EB

Cryotherapy and Thermotherapy Comprehensive Study Notes

Tissue Layers, Depth, and Energy Penetration

  • Superficial tissue interface ≈ 1 cm deep
    • Skin, cutaneous vessels, superficial nerves, minimal muscle involvement
  • Deep-tissue interface ≈ 2 cm deep
    • Sub-cutaneous adipose, superficial portions of muscle/tendon, delivery vessels
  • Clinical significance
    • Choose modality whose known depth of penetration matches target tissue
    • Physics limits depth; e.g., ice massage ≈ 1 cm, cold whirlpool ≈ 2 cm, diathermy/US reach deeper

Cryotherapy – Analgesic & Physiological Mechanisms

  • Gate-control: stimulate A-β mechanoreceptors → inhibit A-δ/C nociceptors
    • “Bag of M&M’s” metaphor → any sensory barrage can close the gate
  • Neural conduction velocity ↓ in ALL peripheral fibers
    • A-δ/C ↓ ⇒ pain slower
    • A-α/A-β ↓ ⇒ motor & proprioceptive slowing (but not abolished)
  • Metabolic slowdown
    • ↓ ATP use → ↓ O_2 demand → ↓ secondary hypoxic death
    • Clinical analogy: cryogenic preservation / clot-busting window in ischemic stroke
  • Hemodynamic changes
    • Immediate vasoconstriction, ↑ viscosity
    • ↓ leukocyte diapedesis & prostaglandin synthesis (limits edema, pain)
    • Excess cooling (<56 °F) triggers Hunter’s (hunting) response → reflex vasodilation, red/purple skin

Cold Sensation Sequence (C-B-A-N)

  1. Cold
  2. Burning
  3. Aching
  4. Numbness (analgesia)

Therapeutic Temperature & Time Targets

  • Analgesia threshold: 58^{\circ}F (14.4 °C) skin temperature
  • Max blood-flow modulation: 57^{\circ}F (13.9 °C)
  • <56^{\circ}F (13.3 °C) → Hunter’s response
  • Standard application
    • Ice bag / GameReady etc.: 20–30 min, every 90 min (tissue re‐warms ≈ 90 min)
    • Ice massage: 5–10 min (small area, direct contact)
    • Cold whirlpool: 50–60 °F (10–15 °C) for 10–15 min (agitated)
    • Slush bucket: 40–50 °F (4–10 °C) for 15–20 min (stagnant)

Cryotherapy Precautions

  • Pad over superficial nerves
    • Common fibular (fibular head), ulnar (medial elbow), facial branches, etc.
  • Hypertension (cold ↑ BP), psychological intolerance, exercise with pack (lose spindle input)

Cryotherapy Contraindications

  • Absent/altered sensation, cold hypersensitivity/urticaria
  • Raynaud’s phenomenon, cryoglobulinemia, paroxysmal cold hemoglobinuria
  • Severe cardiovascular/respiratory disorders, uncontrolled hypertension
  • Open wounds, infection, circulatory compromise, peripheral neuropathy
  • Rheumatoid/advanced arthritic flare (deep structures out of reach)

Cold Modalities & Clinical Points

  • Ice bag (true ice)
    • Moldable; six-week-freezer ≈ 32^{\circ}F; remove gross air, secure with elastic wrap
  • Reusable gel pack
    • Stored below 0 °F; must insulate (towel) to avoid freezer burn
  • Instant chemical pack
    • Ammonium‐nitrate rupture → cold; risk chemical leak/burn; short life
  • Cold-compression device (GameReady®, DonJoy®)
    • Adjustable temp & pneumatic compression; expensive, insurance may cover post-op
  • Water immersion
    • Slush bucket (static) vs cold whirlpool (agitated)
    • Agitation ↑ convective cooling → higher temp + shorter time
  • Ice cup massage
    • Paper/styrofoam cup, tear rim; can use edge for IASTM-like sweeping
    • Not for acute muscle tear (pressure-pain)
  • Contrast bath (hot↔cold)
    • Typical 3 : 1 or 4 : 1 hot:cold minute ratio, 20 min total
    • Limited evidence for edema clearance; still common anecdotally

Cryokinetics (Ice + Exercise)

  • Sequence: 20 min ice → immediate pain-free exercise (2–5 min) → re-ice
  • Goals
    • Maintain ROM, proprioception, strength during acute phase
    • Break pain–spasm cycle while allowing movement
  • End session with exercise if athlete returns to practice; with ice if not

