Shockwave Therapy in Horses
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Transcript of Shockwave Therapy in Horses
SHOCKWAVE THERAPYFOR MUSCULOSKELETAL INJURIES IN
THE HORSE
Dane Tatarniuk, DVM September 11, 2013
Overview:
Case Description Review of Shockwave Therapy Review of Research Papers
Case Descriptions
Case Description:
9 year old American Paint Horse gelding, discipline is western pleasure Presenting complaint: Sore back, poor performance during the western
lope Previous veterinary diagnostics
Bilateral tarsus radiographs from 2 years ago Bilateral stifle radiographs from 2 years ago
Flattening of the medial femoral condyle, bilaterally Thoracolumbar radiographs from 1 month ago
No evidence of overriding dorsal spinous process Previous veterinarian therapeutics
Bilateral hock injections Corticosteroids + HA
Bilateral stifle injections HA only
Sacroiliac injection Corticosteroids
Right front bicepital bursa injection Mesotherapy Methocarbamol (50mg/kg)
Lameness Evaluation
Passive examination Negative hoof testers bilaterally Mild church hill response bilaterally Conformation
Straight legged in hind with sickle & cow hock conformation
Feet Egg bar shoe both fronts, mild frog atrophy
Neck & Back Hypereasethetic response along neck musculature Withdrawal response to palpation of caudal thoracic &
lumbar epaxial musculature
Lameness Evaluation
Passive examination No medial patellar ligament palpated, right hind
Previous desmotomy? Asymmetric musculature in hind end, with
generalized reduced muscle mass in right hind
Active examination, baseline Grade 2/5 right hind Grade 1/5 left front Grade 1/5 right front
Lameness Evaluation
Active examination, baseline On soft surface, left & right circle
Forelimbs: no change from baseline Right hindlimb: slight increase in right hindlimb lameness
On hard surface, left & right circle Right hindlimb: increased, noted by toe dragging and
reduced cranial phase of stride
Flexions Forelimb flexions – all negative Hindlimb flexions
Distal limbs – negative Upper limbs – mild positive bilaterally Abduction & adduction – mild positive, right hind
Nuclear Scintigraphy:
Marked radiopharmaceutical uptake in the lower tarsal joints, bilaterally
Radiographs:
L
- Moderate ankylosis of left distal inter-tarsal joint
- Mild osteoarthritis in right distal inter-tarsal
- Bilateral tarsal meta-tarsal joints unremarkable
Radiographs:
L R
- Central and third tarsal bone sclerosis noted on radiographs.
- ie, bone bruising
- More apparent on the medial aspect.
Therapy:
Intra-articular injection Bilateral tarsal metatarsal & distal intertarsal joints
40mg methyprednisolone, 10mg hyaluronic acid Right hind medial femoral tibial joint
6mg triamcinolone, 20mg hyaluronic acid Continue with methocarbamol therapy Initiate course of phenylbutazone Recommended chiropractic adjustment Shockwave applied to central & third tarsal
bones Provide analgesia and stimulate bone remodeling 1500 pulses, 8Hz, per side
Shockwave Overview
What is Shockwave?
“Extracorporeal shockwave therapy” def: ‘Extracorporeal’
Acoustic waves generated outside the body
Transient high peak pressures alternating with negative pressure Varies with machine type and
settings Wave rise time of 5 to 10
nanoseconds Maximum peak pressure of 20 to
100 megapascals 1 megapascal is 10x that of
atmospheric pressure
Shockwave Generators
Variables: pressure, energy level, frequency, depth of penetration, quantity of pulses applied
Two broad categories of shockwave generation 1) ‘Focused’ shockwave 2) ‘Radial’ shockwave
Focal volume: area affected by the shockwave With energy constant,
Smaller focal volume = more energy concentrated Large focal volume = energy spread over greater area
Shockwave Generators
Generator types Focused shockwave
1) Piezoelectric generators High current excites crystals which then produces a pressure
wave Small focal volume, high energy flux, low overall energy transfer
2) Electromagnetic generators High voltage current transfer through a coil, which propels a
diaphragm, creating a pressure wave Small focal volume, high energy flux, less concentrated (vs. piezo)
3) Electrohydraulic shockwave Pass high voltage through a spark gap in a fluid filled ellipsoid
reflector Expanding plasma & gas bubbles create pressure wave Large focal volume, low energy flux, overall high energy transfer
Shockwave Generators
Generator types cont… Radial shockwave
Also known as ‘ballistic’ Doesn’t have rapid rise time or high energy typical of
shockwave Uses mechanical concussion No focusing system
Energy of wave declines in proportion to distance from source
Mechanism of Action:
Not entirely understood
Shockwave energy has similar physics as sound waves Acoustic impedance
Amount of wave energy transmitted into tissue depends on the difference in impedance between two tissue types
Impedance = wave pressure (p) / wave velocity (v) Tissues with…
air-fluid interface absorb greatest amount of energy Lower acoustic impedance
muscle-fat interface absorb least amount of energy Higher acoustic impedance
Near lungs Induce pleural hemorrhage
Mechanism of Action:
When the shock wave meets an interface of different impedance… Pressure and shear forces occur Development within fluid media of cavitation bubbles
Collapse & expand Large amount of energy released when bubble implodes
Is it this mechanical mechanism at work?
