Indication for ultrasound:

  • Soft tissue shortening (joint contracture, scarring, and adhesions).
  • Subacute and chronic inflammation.
  • Muscle guarding, sprain/strain, bursitis and tendonitis.
  • Tissue healing.
  • Edema (swelling) reduction.

Thermal effects:

  • Increased local temperature, metabolism, and blood flow.
  • Portion of energy from the ultrasound wave is absorbed into the tissue structure and converted into
    heat energy.
  • Amount of heating is determined by the frequency and intensity of the ultrasound.
  • Decrease local adhesion formation and nerve conduction velocity.
  • Increased connective tissue elasticity.

Non-thermal effects:

  • Mechanical: increase cellular diffusion, membrane permeability, collagen synthesis and break down of soft tissue adhesions.
  • Acoustic streaming: physical forces of the sound waves that provide a driving force capable of
    displacing ions and small molecules.
  • Mechanical pressure applied by the wave produces unidirectional movement of fluid along and around
    cell membranes.
  • Chemical increase in enzyme activity, ATP activity, cell membrane permeability, and tissue repair.


Goals for electrotherapy treatment include:

  • Pain relief.
  • Decreased edema (swelling).
  • Decrease muscle spasm.
  • Increased tissue healing and circulation.
  • Muscle reeducation.
  • Increased range of motion.

Electrotherapy modalities such as Interferential Current have many physiological effects.

  • Thermal effect: Heat is developed in all forms of currents.
  • Chemical effects: Leads to ionic changes in tissues
  • Kinetic effects: Therapeutic muscle stimulation to produce contraction.
  • Excitable tissues: Nerves, muscles and glands.

Systemic level

  • Analgesic effect (endorphins, enkephalins, dopamines, dymorphins).
  • Modulation of visceral activity.

Segmental level

  • Muscle group contraction with effects on joint mobility, synergistic muscle activity.
  • Muscle pumping action affects macrocirculation.
  • Changes in macrocirculation not associated with skeletal muscle contraction.

Tissue level

  • Skeletal muscle contractions leads to changes in speed, strength, reaction time and fatigability.
  • Smooth muscle contraction/relaxation yields changes in blood flow.
  • Tissue regeneration and remodeling.

Cellular level

  • Excitation of peripheral nerves.
  • Changes of membrane permeability of non-excitatory cells.
  • Alterations in cellular metabolism.
  • Alterations in microcirculation.