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Table 4 Studies using in-shoe testing to investigate the effects flat foot orthoses materials have on plantar pressures during waking

From: Effect of different orthotic materials on plantar pressures: a systematic review

Author, date Study design/participants/ sample size Equipment/protocol Plantar pressure variables of interest Type of foot orthosis/insole and materials tested Main findings
Healy et al., 2012 [6] Laboratory-based study with repeated measures design.
‘Healthy’ participants with mean (SD) age 30.9 (12.4) years, weight 69.3 (12.2) kg and height 172.0 (9.4) cm.
N = 10 (4 males and 6 females).
F-Scan™ in-shoe system (Tekscan, Boston, USA)
Sampling rate 100 Hz.
Walking speed: “participants walked on a treadmill at a self-selected speed”, walking speed was then maintained across the subsequent testing conditions.
Participants wore ‘standardised plimsoll shoes (a minimalist athletic shoe with a canvas upper and rubber sole).’
Peak pressure (kPa), peak force (N/BW), pressure-time integral (kPa.s) and average contact area (cm2). Conditions: (i) a shoe alone condition (i.e. control), (ii) 3 mm flat insole of low density polyurethane (Shore A hardness 20–25), (iii) 3 mm flat insole of medium density polyurethane (Shore A hardness 55 ± 3), (iv) 3 mm flat insole of low density EVA (Shore A hardness 25), and (v) 3 mm flat insole of medium density EVA (Shore A hardness 50). Compared to a shoe alone condition, medium density polyurethane insole materials provided significant reductions in peak pressure (kPa) in the first metatarsal region (p < 0.05; 215.7 ± 69.8 kPa vs. 180.0 ± 67.2 kPa), as did both the medium and low density polyurethane as well as low density EVA at the lateral metatarsals (p < 0.05; 352.5 ± 77.4 kPa vs. 288.0 ± 62.9 kPa, 292.2 ± 51.6 kPa and 295.7 ± 54.8 kPa, respectively). Low and medium density polyurethane materials were most effective at increasing contact area (cm2) and reducing pressure time integral (kPa.s).
McCormick et al., 2013 [15] Laboratory-based study with repeated measures design.
Participants with mean (SD) age 25.1 (9.63) years, weight 68.2 (13.8) kg and height 1.70 (0.11) m.
N = 30 (7 males and 23 females).
Pedar® in-shoe system (Novel GmbH, Munich, Germany)
Sampling rate 50 Hz.
Walking speed controlled.
Participants walked on a walkway in ‘standardised thin cotton socks’ and their most commonly used footwear.’
Peak pressure (kPa), maximum force (%BW) and contact area (cm2). Conditions: (i) a shoe alone condition (i.e. control), (ii) customised polypropylene foot orthosis, (iii) contoured polyethylene sham foot orthosis, (iv) contoured EVA sham foot orthosis, and (v) flat 3 mm EVA sham foot orthosis. Compared to a shoe alone condition, a flat 3 mm EVA material with a vinyl top cover significantly reduced peak pressures (kPa) at both the medial and lateral heel, mean difference significant at the 0.05 level (Bonferroni adjusted).
Rao et al., 2009 [16] Laboratory-based study with repeated measures design.
Participants with midfoot arthritis, mean (SD), range; age 63 (6), 55–78 years and body mass index 29.7 (5.1), 19.9–38.1 kg/m2.
N = 20 (all participants were female).
Pedar® in-shoe system (Novel Inc., St Paul, MN)
Sampling rate 90 Hz.
Walking speed controlled.
Participants walked over an undescribed surface in ‘subjects’ own footwear.’
Average pressure (kPa), contact time (% stance) and contact area (cm2). Conditions: (i) a shoe alone condition (i.e. control), (ii) shoe with custom moulded ¾ length shoe insert, and (iii) shoe with flat full length insert made of carbon graphite, semi rigid with an average thickness of 1.6 mm. Compared to a shoe alone condition, a 1.6 mm flat carbon graphite insole provided reductions in average pressure (kPa), contact time (% stance) and contact area (cm2) in the medial midfoot and in contact time (% stance) and contact area (cm2) at the lateral midfoot.
Rogers et al., 2006 [17] Laboratory-based study with repeated measures design.
Participants with mean age 25 years, mean weight 70.3 kg and mean height 1.73 m.
N = 9 (2 males and 7 females).
F-Scan™ in-shoe system (Tekscan Inc., Boston, USA) Sampling rate not reported.
Control of walking speed: not reported, so likely not controlled.
Participants walked on a walkway in undescribed footwear other than it being ‘subjects’ shoes.’
Peak pressure (kPa) and force-time integral (N.s). Conditions: (i) a shoe alone condition (i.e. control), (ii) flat 6.4 mm thick PORON® insole, and (iii) combination flat 6.4 mm insole consisting of a 3.2 mm Plastazote® top-layer and a 3.2 mm PORON® bottom-layer. Compared to a shoe alone condition, forefoot peak pressure (kPa) was significantly lower when using a 6.4 mm PORON® insole and a 6.4 mm PORON®/Plastazote® composite insole (p < 0.05). No significant differences were found in the force-time integral between the shoe alone condition and the PORON® (p = 0.64) and the shoe alone condition and PORON®/Plastazote® combination insoles (p = 0.42).
Tong & Ng, 2010 [18] Laboratory-based study with repeated measures design.
‘Healthy’ participants with mean (2SD*) age 29 (3) years, weight 75.0 (3.7) kg and height 1.75 (0.04) m.
N = 5 (sex of participants not stated).
F-Scan™ in-shoe system (Tekscan Inc., Boston, USA) Sampling rate not reported.
Control of walking speed: not reported other than “…subjects were instructed to walk at their usual walking speed…”, so possibly not controlled.
Participants walked on a walkway in undescribed footwear other than it being ‘subjects’ sports shoes.’
Minimum, maximum and peak pressures (kPa). Conditions: (i) a shoe alone condition (i.e. control), (ii) 6.2 mm Slow Recovery PORON® (extra soft) flat insole, (iii) 6.2 mm PORON® (soft) flat insole, (iv) 6.2 mm PORON® (soft) and firm Plastazote® flat insole, and (v) 6.2 mm PORON® (soft) and soft Plastazote® flat insole. Compared to a shoe alone condition, a 6.2 mm PORON® and firm Plastazote® combination insole provided significant difference for mean peak contact pressure (kPa) (p < 0.03; 60.7 ± 11.3 kPa vs. 47.9 ± 8.4 kPa) which accounted for an approximate 27% mean pressure reduction (whole foot).
  1. Notes: The most relevant information and data from the studies have been provided, N.s newton-second, kPa kilopascal, N/BW newton-body weight, EVA ethyl vinyl acetate, kPa.s kilopascal-second, %BW percentage of body weight, *authors reported 2SD