Pressure waves effect on cells (in-vitro): Bone remodeling
Induce production of nitric oxide (Wang 2003) Cytostimulation
Increase concentrations of TGF-Β (Wang 2000) Increased concentration of osteocalcin (Wang 2000) Increased osteocyte cell division (Wang 2000)
Stimulation of endochondral ossification Increase in extracellular matrix proteins (Takahaski 2001)
Analgesic
Provides pain relief Likely largest reason therapeutic contributes to positive clinical
outcome for the client Dramatic decrease for 3 to 4 days resurgence of pain gradual
decrease after 3 to 4 weeks Studies have shown decreased nerve conduction following
shockwave application Bolt 2004, McClure 2005. Disruption of myelin sheath with no evidence of damage to
Schwann cell bodies or axons Concern that analgesia may reduce or eliminate pain, that
could lead to catastrophic injury with continued exercise Too high of energy has been shown to induce micro-cracks in
dorsal cortical surface of MC3 Withdrawal time of 5-7 days prior to performing
Racing jurisdictions, FEI
Application
General rule is that a good ultrasound image can be attained of the injury, then shockwave energy can reach the depth of the tissue
Once shockwave pulse hits bone, approximately 65% transmitted (and 35% reflected) Approximately 80-90% reduction of energy by 1-
2cm of bone Sedation apply ultrasound gel to target area
perform shockwave therapy Often multiple series of shockwave sessions,
separated by 2-3 week intervals
Clinical Use:
Urinary Lithotripsy
Musculoskeletal: Desmitis / Tendonitis
Proximal Suspensory Ligament Distal sesamoidean Ligaments DDFT / SDFT / Check Ligament Collateral Ligaments
Osteoarthritis Distal Tarsal OA Proximal Interphalangeal OA Navicular disease
Bucked shins Tibial stress fractures Proximal sesamoid fractures Sore back musculature Impinging dorsal spinous
processes Subchondral bone pain Angular limb deformities Wounds
Complications
Dose dependent action, but generally very safe Too little energy = no effect Too much energy = damage tissues
In bones, Micro-fracture of cortical bone Medullary hemorrhage Sub-periosteal hemorrhage
In tendons, Hematoma formation Tendon cell damage
Generally attempt to avoid large vessels Avoid active physis
Unless treating A.L.D. Avoid neoplastic or infected tissue
Metastasis or spread of sepsis
Shockwave Research
Historical Use
First utilized for lithotripsy in humans 25 years ago
Graff, 1986 Shockwave induced up-regulation
of osteoblast cells Haupt, 1991
Increased healing time of humeral fractures in rats
Human medicine Lateral epicondylitis (tennis elbow Plantar calcaneal spurs (heel spurs)
First clinical report in animals in 1999 Shockwave described as a
treatment for distal tarsal osteoarthritis
Research
Variable between studies Energy level, pulse frequency, depth of
penetration, number of treatments Type of injured tissue being treated
Conjunctive therapy Controlled exercise, NSAIDs, heat/cold
therapy, pressure wraps, platelet rich plasma, stem cells Skews interpretation Does shockwave therapy affect stem cells?
