Summary

The foot is key in human walking, which is essential for the development of activities of daily living, and ensures a full and autonomous life. This ability may be affected by different pathologies, such as those derived from extreme postural indices (highly pronated or supinated feet), which have a high prevalence in today's population. Orthotics are frequently used to face these pathologies. Different types of plantar support designs are used in clinical practice (Root’s functional orthosis, Blake’s inverted orthosis, Kirby’s Medial Heel Skive, and variations of these types), depending on the school and previous experience. These plantar supports aim to correct posture in order to reduce the joint moments, and to avoid high pressure areas. However, patients report discomfort in many cases, and injuries may occur as a side effect.

In the last decade, different studies have pointed the interest in studying how these plantar supports affect the foot mechanics. However, kinetic studies are scarce and limited to the analysis of the ankle in the frontal plane. It should be noted that there are specific sports footwear for pronator feet, but they have only been studied for these sports conditions, which are very different from those required for gait.

In general, the kinetic studies of the foot are scarce, they focus on partial aspects, and results are hardly comparable, since they study different parameters, corresponding to different events during the gait cycle. This is due to the complexity of the problem, which involves the simultaneous analysis of the temporal evolution of multiple joint angles and moments (in different anatomical planes and in different joints). The applicant research group is a pioneer in the use of analysis methods that allow to reduce this complexity, such as dynamic stiffness and dimensional reduction techniques from the identification of kinematic and kinetic synergies, which have been used in previous works for the characterization of the dynamics of the bare foot, with different postural indices.

The aim of this project is to contribute to deepen the knowledge of the effect of the design parameters of plantar supports and/or shoe soles on the kinetic behaviour of feet with different postural indices during gait, by using methods that reduce the complexity of the problem. On the one hand, the dynamic stiffness and net work will be characterized from the analysis of kinematics and moments on the ankle, midtarsal and metatarsophalangeal joints, in the three anatomical planes, and in the following situations: barefoot, neutral footwear, specific sports footwear, and plantar supports and/or wedges with varied design parameters. And on the other hand, these same data will be used to identify the synergies and gait patterns in feet with different postural indices. As a result, guides will be developed for the selection of the proper design parameters of the plantar supports for the different postural indices, as well as for the design of specific footwear, in order to chase for a better quality of life and lower risk of injury. These guides will be of interest to footwear companies, since they will provide key information for the development of specific footwear for feet with different postural indices, a market segment that has yet to be exploited. The characterization data can also be used by rehabilitators and surgeons to adjust rehabilitation strategies and surgical practices. Finally, the experimentation and analysis techniques can be extrapolated to other works aimed to characterize the kinetics of the foot joints, especially in relation to the experimentation in footwear conditions, and to the analysis using dimensional reduction.