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Bioelectricity and microcurrent therapy for tissue healing-a narrative review

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Abstract

Background: Microcurrent therapy (MCT) uses electric currents similar to those produced by the body during tissue healing. It may be a particularly beneficial where endogenous healing has failed. Aim: To review evidence regarding microcurrent in tissue healing and the application of MCT. Methods: All peer-reviewed studies concerning microcurrent and MCT were sought, and representative literature was synthesised to indicate the scope and weight of current evidence. Results: Microcurrent appears to play a significant role in the healing process, and MCT can promote healing in a variety of bone and skin lesions. The evidence for other tissues is encouraging but presently scant. Conclusion: MCT may have unrealised potential in the treatment of dysfunctional tissue healing and deserves greater attention by researchers and clinicians.
Bioelectricity and microcurrent therapy for
tissue healing – a narrative review
Leon Poltawski and Tim Watson
School of Health and Emergency Professions, University of Hertfordshire, Hatfield, AL10 9AB, UK
Background: Microcurrent therapy (MCT) uses electric currents similar to those produced by the
body during tissue healing. It may be a particularly beneficial where endogenous healing has failed.
Aim: To review evidence regarding microcurrent in tissue healing and the application of MCT.
Methods: All peer-reviewed studies concerning microcurrent and MCT were sought, and
representative literature was synthesised to indicate the scope and weight of current evidence.
Results: Microcurrent appears to play a significant role in the healing process, and MCT can
promote healing in a variety of bone and skin lesions. The evidence for other tissues is
encouraging but presently scant.
Conclusion: MCT may have unrealised potential in the treatment of dysfunctional tissue healing
and deserves greater attention by researchers and clinicians.
Keywords: bioelectricity, electrotherapy, microcurrent, tissue healing
Introduction
Contemporary accounts of tissue healing are typically
expressed entirely in terms of biochemistry.
1–4
The
actions of substances such as cytokines and growth
factors are said to initiate and mediate the various
stages of inflammation and repair that normally follow
tissue damage.
5
Yet evidence which has accumulated
over many decades suggests that a full description of
the physiology of healing must also include the role of
bioelectricity – accumulations and flows of charge that
are generated endogenously, within the body. The
importance of bioelectricity in functions such as
nervous system signalling and muscle contraction has
been long appreciated, but it is also involved in many
other physiological processes. These include the
development, adaptation, repair and regeneration of
tissues throughout the body.
6–9
Recognition of bioelectricity’s role in tissue healing
provides a rationale for the therapeutic application of
electrical stimulation, particularly in cases where natural
repair processes have broken down. Microcurrent
therapy (MCT) is an example of this. Uniquely amongst
the various electrotherapeutic modalities, MCT involves
application of voltages and currents of similar magni-
tude to those generated endogenously during normal
tissue healing. Althoughrelativelyunknownand
currently little used by physiotherapists outside North
America, MCT has been shown to be of benefit in
several types of tissue healing and it may be effective in
others. It appears to stimulate healing generally, and not
just one element of the process; it has very few side
effects; and it may offer an effective treatment for
musculoskeletal disorders such as chronic tendinopa-
thies where normal healing has become dysfunctional.
This paper outlines current thinking on the role of
bioelectricity in healing, presents empirical evidence
regarding MCT for the promotion of tissue healing,
and suggests implications for both clinical and
research communities. The majority of published
research in this area is concerned with bone and skin
lesions, but patterns and mechanisms of healing in
these tissues share features with those seen in damaged
tendons, ligaments and other musculoskeletal struc-
tures.
10–12
Therefore the evidence presented here is of
relevance to researchers and clinicians concerned with
a variety of musculoskeletal disorders.
Bioelectricity and healing
The human body, in common with other living
organisms, expends a significant proportion of its
104
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DOI 10.1179/174328809X405973 Physical Therapy Reviews 2009 VOL 14 NO 2
energy generating electricity.
13
In fact the body is a
conglomeration of electric batteries. Every cell main-
tains a voltage across its external membrane, and
across the membranes of its organelles.
14,15
This is
achieved by the active transport of ions, particularly
sodium and potassium, against their concentration
gradients, establishing charge separations that con-
stitute a potential difference or voltage across the
membrane.
16
Aggregates of cells also set up voltages
across various tissue layers, including cutaneous and
corneal epithelium, vascular and intestinal walls, and
the cortex and periosteum of long bones.
14,15,17–21
These voltages are of the order of millivolts (mV) in
magnitude, and where there is a conducting pathway
they cause the movement of ions within tissue,
constituting a bioelectric current, typically in the
microamp (mA) range.
14
At the cellular level, bioelectricity is involved in the
transport through the membrane of ions that can
influence cell behaviour. Even in non-excitable cells
there are voltage-gated channels controlling the
passage of such ions.
22
At the tissue level, endogen-
ous fields are intrinsic to a number of metabolic
processes, including development, adaptation and
repair. They can influence cell morphology and the
growth of body parts during foetal develop-
ment;
13,23,24
they are generated when connective
tissues such as bone and tendon are stressed, and
can influence adaptive modifications in the extra-
cellular matrix;
25–28
and when tissue is damaged they
set up currents that appear to drive elements of the
healing response.
17,29–32
The currents diminish as
healing progresses, with normal values being re-
established once healing is complete.
17,23,32,33
That bioelectricity is intrinsic to such processes –
rather than a mere by-product – has been established
by a wealth of experimental evidence. Perhaps the
most convincing is that setting up a voltage in
opposition to the endogenous one, or blocking the
passage of biocurrents, can slow or abolish the
healing response in a variety of tissue types.
15,33–35
In vitro studies have also demonstrated that applica-
tion of electric fields and currents similar to those
generated within the body can cause significant
changes in the structure and behaviour of cells.
Application of microcurrent to tissue has been found
to boost the number of organelles responsible for
cellular activities, and to increase concentrations of
ATP, the cellular currency of energy.
36,37
These
changes can facilitate cell proliferation and protein
synthesis, which have been found to increase when
microcurrents are applied to the constituent cells of
skin,
38,39
tendons,
40,41
cartilage
42
and bone.
43
Such
effects are highly parameter-dependent, however.
Larger currents or alternating microcurrents at
certain frequencies have been found to reduce cell
proliferation or induce cell death in some cases.
