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description
The Effectiveness of footwear, orthoses
and casted devices in redistributing plantar pressure: a systematic review of
the literature
Sharon Andrews
A dissertation submitted in partial requirement for the Bachelor of Science Degree (with Honours)
In podiatry 2004
Division of Podiatry Centre for Healthcare studies Faculty of Applied Sciences
University College, Northampton Word count: 11 618
Structured Abstract
Background
The need for the study
Podiatrists see patients with systemic and painful foot conditions and
provide preventative care and palliative relief. A range of materials, shoe
inserts, off-loading devices, therapeutic footwear and footwear adaptations
are available. To make the most effective choice appropriate measures of
effectiveness are required. Reducing plantar pressures is often the
objective. This review will consider pressure studies in two areas relevant
to podiatric practice: diabetes and painful foot conditions.
Diabetes
It is estimated that 2% of the UK population have Type I diabetes
(Hutchinson 2000). Studies from Australia, Finland, the UK and the USA
report the incidence of ulceration among people with diabetes as 2.5 –
10.7% and amputation rates as 1.8 -2.23%(Hunt and Gerstein 2003).
Footwear, orthoses and casts are important in the prevention and
treatment of diabetic foot problems.
The painful foot
10% of people may experience plantar heel pain (Crawford and Thomson
2004). Postema et al (1998) states that 83% of 459 subjects over the age
of 60 years of age had foot pain. A study of foot-shoe problems in the
2
Netherlands found that 60% of women and 30% of men suffered from
forefoot problems. Rheumatoid arthritis (RA)has a prevalence of 0.5-
1.5% in industrialized nations and in the UK of 36/100 000 in women and
14/100 000 in men (Suarez-Almazor and Foster 2001). Chalmers et al
(1999) reported that 90% of RA patients have foot problems.
Holmes and Timmerman (1990) refer to the 1989 AOFAS President’s
Symposium on The use and abuse of orthotics (sic)(no reference given)
which “concluded that the medical community lacked the objective data to
support the rational use of most orthotics (sic) prescribed to
patients”(p.144)
Objective
To assess research evidence that footwear, orthoses and casted devices
redistribute plantar pressures in the foot in a predictable fashion to allow
informed clinical prescription for foot pressure related problems
Search strategy
Searches of 24 databases, hand-searching of journals, interest groups,
manufacturers and following-up citations
Selection criteria
Types of study included: randomised controlled trials (RCTs) investigating
the quantitative effects of footwear, orthoses and casts in redistributing
plantar pressures at the foot-shoe interface during gait, in adults with
specific health problems. Qualitative measures will be included in studies
where the main focus is pressure measurement.
3
Data collection and analysis
Titles and abstracts were assessed for relevance against objectives,
inclusion and exclusion criteria. Full articles were checked again. Data
was extracted on the following:
1. how subjects were selected for inclusion/exclusion
2. the organisational setting(s) in which the trial took place
3. baseline sample population variables
4. description of the intervention(s) and numbers assigned to each
group
5. period/intervals of follow-up
6. methods/techniques of measurement
7. outcomes
8. findings/conclusions (based on Spencer 2000)
Parallel trials were assessed against quality standards for reporting
parallel randomised control trials (Moher 2001). Most of the included
studies were cross-over trials and were assessed against standards for
critical appraisal of quantitative studies (Griffiths, 2004)
Main Results
Seven RCT’s of mixed quality were identified. The included studies
demonstrated clinical, methodological and effects heterogeneity (Deeks et
al 2001). Pooling of results was, therefore, not possible and a qualitative
synthesis was undertaken.
4
Five studies considered the effectiveness of insoles/orthoses (one good,
two moderate, two poor). All concluded that insoles/orthoses were
effective at redistributing pressure, reducing pressure time integrals and
increasing contact areas. This was found in a variety of populations. The
case for custom-moulding over “off-the-shelf” shoe inserts was not
conclusive. Simple insoles had significant impact on pressure variables.
Moulded insoles were positively perceived by users compared with flat
inserts.
The evidence for footwear is too limited to draw conclusions. The quality
of the two studies was poor.
The DH pressure relief walker performed well in two studies compared
with total contact casts (TCC’s) but the areas examined differed ( forefoot
ulceration or heel pressure). The methodological quality of both papers
was poor.
A single study on the effect of a rocker bar on 42 individuals with primary
metatarsalgia found a reduction in force impulse and peak plantar
pressure over the metatarsals. The addition of insoles (ready-made and
custom-made) produced further off-loading. The quality of the study was
moderate but too limited to be conclusive.
5
Reviewer’s conclusions
Implications for practice
• There is evidence from a single centre RCT that simple cleron
insoles are an effective intervention for pressure reduction in low
risk diabetic patients and moulded inserts are appropriate for higher
risk patients without foot deformity. The insoles deteriorated
significantly over 6 months and should be replaced regularly.
• There is limited evidence from a small unique trial that rocker soles
reduce plantar pressure over the central metatarsals in women with
primary metatarsalgia.
• There is very limited evidence that visco-elastic heel pads reduce
heel pressure in a small unique trial of patients with treated heel
pain.
Implications for research
• Further multi-centre large scale RCTs are required to evaluate the
effectiveness and cost-effectiveness of therapeutic footwear,
orthoses and casted devices for the prevention and treatment of the
insensate and painful foot.
• the development of standard measures and research protocols is
urgently required to improve comparison of outcomes.
• Further research is needed to identify significant pressure variables
6
Acknowledgements
I would like to thank the following people for their assistance:
Mike Curran, Senior Lecturer ,Podiatry, UCN Dissertation supervisor, for
on-going help, enthusiasm and direction
Prof.Jackie Campbell, UCN , for her invaluable help with the statistics
Sue Griffiths, UCN for insight into the review process and help with the
quality assessment process
Alan Roslin and the library staff at the Park Campus Library, UCN for
excellent service and assistance in accessing the literature
Sarah Sutton Clinical librarian, University Hospitals Leicester for guidance
on the clinical application of EBM and getting started with on-line medical
literature searching
Sue Barnett, Foot pressure Interest Group (FIG) for the International
Protocol guidelines for Plantar Pressure Measurement
Ann Walsh, Ewan Kinnear and Rheema Draper for kindly proof-reading
and commenting on the text
Most of all, thank you to my husband, John, for coping with the last three
years with humour and equanimity.
Thanks also to Esther and Tom for successfully being very nice people
and my children at the same time
7
ABBREVIATIONS
AFO Ankle foot orthoses
ANOVA Analysis of variance
BMI Body Mass Index (weight in kilo/height in metres2)
DM Diabetes mellitus
FO Foot orthoses
FTI Force time integral
kPa kilopascal = 1000 pascals = 1 Newton per sq metre
MTPJ Metatarsal-phalangeal joint
N Newton
PCT Primary care trust
PPP Peak plantar pressure
PTI Pressure time integral
PWB Prefabricated walking boot
RA Rheumatoid arthritis
RCT Randomized controlled trial
RCW Removable cast walker
s seconds
RCB Removable cast walker
RRB Rigid rocker bottom
TCC Total contact cast
VAS Visual Analogue Scale
VPT Vibration perception threshold
8
Table of Contents
Page
Abstract 1 Acknowledgements 7 Abbreviations 8 Background 10
Review of the literature 12
Search strategy 35
Inclusion and exclusion criteria 36
Methodology 41
Data extraction 42
Characteristics of included studies 43
Ranking of studies 54
Results 61
Discussion 66
Reviewer’s conclusions 69
References 71
Bibliography 79
Appendices 92
9
Background
Mechanical therapy and footwear advice are central to the podiatrist’s
workload. For successful treatment, it is important to make the most
effective choice from the options available and to know what measures
are appropriate to assess effectiveness. Off-loading is the aim of
mechanical therapy in diabetes and for painful foot conditions.
Diabetes
It is estimated that 2% of the UK population have Type I diabetes
(Hutchinson 2000). Studies from Australia, Finland, the UK and the USA
report the incidence of ulceration among diabetics as 2.5 – 10.7% and
amputation rates as 1.8 -2.23%(Hunt and Gerstein 2003). Lavery et al
(2003), in a two year study of 1666 individuals with diabetes, found that
15.8% presented with or developed an ulcer.
Clinical guidelines (NICE 2004) on the prevention and management of foot
problems in Type 2 diabetes made five research recommendations, three
of which are relevant to this study:
4.1 therapeutic footwear should be evaluated for effectiveness and
cost effectiveness in patients at higher risk of ulceration
4.3 further research is required to identify the appropriate level and
combination of risk factors at which patients should be categorised
as at high risk for ulceration
10
4.5 the use of standardised measures … in research studies would
greatly enhance the ability of reviewers to undertake better
analysis, including comparison of outcomes of interventions (NICE,
2004 p.12)
Foot ulceration is preceded by peripheral vascular disease, neuropathy
and repetitive trauma (Kastenbauer et al 1998). Loss of protective pain
perception and proprioception produces abnormal foot loading, followed
by tissue damage and ulceration (Spencer 2003
Footwear adaptations and pressure-relieving devices are recommended
throughout the National Guideline for diabetic foot care (Hutchinson 2000,
NICE 2004) and the National Service Framework for diabetes
(Department of Health 2002. Research has suggested a threshold
pressure level predictive of ulceration. This review considers the evidence
that interventions off-load vulnerable areas.
The painful foot
Mechanical therapy is used to redistribute pressure away from painful
joints, to stabilise, to provide shock absorption or to accommodate foot
abnormalities (Pratt and Tollafield 1995). Corrective insoles are provided
which appear to correct foot position and improve patient comfort. Mueller
(1997) states that high pressures from orthoses, prosthetics or footwear
cause pain. Indirect measures are frequently used to assess whether
pressure redistribution is occurring (e.g. visual analogue (VAS) pain
11
scores or patient compliance). This approach relies on assumptions about
pathogenesis and treatment which may be incorrect. This review
considers the quantitative research available to support the underlying
principle that orthoses “work “ by redistributing dynamic pressure
An overview of research is offered below.
Review of the literature
Systematic Reviews
A systematic review of off-loading devices for diabetic foot problems found
limited evidence that orthoses were more effective than callus removal in
preventing ulcers. Limited evidence existed regarding the effectiveness of
two types of orthotic devices. The evidence for therapeutic shoes was
very limited. There was very limited evidence for TCCs as effective
treatments for diabetic foot ulcers. Quantitative measures used for
assessment were indirect i.e. actual plantar pressure is not measured.
