Effect of carbon-composite knee-ankle-foot orthoses on walking efficiency and gait in former polio patients

Objective: To investigate the effects of total-contact fitted carbon-composite knee-ankle-foot orthoses (KAFOs) on energy cost of walking in patients with former polio who normally wear a conventional leather/metal KAFO or plastic/metal KAFO. Design: A prospective uncontrolled study with a multiple baseline and follow-up design. Follow-up measurements continued until 26 weeks after intervention. Participants: Twenty adults with polio residuals (mean age 55 years). Intervention: Each participant received a new carbon-composite KAFO, fitted according to a total-contact principle, which resulted in a rigid, lightweight and well-fitting KAFO. Outcome measures: Energy cost of walking, walking speed, biomechanics of gait, physical functioning and patient satisfaction. Results: The energy cost decreased significantly, by 8%, compared with the original KAFO. Furthermore, the increment in energy cost during walking with the carbon-composite KAFO was reduced by 18% towards normative values. An improvement in knee flexion, forward excursion of the centre of pressure, peak ankle moment, and timing of peak ankle power were significantly associated with the decrease in energy cost. Walking speed and physical functioning remained unchanged. Conclusion: In patients with former polio, carbon-composite KAFOs are superior to conventional leather/metal and plastic/metal KAFOs with respect to improving walking efficiency and gait, and are therefore important in reducing overuse and maintaining functional abilities in polio survivor

Coactivation During Dynamometry Testing in Adolescents With Spastic Cerebral Palsy

BACKGROUND: Dynamometry has been used extensively to measure knee extensor strength in individuals with cerebral palsy (CP). However, increased coactivation can lead to underestimation of knee extensor strength and, therefore, reduce validity of strength measurements. It is yet unknown to what extent coactivation occurs during dynamometry testing and whether coactivation is influenced by severity of CP, load levels, and muscle fatigue. OBJECTIVES: The aims of this study were: (1) to investigate coactivation in adolescents with and without CP during dynamometer tests and (2) to assess the effect of Gross Motor Function Classification System (GMFCS) level, load level, and muscle fatigue on coactivation. DESIGN: A cross-sectional observational design was used. METHOD: Sixteen adolescents with CP (GMFCS levels I and II: n=10/6; age range=13-19 years) and 15 adolescents without CP (n=15; age range=12-19 years) performed maximal isometric contractions (maximal voluntary torque [MVT]) and a series of submaximal dynamic contractions at low (±65% MVT), medium (±75% MVT), and high (±85% MVT) loads until fatigue. A coactivation index (CAI) was calculated for each contraction from surface electromyography recordings from the quadriceps and hamstring muscles. RESULTS: Adolescents with CP classified in GMFCS level II showed significantly higher CAI values than adolescents classified in GMFCS level I and those without CP during maximal and submaximal contractions. No differences were observed among load levels. During the series of fatiguing submaximal contractions, CAI remained constant in both the CP group and the group with typical development (TD), except for adolescents with TD at the low-load condition, which showed a significant decrease. LIMITATIONS: Electromyography tracings were normalized to amplitudes during maximal isometric contractions, whereas previous studies suggested that these types of contractions could not be reliably determined in the CP population. CONCLUSION: Coactivation was higher in adolescents with CP classified in GMFCS level II than in adolescents with TD and those with CP in GMFCS level I at different load levels. Within all groups, coactivation was independent of load level and fatigue. In individuals with CP, coactivation can lead to an underestimation of agonist muscle strength, which should be taken into account while interpreting the results of both maximal and submaximal dynamometer tests

Relations between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy

Aim: To investigate the relation between muscle endurance and subjectively reported fatigue, walking capacity, and participation in mildly affected adolescents with cerebral palsy (CP) and peers with typical development. Method: In this case–control study, knee extensor muscle endurance was estimated from individual load–endurance curves as the load corresponding to a 15-repetition maximum in 17 adolescents with spastic CP (six males, 11 females; age 12–19y) and 18 adolescents with typical development (eight males, 10 females; age 13–19y). Questionnaires were used to assess subjectively reported fatigue (Pediatric Quality of Life Inventory Multidimensional Fatigue Scale) and participation (Life-Habits questionnaire). Walking capacity was assessed using the 6-minute walk test. Relations were determined using multiple regression analyses. Results: Muscle endurance related significantly to subjectively reported fatigue and walking capacity in adolescents with CP, while no relations were found for adolescents with typical development (subjectively reported fatigue: regression coefficient β [95% confidence intervals] for CP=23.72 [6.26 to 41.18], for controls=2.72 [−10.26 to 15.69]; walking capacity β for CP=125m [−87 to 337], for controls=2m [−86 to 89]). The 15-repetition maximum did not relate to participation in adolescents with CP. Interpretation: Subjectively reported fatigue and reduced walking capacity in adolescents with CP are partly caused by lower muscle endurance of knee extensors. Training of muscle endurance might contribute to reducing the experience of fatigue and improving walking capacity. Reduced muscle endurance seems to have no effect on participation