Effects of Foot Orthoses Extrinsic Rearfoot and Forefoot Posts on Muscle Activity During Walking: A Case Study

摘要

Introduction: In clinical practice, different types of rearfoot and forefoot extrinsic posts are regularly added to foot orthoses (FOs) to make the treatment more specific. However, to this day, their effects on muscle activity during walking are still unclear and few studies have quantified them. The purpose of this case study was to quantify the effects of FOs with different extrinsic rearfoot and forefoot posts on muscle activity during walking to generate hypotheses with the goal to develop a more complex experimental design for further studies. Materials and Methods: A 26-year-old man with hyperpronated feet was recruited to walk on a 5-meter walkway with seven pairs of FOs with different extrinsic rearfoot and forefoot posts (no post, external oblique rearfoot post, internal oblique rearfoot post, straight rearfoot post, rearfoot and forefoot posts, rearfoot and forefoot posts at 2° varus, and rearfoot and forefoot posts at 5° varus). Mean activity of eight lower-limb muscles (gluteus medius, vastus lateralis, vastus medialis, biceps femoris, medial gas-trocnemius, lateral gastrocnemius, fibularis longiis, and tibialis anterior) was analyzed during the three phases of the walking cycle (contact, midstance, and propulsion). Peak root mean square (RMS) amplitude was also measured. Results: Significant differences were observed between the control and the experimental conditions for mean muscle activity and peak RMS amplitude during the gait cycle. Results were variable between conditions. However, in general, more muscle activity was observed when increasing the frontal plane inclination of the extrinsic rearfoot and forefoot posts. Conclusions: The addition of extrinsic rearfoot and forefoot posts to the FOs can modulate muscle function during walking. However, to this day, not enough data are available to build a clinical guideline, and it is still unknown if they can have positive effects on musculoskeletal pathologies of the lower limb.