Outcome measures included re-ulceration rates, healing rates and healing
times (Spencer 2000).
TTCs, pneumatic and removable cast walkers (RCWs) were
recommended to off-load ulcers in a cost-effectiveness review (Sinacore
1996). Reviewers critiquing this study noted that the choice of
comparators was not justified, the definitions of a healed ulcer varied
between studies and the included studies were equally weighted despite
differences in quality (NHS CRD 1998).
12
A systematic review of interventions for treating plantar heel pain included
heel pads and orthoses. Outcome measures tended to be VAS pain
scales. Due to the small scale of the included studies and poor
methodological quality, there was little evidence to support treatment over
no treatment in any intervention. (Crawford and Thomson 2003)
No current systematic review of the literature considers the effect of
footwear and orthoses on dynamic in-shoe plantar pressures.
Literature reviews
Landorf and Keenan(1998) evaluated foot orthoses (FO’s) by outcomes
such as patient satisfaction, pain and deformity, and plantar pressure.
They noted that “most reasoning for their (FO’s) use is anecdotal, with a
lack of scientific evidence to support the claims many practitioners make”
(p105). Footwear is not included in their review. Inclusion criteria and
quality assessment is not provided.
A critical review by Pratt (2000) quality assessed published articles about
FOs. Accepted trials treated foot and shoe as “a basic functional unit”
(p399). The search strategy was not described. Only 40 references of low
quality were identified and these were not critiqued.
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Choice of in-shoe pressure measurement devices
A number of systems are available to measure foot function (Landorf and
Keenan 1998). Some measure static rather than dynamic pressures or
measure barefoot forces. Cavanagh and Ulbrecht (1994) provide an
overview of the rationale and methodology of clinical plantar pressure
measurement. Those systems requiring individuals to strike a pressure
sensitive plate present difficulties for people with mobility problems and/or
poor eyesight. Gait may be altered as subjects target the force plate.
(Rose et al, 1992). The value of a single barefoot footfall is questionable
when considering the effect of shoes or FO’s or the influence of shoe wear
on pressure distribution (Alexander et al 1990). Dynamic pressure
distribution demonstrates “at risk” areas for plantar ulceration in diabetic
individuals better than static ones. (Alexander et al 1990)
Pressure readings from floor-mounted transducers cannot be directly
compared with in-shoe transducers because of differences in sampling
speed and sensor resolution.
Pressure is derived from force. Transducers estimate force by “measuring
the deformation caused by an unknown force on a material with known
force/deformation properties” (Cavanagh and Ulbrecht 1994 p.125). The
dynamic forces occurring during walking have three components: vertical,
anterio-posterior shear and medio-lateral shear. No commercially
available in-shoe systems measures shear forces.
14
Measurement systems should be assessed for suitability. (Roy 1988,
Rosenbaum and Becker 1997; Barnett 1998) Sampling rate and sensor
resolution are more important in dynamic than in static systems.
Measurement technology should provide data that is accurate,
reproducible and repeatable with a high degree of reliability and durability,
minimum variability and at an affordable cost. Specific technical
problems include hysteresis, creep and linearity. These can be adjusted
for if a consistent pattern can be identified. Environmental factors, such
as temperature and humidity, are a particular problem in the shoe (Finch
1999). The quality of calibration by the manufacturer and carried out in
the research or clinical environment is essential to good quality recording.
(Nicolopoulis et al 2000). Resch et al (1997) describe the problems found
by frail elderly patients, standing on one leg to calibrate a sensor.
Measurement technology
In-shoe systems dominating the literature are matrix systems: F-scan
(Tekscan,Inc. South Boston, MA) and the EMED system (Novel GMBH,
Munich, Germany). No study using F-Scan met inclusion criteria for this
review. One included study used the Parotec system ( Paramed,
Germany ).
Emed
EMED (Novel GMBH, Munich, Germany) is a range of instruments for
recording and evaluating static and dynamic pressure distribution on flat
and curved surfaces. EMED Pedar is an in-shoe pressure analysis tool
15
based on capacitance. Finch (1999) describes capacitance technology as
two conducting wires, separated by an insulating layer, which vary in
distance according to pressure. Emed Mikro (or Micro) is a portable
version. Pedarmobile dispenses with the cable linking subject to data
collection computer, removing the need for gait-altering turns.
According to Graf (1993) capacitance measurements allow shear forces to
be compensated for without changing sensor characteristics. Emed Pedar
enables bi-lateral in-shoe pressure analysis, recording static and dynamic
real time measurement. Described by Graf as “highly accurate”, the
flexible 2mm insoles have around 85 sensors with a resolution of one
sensor/cm2. Adult versions come in standard shoe sizes which are not cut
to fit. Sampling frequency is variable. Data is collected in an infinite loop
and the last 1000 pictures stored. This equates to about 17 seconds (s)
walking time. Kernozek, La Mott and Dancisak (1996), Rozema et al
(1996) and Barnett (2002) demonstrated reasonable reliability in bench
and dynamic tests.
Finch (1999) notes that insole systems may affect the coefficient of friction
between the foot and the shoe, but Lavery et al (1997b) states that EMED
insoles do not affect gait. Sampling frequencies can be increased to
100Hz but as frequencies increase the proportion of sensors sampled
decreases to maintain a sampling rate of 990 sensors per second. Thus,
high frequencies result in low resolution. The flexibility of the insoles
16
allows good conformity but on curved surfaces vertical forces (which are
converted to pressure readings) become vector forces(non-perpendicular).
EMED has a lower threshold of 20kPa to reduce noise during recording
but loads of less than this magnitude occur during parts of the gait cycle.
In a comparison of Emed Pedar with a Kistler Force plate, pressures were
consistently 3% lower on Emed for this reason. (Barnett 2002)
Kernozek , La Mott and Dancizak (1996) state that the key to
measurement with sensors is the ability to calibrate each sensor. This is
possible with the Pedar and Parotec systems. Calibration is via a
patented air bladder pressure device.
Parotec
Parotec (Paromed, Munich) is an insole system based on 24 conductive
transducers embedded in 2.5 mm PVC. Each transducer is embedded in
a hydrocell with a resolution of 2.5kPa and a range of 600kPa. The
transducer consists of a membrane on a mounting ring, which bends a
silicone beam when deflected by applied pressure. The deflected beam
alters resistance in the transducer producing a measurable deviation in
the current. Each sensor is positioned at a point of peak pressure as
identified from 350 subjects. The insoles are calibrated by the
manufacturer and are reported to have a measurement error of less than
+/- 2.5%. (House et al 2002)
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The sensors cover 46% of the insole surface. The software stores
pressure data at a rate of 250Hz for five complete gait cycles, ignoring the
first steps. (Hsi, Lai, Yang 1999). As with Pedarmobile, there are no
cables connecting the insole to the data-collecting computer. A rapid
sampling rate improves the system’s suitability for measuring pressures
during running. Bauer, Cauraugh and Tillman (1997) found that Parotec
provided stable and consistent values across six postural variables.
Chesnin, Besser and Selby-Silverstein (n.d.) found no discernable drift,
negligible hysteresis, temperature drift, humidity drift or non-linearity over
a range of bench tests. In a study supported by the manufacturer, they
compared output from Parotec with a force system and found correlation
coefficients in the good to excellent range. Different insole sizes are
available with the sensors placed in the correct relative position for each
size.
The system requires an acceptance of pre-determined points of peak
pressure, which may not be appropriate for subjects with deformity or
abnormality. When assessing the effect of FOs, the relative position of the
sensors may also be changed.
Comparing results from different studies
Inter- and intra- sensor variability, differences in calibration, sensor
resolution and sampling speeds make quantitative comparisons between
pressure studies inadvisable and results should be used qualitatively.
Shear stress cannot be measured and this is significant in many
18
pathologies. The system chosen should be appropriate to the study design
and population (Dhalla, Johnson and Engsberg 2003, Hartsell, Fellner and
Saltzmann 2001, Lavery, 1997a).
The Foot Pressure Interest Group (FIG) produced draft protocol guidelines
for plantar pressure measurement (Barnett 1998) to encourage
comparability between studies. Regarding in-shoe systems,
recommendations were made in a variety of areas (See appendix 1). As
the protocol follows recommendations in the wider literature it has been
referred to when assessing methodological quality.
Measurement variables
In-shoe devices measure magnitudinal, temporal and spatial variable in all
or part of the foot (Harrison and Hillard n.d.). Force is mass x acceleration
and is measured in Newtons (N). Pressure is the distribution of force over
an area. The SI unit is kilo Pascals (kPa) but Nm-2 is frequently used in
the literature. (Rosenbaum and Becker 1997) Applied force is composed
of vertical force (the effect of gravity or ground reaction force) and shear
forces (friction). Vertical forces are usually the larger component. Forces
are individual but consistent if measured on consecutive days or after
several months. Time parameters are more consistent than force
parameters (Roy 1988).
More research is required to identify the most useful variable in research
or clinical practice.(Hodge et al 1997, Lavery et al 2003, Pitei et al 2000,
19
Barnett 1998). Definitions/formulae are not consistent (Harrison and
Hillard n.d.). Mean peak plantar pressure (PPP) is the maximum pressure
detected by each sensor during the stance phase of gait and is described
in kPa or N/cm2 (Stess, Jensen and Mirmiran 1997).
Pressure-time integral (PTI) is peak pressure multiplied by duration of
weight-bearing in seconds. (Stess, Jensen and Mirmiran 1997). This
variable includes loading time and is a better indicator of the pressure
sustained during each gait cycle.
Walking speed data is important in trials where subjects self-select a
comfortable pace. Zhu, H. et al (1995) demonstrated that gait speed has
significant effects on plantar pressures. A self-selected pace better
reflects normal walking style (Barnett 1998) but walking speed data
should be collected and measurements rejected when velocity deviates by
more than 10% from the average.
Pressure variables and the diabetic foot
PPP became significant when linked with ulceration in the diabetic foot
(Boulton et al 1983, Boulton et al 1985, Veves et al 1992, Lavery et al
1998). The possibility of a threshold for ulceration was investigated
(Stess, Jensen and Mirmiran 1997, Frykberg et al 1998, Mueller 1999,
Lavery et al 2003) but it is now recognized that ulceration is the result of
the interplay between pressure, time and contact area and the permissive
effects of neuropathy (Masson et al 1989). A case control study of 225
20
age-matched patients evaluated risk factors for ulceration (Lavery et al
1998). PPP>65N/cm2, history of amputation, foot deformities and
neuropathy were significantly associated with ulceration. Stacpoole-Shea,
Shea and Lavery (1999) in a study of 36 subjects found a combination of
PPP and PTI were predictive of ulceration. Sensitivity was 83% and
specificity was 69%. A prospective study over 3.5 years of 187 type 2
diabetic patients with a history of ulceration analysed risk factors (
Kastenbauer et al 2001). Elevated vibration perception threshold (VPT),
increased PPP and daily alcohol intake were significant predictors.
