Reproducibility evaluation of gross and net walking efficiency in children with cerebral palsy

In evaluating energy cost (EC) of walking, referred to as walking efficiency, the use of net measurement protocols (i.e. net=gross-resting) has recently been recommended. However, nothing is known about the comparative reproducibility of net protocols and the commonly used gross protocols. Ten minutes of resting and 5 minutes of walking at a self-selected speed were used to determine gross and net EC in 13 children with spastic cerebral palsy (CP; seven males, six females; mean age 8y 7mo [SD 3y 4mo], range 4y 1mo-13y) and in 10 children (three males, seven females) with typical development. In the former, their Gross Motor Function Classification System levels ranged from Level I to Level III; and seven had hemiplegia and six diplegia. There were four repeated sessions on different days, with periods of 1 week between sessions. Reproducibility was assessed for speed, and gross and net EC, by using the standard error of measurement. The results of this preliminary study showed that EC measurements were more variable for children with CP than for children with typical development. Furthermore, in both groups there was considerably more variability in the net measurements than in the gross measurements. We conclude that, on the basis of the methodology used, the use of gross EC, rather than net EC, seems a more sensitive measure of walking efficiency to detect clinically relevant changes in an individual child with C

Energy demands of walking in persons with postpoliomyelitis syndrome: relationship with muscle strength and reproducibility

OBJECTIVES: To describe the energy demands of walking in subjects with postpoliomyelitis syndrome (PPS) in comparison with the demands in healthy subjects, and to assess the reproducibility of walking energy measurements. DESIGN: Four repeated measurements with a 1-week interval between each measurement. SETTING: Outpatient clinic of a university hospital. PARTICIPANTS: Fourteen subjects with PPS and 14 age- and sex-matched healthy subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Walking speed and energy cost of walking. The correlation parameter was lower-extremity muscle strength sum (MSS). The reproducibility parameters were standard error (SE) of measurement and smallest detectable difference (SDD). RESULTS: Walking speed in subjects with PPS (61.8 m/min) was significantly lower (-28%) and energy cost (4.8 J.kg(-1).m(-1)) was significantly higher (40%) than in healthy subjects. MSS correlated strongly with energy cost (r=-.84, P=.000), explaining 71% of the variance. The SE of measurement of energy cost measurements ranged between 1.7% and 3.4% for PPS subjects and between 1.2% and 2.4% for healthy subjects. The SDD ranged between 4.6% and 9.4% for PPS subjects and between 3.3% and 6.6% for healthy subjects, depending on the number of repeated measurements that were considered. CONCLUSIONS: Energy cost of walking in subjects with PPS is strongly related to the extent of muscle weakness in the lower extremities. Although variability was greater for PPS subjects than for healthy subjects, reproducibility of energy cost measurements was high. Therefore, metabolic assessment of energy cost of walking is a sensitive tool that can reveal clinically relevant changes even in the condition of a person with PP

Effect of ankle-foot orthoses on walking efficiency and gait in children with cerebral palsy

OBJECTIVE: To determine the effect of ankle-foot orthoses on walking efficiency and gait in a heterogeneous group of children with cerebral palsy, using barefoot walking as the control condition. DESIGN: A retrospective study. METHODS: Barefoot and ankle-foot orthosis data for 172 children with spastic cerebral palsy (mean age 9 years; hemiplegia: 21, diplegia: 97, and quadriplegia: 54) were compared. These data consisted of non-dimensional speed, net non- dimensional energy cost of walking (NN-cost), and NN-cost as a percentage of speed-matched controls (NN-cost(pct)). For 80 of these children the Gillette Gait Index and data for 3D gait kinematics and kinetics were also analyzed. RESULTS: Speed was 9% faster (p <0.001), NN-cost was 6% lower (p=0.007), and NN-cost(pct) was 9% lower (p=0.022) when walking with an ankle-foot orthosis. The Gillette Gait Index remained unchanged (p=0.607). Secondary subgroup analysis for involvement pattern showed a significant improvement in NN-cost(pct) only for quadriplegics (20%, p=0.004), whereas it remained unchanged for patients with hemiplegia and diplegia. Changes in the minimum knee flexion angle in stance phase and in terminal swing were found to be significantly related to the change in NN-cost(pct) (p=0.013 and p=0.022, respectively). CONCLUSION: The use of an ankle-foot orthosis resulted in a significant decrease in the energy cost of walking of quadriplegic children with cerebral palsy, compared with barefoot walking, whereas it remained unchanged in hemiplegic and diplegic children with cerebral palsy. Energy cost reduction was related to both a faster and more efficient walking pattern. The improvements in efficiency were reflected in changes of stance and swing phase knee motion, i.e. those children whose knee flexion angle improved toward the typical normal range demonstrated a decrease in energy cost of walking, and vice vers

