Page 975 - Adams and Stashak's Lameness in Horses, 7th Edition

Principles of Therapy for Lameness 941

injury to the recurrent laryngeal nerve and cricoaryte- not effective in reducing pain, stiffness, or improving
136
noid muscle. Horses that received electrical stimulation function in women with fibromyalgia. However, more
VetBooks.ir had an increased type I:II fiber proportion than con- needed. One human study showed that a small change
information on device settings for specific conditions is
showed improved muscle strength and geometry and
trols. NMES is typically conducted 3–5 times a week,
in the dose of PEMF energy applied had a significant
23
inducing 8–15 contractions within a treatment session. effect on patient outcome. 187
The electrodes are placed in a bipolar fashion with the
muscle at resting length or slightly lengthened at the Evidence in Horses
time of electrode placement. The rest cycle should be
5–6 times as long as the contraction, typically in a 1:6 Limited equine studies have been performed. One study
ratio. The hair coat may need to be clipped depending from 1987 looked at the effect of PEMF for incorporation
on length and should be cleaned of dirt and debris with of cancellous bone grafts in ponies and found a small but
water and coupling gel applied. statistically significant positive effect. A more recent
109
canine study showed significantly faster recovery of load
bearing, significantly increased new‐bone formation, and
Pulsed Electromagnetic Field Therapy higher mechanical strength of healing in dogs treated with
91
Mechanism of Action PEMF following mid‐diaphyseal tibial osteotomy. An
equine study assessing tendon healing conducted in 1985
Pulsed electromagnetic field (PEMF) therapy is cre- evaluated use of PEMF in surgically created defects in the
ated when an electrical current is driven through a coiled SDFT. This study showed no significant differences in
wire that generates a magnetic field. This magnetic field PEMF vs control limbs for tendon enlargement or periten-
creates small currents inside the tissue. PEMF utilizes a dinous fibrous reaction. Interestingly, the PEMF‐treated
low‐frequency and short‐phase duration, which results tendons showed delayed transformation of collagen from
in a current generated within the tissues without heat immature to mature fibers, increased vascularity, and
production. 83,166 PEMF is most commonly used to aide more poorly organized and differentiated cells compared
in bone healing. When bone deforms during weight‐ with controls. This study suggests that PEMF may actually
bearing, it becomes electrically polarized and generates delay tendon healing. However, significantly more
208
a very low electrical current. This explains Wolff’s law of equine research is needed to determine the efficacy of
functional adaptation within bone, in which this electri- PEMF for a variety of conditions. Given the wide variabil-
cal signal regulates the osseous elements and maintains ity in available device parameters, specific information
57
bone mass. PEMF also generates a weak electric cur- regarding device settings is necessary.
174
rent in the tissue similar to those generated by bone in
response to mechanical deformation, thus stimulating
osteogenesis. 109,220 PEMF has also been shown to help Underwater Treadmill
reduce pain and inflammation, mainly through its stim-
ulation of nitric oxide, which results in vasodilation and Mechanism of Action
enhanced circulation. 180 Underwater treadmill (UWT) training has been uti-
lized in humans and horses for rehabilitation of acute
and chronic injuries. 99,106,107 Underwater treadmill train-
Evidence in Humans and Laboratory Animals
ing is used because of effects from multiple water charac-
PEMF is approved by the FDA for treatment in teristics, including buoyancy, hydrostatic pressure,
humans with long‐bone fracture nonunions and as an viscosity, drag force, and temperature. 99,106 The effect of
adjunct treatment following lumbar/cervical spine buoyancy decreases the vertical ground reaction force
137
198
fusion surgery. PEMF has been shown to accelerate and allows partial weight‐bearing, which alleviates stress
fracture healing in both skeletally mature normal rats and pain on the lower extremity joints. It also allows
9
and in rats with induced osteoporosis. PEMF signifi- patients to train to improve gait when they may be defi-
cantly improved the success rate in people with delayed cient in muscle strength, postural control, and motor
union long‐bone fractures with 77.4% of the PEMF‐ coordination. Hydrostatic pressure and water viscosity
99
treated fractures healing compared with 48.1% in the provide postural support to patients with impaired bal-
180
sham group at 4 months. PEMF has shown to increase ance or motor control 99,178 while the drag force (resist-
bone volume fraction, trabecular thickness, trabecular ance) of the water allows functional strength training. 130
number, and suppress trabecular separation in a rat Underwater resistance has been shown to be 12 times
model of induced knee osteoarthritis. In this same study, greater than over ground resistance. Water tempera-
117
PEMF was shown to promote WNT gene expression in ture can be utilized to provide one of two effects – warm
the subchondral bone. Activation of WNT promotes water can help improve the level of comfort during
osteoblast and osteocyte activity while indirectly sup- training, while use of cold water provides cryotherapy
67
pressing bone resorption and osteoclast differentia- effects, including reduced pain and swelling. Decreased
105
217
tion. In a rat model of rotator cuff tearing and repair, pain has also been suggested to occur due to stimulation
PEMF improved early tendon healing and bone qual- of sensory receptors by the water. 129
198
ity. PEMF has also been shown to reduce pain in
patients with low back pain; 49,187 however caution must
be taken in interpreting these findings, as in some stud- Evidence in Humans
ies patients were not blinded to treatment or no control Underwater treadmill training has been shown to
group was present. 88,173 One study showed PEMF was reduce body weight by 50% with the water level that is