Raised VPT was the strongest predictor (relative risk = 25.4). A 2-year
study of 1 666 diabetic patients evaluated dynamic PPP as a screen for
ulceration (Lavery et al 2003). PPP alone was insufficient as a diagnostic
tool for high-risk. Strong correlations were found between elevated
pressure and foot deformity and with callus. Stess, Jensen and Mirmiran
(1997) measured PPP, PTI and force-time integral (FTI) over three areas
of the forefoot in 97 diabetic patients. All pressure variables were raised
but individual variables were not discussed. Barnett (2002) found that PTI
was most influenced by diabetes and could be the most important variable
to alter with footwear and orthotic interventions.
Research has identified strong links between plantar callus, raised PPP
and ulceration. Wrobel et al (2003) in a cross-sectional study of 152 men
with diabetes found that callus increased PPP by up to 29%. In a small
group study, callus removal was found to reduce PPP by 25-32% (Pitei,
21
Foster and Edmonds 1999). Callus should be removed before assessing
the affect of interventions on PPP (Barnett 1998)
Pressure variables and the painful foot
Metatarsalgia in rheumatoid arthritis is presumed to be due to excessive
pressure to the metatarsal heads (Hodge, Bach and Carter 1999). In a
study of 12 people with RA and a history of forefoot pain, PPP were
assessed and patients asked to complete a VAS pain score whilst wearing
prefabricated or custom-made EVA insoles (with/without metatarsal
dome). Standing and walking pain were highly correlated suggesting that
repetitive pressures were less significant than in the insensate foot.
Pressure was distributed more uniformly with orthoses and both types
significantly reduced average pressure. Custom-moulding with dome
significantly reduced walking and standing pain and was preferred by most
subjects. Pain and peak pressure were not correlated but pain and
average pressure were. This correlation accounted for only 32% of the
variance. It should be noted that the authors pooled the results from 20
out of 24 feet and the sample size was small. Postema et al (1998)
similarly found no correlation between pain scores and peak pressures in
a study of 42 patients with primary metatarsalgia.
Types of intervention
Total Contact Cast (TCC)
A TCC is a close-fitting, below knee cast which protects neuropathic lower
limbs and promotes healing of ulcers whilst allowing the patient to remain
22
mobile. (Sinacore1996). TCC’s had a 91% healing rate and led to
substantial improvements in healing times compared with in-hospital care
and daily wound dressing. Casting requires highly skilled people to make,
renew and replace on a regular basis. Complications include superficial
abrasions (27%) and fungal infections (15%). With undiagnosed
osteomyelitis, casting can lead to more serious complications (Sinacore
1996). A Cochrane review of pressure-relieving interventions for diabetic
foot ulcers found a single poor quality RCT testing TCC’s (Spencer 2000).
This does not mean that they are not effective but that more and better
research is required.
Beiser et al (1991) investigated pressure variations in different cast
designs and subjects were asked about comfort and ease of walking.
Short leg casts (with/ without cast shoe) had greatest overall performance.
Short leg casts with walking heel were most efficient at reducing peak
pressures but awkward to wear. Pressures decreased as immobilization
moved up the leg. PPP at the first metatarsophalangeal joint (MTPJ) in 20
asymptotic subjects was compared in athletic shoes (baseline condition),
two types of post-operative shoes (one with a 1st MTPJ cut-out) and a
fibre-glass short-leg walking cast. The cast and shoe with cut-out
significantly reduced pressure (Corbett et al 1993). Zhu et al (1995)
postulated that TCC’s decelerate gait. TCC’s have little padding,
reducing compression, preventing shear within the cast.
23
Rubber bottom cast boots, conventional short leg casts and TCC’s were
assessed for PPP in 10 healthy volunteers (Conti et al 1996). A significant
reduction in forefoot pressure was found in both types of cast. Average
weight-bearing area was significantly increased in the TCC, reducing
forefoot pressures. Normal gait patterns are bi-phasic with pressure
peaks at heel strike and toe-off. With casts, the force curves were bell-
shaped due to a flat-footed gait and restricted ankle movement. Subjects
were not tested in normal footwear. In normal subjects, casts reduce
forefoot and rearfoot loading, redistributing them to the mid-foot.
Total contact casts with terminal devices
Cast boots and heels were added to TCCs and compared with therapeutic
shoes (Lavery et al 1997a). For hallux and 1st MTPJ ulcers the devices
were equally effective. TCC plus cast heel was more effective for 2nd-5th
MTPJ ulcers. Casts were superior to therapeutic shoes and baseline
footwear. Dhalla, Johnson and Engsbert (2003) added cast shoes and
heels to TCCs. 28 healthy volunteers were assessed with six
interventions: athletic shoe (control), TCC and TCC with four different
terminal devices. For the forefoot, TCC with conventional cast or rigid
rockers were best and would be indicated for fore-foot ulcers. All devices
reduced midfoot pressure by at least 40%. In the rear-foot, PPP was
significantly reduced in all configurations excluding the rigid rocker heel.
This suggests that TCCs can be augmented.
24
Removable cast walkers compared with TCCs
1. Asymptotic subjects
The advantages of prefabricated walking boots (PWB) are: time of
application, lightweight construction, relative low cost, provision of
consistent and continuous pressure to off-load and minimize shear forces,
ease of wound monitoring and hygiene (Hartsell, Fellner and Saltzman
2001). It was hypothesized that TCC and PWB would significantly and
similarly reduce PPP compared with running shoes. 9 healthy volunteers
were assessed. A 3/8” open-cell urethane foam insole was added to the
PWB. Compared with running shoes, TCC’s and the modified PWB
significantly reduced pressure across the forefoot with an insignificant
increase at the mid-foot. The impact of shear stresses, patient
compliance, differences between healthy and symptomatic patients and
activity levels were not addressed.
Aircast pneumatic walkers were equally good or better at reducing PPP
than TCC’s in a small sample of 12 healthy volunteers(Baumhauer 1997).
In 18 healthy subjects, the Bledsoe Diabetic Conformer Boot was found to
reduce PPP as well as a fibre-glass TCC( Pollo et al 2003)
2. In diabetes
In a study of 25 diabetic neuropathic subjects, the effectiveness of TCC’s,
therapeutic shoes and removable walking casts (DH pressure relief
walker, Aircast pneumatic walkers, Three D dura-steppers and CAM
walkers were compared. The DH pressure relief walker which did not
25
vary significantly from the TCC in reducing PPP over forefoot ulcers.
Lavery et al (1996)
Boulton and Armstrong (2004) suggest that the failure of RCWs in clinical
practice is because patients remove them. “Instant” TCC’s made from a
RCW made unremovable with the application of plaster or cohesive
bandage are proposed as a solution.
Footwear
1.In diabetes
Perry et al (1995) compared plantar pressures in 39 subjects barefoot,
wearing leather-soled oxford-style shoes and in inexpensive running
shoes. (Diabetes and neuropathy n= 13, diabeties without neuropathy n=
13, healthy controls, n=13). The oxford style shoes did not reduce
pressures from barefoot levels. Running shoes reduced pressure
significantly at the heel and forefoot. It was concluded that individuals with
insensate feet should not wear leather-soled shoes and the running shoes
are a useful alternative for individuals with sensory loss and without foot
deformity.
Pitei et al (1996) (abstract only available) measured in-shoe pressures for
22 diabetic patients in three types of footwear – patients’ own shoes,
surgical shoes with an EVA-moulded insole and standard trainers. When
newly fitted, the insoles significantly reduced plantar pressures compared
26
with patients’ own shoes. When worn in (duration not given) pressures
were further reduced. Trainers were less effective at pressure reduction.
Plantar pressures were assessed in 49 diabetic neuropathic patients (no
existing or previous ulceration, n=19; existing or previous ulcers, n=30)
(Resch et al 1997). PPP and PTI were assessed in patients’ own
comfortable walking shoes, own shoe with Frelens custom-moulded semi-
rigid insoles, jogging shoe with and without insoles and an orthopaedic
shoe with metatarsal bar and insole. The high degree of variability of the
F-Scan device (25-30% accuracy) made it impossible to draw any
conclusions. The orthopaedic shoes tended to increase pressures and
were found uncomfortable and awkward by patients. This study did not
claim significant improvements from the interventions, possibly because
the baseline was a good quality walking shoe.
Kastenbauer et al (1998) compared specially designed running shoes with
a custom-made insole in an “in-depth” shoe. Running shoes were as
effective in reducing pressures at the central metatarsals in a sample of 13
diabetic patients
2. Diabetes and amputation
30 patients with diabetes and trans-metatarsal amputations had PPP
measured at the distal residuum and the contra-lateral forefoot in six types
of footwear; full-length shoe with toe-filler (baseline) and combinations of
27
total contact insert, ankle foot orthoses (AFO), rigid rocker bottom sole
(RRB) or short shoe. All conditions except the short shoe reduced PPP
on the residuum. The full shoe with insert and RRB had few complaints
from patients. The addition of an AFO reduced pressure but patients had
functional problems. (Mueller, Strube and Allen1997)
Insoles/Orthoses
1.Asymptotic subjects
Windle, Gregory and Dixon (1999) used Parotec to assess the shock
attenuation characteristics of visco-elastic, polymetric foam, Saran
(military issue) and Sorbothane insoles in military boots during running
and marching compared to a “no insole” baseline. 11 military recruits
were trialled. All insoles significantly reduced PPP at heel strike and
forefoot loading. The Sorbothane insole was significantly more effective
than the other insoles. House et al (2002) demonstrated that 100 – 130
km of running on visco-elastic or polyurethane insoles did not reduce
shock absorption. Foam insoles were more effective than visco-elastic
and did not degrade. The most effective version reduced heel PPP by
37% and forefoot PPP by 24%.