Self-reported functional ambulation is related to physical mobility status in polio survivors; a cross-sectional observational study

Background: The condensed 3-level version of the self-reported ambulation classification by Perry is a validated, simple-to-use instrument in clinical practice to classify functional ambulation. Objective: To further validate the clinical meaning of the classification for polio survivors, we compared physical mobility status across 3 functional ambulation categories and investigated the relation between physical mobility and functional ambulation category. Methods: We investigated a convenience sample of 140 individuals with polio [mean (SD) age 59.4 (12.1) years; 74 men] who were able to walk at least indoors. For indicators of physical mobility status, we assessed the walked distance (m) and walking energy cost (Jkg −1m −1) during a 6-min walk test at a comfortable speed. Furthermore, self-reported physical functioning and fatigue were assessed with the 36-item Short Form Health Survey physical functioning scale (SF36-PF) and Fatigue Severity Scale (FSS), respectively. Self-reported functional ambulation was classified as household walker, limited community walker or full community walker. Results: The mean (SD) walked distance, energy cost, and SF36-PF and FSS scores significantly differed between household walkers (n = 48) and limited community walkers (n = 63) [275 (67) m; 6.35 (1.80) Jkg −1m −1; 27.7 (13.5), 5.53 (1.06), respectively, and 323 (73) m; 5.49 (1.50) Jkg −1m −1; 40.1 (15.1); 4.81 (1.38) (P < 0.018)] and full community walkers (n = 29) [383 (66) m; 4.68 (0.85) Jkg −1m −1; 63.9 (18.5), 3.85 (1.54) (P < 0.001)], with significant differences also present between limited and full community walkers (P < 0.05). Walked distance and SF36-PF score were significantly associated with functional ambulation level, determining 46% of the variance in ambulation level. Conclusion: The simple, self-reported classification of functional ambulation in 3 levels is clinically meaningful for polio survivors because it consistently corresponds to differences in objective and self-reported indicators of physical mobility and, as such, can be used to better manage rehabilitation treatment

Validity and reproducibility of C-Mill walking-adaptability assessment in polio survivors

