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Clinical results after ultrasound-guided intratissue percutaneous
electrolysis (EPI
Ò
) and eccentric exercise in the treatment
of patellar tendinopathy
F. Abat •P. E. Gelber •F. Polidori •
J. C. Monllau •J. M. Sanchez-Iban
˜ez
Received: 15 September 2013 / Accepted: 12 January 2014
ÓSpringer-Verlag Berlin Heidelberg 2014
Abstract
Purpose To investigate the outcome of ultrasound (US)-
guided intratissue percutaneous electrolysis (EPI
Ò
) and
eccentric exercise in the treatment of patellar tendinopathy
during a long-term follow-up.
Methods Forty patients with patellar tendinopathy were
prospectively evaluated over a 10-year follow-up period.
Pain and function were evaluated before treatment, at
3 months and at 2, 5 and 10 years using the Victorian
Institute of Sport Assessment–Patella (VISA-P) score, the
Tegner score and Blazina’s classification. According to
VISA-P score at baseline, patients were also dichotomized
into Group 1 (\50 points) and Group 2 (C50 points). There
were 21 patients in Group 1 and 19 in Group 2. Patient
satisfaction was measured according to the Roles and
Maudsley score.
Results The VISA-P score improved globally by 41.2
points (p\0.01) after a mean 4.1 procedures. In Group 1,
VISA-P score improved from 33.1 ±13 to 78.9 ±14.4 at
3-month and to 88.8 ±10.1 at 10-year follow-up
(p\0.001). In Group 2, VISA-P score improved from
69.3 ±10.5 to 84.9 ±9 at 3-month and to 96.0 ±4.3 at
10-year follow-up (p\0.001). After 10 years, 91.2 % of
the patients had a VISA-P score[80 points. The same level
(80 % of patients) or the Tegner score at no more than one
level lower (20 % of patients) was restored, and 97.5 % of
the patients were satisfied with the procedure.
Conclusion Treatment with the US-guided EPI
Ò
tech-
nique and eccentric exercises in patellar tendinopathy
resulted in a great improvement in knee function and a
rapid return to the previous level of activity after few
sessions. The procedure has proved to be safe with no
recurrences on a long-term basis.
Level of evidence Therapeutic study, Level IV.
Keywords Intratissue percutaneous electrolysis EPI
Eccentric exercises
Introduction
Patellar tendinopathy or jumper’s knee is a frequent con-
dition that most commonly affects the tendon’s origin on
the inferior pole of the patella [2,4,10]. Once considered
an inflammatory condition, it is currently considered a
degenerative process due to the presence of myxoid
degeneration, the disruption of the collagen fibres and signs
of hypoxia in tenocytes and resident macrophages [6,17].
The overall prevalence of patellar tendinopathy is
around 14 % in the sports population [3,16], but may be as
high as 40 % in highly demanding athletes [8]. The ten-
don’s overuse in sports that involve running, jumping or
rapid change in direction is considered the main risk factor
for developing the said condition [16].
Current treatment options include eccentric training [15,
18,29], open or arthroscopic surgery, extracorporeal
shockwave therapy [25], ultrasound (US)-guided sclerosis
[12], non-steroidal anti-inflammatory drugs, platelet-rich
F. Abat (&)F. Polidori J. M. Sanchez-Iban
˜ez
CEREDE-Sports Medicine, Dr. Roux 8-10, 08017 Barcelona,
Spain
e-mail: FERRANABAT@GMAIL.COM; drabat@cerede.es
P. E. Gelber J. C. Monllau
Department of Orthopedic Surgery, Hospital de la Santa Creu i
Sant Pau, Universitat Auto
`noma de Barcelona, Barcelona, Spain
P. E. Gelber J. C. Monllau
ICATME-Hospital Universitari Quiro
´n Dexeus, Universitat
Auto
`noma de Barcelona, Barcelona, Spain
123
Knee Surg Sports Traumatol Arthrosc
DOI 10.1007/s00167-014-2855-2
plasma injection [30] and aprotinin [1]. These studies have
also suggested that, in general, patients with a worse
functional status before treatment obtain inferior final
outcomes. However, due to the limited evidence-based
therapies, there are still several controversies regarding the
real efficacy of these treatment modalities [1].
