Rehabilitation Modalities for Pain Management and Healing
Physical rehabilitation is an emerging area of veterinary medicine. Multiple training programs offer certification in canine rehabilitation, board certification with the American College of Veterinary Sports Medicine and Rehabilitation, and credentialing with the Academy of Physical Rehabilitation Veterinary Technicians. Rehabilitation modalities can be particularly useful as part of a multimodal pain management program. Rehabilitative methods can improve patient comfort and quality of life, especially in cases where pharmaceutical pain relievers are contraindicated. This article reviews some of the more common modalities that can be used to help reduce pain, enhance tissue healing, and improve patient function, as well as highlights associated evidence of efficacy (TABLE 1).
Which modality to choose depends largely on specific patient needs and the condition being treated. Although modalities can sometimes be used simultaneously, the synergistic or countereffects they may have on each other remain unknown. For this reason, you should consider the main goal of therapy and choose the most appropriate modality for addressing that goal.
Perhaps the most commonly used rehabilitative modality is laser therapy, which stands for light amplification by stimulated emission of radiation (FIGURE 1). This modality has more recently been called photobiomodulation, primarily because therapeutic lasers modulate biological cellular activity as opposed to other nontherapeutic lasers (e.g., grocery store scanners or laser pointers) that do not have a biological effect.
One proposed mode of action for therapeutic laser is stimulation of the respiratory chain in the mitochondria. The respiratory chain is a complex of genes that provide instructions for proteins involved in oxidative phosphorylation. As light enters the cell, it is absorbed by cytochrome c oxidase (the next-to-last step in the mitochondrial respiratory chain process) leading to increased production of adenosine triphosphate. Cells also release low levels of ROS (reactive oxygen species), resulting in endogenous anti-oxidant production by the cell and release of nitrous oxide, which leads to vasodilation and increased perfusion.
Lasers are classified according to risk for eye injury. The higher the class of laser, the greater the risk for eye injury and thermal damage to eyes and/or other tissue. Class 4 lasers are defined as those with power output of 500 mW and above. In general, therapeutic lasers with potential for photobiomodulation are Class 3 and above and require protective eyewear. Lower-class lasers can have photobiomodulation potential when tissues are exposed for a longer time at specific wavelengths. In general, lower wavelengths are more effective for superficial tissues (~600 nm) and higher wavelengths, for deeper tissues (up to 3 to 5 cm, or 800 to 900 nm).
Several recently published studies evaluated the efficacy of using photobiomodulation in veterinary medicine.1-10 The results can be difficult to interpret because of the large number of different products on the market and variations in protocols and outcome measures. Thus, we should be cautious when making conclusions. Some authors question whether photobiomodulation can help improve recovery after hemilaminectomy in dogs. Draper et al. found that dogs receiving a low-level Class 3B laser (810-nm wavelength for 1 minute daily for 5 days) regained the ability to ambulate significantly faster than untreated dogs (3.5 vs 14 days).1 In contrast, using the same laser and protocol, Bennaim et al. found no difference in outcome between laser and placebo groups.2 In another prospective study evaluating wound healing, Kurach et al. found no apparent beneficial effects for dogs with experimentally induced incisions and subsequent exposure to a Class 2 laser (635-nm wavelength laser for 5 minutes for a total dose of approximately 1 J/cm2).3 When Kennedy et al. evaluated this same laser in a prospective study, they found no beneficial effects on pain, radiographic healing, or pelvic limb function in dogs who received this Class 2 laser before and 10 times after tibial plateau-leveling osteotomy (TPLO) for the first 96 hours at 2.5 J/cm2 and then weekly at home for 4 weeks (at 1.5 J/cm2).4 However, those studies may have failed to demonstrate lack of efficacy because they used a lower class of laser. Usually, rehabilitation practitioners use Class 3B lasers and above. A small study demonstrated improved scores in incisional scars in 4 dogs who received postoperative photobiomodulation daily for 7 days at 8 J/cm2 with a Class 3B laser compared with 5 dogs who did not receive photobiomodulation.10
Lasers are classified according to risk for eye injury. The higher the class of laser, the greater the risk for eye injury and thermal damage to eyes and/or other tissue.
Another study that evaluated the effects of laser on dogs after TPLO found improved pelvic limb function (determined by measuring peak vertical force with a pressure mat system).5 Those dogs received a single Class 4 laser dose with dual 800- and 970-nm wavelengths, at 6 W for a unified dose of 3.5 J/cm2 over a 100-cm2 area.5 In another recent prospective blinded study, dogs with naturally occurring elbow osteoarthritis demonstrated reduced lameness, pain scores, and nonsteroidal anti-inflammatory drug dosages compared with placebo-treated dogs.6 The treated dogs received photobiomodulation therapy with a Class 4 laser twice weekly for 3 weeks and then weekly for 3 weeks at a dose of 10 to 20 J/cm2 per joint.6
As previously stated, use of wide-ranging doses and various laser devices make it difficult to base conclusions on these limited data. Larger prospective, randomized, controlled clinical trials are needed before any conclusions about the therapeutic benefits of laser use in companion animals can be reached.
