DIAGNOSING, MANAGING, AND RESOLVING LAMENESS IN HORSES Evidence in Humans and Laboratory Animals
PEMF is approved by the FDA for treatment in humans with long-bone fracture nonunions and as an adjunct treatment following lumbar/cervical spine fusion surgery.73 PEMF has been shown to accelerate fracture healing in both skeletally mature normal rats and in rats with induced osteoporosis.74 PEMF significantly improved the success rate in people with delayed-union long-bone fractures with 77.4% of the PEMF treated fractures healing com- pared to 48.1% in the sham group at 4 months.75 PEMF has shown to increase bone volume fraction, trabecular thickness, trabecular number, and sup- press trabecular separation in a rat model of in- duced knee osteoarthritis. In this same study, PEMF was shown to promote Wnt gene expression in the subchondral bone. Activation of Wnt pro- motes osteoblast and osteocyte activity while indi- rectly suppressing bone resorption and osteoclast differentiation.76 In a rat model of rotator cuff tearing and repair, PEMF improved early tendon healing and bone quality.73 PEMF has also been shown to reduce pain in patients with low back pain77,78; however, caution must be taken in inter- preting these findings, as in some studies patients were not blinded to treatment or no control group was present.79,80 One study showed PEMF was not effective in reducing pain, stiffness, or improving function in women with fibromyalgia.81 However, more information on device settings for specific con- ditions is needed. One human study showed that a small change in the dose of PEMF energy applied had a significant effect on patient outcome.77
Evidence in Horses
Limited equine studies have been performed. One study from 1987 looked at the effect of PEMF for incorporation of cancellous bone grafts in ponies and found a small but statistically significant positive effect.71 Amore recent canine study showed signif- icantly faster recovery of load bearing, significantly increased new-bone formation, and higher mechan- ical strength of healing in dogs treated with PEMF following mid-diaphyseal tibial osteotomy.82 An equine study assessing tendon healing conducted in 1985 evaluated use of PEMF in surgically created defects in the SDFT. This study showed no signif- icant differences in PEMF vs control limbs for ten- don enlargement or peritendinous fibrous reaction. Interestingly, the PEMF-treated tendons showed delayed transformation of collagen from immature to mature fibers, increased vascularity, and more poorly organized and differentiated cells compared to controls. This study suggests that PEMF may actually delay tendon healing.83 However, signifi- cantly more equine research is needed to determine the efficacy of PEMF for a variety of conditions. Given the wide variability in available device pa- rameters,72 specific information regarding device settings is necessary.
286 2019 Vol. 65 AAEP PROCEEDINGS
Equine Regulations FEI
Nonrestricted supportive therapy: can be carried out by person(s) responsible for the horse and/or supportive personnel.26
USEF
No specific regulations in place. Recommended to contact USEF prior to use.27
AQHA No specific regulations in place. Recommended to contact AQHA prior to use.28
Take Home
PEMF has been shown to be effective to improve and augment bone healing. However, PEMF should be used with caution for tendon healing until further research can be performed.
8. Underwater Treadmill
Background and Mechanism of Action Underwater treadmill (UWT) training has been uti- lized in humans and horses for rehabilitation of acute and chronic injuries.84–86 UWT training is used because of effects from multiple water charac- teristics, including buoyancy, hydrostatic pressure, viscosity, drag force, and temperature.84,87 The ef- fect of buoyancy decreases the vertical ground reac- tion force,88 and allows partial weight bearing, which alleviates stress and pain on the lower- extremity joints. It also allows patients to train to improve gait when they may be deficient in muscle strength, postural control, and motor coordination.84 Hydrostatic pressure and water viscosity provide postural support to patients with impaired balance or motor control,84,89 while the drag force (resis- tance) of the water allows functional strength train- ing.90 Underwater resistance has been shown to be 12 times greater than overground resistance.91 Water temperature can be utilized to provide one of two effects—warm water can help improve the level of comfort during training,92 while use of cold water provides cryotherapy effects, including reduced pain and swelling.87 Decreased pain has also been sug- gested to occur due to stimulation of sensory recep- tors by the water.93
Evidence in Humans
UWT training has been shown to reduce body weight by 50% with the water level at the waist, 70% to 75% with the water level at the chest, and 90% with the water level at the neck.94 The effect of water depth has also been shown to affect stride length, stride cadence, and range of motion. In- creased stride length and decreased stride cadence was seen with water at the level of the neck com- pared to water at the level of the waist and chest. An increase in ankle range of motion and a decrease
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