Intratissue percutaneous electrolysis (EPI
Ò
) treatment is
a pioneering US-guided technique developed by one of the
authors. It leads to a non-thermal electrochemical ablation
through a cathodic flow directly at the clinical focus of
degeneration. EPI
Ò
causes an organic reaction leading to a
highly localized inflammation, exclusively at the region of
treatment that conduces to a rapid regeneration of the
injured tendon [26].
The present study provides the first analysis of the
results of EPI
Ò
in the treatment of patellar tendinopathy at
10 years follow-up. This study could be clinically relevant
given the lack of effective techniques in the treatment of
patellar tendinopathy.
The aim of this study was to investigate the outcome of
the US-guided EPI
Ò
technique in terms of pain, function
and the return to the previous level of activity in patients
with patellar tendinopathy. The mean follow-up of
10 years provides information on safety and the rate of
recurrence. The main hypothesis was that the US-guided
EPI
Ò
technique would quickly improve the outcome in
patients with patellar tendinopathy and that this improve-
ment would be maintained over a long period of time. The
second hypothesis was that good outcomes would be
obtained regardless of the initial degree of functional
impairment. It was also hypothesized that the patients
would be restored to their pre-injury activity level.
Materials and methods
From January 2002 to October 2002, 41 patients with
patellar tendinopathy were included in the investigation.
Demographic data and patient information (age, gender,
affected and dominant side, kind of sport or activity level)
were recorded.
The inclusion criteria were a history of patellar tendon
pain, tenderness upon palpation, functional limitation
directly related to the studied tendon and sonographic
confirmation of tendon degeneration. A tendon injury
located at the inferior pole of the patella was considered a
requisite. Other inclusion criteria were more than 4 weeks
of symptoms and an age of \60 years old. Patients were
classified according to Blazina’s scale [22]. Exclusion
criteria were pain at the proximal pole of the patella (fre-
quently included in jumper’s knee), chronic articular dis-
ease, a concomitant knee pathology, contraindications to
the EPI
Ò
technique and the concomitant administration of
certain drugs (at least 2 weeks before receiving treatment).
The inclusion and exclusion criteria are summarized in
Table 1.
Ultrasound examination
All the patients went through an exhaustive US examina-
tion of the tendon and adjacent structures using a high-
resolution greyscale US (Fig. 1) with Doppler power and
linear multi-frequency probe (6–15 MHz). The injured and
the contralateral knees were studied in all patient. The US
efficacy for the proper diagnosis of patellar tendinopathy
was previously reported [11,36,37].
Intratissue percutaneous electrolysis (EPI
Ò
) protocol
The EPI
Ò
technique was applied using a specifically
developed medically certified (Directive 93/42/EEC)
device (EPI Advanced Medicine, Barcelona, Spain), which
produces modulated galvanic electricity through the neg-
ative electrode cathodic flow. This is applied using a
modified electrosurgical scalpel that uses acupuncture
needles (0.3 mm in diameter) with different lengths. The
intensity can be adjusted by changing the duration or the
milliamps of the device. Conversely, the polarity of the
machine is fixed (i.e. only the cathodic flow is usable).
During the procedure, performed by the same experienced
operator, the patients are supine so as to minimize any
potential vagal reaction.
Isopropyl alcohol was used to prepare the skin despite
the bacteriostatic action of the EPI
Ò
system. Polyvidone
iodine was avoided to prevent a tattoo effect of the
Table 1 Inclusion and exclusion criteria
Inclusion criteria Exclusion criteria
\60 years old Chronic articular disease
History of patellar tendon pain
[4 weeks
Concomitant knee pathology (e.g.
cruciate ligament injury of
meniscal tear)
Tenderness to palpation Contraindications of EPI
Ò
technique
(i.e. pregnancy, knee prosthesis,
osteosynthesis, cardiac disease,
malign tumour or coagulopathy)
Functional limitation directly
related to the tendon injury
Concomitant administration of drug
(i.e. fluoroquinolones,
anticoagulants, corticosteroids or
non-steroidal anti-inflammatory
Sonographic confirmation of
tendon degeneration
Injury located at the inferior
pole of the patella
Blazina’s
classification Cgrade I
Knee Surg Sports Traumatol Arthrosc
123
cathodic flow. Finally, three US-guided precise punctures
at 3 mA (Fig. 2) were performed until a complete
debridement of the treated area was obtained. The
debridement was assessed with the sonographic images.
