The use of cold and heat during the process of rehabilitation is a very common practice due to the benefit of these physical agents and due to their ease of accessibility for continued use by the patient at home.
Cryotherapy involves the use of cold as a therapeutic medium and makes use of its pain-killing and anti-inflammatory properties.
Thermal therapy involves the use of heat as a therapeutic medium and employs its pain-killing, calming and soothing properties.
There are different forms and standards of application depending on the desired outcome. Your physiotherapist is the professional best qualified to advise you concerning its use.