44,45
Ion channels in cell membranes may migrate under
the influence of an applied field, resulting in
cytoskeletal modifications, including creation of
membrane projections that enable cell movement.
24,37
Directed movement of cells within an electric field –
known as galvanotaxis – has been observed with
many cell types. These include leukocytes and
macrophages, which are key mediators in different
stages of healing,
46
as well as a variety of cells
responsible for tissue formation, such as keratino-
cytes, vascular endothelial cells, osteoblasts, osteo-
clasts, chondrocytes and fibroblasts.
24,37,47,48
Different cell types have been found to move in
opposite directions, and reversing the field reverses
the direction of migration.
37,49
At the tissue level, unidirectional fields and direct
currents (DC) can promote vascular permeability
50
angiogenesis
51
and neural sprouting
31,52
as well as
formation of new skin, bone, cartilage and soft
tissue.
39,53–57
Such findings are significant because
they suggest that applying fields and currents with
similar parameters to bioelectricity may be used to
stimulate tissue healing. Cell migration, proliferation
and synthesis of new tissue are all essential compo-
nents of the healing process.
1,46
If applied electricity
can mimic endogenous electrical signals that guide
cellular behaviour, then a therapeutic option may be
available where natural healing has failed.
Therapeutic microcurrent
There are various forms of electrotherapy that may
deliver average currents in the microamp range, such
as high voltage pulsed current, and high frequency
alternating currents induced by electric or electro-
magnetic fields, e.g. pulsed short-wave or non-
thermal pulsed radio frequency. However, the wave-
forms produced by these modalities are quite unlike
those of any observed endogenous currents and
voltages, which tend to be unidirectional, and of
constant or slowly varying amplitude.
14
Since MCT is
predicated on the basis that it mimics endogenous
bioelectric signals, the main focus here is on those
studies that use electrical stimulation with similar
parameters. A good deal of evidence regarding the
effects of microcurrent on tissue healing has accu-
mulated over recent decades. Where clinical trials
have been reported, they are presented, though
Poltawski and Watson Bioelectricity and microcurrent therapy for tissue healing
Physical Therapy Reviews 2009 VOL 14 NO 2105
reference to in vitro and animal studies is also made
where clinical trial data is scarce.
Bone
Electrical stimulation was used for promotion of
bone healing in the early nineteenth century. English
physician John Birch applied DC to the ends of a 13
month-old non-uniting tibial fracture via percuta-
neous electrodes.
58
After 6 weeks of treatment the
fracture had consolidated. Other historical examples
of electricity being used in this way are recorded, but
the therapy later fell into disuse. It was revived in the
mid-twentieth century, when a scientific rationale for
its application was developed on the basis of in vitro
and animal experiments. In the 1950s several workers
found that application of microcurrent to bone could
initiate osteogenesis in both normal and damaged
bone.
59,60
Later studies investigated the effects of
parameters such as current size, polarity and elec-
trode material and configuration on the process.
61–63
New bone could be laid down by DCs of about
20 mA, with maximal formation occurring at the
cathode (the negative electrode). Currents above
30 mA could cause bone resorption or osteonecro-
sis.
55,62,64
Such data provide a persuasive rationale
for the use of microcurrent to stimulate bone healing,
and subsequent in vivo animal studies suggested that
it might be beneficial for several clinical applications,
including fresh fractures, delayed and non-uniting
fractures, osteotomies and spinal fusions, although
parameter choices varied considerably and not all
applications were successful.
65–70
Reviews of such
studies are available.
71,72
Clinical studies
The earliest modern application of MCT for human
bone healing was to non-uniting fractures. In 1971,
Friedenberg and colleagues published a case study in
which a malleolar fracture, which had failed to unite
after more than a year, was healed within 9 weeks by
treatment with DC of 10 mA via a cathode inserted
into the fracture site.
73
Several larger studies fol-
lowed, in which MCT was applied to delayed or non-
uniting fractures. Delayed unions are those that take
longer than would be expected for the particular
fracture site and patient characteristics; non-union is
said to occur when healing stops and union is not
achieved after 6–8 months.
74
In 1977 Brighton and
colleagues reported a study involving treatment of 57
lower and upper limb non-unions with 10–20 mA,
delivered to the site by 2–4 cathodes for 12 weeks,
followed by 12 weeks of continued immobilisation.
75
Of those treated, 76% went on to develop full union,
with most failures accounted for by insufficient
current delivery or breakage of electrodes. In a
follow-up multi-centre study 84% of 178 non-unions
treated using a similar protocol achieved union.
Complications were reported as minor.
76
Another
multicentre trial in a different country used the same
current but delivered through a single cathode to 84
patients with either delayed or non-union,
77
mostly of
the tibia or femur. Time to achieve union varied
between 12 and 36 weeks. A 10-year follow-up
assessment of 37 of the patients enrolled in this trial
found normal bone remodelling, continued union
and no side effects of the electrodes that were left in
situ (the remaining participants were unavailable for
review).
78
Microcurrent pulsed at 20 Hz has also been
evaluated and found beneficial with a mixed caseload
of non-uniting fractures, congenital pseudarthroses,
osteotomies and leg-lengthening procedures.
79
DC of
pulse amplitude 20–25 mA and duration 30 ms was
applied via a cathode wrapped around or threaded
through the fracture site and with the anode
implanted in the medulla (as opposed to the
subcutaneous positioning used in other trials).
Treatment times varied according to case until union
was observed radiographically, and varied between 2
and 12 months. The overall success rate was 87%
although adjunctive treatments and individual char-
acteristics varied considerably. Authors of one of the
earlier studies
75
reported that they found that
constant DC always produced superior outcomes to
pulsed current, although they presented no relevant
parameter or outcome data.
Some of these studies are rather dated and do not
meet contemporary reporting standards for clinical
trials. The absence of a formal control group is
justified by the fact that usually no bone healing had
been observed for months, and spontaneous recovery
in such cases is rare, so participants were considered
to be acting as their own controls.
76
However placebo
and time effects cannot be ruled out when evaluating
their evidence. The lack of more recent studies may
reflect the greater popularity of less invasive electro-
therapies, although MCT appears superior in selected
cases. A comparison with capacitative and inductive
coupling as adjuncts for bone graft treatment of tibial
non-unions reported in 1995 found that microcurrent
was more effective with high risk cases such as those
with atrophic non-unions or previous graft failure.