After the first EPI
Ò
treatment, the patients underwent
consecutive sessions of EPI
Ò
every 2 weeks and 2 weekly
sessions of an eccentric exercise training using the resis-
tance isoinertial leg-press machine (YoYo
TM
Technology
AB, Stockholm, Sweden). Eccentric exercises were per-
formed in three sets of ten repetitions twice a week in order
to obtain maturation of collagen fibres [24,31]. Each
repetition was performed with the concentric phase with
both extremities, whereas the eccentric phase was only
performed with the affected limb at a maximum of 60°of
knee flexion.
Patients received US-guided EPI
Ò
treatment up to a
maximum of ten sessions. The treatment finished either
when the patients were symptom free or if there was no
improvement in terms of pain or function after those ten
sessions.
Treatment evaluation
All the patients were evaluated before treatment and pro-
spectively when their treatments were finished (at the third
month), at 2-year, at 5-year and at 10-year follow-up.
The primary outcome measure was knee function using
the Victorian Institute of Sport Assessment–Patella (VISA-P)
score, a specific validated questionnaire to quantify pain
and knee function and ability to play sport in patients with
patellar tendinopathy [9,34]. The VISA-P score ranged
from a maximum of 100 in asymptomatic patients to the
theoretical minimum of 0. The authors of the score sug-
gested that a score between 80 and 100 points might be
considered as the optimal outcome category. Functional
evaluation was further assessed with Blazina’s classifica-
tion [22]. This classification categorizes the symptomatic
patients as in phase I (pain only after activity), phase II
(discomfort during activity), phase III (pain during activity
that interferes with participation) and phase IV (complete
tendon disruption). The Tegner score was also used to
assess the influence of the treatment in terms of restoring
the previous sports activity level. All the written ques-
tionnaires were personally filled out by all patient before
treatment, at the end of the treatment (at 3-month) and at
the 2-year follow-up. The questionnaires corresponding to
the 5- and 10-year follow-up evaluations were all filled out
through a telephone interview. Patient satisfaction was
Fig. 1 High-resolution colour
Doppler ultrasound of patellar
tendinopathy. aLongitudinal
and btransversal views of the
involved tendon showing a high
degree of neovascularization
before the EPI
Ò
treatment. The
same patient 3 months after
initiation of the EPI
Ò
procedures had a remarkable
decrease in the vascularization
of the patellar tendon clearly
seen in these longitudinal
(c) and transversal (d) views
Fig. 2 Intratissue percutaneous electrolysis (EPI
Ò
) procedure. The
0.3-mm needle (Asterisks) is being guided by high-resolution
greyscale ultrasound to puncture the injured region of the tendon
Knee Surg Sports Traumatol Arthrosc
123
measured according to the Roles and Maudsley score [23].
In this score, patients are classified as Excellent (no pain,
full movement and full activity), Good (occasional dis-
comfort, full movement and full activity), Fair (some
discomfort after prolonged activity) or Poor (pain limiting
activities).
All those patients that scored\50 points with the VISA-
P questionnaire at baseline were denominated Group 1,
whereas the remaining patients scoring equal to or higher
than 50 points were denominated Group 2. This classifi-
cation allows to display the results in different degrees of
injury of the patellar tendon: more (VISA-P \50 points)
or less affected (VISA-P [50 points).
The Clinical Research Ethics Committee of ICATME-
Institut Universitari Dexeus, University of Barcelona,
approved the study (09/06/0049). All the patients signed
informed consent to participate in the study as well as for
the evaluation and publication of their results.
