5.2 Therapeutic Modalities
Key Takeaways
- Cryotherapy (cold): reduces pain, spasm, inflammation, and metabolic rate; applied for 10-20 minutes; contraindicated in Raynaud disease, cold hypersensitivity, and impaired sensation
- Thermotherapy (superficial heat): increases blood flow, tissue extensibility, and metabolic rate; applied for 15-20 minutes; contraindicated over malignancy, acute inflammation, and impaired sensation
- Ultrasound (thermal): continuous mode at 1-2 W/cm2 increases tissue temperature; used to improve joint extensibility before stretching; contraindicated over growth plates, eyes, reproductive organs, and implants
- Diathermy (shortwave): deep heating modality using electromagnetic energy; heats tissues 3-5 cm deep; contraindicated with metal implants
- Mechanical traction (cervical): intermittent traction at 25-35 lbs or 10-15% body weight for disc herniation; contraindicated in ligamentous instability, VBI, malignancy, and RA with atlantoaxial instability
- Mechanical traction (lumbar): intermittent traction at 50-65% body weight for disc conditions; sustained traction at 25% for muscle spasm
- Hydrotherapy: water temperature ranges from cool (79-92F) for exercise to warm (92-98F) for pain/stiffness; hot (98-104F) for chronic conditions; contraindicated with open wounds in whirlpool (cross-contamination risk)
- Iontophoresis uses direct current to drive ions of medication through the skin: dexamethasone (negative pole, anti-inflammatory) and lidocaine (positive pole, anesthetic)
Physical therapy modalities are used as adjuncts to therapeutic exercise and manual therapy. The NPTE heavily tests the indications, contraindications, parameters, and physiological effects of each modality.
Thermal Agents
Cryotherapy (Cold)
| Method | Application Time | Depth of Penetration |
|---|---|---|
| Ice pack/cold pack | 10-20 minutes | Superficial (1-2 cm) |
| Ice massage | 5-10 minutes (or until numbness) | Superficial |
| Cold whirlpool | 10-20 minutes | Superficial to moderate |
| Vapocoolant spray | Seconds (spray and stretch) | Skin surface only |
Physiological Effects:
- Vasoconstriction → decreased blood flow → decreased inflammation and edema
- Decreased nerve conduction velocity → pain relief
- Decreased muscle spindle firing → reduced spasm
- Decreased metabolic rate → reduced secondary injury
Contraindications:
- Raynaud disease or phenomenon
- Cold hypersensitivity or cold urticaria
- Cryoglobulinemia
- Impaired sensation (risk of frostbite)
- Over open wounds (ice pack only — cold whirlpool may be appropriate)
- Peripheral vascular disease (compromised circulation)
Superficial Heat
| Method | Application Time | Depth |
|---|---|---|
| Hot pack (hydrocollator) | 15-20 minutes | 1-2 cm (superficial) |
| Paraffin wax | 15-20 minutes (dip-wrap or immersion) | 1 cm (superficial); excellent for hands, feet |
| Fluidotherapy | 15-20 minutes | 1-2 cm; dry heat |
| Warm whirlpool | 15-20 minutes | Superficial to moderate |
| Infrared | 15-20 minutes | Superficial |
Physiological Effects:
- Vasodilation → increased blood flow → promotes healing
- Increased tissue extensibility → improved stretching effectiveness
- Decreased pain via gate control mechanism
- Increased metabolic rate → promotes tissue repair
- Decreased muscle spasm
Contraindications (ALL heat modalities):
- Acute inflammation or trauma (first 48-72 hours)
- Over malignancy
- Impaired sensation
- Impaired circulation (PVD)
- Active hemorrhage or bleeding disorders
- Over the eyes, reproductive organs, growth plates
Deep Heating Modalities
Therapeutic Ultrasound Parameters Summary
| Parameter | Thermal Mode | Non-Thermal Mode |
|---|---|---|
| Duty cycle | Continuous (100%) | Pulsed (typically 20%) |
| Intensity | 1.0-2.0 W/cm2 | 0.5-1.0 W/cm2 |
| Frequency | 1 MHz (deep) or 3 MHz (superficial) | 1 or 3 MHz |
| Duration | 5-10 minutes per area | 5-10 minutes per area |
| Primary effects | Tissue heating, improved extensibility | Cavitation, acoustic streaming, tissue repair |
| Best used | Before stretching contractures, chronic conditions | Acute injuries, wound healing, fracture healing |
Ultrasound Contraindications:
- Over the eyes, heart, brain, reproductive organs
- Over growth plates (epiphyseal plates) in children
- Over malignancy
- Over spinal cord after laminectomy
- Over joint cement or plastic components (thermal mode)
- Over thrombophlebitis/DVT
- Pregnancy (over abdomen/pelvis)
Shortwave Diathermy
- Deep heating using electromagnetic energy (shortwave radio frequencies)
- Heats tissues to 3-5 cm depth (similar to 1 MHz ultrasound)
