Overview of shockwave therapy for musculoskeletal injuries in the horse.

1. SHOCKWAVE THERAPY
FOR MUSCULOSKELETAL INJURIES IN
THE HORSE
Dane Tatarniuk, DVM September 11,
2013

2. Overview:
 Case Description
 Review of Shockwave Therapy
 Review of Research Papers

3. Case Descriptions

4. 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

5. 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

6. 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

7. 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

8. Nuclear Scintigraphy:
Marked radiopharmaceutical uptake in the lower tarsal joints,
bilaterally

9. Radiographs:
L
- Moderate
ankylosis of left
distal inter-
tarsal joint
- Mild
osteoarthritis in
right distal inter-
tarsal
- Bilateral tarsal
meta-tarsal
joints
unremarkable

10. Radiographs:
L R
- Central and third
tarsal bone
sclerosis noted
on radiographs.
- ie, bone bruising
- More apparent
on the medial
aspect.

11. 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

12. Shockwave Overview

13. 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

14. 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

15. 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

16. 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

18. 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

19. 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)

20. 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

21. 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

22. 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

23. 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

24. Shockwave Research

25. 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

26. 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?

27. 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

28. 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

29. 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-

30. 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

31. 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

32. 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)

33. 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

34. 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

35. 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

36. 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)

37. 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

38. 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

39. Overview

40. 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