Statistical analysis
Categorical variables are presented as number of cases and
percentages. Continuous variables are presented as
mean ±SD (range). The relationships between categorical
variables were described using contingency tables, and
inference was studied using the chi-square test or Fisher’s
exact test. The relation between the VISA-P score and
dichotomous variables was assessed using the Mann–
Whitney test, showing the median value. Analysis of var-
iance (ANOVA) was used to compare the evolution
between groups. Statistical significance was set at 0.05
two-sided. Statistical analysis was performed using SPSS
19 (SPSS Inc., Chicago, IL, USA).
Results
One patient was lost during the first 3 months of follow-up.
The remaining 40 patients were available at the 3-month
and at the 2-year evaluations. At the 5-year evaluation,
another three patients were lost (37 patients available,
90.2 % of the cases) and another three patients at the
10-year assessment (34 patients available, 82.9 % of the
cases).
Patient description
Twenty-one patients (52.5 %) were included in Group 1
and the remaining 19 (47.5 %) in Group 2. Both groups
were comparable in terms of age, gender, side and func-
tional scores at baseline (Table 2). Sports involvement is
summarized in Table 3. No relation (n.s.) between the
injured tendon and the dominant extremity, the type of
sport, the age of the patient and gender, and the VISA-P
values obtained after the treatments was observed.
The mean duration of symptoms prior to the treatment was
69.4 ±65.6 weeks (range 4–288 weeks). The athletes were
off sports activities due to their patellar tendinopathy for a
mean time of 40.6 ±50.9 weeks (range 0–192 weeks).
Treatment duration averaged 7.5 ±2.6 weeks (range
1–10 weeks), and the patients required a mean of 4.1 ±2.6
EPI
Ò
procedures (range 1–10). According to Blazina’s
classification, one patient (2.5 %) was of stage I at baseline,
seven patients (17.5 %) stage II and the remaining 32
patients (80 %) stage III. At the 3-month evaluation, once all
the treatments were finished, five patients (12.5 %) were
classified as of stage I and six patients (15 %) stage II. All the
remaining 30 cases (72.5 %) were considered completely
cured (less than Blazina’s stage I). At the 2-year follow-up
evaluation, 31 cases (77.5 %) were asymptomatic (less than
Blazina’s stage I) and nine (22.5 %) were in stage I. Analysis
Table 2 Patient characteristics at baseline
Group 1 n=21
(52.5 %)
Group 2 n=19
(47.5 %)
pvalue
Age (years)
Mean ±SD 26.0 ±8.49 25.7 ±8.12 n.s.
Gender % (n)
Male 81.0 (17) 94.7 (18) n.s.
Female 19.0 (4) 5.3 (1)
Dominant extremity % (n)
Right 81.0 (17) 89.5 (17) n.s.
Left 19.0 (4) 10.5 (2)
Injured knee % (n)
Right 38.1 (8) 15.8 (3) n.s.
Left 47.6 (10) 68.4 (13)
Bilateral 14.3 (3) 15.8 (3)
Baseline VISA-P
Mean ±SD 32.5 ±12 69.5 ±10.05 \0.001
Values expressed as mean ±SD or frequencies and percentages
Table 3 Patient sports involvement at baseline
Series n=40
Blazina’s stage
Median (range) 3 (2–3)
Sports type % (n)
Soccer 60 (24)
Other 40 (16)
Sports level % (n)
Professional (first division) 12.5 (5)
Semi-professional (second division or similar) 67.5 (27)
Recreational 20 (8)
Values expressed as mean ±SD or frequencies and percentages
Knee Surg Sports Traumatol Arthrosc
123
of the patients using the Blazina’s classification remained
unchanged throughout the remaining follow-up evaluations
of the period studied (n.s.).
