Page 140 - JSOM Spring 2020

increased capillarization of the tissue, increased thickness of More research is needed on low-level laser therapy before this
the epitenon, and increased force required to rupture the ten- can be recommended for AT treatment.
don. It also promoted healing by increasing the expression
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of growth factors (specifically transforming growth factor β1 Prevention
and insulin-like growth factor 1). 116
There are very few studies that have examined strategies for
Table 4 shows the results of studies that have examined the ef- prevention of AT and these studies varied widely in the types of
fectiveness of SWT for reducing pain and improving function. interventions examined. Table 6 shows randomized controlled
Studies are separated into those examining patients with mid- studies and historical cohort studies that investigated the effec-
portion AT, insertional AT, and those with both types. Note tiveness of these interventions. In most cases, 137–143 it was nec-
that studies used different types of SWT (focused vs radial) and essary to do a secondary analysis of the data since the authors
had different follow-up periods. Most 117–125 but not all 126–128 did not provide a separate analysis of the AT data. When this
studies included patients who had not responded to conven- was necessary, a chi square analysis was performed comparing
tional treatment. In general, both focused and radial SWT the numbers of injured and noninjured participants in the inter-
were effective in reducing pain and improving function in vention and control groups using the Open Source Epidemio-
both midpoint and insertional AT patients. 117–128 Two separate logic Calculator. Note that the large majority of these studies
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studies by the same author 119,121 suggested that a single session (Milgrom, 1992; Pope, 1998; Amako, 2003; Larsen, 2010;
of focused SWT was more effective than conventional treat- House, 2013; Bonanno, 2018) involved military conscripts or
ments for both midportion and insertional AT, but the type recruits. Table 6 shows that the AT case definitions and how
of conventional treatments were highly variable and not well the data were obtained varied considerably in these studies and
defined. Two studies 125,128 found that SWT was about equally the number of AT cases were very low in many. 138–141,143
effective in reducing pain and improving function for both in-
sertional and midpoint AT. When SWT was compared to ec- The three studies 138–140 that examined stretching found that
centric exercise (Alfredson protocol), both were about equally it was not effective, but the number of AT cases was ex-
effective in improving pain and function for midportion AT, tremely small in all three studies. Even if the data from the
118
but less so for insertional AT. A study in which patients three stretching studies 138–140 were combined in a meta-analysis
122
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initially started therapy with the Alfredson eccentric exercise (random model), there were no differences between groups in
protocol and had SWT beginning 4 weeks later (3 treatments) AT risk (summary risk ratio (stretching/no stretching) = 1.43,
found that this procedure was more effective for reducing pain 95% CI = 0.36-5.57). The study that compared a high top,
137
and improving function than eccentric exercise alone. shock absorbent basketball shoe to a combat boot during Is-
raeli conscript basic training found little difference between
Other reviews 129,130 on the effectiveness of SWT have generally the two groups in terms of AT prevention. Two studies 141,143
concurred with the finding reported here. One review had examined the effectiveness of custom orthotics in boots during
129
specific recommendations for the SWT protocol to be used basic training and found no difference in AT incidence between
for AT. For midportion AT they recommended using radial the orthotic group and their respective controls, although
SWT to “deliver 2000 impulses at 3 bar (energy flux density both studies 141,143 had few AT cases. A study that examined
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of 0.1mJ/mm ) at 8 Hz for 3 sessions at weekly intervals.” For whether or not asymptomatic runners with more pain over
2
insertional AT they recommended using radial SWT to “de- the Achilles tendon (pressure applied directly to the tendon
liver 2000 impulses at 2.5 bar (energy flux density of 0.12mJ/ with an algometer) subsequently developed AT over 500 km
mm ) at 8 Hz for 3 sessions at weekly intervals.” In summary, of running found no difference between runners with high
2
the data support the use of SWT for patients who have not pain sensitivity versus those with low pain sensitivity. Another
responded well to conventional treatments. study with a large number of AT cases compared a slightly
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molded shock absorbing insole to an insole not designed for
Low-Level Laser Therapy shock absorption and found a significantly lower incidence of
Laser therapy involves the use of low power (<0.5 W) laser AT with the former. Finally, a study of elite female soccer
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sources at wavelengths (630 to 900 nm) that can penetrate players found that a complex balance training program ap-
soft tissues, but do not cause temperature changes within the plied over several sports seasons reduced AT injury rates. In
tissues. Studies since the mid-1980s have suggested that this summary, it appears that the use of shock absorbing insoles
modality can be effective in the treatment of various tendinopa- and balance training are promising interventions to prevent
thies if appropriate dosages are applied to the tissue. Animal AT, but given that there is only one study for each intervention
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studies found that after Achilles tendon injury, low-level laser further research is needed.
treatment resulted in tenocyte proliferation and migration, in-
creases in type I and type III collagen, and an increase in in- Prediction/Screening for AT
terleukin-10, an important anti-inflammatory cytokine. 132–134
However, the two human trials that have been conducted are Ultrasonography has been used to diagnosis AT, but could
conflicting as shown in Table 5. A study with only 10 pa- this technique could be useful for predicting the develop-
135
tients in each group found that both laser treatment and a ment of symptomatic AT? This question was examined in a
placebo had similar effects on self-reported Achilles tendon systematic review that included nine studies with athletes
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pain and VISA-A scores. However another study involving as participants. The outcome measure was tendon abnormali-
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20 patients in each group showed that laser therapy resulted ties, defined as any deviation from a normal tendon structure
in greater reductions in pain, morning stiffness, and tenderness seen on ultrasonography (e.g., increased tendon thickness, in-
on palpation compared to a placebo (i.e., laser probe on treat- creased vascularity, hypoechogenicity). Meta-analysis could
ment area, but not turned on). Both studies included eccentric be performed on five investigations that provided data on AT
exercise (Alfredson protocol) as part of the treatment plan. cases that became symptomatic after the ultrasonography was

134 | JSOM Volume 20, Edition 1 / Spring 2020