Thermotherapy – Mechanisms

  • Therapeutic tissue range 104^{\circ}F–113^{\circ}F (40–45 °C)
    • >113^{\circ}F risks protein denaturation / burns
  • Local effects
    • ↑ metabolic rate, vasodilation, capillary permeability
    • ↑ nerve conduction velocity, ↓ muscle spindle activity, ↓ γ-gain
    • ↑ collagen extensibility → plastic deformation (stretch, manual therapy)
  • Systemic effects (large-area / immersion)
    • ↑ HR & RR to meet O_2 demand
    • ↓ BP (widespread vasodilation)
  • Axon reflex + spinal sympathetic reflex mediate cutaneous vasodilation
  • Time course
    • 0–6 min: rapid tissue heating (check skin!)
    • 7–9 min: rate slows
    • 15–20 min: peak temp
    • >20 min: rebound vasoconstriction begins

Thermotherapy Indications

  • Sub-acute → chronic stage; post-inflammatory stiffness
  • Increase ROM, prep for stretch/manual, decrease pain-spasm cycle
  • Facilitate blood/lymph flow, promote waste removal, relieve chronic edema

Thermotherapy Precautions & Contraindications

Precautions

  • Elderly, pediatric, medically unstable; diminished thermal regulation
  • Superficial metal implants/jewelry; MOLTING (excess moisture → skin maceration)
    Contraindications
  • Acute inflammation/hematoma, open wound without covering
  • Heat illness/fever, impaired sensation, thrombophlebitis/DVT
  • Active hemorrhage, unknown mass or confirmed neoplasm
  • Severe cardiac disease, coagulation disorders (e.g., hemophilia)

Heat Modalities & Parameters

Hydrocollator Hot Pack

  • Stored at 170^{\circ}F (~77 °C)
  • Six protective layers: terry cover (4) + folded towel (2)
  • Position pack ON TOP of body (gravity), 20 min typical
  • No weights; inspect skin at 5 min; major source of PT malpractice (burns)

Whirlpool (warm‐water)

  • Temperatures (larger area → lower setting)
    • Hand/wrist 112^{\circ}F
    • Foot/ankle 110^{\circ}F
    • Elbow 108^{\circ}F
    • Knee 106^{\circ}F
    • Thigh 104^{\circ}F
  • 15–20 min; monitor systemic vitals (HR, BP)

Paraffin Bath

  • Mix paraffin + mineral oil → melt point 118^{\circ}F
  • Unit kept 125–127^{\circ}F
  • Dip–air-dry 4–6× → glove → plastic bag → towel wrap; 20–30 min
  • Best for hands; feet discouraged (hygiene)

Fluidotherapy

  • Circulating cellulose (corn-husks) at 110–125^{\circ}F
  • UE dominant (hand, wrist, elbow); allows AROM inside unit
  • Messy ― fine powder coats limb & floor

Analgesic Balms / Counter-Irritants

  • Menthol, capsaicin, methyl-salicylate cause sensation of heat/cold without true temp change
  • Adjunct; do NOT place hot pack over balm (risk burn)

Heat Lamps / IR

  • Inefficient; dries skin; largely outdated

Whole-Body vs Local Warm-Up

  • Dynamic, systemic exercise elevates core temp, delivers heat via circulation → deeper, longer-lasting effects than local packs
  • Local heat still valuable for focal pliability just before stretching/manual work

Other Pain & Inflammation Management Mentioned

  • Pharmacologic
    • Acetaminophen (analgesic)
    • NSAIDs (inhibit prostaglandins)
    • Corticosteroids (block arachidonic acid cascade)
  • Electrotherapy: TENS (endogenous opioids), central biasing (cognitive)

Key Numbers & Formulas to Retain

  • Analgesic skin temp: \le 58^{\circ}F
  • Hunter’s response threshold: \le 56^{\circ}F
  • Hydrocollator tank: 170^{\circ}F
  • Therapeutic heat window: 104^{\circ}F \rightarrow 113^{\circ}F
  • Ice application: 20–30 min, tissue returns baseline ≈ 90 min
  • C-B-A-N timeline: typically 0–3 min cold → 2–7 min burning → 5–12 min aching → ≥12 min numb (varies)

Clinical Decision-Making Summary

  • Match modality to depth, stage, and goal (pain vs metabolism vs extensibility)
  • Monitor temp, time, skin condition every treatment
  • Understand precautions/contraindications; ask history every new patient
  • Use systemic warm-ups and cryokinetics to integrate therapeutic exercise
  • Educate patients on home use (20 min on/90 min off; no chemical packs on skin; protect nerves)