80
Where there were no identified risk factors, none of
the electrotherapies was superior to graft alone.
Poltawski and Watson Bioelectricity and microcurrent therapy for tissue healing
106 Physical Therapy Reviews 2009 VOL 14 NO 2
Although non-invasive forms of electrotherapy
have superseded MCT for some applications, it has
continued to be employed with lumbar spinal fusions,
where there is evidence of its superiority over other
types of electrical stimulation. Such fusions are used
in cases of disabling joint instability or disc degen-
eration, and normally involve a bone graft and
instrumentation. Failure rates can be as high as
40%,
81
but may be reduced substantially by the
application of MCT. After its first clinical use was
reported in 1974,
82
DC application, typically of
20 mA applied by a single or multiple cathodes to
the fusion site for 5–6 months, was subject to
evaluation in several trials.
83–85
In these studies
patients receiving MCT in addition to standard
treatment had successful fusion rates of 81–96%,
compared to 54–81% for those on standard treatment
alone, as assessed by radiographic and clinical
criteria. Results for methodologically sound con-
trolled trials consistently indicate statistically signifi-
cant outcomes in favour of DC MCT compared
with control groups.
86
It is particularly effective
when used in high risk cases such as those with
previous failed fusions, multiple level surgery,
smokers and those with co-morbidities such as
diabetes and obesity,
87–89
and has a stronger favour-
able evidence base than either capacitative or
inductive coupling, particularly for posterior
fusions.
90
An economic evaluation of the therapy as
an adjunct in spinal fusion surgery
91
also found that
it provided significant cost savings and shorter in-
patient stays.
Smaller studies have suggested that DC MCT may
be useful in other bone lesions, including high risk
ankle and hind-foot fusions
92,93
and selected con-
genital pseudarthoses.
94–97
Their findings have yet to
be confirmed by larger trials. Two controlled trials
have suggested that MCT may also accelerate healing
in fresh fractures,
98,99
though this application is still
largely unexplored.
Systematic reviews of trials have concluded that the
best evidence for promotion of bone healing by
application of small electric currents is in cases of
non-uniting lower limb fractures and spinal
fusions.
71,86,88,90,100–105
Meta-analyses have been wea-
kened by pooling data from trials using heteroge-
neous groups and treatment parameters, and even
different forms of electrotherapy.
86,101
Nevertheless,
consideration of the evidence regarding MCT in
particular suggests that its application, usually for
several months, may enhance tissue healing in a
variety of bone lesions.
Skin
Since it is easily accessible for study, skin is the tissue
in which the bioelectrics of healing have perhaps been
subject to the greatest scrutiny. Reviews providing
accounts of in vitro and animal studies are avail-
able,
53,72,106
and only the human and clinical studies
are dealt with here. Several authors have identified
the seventeenth-century use of charged gold leaf for
resolution of smallpox lesions as the first example of
electrotherapy for human skin healing.
53,107,108
In
fact there is no mention of electric charge in the cited
source.
109
Charged gold leaf, which would deliver a
small and diminishing current to adjacent tissue, was
used successfully in the 1960s to assist healing in
surgical vascular wounds and cutaneous ulcers.
110,111
However, charging appears to have been considered
an aid to adherence of the leaf rather than an agent of
healing in itself. Nevertheless, more recent studies
have consistently concluded that electrical stimula-
tion, including MCT, can indeed promote healing in
various types of human skin wounds, particularly
ulcers. The first of these was reported in 1968 by
Assimacopoulos who, following successful use of
microcurrent to accelerate healing of surgical scars on
rabbit ears,
112
tried the treatment with recalcitrant leg
ulcers in three patients.
113
DC between 50 and
100 mA was delivered continuously for several weeks
via a stainless steel mesh cathode soaked in saline and
placed on a moist dressing on the wound, and an
anode affixed to the thigh or abdominal wall. All the
wounds healed within six weeks and no side effects of
treatment were reported.
In a larger study, Wolcott and colleagues used
MCT with 83 ulcers of varying aetiology in 67
patients.
114
A measure of control was introduced by
assessing but not treating additional ulcers in eight of
the sample patients. ‘About three quarters’ of the
patients had failed to respond to other conservative
treatment. DC between 400 and 800 mA was applied
via a copper mesh cathode over the wound and anode
on skin 15 cm proximal. The current level was
determined individually, adjusted so as to avoid
bleeding or excess exudate production, and was
delivered for 2 hours, thrice daily for several weeks,
in some cases months, until healing occurred (a full
breakdown of durations was not given). The protocol
involved a polarity-swapping element, based on early
experience that healing would often plateau after a
few days and could be restarted by reversing the
polarity of the electrodes. Over a mean treatment
time of 7.7 weeks, there was a mean volume
reduction in treated wounds of 82%, with a mean
Poltawski and Watson Bioelectricity and microcurrent therapy for tissue healing
Physical Therapy Reviews 2009 VOL 14 NO 2107
healing rate of 13.4% per week. Thirty-four lesions
(40%) healed completely. These figures mask a wide
range of individual and group responses, with para-
plegic patients (presumably mostly spinal cord
injured) consistently responding less well to treat-
ment. Of the eight patients (mostly paraplegic) with
microcurrent-treated and control ulcers, mean
volume reductions were 93% (range 75–100%) in the
MCT ulcers and 33% (range 0–75%) in the control
ulcers. The study evidence is weakened by the lack of
information on duration of ulcers, the inclusion of
patients for whom standard treatments had not been
tried, early termination of electrotherapy protocol in
more than half of the sample, and the small size of the
control group. Even so, it began to build the case that
MCT could assist healing in a variety of skin ulcer
types.
MCT using similar protocols – and various
alternatives – were later used in several larger
controlled trials by other groups.
115–121
These
involved several skin ulcer types including those due
to venous and arterial insufficiency, secondary to
diabetes, and pressure ulcers following spinal cord
injury. MCT typically involved currents of several
hundred microamps, often continuous DC but some-
times pulsed or low frequency biphasic. Where
currents were unidirectional, the anode was normally
placed on the wound, within a moist dressing.
Treatment times were usually 1 hour or more each
day for several weeks or even months. Healing was
measured in terms of percentage reductions in wound
surface area or volume over a defined time, and in the
majority of cases ulcers receiving MCT as an adjunct
to conventional treatment healed more quickly and
completely than those receiving conventional treat-
ment alone.
