Front Matter

146 Canine Sports Medicine and Rehabilitation

Therapeutic effects on tissue flexibility
and joint ROM

TUS is often used to provide heating to deeper
muscle (Levine et al., 2001) (Figure 7.10), ligament
(Leung et al., 2006), or tendon (Montgomery et al.,
2013). When providing thermal effects, TUS can
improve muscle flexibility (Knight et al., 2001;
Nakano et al., 2012) and increase collagen extensi­
bility (Lehmann et al., 1970; Draper et al., 1993).
This can be used to improve ROM through relax­
ation of muscle tissue (Morishita et al., 2014b) or
noncontractile tissues such as periarticular tissue
(Morrisette et al., 2004) prior to joint mobilization
(Draper, 2010).
Thermal effects may also reduce develop­
ment of muscle contracture during joint
immobilization as evidenced by continued
longitudinal orientation of collagen fibrils
and better joint ROM post‐immobilization as
compared to subjects that did not receive TUS
(Okita et al., 2009). This leads to a better func­
tional outcome following injuries that require
immobilization.
The nonthermal effects of TUS also promote
increased joint ROM. Yildiz and colleagues
investigated the effects of both pulsed and con­
tinuous TUS as compared to a control group in
human subjects with knee osteoarthritis. All
three groups were also instructed in a HEP.
Both TUS groups were found to achieve signifi­
cantly better knee ROM measurements by the

conclusion of the study, and these gains were

maintained at the 2‐month follow‐up (Yildiz

et al., 2015), suggesting that ROM benefits can

still be imparted when other patient character­

istics make nonthermal TUS the more appropri­

ate choice.

Therapeutic effects on muscle strength

As with superficial heat, TUS has not been

shown to have a direct effect on increasing

muscle strength. However, a 2015 study by

Norte and colleagues did find that treatment

with nonthermal TUS improved muscular

activity in patients with persistent quadriceps

dysfunction associated with intra‐articular

knee injuries (Norte et al., 2015). Additionally,

Matsumoto and colleagues showed that pulsed

TUS helps to inhibit the development of dis­

use muscle atrophy during joint immobiliza­

tion through stimulation of satellite cells

(Matsumoto et al., 2014).

Considerations for clinical application

When using TUS on canine patients, it should

be recalled that energy absorption is greatest in

tissues with high protein content. Hair is made

of the protein keratin. For this reason, the hair

coat can significantly reduce the delivery of

–3 036912 15 18 21 24 27

43

42

41

40

39

38

37

Time (minutes)

End

ultrasound

1cm

2cm

3cm

Begin ultrasound

Tissue temperature (°C)

Figure 7.10 Rate of temperature change at various tissue depths during and after 3.3 MHz therapeutic ultrasound (TUS)
of the caudal thigh muscle of the dog. Source: Adapted from Levine et al., 2001.