Use of gait parameters to predict the effectiveness of botulinum toxin injection in the spastic rectus femoris muscle of stroke patients with stiff knee gait.

BACKGROUND: Botulinum toxin type A (BTX-A) injection in the rectus femoris (RF) is commonly used to treat decreased peak knee flexion in swing phase of the gait in hemiplegic patients. However, the effect of BTX-A varies between 5° to 10° depending on the studies. Peak knee flexion also increases during fast gait and could constitute a way to predict the effect of BTX-A injection in the RF. AIM: To determine if changes in gait parameters during fast gait before injection could predict the effect of RF BTX-A injection on peak knee flexion in hemiplegic patients. DESIGN: Prospective observational study. SETTING: A neurological rehabilitation department in a university hospital POPULATION: Twenty two hemiplegic patients with stiff knee gait mainly due to spasticity of the RF and treated by RF-BTX-A-injection. METHODS: Patients' gait was analyzed using a 3D motion analysis system and force plates. The gait recordings were performed before (PRE-RF-BTX-A:spontaneous and fast gait speed) and one month after RF-BTX-A-injection (POST-RF-BTX-A:spontaneous gait speed). Correlations between the percentage change in gait parameters during fast gait before RF-BTX-A-injection and the percentage increase in peak knee flexion POST-RF-BTX-A injection at spontaneous speed were analyzed. RESULTS: The percentage improvement in peak knee flexion in the fast gait condition before injection was the only parameter correlated with the percentage increase in peak knee flexion POST-RF-BTX-A injection. This was confirmed by a stepwise linear regression. The percentage increase in peak knee flexion POST-RF-BTX-A injection was also correlated with the percentage increase in knee flexion angular velocity at toe-off in the fast gait condition. CONCLUSION: The percentage increase in peak knee flexion in swing during fast gait before injection is a useful predictor of the increase in peak knee flexion following RF BTX-A injection in chronic stroke patients with RF spasticity. CLINICAL REHABILITATION IMPACT: In stroke patients with SKG which is mainly caused by spasticity of the RF muscle, evaluating changes which occur during fast gait might help the therapist to identify patients who would benefit the most from BTX-A injection in the RF muscle.

Effects of a dynamic-ankle-foot orthosis (Liberté®) on kinematics and electromyographic activity during gait in hemiplegic patients with spastic foot equinus.

BACKGROUND: A dynamic-ankle-foot orthosis has recently emerged and consists of an elastic band allowing the variation of stiffness degree and adjusts dorsiflexion assistance in swing. The aim of this study was to quantify the biomechanical adaptations induced by this orthosis during gait in hemiplegic patients. METHODS: Twelve hemiplegic patients performed two gait analyses (without and with the ankle-foot orthosis). Spatiotemporal, kinematic, kinetic and electromyographic gait parameters were quantified using an instrumented gait analysis system during the stance and swing phases. RESULTS: During swing, peak ankle dorsiflexion was greater with the orthosis and associated with a decrease of pelvic obliquity angle. In stance, peak ankle plantarflexion and dorsiflexion were greater with the orthosis and associated with an increase of ankle angle at heel strike and toe-off. Electromyographic activities of both the tibialis anterior and the medial gastrocnemius were greater with the orthosis. CONCLUSIONS: This dynamic-ankle-foot orthosis improved gait in hemiplegic patients with spastic foot equinus. The spatiotemporal adaptations seem to be caused mainly by the increase of ankle dorsiflexion during stance and swing phases. The changes in electromyographic activity were related to an active dorsiflexion in stance and swing phases and an active plantarflexion in stance phase.

Isokinetic assessment of the effects of botulinum toxin injection on spasticity and voluntary strength in patients with spastic hemiparesis.