Background: The C-Mill interactive treadmill allows for a safe walking-adaptability assessment, unveiling reduced walking adaptability in polio survivors compared to healthy individuals, possibly related to their high fall rate. However, evidence on its validity and reproducibility is scarce. Research question: What is the validity and reproducibility of C-Mill walking-adaptability assessment in polio survivors? Methods: Polio survivors with a history and/or fear of falling (n = 46) performed two walking-adaptability assessments, 1–2 weeks apart, including target-stepping tests (with 0%, 20% and 30% inter-target variance) and obstacle-avoidance tests (anticipatory and reactive). We examined (1) face validity by determining Group effects (for subgroups stratified for fall frequency, fear of falling and leg muscle weakness) and Condition effects (for difficulty level) on walking-adaptability outcomes, (2) construct validity by correlating walking-adaptability and balance outcomes, and (3) content validity by establishing possible ceiling effects. We determined whether face-validity findings were reproducible over test occasions and calculated Intraclass Correlation Coefficients (ICC) and the 95% Limits of Agreement (LoA) for walking-adaptability outcomes. Results: Walking-adaptability outcomes differed in to-be-expected directions for subgroups stratified for fall frequency and leg muscle weakness and for difficulty levels, all reproducible over test occasions. Correlations between walking-adaptability and balance outcomes were mainly low (r < 0.587). Ceiling effects were present for anticipatory obstacle-avoidance and balance outcomes, but not for reactive obstacle avoidance. ICCs [95% confidence intervals] were good for the challenging 20% (0.80[0.67–0.88]) and 30% target-stepping conditions (0.74[0.57–0.85]) and for the reactive obstacle-avoidance (0.76[0.59–0.86]) condition, but not for 0% target-stepping and anticipatory obstacle–avoidance (ICC<0.62) conditions. Likewise, the narrowest LoA were observed for the 20% and 30% target-stepping conditions. Significance: We proved face, construct and content validity of C-Mill walking-adaptability assessment in polio survivors with a history of falls and/or fear of falling. Adding walking-adaptability assessment, particularly the more challenging tests given their superior reproducibility, to currently used clinical tests could improve fall-risk evaluation in this population

Factors Associated With Walking Adaptability and Its Relationship With Falling in Polio Survivors

Objective: To explore factors associated with walking adaptability and associations between walking adaptability and falling in polio survivors. Design: Cross-sectional study. Setting: Outpatient expert polio clinic. Participants: Polio survivors (N=46) who fell in the previous year and/or reported fear of falling. Interventions: Not applicable. Main Outcome Measures: Walking adaptability was assessed on an interactive treadmill and operationalized as variable target-stepping and reactive obstacle avoidance performance. Further, we collected walking speed and assessed leg muscle strength, balance performance (Berg Balance Scale and Timed-Up-and-Go Test), balance confidence (Activities-specific Balance Confidence scale), ambulation level, orthosis use, fear of falling, and number of falls in the previous year. Results: With walking speed included as a covariate, muscle weakness of the most affected leg and balance confidence explained 54% of the variance in variable target-stepping performance. For reactive obstacle avoidance performance, muscle weakness of the most affected leg and knee extensor strength of the least affected leg explained 32% of the variance. Only target-stepping performance was significantly related to the number of falls reported in the previous year (R2=0.277, P<.001) and mediated the relation between leg muscle weakness and balance confidence with falling. Conclusion: Our exploratory study suggests that leg muscle weakness and reduced balance confidence limit walking adaptability in polio survivors. Because poorer target stepping rather than obstacle avoidance performance was associated with falling, our results indicate that a limited ability to ensure safe foot placement may be a fall risk factor in this group. These findings should be confirmed in a larger sample

Description of orthotic properties and effect evaluation of ankle-foot orthoses in non-spastic calf muscle weakness

Objective: To describe the orthotic properties and evaluate the effects of ankle-foot orthoses for calf muscle weakness in persons with non-spastic neuromuscular disorders compared with shoes-only. Design: Cross-sectional study. Subjects: Thirty-four persons who used ankle-foot orthoses for non-spastic calf muscle weakness. Methods: The following orthotic properties were measured: ankle-foot orthosis type, mass, and ankle and footplate stiffness. For walking with shoes- only and with the ankle-foot orthoses, walking speed, energy cost and gait biomechanics were assessed. Results: Four types of ankle-foot orthosis were identified: shaft-reinforced orthopaedic shoes (n = 6), ventral ankle-foot orthoses (n = 10), dorsal leaf ankle-foot orthoses (n = 12) and dorsiflexion-stop ankle-foot orthoses (n = 6). These types differed significantly with regards to mass, ankle-and footplate stiffness. Compared with shoes-only, all anklefoot orthoses/orthopaedic shoes groups combined increased walking speed by 0.18 m/s (95% confidence interval (95% CI) 0.13-0.23), reduced energy cost by 0.70 J/kg/m (95% CI 0.48-0.94) and limited ankle dorsiflexion by -3.0° (95% CI 1.3-4.7). Higher ankle-foot orthoses ankle stiffness correlated with greater reductions in walking energy cost and maximal ankle dorsiflexion angle. Conclusion: Ankle-foot orthoses for persons with non-spastic calf muscle weakness vary greatly in properties and effects on gait. The large variation in effectiveness may be due to differences in ankle stiffness, although this requires further prospective evaluation.</p

