Kanatli 2016.

Study characteristics
Methods	Randomised controlled two‐arm parallel trial
Participants	45 children, gender (33 boys, 12 girls) ‐ with moderate flexible flatfoot Age: mean age 39.5 months (17 to 72 months) Location: Ankara, Turkey Setting: Gazi University School of Medicine Inclusion criteria: moderate flexible flatfoot (Volpe classification ‐ Jack's test, standing heel position) Exclusion criteria: rigid flatfoot, neuromuscular disorders, genetic disease associated with collagen abnormalities Baseline characteristics: sample sex ratio 33 M: 12 F, not stated/group
Interventions	1. orthopaedic shoes, N = 21 2. control group, N = 24
Outcomes	Baseline and at follow up, i.e. 34.6 (10.9) months (range 24 to 57 months) ‐ Joint laxity (Wynne‐Davis method) ‐ Arch Index (Staheli method) ‐ x‐ray angles (lateral and AP talo‐1st metatarsal, lateral talo‐horizontal, lateral calcaneal pitch, lateral and AP talo‐calcaneal)
Source of funding	not stated
Notes	Orthopaedic shoes had internal ‘orthosis’ and Thomas heels
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Systematic, non‐random approach. ‘Patients were randomised and separated in two groups. Randomization was made by weekly basis. Patients that fulfilled the inclusion criteria during even number weeks consisted group 1 and in odd number weeks consisted group 2.’
Allocation concealment (selection bias)	High risk	Inexplicably unconcealed procedure: allocated depending on week odd or even week at enrolment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Children were not blinded. Children received orthopaedic shoes or no intervention. Personnel fitted the orthopaedic shoes or no intervention.
Blinding of outcome assessment (detection bias) ‐ self‐reported outcomes (e.g., pain, function)	Unclear risk	N/A
Blinding of outcome assessment (detection bias) ‐ objective outcomes	Unclear risk	It is not clear who assessed the outcomes and if this person was aware of group allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All enrolled children completed the study.
Selective reporting (reporting bias)	High risk	Arch index scores were not reported for any time point.
Other bias	Unclear risk	It was not clear how the orthopaedic shoes in this study were funded.