Novick et al (1993) studied the effect of three types of rigid orthoses on
PPP in 10 subjects to identify whether FO’s were effective for off-loading
sites of ulceration in diabetic individuals. Interventions were 1/8” Spenco,
two rigid Sorbotholen custom-made insoles, one with 3/8” relief under the
1st MTPJ, the other without. Least pressure at the 1st MTPJ was recorded
28
with the relief orthoses, the greatest with the plain rigid version, followed
by simple Spenco insoles. Mid-foot and heel pressures were minimised
with the Spenco insole, but increased with both rigid orthoses.
Brown, Rudicel and Esquenazi (1996) tested PPP in 10 subjects wearing
off-the-shelf and customized orthoses in standard extra depth shoes.
Plastizote, cork and plastic insoles reduced pressures at the forefoot, heel
and 2nd-5th MTPJ, but increased pressures at the mid-foot.
2.In diabetes
A small-scale study investigated the impact of flat and moulded
customized inserts on PPP under the MTPJ’s of 12 diabetic patients,
some with neuropathy. (Lord and Hosein (994) Testing the hypothesis that
moulded inserts would be more effective than flat, the authors suggested
that this occurred by redistributing load to the midfoot and by cushioning.
Results were treated with caution because of problems with the pressure
measurement system (F-Scan). Ashry et al (1997) considered the
effectiveness of three different insoles in reducing plantar pressure in a
sample of 11 diabetics with amputation of the hallux. A base-line reading
in standard extra-depth shoes was compared with the same shoes with
customized 6 mm plastizote insoles with and without the addition of a
metatarsal pad, arch pad or both on the amputated and non-amputated
foot. Mean peak pressure was significantly reduced across the forefoot,
lesser toes and heel in both groups but there was no significant difference
between interventions.
29
Lobmann et al (2001) compared the effects of a mixed materials moulded
orthosis (14 mm thick) on plantar pressure in 81 type 2 diabetics with no
history of ulceration. 18 subjects were considered at risk of ulceration
because of high plantar pressures and these received insoles. 63
subjects acted as the control group and wore conventional footwear.
Using pedobarograph, a reduction of 30% was found in maximum peak
pressure of the whole foot in the “at risk” group. Pressures gradually
increased during the following 12 months sush that a 13% improvement
over baseline measures remained after one year. The control group
increased pressures over the year and there was no significant difference
between the two groups at the end of the study. This demonstrates the
importance of considering insole degradation.
Frykeberg et al (2002) considered the effect of a rocker insole on forefoot
pressures on 25 subjects (with and without diabetes) wearing their own
footwear, standard post-surgical boots and the boot with a rocker insole.
The insole produced a reduction in PPP of greater than 40% over the
baseline or the surgical boot alone.
3. The painful foot
McLauchlan et al (1994) used a discrete sensor system (GaitScan) to
compare treatments for metatarsalgia: a felt U-shaped pad and metatarsal
dome. 30 asymptotic patients were investigated. The dome produced a
significant reduction in pressure over 1st – 4th MTPJs compared with
30
baseline values. Poon and Love (1997) study of a metatarsal dome on
plantar pressures and pain in 14 patients with metatarsalgia found that
mean pressure was reduced by 13% at the forefoot. The VAS revealed a
71% reduction in pain scores and 11 subjects found some or marked
improvement of symptoms.
Kelly and Winson’s (1998) assessment of commercially available insoles
compared Viscoped with Langer in 33 patients with primary lesser
metatarsalgia. Langer performed better objectively and subjectively.
Hodge, Bach and Carter (1999) completed a repeated measures pressure
assessment of a variety of orthoses in a group of 12 subjects with
rheumatoid arthritis with foot involvement and pain at the 2nd MTPJ. A
“shoe only” baseline, pre-fabricated and custom-made orthoses of similar
materials, density and size were assessed. The custom-made orthoses
were also tested with the addition of pre-formed metatarsal bars and
domes. Qualitative assessment was made by asking subjects to complete
a VAS Pain Scale, and express a preference for one of the interventions.
All orthoses significantly reduced pressure under the 1st and 2nd MTPJ but
the custom-moulded orthoses with metatarsal dome was the intervention
of choice. A correlation was found between average pressure and pain
but this only accounted for 32% of the variation leading the authors to
conclude that other factors were implicated in pain than PPP. Li et al
(2000) investigated the effect of orthoses on PPP in subjects with
rheumatoid arthritis (n=12) and an age-matched group of healthy subjects
31
(n=8). Moulded polyethylene orthoses reduced PPP and peak force
significantly for both groups, with greater pressure relief and redistribution
in RA patients.
External devices
Schaff and Cavanagh (1990) hypothesized that rocker-bottom shoes
might redistribute PPP in insensate feet. Healthy volunteers were tested
(all US men size 9, n=8)) wearing extra-depth shoes (control) with/without
rocker sole attached. PPP was reduced over the medial and middle MTPJ
(-30%) but increased at the heel, mid-foot and lateral forefoot (+20%).
Force impulse was significantly reduced at the metatarsals (53% medial,
35% control). It is difficult to generalize results as there is such diversity in
rocker bottom shoe modifications (Brown et al 2004) and diabetic patients
may respond differently.
Fuller, Schroeder and Edwards (2001) added rigid rocker bottoms to post-
operative shoes to assess the effect on pressures over the forefoot in 16
healthy females. PPP and FTI were significantly reduced compared with
the post-operative shoe alone.
Three types of rocker soles (toe-only, negative heel and double) were
studied for their effect on PPP in 40 healthy subjects (Brown et al 2004).
PPP, PTI and sensor contact time were compared with a baseline shoe. A
significant reduction was found at the forefoot in all versions. Pressure
was shifted to the mid-foot with the negative heel and toe-only rockers.
32
Summary of the literature
Plantar pressure studies are typified by small sample sizes and short-term
cross-over studies. Very few studies were randomised and the use of
asymptotic volunteers to test interventions for diabetic conditions is
common. Recruitment information is rarely given and ethical and informed
consent only occasionally reported. The general opinion of the research is
that footwear interventions and casts do reduce plantar pressure.
Study design and Statistical Considerations
Cross-over studies
Pressure measurement studies frequently use cross-over studies. This
refers to trials where each subject acts as their own physiological control
by being tested in all interventions. Sample size can be reduced, but
there are potential carry-over effects i.e. one intervention affects the
results of the next intervention. Williams designs account for carry-over
effects but these were not mentioned in trials reviewed above or in
included trials. (Qu, 2003)
Repeated measures
Repeated measures refer to the number of trial runs each subject has with
each intervention and the number of steps nested to find mean values.
Repeated measures reduce intra-patient variability and increase statistical
power. The degree of improvement is marginal and decreasing, therefore
the aim is to find the number of repeats which maximise power but
minimise data over-load. Increasing the number of follow-ups and/or
33
baseline measures from one to three or four, can reduce sample size by
35-70%, but there is little value in more the six or seven measures
(Kernozek, LaMott and Dancisak, 1996; Vickers 2003).
Sample size and data analysis choices
Sample size calculations were rarely offered in the literature. To calculate
sample size, the researcher needs to know (i) the effect size, (ii)
population standard deviation for continuous data (iii) desired power of the
experiment (β) (iv) significance level (α) . The last two are fixed by
convention (usually α = 0.05 and β = 0.8) but the former are unique to the
experiment. Effect size is determined by the investigator. The population
standard deviation is estimated by a pilot study. There was little evidence
of this kind of calculation. For parametric studies, a minimum sample size
of 30 is usually accepted (Pett, 1997)
An underlying normal variation is often assumed and statistical tests
chosen accordingly – particularly analysis of variance. Many are
underpowered and non-parametric tests would be more appropriate (Pett,
1997).
One subject, two feet
A further consideration is raised by Menz (2004) and relates to the use of
data from an individual subject or as two individual feet. Statistical
sampling has an underlying assumption that each observation is
independent (Pett 1997, Polgar and Thomas 2000). This does not apply
34
to a pair of feet. Including both feet doubles the sample size, which might
appear to make the evidence more powerful. The outcome of statistical
analysis is distorted, however, because the observations are not
independent. Menz (2003) recommends that the unit of analysis should
be people, not feet.
Search strategy
The following databases were searched:
1.Cochrane Library including databases of systematic reviews, abstracts
of effects (DARE), central register of controlled trials (CENTRAL),
methodology, health technology and NHS economic evaluation.
2. Clinical effectiveness databases: NICE (National Institute for Clinical
Effectiveness) technology appraisals and clinical guidelines, Research
findings register
3. General health sites: British Nursing Index, AMED, Medline, Embase,
Recal, CINAHL,PRODIGY
4. General databases: British Humanities Index, PsychInfo
5. Full-text electronic journals: Bandolier, BIOMED central, Clinical
Effectiveness, Infotrac, Emerald Fulltext, Highwire, ASSIAnet, Science
Direct, Swetswise, Web of Knowledge
6. ZETOC for tables of contents and conference proceedings
7. Index to theses
8. COPAC
9. Relevant journals were hand-searched.
10.Citations were followed up from relevant articles.
35
Inclusion and Exclusion criteria
Inclusion criteria
Study design
• Randomized control trials
Justification: Systematic reviews of non-RCT’s can compound the
problems of individually misleading trials and produce a lower quality of
evidence. Sackett et al (2000) advises avoiding systematic reviews which
include both levels of evidence unless these are analysed separately.
Types of participants
• Studies of patients with specific conditions where clear
inclusion criteria stated
• Adults
Justification: considering literature on effectiveness of interventions in a
broad spectrum as appropriate to podiatric clinical practice. Eligibility
criteria are necessary to establish where findings can be applied.
Findings with healthy individuals may not be transferable to the target
group. (Barnett 2002)
Outcome measures
• Quantitative plantar pressure measures
36
• Dynamic in-shoe measures.
• An appropriate base-line for comparison as required by study
design
• Adequate sample size
Justification: to test the hypotheses that footwear and orthoses are
effective because they redistribute pressure in real-life situations i.e.
dynamic, in-shoe. Cross-over studies require a smaller sample size than
parallel trials. Of the crossover trials only Hsi, Lai and Yang (1999) offered
a calculation of 22 subjects. For this reason, a minimum sample size of
20 was accepted for inclusion. The only parallel trial (Barnett, 2002) used
a power calculation and found a minimum sample of 47 was required for
the control and intervention groups. Type 1errors are more likely with
small samples. (Pett 1997)
Interventions
• Footwear
o Orthopaedic shoes
o Footwear adaptations for purposes of pressure
redistribution
o Specific types of shoe e.g. running shoes
• Orthoses
o Rigid
o Flexible
37
o Customized
o “Off-the-shelf”
• total contact casts
• surgical shoes/post-operative shoes
• walkers
• ankle-foot orthoses
Justification: these represent the range of interventions for redistributing
pressure regularly available in clinical practice. Combinations of
interventions were also accepted
Measuring devices
• systems which measure in-shoe dynamic plantar pressures
• systems which had been independently tested and
demonstrated to be reliable, accurate, repeatable.
