Wenger 1989.

Study characteristics
Methods	Randomised controlled four‐arm parallel trial
Participants	131 children recruited, with 129 meeting the criteria, 98 provided final outcome data Age: 1 to 6 years; mean age at baseline 29.3 (13.6) months (N = 98) Gender: N = 129, not reported; final N = 98 ‐ male 60, female 38 Location: USA, Dallas Setting: Dept Orthopedic surgery, Children’s Hospital, San Diego Inclusion criteria: 1 to 6 years old and flexible flat feet (observed to have valgus heel and poor arch formation in stance, further assessed by tip toe test, where varus shift of heel used to confirm flexible flat foot) Exclusion criteria: neurological condition (cerebral palsy or muscular disease), excessive laxity (Down or Ehlers‐Danlos syndrome), or previous treatment with foot orthoses or corrective footwear Baseline characteristics: (CFO group had more younger children (12 to 32 months), fewer in 32 to 52 month age range, fewer at 52 to 72 months age. Shoe group had lowest joint laxity, heel cup group had highest laxity, sex ratio ‐ not reported.
Interventions	Gp 1 ‐ controls Gp 2 – corrective orthopaedic shoes Gp 3 – Helfet heel cups Gp 4 – custom moulded plastic inserts (UCBL)
Outcomes	‐ x‐rays (lateral talo‐horizontal angle > 35°, lateral talo‐1st metatarsal > 10°, AP talo‐calcaneal ‐ too difficult to interpret) ‐ photos (all x‐rays and photos recorded every 6 months) ‐ foot progression angle of gait (intoe/straight/out‐toe), heel cord ‐ assessed by passive ankle dorsiflexion, laxity (rated on Wynne‐Davies 1 to 5 scale; low laxity = 0 or 1, high laxity = 2 to 5) ‐ examined every 3 months by flatfoot team (nurse, Orthop Surg, Pedorthist) in unspecified manner. Shoe fit checked every 3 months by pedorthist, and shoes replaced whenever required for correct fitting. Commenced N = 129, completed N = 98 (lost n = 31, over 3 years of trial) Group 1, 31 controls; 21 completed, lost 10 Group 2, 32 shoes; 28 completed, lost 4 Group 3, 35 Helfet; 27 completed, lost 8 Group 4, 31 UCBL; 22 completed, lost 9
Source of funding	shoes were provided
Notes	All participants wore specified footwear (some variation between groups) Minimum 3 years treatment and follow‐up Attrition 98/129 (76%), and at completion, boys = 61/98 (61%)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The patients were assigned to treatment groups by a nurse who picked numbers randomly.’ It is not clear how this was done.
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement of low risk or high risk.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants were aware of intervention group. Personnel were aware of intervention group.
Blinding of outcome assessment (detection bias) ‐ self‐reported outcomes (e.g., pain, function)	Low risk	‘At the time of three‐year follow‐up, clinical, radiographic, and photographic analyses were completed with the examiners in ignorance of the child’s treatment group.’
Blinding of outcome assessment (detection bias) ‐ objective outcomes	Unclear risk	31 participants were excluded from analysis as they were lost to follow up, mostly due to non‐compliance; the trialists did not report which treatment these exclusions received, and this may have biased the results of the study
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	98/129 completed the trial; 31/129 participants: ‘did not return for all of the follow‐up visits, did not wear the shoes regularly, or moved from the state and were dropped from the study’. Insufficient reporting of attrition/exclusions to permit judgement of low risk or high risk
Selective reporting (reporting bias)	Unclear risk	No reference to study protocol. Insufficient information to permit judgement of low risk or high risk
Other bias	Unclear risk	‘All shoes were provided by the Prescription Footwear Association’. No assurance was made of their independence from the research design, conduct, or report. However, since the report published negative findings, it suggests independence.