1st yr pg in orthopaedics
Diathermy is a therapeutic treatment commonly
prescribed for muscular and joint associated pains.
The term ‘diathermy’ means ‘through heating’ or
producing deep heating directly in the tissues of the body.
• ‘ Dia’ through (also means two)
• ‘thermy’ heat or temperature
It simulates the circulation, relieve pain, enhances rate of
recovery of healing the tissue.
PRINCIPLE OF DIATHERMY
1.Before injury, the dipole molecules of the
body tissue are arranged on the basis of
2.When the tissue is damaged the dipoles
distribution become irregular and deviates
from polarity based arrangement .
3.Under the influence of an electric field , they
rotate according to the polarity of their
charge in the direction of the field lines and
get rearranged and tends to acquire its
previous stage of polarity
CHALLENGES OF DIATHERMY
1.As the subcutaneous layer is fatty , direct
delivery of heat to the deep layers of tissue is
2.Diathermy involves uneven and uncontrolled
delivery of heat therefore sometimes instead
of the target tissue , surrounding tissue gets
• Diathermy uses an electric current to produce
heat deep inside a targeted tissue.
• It can reach areas as deep as two inches from
the skin’s surface.
• The diathermy machine does not apply heat
directly to the body.
• Instead, the current from the machine allows
the body to generate heat from within the
• As the heat increases, it promotes blood flow.
• It can also help improve flexibility in stiff joints
and connective tissue.
BENEFITS OF DIATHERMY
Intense heat delivered provides pain relief
and better flexibility
TYPES OF DIATHERMY
1. SHORT WAVE DIATHERMY
2. LONGWAVE DIATHERMY
3. MICROWAVE DIATHERMY
4. ULTRASOUND DIATHERMY
5. LASER DIATHERMY
SHORT WAVE DIATHERMY
Def.: SWD is a modality that produces deep
heating via conversion of electromagnetic
energy to thermal energy.
• The pattern of heat produced depend on:
• ᴥFreq. used.
• ᴥ type of SWD unit.
• ᴥwater content of the tissues.
Shortwave diathermy current freq. 10 – 100
• (The shortest radiofrequency wave is used in therapeutic diathermy.)
• the commonly used in medical work having
freq. of 27.12 MHz with wavelength of 11
ether continuous or pulsed (PSWD).
o PSWD: application of series of short pulses of
SWD so that short periods of SWD interrupted
by gaps where there is no SWD.
o The pt. receives lower dose of SWD energy if
compared with continuous SWD applied of the
o The tissues will receive lower thermal load.
• SWD: produce both deep and sup. Tissue
heating, under certain controlled conditions
• it’s applied for 20 min at the max tolerable
Types of Shortwave Diathermy
• Induction Field
• Capacitive Field
Induction Field Diathermy
• Places the patient in the
• Current flowing within the
coil produces a rotating
• Magnetic field produces
eddy currents in the tissues
• Eddy currents cause friction
that produce heat
• Selectively heats muscle
• Also referred to as:
• – Magnetic field diathermy
Capacitive Field Diathermy
• Uses the patient’s tissues as a
part of the circuit
• The tissues’ electrical
resistance produces heat
• Selectively heats skin
– Muscle is heated via
conduction from the
• Also referred to as “condenser field
TYPES OF ELECTRODES
• Flexible pads:
consist of metal
in rubber and
• Space plates:
consist of a rigid
• a Perspex cover
• Coil or cable
of a wire with
plugs at either
• The monode :
flat, rigid coil
• The diplode :
of a flat coil
electrode encased in
a Perspex cover with
FACTORS INFLUENCE FIELD
DISTRIBUTION IN S.W.D
◉ Spacing :
•allows the lines of force in the electrostatic field to
diverge before entering the tissues. This prevents
concentration of heat in the superficial tissues and
ensures more heating through the part.
• Spacing provided by:
1. wrapping flexible pads in towel.
2. flat felt spacing pads
between pad electrode
3. air when using space plates.