BACKGROUND: Peak knee flexion during swing phase is frequently reduced following stroke. The main treatment is botulinum toxin injection (BoNT-A) of the Rectus Femoris (RF) muscle. BoNT-A injections have been shown to decrease spasticity (assessed using the modified Ashworth scale) and to improve peak knee flexion during swing phase. Although the effect of BoNT-A has been clearly demonstrated on kinematic parameters during gait, the direct effects on spasticity and strength have been little studied using objective and sensitive outcome measures. AIM: The aim of this study was to use an isokinetic dynamometer to assess the effects of BoNT-A injection in the RF on stretch reflex-related torque at the knee joint and peak voluntary knee flexor and extensor torque and to evaluate the effect on functional capacity. DESIGN: Before-after trial: Assessments were carried out pre and post (four weeks) RF BoNT-A injection. Clinical and isokinetic evaluations were carried out. SETTING: Ambulatory care in a hospital setting. Participants. Population-based sample of fourteen chronic spastic hemiparetic patients with stiff knee gait. METHODS: Primary outcome measurements were stretch reflex-related torque at the knee joint and peak voluntary knee flexor and extensor torque. Secondary outcomes were knee angle at peak torque, the slope of the torque velocity curve, stiffness and functional outcomes. RESULTS: Peak knee extensor torque was significantly decreased and peak knee flexor torque was significantly increased during maximal voluntary concentric and isometric contractions following BoNT-A injection of the RF. Stretch reflex-related torque evaluated during passive stretching movements was reduced and the angle of occurrence of the peak was greater. Functional outcomes did not change. CONCLUSIONS AND CLINICAL REHABILITATION IMPACT: The results of this study indicate that BoNT-A injection reduced RF spasticity but also reduced quadriceps strength. In contrast, knee flexor strength increased. These changes did not, however, lead to functional gait changes.

Changes in electromyographic activity after botulinum toxin injection of the rectus femoris in patients with hemiparesis walking with a stiff-knee gait.

PURPOSE: This study was designed to evaluate the effects of botulinum toxin type-A (BoNTA) injection of the rectus femoris (RF) muscle on the electromyographic activity of the knee flexor and extensor and on knee and hip kinematics during gait in patients with hemiparesis exhibiting a stiff-knee gait. METHOD: Two gait analyses were performed on fourteen patients: before and four weeks after BoNTA injection. Spatiotemporal, kinematic and electromyographic parameters were quantified for the paretic limb. RESULTS: BoNTA treatment improved gait velocity, stride length and cadence with an increase of knee angular velocity at toe-off and maximal knee flexion in the swing phase. Amplitude and activation time of the RF and co-activation duration between the RF and biceps femoris were significantly decreased. The instantaneous mean frequency of RF was predominantly lower in the pre-swing phase. CONCLUSIONS: The results clearly show that BoNTA modified the EMG amplitude and frequency of the injected muscle (RF) but not of the synergist and antagonist muscles. The reduction in RF activation frequency could be related to increased activity of slow fibers. The frequency analysis of EMG signals during gait appears to be a relevant method for the evaluation of the effects of BoNTA in the injected muscle.

Effects of a knee-ankle-foot orthosis on gait biomechanical characteristics of paretic and non-paretic limbs in hemiplegic patients with genu recurvatum.

BACKGROUND: A knee-ankle-foot orthosis may be prescribed for the prevention of genu recurvatum during the stance phase of gait. It allows also to limit abnormal plantarflexion during swing phase. The aim is to improve gait in hemiplegic patients and to prevent articular degeneration of the knee. However, the effects of knee-ankle-foot orthosis on both the paretic and non-paretic limbs during gait have not been evaluated. The aim of this study was to quantify biomechanical adaptations induced by wearing a knee-ankle-foot orthosis, on the paretic and non-paretic limbs of hemiplegic patients during gait. METHODS: Eleven hemiplegic patients with genu recurvatum performed two gait analyses (without and with the knee-ankle-foot orthosis). Spatio-temporal, kinematic and kinetic gait parameters of both lower limbs were quantified using an instrumented gait analysis system during the stance and swing phases of the gait cycle. FINDINGS: The knee-ankle-foot orthosis improved spatio-temporal gait parameters. During stance phase on the paretic side, knee hyperextension was reduced and ankle plantarflexion and hip flexion were increased. During swing phase, ankle dorsiflexion increased in the paretic limb and knee extension increased in the non-paretic limb. The paretic limb knee flexion moment also decreased. INTERPRETATION: Wearing a knee-ankle-foot orthosis improved gait parameters in hemiplegic patients with genu recurvatum. It increased gait velocity, by improving cadence, stride length and non-paretic step length. These spatiotemporal adaptations seem mainly due to the decrease in knee hyperextension during stance phase and to the increase in paretic limb ankle dorsiflexion during both phases of the gait cycle.