Dynamic Roentgen stereophotogrammetry Dynamic Roentgen stereophotogrammetry Dynamic Roentgen stereophotogrammetry (also referred to as dynamic RSA) is a modern and sophisticated x-ray recording method, used to measure real-time 3D motions of prostheses and bones during motion with high accuracy. It is mostly used in orthopedic research settings and is an advancement of conventional RSA. Conventional static RSA is used to evaluate migration of prosthesis with respect to the bone in three dimensions as a function of time. Migration of the prosthesis are normal 12‐24 months after the surgery. Ongoing migration increase the risk of aseptic loosening with revision surgery as a consequence. The method
Multiple discovery Multiple discovery The concept of multiple discovery (also known as simultaneous invention) is the hypothesis that most scientific discoveries and inventions are made independently and more or less simultaneously by multiple scientists and inventors. The concept of multiple discovery opposes a traditional view—the "heroic theory" of invention and discovery. When Nobel laureates are announced annually—especially in physics, chemistry, physiology, medicine, and economics—increasingly, in the given field, rather than just a single laureate, there are two, or the maximally permissible three, who often have independently made the same discovery. Historians and sociologists have remarked on the occurrence, in science, of "multiple