• Thin, flexible, individually calibrated pressure sensors where
used
• systems based on array/matrices rather than a few discrete
sensors
Justification: Most individuals are ambulatory and wear footwear.
Systems should measure actual pressures between the foot and the
shoe/cast. Discrete systems have been shown to alter gait and identified
points of pressure may alter when orthoses/footwear are changed for
38
testing. The thickness of the transducers can cause alterations in gait.
Some insole measurement systems are thick and change the position and
movement of the foot. They can fill the shoe, leaving too little space for
the foot. Thick insoles do not mould to the foot or the orthoses being
assessed. Thin, flexible pressure sensitive insoles overcome many of
these problems. (Nicolopoulis 2002).
Exclusion criteria
Types of participants
• Healthy, asymptotic subjects
• Children
• Non-ambulatory
• Those using walking aids such as walking sticks or frames
Justification: walking aids alter pressures on the foot, change gait and
make dynamic testing difficult (Resch et al 1997). Subjects with systemic
conditions such as diabetes or with biomechanical abnormalities do not
have the same plantar pressure distributions and responses as asymptotic
subjects (Barnett 2002). Children have different plantar pressure
distributions from adults (Rosenbaum and Becker 1997)
Interventions
• Dressings
• Hosiery
39
• Strapping
Justification: These are included if one of a range of interventions. As
temporary interventions, it was decided to exclude them from the study.
Outcome measures
• Qualitative studies unless findings linked within studies with
a primarily quantitative focus e.g. pain questionnaire,
expressing a preference between interventions
• Pressures other than plantar pressures.
• Studies of other gait parameters e.g. timing, sequences,
stance pressure distributions, postural sway
• Studies which focus on barefoot or stance pressure
distributions
• centre of pressure, centre of force studies
Justification: this study is investigating the case that footwear and
orthoses redistribute pressure. Qualitative studies look at indirect
measures. Variables implicated in ulceration, pain and healing relate to
amount and length of pressure and contact area over which it is
distributed. Other variables are not directly related. Barefoot and stance
measures are excluded for reasons explained above. Centre of pressure
and force do not have consistent formulae for calculation and there is
some question of their value in clinical practice. (McPoil and Cornwall
1998; Barnett1998)
40
Measuring devices
• systems which measure barefoot pressures only
• static pressure measurement systems
• discrete sensor systems
• systems for which independent test data could not be found
• early prototypes which were demonstrably unreliable
Language/Date
• English language only
• Post-1990
Justification: The researcher did not have access to translation services
and is aware that this may introduce bias into the selection of data (Khan
and Kleijnen 2001.The technology required was developed from the early
1990’s onwards.
Methodology
Searching was undertaken between August 2003 – April 2004. The
search strategycwas constructed around the inclusion critieria. By
referring to indexed terms a large number of possible search terms were
collated and used to test the available literature (See Appendix 2). A
highly specific search strategy could not be devised. Searches were
sensitive, producing many references. For this reason a list of excluded
41
articles has not been provided although recommended by the Centre for
Disseminations and Reviews. (Glanville, 2001)
Titles and abstracts were assessed for relevance against the objectives of
the review, inclusion and exclusion criteria. Full articles were checked
again. Ideally, this process would be carried out by more than one
reviewer and conducted “blind” – i.e. unaware of authors’ identities. (Khan
and Kleijnen 2001) Because of the nature of this research, this has not
been possible and selection bias may be introduced as a result.
Data extraction
Data extraction is potentially subjective and open to bias. It would ideally
be completed with the reviewer “blinded”, that is, unaware of authorship.
A panel of reviewers to independently assess studies is an alternative
solution. Both options are unavailable in a single-authored dissertation. A
number of extraction protocols are available (Khan and Kleijnen 2001) but
relate to double blind parallel RCTs. In this study data was extracted on:
• how subjects were selected for inclusion/exclusion
• the organisational setting(s) in which the trial took place
• baseline population variables such as age and gender
• description of the intervention(s) and numbers assigned to
each group
• period and intervals of follow-up
• methods and techniques of measurement
• Outcomes
42
• findings and conclusions (based on Spencer 2000)
Characteristics of included studies
Study Armstrong (1999)
Methods Repeat measures, crossover design single centre RCT
Method of randomisation of treatments not described
Participants 25 consecutive diabetic patients with grade 1A (University of
Texas)((Oyibo et al n.d.) plantar forefoot ulcerations: existing
or recently healed single ulcers, peripheral neuropathy and a
diagnosis of DM.
Neuropathy established as loss of protection to 10g
monofiliament and biothesiometer
Interventions
Baseline: Reebok canvas sneaker
Total contact cast: method of Kominsky without plywood sole
Aircast pneumatic walker
DH pressure relief walker
Prescription-depth inlay shoes with PW Minor stock inlays
Outcomes PPP (N/cm2)
PTI (N.s/cm2)
43
Measured over heel
Measurement system
Emed pedar
Five trials, mid-gait steps, 40 steps per subject per modality
Allocation concealment
No
Notes High percentage of male participants (92%) Type I/ type II
not described. Treatment of participants not described. No
a priori sample size calculation. No discussion of informed
consent or ethical approval. Suitability of modalities for
patients with active ulceration not discussed. No review after
trial or follow-up to ensure no adverse effect. Did not appear
to be supported by industry. Masking not described.
Full citation
Armstrong, DG and Stacpoole-Shea, S (1999) Total contact
casts and removable cast walkers: mitigation of plantar heel
pressure Journal of the American Podiatric Medical
Association 89 (1) pp 50-53
Study Barnett (2002)
Method Prospective randomised clinical control trial
Single centre
44
Method of randomisation described
Baseline, three month and six month follow-up
Mixed methods
Participants 103 Type I and Type II diabetic individuals without major
vascular disease, foot deformity, mobility problems, existing
or previous ulceration
Control and intervention group matched demographically
and health characteristics except for age
Interventions
Control: 3 mm unadapted Cleron shoe inserts (n=52)
Intervention: polyurethane gel and EVA orthoses (off-the-
shelf)
(n=51)
Pressures measured in standard extra-depth orthopaedic
shoes. Inserts transferred to patients’ own footwear
between follow-ups
Outcomes PPP (kPa/cm2)
PTI (kPa.s/cm2)
Contact area
Pressure variables measured over 9 described masks and
the whole foot
Bristol Foot Health Questionnaire
45
Diary of wear
Measurement system
Emed pedarmobile
Allocation concealment
No
Notes Participants with DM recruited from City PCT podiatry
database. Intention to treat analysis included. Does not
appear to be supported by industry.
Full citation Barnett, S, (2002) The clinical effectiveness of orthoses
prescribed to control and reduce diabetic foot pathology
Ph.D Thesis, University of the West of England
Study Fleischli (1997)
Method Repeated measures crossover study
Single centre RCT
Method of randomisation of treatments not described
Participants 26 patients with existing or recently healed diabetic
neuropathic plantar forefoot ulcers. Analysed in two groups;
46
Forefoot (metatarsals) ulcers (n=19), Hallux ulcers
(n=7). Groups not matched. VPT assessed with
biothesiometer. Some participants do not meet generally
accepted criteria for neuropathy (VPT > 25)
Baseline demographic and health data given
Interventions
Baseline: rubber soled canvas sneaker
Total contact cast: method of Coleman, without plywood sole
DH pressure relief walker
Darco ortho-wedge shoe (also described as Darco half-
shoe)
Darco rigid-soled post-operative shoe
Accomodative felt and foam dressings
Outcomes PPP (Ncm-2)
Percentage change from baseline
Measured over sites of ulceration
Measurement system
Emed pedar
Allocation concealment
47
No
Notes Recruited from clinics at University health systems of an
American city. No sample size calculation. Ethical issues
not addressed. Masking not explained. No support from
industry reported.
Full citation Fleischli, JG et al (1997Comparison of strategies for
reducing pressure at the site of neuropathic ulcers Journal of
the American Podiatric Medical Association 87 (10) pp.466-
472
Study Hsi (1999)
Method Single centre RCT.
Method of randomisation of treatment order not described
Two-factor analysis of variance with interactions between
orthosis and subject. Repeated measures, cross-over
design
Participants 22 consecutive patients with treated unilateral heel pain
Interventions
Baseline: patients’ own shoes and hosiery
48
Visco-elastic heel orthoses
Outcomes PPP (kPa/cm2)
PTI
Foot to sensor contact time
Measured over whole foot
Measuring system
Parotec
Allocation concealment
No
Notes Did not appear to be supported by industry
Full citation Hsi, WL; Lai, JS and Yang, PY (1999) In-shoe pressure
measurements with a visco-elastic heel orthosis Archives of
physical medicine and rehabilitation 80 (7) pp 805-810
Study Lavery (1997b)
Method Repeated measures crossover study
Single centre RCT
Method of randomisation of treatment order not described
49
Participants 32 consecutive patients with DN and existing or recently
healted plantar forefoot ulcers. Method of establishing DM
or neuropathy not described
Stratified into three sub-groups: 1st MTPJ ulcers (n=10), 2nd
– 5th MTPJ ulcers (n=12), ulcers of hallux (n=12)
Interventions
Baseline: thin rubber-soled canvas oxford sneaker
Extra-depth shoes in men and women’s styles
New Balance cross-trainers in men and women’s styles
SAS Timeout (men) and Free-time (women) comfort shoes
Each assessed with and without plastazote/urethane insoles
Outcomes PPP (N/cm2) and percentage change from baseline over the
three sites of ulceration
Measurement system
Emed pedar
Allocation concealment
Yes
Notes Recruited from clinics at an American city university hospital.
No a priori sample size calculation. Patient characteristics of
50
sub-groups not given. Ethical issues not addressed.
Masking over ulcers not described. Does not appear to be
supported by industry.
