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Table 2 Characteristics of included studies

From: Evidence for foot orthoses for adults with flatfoot: a systematic review

Author/year/country Design Population Intervention Setting Outcomes/Measurement Main results
Acak 2020
Before-after study 34 participants (17 male) with pes planus complaints
Age: 18–28 years
Individually designed insoles:
1 mm thick stainless chrome steel covered with 3 mm thick antibacterial leather
Orthopedics and Traumatology Department of Turgut Ozal Medical Center in Inonu University Outcomes:
Height, weight, percent body fat, 30 m sprint test, vertical jump, 12 min Cooper test and Visual Analog Scale (VAS)
Image of the soles of feet were obtained by using the podoscope device.
Statistically significant differences found in pre- and post-test results in weight, BMI, 30 m run, vertical jump, 12 min Cooper run and VAS
Aminian et al. 2013
Repeated- measures intervention studies 12 participants (12 male) with flexible flatfoot
Age: 22.25 (±1.54)
Prefabricated orthosis: commercially available, full length and made of two layers: ethyl vinyl acetate at the bottom layer and 1 mm thick leather layer on the top.
Proprioceptive orthosis: made of rubber and covered by cloth, 2 mm thick insole with no arch support; 3 mm wedge as an elevation area extending from the navicular to the hallux and slopped medial to lateral.
No information Outcomes:
In-shoe plantar pressure (medial heel, lateral heel, medial midfoot, lateral midfoot, first ray, second and third rays, fourth and fifth rays)
Pedar-X system under 3 conditions (wearing the shoe only, wearing the shoe with prefabricated insole, wearing the shoe with proprioceptive insole)
Proprioceptive insoles: maximum force was significantly reduced in medial midfoot, and plantar pressure was significantly increased in the second and third rays compared to the shoe only condition.
Prefabricated insole: maximum force was significantly higher in midfoot area compared to the other conditions
Chen et al. 2010
Repeated- measures intervention studies 11 participants (6 male) with flatfoot
Age: 45.9 (±15.66)
Insoles: custom made of vinyl-acetate and 12 ± 3% far-infrared nanopowders
custom made of rubber and PU
No information Outcomes:
Spatio-temporal parameters, kinematic and kinetic data
eight-camera Eagle digital motion analysis system, using 15 spherical retro-reflective markers under three test conditions: walking barefoot, walking with shoes, and walking with shoes and insoles,
Walking with shoes and insoles and walking with shoes: increased the peak ankle dorsiflexion angle and moment, reduced the peak ankle plantarflexion angle and moment, increased the peak knee varus moment.
Effects of the orthoses on knee and hip were minimal and no significant differences were observed between walking with shoes and insoles and walking with shoes.
Han et al. 2019
(South Korea)
Repeated- measures intervention studies 28 participants (male college students) with flatfoot
Age: 20.29 (±0.46)
Weight: 70.43 (±4.15) kg
Height: 1.75 (±3.55) cm
Three different insoles:
The normal insoles were used as an experimental control without arch support function
Type A insole
With only arch support function
Type B insole
With both arch support and cushion pads for shock absorbing functions
Type A and B
Hardness and foot arch descent 45°
No information Outcomes:
Compute the range and peek of Rearfoot motion (RFM) and ankle joint
10 Vicon Motion Capture System was used. 21 reflective markers were attached with three different insoles
Insoles A and B show significantly less rearfoot ankle movement than the normal insole.
Jiang et al. 2021
Repeated- measures intervention studies 10 participations (8 male, 2 females
Age: 30 years with flexible flatfoot
Three different insoles:
Type A: the insole was obtained by 3D printing from the plantar pressure (PPRI)
Type B:
Orthotic insole
Type C
Flat insole
No Information Outcomes
Plantar pressure stance time, stride frequency and peak pressure in each area of the sole and plantar condistribution
Walking on treadmill at low, normal and fast speed with the different insoles
Force on the hindfoot and midfoot increased significantly when wearing flat insoles compared to PPRI and orthopedic insoles.
Contact area at slow and normal speed in the midfoot area is smaller when wearing PPRI than with flat insole
Kido et al. 2014
Repeated- measures intervention studies 8 participants (4 male, Age 29–38; 4 females, Age 26–38) with mild flatfoot deformity Accessory insoles
Therapeutic insoles: deformity: made using a CAD system (Pedcad Insole Designer; Pedcad, Oberkochen, Germany), designed to raise the medial longitudinal arch by 10 mm with a 5 mm inner wedge, particularly reducing the burden of the posterior tibial tendon
No information Outcomes:
tibia and the tarsal and metatarsal bones of the medial longitudinal arch (i.e., first metatarsal bone, cuneiforms, navicular, talus, and calcaneus)
Three-dimensional CT models; tibia and the tarsal and metatarsal bones of the medial longitudinal arch (i.e., first metatarsal bone, cuneiforms, navicular, talus, and calcaneus)
Therapeutic insoles: significantly suppressed the eversion of the talocalcaneal joint
The subjects voiced no complaints of discomfort
Miller et al. 1996
(United States of America)
Repeated- measures intervention studies 25 participants (13 male,12women) with asymptomatic pes planus
Age: 18–40 year
Orthotic device: constructed by using a plastic polymer and a firm Plastizote medial heel wedge No information Outcomes:
the dynamic GRFs (ground reaction forces) as a percentage of body weight in three directions-vertical, mediolateral, and anteroposterior-and the center of pressure by using an xand y-axis.
