Chapter 16. Diathermy

What Is Diathermy? • Prefix dia = • Suffix therm = • High-frequency ______that is primarily used to generate heat into body tissues • Involves ______and ______of EM by the body • Heat is produced by the ______of tissue to the passage of energy.

Why Is Diathermy Not Often Used in Sports Medicine? • – Shortwave diathermy units range from $5,000 to $25,000, making them prohibitive for many situations. • Poor information – Many of the contraindications regarding diathermy use are based on speculation. • Lack of research – Diathermy studies performed before 1970 were done on equipment that was not of caliber.

Classifications of Diathermy • Surgical – • Medical – Three types •  1 MHz, or 300 m  Oldest method  Not used anymore •  27.12 MHz, or 11 m  Wave identical to a shortwave radio  Most common type used in sports medicine •  2450 MHz, or 12 m  Similar to radar  Seldom used in United States  More contraindications than shortwave Shortwave Diathermy (SWD) • Shortwave diathermy device is basically a • Components • Generator:

• Drum:

• Three frequencies • • •

How Does SWD Work? • As the radio frequency exits the drum, an oscillating magnetic field is produced in the body. • As the magnetic field passes through the tissues, it causes reactions in the tissues.

Applicators or Drums • Most common type of SWD applicator is the induction drum electrode • Drum electrode is made up of

Shortwave (SWD) vs. Microwave (MWD) – – 2456 and 915 MHz

– Heating mainly owing to magnetic – Heating mainly owing to fields

– Penetrates – If fat is <0.5cm; MWD can go 5 cm deep. – At >0.5 cm penetration, temperature is ______of SWD

– Can apply directly to skin – Spacing required

– Doesn’t heat up metal as much as – No metal MWD – Most commonly used in sports – medicine

SWD Device • Shortwave units can either be one-drum or two-drum setup. • A one-applicator unit is called a • A two-applicator unit is called a • Inside the applicator drum is a single copper electrode (with high ______) shaped into a coil.

How Does Diathermy Work? • Runs on 110 V electricity from a wall outlet • Generator converts ______electricity to ______frequency, which is usually ______MHz. • ______frequency then passes through an inductive applicator (______). • As the high-frequency electrical energy is applied to the ______, a fluctuating ______field is generated around the ______. • As the ______frequency exits the ______, an oscillating ______field is produced in the body. • As the ______field passes through the tissues, it causes reactions in tissues, producing both ______and ______effects.

Two Ways in Which Diathermy Heats Tissues • (1) • Molecule whose ends carry opposite charges. • The ______wave produced by SWD causes rotation of dipoles • As these rotation, ______occurs, resulting in ______

• (2) • A ______field generates small ______fields. • Fields ______and increase cell ______, which causes ______• When a body part is placed within the ______field, electrical currents are induced within that conductor (tissue). • Within the body part, small eddy currents move in the direction of the ______field. • Rotation, movement, and vibration of ______in the tissues result in heat. • Greatest eddy current activity occurs in tissues high in ______(blood and muscle).

Energy Distribution and Heating Effects on Various Tissues Via SWD

Types of Diathermy • Continuous • • • Pulsed • • Physiological Effects of SWD • Increase blood flow, up to 30 mL/g of tissue – Comparable to • Increased • Decreased • Decreased • Increased ______cell infiltration • Realignment of ______and collagen content to increase ______• ______activity • Collagen deposition • New capillary growth • •

SWD: Indications • Strains • Sprains • Contusions • Tendinosis • Bursitis • Pain • Resolution of inflammatory infiltrates and exudates • Joint stiffness • Osteoarthritis • Decreased ROM • Increase extensibility of collagen fibers

SWD: Contraindications • More contraindications with Diathermy than any other modality • So why not just use ultrasound instead? • When tissue temperature rise is not indicated • Ischemic areas • Anesthetic areas • Effusion • Eyes (or contact lens) • Testes, ovaries • Caution over pelvis during pregnancy • Over moist wound dressings • Fever • Epiphysis • Cancer • Pacemakers • Metal implants (pins, screws)

Typical Diathermy Control Panel

1. Press power button on. 2. Select mode. 3. Press treatment button on. 4. Unit will turn off in 20 min, unless clinician adjusts time.

Application Procedures for Diathermy • Obtain history (condition, contraindications). • • • If indicated, drape with toweling. • Place electrode drum on treatment area. • • Set pulse duration (μsec). • Set pulse frequency (pps). • Adjust intensity. • Set treatment time (15–30 min). • • • When timer shuts off, terminate treatment. • Assess treatment efficacy. • Record treatment parameters. Thermal Ultrasound vs. SWD • Can heat tissues ____–___ cm deep • Can heat tissues ____–___ cm deep to >40°C to >40°C

• Heats ______areas • Heats ______areas

• Short stretch/thermal window • Long stretch/thermal window – –

• Edema reduction of small areas and • Decrease acute inflammation and joints edema of

• Stimulate • Stimulate tissue healing of

• Tigger point acute • Decrease pain in

• Acoustic • Magnetic • Stable

• • – Cell membrane permeability – Cell membrane permeability owing to mechanical effect on cell owing to electrical effect on cell Ca+ Ca+ gating gating

A few contraindications A few more contraindications Couplant required No Possible disrobing Can be applied over most clothing Easy to use Less affordable Monitoring by clinician Heats small areas Retains heat Retains heat _____ to _____ times longer