• Normal spacing
even field distribution.
• Increased spacing deep
• Decreased spacing
• ◉ Electrode size:
•if the electrodes are too
small than the diameter of
treated part line of force
will be concentrated
• ◉ If the electrodes are
markedly larger the line of
force will be lost in the air.
• ◉ Ideally, the electrodes
should be slightly larger than
the area treated.
• To concentrate heat on one aspect of the part
the electrode should be unequal in size
(smaller one placed over the area where
concentration of heat is required).
• You can produce concentration of heat by
using equal size electrodes but with unequal
spacing (25 mm over concentrated area and
more than 30 mm on other electrode).
THERAPEUTIC VARIATION IN THE
Coplanar application to
structures on one aspect of
the body. If the spacing is less
than 25 mm more concentration
in the treat superficial tissue.
If spacing Increases more
.The distance between
adjacent ends must be
greater than the sum of skin
electrode distance (A+B)
otherwise the line of force
willpass directly between
Electrodes rather than tissues
• Two flexible pads,
two space plates or
flexible pad with
a space plate
• It is essential to put a
cotton towel between
the two limbs to any
• Cross-fire application:
For the treatment of
sinuses,space plates positioned after
half diagonally,of treatment time
the positions are alternate.
this ensures that the all the sinses
Care must be taken to avoid direct
placement over the eye
,uterinedisorders such as
• Application using a
• 1. The coil
• 2 Pancake
• Application using
• Adjust wings of
to the skin of the
The principal effect of SWD on the body is the
production of heat in the tissues due to the rise
1. Increased metabolism:
• Heating tissues accelerates chemical changes
such as metabolism, so oxygen and food stuffs
are used up.
• With increased metabolism, there will be
increased output of waste products.
Increased blood supply:
• As a result of increased output of waste products
such as metabolites, which act on the walls of the
capillaries and arterioles, these tissues dilate.
• In addition, heat has direct effect on blood
vessels, causing vasodilatation.
• Heat also produces stimulation of superficial
nerve endings, causing reflex dilatation of the
. General rise of temperature:
• As blood passes through the heated tissues, it
also becomes heated and carries the heat to
other body parts.
• Rise of temperature induces muscle relaxation
and increases the efficiency of muscle action.
. Fall in blood pressure:
• The generalized vasodilatation reduces the
peripheral resistance to blood flow.
• Heat also reduces blood viscosity, which helps
in the reduction of blood pressure.
. Increased activity of sweat glands:
• If a general rise of temperature occurs, there
will be increased activation of the sweat
• Effect on Inflammation
O2 and Nutritive
White blood cells
Assist in removal of Waste Products
All these effects bring about resolution of
. Effect on Bacterial Infection
• Inflammation is normal response of Body to bacteria
• Heating the tissue auguments these changes so
reinforces body's normal mechanism to of dealing
with infecting organisms
Ex. Boils, Carbuncles, Abscesses
. Reducing Healing time
• Increased Blood supply
• More Nutritive Material
• More O2 supply
. Relief of Pain
• Sedative Effect
• Removal of Waste Products
• Resolution of Inflammation
• Counter irritation
Effect on Muscle Tissue
• Muscle relaxation
• Relief of Muscle Spasm
• Musculoskeletal Disorders
Degenerative Joint Disorders
Ex. OA and RA
Muscle & tendon Tears
• Concentration of electric field
• Excess current
• Impaired blood flow
• Hypersensitive skin
• Leads touching skin
2. Electric shock
4. Precipitation of gangrene
• Metal implants or metal
jewelry (be aware of body
• Cardiac pacemakers
• Ischemic areas
• Peripheral vascular disease
• Perspiration and moist
dressings: The water collects
and concentrates the heat.
• Tendency to
• Sensory loss
• Deep X ray
• Unreliable patients
• Areas of particular sensitivity:
– Epiphyseal plates in children
– The genitals
– Sites of infection
– The abdomen with an
implanted intrauterine device
– The eyes and face
– Application through the skull