The Non-Affected Muscle Volume Compensates for the Partial Loss of Strength after Injection of Botulinum Toxin A

Local botulinum toxin (BTX-A, Botox®) injection in overactive muscles is a standard treatment in patients with cerebral palsy. The effect is markedly reduced in children above the age of 6 to 7. One possible reason for this is the muscle volume affected by the drug. Nine patients (aged 11.5; 8.7–14.5 years) with cerebral palsy GMFCS I were treated with BTX-A for equinus gait at the gastrocnemii and soleus muscles. BTX-A was administered at one or two injection sites per muscle belly and with a maximum of 50 U per injection site. Physical examination, instrumented gait analysis, and musculoskeletal modelling were used to assess standard muscle parameters, kinematics, and kinetics during gait. Magnetic resonance imaging (MRI) was used to detect the affected muscle volume. All the measurements were carried out pre-, 6 weeks post-, and 12 weeks post-BTX-A. Between 9 and 15% of the muscle volume was affected by BTX-A. There was no effect on gait kinematics and kinetics after BTX-A injection, indicating that the overall kinetic demand placed on the plantar flexor muscles remained unchanged. BTX-A is an effective drug for inducing muscle weakness. However, in our patient cohort, the volume of the affected muscle section was limited, and the remaining non-affected parts were able to compensate for the weakened part of the muscle by taking over the kinetic demands associated with gait, thus not enabling a net functional effect in older children. We recommend distributing the drug over the whole muscle belly through multiple injection sites

Gait in hemiplegic cerebral palsy: effects of ankle foot orthoses

Cerebrale parese (CP) is een klinisch syndroom gekenmerkt door een persisterende houdings- of bewegingsstoornis ten gevolge van een niet-progressief pathologisch proces dat het centrale zenuwstelsel tijdens de ontwikkeling (voor, tijdens of kort na het tijdstip van de geboorte) heeft beschadigd. De symptomen kunnen variëren naarmate het kind ouder wordt. De typen bewegingsstoornissen kunnen onderverdeeld worden in topografische en neurologische stoornissen. Zo betreft spastische hemiparetische CP hoofdzakelijk één lichaamshelft, links of rechts. Dit proefschrift gaat voornamelijk over deze groep patiënten. Het lopen op de tenen met een voorvoetlanding van het aangedane been is de meest voorkomende afwijking in het looppatroon van kinderen met hemiparetische CP. Naast chirurgische, medicatieve en fysiotherapeutische behandelingsmethodes, worden enkel-voetorthesen (EVO s) ingezet om de tenengang te corrigeren. Tevens kunnen orthesen op het skelet een corrigerende werking uitoefenen of helpen om verkortingen van de kuitspieren tegen te gaan. Een EVO kan door haar biomechanische eigenschappen de positie van de voet ten opzichte van het onderbeen beheersen en een valvoet tijdens de zwaaifase van de gangcyclus verhinderen. Het doel van dit proefschrift is om het meest voorkomende looppatroon bij patiënten met een spastische hemiparetische CP, namelijk een tenengang met voorvoetlanding, te onderzoeken. Tevens werden de effecten van EVO s op dit looppatroon onderzocht. De onderzoeken die in dit proefschrift worden gepresenteerd dragen bij tot het behalen van deze doelstelling. De geïnstrumenteerde gangbeeld analyse en de analyse van oppervlakte electromyografische (EMG) signalen waren de onderzoeksmethodes die in alle onderzoeken werden gebruikt voor het verzamelen van de data. De belangrijkste conclusie die uit dit proefschrift getrokken kan worden is dat het tenenlopen bij patiënten met hemiparetische CP kan worden gerelateerd aan zowel primaire factoren, die door de aandoening zelf ontstaan, als aan secundaire (compenserende) factoren. Tevens werden niet alleen in het aangedane been maar ook in het niet aangedane been duidelijk hogere frequenties in de EMG registraties gevonden. Dit duidt erop dat beide lichaamshelften in het therapieplan van patiënten een rol moeten spelen. Alhoewel het looppatroon met een EVO verbeterde ten opzichte van blootsvoets lopen, kwam dit in de EMG registraties en de kinetica niet naar voren. Vooral het pathologische activiteitenpatroon van de m. gastrocnemius medialis en de m. rectus femoris en ook de verhoogde frequentie van de EMG signalen konden met een EVO niet beïnvloed worden.General introduction An electromyographic analysis of obligatory (hemiplegic cerebral palsy) and voluntary (normal) unilateral toe walking Comparison of a dynamic and a hinged ankle-foot orthosis by gait analysis in patients with hemiplegic cerebral palsy Changes in muscle activity in children with hemiplegic cerebral palsy while walking with and without ankle-foot orthoses Influence of an ankle foot orthosis on muscle activity during gait in children with hemiplegic cerebral palsy Changes in gait and EMG when walking with the Masai Barefoot Technique General discussion Summary Samenvatting (Dutch summary) Acknowledgements About the author and list of publicationsstatus: publishe