Full citation Lavery, LA et al (1997b) Reducing plantar pressure in the
neuropathic foot: a comparison of footwear Diabetes Care
20 (11) pp 1706-1710
Study Postema (1998)
Method Repeated measures, cross-over design
Multi-centre double-blind RCT
Method of randomisation of treatment order described but
not justified
Mixed methods
Participants 42 patients with a history of primary metatarsalgia
41 female
Clear inclusion and exclusion criteria
Interventions
Baseline: same brand of extra depth shoe
51
Standard insole and custom-made insole of the same
materials. Standard insole not a commercial product but
made to standard pattern rather than customized.
Rocker bar
Pain questionnaire and patient preference
Outcomes PPP (N/cm2)
Force impulse (N s)
Pain scores from patients with pain
Preference ratings
Measurement system
Emed pedar
Allocation concealment
Yes
Notes Recruited from three areas of the Netherlands. No a priori
sample size calculation. Does not appear to be supported
by industry
Full citation
Postema, K et al (1998) Primary metatarsalgia: the influence
of a custom moulded insole and a rockerbar on plantar
52
pressure Prosthetics and orthotics international 22 (1) pp.35-
44
Study Redmond (2000)
Method Repeated measures crossover study
RCT – probably single centre
Treatment order randomised but method not described
Participants 22 subjects with excessive pronation (criteria given)
Interventions
Baseline: Dunlop Volley athletic shoe
Non-cast insole made of card with a 60 high density EVA
varus rear-foot post
Modified Root orthosis: 4mm high density polypropylene
shell, PVC cover, 60 extrinsic EVA varus rear-foot post
Outcomes Maximum force (N)
FTI (N.s)
PPP (kPa)
Maximum PPP(kPa/cm2)
PTI (kPa.s/cm2)
Contact area (cm2)
53
Measurement system
Emed pedar
Allocation concealment
No
Notes No subject demographic information. No recruitment
information. Ethical approval form University of Sydney. No
a priori sample size calculation. Non-casted orthosis is not
an appropriate treatment for abnormal pronation. Does not
appear supported by industry.
Full citation Redmond, A; Lumb, PS and Landorf, K. (2000) Effect of cast
and non-cast foot orthoses on plantar pressure and force
during gait Journal of the American Podiatric Medical
Association 90 (9) pp.441-449
Ranking of studies
Seven RCTs met inclusion criteria. Heterogeneity in every aspect of study
design prevents any pooling of data. Six cross-over studies were quality
assessed against standards produced by Griffiths(2004) (Appendix 3).
One parallel trial was assessed against the Consort standards (Moher,
Schulz and Altman 2001) for reporting of RCTs (Appendix 4). Trials were
ranked on the following:
54
1. How participants were allocated to interventions
2. provision of scientific background and rationale for the study
3. method should include how participants were chosen, settings
where data collected, precise details of the interventions, specific
aims and objectives, primary and secondary outcome measures,
how sample size was determined
4. randomisation: technique for allocation and blinding
5. statistical methods used for primary outcome comparisons
6. results: participant flow, protocol deviations, recruitment and follow-
up, baseline demographic data, numbers analysed, outcomes and
estimation, adverse events.
7. Discussion: should include interpretation of results considering
hypotheses, sources of bias or lack of precision, statistical
problems. Should also consider generalizability. (Moher, Schulz
and Altmann 2001; Griffiths 2004)
Study design of included trials
Methodological quality was generally poor particularly regarding sample
calculations and sizes, ethical considerations, data analysis and study
design. (See appendices 3,5 and 6). All except Barnett (2002) were
crossover studies. Barnett’s study took baseline measures with follow-ups
at three and six months. Postema et al (1998) allowed subjects to wear
each intervention for a month before in-shoe pressure measures were
taken and a new intervention fitted
55
Participants of included studies
Four studies involved diabetic patients involving 200 participants
(Armstrong 1999; Barnett 2002; Fleischli 1997; Lavery 1997b).
Barnett(2002) included patients with types I and II diabetes with no history
or existing ulceration or significant pathology. Armstrong (1999), Fleischli
(1997) and Lavery (1997) studied patients with existing or recently healed
single plantar diabetic ulcers but did not specify if patients were Type I or
Type II diabetes (DM).
Hsi (1999) selected patients with treated unilateral heel pain (n=22).
Postema (1998) chose patients with primary metatarsalgia. (n=42)
Redmond (2000) included asymptotic individuals with abnormal pronation
(n=22).
Interventions studied in included trials (Appendix 7)
Eighteen different interventions were tested, excluding baseline footwear.
TCCs, the DH pressure relief walker and the PW Minor extra depth shoe
were covered by more than one paper. The quality of the papers
examining these interventions (Fleischli 1999, Armstrong 1997 and
Lavery 1997) were poor. The methods of cast construction differed.
The Four subgroups of intervention were identified: TCC’s and RCW’s,
footwear, insoles/orthoses and external shoe adaptations.
56
Outcome measures (Appendices 8 and 9)
All included trials collected mean PPP. Trials used different sampling
speeds (50 – 100hz) and different “masks” i.e. areas of the foot. Studies
examining pressure over healed ulcers sites did not explain how this was
done. PTIs were collected by four studies
Mean contact area was collected in two studies (Barnett 2002 and
Redmond 2000). This data is relevant as pressure is dependent on the
available surface area for dispersion. Only Barnett (2002) and Hsi(1999)
collected walking speed data whilst all studies asked subjects to walk at
their own pace.
Two studies used a mixed methods approach. Barnett asked subjects to
complete a Foot Health questionnaire and to keep a diary of
orthoses/insole use. Postema et al asked subjects to complete a pain
questionnaire and asked for their preference between interventions
Methodological quality
Objectives of study
Study design, in some trials, did not match objectives. Armstrong (1999)
selected patients with fore-foot ulcers to consider the impact of off-loading
devices on heel pressures. Armstrong (1999) and Fleischli (1997)
considered ulcer treatment. The inclusion of patients with healed ulcers
57
was not jusitified. Walking speeds were not collected although speed has
a bearing on repetitive stresses which delay healing and on the validity of
the study (Zhu et al 1995). Lavery (1997b) considers ulcer prevention but
includes patients with existing ulcers in the sample population. Barnett
(2002) also studies interventions to prevent ulcers and, therefore,
excludes subjects with existing or previous u
ulceration.
Two studies examine the relationship between pain and plantar pressure
distribution. (Postema 1998; Hsi 1999). Hsi (1999) does not justify
recruiting subjects who do not have heel pain and have had treatments
which might affect results. One study investigated the use of functional
orthoses to change forces acting on abnormally pronated feet. (Redmond
2000)
Quality of studies
All the cross-over trials randomised their treatment order but did not
describe how this was done. Ethical considerations were poor. Some
papers did not mention informed consent, right to withdraw or consider the
advisability of testing ulcerated individuals in sneakers. Callus reduction
was only carried out by one researcher although callus increased plantar
pressures by up to 30%. Appendix 5 assesses trials against the foot
pressure measurement protocol. (Barnett 1998)
58
Statistical considerations (Appendix 6)
Sample sizes tended to be small (Armstrong, n=25; Fleischli, n=26; Hsi,
n=22; Redmond, n=22). Sample sizes were calculated in two studies (Hsi
1999 and Barnett 2002), but no justification given for assumptions
required for the calculations. Most studies presumed an underlying
parametric distribution apart from Barnett (2002)and Redmond (2000),
who tested their data. Redmond (2000) found that some data could not
be transformed to a normal distribution and used non-parametric tests
instead. High order crossovers studies require particular procedures to
calculate sample size and power determination to take into account
potential carry-over effects from different treatments (Qu, 2003). There
was no evidence of this in the affected studies.
Six studies used repeated measures. The number of steps per subject
per modality varied from 5 – 40. (Appendix 9). These are within guidelines
(Kernozec, La Mott and Dancisak 1996)
Four studies had less than thirty subjects in their sample. An adequate
sample is required to guard against type I errors i.e. optimistically
concluding a significant difference between intervention and control. Only
Barnett (2002) stated a clear hypothesis. All studies found significant
improvements on their chosen baseline, reflecting the findings of the
literature review. This may be evidence of a publication bias in English.
Only three studies offered a power calculation (Barnett, Hsi and
59
Redmond) to assess the risk of a type II error i.e. falsely accepting the null
hypothesis.
Non-parametric tests should be used for non-normal distributions. Most
included studies did not discuss data distribution. All studies used mean
and standard deviations as descriptive statistics without justification.
Medians and ranges should be used with non-parametric data (Pett,
1997). Two studies (Fleischli 1999 and Lavery 1997) sub-divide their
sample into small, uneven groups. Pett (1997) considers that unequal cell
sizes cause serious problems for the repeated measures designs and
multivariate ANOVA’s that these studies use.
Treatment of data from right and left feet (Menz 2003) varies betweem
included studies (Appendix 10). Fleischli and Lavery investigated
pressure over single ulcer sites. Postema selected the most painful foot.
If neither foot was more painful, the choice was randomised, but the
method was not given. Barnett collected readings from ten left and ten
right steps, but later figures appear pooled as do those of Hsi. Redmond
pools data after statistical testing and justifies this, doubling of the sample
size. Armstrong does not give any figures.
Results
Total contact casts and removable cast walkers
1.Fleischli (1997) studied the effect of pressure off-loading devices
over ulcer sites of 26 neuropathic diabetics, sub-divided into
60
subjects with ulcers under the metatarsals (n=19) and those under
the hallux (n=7). The DH pressure relief walker was equivalent to
the TCC at off-loading the hallucal ulcers (79%, 85% respectively)
and more effective for metatarsal ulcers (85%, 76%). Both devices
were significantly better than the Darco OrthoWedge shoe (66%
forefoot group, 64% hallux group) , accomodative felt and foam
dressings (48% forefoot group, 34% hallux group) and the Darco
rigid post-operative shoe (36%, 7% respectively). The authors
concluded that if pressure reduction is strongly correlated with
healing, the DH pressure relief walker is an acceptable alternative
to the TCC.
2.Armstrong (1999) investigated the impact of TCCs, Aircast
pneumatic walker, the DH pressure relief walker and extra-depth
therapeutic shoes on heel pressure in 25 diabetic neuropathic
subjects with plantar forefoot ulcers. The TCC was found to be
significantly better at reducing PPP. There was no significant
difference between removable casts. Extra-depth shoes offered the
least protection. Considering PTIs, the DH walker was significantly
better than other modalities. All interventions, including the
baseline sneakers, reduced PTI significantly more than therapeutic
shoes.
The DH pressure relief walker performed well compared with TCC’s but
the areas examined differed (area of forefoot ulceration or heel pressure).
