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Physical
Therapy in Veterinary Medicine
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Physical Therapy in Veterinary Medicine
Shock Wave Therapy can Promote Bone Healing and Reduce
Pain
Physical Therapy in Veterinary Medicine
Robert
Taylor United States
There is a lot of interest in canine physical therapy and rehabilitation
and courses are being offered at many of the major meetings. There is one
certification process in motion, which will be sanctioned by several universities,
and active canine physical therapy related research is happening. What
has triggered this interest?
There are several factors to consider:
1. Public demand.
2. Emergence of the working dog; with need to return
to previous level of activity.
3. Demonstrated efficacy in other species (man).
4. Increased sophistication in veterinary surgery.
5. Animals are living longer.
6. Adds value to veterinary services.
7. Potential source of veterinary income.
8. Rewarding to veterinary staff, owner and animal.
In the recent past, there was little attention paid to post operative
care and many animals were lost to follow-up following suture removal.
This, coupled with the notion that the animal would use the limb when it
felt “good” and the reluctance on the part of veterinarians to urge early
mobility, were factors that limited the use and concept of physical therapy.
In spite of recent advances, there are still veterinary surgeons that routinely
immobilize their post-operative cruciate patients for four to six weeks,
and this is often done with casts, braces, or splints. Early motion has been
shown to be efficacious in hastening recovery and limiting the effects of
disuse on bone, cartilage, periarticular soft tissue, ligaments, and tendons.
The goal of physical therapy and rehabilitation is to return the
affected part and the animal to full function. We first began our Physical
Therapy and Rehabilitation (PTH) program working with racing Greyhounds.
Owners and trainers were reluctant to invest the time and money to allow
us to repair their injuries unless we could insure that they would return
to the track and perform at their previous level or better. While we were
not always successful, we learned the value of early and appropriate PTH.
One current challenge is to prove that PTH is as meritorious in
the dog as it has been in man. There are many studies done in man demonstrating
the value of PTH on earlier recovery, resumption of lifestyle, return to
athleticism, and enhanced quality of life. There have been studies in animals,
notably Johnson’s work on early use of electrostimulation; Levine and Millis’
work on goniometry, range of motion and ultrasound; Steiss on ultrasound;
Adamson on photon therapy and the underwater treadmill; to mention only
a few. The recent interest will only stimulate new areas of investigation
and research.
PTH measures should be included in every post-surgical plan.
The benefits of PTH include:
1. Increased blood flow and lymphatic drainage to the
injured area.
2. Early resolution of inflammation.
3. Increased production of collagen.
4. Prevention of periarticular contractions.
5. Promotion of normal joint homeostasis.
6. Promotion of normal joint biomechanics.
7. Prevention or minimize muscle atrophy.
8. Positive psychological effects for the animal and
owner.
There are two distinct intervals in the recovery process where
PTH can be useful to facilitate full post-surgical recovery and return
to function. For every one patient recovering from a traumatic injury and/or
surgery there are ten patients who could benefit from PTH and these patients
include those with obesity, degenerative joint disease, tissue atrophy and
residual neurologic disease. For purposes of this paper, we will address
the needs of the post trauma surgery patient.
PHASE ONE
Phase 1 activities begin the day of surgery and typically involve
icing, passive range of motion, and early wound mobilization. This period
begins with the traumatic injury and or surgery and encompasses the inflammatory
phase and early wound healing that occurs in the first three to four weeks.
The goal of PTH during this time is to minimize inflammation and pain,
preserve joint range of motion, and to prevent or further minimize muscle
and soft tissue atrophy.
PHASE TWO
Phase 2 activities begin as inflammation is resolving and healing
begins to be the predominate theme in the wound. It is very important to
combine phase two activities with the temporal aspects of wound healing. By
that, we mean applying appropriate stresses to healing tissues so as to optimize
their healing but not so much that the biomechanical stability is threatened.
Ideally, the phase two activities should parallel the gradual increase in
tensile strength observed in the wound. If one is too aggressive with PTH
during this period, failure can occur; conversely, if one lags in PTH activities,
the goal of early return to function is not accomplished.
RESPONSE OF CONNECTIVE TISSUES TO DISUSE AND IMMOBILIZATION
In order to better understand the needs of PTH during recovery
it is appropriate to understand the way connective tissues respond to immobilization
and disuse.
Skeletal muscle changes from reduced weight bearing and loading:
1. Type 1 muscle fiber and muscles with a large population of type
1 fibres show perpetual atrophy. These include the extensor muscles and
the antigravity muscles.
2. The loss of muscle strength is caused by not only atrophy but
biochemical changes in the sarcoplasmic reticulum.
3. Normal dogs undergoing surgical transaction of the cranial cruciate
ligament and immediate stabilization undergo early atrophy of the affected
limb muscles, which continues for at least five weeks. The atrophy is most
significant in the quadriceps, biceps semitendinosus, and semimembraneous
muscle groups.
4. The presence of fast twitch proteins in slow twitch muscle fibres
indicating a biochemical conversion of these fibres.
