Effect of heating on the mechanical properties of insole materials

Impact accelerations during a prolonged run using a microwavable self-customised foot orthosis

The use of custom-made foot orthoses has been associated with numerous benefits, such as decreased impact accelerations. However, it is not known whether this effect could be due to better customisation. The present study analysed the effects of the first generation of  a microwavable prefabricated self-customised foot orthosis vs. a prefabricated standard one on impact accelerations throughout a prolonged run. Thirty runners performed two tests of 30-min running on a treadmill, each one with an orthosis condition. Impact acceleration variables of tibia and head were recorded every 5 min. Microwavable self-customised foot orthosis increased the following variables in the first instants compared to the prefabricated standard one: tibial peak (min1: 6.5 (1.8) vs. 6.0 (1.7) g, P = .009, min5: 6.6 (1.7) vs. 6.2 (1.7) g, P = .035), tibial magnitude (min1: 8.3 (2.6) vs. 7.7 (2.4) g, P = .030, min5: 8.5 (2.6) vs. 7.9 (2.5) g, P = .026) and shock attenuation (min1: 61.4 (16.8) vs. 56.3 (16.3)%, P = .014, min5: 62.0 (15.5) vs. 57.2 (15.3)%, P = .040), and tibial rate throughout the entire run (504.3 (229.7) vs. 422.7 (212.9) g/s, P = .006). However, it was more stable throughout 30-min running (P < .05). These results show that the shape customisation entailed by the thermoformable material does not provide impact acceleration improvements.

Using a texture analyser to objectively quantify foot orthoses

BACKGROUND AND AIM

Foot orthoses alter the kinematics and kinetics in gait. With the increasing importance of evidence based practice and with the permanent development of subtractive manufacturing and introduction of additive manufacturing, there is a growing need for quantification of orthoses parameters. We describe a measurement method and protocol to quantify different parameters of a foot orthosis.

TECHNIQUE

A texture analyser is used to impose a displacement of the surface of the orthosis, while the applied force is measured. The measured points are determined based on the location of anatomical landmarks on the foot. Out of the measured data, parameters are calculated representing the stiffness, compression set and shape.

DISCUSSION

To illustrate the proposed technique, five different parameters are extracted from three example orthoses. Results show the added value of the proposed technique as the parameters are not only defined by the material but also by the shape.

The effects of custom-made foot orthosis using the Central Stabilizer Element on foot pain

BACKGROUND

Foot orthoses have been applied for the management of lower limb disorders, mainly for those who develop foot pain. The Central Stabilizer Element (CSE) is a new element that contains the midfoot laterally when a plantar insole is manufactured.

OBJECTIVES

To determine the effect on foot pain of adding the Central Stabilizer Element during the manufacturing process of foot orthosis, and to describe the proportions of Central Stabilizer Element in terms of width and length of this element.

STUDY DESIGN

A clinical study.

METHODS

A sample comprising 130 patients (57 males and 73 females) with foot pain was recruited for this study, with the patients having supinated, neutral, pronated and overpronated feet. All the patients received a custom-made foot orthosis with the Central Stabilizer Element. The Central Stabilizer Element was made of resins of polyvinyl chloride, and is a device insert in foot orthosis that contains the midfoot laterally to control pronation and supination movements. Perceived patient's foot pain was collected using a Visual Analog Scale at baseline, 15, 60 and 90 days after treatment.

RESULTS

A statistically significant decrease was found after foot orthosis application at all times in all foot types. There was a statistically significant correlation between all the ratio proportions according to foot posture (Foot Posture Index scores), except for heel length proportion.

CONCLUSIONS

The Central Stabilizer Element, applied at midfoot level of a custom-made foot orthoses through a directly mould technique, can reduce foot pain, when a previous foot posture status is considered.

CLINICAL RELEVANCE

The Central Stabilizer Element can be of interest for those professionals who are involved in the manufacturing process of foot orthosis, throughout the control of an excesive pronated or a supinated foot condition that is provoking foot pain.