More recent studies have suggested that MCT may
also be effective with other types of skin wounds. In a
trial involving 30 patients, microcurrent was found
more effective than conventional treatment in pro-
moting skin graft healing following thermal injury.
122
A DC current between 50 and 100 mA was applied
continuously for several days via an anodal dressing
on the wound. Stimulated wounds closed in an
average 4.6 days compared to 7.2 days for controls.
A series of case studies involving application of
monophasic microcurrent to pressure sores, an
infected venous ulcer and a recalcitrant pilonidal
sinus also found evidence of benefit in terms of
accelerated healing and reduction of bacterial
load.
123
The novelty of these cases was that the
current (of unspecified magnitude) was provided by a
proprietary dressing with an integrated circuit,
battery and electrodes.
Reviews of electrical stimulation for skin wound
healing have consistently concluded that the weight
of evidence is in its favour when it is used as an
adjunctive treatment with other conservative man-
agement strategies.
53,86,108,124–128
In the USA, gov-
ernment and private medical insurers pay for its use
with recalcitrant ulcers due to pressure, arterial or
venous insufficiency and diabetes.
127
However, most
reviews have not considered the different modalities
separately, because the numbers do not justify
subgroup analysis. Where MCT studies are consid-
ered alone, the range of protocols employed means
that optimum parameters cannot yet be identified.
Both continuous and pulsed, monophasic and bipha-
sic, anodal and cathodal stimulation seem capable of
promoting healing. The parameters that are sup-
ported by a majority of studies are current size (in the
hundreds of microamps), treatment time (typically
several weeks, for hours rather than minutes each
day) and application directly to the wound bed.
Monophasic or ‘unbalanced’ currents (those with a
net delivery of charge) are more common in the
studies indicating MCT effectiveness.
Tendons and other tissues
Data from in vitro and animal studies, and a small
number of human trials, suggest that there may be
unexplored potential for microcurrent treatment of
lesions in soft connective tissue, particularly tendons
and ligaments. In these structures, the extracellular
matrix (ECM) is laid down by phenotypes of the
fibroblast, a cell that has been shown to migrate,
proliferate and increase synthesis of ECM proteins
under the influence of applied electric fields and
currents.
40,41,129–132
Tissue and animal studies
By using explants, whole tissue samples taken from
animals and maintained in laboratory cultures,
investigators have been able to conduct well-
controlled studies of the effects of applied current
on tendons and ligaments. Nessler and Mass reported
using these methods in 1987, when they applied
continuous 7 mA current for up to 6 weeks to
surgically transected and sutured rabbit flexor tendon
explants.
133
Bioassay and histological analysis
showed greater and more rapid fibroblast prolifera-
tion, protein synthesis and collagen deposition
consistent with normal tendon healing in stimulated
explants compared to their controls. These changes
Poltawski and Watson Bioelectricity and microcurrent therapy for tissue healing
108 Physical Therapy Reviews 2009 VOL 14 NO 2
were observed distant from the cathode, which had
been placed into the lesion, and the authors speculated
that the current density was too great close to the
cathode. Soon after, Cleary and colleagues investi-
gated the influence of various microcurrent parameters
by applying pulsed monophasic microcurrent to
chicken flexor tendon explants for 3 days, varying
current amplitude, direction and pulsing frequency.
130
They found that levels of fibroblast proliferation,
protein synthesis and collagen fibroplasia at the cut
surfaces of stimulated explants were significantly
greater than those of unstimulated controls. Effect
sizes were greatest at current densities of about 1 mA/
cm
2
, and at pulse frequency 1 Hz, and dropped off at
higher values. Applying the current longitudinally
maximised the effects, whilst no significant differences
between treated and control explants were found with
transverse application. This observation was explained
by other studies showing that fibroblasts lay down
collagen fibres parallel to the direction of the applied
field.
134,135
In a study using explants of rabbit flexor tendons
and their sheaths, longitudinal stimulation with
various DC microcurrent levels was applied for up
to 2 weeks.
41
Investigation of the cut surfaces
revealed evidence of cell proliferation and collagen
deposition in both treated and control samples, with
adhesions forming in the epitenon-sheath as a result.
Application of microcurrent caused different effects
according to current size. Above 1 mA there was
evidence of tissue degeneration and cell death, but at
0.5mA proliferation continued in the tendon sub-
stance but was significantly reduced in the sheath.
This observation rather astonishingly suggests that
microcurrent can selectively inhibit proliferation that
would lead to counterproductive adhesion formation
during sheathed-tendon healing.
In the first reported in vivo animal study, low level
current was applied to surgically wounded flexor tendons
of six ponies via a cathode implanted in the wound and
an anode 3 cm distal.
136
No gross or histological
differences were seen between treated and contralateral
control tendons at 4, 5 or 6 weeks post-injury. The
author speculated that the (unmonitored) current,
provided by a bimetallic strip, may have been too low
to affect healing. Later studies were more encouraging,
though a wide range of parameters was adopted, making
generalisation from their results problematic. Stanish
and colleagues transectedthemedialportionofthe
patellar tendons of nine dogs and divided them into three
groups, receiving plaster immobilisation, brief compres-
sion bandaging or constant 20 mAcurrentappliedviaa
cathode wrapped around the tendon.
137
After 6 weeks
the dogs were killed and the tendons removed with their
contralateral counterparts for comparison. Breaking
strengths as a percentage of the normal tendon values
were 47 and 50% for the first two groups, and 92% for
the MCT group. Though the sample sizes were small, the
difference is striking.
In a larger study,
138
the patellar tendons of 45
rabbits were transected bilaterally and cathodes
sutured into the lesions, anodes mounted on the
tissue surface. One limb was left untreated, the other
given 10 mA DC continuously, with tendons removed
at 3, 5 or 7 weeks for evaluation. Mechanical strength
was found to increase more rapidly in the early weeks
in stimulated tendons, whilst mature collagen forma-
tion was greater in the later weeks, compared to
controls. This suggested that MCT could accelerate
healing in both proliferative and remodelling phases
of healing.
Subsequent studies with rat Achilles tendons, knee
ligaments and joint capsules have consistently sug-
gested that MCT with a range of parameters can
accelerate repair and result in stronger tissue and
reduced contracture formation after injury, com-
pared to unstimulated controls.