Ligament changes to immobilization:
1. Stress reduction is detrimental to the mechanical, biochemical
and structural properties of collagen and ligaments. Following five weeks
of immobilization of the knee of primates, there was a 39% decrease in maximum
load to failure (Noyes).
2. Stress reduction in a rabbit femur ligament tibia model produced
a 69% decrease in load to failure (Woo et al.).
Cartilage changes associated with reduced weight bearing and
immobilization:
1. Immobilization creates degenerative changes in the articular
cartilage. There a gradual reduction in proteoglycan content of the cartilage,
thinning of cartilage, a decrease in proteoglycan production, and loss of
subchondral bone. Immobilization of a limb in extension results in increased
muscle contraction and changes similar to those seen in osteoarthritic cartilage
including osteophyte formation, fibrillation of cartilage, pitting, and
erosion of articular cartilage.
Bone changes associated with immobilization and disuse:
1. Immobilization causes decreased bone formation, increased bone
absorption and trabecular bone is more affected than cortical bone. The effects
of immobilization are most pronounced on distal bones.
2. Immobilization (stages of response):
a. Stage 1: six weeks of immobilization, quick
loss with near full recovery requiring 8–12 weeks.
b. Stage 2: 12–32 weeks of immobilization slower
loss but longer recovery.
c. Stage 3: Greater than 32 weeks of immobilization
loss maintained at 30–50% of normal.
WOUND HEALING
Those involved in PTH must be students of wound healing. For example,
it is important to know that tendons subjected to surgical repair only
have 40% of their tensile strength at four months. The reader is referred
to a standard text for a more in-depth discussion of the temporal aspects
of wound healing. It is important that the PTH activities parallel the acquisition
of wound strength during the period of immobilization and healing.
PTH Modalities
Modalities that are currently used in veterinary PTH include therapeutic
ultrasound, neuromuscular stimulation, cryotherapy, heat therapy, massage,
therapeutic exercise, aquatic therapy, and passive range of motion activity.
Each of these modalities will be discussed in the lecture portion of the
presentation.
Ultrasound
Therapeutic ultrasound is a commonly used modality in PTH and has
been shown in clinical and scientific trials to increase collagen extensibility,
enhance collagen remodelling, enhance collagen production, increase heat
in deep tissues, increase blood flow, increase range of motion, reduce pain
and muscle spasm, and accelerate wound healing. Therapeutic ultrasound is
produced by applying an electric current through a piezoelectric crystal
causing it to vibrate at its resonance frequency. These oscillations of the
crystal cause pressure waves to be emitted and these are subsequently absorbed
by the tissues. The two most commonly used US frequencies are 1.0 MHz and
3.3 MHz. The 1 MHz penetrates more deeply and is used for heating tissues
from 2–5 cm in depth. The 3.3 MHz head is used to heat tissues to a depth
of 1–2 cm. With the 3.3 MHz head maximum heat is generated at the 2 cm level.
In most cases, the amount of time tissue temperatures remain elevated is
short (within 10 minutes).
The thermal effects of US include:
1. Increased metabolic rate of tissues.
2. Increased blood and lymphatic flow.
3. Increased extensibility of collagenous tissues (tendons,
scars, muscle sheaths, joint capsules, ligaments).
4. Decreased pain and muscle spasm.
The non-thermal effects of US are:
1. Increased cell diffusion and cell membrane permeability.
2. Increased production of collagen and hydroxyproline.
3. Increased fibroblast proliferation and activity
increases GAG synthesis.
Dosage
The rate at which the US energy is delivered per unit area is expressed
in Watts/cm2. Intensities of 1–2 W/cm2 are used in areas that have a lot
of muscle (such as the thigh) and less intensity is used for other areas
(0.5–1.0 W/cm2). Continuous US is best used to heat tissues, and if available,
the pulsed delivery is used when the non-thermal effects of US are desired.
Coupling Agent
A coupling agent is needed to connect the US head with the skin
in order to maximize transfer of the US energy in top the tissues. Water
soluble gels are advisable.
Treatment time and frequency
It is important that the hair be clipped over the desired treatment
area. Steiss has shown that the presence of hair interferes with the absorption
of the US energy and it is possible to burn the skin if this is not done,
furthermore the hair absorbs the US energy and little is available to heating
deeper tissues. The time necessary to treat an area depends on the size
of the treatment area and the size of the transducer head. One can estimate
how many transducer heads fit into the treatment area and for every two
heads allow five minutes. We typically do daily or every other day treatments.
Electrical stimulation
The use of electrical stimulation to stimulate a peripheral nerve
to cause the desired effect is called neuromuscular stimulation. Electrical
stimulation is a commonly used modality in PTH and been shown efficacious
in:
1. Increasing muscle strength.
2. Improving muscle tone.
3. Increasing range of motion.
4. Pain relief.
5. Muscle re-education.
6. Reducing muscle spasms.
Current types
AC current is commonly used for muscle stimulation and reeducation
delivered in a pulsed format. Medium frequency polyphasic current is called
Russian stimulation. The device is connected to the patient via a pair
or more electrodes. They should be flexible, offer low resistance, and
may be trimmed to custom fit the part of the body where they will be used.
