This is a fracture of the lower end of the radius bone near the wrist and is typically caused by a fall onto an outstretched hand during a fall. So it is a break in the radius bone close to the wrist. We also see this fracture in high-impact accident cases, particularly motorcycle accidents where the cyclist lays down the bike. You know pretty quickly if you likely have a Colles fracture even before an x-ray because of the bump it causes on the top of the wrist.