Precision orthotics: optimising ankle foot orthoses to improve gait in patients with neuromuscular diseases; protocol of the PROOF-AFO study, a prospective intervention study

In patients with neuromuscular disorders and subsequent calf muscle weakness, metabolic walking energy cost (EC) is nearly always increased, which may restrict walking activity in daily life. To reduce walking EC, a spring-like ankle-foot-orthosis (AFO) can be prescribed. However, the reduction in EC that can be obtained from these AFOs is stiffness dependent, and it is unknown which AFO stiffness would optimally support calf muscle weakness. The PROOF-AFO study aims to determine the effectiveness of stiffness-optimised AFOs on reducing walking EC, and improving gait biomechanics and walking speed in patients with calf muscle weakness, compared to standard, non-optimised AFOs. A second aim is to build a model to predict optimal AFO stiffness. A prospective intervention study will be conducted. In total, 37 patients with calf muscle weakness who already use an AFO will be recruited. At study entry, participants will receive a new custom-made spring-like AFO of which the stiffness can be varied. For each patient, walking EC (primary outcome), gait biomechanics and walking speed (secondary outcomes) will be assessed for five stiffness configurations and the patient's own (standard) AFO. On the basis of walking EC and gait biomechanics outcomes, the optimal AFO stiffness will be determined. After wearing this optimal AFO for 3 months, walking EC, gait biomechanics and walking speed will be assessed again and compared to the standard AFO. The Medical Ethics Committee of the Academic Medical Centre in Amsterdam has approved the study protocol. The study is registered at the Dutch trial register (NTR 5170). The PROOF-AFO study is the first to compare stiffness-optimised AFOs with usual care AFOs in patients with calf muscle weakness. The results will also provide insight into factors that influence optimal AFO stiffness in these patients. The results are necessary for improving orthotic treatment and will be disseminated through international peer-reviewed journals and scientific conference

Ankle-foot orthoses that restrict dorsiflexion improve walking in polio survivors with calf muscle weakness

In polio survivors with calf muscle weakness, dorsiflexion-restricting ankle-foot orthoses (DR-AFOs) aim to improve gait in order to reduce walking-related problems such as instability or increased energy cost. However, evidence on the efficacy of DR-AFOs in polio survivors is lacking. We investigated the effect of DR-AFOs on gait biomechanics, walking energy cost, speed, and perceived waking ability in this patient group. Sixteen polio survivors with calf muscle weakness underwent 3D-gait analyses to assess gait biomechanics when walking with a DR-AFOs and with shoes only. Ambulant registration of gas-exchange during a 6 min walk test determined walking energy cost, and comfortable gait speed was calculated from the walked distance during this test. Perceived walking ability was assessed using purposely-designed questionnaires. Compared with shoes-only, walking with the DR-AFOs significantly increased forward progression of the center of pressure (CoP) in mid-stance and it reduced ankle dorsiflexion and knee flexion in mid- and terminal stance (p < 0.05). Furthermore, walking energy cost was lower (-7%, p = 0.052) and gait speed was higher (p = 0.005). Patients were significantly more satisfied, felt safer, and less exhausted with the DR-AFO, compared to shoes-only (p < 0.05). DR-AFO effects varied largely across patients. Patients who walked with limited forward CoP progression and persisting knee extension during the shoes-only condition seemed to have benefitted least from the DR-AFO. In polio survivors with calf muscle weakness, DR-AFOs improved gait biomechanics, speed, and perceived walking ability, compared to shoes-only. Effects may depend on the shoes-only gait pattern, therefore further study is needed to determine which patients benefit most from the DR-AF