- Particularly effective for heating large tissue volumes
- Absolute contraindication: metal implants (internal or external) — electromagnetic energy heats metal rapidly
- Also contraindicated over pacemakers, pregnancy, malignancy, and areas with impaired sensation
Mechanical Modalities
Traction
| Type | Cervical | Lumbar |
|---|---|---|
| Force | 25-35 lbs (or 10-15% body weight) | 50-65% of body weight |
| Disc conditions | Intermittent: 15 sec on, 5 sec off | Intermittent: 15 sec on, 5 sec off |
| Muscle spasm | Sustained: lower force, longer hold | Sustained: 25% body weight |
| Position | 25 degrees cervical flexion (foraminal opening) | Prone or supine; hook-lying reduces lordosis |
| Duration | 15-20 minutes | 15-20 minutes |
Traction Contraindications:
- Ligamentous instability
- Vertebrobasilar insufficiency (VBI) — for cervical
- Rheumatoid arthritis with atlantoaxial instability
- Malignancy in the spine
- Acute disc herniation with progressive neurological deficit
- Osteoporosis (severe)
- Pregnancy (lumbar)
- Untreated hypertension
Iontophoresis
Iontophoresis uses direct current (DC) to drive charged medication ions through the skin:
| Medication | Charge/Polarity | Purpose |
|---|---|---|
| Dexamethasone | Negative (-) | Anti-inflammatory (tendinopathy, bursitis) |
| Lidocaine | Positive (+) | Local anesthetic (pain relief) |
| Acetic acid | Negative (-) | Calcium deposits (calcific tendinitis) |
| Salicylate | Negative (-) | Anti-inflammatory |
Rule: The medication is placed under the electrode with the same charge (like charges repel, driving the ions into the tissue).
Intermittent Pneumatic Compression
Intermittent pneumatic compression (IPC) uses an inflatable sleeve to mechanically reduce edema and assist venous and lymphatic return. Typical inflation pressures are roughly 30-60 mmHg for the upper extremity and 40-80 mmHg for the lower extremity, kept below the patient's diastolic blood pressure to avoid impeding arterial flow. IPC is indicated for venous insufficiency, lymphedema (as an adjunct to manual lymphatic drainage), and DVT prophylaxis.
Key contraindications mirror the danger of moving fluid or a clot centrally: acute DVT, acute pulmonary edema, uncompensated congestive heart failure, and acute infection in the limb. As with compression bandaging, coexisting significant arterial disease (a low ABI) is a contraindication.
Biophysical Agent Decision-Making
The NPTE rewards matching the agent to the tissue phase. During the acute inflammatory phase (first 24-72 hours), choose cold to limit secondary injury and edema; heat is contraindicated. During the chronic phase, heat and continuous ultrasound increase extensibility before stretching contractures, while pulsed (non-thermal) ultrasound and electrical stimulation support tissue repair. The classic sequence to maximize a stretch is heat (or thermal ultrasound), then stretch while the tissue is warm, then ice in the lengthened position to "set" the gain.
Universal Contraindications and Safety Checks
Several contraindications recur across nearly every modality and are heavily tested: impaired sensation, impaired cognition/inability to report, impaired circulation, malignancy, over the abdomen/pelvis during pregnancy, and over an active DVT or area of acute hemorrhage. Electromagnetic agents (shortwave diathermy) add pacemakers and any metal as absolute contraindications.
Before any thermal or electrical modality, the PT confirms intact sensation, inspects the skin, screens for contraindications, and re-checks the area during and after treatment. A frequent test trap is selecting an effective modality for a patient who has a contraindication to it — the contraindication always overrides the indication, because patient safety is the governing principle of modality application.
Which of the following is a contraindication for the application of superficial heat?
When performing cervical traction for a patient with cervical disc herniation, the recommended force is:
In iontophoresis, dexamethasone (a negatively charged medication) would be placed under which electrode?
Shortwave diathermy is ABSOLUTELY contraindicated in patients with:
Which of the following are contraindications for therapeutic ultrasound? (Select all that apply)
Select all that apply
A patient with Raynaud disease would have a contraindication to which modality?
For lumbar disc herniation, the recommended intermittent mechanical traction force is:
Pulsed ultrasound at 20% duty cycle is MOST appropriate for:
Paraffin wax is MOST commonly used for treating: