aspects of gait
Aside from general lack of motor control and issues with weakness and balance, other more specific variables contribute to the irregular gait of the cerebral palsied. The joints of a person with cerebral palsy – especially the knee and ankle joints – tend to function improperly, leading to reduced joint angular velocities and disrupted torque dynamics. Muscles and tendons also contribute to problems with gait in cerebral palsy, displaying excessive (e.g., spastic) and inappropriate activity. Some people with the disease also show a stride that lacks one or more of the three functional rockers, the heel, the ankle, and the forefoot rocker.
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1. Common gait abnormalities of the knee in cerebral palsy
Gait abnormalities in children with cerebral palsy are the consequence of contractures across joints, muscle spasticity, and phasically inappropriate muscle action. Though abnormalities involving one of the major joints of the lower extremity will usually have consequences on the function of the other joints, it is possible to recognize certain primary disorders at each joint. The most common gait abnormalities of the knee in patients with cerebral palsy occur in the sagittal plane. Based on the experience gained from performing gait analysis on more than 588 patients with cerebral palsy, four primary gait abnormalities of the knee have been identified: jump knee, crouch knee, stiff knee, and recurvatum knee. In this review, each abnormality is described by its motion analysis laboratory profile (physical examination, motion parameters, electromyography [EMG] data, and force plate data). The most common etiologies and the consequences for gait of each disorder are also considered. Appreciation of the most common pathologic patterns of gait should facilitate accurate and detailed analysis of the individual patient with gait abnormalities.
[Sutherland, D. H. & Davids, J. R. (1993). Common gait abnormalities of the knee in cerebral palsy. Clinical Orthopaedics and Related Research, 288, 139-47.]
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2. Treatment of functional limitations at the knee in ambulatory children with cerebral palsy
The gait of ambulatory children with cerebral palsy frequently involves abnormal knee motion. Spasticity, muscle contracture formation, impairments of motor control, weakness, balance deficits, and extrapyramidal motions can all contribute to the functional limitations imposed at the knee. Careful clinical evaluation of the child and their gait must be performed in order to determine the best individual course of treatment. Often, three-dimensional motion analysis with assessment of muscle activity and force is necessary to completely assess the complexities of gait. Several typical gait patterns have been described involving the knee, including 'jump knee', 'crouch', 'true equinus', 'apparent equinus', 'recurvatum' and 'stiff knee' gait. Each of these gait patterns is defined here and discussed using case examples. These typical gait patterns are usually accompanied by involvement at the hip and ankle and may be combined with transverse plane rotational abnormalities. Treatment options such as rehabilitation (physiotherapy, casting, strengthening, and/or orthoses), spasticity management (intramuscular injections of phenol, alcohol, and botulinum toxin type A) and orthopaedic approaches are discussed for each entity.
[Chambers, H. G. (2001). Treatment of functional limitations at the knee in ambulatory children with cerebral palsy. European Journal of Neurology, 8(Suppl. 5), 59-74.]
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3. Common abnormal kinetic patterns of the knee in gait in spastic diplegia of cerebral palsy
We studied the kinetic characteristics of the knee in patients with spastic diplegia. Twenty three children with spastic diplegia were recruited and had their 46 limbs categorised into the following four groups: jump (n=7), crouch (n=8), recurvatum (n=14) and mild (n=17). In the crouch pattern, the patients usually had a larger and longer lasting internal knee extensor moments in stance suggesting that rectus femoris had a relatively high activation. In the recurvatum pattern, the internal knee flexor moment was large and long lasting in stance. The biceps femoris showed less activity on EMG although the knee flexor moment was large and we concluded that the soft tissue behind the knee joint provided this flexor moment. In the jump knee pattern there was abnormal power generation at the knee and ankle joints in initial stance, which did not contribute to normal progression but aided upward body motion. In the mild group the kinetic data was similar to that seen in normal children. Knowledge of kinetic patterns in these patients may help in their subsequent management.
[Lin, C. J., Guo, F. C., Chou, Y. L. & Cherng, R. J. (2000). Common abnormal kinetic patterns of the knee in gait in spastic diplegia of cerebral palsy. Gait & Posture, 11(3), 224-32.]
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4. Joint angular velocity in spastic gait and the influence of muscle-tendon lengthening
BACKGROUND: Joint angular velocity (the rate of flexion and extension of a joint) is related to the dynamics of muscle activation and force generation during walking. Therefore, the goal of this research was to examine the joint angular velocity in normal and spastic gait and changes resulting from muscle-tendon lengthening (recession and tenotomy) in patients who have spastic cerebral palsy. METHODS: The gait patterns of forty patients who had been diagnosed with spastic cerebral palsy (mean age, 8.3 years; range, 3.7 to 14.8 years) and of seventy-three age-matched, normally developing subjects were evaluated with three-dimensional motion analysis and electromyography. The patients who had cerebral palsy were evaluated before muscle-tendon lengthening and nine months after treatment. RESULTS: The gait patterns of the patients who had cerebral palsy were characterized by increased flexion of the knee in the stance phase, premature plantar flexion of the ankle, and reduced joint angular velocities compared with the patterns of the normally developing subjects. Even though muscle-tendon lengthening altered sagittal joint angles in gait, the joint angular velocities were generally unchanged at the hip and knee. Only the ankle demonstrated modified angular velocities, including reduced dorsiflexion velocity at foot-strike and improved dorsiflexion velocity through mid-stance, after treatment. Electromyographic changes included reduced amplitude of the gastrocnemius-soleus during the loading phase and decreased knee coactivity (the ratio of quadriceps and hamstring activation) at toe-off. Principal component analyses showed that, compared with joint-angle data, joint angular velocity was better able to discriminate between the gait patterns of the normal and cerebral palsy groups. CONCLUSIONS: This study showed that muscle-tendon lengthening corrects biomechanical alignment as reflected by changes in sagittal joint angles. However, joint angular velocity and electromyographic data suggest that the underlying neural input remains largely unchanged at the hip and knee. Conversely, electromyographic changes and changes in velocity in the ankle indicate that the activation pattern of the gastrocnemius-soleus complex in response to stretch was altered by recession of the complex.
[Granata, K. P., Abel, M. F. & Damiano, D. L. (2000). Joint angular velocity in spastic gait and the influence of muscle-tendon lengthening. The Journal of Bone and Joint Surgery. American Volume, 82(2), 174-86.]
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5. Gait characteristics following Achilles tendon elongation: The foot rocker perspective
The action of three functional rockers, namely the heel, ankle and forefoot rocker, assist the progression of the leg over the supporting foot. The purpose of this case series was to analyze the occurrence of foot rockers during gait in three children with cerebral palsy (CP) who had undergone the tendo-Achilles lengthening (TAL), procedure followed by a clinic- or home-based intervention and in one child with CP without history of surgery. Self-selected gait was video-recorded in a laboratory during six testing sessions at half-year intervals rendering a 3 year period of observation. One child had pre- and post-surgical gait data and the other two had post surgical data only. Sagittal plane knee angular velocity, as well as foot to ground positions, and foot rocker occurrence were analyzed. In a child with history of CP, and without history of surgery, mean angular velocities of the 1st, 2nd and 3rd foot rocker were 3.7, 0.57 and 6.67 rad/s, respectively, and the step length and cadence were normal. In children who underwent TAL the 1st and 2nd rocker was absent, as the initial contact of the foot with the ground was either with foot-flat or forefoot. The mean velocity of the 3rd rocker in children who underwent TAL was lower by approximately 50-80% than that of the nonsurgical case. Furthermore, the characteristic pattern of the knee joint to foot-floor position during gait was not observed in these cases. Foot rocker analysis identified children with abnormal gait characteristics. Following surgery these gait characteristics remained abnormal.
[Bober, T., Dziuba, A., Kobel-Buys, K. & Kulig, K. (2008). Gait characteristics following Achilles tendon elongation: The foot rocker perspective. Acta of Bioengineering and Biomechanics, 10(1), 37-42.]
