Ultrasound is quickly becoming the technique of choice in the measurement of bone density. Proving cheaper and more portable than previous techniques, and also having the advantage of not using ionizing radiation, it is likely that the use of various ultrasound systems will become increasingly widespread in clinical practice. This book is a comprehensive review of the systems currently available, preceded by a summary of the basic science of ultrasound and concluding with a section on clinical studies, trials and experience in a number of countries. Likely future developments are also discussed, bringing the book completely up to date.