Clinical outcomes over time
The VISA-P (Fig. 3) and Tegner scores before treatment, at
3 months and at 2, 5 and 10 years of follow-up are sum-
marized in Table 4. Group 1 improved by 45.8 points
(p\0.001) at 3 months to obtain a mean VISA-P score of
78.9 ±14.4. In Group 2, the mean improvement in VISA-
P score at 3 months was 15.6 points at 3 months
(p\0.001). The Tegner level did not drop over the
10 years of the study period, and no differences between
the intermediate evaluations (n.s.) were observed either.
According to the Roles and Maudsley score, patient
satisfaction at 3 months of follow-up was considered
Excellent in 32 cases (80 %), Good in seven cases (17.5 %)
and Fair in one case (2.5 %). These values persisted
without significant differences throughout the period
studied. No recurrences, adverse episodes or any additional
modality of treatments were reported after the 10 years of
follow-up.
At the 3-month follow-up evaluation, 32 (80 %) patients
restored their previous activity level according to Tegner
scale (n.s.). In eight patients (20 %), there was a decrease
in only one single level on the same scale. These values
were maintained over the remaining period studied (n.s.).
Discussion
Treatment with EPI
Ò
in combination with eccentric exer-
cises has been shown to effectively improve the symptoms
of patellar tendinopathy quickly and steadily for at least
10 years. It confirmed the first hypothesis. This improve-
ment in patients that had different severities of VISA-P
scores at baseline was equally obtained in terms of symp-
tomatology, knee function and return to sports activity,
which is also in concordance with the second hypothesis.
The results observed in the first study reporting on the
clinical use of EPI
Ò
are encouraging [26]. Its effects are
based on a local and non-thermal electrochemical therapy
that induces a localized short inflammatory response
through an electrolytic reaction produced by a cathodic
flow. Consequently, this causes an organic reaction leading
to the regeneration of the injured tendon [26].
Conservative treatment was traditionally considered the
first option of treatment of tendinopathies. Many different
techniques were used [1,8], such as modification of
activity, eccentric physical training, patellar straps, cold
and heat compression transfriction massage and stretching
for quadriceps, hamstrings and patellar tendons. Despite
some good results reported with eccentric programmes [18,
28], it is still unclear as to the more effective exercise
protocol, its frequency, load and dosage. While Zwerver
et al. [37], in a recent randomized clinical trial, concluded
that no benefit came of extracorporeal high-energy shock-
wave therapy during competition, Rompe et al. [25]
reported, at 4-month follow-up, that eccentric loading
Fig. 3 Linear diagram of the mean Victorian Institute of Sport
Assessment–Patella (VISA-P) scores for Group 1, Group 2 and all the
patients (Global) at baseline (Initial), at 3 months and at 2, 5 and
10 years
Table 4 Victorian Institute of Sport Assessment–Patella (VISA-P) values during follow-up
Time VISA-P score Tegner score
Group 1 Group 2 Global Group 1 Group 2 Global
Baseline (n=40) 33.1 (±13) 69.3 (±10.5) 51.2 (±21.7) 8.1 (6–10) 7.8 (4–9) 7.9 (4–10)
3 months (n=40) 78.9* (±14.4) 84.9* (±9) 81.9* (±12.2) 7.7 (4–10) 7.6 (3–9) 7.7 (3–10)
2 years (n=40) 83.2 (±13.6) 88.6 (±7.4) 85.9 (±11.1) 8.1 (5–10) 7.7 (4–9) 7.8 (4–10)
5 years (n=37) 85.2 (±12.2) 91.9 (±5.6) 88.6 (±10) 7.9 (5–10) 7.6 (4–9) 7.8 (4–10)
10 years (n=34) 88.8 (±10.1) 96.0 (±4.3) 92.4 (±8.5) 7.7 (5–10) 7.3 (4–9) 7.5 (4–10)
Victorian Institute of Sport Assessment–Patella (VISA-P) values expressed as mean (±SD). Tegner values are expressed as median (range)
*p\0.001. No statistically significant differences were observed in the results between any intermediate outcome measurements other than
from baseline
Knee Surg Sports Traumatol Arthrosc
123
alone was less effective when compared with a combina-
tion of eccentric loading and repetitive low-energy shock-
wave treatment. Similarly, low-intensity US is not
currently considered a reliable method for the treatment of
patellar tendinopathy [14,15,35].
