Final answer:
A Colles fracture is a type of break at the distal end of the radius where the smaller fragment is displaced posteriorly, often causing a 'dinner fork' deformity of the forearm.
Step-by-step explanation:
A fracture at the distal end of the radius in which the smaller fragment is displaced posteriorly is called a Colles fracture. This type of fracture results in a transverse break across the distal radius, with the distal fragment being displaced posteriorly and superiorly. The displacement causes a visible deformity, often referred to as a "dinner fork" appearance of the forearm just above the wrist. Colles fractures are particularly common in older individuals, especially those with osteoporosis, and occur most frequently when a person tries to break a fall with an outstretched hand, which is often seen in activities such as snowboarding or skating. Surgery may be necessary if the fracture is unstable, in which case metal plates and screws could be used to stabilize the bone and facilitate proper healing.