61
The methodological quality of both papers is poor. Currently debate about
patient compliance (Boulton and Armstrong 2004) suggests that patients
remove walkers, impairing clinical outcomes. TCC’s may, therefore,
remain the intervention of choice.
Shoes
1. Lavery (1997b) considered three kinds of therapeutic footwear. For
individuals with metatarsal ulcers (n=22), comfort shoes were more
effective than cross-trainers and therapeutic shoes. For those with
hallucal ulcers (n=10), extra depth shoes were equivalent to
comfort shoes and significantly better than cross-trainers.
2. Armstrong (1999) examined heel pressures (PPP, PTI and foot
contact areas) in 25 diabetic patients with forefoot ulcers whilst
wearing TTCs, RCWs and extra-depth shoes. The latter were the
least effective intervention as PTI exceeded the baseline sneaker.
The evidence for footwear from these studies is insufficient to draw
conclusions regarding effectiveness. The quality of both studies was poor.
Insoles/orthoses
Terminology was not consistent – some authors described a moulded
device as an insole, others as an orthoses.
1. Hsi (1999) studied the effect of visco-elastic heel orthoses in 22
patients with treated heel pain whilst wearing their own shoes.
62
This intervention reduced mechanical load in the posterior heel
and midfoot and increased load over the first metatarsal and
hallux during gait.
2. Postema (1998) considered the effect of two types of insole and
a rocker bar on forefoot pressures in 42 patients from several
centres across The Netherlands with a history of primary
metatarsalgia. The custom-moulded insole reduced force
impulse by 10.1% and peak pressure by 18.25% over the
central forefoot. Lower pain scores were found in patients
experiencing pain whilst wearing the customized insole and
more users expressed a preference for this intervention.
3. Redmond (2000) tested the effect of a modified Root orthosis
and a flat, non-cast insole (both with 60 varus posting) on a
sample of 22 individuals with abnormal pronation. The Root
orthosis reduced pressures and forces at the heel and
increased heel surface area. Midfoot forces remained
unchanged as an increased load was offset by increased
contact area. Forefoot pressures were also reduced leading the
authors to conclude that foot function was altered profoundly
with the Root orthosis in healthy young adults with abnormal
pronation. The choice of non-Root comparator was
questionable: a card base with EVA varus rear-foot post. This is
not a typical alternative treatment for pronation and therefore a
poor indication of the relative benefits of the modified Root
intervention. Study quality was poor.
63
4. Barnett (2002) recruited 103 neuropathic diabetic patients who
were randomised to receive 3mm unadapted Cleron insoles or
off-the-shelf polyurethane and EVA moulded orthoses for six
months in their own footwear. Plantar pressures were assessed
at baseline, three and six months. Orthoses reduced PPP by
22%, PTI by 16% and increased mean contact areas by 11%.
The Cleron insoles (designed as a “blind” and for control
purposes) also reduced PPP (16%),and PTI (10%). Mean
contact area was increased by 2%. The author concluded that
Cleron insoles were successful at reducing pressure in
individuals with diabetes and neuropathy but without substantial
foot deformity. Pre-formed orthoses were suitable for patients
with higher planter pressure and increased risk of ulceration.
Foot health questionnaires suggested that orthoses improved
subjects’ perception of foot health. Compliance appeared to be
good. Gait speed increased significantly in both sub-groups.
5. Lavery (1997) investigated the effect of footwear with and
without an unmodified 4 mm plastazote/urethane insole on
mean peak pressure in a sample of 32 subjects with existing or
recently healed diabetic, neuropathic plantar ulcers. The
insoles reduced mean peak pressures at ulcer sites by an
additional 5.4 – 20.1% from baseline and a similar trend was
observed at non-ulcerated areas of the foot. Study quality was
poor.
64
Included studies concluded that one or more insoles/orthoses were
effective at redistributing PPP, reducing PTI (where collected) and
increasing contact areas in a variety of populations. The case for custom-
moulding over “off-the-shelf” shoe inserts was very limited. Simple insoles
had significant impact on pressure variables. Moulded insoles were well-
received.
Visco-elastic heel orthoses appear to distribute pressure away from the
heel to the 1st MTPJ and hallux in a small group of subjects with treated
heel pain.
External shoe adaptations
1. Postema et al (1998) tested rocker soles with 42 patients with
primary metatarsalgia. Force impulse was reduced over the lateral
and central metatarsal heads by 10.5% and 15.1%. PPP was
reduced by 7.6% and 15.7% over the same areas. The addition of
insoles produced further off-loading which was independent of the
rocker sole. The sample composed of 41 women out of 42
subjects. The authors do not describe metatarsalgia as confined
exclusively to women. This sample is, therefore, biased.
There is limited evidence from a moderate quality multi-centre RCT that
rocker soles reduce forefoot pressure in a sample of women with primary
metarsalgia.
65
Discussion
Heterogeneity of studies made pooling results impossible. Methodological
quality was generally poor. Qualitative synthesis provides reasonable
evidence from one RCT that insoles/orthoses are effective in redistributing
plantar pressure. Evidence for TTCs, RCW and footwear is very limited
because of small sample sizes, unique studies and poor quality. There is
limited evidence that a version of the rocker sole reduces loading over the
metatarsals. Visco-elastic heel pads redistribute pressure away from the
heel in one small study.
Comparing the results for the diabetic studies with those of Spencer
(2000) on preventing and healing diabetic ulcers, some similarities
emerge. In preventative studies, orthotic devices appeared effective in
preventing ulcers and treating callus. There was limited evidence that
TCC’s are effective in treating ulcers. No trials of RCWs were identified.
Preventative studies were underpowered.
Crawford and Thomson’s (2003) review of interventions for treating plantar
heel pain found little evidence for treatment (including heel pads and
orthoses) over no treatment.
Both reviews mention small sample sizes and the need for multi-centred
RCT’s to reduce the risk of Type I errors. Similarly, in this review, study
groups were generally small and only one (Postema 1998) was multi-
centred. Poor methodological quality was typical of included studies.
66
The objective of the review was to consider whether footwear, orthoses
and casts redistributed plantar pressure. Reviewed literature generally
supports this. This suggests either an overwhelming case has been
made, many Type I errors or a publication bias in English language
literature towards releasing only positive results. Better quality research is
required to clarify this.
Work started by the Foot Pressure Interest Group in providing protocol
guidelines based on research and best practice goes some way towards
providing consistency between studies and should be more widely
adopted. Three trials (Armstrong 1997; Fleischli 1999 and Lavery 1997)
were by the same team of researchers and showed many similarities.
Fleischli (1999), in particular, cites heavily from the team’s output (14 from
28 cited papers). There are potential benefits in developing consistent,
good quality protocols but there are dangers if the template devised is
poor (all three studies scored low) and if poor research is then repeatedly
repackaged.
Most studies did not evaluate the long term effects on subjects and
interventions. Barnett (2002) noted quite rapid degradation of
interventions over 6 months. A synergy was noted between insole and
shoe as the insert moulded to the individual foot and shoe shape and
walking speed increased in subjects with moulded orthoses. These
67
outcomes are worth investigating further. A general weakness of ethical
considerations in some studies was a concern.
A mixed methods approach demonstrated benefits in the two studies
using it, suggesting the weakness of the link between pressure and pain
(Postema 1998) and to identify factors affecting patient compliance.
(Barnett 2002) Qualitative research can be a valuable adjunct to
quantitative studies.
Shear stress may be important in understanding the limited correlations
found between pressure and pain or pressure and ulceration. It is a
weakness of current in-shoe technology that shear stress cannot be
measured.
The evidence suggests that footwear and orthoses redistribute plantar
pressure but the value of this to clinical practice is unclear as there is no
conclusive evidence that the pressure variables measured are the most
significant in treating the insensate or painful foot.
Weaknesses in the study
The review is weakened by being single-authored. This may have
introduced bias into the search, selection and review of the literature. A
lack of specificity during searching may have resulted in relevant studies
being missed. Limiting the review to research in English may have
68
introduced a publications bias. The use of unpublished literature is also
weak.
Reviewer’s conclusions
Implications for practice
There is evidence from a single centre RCT that simple cleron insoles are
an effective intervention for pressure reduction in low risk diabetic patients
and moulded inserts are appropriate for higher risk patients without foot
deformity. The insoles deteriorated significantly over 6 months and
should be replaced regularly. Research is required to assess the most
effective and efficient time scale.
Visco-elastic heel orthoses appear to distribute pressure away from the
heel to the 1st MTPJ and hallux in a small group of subjects with treated
heel pain
There is limited evidence from a small unique trial that rocker soles reduce
plantar pressure over the central metatarsals in women with primary
metatarsalgia.
Implications for research
.
• Multi-centre large scale RCTs are required to evaluate the
effectiveness of footwear, orthoses and casted devices for the
treatment of the insensate and painful foot.
69
• development of standard measures and research protocols is
urgently required to improve comparison of outcomes.
• Further research is needed to identify significant pressure
variables.
70
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Appendix 1:Draft protocol guidelines: in-shoe measurement
(Barnett 1998)
Standardisation of Report
• system specifications (thresholds) should be standardised
• floor surface
• data collection run
• socks
• velocity
Manufacturers’ protocols
• should be acknowledged and understood
• usually require acclimatization, bedding in and in-shoe calibration
• should be stated in reporting
Floor and walkway
• should be non-slip, flat, level and stable
• a figure of eight if possible
• protocols should excluded acceleration and deceleration data
• data should be recorded mid-cycle
• PC and wires should not distract
Footwear
• For longitudinal studies, standardised, manufacturer supplied
footwear should be used, depending on research question
92
• For intervention studies, patient’s own comfortable shoes should be
used. Should be classified and the degree of wear noted.
• Should reflect real-life footwear
Socks
• Pop socks (thin nylons)
• Dressings removed and film dressings used to cover wounds
Callus
• State whether callus has been removed and why. Should apply to
all subjects
Walking speed
• Self-selected at comfortable pace decided by subject
• Velocity noted and reported
Inserting and removing insoles
• Controlled by researcher
• Allow for bedding in
Calibration
• Reflect real-life, not rely on bench testing
• Follow manufacturers’ guidelines and publish these.