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6. Roles of reflex activity and co-contraction during assessments of spasticity of the knee flexor and knee extensor muscles in children with cerebral palsy and different functional levels
BACKGROUND AND PURPOSE: Spasticity is a common impairment in children with cerebral palsy (CP). The purpose of this study was to examine differences in passive resistive torque, reflex activity, coactivation, and reciprocal facilitation during assessments of the spasticity of knee flexor and knee extensor muscles in children with CP and different levels of functional ability. SUBJECTS: Study participants were 20 children with CP and 10 children with typical development (TD). The 20 children with CP were equally divided into 2 groups: 10 children classified in Gross Motor Function Classification Scale (GMFCS) level I and 10 children classified in GMFCS level III. METHODS: One set of 10 passive movements between 25 and 90 degrees of knee flexion and one set of 10 passive movements between 90 and 25 degrees of knee flexion were completed with an isokinetic dynamometer at 15 degrees /s, 90 degrees /s, and 180 degrees /s and concurrent surface electromyography of the vastus lateralis and medial hamstring muscles. RESULTS: Children in the GMFCS level III group demonstrated significantly more peak knee flexor torque with passive movements at 180 degrees /s than children with TD. Children in the GMFCS level I and level III groups demonstrated significantly more repetitions with medial hamstring muscle activity, vastus lateralis muscle activity, and co-contraction than children with TD during the assessment of knee flexor spasticity at a velocity of 180 degrees /s. DISCUSSION AND CONCLUSION: Children with CP and more impaired functional mobility may demonstrate more knee flexor spasticity and reflex activity, as measured by isokinetic dynamometry, than children with TD. However, the finding of increased reflex activity with no increase in torque in the GMFCS I group in a comparison with the TD group suggests that reflex activity may play a less prominent role in spasticity.
[Pierce, S. R., Barbe, M. F., Barr, A. E., Shewokis, P. A. & Lauer, R. T. (2008). Roles of reflex activity and co-contraction during assessments of spasticity of the knee flexor and knee extensor muscles in children with cerebral palsy and different functional levels. Physical Therapy, 88(10), 1124-34.]
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7. Relationship of spasticity to knee angular velocity and motion during gait in cerebral palsy
This study investigated the effects of spasticity in the hamstrings and quadriceps muscles on gait parameters including temporal spatial measures, knee position, excursion and angular velocity in 25 children with spastic diplegic cerebral palsy (CP) as compared to 17 age-matched peers. While subjects were instructed to relax, an isokinetic device alternately flexed and extended the left knee at one of the three constant velocities 30 degrees/s, 60 degrees/s and 120 degrees/s, while surface electromyography (EMG) electrodes over the biceps femoris and the rectus femoris recorded muscle activity. Patients then participated in 3D gait analysis at a self-selected speed. Results showed that, those with CP who exhibited heightened stretch responses (spasticity) in both muscles, had significantly slower knee angular velocities during the swing phase of gait as compared to those with and without CP who did not exhibit stretch responses at the joint and the tested speeds. The measured amount (torque) of the resistance to passive flexion or extension was not related to gait parameters in subjects with CP; however, the rate of change in resistance torque per unit angle change (stiffness) at the fastest test speed of 120 degrees/s showed weak to moderate relationships with knee angular velocity and motion during gait. For the subset of seven patients with CP who subsequently underwent a selective dorsal rhizotomy, knee angular extension and flexion velocity increased post-operatively, suggesting some degree of causality between spasticity and movement speed.
[Damiano, D. L., Laws, E., Carmines, D. V. & Abel, M. F. (2006). Relationship of spasticity to knee angular velocity and motion during gait in cerebral palsy. Gait & Posture, 23(1), 1-8.]
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8. Gait adaptation of children with cerebral palsy compared with control children with stepping over an obstacle
This study investigated the adaptive gait pattern in obstacle clearance in 12 normally developing (ND) children (six males, six females; mean age 10y 2mo, SD 10mo) and 12 children who had spastic diplegic cerebral palsy (CP) and who were independent ambulators (10 males, two females; mean age 13y 5mo, SD 2y 7mo). Children in both groups had 8 to 12 years of walking experience. They walked up to and crossed over obstacles of a height of 0%, 10%, and 20% of their leg length. Kinematic aspects of the three-dimensional leg movements were captured with the Vicon system and analyzed with one-way analysis of variance with repeated measure. Both groups increased foot clearance for higher obstacles. Children with CP were slower in approach and crossing speed, and used a wider base of support than the ND children when the obstacle height was increased. Results suggest that motor problems in obstacle clearance in children with CP lie in the implicit process of motor control, i.e. torque dynamics, not the explicit process, i.e. movement-match with the environmental constraints.
[Law, L. S. & Webb, C. Y. (2005). Gait adaptation of children with cerebral palsy compared with control children with stepping over an obstacle. Developmental Medicine and Child Neurology, 47(5), 321-8.]