56,139–143
Micro-
current has also been observed to promote rabbit
cartilage growth
57
and repair,
144
as well as rat
peripheral nerve regeneration.
52
DC or unbalanced
biphasic current was used in all the tendon studies,
but alternative current was also successfully
employed with other tissues. Treatment times varied
between 1 and 24 hours a day for between 1 and
4 weeks. Where currents were modulated, their
amplitudes were of the order of 100 mA (with
considerably lower average values), and electrodes
were implanted, usually delivering current parallel to
fibre orientation. The strength of the studies is in their
use of contralateral controls, allowing a cause–effect
relationship to be established. However their findings
cannot be aggregated because of heterogeneity in
their treatment parameters. They all used surgical
means to create lesions and animal models that are
imperfect analogues of human tissue disorders. The
lack of histological data also means that conclusions
cannot be drawn about repair processes. Despite
these limitations, they provide evidence that micro-
current can promote resolution of tissue damage, and
have justified progression to clinical trials of MCT.
Human studies
Following their work with surgically wounded canine
tendons, Stanish and colleagues reported on a series
Poltawski and Watson Bioelectricity and microcurrent therapy for tissue healing
Physical Therapy Reviews 2009 VOL 14 NO 2109
of more than 100 patients in which MCT was used
after surgical repair of torn Achilles and patellar
tendons and anterior cruciate ligaments.
137
A DC of
20 mA was applied (for an unreported time, pre-
sumably several weeks) via a cathode wrapped
around the lesion and a subcutaneous anode and
power-pack. The authors reported accelerated return
to full weight-bearing and function, and histological
analysis of 45 reconstructed ligaments 9 months after
surgery showed the tissue to be revascularised with
mature and well organised collagen. This was not a
formally controlled trial, however, and little numer-
ical data is provided for scrutiny.
MCT has been subject to trial with several
examples of chronic tendinopathy. One involved 48
people with Achilles tendinopathy of at least
3 months’ symptom duration, randomly assigned to
receive either microcurrent or conventional conser-
vative treatment.
145
A monophasic square wave of
amplitude 40 mA and frequency 10 Hz was applied
via surface electrodes placed transversely across the
lesion. Treatment was for 30 minutes daily over
14 days, followed by a regime of eccentric exercises.
Numerical measures of patient-rated pain and stiff-
ness and clinician-rated clinical status were recorded
at baseline and at 3, 6 and 12 months after treatment.
Statistically significant differences in favour of the
MCT group were found in these measures.
Sonography, which can be used to image changes
associated with tendinopathy,
146,147
was also
employed. The authors reported that sonographic
findings were ‘in agreement’ with these outcomes,
though specific data were not given. Improvements
were most marked in the first 3 months after
treatment. The study is weakened by non-standardi-
sation of the conventional treatment and a complex
and unvalidated scoring system used with the out-
come measures. However, the data are encouraging.
A more recent pilot controlled trial has used MCT
for chronic tennis elbow.
148
Sixteen people with
symptoms lasting at least 3 months were randomly
assigned to receive either a 6-week standardised
exercise programme or exercise plus MCT. Biphasic
square wave current, with a variety of parameters
including amplitudes 40 or 300 mA and frequencies of
0.3, 3 and 30 Hz, was used. Treatment was adminis-
tered via probes contacting the skin at various points
on the elbow and forearm for several minutes, 10
times over 3 weeks. Outcome measures were pressure
pain threshold at the tendon, grip strength and pain
on gripping, recorded at baseline and 1, 2, 3 and
6 weeks later. All participants improved but no
significant differences between groups were seen in
any of the outcome measures. The conclusions may
have been affected by the small sample size of the
study, but in any case it was hampered at the outset
by the use of MCT of very short duration and
methods of application that were given no scientific
justification by the authors.
Trials using microcurrent have been reported for
a range of other soft tissue lesions, including
plantar fasciitis,
149
delayed-onset muscle soreness
(DOMS),
150–152
radiation-induced fibrosis
153
and
osteoarthritis.
154
The outcomes of these trials suggest
– though not unequivocally – that MCT may have an
analgesic effect that is not due to sensory stimulation,
since the treatment is normally sub-sensory. Pain
relief may account for the improvement in other
outcome measures such as range of movement and
function. In one study there was also evidence of
mediation of the healing process. Serum creatine
kinase (CK) levels, which elevate following muscle
damage, were found to be lower in DOMS-induced
muscles after MCT than in an untreated control
group. The microcurrent was delivered by a skin-
mounted charged dielectric pad, providing an average
20 mA over 48 hours, and the CK level differences
were significantly lower in the treated group 4–7 days
after injury.
151
Drawing firm conclusions from these human
studies is hampered by various factors. In particular,
the use of proprietary devices delivering microcurrent
whose parameters are based on little if any scientific
rationale. The outcome measures they adopt often
give only indirect information about tissue status,
and some studies are poorly constructed or reported.
Nevertheless they suggest that MCT may have
potential in promoting the resolution of various
musculoskeletal soft tissue disorders, and indicate the
need for well-conducted clinical trials. The normally
sub-sensory nature of microcurrent means that
double-blind placebo-controlled trials, which could
provide convincing evidence, are practicable.
However, at least for the present, the most persuasive
evidence in favour of MCT for soft tissue lesions is
provided by cellular and animal studies.
Conclusions
The evidence in support of MCT is convincing
enough to justify its inclusion in the clinician’s
repertoire for treatment of several examples of
recalcitrant bone and skin lesions. Indeed federal
and private health insurance providers in the USA
have accepted its use (along with other forms of
Poltawski and Watson Bioelectricity and microcurrent therapy for tissue healing
110 Physical Therapy Reviews 2009 VOL 14 NO 2
electrical stimulation) for spinal fusions and hard to
heal skin ulcers for some years.
53,83
In contrast, the
lack of substantial and robust human trial evidence
for the use of MCT with musculoskeletal soft tissue
lesions is frustrating. Clinicians are justifiably cau-
tious when presented with yet another form of
electrotherapy, especially when the case for those
that are more familiar and well-used, such as
therapeutic ultrasound, has been questioned in
several reviews.
155–157
Yet MCT has several significant features in its
favour: there is already substantial evidence that it
can promote healing in a variety of tissue types and
disorders, especially where other approaches have
failed; it may help redress an underlying physiological
dysfunction as well as reducing its symptoms; its
mechanism of action appears to be as a trigger or
facilitator of the whole healing process, unlike some
new approaches such as exogenous growth factors,
which have specific targets in the healing cascade.
