Ultrasound: to heat or not to heat—that is the question

This paper reviews aspects of ultrasound that impact on planning and methods of treatment, including biophysical aspects, interactions between ultrasound and tissues and the literature pertaining to efficacy of ultrasound. The number of properly controlled clinical studies is limited. The literature is difficult to interpret because there are differences among studies related to intensity and duration of treatment. Clinical protocols for heating superficial and deep tissues can be derived from the research involving thermal ultrasound. There is still uncertainty regarding optimum protocols for promoting tissue repair. Efficacy of ultrasound in different clinical conditions still needs to be addressed.