Immediate effects of unilateral restricted ankle motion on gait kinematics in healthy subjects

Correcting a pathological toe walking gait pattern can be achieved by restricting excessive plantarflexion during the swing phase of gait. A common conservative treatment measure is providing the patient with an ankle-foot-orthosis on the affected lower leg. This study examined the lower body gait kinematics and temporal-spatial parameters of fifteen healthy adults when walking freely and with unilateral restricted ankle motion. The latter was achieved by fitting an ankle-foot-orthosis. Specific hip and knee kinematic parameters and temporal-spatial parameters were investigated. Differences between the two conditions were calculated by paired Student's t-tests and 95% confidence intervals. Unilateral restricted ankle motion influenced kinematics mainly in the swing phase. Hip and knee peak flexion in the swing phase were increased on the restricted side (hip: 49.2° (SD 4.2°), knee: 75.9° (SD 6.1°)) compared to walking freely (hip: 43.3° (SD 4.5°), knee: 66.7° (SD 5.3°)). Peak hip flexion occurred earlier in the swing phase in the restricted condition (85% (SD 2%)) compared to the free-walking condition (96% (SD 5%)). For these parameters, the confidence intervals were different, indicating clinical relevance. Walking with unilateral restricted ankle motion had a negative effect on walking velocity, cadence, step time, and step length. The confidence intervals, however, overlapped. These results might be a reaction to unusual sensory feedback from the feet with the ankle-foot-orthosis or due to increased hip flexor activity compensating for the reduced function of the plantarflexors. The evaluation of the immediate changes in unilateral restricted ankle motion in individuals with healthy gaits can contribute to a more complete understanding on this topic

The effects of walking speed on upper body kinematics during gait in healthy subjects

Patients undergoing a clinical gait analysis often walk slower than healthy people. However, data on how speed affects upper body movements, especially of the arms and shoulders, are scarce. Therefore, in this descriptive study, we examined how changes in walking speed affect upper-body kinematics and aspects of intersegmental coordination between upper and lower body during overground walking in a group of healthy adult subjects. Three-dimensional gait data were collected on 20 healthy subjects (aged between 22 and 31 years) walking at six speeds ranging from extremely slow to very fast. Our results showed significant speed-related changes of upper body kinematic movement curves in three aspects, namely in amplitude (curves for shoulder flexion and abduction, elbow flexion, pelvic obliquity and rotation), timing (curves for shoulder extension and abduction, elbow extension, pelvic rotation) and curve pattern (curves for shoulder and elbow flexion, shoulder rotation, pelvic tilt). The intersegmental coordination between the thorax and pelvis and arm and leg was also affected by a change of walking speed. Our data supplement the already available data in the literature examining the effects of walking speed on lower extremity motion. Furthermore, the data can be used as a reference for both basic biomechanical and clinical gait studies. The results will help in clinical practice to differentiate between effects caused by walking speed and underlying pathology

The association between premature plantarflexor muscle activity, muscle strength, and equinus gait in patients with various pathologies