Reported side-effects of MCT are few and minor, and
it can be provided by a small, portable generator,
over an extended period where necessary, requiring
minimal therapist supervision once initiated. The
therapy has been shown to be most beneficial when it
is used as part of a broader management strategy.
Given these characteristics, the potential for MCT in
a range of recalcitrant musculoskeletal disorders is
worthy of closer attention by both research and
clinical communities.
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LEON POLTAWSKI
School of Health and Emergency Professions, University of Hertfordshire, Hatfield, AL10 9AB, UK
Tel: z44 1707 284968; Email: L.Poltawski@herts.ac.uk
Poltawski and Watson Bioelectricity and microcurrent therapy for tissue healing
114 Physical Therapy Reviews 2009 VOL 14 NO 2
... Microcurrent therapy remains a relatively obscure modality and is unfamiliar to many clinicians. 5 This may in part be due to the mixed evidence of its effectiveness, with studies using some forms of microcurrent therapy failing to find evidence of its use for pain relief. [5][6][7][8][9] Others observe studies having methodological shortcomings. ...
... 5 This may in part be due to the mixed evidence of its effectiveness, with studies using some forms of microcurrent therapy failing to find evidence of its use for pain relief. [5][6][7][8][9] Others observe studies having methodological shortcomings. 5,10 While others report a significant reduction in pain using microcurrent therapy. ...
... [5][6][7][8][9] Others observe studies having methodological shortcomings. 5,10 While others report a significant reduction in pain using microcurrent therapy. 5,11 The mechanism of pain control using a microcurrent therapy device, also called microtens device, differs from traditional transcutaneous nerve stimulation using nerve excitation by sensory stimulation. ...
Article
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Objective We would like to determine whether electrotherapy, specifically microcurrent therapy, increases function and decreases pain in people who have acute knee pain. Design Randomized, double-blinded, placebo-controlled clinical trial. Setting University laboratory and patient home. Subjects A total of 52 subjects (35 females and 17 males) with acute knee pain. Intervention Treatment group ( n = 26) wore the active microcurrent therapy device at home for 3 hours per day for 4 weeks and the control group ( n = 26) wore the placebo for 3 hours per day for 4 weeks. Main Measures Numeric Pain Rating Scale (NPRS) and Short Form 12 (SF-12) health scale were used to measure the pain level and the functionality of the participants. Secondary assessments included musculoskeletal ultrasound imaging (MSK US) and Lower Extremity Functional Scale (LEFS). Results A total of 52 subjects completed the study; 26 in the treatment group and 26 in the control group. Microcurrent therapy significantly reduced pain over 4 weeks. Especially week three was significant ( P < 0.01) after adjusting for the family-wise error rate. The analysis on SF-12 revealed those with microcurrent therapy showed an increasing trend in the improvement of physical function score until week three. Conclusion An active microcurrent therapy device decreased knee pain and increased function. Microcurrent therapy may be an alternative or used with a pharmacological approach for people with acute knee pain.
... It is a method of stimulating the tissues beneath the skin surface using very high frequency sound waves, between 800,000 Hz and 2,000,000 Hz. Microcurrent therapy (MCT) involves the direct application of electric currents in the microampere (μA) range to the body for therapeutic purposes [8][9][10][11][12][13][14]. It uses current in the micro ampere range, 1000 times less than that of TENS and below sensation threshold. ...
Article
Background: Lateral epicondylitis is a relatively common musculoskeletal condition that can cause significant pain and disability. Treatment of lateral epicondylitis aims at reducing pain, increasing grip strength and improving the quality of life of the patient. Therapeutic ultrasound, phonophoresis, LASER therapy, manipulation, soft tissue mobilisation, neural tension, stretching and strengthening has long played an important role in the treatment of lateral epicondylitis, however treatment involving Microcurrent therapy for management of lateral epicondylitis are limited to this date. Objective: To compare the effectiveness of Ultrasound therapy and Microcurrent therapy in subjects with chronic lateral epicondylitis. Study design: Quasi experimental study design. Subjects: 20 subjects, 10 each with Ultrasound therapy and Microcurrent therapy age group between 35-50 years of both male and female. Intervention: 10 subjects in group A received Ultrasound therapy with Pre and Post-test and 10 subjects in group B received Microcurrent therapy with Pre and post-test. Outcome measure: Visual Analogue Scale [VAS], Grip Strength and PRTEE Results: Statistical analysis was done by using paired ‘t’ test which showed significant improvement in both groups. Conclusion: Microcurrent therapy has shown significant result in reduction of pain, increased grip strength and functional activity in patients with chronic lateral epicondylitis.
... Given the potential benefits of microcurrent to optimise cellular energy production (Poltawski & Watson, 2009) and muscular function (Hiroshige et al., 2018), the primary outcome measure was focused on assessing the change in endurance performance. Additionally, considering the effects of microcurrent treatments on lipolysis, enhancing the exercise induced adipose tissue decrease (Noites et al., 2015), promoting muscle mass accretion (Naclerio et al., 2019), hastening recovery and reducing markers of muscle damage (Udani, Singh, Singh, & Sandoval, 2009), secondary outcome measures included changes in body composition, post-exercise lactate concentration and the perception of muscular soreness. ...
Article
Post-exercise microcurrent based treatments have shown to optimise exercise-induced adaptations in athletes. We compared the effects of endurance training in combination with either, a microcurrent or a sham treatment, on endurance performance. Additionally, changes in body composition, post-exercise lactate kinetics and perceived delayed onset of muscle soreness (DOMS) were determined. Eighteen males (32.8±6.3 years) completed an 8-week endurance training programme involving 5 to 6 workouts per week wearing a microcurrent (MIC, n=9) or a sham (SH, n=9) device for 3-h post-workout or in the morning during non-training days. Measurements were conducted at pre- and post-intervention. Compared to baseline, both groups increased (P<0.01) maximal aerobic speed (MIC, pre =17.6±1.3 to post=18.3±1.0; SH, pre=17.8±1.5 to post =18.3±1.3 km.h⁻¹) with no changes in O2peak. No interaction effect per group and time was observed (P=0.193). Although both groups increased (P<0.05) trunk lean mass (MIC, pre=23.2±2.7 to post=24.2±2.0; SH, pre=23.4±1.7 to post=24.3±1.6 kg) only MIC decreased (pre=4.8±1.5 to post=4.5±1.5, p=0.029) lower body fat. At post-intervention, no main differences between groups were observed for lactate kinetics over the 5 min recovery period. Only MIC decreased (P<0.05) DOMS at 24-h and 48-h, showing a significant average lower DOMS score over 72-h after the completion of the exercise-induced muscle soreness protocol. In conclusion, a 3-h daily application of microcurrent over an 8-week endurance training programme produced no further benefits on performance in endurance-trained males. Nonetheless, the post-workout microcurrent application promoted more desirable changes in body composition and attenuated the perception of DOMS over 72-h post-exercise. Trial registration: ClinicalTrials.gov identifier: NCT03477747..
