Although Doctors of Chiropractic focus primarily on the spine there are also special techniques used to adjust other areas of the body, such as the shoulder, ribs, elbows, wrists and hands, knees, ankles and feet. The more prominent Adjusting Techniques Taught at Chiropractic Colleges are Thompson, Gonstead, Diversified, SOT, Toggle Recoil, Logan and Activator. Dr. Thompson introduced the concept of adding motion by inventing a headpiece that would drop away as the adjustive thrust was applied to the vertebral segment. He was granted a patent in 1955 on his concept and thusly was born the Palmer-Thompson drop headpiece . Since the new idea was such a success Dr. Clay then went on to invent a table with drop pieces for adjusting the dorsal, lumbar and pelvic area.
Today there are numerous manufacturers of drop-piece tables used around the world.
The majority of the spinal adjusting utilizing the Thompson Technique has the patient lying prone. This is the basis for Dr. Clay's theory of proper spinal adjusting and the driving force that lead him to invent the drop table.