Hilde E. Ploeger

This retrospective study evaluated the associations between change in energy cost of walking and changes in ankle and knee kinematics and kinetics when wearing a dorsiflexion-restricting ankle-foot orthosis compared with shoes alone in polio survivors with calf muscle weakness. All polio survivors with unilateral calf muscle weakness who were provided with a custom-made dorsiflexion-restricting ankle-foot orthosis and who had undergone a walking energy cost test and gait analysis test between April 2006 and January 2020 were included in the analysis (n = 26). Associations between change in energy cost (obtained during a 6-minute walking test with gas-exchange assessment) and changes in ankle and knee biomechanical parameters (obtained with three-dimensional gait analysis) from shoes alone to walking with the orthosis were tested using Pearson's correlations. Reduced energy cost of walking was significantly correlated with increased maximum internal ankle plantarflexion moment (r=-0.453, 95%CI [-0.695;-0.041], p = 0.023) and increased forward center of pressure progression (r=-0.416, 95%CI [-0.723;0.009], p = 0.034) during mid-stance. In polio survivors with unilateral calf muscle weakness, the reduction in energy cost of walking while wearing an ankle-foot orthosis appears to depend on its ability to improve the ankle plantarflexion moment and forward progression of the center of pressure during mid-stance.

Background: Lower limb orthoses intend to improve walking in adults with neuromuscular disorders (NMD). Yet, reported group effects of lower limb orthoses on treatment outcomes have generally been small and heterogeneous. We propose that guideline-based orthotic care within a multidisciplinary expert setting may improve treatment outcomes. Aim: To examine the effectiveness of specialist care orthoses compared to usual care orthoses on personal goal attainment and walking ability. Design: Cohort study. Population: Adults with NMD who experienced walking problems due to calf and/or quadriceps muscle weakness and were provided with a specialist care lower limb orthosis between October 2011 and January 2021. Methods: Three months after provision, the specialist care orthosis was compared to the usual care orthosis worn at baseline in terms of personal goal attainment (Goal Attainment Scaling (GAS)), comfortable walking speed (m/s), net energy cost (J/kg/m) (both assessed during a 6-minute walk test), perceived walking ability and satisfaction. Results: Sixty-four adults with NMD were eligible for analysis. The specialist care orthoses comprised 19 dorsiflexion-restricting ankle-foot orthoses (AFOs), 22 stance-control knee-ankle-foot orthoses (KAFOs) and 23 locked KAFOs. Overall, 61% of subjects showed a clinically relevant improvement in GAS score. Perceived safety, stability, intensity, fear of falling and satisfaction while walking all improved (p≤0.002), and subjects were satisfied with their specialist care orthosis and the services provided. Although no effects on walking speed or net energy cost were found in combined orthosis groups, specialist care AFOs significantly reduced net energy cost (by 9.5%) compared to usual care orthoses (from mean (SD) 3.81 (0.97) to 3.45 (0.80) J/kg/m, p = 0.004). Conclusion: Guideline-based orthotic care within a multidisciplinary expertise setting could improve treatment outcomes in adults with NMD compared to usual orthotic care by improvements in goal attainment and walking ability. A randomized controlled trial is now warranted to confirm these results.

Dorsiflexion-restricting ankle-foot orthoses (DR-AFOs) are often prescribed in polio survivors with calf muscle weakness to reduce or solve gait problems. However, orthoses are sometimes not being used and/or users are dissatisfied with the usability. To compare the usability of custom-made DR-AFOs provided in clinical care between users and discontinued users who have calf muscle weakness due to polio. Cross-sectional survey. Outpatient post-polio university hospital clinic in the Netherlands. All polio survivors with calf muscle weakness, provided with a DR-AFO between 2004 and 2015 in our outpatient clinic. DR-AFO use and usability according to the ISO 9241-11 standard were evaluated with a questionnaire sent out by postal mail. Forty of 57 questionnaires were returned. Five respondents did not fulfil the eligibility criteria. DR-AFO use among the 35 eligible respondents was 74%. Compared to discontinued users, users were significantly more often male (users: 16 of 26 vs. discontinued users: 0 of 9, P=0.001), more limited in their walking ability without DR-AFO (P=0.007), perceived more effectiveness, both overall (P=0.001) and on their personal goals of use (P=0.006), and were more satisfied with orthosis-related aspects (P=0.011), such as comfort. Almost three quarters of the polio survivors used their orthosis. Use was related to several aspects of usability, indicating that it is important to consider usability in the prescription process of DR-AFOs for polio survivors with calf muscle weakness. When prescribing DR-AFOs, it is important to consider that the orthosis is most likely used when the experienced walking problems are large and the DR-AFO reduces these problems. We recommend discussing the patient's personal goals for DR-AFO use and the anticipated improvement on the individual's walking problems as well as possible hindrance of the orthosis during daily life activities. Furthermore, providers may need to pay extra attention to females and should particularly take care that the experienced fit and comfort are satisfactory. Incorporating these suggestions in clinical practice may further improve DR-AFO use among polio survivors with calf muscle weakness.

Background: To reduce gait problems in individuals with non‐spastic calf muscle weakness, spring‐like ankle‐foot orthoses (AFOs) are often applied, but they are not individually optimized to treatment outcome. The aim of this proof‐of‐concept study was to evaluate the effects of modifying the stiffness for two spring‐like AFO types with shoes‐only as reference on gait outcomes in three individuals with calf muscle weakness due to polio.Methods: We assessed 3D gait biomechanics, walking speed and walking energy cost for shoes‐only and five stiffness conditions of a dorsal‐leaf‐spring AFO and a spring‐hinged AFO. Outcomes were compared between stiffness conditions in the two AFOs and three subjects.Results: Maximum ankle dorsiflexion angle decreased with increasing stiffness in both AFOs (up to 6–8°) and all subjects. Maximum knee extension angle changed little between stiffness conditions, however different responses between the AFOs and subjects were observed compared to shoes‐only. Walking speed remained unchanged across conditions. For walking energy cost, we found fairly large differences across stiffness conditions with both AFOs and between subjects (range 3–15%).Conclusions: Modifying AFO stiffness in individuals with non‐spastic calf muscle weakness resulted in substantial differences in ankle biomechanics and walking energy cost with no effect on speed. Our results provide proof‐of‐concept that individually optimizing AFO stiffness can clinically beneficially improve gait performance.