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9. Center of mass movement and energy transfer during walking in children with cerebral palsy
OBJECTIVE: To gain insight into the mechanical inefficiencies of gait patterns used by children with spastic diplegia by analysis of center of mass (COM) movement and energy recovery. DESIGN: Prospective study using between-group measures to analyze differences between children with cerebral palsy (CP) and age-matched controls without CP. SETTING: Assessments were performed in a gait laboratory. PARTICIPANTS: Fifteen children with spastic diplegia and 6 age-matched controls without CP with a mean age of 9.7 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Gait data assessed included temporal-distance factors, COM vertical excursion, work done on the COM, and the percentage of energy transferred and relative phase between the potential and kinetic energy. RESULTS: Children with CP had a 33% smaller energy recovery factor than the controls (P<.001). They also had 60% greater COM vertical excursion (P<.02) and a poorer phasic relation between potential and kinetic energies (P<.02), both of which contributed to greater mechanical work performed (P<.003). CONCLUSIONS: Compared with the age-matched controls without CP, the children with CP were mechanically less efficient in their gait. Interventions that promote heel contact and roll over and greater knee stability to better utilize the kinetic energy of push-off could improve walking efficiency.
[Bennett, B. C., Abel, M. F., Wolovick, A., Franklin, T., Allaire, P. E. & Kerrigan, D. C. (2005). Center of mass movement and energy transfer during walking in children with cerebral palsy. Archives of Physical Medicine and Rehabilitation, 86(11), 2189-94.]
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10. Determinants of gait as applied to children with cerebral palsy
In the present study, we quantified the isolated contributions of eight determinants of gait on the vertical center of mass (CoM) displacement of both typically developing children and children with cerebral palsy (CP). The role of these determinants, on vertical excursion, has never been examined for children or children with CP. We hypothesized that the relative contributions of the determinants to vertical CoM excursion of children with CP would be the same as the age-matched controls. We found that based on the similarities in the determinants effect on gait between the controls and adults reflect that children of this age walk with a mature gait. When applied to subjects with CP the determinant analysis found similar, but slightly exaggerated effects of those of the controls. All determinants that negatively affect CoM excursion were significantly worse in the children with CP, while those determinants that decreased excursion were varied. Heel rise, single support knee flexion, and pelvic obliquity had similar effects for on both groups. Pelvic rotation resulted in more excursion reduction in the controls, while leg inclination was more beneficial in reducing the CP groups excursion. The main cause for increased vertical excursion of the CoM in the children with CP was the increased knee flexion of both legs during double support. This excessive lowering of the CoM means that extra work is done to raise the CoM over the single support leg. The situation is aggravated by the fact that the CoM was lifted higher than typical because of the heel lifting during single support. Although these determinants allow quantification of the effects of gait kinematics and provide some useful information for gait they are limited in their ability to quantify the dynamics and kinetics of gait that are important for individuals with walking disabilities.
[Russell, S. D., Bennett, B. C., Kerrigan, D. C. & Abel, M. F. (2007). Determinants of gait as applied to children with cerebral palsy. Gait & Posture, 26(2), 295-300.]
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11. Effect of functional electrical stimulation, applied during walking, on gait in spastic cerebral palsy
This study investigated the effect of functional electrical stimulation (FES), applied during walking, on the gait of children with spastic cerebral palsy (CP). Eight children (five males, three females; mean age 13y 2mo, SD 2y 2m; range 8y 11mo to 17y 6mo) diagnosed with diplegic (n=6) or hemiplegic (n=2) spastic CP completed the study. All participants were ambulant. Core FES strategies based on common CP gait deviations were developed and tailored for each child. FES strategies for each child were evaluated in two separate test sessions. Effects of FES on gait were monitored with three-dimensional motion analysis. Within each test session each child's gait was assessed when walking without FES (phase A) and with FES (phase B). An A-B-A-B test sequence was employed allowing the effects of the withdrawal and reinstatement of FES to be assessed. All children performed 10 consecutive walks in each phase. Replication of this sequence on a separate day allowed the repeatability of the intervention to be evaluated. Outcome measures, including summary variables of kinematic data, temporal-spatial variables, and mode of initial contact, were predefined for each child and targets for clinical significance were set for these outcome measures. Comparisons were performed between these targets and the actual outcomes. Consistent clinically significant improvements were recorded for three children: one child showed some improvement that was statistically significant but not clinically significant. Results for one child were mixed. There was no change in the remaining three children. Gait analysis proved to be a useful tool in both developing and determining the effectiveness of FES strategies.
[Postans, N. J. & Granat, M. H. (2005). Effect of functional electrical stimulation, applied during walking, on gait in spastic cerebral palsy. Developmental Medicine and Child Neurology, 47(1), 46-52.]
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