This study provides an overview on the association between premature plantarflexor muscle activity (PPF), muscle strength, and equinus gait in patients with various pathologies. The purpose was to evaluate whether muscular weakness and biomechanical alterations are aetiological factors for PPF during walking, independent of the underlying pathology. In a retrospective design, 716 patients from our clinical database with 46 different pathologies (orthopaedic and neurologic) were evaluated. Gait analysis data of the patients included kinematics, kinetics, electromyographic activity (EMG) data, and manual muscle strength testing. All patients were clustered three times. First, patients were grouped according to their primary pathology. Second, all patients were again clustered, this time according to their impaired joints. Third, groups of patients with normal EMG or PPF, and equinus or normal foot contact were formed to evaluate the association between PPF and equinus gait. The patient groups derived by the first two cluster methods were further subdivided into patients with normal or reduced muscle strength. Additionally, the phi correlation coefficient was calculated between PPF and equinus gait. Independent of the clustering, PPF was present in all patient groups. Weak patients revealed PPF more frequently. The correlations of PPF and equinus gait were lower than expected, due to patients with normal EMG during loading response and equinus. These patients, however, showed higher gastrocnemius activity prior to foot strike together with lower peak tibialis anterior muscle activity in loading response. Patients with PPF and a normal foot contact possibly apply the plantarflexion-knee extension couple during loading response. While increased gastrocnemius activity around foot strike seems essential for equinus gait, premature gastrocnemius activity does not necessarily produce an equinus gait. We conclude that premature gastrocnemius activity is strongly associated with muscle weakness. It helps to control the knee joint under load independent from the underlying disease, and it is therefore a secondary deviation. If treated as primary target, caution should be exercised

Upper body movements in children with hemiplegic cerebral palsy walking with and without an ankle-foot orthosis

It has previously been discussed that treatment of the hemiplegic arm in patients with cerebral palsy can improve gait parameters in the lower body. Our question was whether improving the ankle rocker with an orthosis has an effect on the upper body during walking. The main aim was to investigate, which trunk and arm kinematics of toe walking children with hemiplegic cerebral palsy are changed by wearing a hinged ankle-foot orthosis, restoring an initial heel contact.; Specific parameters of the pelvis, thorax, and arm kinematics were investigated. Differences in the hemiplegic side between the barefoot and the orthotic condition were calculated by Students t-tests. Additionally, the 95% confidence intervals were used to explore clinically relevant differences between the controls and the patients and asymmetries within the patients' affected and unaffected sides.; Pelvic tilt range of motion (barefoot: 7.5° (6.1-9.0°), orthosis: 6.6° (5.1-8.1) P=0.040) and mean shoulder abduction (barefoot: 14.3° (10.2-18.4°), orthosis: 12.1° (8.4-15.8) P=0.027) were the only two parameters with statistically significant differences, although not clinically relevant, between the barefoot and orthotic conditions. Abnormalities in all three planes were explored between the patients and controls. The entire trunk was more externally rotated, the pelvis stood lower, and the elbow was more flexed on the hemiplegic side compared to the unaffected side.; A hinged ankle-foot orthosis, restoring the first ankle rocker, had no clinically relevant effects on trunk kinematics. None of the observed upper body gait deviations seemed to be secondary to or caused by toe walking

The influence of muscle strength on the gait profile score (GPS) across different patients

BACKGROUND Muscle strength greatly influences gait kinematics. The question was whether this association is similar in different diseases. METHODS Data from instrumented gait analysis of 716 patients were retrospectively assessed. The effect of muscle strength on gait deviations, namely the gait profile score (GPS) was evaluated by means of generalised least square models. This was executed for seven different patient groups. The groups were formed according to the type of disease: orthopaedic/neurologic, uni-/bilateral affection, and flaccid/spastic muscles. RESULTS Muscle strength had a negative effect on GPS values, which did not significantly differ amongst the different patient groups. However, an offset of the GPS regression line was found, which was mostly dependent on the basic disease. Surprisingly, spastic patients, who have reduced strength and additionally spasticity in clinical examination, and flaccid neurologic patients showed the same offset. Patients with additional lack of trunk control (Tetraplegia) showed the largest offset. CONCLUSION Gait kinematics grossly depend on muscle strength. This was seen in patients with very different pathologies. Nevertheless, optimal correction of biomechanics and muscle strength may still not lead to a normal gait, especially in that of neurologic patients. The basic disease itself has an additional effect on gait deviations expressed as a GPS-offset of the linear regression line

