with CP, for example during stretching exercises, because the muscle might not receive much of the applied lengthening stimulus.

Estimating medial gastrocnemius muscle volume in children with spastic cerebral palsy: a cross-sectional investigation.

AIM: This cross-sectional investigation evaluates the reliability of estimating medial gastrocnemius anatomical cross-sectional area (aCSA) in typically developing and spastic cerebral palsy (SCP) cohorts. It verifies whether muscle volume estimations based on aCSA improve when aCSA is multiplied by muscle-tendon unit (MTU) or muscle length, and whether the resulting errors in volume estimations are smaller than changes after intervention. METHOD: Fifteen typically developing children (mean age 8y 2mo [SD 1y 5mo], six males, nine females) and 30 children with SCP (mean age 9y 2mo [SD 2y 5mo], 22 males, eight females, Gross Motor Function Classification System [GMFCS] level I=15, II=15) participated in the investigation. The SCP cohort was divided according to GMFCS level. A three-dimensional freehand ultrasound technique was used to estimate medial gastrocnemius aCSA, muscle volume, MTU, and muscle length. Estimated muscle volume (aCSA×MTU or muscle length) was compared with the measured muscle volume. RESULTS: Anatomical cross-sectional area, muscle volume, and muscle length significantly differed between the typically developing and two SCP cohorts (p≤0.050). aCSA multiplied by either MTU or muscle length improved estimations of medial gastrocnemius volume. Leave-one-out cross-validation revealed an absolute difference with measured muscle volume of 3.77 ml (SD 2.90). INTERPRETATION: This investigation revealed that medial gastrocnemius muscle volume can be reliably estimated in a clinically feasible manner in typically developing children and those with SCP. WHAT THIS PAPER ADDS: Medial gastrocnemius anatomical cross-sectional area (aCSA) can be reliably estimated in children with spastic cerebral palsy. The location of the anatomical cross-section should be taken with respect to muscle and not bone length. Medial gastrocnemius volume can be reliably estimated by multiplying aCSA and muscle length. The errors in volume estimations are smaller than reported differences after interventions.