In human medicine, data are also not conclusive. A systematic review of the treatment of plantar fasciitis in people showed reduced pain and improved function; however, laser doses varied widely among studies, making it difficult to determine best treatment parameters.7 Another recent systematic review and meta-analysis of photobiomodulation effects on bone healing in humans showed improvement in pain and function; however, the level of evidence is considered low to very low, and no effect on radiographic healing of the fracture line was found.8 Similarly, results of a systematic review of low-level laser on pressure ulcers in humans were conflicting and not conclusive.9
PULSED ELECTROMAGNETIC FIELD THERAPY
Another rehabilitation modality that has recently gained popularity and become widely available to rehabilitation and general practitioners is pulsed electromagnetic field (PEMF) therapy (FIGURE 1). This technology has been available for over a century; however, it became more popularized in the 1980s when the Food and Drug Administration approved low-powered PEMF devices as bone growth stimulators. Since then, the technology has been further developed and targeted. There are many devices on the market, including PEMF beds and devices that provide more targeted therapy, such as a loop device. Of note, the particular signal of the device affects its therapeutic potential. Variations exist in pulse width, pulse frequency, size and geometry of the antenna, and duration of the signal. The targeted shortwave forms (27 mHz, 2-ms pulse width, 2-Hz pulse frequency) are thought to be more effective. Practitioners are advised to ask PEMF manufacturers what specific signal is used by their product and what evidence they have to support their dosage recommendations. In general, acute conditions should be treated 3 to 4 times daily for 5 to 10 days until pain resolves. Chronic conditions can be treated once or twice daily or even less frequently, depending on response. The postulated mode of action for the signal emitted by the loop device is upregulation of the voltage-dependent binding of calcium to calmodulin. This binding enhances release of constitutive nitrous oxide synthase, leading to vasodilation and an anti-inflammatory cascade.
The most notable benefits of PEMF include pain relief, increased wound healing, and reduced soft tissue pain and edema (TABLE 1). Two recent randomized and controlled clinical trials demonstrated benefits of PEMF use on recovery of dogs after hemilaminectomy.11,12 In particular, Alvarez et al. demonstrated reduced client administration of opioid medications during the initial 7-day postoperative period for dogs who received PEMF therapy compared with those who received placebo.11 In addition, 6-week postoperative wound scores were better for treated than control dogs.11
With regard to potential side effects, PEMF is perhaps one of the most benign of the rehabilitation modalities. However, its use is contraindicated for patients with pacemakers or arrhythmias and those with active hemorrhage.
EXTRACORPOREAL SHOCKWAVE THERAPY
Shockwave therapy was first introduced as a method for breaking up urinary calculi (lithotripsy). Since then, the technology has advanced and is widely used in human and veterinary medicine for treatment of nonunion or delayed union fractures, wound healing, tendinopathies, arthritis, and other conditions. Among rehabilitation modalities in the veterinary field, the level of evidence for efficacy is perhaps highest for extracorporeal shockwave (ECSW) therapy (TABLE 1). The mode of action is emission of acoustic waves at high velocity and pressure. A large amount of energy is deposited in the tissues, creating cavitation bubbles that subsequently collapse and lead to increased cellular permeability and expression of cytokines and growth factors. Because the pressure waves of ECSW are emitted at lower frequency than those of therapeutic ultrasonography, they cause no thermal effect. The analgesic effects most likely result from nociceptor stimulation and endorphin release.
The most notable benefits of PEMF include pain relief, increased wound healing, and reduced soft tissue pain and edema.
A variety of ECSW devices, with varying effectiveness, are available. In particular, devices can vary by depth of penetration and focal area. Therefore, devices should be chosen according to the condition being treated and available evidence to support that use. Focal superficial signal devices may be more effective for treating myofascial trigger points, whereas electrohydraulic devices with higher energy and deeper penetration may be more appropriate for treating nonunion fractures, osteoarthritis, or other deeper tissue disorders. Several prospective studies that used higher energy and deeper signal devices demonstrated efficacy for treating patellar desmitis after TPLO,13 acceleration of bone healing,14 and osteoarthritis15; retrospective studies demonstrated efficacy for treating shoulder tendinopathies (FIGURE 2).16,17 Contraindications include use on patients with immune-mediated joint disease, septic arthritis, neoplasia, diskospondylitis, unstable fractures, and neurologic deficits.
