The diabetic foot requires more care than a healthy foot, and therefore, the properties of footwear adapted to the functional needs of the diabetic patient are stricter than in conventional footwear. The diabetic user should choose footwear that helps him to prevent complications caused by his disease, thus avoiding the risk of developing related pathologies.
When producing diabetic footwear, the following favourable practices should be prioritised:
Reduction of overpressure. There is a need for footwear without high pressure peaks in localised areas, both in the sole and in the entire volume of the foot in order to avoid discomfort, rubbing, wounds, etc. Upper materials should not produce rigid folds in flexion areas or discomfort in mobility areas of the foot such as the back of the heel, lining and insoles. In addition, materials for the inside of footwear, such as the lining and insoles, should not feel rough to the touch, nor have seams or abrupt edges to avoid friction. In order to avoid discomfort without affecting the rigidity of the entire shoe, the combination of sole and insole materials should provide sufficient insulation from uneven ground.
Comfort understood as more than "the absence of pain and discomfort" should be prioritised as the main property of diabetic footwear. This is a property that is difficult to quantify because it is a matter of user perception and, therefore, subjective assessments are analysed. In addition, a number of properties that can be affected by one another have to be averaged, making it difficult to prioritise each of them individually. Therefore, it is necessary to use specific techniques and methodologies of footwear analysis in order to quantify in an overall and objective way the comfortable performance of the footwear.
KEY ELEMENTS OF DIABETIC FOOTWEAR
In the absence of standards for the evaluation of comfort and functionality of footwear, various procedures have been developed, validated and implemented in the market in order to guarantee these types of properties in an objective way. INESCOP, as a footwear technology centre, awards the COMFORT and FUNCTIONAL labels to the footwear models which comply with a series of internal requirements. This also enables the manufacturer to optimise the most sensitive parameters for the improvement of the user's comfort and, therefore, to guarantee a healthy foot.
The COMFORT LABEL ensures the comfort of shoes through an assessment according to:
1. APPARENT COMFORT. Footwear analysis of comfort during use, as well as qualitative identification of footwear materials and components.
2. CHARACTERISATION OF PHYSICAL PROPERTIES. Footwear properties related to comfort are determined, such as: hardness, rigidity, sweat management, shock/ energy absorption, slip resistance and antistatic properties.
3. DIMENSIONAL CONTROL. All pairs in a batch are measured and weighted in order to control the grading process and homogeneity in production.
4. WEAR SIMULATION. Analysis of user perceptions through a skilled and controlled tester panel. Wear trials are adapted to the specific requirements of users and the intended use of the footwear under assessment.
FUNCTIONAL ASSESSMENT PROTOCOL
The FUNCTIONAL LABEL ensures that shoes are healthy and comfortable according to their intended use through an assessment according to:
1. APPARENT COMFORT. Footwear analysis in relation to aspects associated with comfort during use, as well as qualitative identification of footwear materials and components.
2. WEAR SIMULATION. Analysis of user perceptions through a skilled and controlled tester panel. Wear trials are adapted to the specific requirements of users and the intended use of the footwear under assessment.
3. THERMAL COMFORT. Assessment of the thermal response of footwear and feet during use and description of the thermal management to interpret certain properties, such as breathability, thermal insulation and thermal regulation.
4. FOOTSTEP ANALYSIS. Analysis of pressure distribution, which allows the interpretation of certain aspects, such as comfort perception, grip, stability and force distribution
5. MUSCLE ACTIVITY ANALYSIS. Assessment of the muscle activity required for waling and the user’s perception of muscle fatigue.
6. MOTION ANALYSIS. Gait analysis in order to know whether footwear restricts or enhances the movement of joints, whether it favours stability and dampens the impacts generated while walking, and even footwear grip on different floorings.