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