... It is believed that different amplitudes can be used, as long as they do not exceed 1000μA and are in a tolerable range for the patient at the wound site (19) . Cheng et al. (46) demonstrated that the therapeutic range is located between 10 to 1000μA for the skin of rats, with the greatest increase in the incorporation of glycine and aminoisobutyric acid in the skin protein, in relation to the control group, occurred in the intensity of 500μA (123% and 90% increase, respectively). ...
Article
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Background: High-intensity interval training promotes body weight loss, while microcurrent electrical stimulation has therapeutic potential toreduce localized abdominal fat. However, there are no studies that have investigated the association of the two forms of intervention in reducinglocalized adiposity. Objectives: To verify the effects of high-intensity interval training, associated or not, with microcurrent therapy, in reducinglocalized abdominal fat. Methods: A randomized controlled clinical study will be conducted with 60 women aged 18 to 40 years, with localizedabdominal adiposity. Participants will be randomized into 3 groups: Control Group (without physiotherapeutic intervention), Exercise Group(high-intensity interval training for 30 minutes) and Exercise Group associated with Microcurrent (application of 30 minutes of microcurrent priorto high-intensity interval training). The intervention will take place twice a week for 5 weeks. The clinical outcomes evaluated and their respectivemeasuring instruments will be: body composition (bioimpedance scale and adipometry), anthropometric measurements (perimetry), level ofphysical activity (International Physical Activity Questionnaire - IPAQ, short version), quality of life (IWQol-Lite, short version), body satisfaction(Stunkard figure rating scale), degree of satisfaction with the performance of the intervention (questionnaire adapted by the researchers) andevaluation of the lumbopelvic complex. These outcomes will be measured in 4 moments: before the intervention, after the 5th and 10thintervention, and with a follow-up of 1 month. Discussion: A previous study has already shown the positive result of the association of moderateintensity exercise, associated with the previous application of microcurrent, in reducing localized abdominal adiposity. These findings raised thehypothesis that the association of this electrical therapy with high-intensity interval training may present positive results in the search for thereduction of abdominal fat, with the clinical advantage of enhancing the achieved results and/or reducing the time spent by the patient in therapy.
Article
Cells in vivo are situated in a complicated microenvironment composed of diverse biochemical and biophysical cues. To regulate biological functions of cells, tissues and organs bioelectricity (i.e., electrical cues) plays a particularly important role. Along with the development of tissue engineering and regenerative medicine (TERM), the positive effects of bioelectricity on the regeneration of excitable tissues have been well recognized through promoting cell proliferation, differentiation and migration and tissue functionalities. Conductive biomaterials have emerged as enabling tools to improve the outcomes of excitable tissue regeneration by facilitating the transmission of endogenous bioelectricity or electrical stimulation to electrically-isolated cells and tissues. Moreover, advanced electrical functionalities of conductive biomaterials can realize more controllable and smart TERM approaches. In this review, conductive biomaterials employed for TERM applications are comprehensively reviewed. First, the biological basis underlying the function of conductive biomaterials is introduced. Second, rational design strategies for conductive biomaterials displaying favorable microenvironmental cues (e.g., electrical, mechanical, structural) and electrical functionalities are summarized from the aspects of conductive and nonconductive components, biomaterial formats, spatial distribution of components, and anisotropy. Subsequently, strategies for the application of conductive biomaterials in TERM of excitable tissues, including nerves, myocardium, skeleton muscles, bones and skin/wounds, are reviewed. Finally, the future perspectives of conductive biomaterials for TERM applications are given.
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Objective To summarize the level of knowledge regarding the effects of microcurrent therapy (MCT) on musculoskeletal pain in adults. Data Sources The PubMed, Physiotherapy Evidence Database, Cumulative Index to Nursing Allied Health Literature, and Cochrane Central Register of Controlled Trials, and Igaku Chuo Zasshi database were searched from the time of their inception to December 2020. Study Selection Randomized controlled trials (RCTs) investigating the effects of MCT on musculoskeletal pain were included. Additionally, non-RCTs were included to assess the adverse events. Data Extraction The primary outcomes were pain and adverse events related to MCT. To assess the reproducibility of MCT, we evaluated the completeness of treatment description using the Template for Intervention Description and Replication (TIDieR) checklist. We also assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Data Synthesis A comprehensive assessment of four RCTs and five non-RCTs that met the inclusion criteria revealed that MCT significantly improved shoulder pain (one study, 40 patients) and knee pain (one study, 52 patients) compared to sham MCT without any severe adverse events. MCT has clinically significant benefits for knee pain. This study also revealed a clinically significant placebo response in treating knee pain. This evidence highlights the substantial impact of placebo response in clinical care. These treatment effects on knee pain are further supported by the high quality of evidence in GRADE with high reproducibility in TIDieR. Conclusions The findings of this meta-analysis highlight the impact of placebo response in treating knee pain. MCT is a potential, core non-pharmacological treatment option in clinical care with minimal adverse events and should be further investigated. This study proposes a framework for the future investigation of the effect of MCT on musculoskeletal pain to enhance the study quality and reproducibility.
