Shockwave Therapy in Horses

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Overview of shockwave therapy for musculoskeletal injuries in the horse.

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  • Variables: pressure, energy level, frequency, depth of penetration, quantity of pulses applied
  • Adams reference 6, 4, and 11
  • In the early phase of tissue repair, TGFβ-1 has a proinflammatory action and also modulates the deposition of extracellular matrix com- ponents and enhances collagen, fibronectin, and gly- cosaminoglycan synthesis from fibroblasts.16 Wang et ala have suggested that one of the possible mechanisms of action of ESWT is mediated through the action of TGFβ-1.
  • Shockwave Therapy in Horses

    1. 1. SHOCKWAVE THERAPY FOR MUSCULOSKELETAL INJURIES IN THE HORSE Dane Tatarniuk, DVM September 11, 2013
    2. 2. Overview:  Case Description  Review of Shockwave Therapy  Review of Research Papers
    3. 3. Case Descriptions
    4. 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. 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. 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. 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. 8. Nuclear Scintigraphy: Marked radiopharmaceutical uptake in the lower tarsal joints, bilaterally
    9. 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. 10. Radiographs: L R - Central and third tarsal bone sclerosis noted on radiographs. - ie, bone bruising - More apparent on the medial aspect.
    11. 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. 12. Shockwave Overview
    13. 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. 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. 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. 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
    17. 17. 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
    18. 18. 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)
    19. 19. 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
    20. 20. 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
    21. 21. 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
    22. 22. 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
    23. 23. Shockwave Research
    24. 24. 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
    25. 25. 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?
    26. 26. 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
    27. 27. 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
    28. 28. 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-
    29. 29. 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
    30. 30. 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
    31. 31. 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)
    32. 32. 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
    33. 33. 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
    34. 34. 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
    35. 35. 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)
    36. 36. 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
    37. 37. 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
    38. 38. Overview
    39. 39. 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

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