According to the American Academy of Orthopedic Surgeons, there are over 200,000 hip replacements performed each year in the United States. The most common reason for hip replacement is osteoarthritis, the most common form of arthritis. “Hip School,” an exercise program for patients with osteoarthritis and hip replacement was developed in Germany in 1995 by orthopedic surgeon Thomas Horstmann and physiotherapist Georg Haupt.