Users’ needs and expectations and the design of a new custom-made indoor footwear solution for people with diabetes at risk of foot ulceration

Figures & data

Table 1. Requirements for custom-made indoor footwear.

Key requirement
Peak plantar pressure is comparable to regular custom-made footwear
Other requirements
Easy donning and doffing
Lighter in weight than regular custom-made footwear
Regulating heat and breathable
Appearance satisfactory for indoor use
More comfortable than regular custom-made footwear
Safe to use
Good durability
No, or minimal, increase of shear forces compared to regular custom-made footwear
To be worn alternately with regular custom-made footwear
Improves adherence to indoor footwear use
Cheaper to produce than regular custom-made footwear

Table 2. Usability characteristics of participants’ regular custom-made footwear and expected presence or absence thereof in custom-made indoor footwear.

Negative usability characteristics	Not or hardly present	No opinion	Present or very much present
Regular custom-made footwear
Skin irritation	66 (33)	16 (8)	18 (9)
Ulceration	82 (41)	12 (6)	6 (3)
Sweating	82 (41)	16 (8)	2 (1)
Cold feet	72 (36)	10 (5)	18 (9)
Too much weight	46 (23)	32 (16)	22 (11)
Difficulty donning and doffing	48 (24)	30 (15)	22 (11)
Fit (too tight)	70 (35)	26 (13)	4 (2)
Custom-made indoor footwear
Ulceration	88 (44)	10 (5)	2 (1)
Inadequate fit	84 (42)	14 (7)	2 (1)
Skin irritation	74 (37)	24 (12)	2 (1)
Difficulty donning and doffing	74 (37)	18 (9)	8 (4)
Too much weight	70 (35)	28 (14)	2 (1)
Sweating	66 (33)	34 (17)	–
Cold feet	60 (30)	34 (17)	6 (3)
Positive usability characteristics
Good durability	–	22 (11)	78 (39)
Easy maintenance	–	34 (17)	66 (33)
Appealing appearance	6 (3)	64 (32)	30 (15)

Data expressed as % (n) of responders.

Table 3. Importance of usability characteristics of custom-made indoor footwear.

	Important or very important	No opinion	Not or hardly important	Item ranked as #1 priority
Prevention of ulceration	100 (50)	0	0	54 (27)
Prevention of skin irritation	96 (48)	4 (2)	0	25 (12)
Good fit	96 (48)	4 (2)	0	6 (3)
Easy donning and doffing	92 (46)	4 (2)	4 (2)	4 (2)
Flexibility of the material	86 (43)	14 (7)	0	4 (2)
Prevention of cold feet	70 (35)	26 (13)	4 (2)	4 (2)
Weight	74 (37)	20 (10)	6 (3)	2 (1)
Durability	78 (39)	16 (8)	6 (3)	–
Maintenance	70 (35)	28 (14)	2 (1)	–
Appearance	42 (21)	40 (20)	18 (9)	–
Prevention of sweating	40 (20)	50 (25)	10 (5)	–

Data expressed as % (n) of responders. One responder did not answer the priority question.

Figure 1. Schematic drawing with features and two images of the two types of custom-made indoor footwear design (see Table 4 for explanation of the numbers and material details).

Table 4. Features of the indoor footwear design.

Feature	Specification
(1) Vamp	Type A: Alcantara^® (4 mm microfiber); type B: felt (tweed extra 953)
(2) Toe part	Type A: leather; type B: no toe part
(3) Heel cap	Leather
(4) Upperpart	A combination of leather, Velcro fastener and a zipper. The Velcro fastener was used for optimal fitting and allows individual adjustment, with two fixations on both the lateral and medial side. The zipper had a metal ring to support opening and closure.
(5) Collar	Type A: leather with 8 mm sponge inside; type B: no collar.
(6) Contrefort	Thermoplastic reinforcement material (Rhenoflex^® 1.2 mm or Teefe^® 15).
(7) Protective welt	A: none. B: leather
(8) Heel	Wedged ethylene vinyl acetate, shore 60. Heel height was similar to the regular custom-made footwear. Heel rounding was similar to regular custom-made footwear.
(9) Outsole	Ethylene vinyl acetate, 4–6 mm, shore 40, to enhance foot progression and create more stiffness.
Rocker profile	The pivot point and angle of the pivot point were identical to the regular custom-made footwear. Adjustment was permitted, dependent on the insole type that is used (a more flexible insole might need more rocker profile).
Insole	The insole was identical to the insole of the regular custom-made footwear and made on the same shoe last. A 2.2 mm-thick full-length rigid insole was added under the normal insole for additional stiffness (Redoma^® Texon T97^®).
Height	Ankle-high (i.e., approximately 2–5 cm above the ankle).
Stitching	40/3 (Gunze count)

Table 5. Peak plantar pressures of the indoor and regular footwear per anatomical region.

Foot region	Indoor footwear^a	Regular custom-made footwear^a	Median difference^a,b	p Value^c	PP > 200 kPa Indoor footwear^d	PP > 200 kPa Regular custom-made footwear^d
Right foot
Hallux	162 (26–254)	156 (63–213)	–2 (–70 to 115)	0.594	2	2
Digits 2–3	109 (43–153)	114 (69–194)	–6 (–41 to 20)	0.110	0	0
Digits 4–5	99 (41–134)	78 (54–161)	–5 (–27 to 46)	0.953	0	0
Metatarsal 1	140 (38–257)	163 (63–257)	–22 (–33 to 5)	0.049	2	3
Metatarsal 2–3	193 (56–260)	189 (74–280)	–17 (–63 to 30)	0.025^c	2	4
Metatarsal 4–5	114 (44–187)	108 (66–198)	0 (–27 to 46)	0.314	0	0
Midfoot	89 (62–135)	102 (71–133)	0 (–31 to 6)	0.889	0	0
Heel	197 (93–239)	214 (110–313)	–10 (–105 to 16)	0.249	4	5
Left foot
Hallux	106 (60–398)	104 (63–514)	1 (–122 to 30)	0.678	1	3
Digits 2–3	112 (63–209)	99 (53–223)	21 (–61 to 87)	0.260	1	1
Digits 4–5	87 (76–260)	98 (54–209)	0 (–21 to 51)	0.575	1	1
Metatarsal 1	126 (71–232)	157 (63–226)	–3 (–49 to 30)	0.678	2	2
Metatarsal 2–3	147 (100–245)	155 (74–283)	1 (–66 to 27)	0.678	2	2
Metatarsal 4–5	130 (95–260)	135 (71–215)	2 (–29 to 45)	0.859	1	1
Midfoot	132 (99–165)	132 (75–174)	4 (–68 to 39)	0.343	0	0
Heel	176 (124–274)	193 (110–271)	3 (–69 to 38)	0.859	3	4

PP: peak pressure.

^a Data expressed as median (range) peak pressure, in kPa.

^b Difference is peak pressure in indoor footwear minus custom-made footwear; a negative score means lower pressures in the indoor footwear.

^c Cut-off for p values to be considered statistically significant was corrected for multiple testing with the Holm–Bonferroni method; with the smallest p value (p = 0.025) being larger than its corrected cut-off (alpha/16 = 0.05/16 = 0.003125), all differences are considered statistically not significant.

^d Data expressed as n.

Data availability statement

Data can be made available upon reasonable request.