Walking with a four wheeled walker (rollator) significantly reduces EMG lower-limb muscle activity in healthy subjects

To investigate the immediate effect of four-wheeled- walker(rollator)walking on lower-limb muscle activity and trunk-sway in healthy subjects.; In this cross-sectional design electromyographic (EMG) data was collected in six lower-limb muscle groups and trunk-sway was measured as peak-to-peak angular displacement of the centre-of-mass (level L2/3) in the sagittal and frontal-planes using the SwayStar balance system. 19 subjects walked at self-selected speed firstly without a rollator then in randomised order 1. with rollator 2. with rollator with increased weight-bearing.; Rollator-walking caused statistically significant reductions in EMG activity in lower-limb muscle groups and effect-sizes were medium to large. Increased weight-bearing increased the effect. Trunk-sway in the sagittal and frontal-planes showed no statistically significant difference between conditions.; Rollator-walking reduces lower-limb muscle activity but trunk-sway remains unchanged as stability is likely gained through forces generated by the upper-limbs. Short-term stability is gained but the long-term effect is unclear and requires investigation

Walking on uneven ground: How do patients with unilateral cerebral palsy adapt?

Children with cerebral palsy experience movement disorders that influence gait stability. It is likely that gait stability further decreases when walking on uneven compared to even ground. Therefore, the aim of this study was to investigate gait on uneven ground in children with unilateral cerebral palsy.; Twenty children with unilateral cerebral palsy and twenty typically developing children performed a three-dimensional gait analysis when walking on even and uneven ground. Spatio-temporal parameters, full-body joint kinematics and centre of mass displacements were compared.; On uneven versus even ground, both groups showed decreased cadence, increased stance phase and double support time, increased toe clearance height, and increased knee and hip flexion during swing phase. Whereas only the typically developing children walked slower and had increased dorsiflexion and external foot progression during stance phase, only the patients showed increased stride width, increased elbow flexion (affected and non-affected side), and kept the centre of mass more medial when standing on the affected leg.; Patients and healthy children use similar adaptation mechanisms when walking on uneven ground. Both groups increased the toe clearance height by increasing knee and hip flexion during swing. However, whereas patients enlarge their base of support by increasing stride width, healthy children do so by increasing their external foot progression angle. Furthermore, patients seem to feel more insecure and hold their arms in a position to prepare for falls on uneven ground. They also do not compensate with their non-affected side for their affected side on uneven ground

Visual targeting one step before force plates has no effect on gait parameters in orthopaedic patients during level walking

In clinical gait analysis, it is challenging to acquire usable force plate data for a patient in a limited amount of time. The aim of this study was to compare three measurement protocols, to investigate if any one of them was more time-efficient than the others at collecting kinetic data. Three conditions were compared for 15 orthopaedic patients: 1) approaching the force plate with four steps, 2) approaching the force plate with six steps, and 3) approaching the force plate with four steps while stepping on a target one step before the first force plate. Then, the following characteristics were analysed: the rate of usable force plate steps, the spatio-temporal parameters, the full-body gait kinematics, and the lower body kinetics. For the condition with four steps and targeting, the rate of usable force plate steps was highest: 84% (6.8 usable trials out of 8.1 trials on average per patient). Left hip adduction and rotation, right shoulder flexion, and total left hip power were the gait parameters with statistically significant differences between the four and six step approach. Left cadence, right step time, left thorax lateroflexion, left shoulder abduction, total right knee power, hip rotation, thorax tilt, and head tilt on both sides were statistically different between the four step approach with targeting and without targeting. None of the differences in gait parameters (except for head tilt) were of clinical relevance. Therefore, approaching the force plate with four steps and stepping on a foot-sized target one step prior to stepping on the force plate increases the rate of usable kinetic data