93
Appendix 2: Indexed terms from papers checked against inclusion
and exclusion criteria
Participants: adults; human; military personnel; diabetic foot [prevention
and control]; diabetic foot[therapy]; foot[physiology]; gait[physiology],
aged; metatarsalgia; cumulative trauma disorders[prevention]; foot
disease[complications]; obesity[complications]; pain[physiopathology];
pain[therapy]; diabetes mellitus; foot deformities [acquired]]; foot disease
[complications]; plantar fasciitis
Interventions: Orthoses; foot: sport shoes; casts: casting: device; shoe;
foot orthoses; orthotic devices; shoes; shoes [adverse effects]; cast,
surgical; metatarsophalangeal joint; foot sole; forefoot [human]; metatarsal
bone; polyurethanes; silicones; metatarsus; heel
Outcomes: Pressure measurement; pressure; transducers; pressure
sense; weight-bearing; piezoelectricity; sensor; force; stress, mechanical;
running; risk factors; patient satisfaction; risk assessment; walking; body
weight; gait; activities of daily living; ankle pressure; physical stress.
Study Design: controlled study; quantitative diagram; analysis of
variance; crossover studies; double-blind method; multivariate analysis;
clinical trials; conference paper; major clinical study; cohort studies
94
Appendix 3: Crossover trials assessed against quality criteria
(Griffiths 2004)
Armstrong Fleischli Hsi Lavery Postema Redmond
Is the research question
clearly focussed?
0 2 2 2 2 0
Is the study grounded on an
adequate knowledge base?
1 0 2 2 2 2
Was the research
methodology appropriate
for the research issue?
1 2 1 2 2 2
Was the study design
appropriate to the issue?
1 2 2 0 2 0
Were ethical issues
recognised and addressed?
0 0 2 0 0 0
Was the sampling strategy
appropriate and clearly
explained?
1 0 2 2 1 0
Were all of the participants
accounted for at its
conclusion?
2 2 2 0 2 2
Were there clear inclusion/
exclusion criteria?
1 0 2 0 1 0
Were measures taken to
reduce bias?
0
Sampling procedures 0 0 2 0 1 1
Intervention Protocol 1 1 1 0 2 2
Was the data collection
method sound?
1 0 1 0 1 0
95
Was the data analysis:
Appropriate 0 0 1 0 1 0
Clearly described 0 0 1 0 1 2
Justified 0 0 1 0 1 2
Is there sufficient detail to
assess the credibility of the
findings?
0 0 1 0 1 0
Can the findings be applied
to your situation?
0 0 1 0 2 0
Were all clinically important
outcomes considered?
0 0 1 2 1 1
Are the benefits worth the
harms and costs?
0 0 1 0 2 0
9 9 26 10 22 14
Coding: 0= not met Quality < 20 = poor
1= partly met 20-30= moderate
2= well met > 30= good
Possible total =36
96
Appendix 4 Parallel trial (Barnett 2002) assessed against Consort
Statement (Moher, Schulz, and Altman (2001)
1. title and abstract: prospective randomised clinical control trial.
Participants randomly assigned to EVA orthoses or 3 mm Cleron
insoles. Qualitative research on patient perception of foot health
and diary of wear. Longitudinal study (6 months)
2. Introduction/background: thorough
3. Participants: clear inclusion and exclusion criteria. Location of data
collection unclear
4. Interventions: control: 3mm cleron insole, intervention: non-
customized, pre-formed, TEC urethane orthoses with EVA cover.
Used in patients’ own shoes between readings. Measures taken at
baseline, 3 months and 6 months in standardized shoes
5. Objectives: specific hypothesis, clear objectives
6. Outcomes: peak plantar pressure and pressure time integral (whole
foot and 9 masks). Foot contact area, walking speed. Bristol Foot
health questionnaire, diary of use. Measures taken from 10 right
steps and 10 left steps. Calibration and acclimatization reported.
Callus debrided, standard nylon socks, lesions covered with Opsite.
Thickness of insoles/orthoses recorded at baseline and follow-ups
to assess degradation. All assessments by lead researcher.
7. Sample size: a priori power calculation of 47 subjects per group.
103 participants recruited.
97
8. Randomization: letters in envelope in box. Subjects assigned as
recruited.
9. Allocation concealment
10. Implementation: see 8.
11. Blinding: control group also an intervention. Both groups told
contributing to research. Not double-blinded
12. Statistical methods: normal distribution assessed, used ANOVA for
multivariate analysis
13. Participant flow: described, including drop-out from each group with
reasons. No diagrammatic representation of flow
14. Recruitment: dates not given. Intervals of follow-up given
15. Baseline data: provided in detail for both groups. Cleron group
significantly older than intervention group.
16. Numbers analysed: 117 recruited, 14 left study before completion –
reasons explored. Data analysed on “intention to treat” basis
17. Outcomes and estimation: results summary provided for each
group, by mask areas and whole, by foot type, for participants with
above average pressures for group. P= 0.01
18. ancillary analyses: developed, trialled and used Bristol Foot Health
Quesionnaire. Results reported. Diary of use information
assessed for patient compliance and patient comments on ease of
use, comfort, etc.
19. Adverse events: causes of drop-out. Discomfort with Cleron
explored. Increased walking speeds in both groups, particularly
98
with orthoses. Possible causes discussed: confidence with testing,
improved foot functionality
20. Interpretation: would like more time to consider increased walking
speeds. Changes to interventions over time not adequately
predicted by thickness. Problems with sensor resolution over digits
with Emed Pedar. Differences between actual and expected
outcomes discussed. Similarities/difference with earlier literature
explored. Statistics used appropriately.
21. generalizability: good. Inclusion criteria sufficiently broad to allow
clinical application to the majority of DM patients without major
complications or deformity
22. overall evidence. Good. Only longitudinal study.
Appendix 5:Trials assessed against Protocol for foot pressure
measurement
Armstrong Barnett Fleischli Hsi Lavery Postema Redmond
Manufacturer'sProtocols no yes no yes no no no
Floor/walkway no yes no no no yes yes
Footwear no yes no yes no yes no
Socks no yes no no no no no
Dressings no yes no n/a no n/a n/a
Callus no yes no no no no no
Mid-gait steps yes yes yes yes yes no yes
self-set speed yes yes yes yes yes yes yes
Walking speed no yes no yes no no no
insert/remove insoles no yes no yes no no no
Calibration no yes no yes no no no
99
Appendix 6: Statistics
sample size calc Power calc Stats test
Armstrong No Yes
ANOVA and tukey’s post hoc
studentized range test
Barnett Yes Yes
t-tests for matched pairs,regression
analysis
Fleischli No No
Univariate and multivariate ANOVA and
tukey’s
Hsi Yes Yes
two-factor ANOVA, F-test for
significance, coeffs of reliability and
variability
Lavery No No
Univariate and multivariate ANOVA.
Tukey and Paired T-Tests
Postema No No
Paired T-Test for repeated measures.
Multivariate ANOVA. One –sided
Fisher exact tes
Redmond No Yes
Checied distribution for normalality.
ANOVA Friedman and Wilcoxon for
non-ratio data
100
Appendix 7: Interventions studied in included trials
Armstrong Barnett Fleischli Hsi Lavery Postema RedmondViscoelastic Heel orthoses
X
Standard insoles (6.5 mm polymeric foam flat inserts
X
Custom-made Insoles (6.5 polymeric foam)
X
Rocker Bar X TCC X X Darco orthowedge/half shoe
X
Darco rigid post-op. shoe
X
DH pressure relief walker
X X
Accomodative foam and felt dressing
X
Card insole with 60 EVA varus rearfoot post
X
Modi Root orthosis polypropylene shell with PVC cover and 60 EVA varus rearfoot post
X
Cleron insole: 3mm flat insert
X
EVA (off the shelf” moulded orthoses
X
Aircast pneumatic walker
X
Extra depth shoes with PW Minor inlays men/ women
X
SAS comfort shoes for men and women
X
New Balance cross-trainers for men and women
X
Plastazote/urethane insole, preformed
X
Baseline Footwear Reebok sneaker X Standard orthopaedic shoe
X
Rubber soled canvas oxford
X X
Own shoesx X Dunlop athletic shoes
X
Socks unknown Thin nylons
No socks
Own socks
Unknown unknown unknown
101
Appendix 8: Variables collected in included studies
Armstrong Barnett Fleischli Hsi Lavery Postema RedmondPeak Pressure N cm2 kPa cm2 N cm2 kPa cm2 Ncm2 Ncm2 kPa cm2
Pressure time integral N.s/cm2 Kpa.s/cm kPa.s/cm2 kPa.s/cm2
Mean contact area Cm2 Cm2
Average step length x Average step time x Walking speed x x Foot to sensor contact time x Force impulse x Force time integral x Maximum force x Bristol foot health questionnaire x Diary of wear x Pain questionnaire x Patient preference x
102
Appendix 9: Masking and sampling speed data
Armstrong
Heel pressures collected. Masking not specified. Sampling
speed not specified
Barnett 9 regions of foot masked and whole foot. Sampling speed 99 Hz
Fleischli
Pressure over existing or former ulcers: masking not described.
Sampling speed 50 Hz
Hsi Parotec. Over whole foot. Sampling speed 100 Hz
Lavery
Pressure at ulcer sites and hallux, 1st met and 2nd-5th met
Masking not described
Sampling speed 50 Hz
Postema
Pressure over four regions of forefoot, established using Emed
platform. Sampling speed 70 Hz with Emed Mikro
Redmond
Six masks over whole foot – lateral digits discarded. Sampling
speed 50 Hz
Appendix 10: Use of data from Right/Left feet (Menz 2003)
Armstrong (1999)
Does not specify if pressures are taken for both feet and pooled or
only the ulcerated foot.
Barnett (2002)
Tests 10 right steps and 10 left steps for each participant at
baseline and each follow-up but appear to pool data.
Fleischli (1997)
103
104
Mean peak pressures over the site of ulceration. Sample size
implies one ulcer per subject and therefore assume only ulcerated
foot is included in study but not specified.
Hsi(1999)
Studies 22 consecutive patients with unilateral heel pain. Assume
that only data from painful heel is used but not specified.
Lavery(1997)
32 consecutive patients with diabetes and recent or existing
neuropathic ulcer. Pressure measured over ulcer. Presume one
ulcer per patient but not specified.
Postema (1998)
42 primary metatarsalgia patients. Specified use of the most
painful foot or – if no pain – a random choice is made (method not
specified). Explicit states that this is to avoid dependency of
measurement.
Redmond(2000)
Tested 22 patients with abnormal pronation. Tested results from
right and left, found no statistical difference and therefore pooled.