Effects of insoles adapted in flip-flop sandals in people with plantar fasciopathy: a randomized, double-blind clinical, controlled study

Objective: To evaluate the effects of insoles adapted into flip-flop sandals on pain and function in individuals with plantar fasciopathy (PF).

Design: Randomized, double-blind controlled study.

Setting: Physiotherapy clinic of the Faculty of Health Sciences of Trairi, Federal University of Rio Grande do Norte, Santa Cruz, Brazil.

Subjects: Sixty-six patients of both genders with PF were randomized into two groups: sandal insole group (SI; n = 34), which received a pair of custom flip-flop sandals with insoles covered with smooth synthetic leather; and plain sandal group (PS; n = 32), which received an identical pair of flip-flop sandals, but without the insoles.

Interventions: Patients were instructed to wear the flip-flops for 12 weeks for at least 4 hours/day.

Main measures: Pain (visual analogue scale-VAS) in the morning and at the end of the day were considered primary outcomes. Function (Foot Function Index-FFI and Foot and Ankle Ability Measure-FAAM) and functional capacity (6-minute walk test-6MWT) were considered secondary outcomes. The outcomes were evaluated at baseline and immediately after the intervention by a blind assessor.

Results: Between-group differences were observed in terms of morning pain (mean difference (MD) = -1.82 cm; 95% confidence interval (CI) = -3.3 to -0.3; P = 0.016) and function (MD = -0.10; 95% CI = -0.19 to -0.01; P = 0.023) after the interventions with the SI group showing superior improvements in comparison to the PS group.

Conclusion: The use of insoles adapted in flip-flop sandals for 12 weeks was effective at improving pain and function in individuals with PF.

Level of evidence: 1b.