Research
Studied tendon-bone junction following shockwave 8 dogs 1000 pulses, 0.18mJ/mm2
One limb, biopsies compared to pre-shockwave sample Biopsies
Two blinded pathologists independently reviewed histology slides
Pre-shockwave in medial 1/3rd of Achilles tendon at 4 weeks in middle 1/3rd of Achilles tendon at 8 weeks in lateral 1/3rd of Achilles tendon
New capillary vessels seen in shockwave treated groups, none noted in control groups Present at 4 weeks, no further increase at 8 weeks No concurrent inflammatory cells
Arranged myofibroblasts seen in treated tendons No changes in osteocyte activity, bone matrix or
bone vascularity
Research
Dogs with unresolved stifle lameness treated with ECSWT or untreated controls
Determined force plate and range of motion measurements Baseline, every 3 weeks for 4 sessions, and 4 weeks following
final session Peak Vertical Force
4 of 7 dogs in ECSWT group improved 1 of 5 dogs in control group improved
Range of Motion 5 of 7 dogs in ECSWT group improved 3 of 5 dogs in control group improved
Research
24 dogs with hip osteoarthritis
18 received radial shockwave therapy; 6 controls
Force plate Prior to treatment 6 weeks after treatment 3 months after treatment 6 months after treatment
Significant improvement in peak vertical force & vertical impulse noted at all time points post-shockwave therapy
Research
Study 1: 4 horses with radiographically normal cannon bones One MC3
Control One MC3 & one MT3
1000 pulses of 0.89mJ/mm2
One MT3 1000 pulses of 1.8mJ/mm2
No damage to soft tissue structures Mild sub-periosteal and endosteal hemorrhage
Extending 1-2mm into the cortical bone Walls in the vessels of the osteon disrupted No micro-fractures appreciated
Osteogenesis Not likely due to microfractures Potentially due to bone marrow hypoxia, sub-periosteal hemorrhage,
increased regional blood flow, activation of osteogenic factors
Research
Study 2: 2 horses with radiographically normal cannon bones One MC3
Control One MC3 & MT3
2000 pulses of 0.89mJ/mm2
One MT3 Periosteum elevated to create mechanical irritation
Kept alive for 30 days, then euthanized Osteon activity evaluated by fluorescent microscopy Shockwave treated cannon bones:
Activated osteons New bone formation on periosteal & endosteal surface Shockwave limbs had 30% more activated osteons than control Shockwave limbs had 56% more activated osteons than
periosteal elevation
Research
n = 24 horses, distal radial carpal osteochondral fragment
3 groups of 8 horses Placebo (sham shockwave), positive control
(PSGAG IM q4days), or ECSWT (day 14 & 28) 2000 pulses, 0.14 mJ/mm2
Lameness scores in ECSWT group were significantly lower compared to placebo group (at day 28 & 70), and compared to PSGAG group (at day 70)
Reduced carpal flexion scores in ECSWT group vs. placebo/PSGAG group (at day 70)
Research
No significant differences in synovial fluid color, clarity, mucin clot formation, WBC counts between groups
Total protein and PGE2 lower in ECSWT & PSGAG group compared to placebo group
No difference between groups in gross pathologic scores (cartilage fibrillation, synovial membrane hemorrhage) or histologic scores (cellular infiltration, synovial intimal hyperplasia, subintimal edema/fibrosis/vascularity)
Improved lameness scores lasted up to 42 days after final treatment
Research
Four horses had suspensory ligament desmitis induced in both forelimbs using collagenase 1 ligament per horse treated with 3 sessions
of shockwave, 3 weeks apart 0.14 mJ/mm2, 1500 pulses
Ultrasound exams every 3 weeks (non-blinded)
Horses euthanized at 18 weeks for histology
Research
Fiber alignment score decreased faster in the shockwave treatment group compared to controls Score of 0 = normal, score of 3 =
25% or less No change in echogenicity Metachromasia
Occurs from proteoglycan deposition More focal in shockwave treated
ligaments Fibroblast & type 3 collagen
No difference
Research
6 healthy horses without lameness Shockwave therapy
Proximal suspensory, metacarpus Fourth metatarsal bone Opposing limb served as control 2000 pulses, 0.15mJ/mm2
Bone scans performed as baseline, and on day 3, 16, 19. Euthanasia for histopathology performed on day 30 No damage to soft tissue, no microfractures induced Shockwave significantly increased osteoblasts numbers Significant correlation between osteoblast numbers and
radiopharmaceutical uptake noted On day 3 & 16 for hindlimb On day 3 only for forelimb
Suggests shockwave increases osteoblast numbers Shortly after therapy (by 3 days)
Research
10 horses Collagenase injected into both forelimbs to create
suspensory desmitis 2 weeks after collagenase injection
Shockwave therapy, 1500 pulses, 0.15mJ/mm2
3 treatment sessions, separated by 3 weeks Greater amounts of small collagen fibrils present in
ECSWT group Represent new collagen fibril formation
(759 +/- 42) vs. (69 +/- 14)
Cytoplasmic staining in fibroblasts for TGFβ-1 Increased in ECSWT group compared to controls
Suggests rate of tissue repair in shockwave treated tissue is greater than tissue that does not receive therapy
Research
Naturally occurring forelimb lameness in 9 horses Baseline force plate values of
lameness, followed by force plate values following diagnostic analgesia
ECSWT performed 1000 pulses, 0.15mJ/mm2
Force plate 8 hours later, followed by daily force plate for 7 days
Peak Vertical Force PVF increased 8 hours & 2 days
following shockwave, and was not statistically different than previous diagnostic analgesia measurements
Vertical Impulse After 8 hours & 2 days VI increased,
but was statistically lower than previous diagnostic analgesia measurements
Overview
Overview
Shockwave is widely used in equine veterinary medicine There are various different types of shockwave
machines, which apply energy through different means The exact mechanism of how shockwave influences
healing is still relatively unknown Shockwave stimulates growth of cells, in-vitro Shockwave increases neovascularization and promotes
bone remodeling, in-vivo Shockwave provides immediate analgesia for the first 5-
7 days. This immediate analgesia then regresses. A second phase of analgesia is often seen 3-4 weeks thereafter.
Growing research to support the clinical application of shockwave for various injuries in the horse