Walking across a standard force plate in 10 trials with and 10 trials without an orthotic device
Orthotic device: reduces vertical and anteroposterior GRFs in the early stages of the stance phase during the gait cycle.
No evidence was found to conclude that either the center of pressure or the mediolateral GRF showed any significant change when a standard street shoe was used with and without an orthotic device.
Murley et al. 2010
Repeated- measures intervention studies 30 subjects (15 male) with flatfeet
Age: 18–37 years
Customized FO:
a plaster cast impression was taken of each participant’s feet, made from a semi-rigid 4 mm polypropylene thermoplastic shell and included features considered to minimize rearfoot pronation
Modified prefabricated FO: three-quarter-length Formthotic made from dual-density polyethylene foam
No information Outcomes:
Comfort rating,
electromyographic activity, foot posture
VAS Scale (baseline and after 12 days), Electromyogram, X-rays, under 4 conditions: Four experimental conditions were assessed: (i) barefoot, (ii) shoe only, (iii) a heat-moulded (modified) prefabricated foot orthosis, and (iv) a 20-degree inverted-style customized foot orthosis.
Results show significant changes in EMG amplitudes of the tibialis anterior with both FOs, but only the prefabricated FO had a significant effect on EMG
Park et al. 2017
(Republic of Korea)
Repeated- measures intervention studies 15 participants (college students) with flatfoot Functional foot orthotic (FFO): customized for each individual’s foot shape and created with thermoplastic materials, high-density resistance elastic pad, cup sole for the plantar arch, low-elasticity pad for shock absorption in the heel, and ethylenevinylacetate (EVA) No information Outcomes:
change in the pelvic angle
six MX-F40 cameras, two OR6–7 force plates; walking on a previously fabricated Walkway before and after wearing the customized FFOs
Large changes in the pelvic angle on both the left and right sides during the pre-stance and mid-stance and pre-swing and midswing periods of the gait cycle before wearing the orthotic. These changes decreased significantly after wearing the orthotic (p = 0.05)
Peng et al. 2020
Repeated- measures intervention studies 15 participants
(9 male) with flatfoot
Prefabricated insoles:
3 cm thick medial arch support and 6 inclined medial forefoot posting, made of fabric with embedded cushioning silicon at the heel region
Running shoes (Reebok Run Supreme 4.0)
No information Outcomes:
hip, patellofemoral, ankle, medial and lateral tibiofemoral joint contact forces
3D-motion capture system, 4 force plates under two conditions: walking with shoes and foot orthoses and walking with shoes
Prefabricated insoles:
second peak patellofemoral contact force and the peak ankle contact force were significantly lower, significantly reduced the peak ankle eversion angle and ankle eversion moment, the peak knee adduction moment increased
Tang et al. 2015
Controlled- trial Intervention Group:
10 subjects (age 15–45) with flexible flatfoot
Control Group:
15 subjects (age-matched) without flatfoot
Total contact insole:
Custom-made, total foot contact with extended heel guard to keep subtalar joints in neutral position, forefoot medial posting, double-layer composition with superficial PPT and semi rigid plastozote base
No information Outcomes:
rearfoot motion and plantar pressure redistribution
motion analysis system under three test conditions (walk with barefoot, walk with sports shoes, and walk with TCIFMP and sports shoes)
Total contact insole: tends to reduce valgus angle and becomes statically similar to normal subjects, reduced foot pressure in the hallux and heel area compared to those wearing only sports shoe.
Xu et al. 2019
Randomized-controlled- trial Intervention Group:
40 subjects (20 males, 20 females) with flexible flatfoot
Age: 26–55
Weight: 63.37 (± 12.52) kg
Control Group:
40 subjects (20 males, 20 females) with flexible flatfoot
Age: 26–60 years
Weight: 67.18 (± 10.72) kg
Individually designed insoles
3 D print insoles with standardize shoes
Customized insoles
Standardize shoes with customized ethylene vinyl acetate (EVA) insoles
Norman Bethune Second Hospital of Jilin University Outcomes:
VAS was measured to measure comfort at 0 and 8 weeks
Footscan was used to measure plantar pressure under three test conditions: barefoot, with 3 D insole and standardized insole.
3 walking trials over a 10 m walking distance, at a speed of 3.12 (± 1.95) km/h.
The insoles were worn every day for 6–8 h over 8 weeks.
At week 0, peak pressures in the midfoot were significantly lower (p < 0.05) in the experimental group compared to the control group
At week 8, peak pressures in the midfoot were significantly higher (p = 0.05) in the experimental group compared to the control group
Comfort scores (measured anhnad by VAS) were significantly (p = 0.05) lower in the experimental group than in the control group