The Effect of Insoles in Plantar Fasciitis

Plantar fasciitis is a common cause of plantar heel pain that may limit weight-bearing activities and reduce foot-related function. Custom-made insoles are frequently used in conservative management; however, direct evidence comparing orthoses produced using different materials and manufacturing methods remains limited.

This study was designed as an exploratory, parallel-group, randomized active-comparator trial. Forty-one participants with plantar fasciitis were randomly allocated to receive either a custom-made ethylene-vinyl acetate (EVA) insole manufactured using computer numerical control (CNC) milling or a custom-made thermoplastic polyurethane (TPU) insole manufactured using fused deposition modelling (FDM) three-dimensional printing. Participants were assessed at baseline and after 12 weeks of orthosis use.

The primary objective was to compare the effects of the two orthosis types on static plantar loading characteristics and gastrocnemius muscle activation. Static plantar loading was evaluated using pedobarography. Surface electromyography was used to record the activity of the bilateral gastrocnemius medialis and lateralis muscles during a standardized 10-metre walking task. Electromyographic measurements were normalized to maximum voluntary contraction recordings obtained during standardized plantar-flexion and dorsiflexion tasks. The 10-metre walk was used as the standardized task during which electromyographic data were collected and was not evaluated as a walking-performance outcome.

Secondary assessments included pain intensity, pressure pain threshold, foot-related function and participant satisfaction with the assigned orthosis. Pain intensity was evaluated under different symptom-provoking conditions, including first-step morning pain, pain during palpation and pain associated with prolonged standing.

Because both groups received custom-made insole as active interventions and the study did not include a sham, usual-care or untreated control group, the trial was designed to compare the two orthosis types rather than to determine the absolute efficacy of insoles. Accordingly, the findings were intended to describe between-group differences between CNC-milled EVA and FDM 3D-printed TPU insoles over the 12-week follow-up period.

Inclusion criteria

• Aged between 18 and 65 years
• Clinical diagnosis of plantar fasciitis by a specialist physician
• Clinical indication or prescription for custom-made foot orthoses
• Plantar fasciitis symptoms lasting for at least 3 months
• Heel pain localized to the plantar-medial calcaneal tubercle
• First-step pain in the morning or pain during the first steps after a period of rest
• Roles and Maudsley score of 3 or 4 at the baseline assessment
• Ability and willingness to provide written informed consent and comply with the study procedures

Exclusion criteria

• Body mass index greater than 30 kg/m²
• Presence of a clinically relevant cardiopulmonary, dermatological, neurological or musculoskeletal condition other than plantar fasciitis that could affect walking, plantar loading, pain assessment or participation in the study
• History of foot or ankle surgery
• Requirement for a walking assistive device during the study assessments
• Inability or unwillingness to wear footwear compatible with the assigned foot orthoses
• Cognitive or psychiatric condition that could prevent understanding of the study instructions, provision of informed consent or completion of the assessments
• Pregnancy