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Diabetes mellitus (DM) is a major metabolic disorder and an increasing health problem worldwide. Effective non-invasive therapies for DM are still lacking. Here, we have developed Microcurrent electrical nerve stimulation (MENS), a non-invasive therapy, and tested on 46 mice clustered into five groups, such as control, STZ-induced DM, and MENS treatment groups. Experimental results show that MENS treatment is able to improve seven biochemical indexes (e.g., hemoglobin A1c and glucose level). To investigate the mechanisms of MENS treatment on STZ-induced DM, we selected six representative samples to perform microarray experiments for several groups and developed an integrated Hierarchical System Biology Model (HiSBiM) to analyze these omics data. The results indicate that MENS can affect fatty acid metabolism pathways, peroxisome proliferator-activated receptor (PPAR) signaling pathway and cell cycle. Additionally, the DM biochemical indexes and omics data profiles of MENS treatment were found to be consistent. We then compared the therapeutic effects of MENS with anti-diabetic compounds (e.g., quercetin, metformin, and rosiglitazone), using the HiSBiM four-level biological functions and processes of multiple omics data. The results show MENS and these anti-diabetic compounds have similar effect pathways highly correlated to the diabetes processes, such as the PPAR signaling pathway, bile secretion, and insulin signaling pathways. We believe that MENS is an effective and non-invasive therapy for DM and our HiSBiM is an useful method for investigating multiple omics data.
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Recently, a variety of safe and effective non-pharmacological methods have been introduced as new treatments of alopecia. Micro-current electrical stimulation (MCS) is one of them. It is generally known to facilitate cell proliferation and differentiation and promote cell migration and ATP synthesis. This study aimed to investigate the hair growth-promoting effect of MCS on human hair follicle-derived papilla cells (HFDPC) and a telogenic mice model. We examined changes in cell proliferation, migration, and cell cycle progression with MCS-applied HFDPC. The changes of expression of the cell cycle regulatory proteins, molecules related to the PI3K/AKT/mTOR/Fox01 pathway and Wnt/β-catenin pathway were also examined by immunoblotting. Subsequently, we evaluated the various growth factors in developing hair follicles by RT-PCR in MCS-applied (MCS) mice model. From the results, the MCS-applied groups with specific levels showed effects on HFDPC proliferation and migration and promoted cell cycle progression and the expression of cell cycle-related proteins. Moreover, these levels significantly activated the Wnt/β-catenin pathway and PI3K/AKT/mTOR/Fox01 pathway. Various growth factors in developing hair follicles, including Wnts, FGFs, IGF-1, and VEGF-B except for VEGF-A, significantly increased in MCS-applied mice. Our results may confirm that MCS has hair growth-promoting effect on HFDPC as well as telogenic mice model, suggesting a potential treatment strategy for alopecia.
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Werner, Sabine, and Richard Grose. Regulation of Wound Healing by Growth Factors and Cytokines. Physiol Rev 83: 835–870, 2003; 10.1152/physrev.00032.2002.—Cutaneous wound healing is a complex process involving blood clotting, inflammation, new tissue formation, and finally tissue remodeling. It is well described at the histological level, but the genes that regulate skin repair have only partially been identified. Many experimental and clinical studies have demonstrated varied, but in most cases beneficial, effects of exogenous growth factors on the healing process. However, the roles played by endogenous growth factors have remained largely unclear. Initial approaches at addressing this question focused on the expression analysis of various growth factors, cytokines, and their receptors in different wound models, with first functional data being obtained by applying neutralizing antibodies to wounds. During the past few years, the availability of genetically modified mice has allowed elucidation of the function of various genes in the healing process, and these studies have shed light onto the role of growth factors, cytokines, and their downstream effectors in wound repair. This review summarizes the results of expression studies that have been performed in rodents, pigs, and humans to localize growth factors and their receptors in skin wounds. Most importantly, we also report on genetic studies addressing the functions of endogenous growth factors in the wound repair process.
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This paper presents a quantitative synthesis of the literature addressing the effectiveness of ultrasound in selected musculoskeletal conditions. Pain and range of motion appear to improve following ultrasound treatment in acute periarticular inflammatory conditions and osteoarthritis, but not in chronic periarticular inflammatory conditions. Placebo response and experimenter expectancy bias can not be ruled out as explanations for the positive results. The literature concerning the therapeutic efficacy of ultrasound for pain and immobility in musculoskeletal conditions is therefore inconclusive. Well-designed clinical trials are needed to resolve this question.
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The social, economical and psychological importance of hand injuries has stimulated a great deal of interest in tendon repair and healing. The search for earlier, stronger, and organized healing free of restricting scar tissue continues. Recent investigations in the application of electric current to dermal wounds seems promising. In addition, the electrophysiology of collagen and tendon has been further defined as to piezoelectricity and pyroelectricity. A need for in vivo determinations was apparent, as well as the application of electric current to the healing of a collagenous structure such as tendon. In tests on dogs it was observed that the resting potential is maximal in the intact tendon, falls toward zero when the tendon is severed and eventually returns toward the intact level. This might be correlated with tendon healing and return of strength, and thus serve as a guide for initiating rehabilitation.
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The risk of nonunion in both the ankle and subtalar joints has been reported as high as 41% and 16%, respectively. Several factors have been reported to significantly Increase the incidence of nonunion: smoking, previous nonunion, osteonecrosis, history of infection, fracture type, and major medical problems. A single surgeon's experience is retrospectively reviewed. Thirteen patients who were identified as high risk for non-union had an Implantable electrical stimulator placed at the time of their ankle or hindfoot fusion along with bone grafting. Three ankle, two subtalar, six tiblotalocalcaneal, and two tiblocalcaneal fusions were performed. All 13 patients had a minimum of two major risk factors for non-union. Of the 13 patients, 11 were active smokers and five of 13 had three or more major risk factors. At a minimum of one year follow-up (average, 24.6 months), successful fusion was achieved In 12 of 13 (92%) patients. Pain scores improved from a mean of 8.5 points preoperatively (range, 7 to 10) to a mean of 1.9 points postoperatively (range, 1 to 6), while the preoperative mean modified AOFAS score of 31.2 points (range, 15 to 55) improved to 85.4 points (range, 45 to 100) postoperatively. The improvement was statistically significant at p<0.01. Eleven of 13 patients (85%) ranked their pain as a I or 2 out of 10, and achieved a modified AOFAS score of 80 or better. No additional procedures were done to achieve fusion. Four patients developed superficial wound infections requiring local wound care. The subcutaneous battery pack was bothersome to eight of 13 patients, painful to one, and removed in four patients. The results suggest that electrical implantable stimulation may be a useful adjunct to rigid internal fixation and bone grafting for ankle and hindfoot fusions in high-risk patients.