Page 139 - JSOM Spring 2020

as shown in Table 3. Although these are promising prelim- Shock Wave Therapy
inary results, further studies of hyaluronic acid injections Shock wave therapy (SWT) uses either pressurized air or elec-
are needed that include sham injections to rule out placebo tromagnetic pluses to deliver a series of rapid and short shock
effects. waves directly over the Achilles tendon to treat AT. In clinical
application the shock wave can be focused, defocused, or ra-
Platelet-Rich Plasma Injections. Platelet-rich plasma injections dial. As the names imply, focused shock waves concentrate the
have shown promise for treating a number of musculoskeletal energy to a specific point in the tissue while defocused shock
disorders. The process for obtaining the plasma involves cen- waves distribute the energy over a larger surface area. Radial
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trifugation of a patient’s blood to obtain a high concentration SWT produces maximal energy at the source (transducer head)
of platelets, cytokines, and other substances involved in tissue and the energy gradually dissipates as it enters the tissue. Ra-
healing. This preparation is then injected into the affected tis- dial shock waves have a more superficial effect while focused
sue. A recent systematic review of 4 randomized controlled and defocused types can deliver the energy deeper into the tis-
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trials involving platelet-rich injections into tendons of patients sue. 109,110 Different amounts of energy (measured as mJ/mm )
2
with AT showed no difference in either pain, symptoms (mea- can be applied to the tissue with the SWT device.
sured with the VISA-A scale), or ultrasound evaluations at any
follow-up period (3 months to 1 year). However, all of the The mechanism by which SWT works is not fully understood,
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studies in the systematic review involved a single platelet-rich but some aspects of the process have been researched. In stud-
injection. A study not included in the systematic review pro- ies of isolated tenocytes from healthy human tendons, SWT
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vided patients 4 platelet-rich plasma injections, each spaced 2 promoted the growth of tenocytes and significantly increased
weeks apart. At follow-up periods of 6, 12, and 24 weeks in- type I collagen. However, in isolated tenocytes from rup-
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vestigators found greater decreases in pain and improvements tured Achilles tendons SWT resulted in a decrease of type I
in function in the platelet-rich injection group when compared collagen, although the migration and proliferation of teno-
to a group receiving sham injections. Both groups included ec- cytes increased relative to tenocytes from healthy Achilles ten-
centric exercise (Alfredson protocol) as part of their treatment. dons. Ultrasound studies in patients with AT and studies
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In summary, more research is needed before platelet-rich injec- in rabbit tendons suggest that SWT induces tendon neovas-
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tions can be recommended for AT treatment, but multiple in- cularization. In animal models of AT, SWT reduced adhesions
jection protocols may be more promising that a single injection. in the tendon, resulted in better organization of collagen,
TABLE 3 Summary of the Effects of Hyaluronic Acid Injection on Pain, Function, and Tendon Thickness in Treatment of Achilles
Tendinopathy
P Value
Follow-Up (Compared P Value
Initial Sample Size (N), Experimental Groups Period With (Comparing
Study Conditions, Patient Inclusion Criteria Measure (If Any) (weeks) Values Baseline) Treatments)
Kumai et al., N = 15 HAI only 0 (baseline) 4.6 ± 2.0
2014 106 Patients with pain around the Achilles tendon VAS
on jumping, walking, or running with pain 1 2.8 ± 2.1 <.01
around retrocalcaneal bursa
Fogli et al., N = 34 HAI only 0 (baseline) 7.9 ± 1.4
2017 104 Patients with symptoms including tendon 1 5.0 ± 1.5 a <.01
swelling, pain on palpation, limited range of VAS 2 3.9 ± 2.1 <.01
motion for ≥ 6 weeks and pain >5 on VAS
(insertional AT) 8 2.0 ± 2.1 <.01
Tendon 0 9.4 ± 2.4
Thickness 2 8.4 ± 2.6 NR
(mm) 8 8.3 ± 2.3 NR
Lynen et al., 1. N = 29 HAI HAI 0 (baseline) 6.3 NR
2017 105 2. N = 30 SWT SWT 6.9
Patients with painful midportion AT for ≥6 HAI 4 1.8 <.05
weeks and VAS >4 SWT 3.3
VAS
HAI 0.6
SWT 12 2.8 <.05
HAI 0.3
SWT 24 2.2 <.05
HAI 0 (baseline) 34 NR
SWT 32
HAI 4 64 <.05
SWT 51
VISA-A
HAI 12 73 <.05
SWT 48
HAI 75
SWT 24 52 <.05
HAI, hyaluronic acid injection, SWT, shock wave therapy; VAS, visual analog scale (1-10 with 10 worst pain); NR, not reported; AT, Achilles
tendinopathy; VISA-A (higher scores indicate less pain and greater function).
a Value estimated from Figure 3.

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