Treatment parameters
Amplitude is the size of the current wave form. Ramp is the time
from the beginning of the phase to increase in amplitude from the zero
current baseline to the peak amplitude. Wave form, the shape of the visual
representation of pulsed current, can be symmetrical, asymmetrical, balanced,
unbalanced, monophasic, or polyphasic. Frequency, the rate of oscillation
in cycle/second, expressed as pulses/sec. on/off time, indicates the amount
of time the stimulator is delivering current compared to the rest period
between contractions.
Current Parameters for strengthening:
Millis and Levine recommend a frequency of 25–50Hz/sec with a biphasic
wave form with pulse duration of 150–250 microseconds with a 2–4 second
ramp time.
THERAPEUTIC EXERCISE
Of all the modalities used in Canine Physical Therapy, therapeutic
exercise is often the most effective in cost and achievement. Therapeutic
exercise (TE) can be utilized in every clinic and its use and implementation
is only limited by one’s imagination. TE can be used to preserve ROM and
muscle mass and to challenge healing tissues during recovery.
An important factor to acknowledge is the need to match the specific
injury/and or surgical repair with the appropriate exercise. We know from
clinical/research data in animals and man that following cranial cruciate
loss/repair the quadriceps, biceps and semimembranosus under go significant
atrophy. When developing a TE plan for a postoperative cruciate patient,
we concentrate specifically on these muscles. In man, ability to achieve
full extension of the knee is a desired endpoint, however, due to the functional
angle of the dog’s knee, this is less important.
Listed below are post-operative cruciate repair TE exercises:
1. Sit/stand.
2. Corner stands.
3. Figure of 8/circle walks.
4. Wheel barrelling.
5. E-stim. of hamstrings/quads.
6. U.S./stretching of hamstrings, quads.
7. Initial decline treadmill followed by incline treadmill.
8. Leg weights.
9. Enhancement of proprioception—unbalancing.
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Shock Wave Therapy Can Help Promote Bone Healing and
Reduce Pain
Shock wave therapy is a treatment
that is increasingly used by veterinarians to treat orthopedic problems
such as bone fractures and navicular disease. According to Dr. Christopher
Byron at the University of Illinois Veterinary Teaching Hospital in Urbana,
shock wave therapy can promote bone growth and healing, and minimize pain.
Contrary to what its name implies, shock wave therapy does not use electrical
pulses, but rather high energy acoustic pulses, much like sound waves,
that have the ability to travel readily through soft tissues to affect
hard material and tissues such as mineralized deposits or bone.
A shock wave unit consists of a box that generates the acoustic waves
connected to a wand that can be held up to the body to target the waves to
a specific site of treatment.
Dr. Byron explains, "This therapy has been used in both human and veterinary
medicine for many years, but we are discovering new applications for this
treatment."
Shock wave therapy was originally used in veterinary medicine to break
up kidney stones. Since the acoustic waves can travel through soft tissue,
when these waves are directed toward the kidney, they pass right through
muscle and kidney tissues. Once these waves meet something hard like a
kidney stone, they can fracture the stone apart. Breaking up kidney stones
into smaller fragments allows them to be passed through the urine, often
eliminating the need for surgical removal of the stones.
Veterinary practitioners have recently discovered more uses for shock
wave therapy. Since the acoustic waves can travel through soft tissue and
affect hard materials, they can be used to target bones. For bone fractures
that aren't healing well in dogs and cats, or for stress fractures in horses,
shock wave therapy using low doses of acoustic waves can enhance bone growth
and healing two ways: by stimulating osteoclasts, the bone cells that rebuild
the bone, and by enhancing the development of new blood vessels.
At the University of Illinois teaching hospital, Dr. Byron explains that
shock wave therapy is most commonly used to treat ligament problems in
horses. Athletic horses can suffer inflammation of the suspensory ligament
in the front leg, and shock wave therapy has been effective in reducing
pain and promoting healing of this ligament.
Dr. Byron has also studied how shock wave therapy can be used to treat
navicular disease, a common heel condition in horses. He found that when
used with corrective shoeing, shock wave therapy can alleviate some lameness
in the short term.
In addition to providing healing and anti-inflammatory properties, shock
wave therapy works two ways to reduce pain. Its anti-inflammatory action
reduces the amount of inflammatory biochemicals that cause pain. "In addition,
this therapy seems to temporarily disrupt nerve impulse transmission," thus
reducing the perception of pain, Dr. Byron explains. These pain reducing
properties can be very useful for treating dogs and horses with arthritis.
Dr. Byron points out that shock wave therapy in not a universal remedy
for any orthopedic condition. "It has definite benefits, but the therapy
is most effective when used in conjunction with other treatments," such
as medical treatment, corrective surgery or shoeing, and rehabilitative
physical therapy.
"Orthopedic treatment is still a relatively new application of this technology.
We're still discovering potential uses for this therapy."
For more information about shock wave therapy, consult your veterinarian.
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The above information is simply informational.
It's intent is not to replace the advice of a veterinarian nor to assist you
in making a diagnosis of your pet. Please consult with your own veterinarian
for confirmation of any diagnosis. Your pets life may depend on it.