- Rehabilitation modalities are used to help reduce pain and enhance tissue healing.
- Choice of rehabilitation modality should be based on the patient’s needs, the condition being treated, and level of evidence.
- Laser: Prospective clinical trials in veterinary medicine are reported for hemilaminectomy, TPLO, and elbow osteoarthritis. Results are not conclusive enough to use for clinical decision making.
- PEMF: Most notable published veterinary benefits include pain relief, increased wound healing, and improved recovery after hemilaminectomy.
- ECSW: Sufficient evidence in dogs exists to warrant use for nonunion or delayed union fractures, tendinopathies, and arthritis.
- Overall, rehabilitation modalities can be part of a multimodal pain management program and can improve patient comfort and function in a noninvasive manner.
1. Draper WE, Schubert TA, Clemmons RM, et al. Low-level laser therapy reduces time to ambulation in dogs after hemilaminectomy: a preliminary study. J Small Anim Pract 2012;53(8):465-469.
2. Bennaim M, Porato M, Jarleton A, et al. Preliminary evaluation of the effects of photobiomodulation therapy and physical rehabilitation on early postoperative recovery of dogs undergoing hemilaminectomy for treatment of thoracolumbar intervertebral disk disease. Am J Vet Res 2017;78(2):195-206.
3. Kurach LM, Stanley BJ, Gazzola KM, et al. The effect of low-level laser therapy on the healing of open wounds in dogs. Vet Surg 2015;44(8):988-996.
4. Kennedy KC, Martinez SA, Martinez SE, et al. Effects of low-level laser therapy on bone healing and signs of pain in dogs following tibial plateau leveling osteotomy. Am J Vet Res 2018;79(8):893-904.
5. Rogatko CP, Baltzer WI, Tennant R. Preoperative low level laser therapy in dogs undergoing tibial plateau leveling ostetomy: a blinded, prospective, randomized trial. Vet Comp Orthop Traumatol 2017;30(1):46-53.
6. Looney AL, Huntingford JL, Blaeser LL, et al. A randomized placebo-controlled trial investigating the effects of photobiomodulation therapy (PBMT) on canine elbow osteoarthritis. Can Vet J 2018;59(9):959-966.
7. Dos Santos SA, Sampaio LM, Caires JR, et al. Parameters and effects of photobiomodulation in plantar fasciitis: a meta-analysis and systematic review. Photobiomodul Photomed Laser Surg 2019;37(6):327-335.
8. Neto FCJ, Martimbianco ALC, de Andrade RP, et al. Effects of photobiomodulation in the treatment of fractures: a systematic review and meta-analysis of randomized clinical trials. Lasers Med Sci 2019 April 13. doi: 10.1007/s10103-019-02779-4 [Epub ahead of print]. Accessed June 2019.
9. Machado RS, Viana S, Sbruzzi G. Low-level laser therapy in the treatment of pressure ulcers: systematic review. Lasers Med Sci 2017;32(4):937-944.
10. Wardlaw JL, Gazzola KM, Wagoner A, et al. Laser therapy for incision healing in 9 dogs. Front Vet Sci 2019;5:349.
11. Alvarez LX, McCue J, Lam NK et al. Effect of targeted pulsed therapy on canine postoperative hemilaminectomy: a double-blind, randomized, placebo-controlled clinical trial. JAAHA 2019;55(2):83-91.
12. Zidan N, Fenn J, Griffith E, et al. The effect of electromagnetic fields on post-operative pain and locomotor recovery in dogs with acute, severe thoracolumbar intervertertebral disc extrusion: a randomized placebo-controlled, prospective clinical trial. J Neurotrauma 2018;35(15):1726-1736.
13. Gallagher A, Cross AR, Sepulveda G. The effect of shockwave therapy on patellar ligament desmitis after tibial plateau leveling osteotomy. Vet Surg 2012;41(4):482-485.
14. Kieves NR, MacKay CS, Adducci K, et al. High energy focused shock wave therapy accelerates bone healing: a blinded, prospective, randomized canine clinical trial. Vet Comp Orthop Traumatol 2015;28:425-432.
15. Souza AN, Ferreira MP, Hagen SC, et al. Radial shock wave therapy in dogs with hip osteoarthritis. Vet Comp Orthop Traumatol 2016;29(2):108-114.
16. Becker W, Kowalesky MP, McCarthy RJ, et al. Extracorporeal shockwave therapy for shoulder lameness in dogs. JAAHA 2015;51(1):15-19.
17. Leeman JJ, Shaw KK, Mison MB et al. Extracorporeal shockwave therapy and therapeutic exercise for supraspinatus and biceps tendinopathies in 29 dogs. Vet Rec 2016;179(15):385.