NCT04104555.

Study name	Orthotics for treatment of symptomatic flat feet in children ‐ the OSTRICH study
Methods
Participants	‐ Have pes planus secondary to any systematic condition or syndrome**, malignancy ‐ Have a history of foot or ankle surgery, or both ‐ Require an ankle‐foot orthoses, or other lower limb device, or have received treatment previously for their flat feet ‐ This does not exclude children with hypermobility spectrum disorder (HSD), where the manifestation is non‐syndromic and isolated (L‐HSD), peripheral (P‐HSD), or generalised hypermobility (G‐HSD)(14). OSTRICH pen and signposting to multimedia trial information SWAT inclusion criteria: any potential participant identified as eligible to be sent trial information will be eligible for the study OSTRICH birthday card SWAT inclusion criteria: all participants recruited into the host trial will be eligible to take part in this SWAT. Exclusion criteria: any participant who has withdrawn from the main OSTRICH study, or is not due a follow‐up questionnaire will be excluded.
Interventions	Other: Birthday card; Other: Birthday card plus nudge; Device: Prefabricated orthoses; Device: Custom orthoses; Other: Pen;Other: Signposting to multimedia; Other: Pen and signposting to multimedia; Other: Usual supportive care ‐ exercises and footwear advice (the comparator)
Outcomes	Physical domain subscale of the Oxford Ankle Foot Questionnaire for Children (OxAFQ‐C) over the 12‐month follow‐up period
Starting date	19 September 2019
Contact information	David Torgerson, PhD; Sarah Cockayne, MSc; sarah.cockayne@york.ac.uk clinicaltrials.gov/ct2/show/NCT04104555
Notes	University of York, UK