Different injection treatments for patellar tendinopathy
have been proposed. While some studies on the effect of
dry needling, autologous blood and high volume have been
put forward as providing functional improvements, steroid
treatment has shown a relapse of symptoms after few
months, not to mention the deleterious effect on the tendon
histology [32]. Recent investigations have observed
slightly better outcomes after treatment with platelet-rich
plasma injections in association with an eccentric training
programme than an eccentric training programme alone in
short-term studies [7,30,32]. Some authors had initially
reported pain relief after sclerosing injections of polidoc-
anol [10], but recent studies have shown contradictory
results [33]. Hoksrud et al. reported their results with US-
guided sclerosis of neovessels in 29 patients with
44 months of follow-up [12] and in 101 patients with
24 months of follow-up [13]. The patients needed several
injections over 8 months of treatment, and only a moderate
improvement in knee function was observed. One-third of
their patients obtained a VISA-P score \50 points, and
only few patients were completely cured. Conversely, in
the present investigation with short- and long-term reported
outcomes, even the patients with lowest VISA-P score
(\50 points) at baseline significantly improved to around
80 points at 3 months and to around 90 points at 10 years.
These final outcomes were comparable with those obtained
by the patients with better VISA-P scores before treatment.
This is of considerable relevance because the professional
sports patients included in this series started from lower
VISA-P values and they still obtained excellent scores.
Overall, 80 % (n=32) of the treated patients returned to
the same level of sports activity at 3 months, and the
remaining eight patients only decreased a single level in
the Tegner score.
Regarding surgical treatment of patellar tendinopathy,
some open [5,21] and arthroscopic [5,20,27] techniques
have also been recommended when conservative treatment
fails. However, surgery usually provides unpredictable and
inconsistent results [4,15], which is often no more effective
than an isolated eccentric exercise programme [2], and it
does not allow the athletes to resume their previous sports at
the same level, at least within the first year of treatment [19].
The main strengths of the current study are that, as far as
we know, it is the first investigation reporting on any
treatment modality for patellar tendinopathy over the
course of 10 years. Few patients were lost during this long
follow-up period. In addition, it is also the first study
reporting on the clinical outcome using the EPI
Ò
technique
in the treatment of tendinopathy at long term follow-up.
The promising results obtained with the EPI
Ò
procedure
showed excellent functional results assessed with the
VISA-P score as well as with the Blazina’s classification in
around 80 % of the patients at 3 months and over 90 % at
10 years. It also allowed a full recovery to the previous
activity level in most patients. This outcome’s improve-
ment with the use of EPI
Ò
in the treatment of patellar
tendinopathy was achieved after a short period of time
(mean 7.5 weeks) and with a few number of treatment
sessions (mean 4.1 EPI
Ò
treatments).
Besides the low sample size, one of the most relevant
limitations of the current study is the lack of a control
group. Comparison with a placebo-treated group of
patients would have made for much stronger conclusions.
However, most of our patients were professional or semi-
professional athletes referred by other physicians after
failure of conservative therapy. It seems highly unlikely
that this sort of patients would be willing to accept pla-
cebo treatment for a long enough period. Another weak-
ness might be that the combination of treatment with
eccentric exercises might have positively affected the
results attributed to the EPI
Ò
technique. Although this
could more logically affect the results during the first
months of follow-up, it does not seem that it should have
had any influence in the long-term results. Regardless of
the aforementioned limitations, this study provides the
first analysis of the EPI
Ò
technique on the treatment of
patellar tendinopathy, with promising results after a long
follow-up period.
The clinical relevance of the reported results was that
EPI
Ò
technique brought about a major improvement in pain
and function in comparison with the so far known techniques
and offers a good treatment option in patellar tendinopathy.
Conclusion
Treatment with the US-guided EPI
Ò
technique and eccentric
exercises in patellar tendinopathy resulted in a great
improvement in knee function and a rapid return to the pre-
vious level of activity after few sessions. The procedure has
proved to be safe with no recurrences on a long-term basis.
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