PHT 5216: Unit 2 – Cryotherapy Study Guide

🔹 Definition and Purpose

Cryotherapy is the local application of cold to the body to reduce tissue temperature and manage acute musculoskeletal injuries, pain, or inflammation.

Key Goals:

Reduce tissue temperature through heat transfer.

Lower metabolic rate, pain, and swelling.

Prevent secondary hypoxic injury following trauma.

🔹 Mechanisms of Heat Transfer

Mechanism Description Examples

Conduction Heat transfers between molecules of warmer and cooler areas by direct contact. Ice packs, ice massage, Game Ready unit

Convection Heat is transferred through fluid or air movement. Cold whirlpool, air fan

Evaporation Conversion of liquid to vapor extracts heat from skin. Vapocoolant sprays (Biofreeze, Cold Spray)

Radiation Infrared energy transfer (covered later in course). Sunlight, infrared lamp

🔹 Factors Affecting Tissue Cooling

Temperature Gradient – Greater difference = faster cooling.

Duration of Exposure – Longer duration = deeper cooling.

Thermal Conductivity – Muscle (high water) cools faster than fat.

Type of Cooling Agent – Ice (phase change) absorbs more heat than gel packs.

Clinical Example:

TKA vs. Obese Patient: Thicker adipose tissue limits cooling depth; longer or colder applications may be required.

🔹 Physiological Effects of Cryotherapy

System Effect Clinical Significance

Circulatory Vasoconstriction → ↓ blood flow, ↑ viscosity Limits edema and inflammation

Metabolic ↓ metabolic rate and O₂ demand Prevents hypoxia and secondary cell death

Neuromuscular ↓ nerve conduction velocity (NCV) Reduces pain and spasticity

Reflex Effects ↓ γ-motor neuron activity, ↓ muscle spindle discharge Beneficial in CNS disorders (CVA, CP, MS)

Hunting Response:

Below 10°C (50°F) → alternating vasoconstriction and vasodilation cycles.

🔹 Clinical Indications

Acute musculoskeletal trauma

Post-surgical swelling/pain

Pain and muscle spasm reduction

Myofascial pain or trigger points

DOMS

Tendinitis, bursitis, tenosynovitis

🔹 Rationale in Acute Injury

Primary Goal: Prevent secondary hypoxic injury by reducing:

Blood flow and metabolism

Release of inflammatory chemicals

Hemorrhage and edema formation

Note: Cryotherapy does not eliminate edema entirely or stop the necessary inflammatory process.

🔹 PRICE Principle (24–48 hrs Post-Injury)

Protect: brace, tape, or assistive devices

Rest: avoid stress or re-injury

Ice: reduce blood flow, metabolic demand

Compress: limit fluid escape

Elevate: reduce hydrostatic pressure

🔹 Controversies

Prolonged icing may delay recovery or cause nerve damage (Wang & Ni, 2021).

However, short-term use remains beneficial for severe swelling and pain management.

🔹 Analgesic Effects (Pain Relief)

Reduced NCV: Slows nociceptive input.

Gate Control Theory: Cold receptor stimulation blocks pain signals at spinal cord.

⚠ Caution: Analgesia may mask pain—avoid strenuous activity for 1–2 hours post-treatment.

🔹 Neuromuscular Effects

↓ muscle performance after ≥10 minutes of cooling.

↓ proprioception (joint position sense, balance).

Beneficial ↓ in spasticity for neurological conditions (CVA, CP, MS).

🔹 Common Cryotherapy Modalities

Modality Temperature / Duration Notes

Commercial Cold Pack < 32°F; 15–20 min Use towel/pillowcase barrier; compression increases cooling.

Ice Bag ~32°F; 15–20 min Crushed ice molds better to body; thin barrier optional.

Ice Massage 5–10 min Small area; circular strokes; stop when numb/blanched.

Cold Immersion Bath 50–65°F (extremity) / 65–80°F (whole body); 10–20 min Convection effect; avoid dependent limb position.

Cold Compression Unit (e.g., Game Ready) Continuous circulation Combines cooling + compression; manual or electric.

Vapocoolant Spray (“Spray & Stretch”) Hold 12 in away; 5–8 sec Skin temp drops to 59°F; used before stretching trigger points.

🔹 Cryotherapy Sensation Cycle (C-B-A-N)

Occurs within ~5 minutes:

Cold

Burning

Aching

Numbness

🔹 Treatment Procedure

Explain procedure, benefits, and C-B-A-N sensations.

Obtain patient consent.

Position and support body part; elevate if needed.

Secure modality; provide call bell.

After treatment, check skin color:

Normal: Redness (due to oxygen-rich venous blood & reactive hyperemia).

Abnormal: Pale, blotchy, or grayish—stop and reassess.

🔹 Precautions

Hypertension: Monitor BP (cold raises BP).

Cold sensitivity: Test small area; add towel layer if needed.

Impaired sensation/cognition: Monitor closely.

Superficial nerves (e.g., peroneal): Avoid direct application.

Young/elderly: Modify for tolerance.

🔹 Contraindications

Condition Effect / Risk

Cold urticaria Hives, itching, rash 24–48 hrs post-treatment

Cryoglobulinemia Abnormal proteins block vessels → ischemia

Raynaud’s phenomenon Arterial spasm → ↓ blood flow to digits

Paroxysmal cold hemoglobinuria RBC breakdown → hemoglobin in urine

Compromised circulation / PVD Risk of ischemia/gangrene

Nerve regeneration area Delayed healing

History of frostbite or Buerger’s Disease Tissue ischemia

Severe cardiovascular/respiratory disorders Stress intolerance

🔹 Outcome Measures

Edema: Girth or volumetric measurements

Pain: Visual Analog Scale (VAS)

ROM: Goniometry

Function: Gait, AROM, muscle guarding observation

🔹 Documentation

Include:

Patient position / body part

Modality type and parameters (temp, time)

Number of barrier layers

Tissue and patient response

Pre-/post-treatment outcomes