Pinned leg fracture. Coloured X-ray of a metal plate and screws (yellow) in the lower left leg of a female patient who has fractured her tibia (shin bone). At top left is the knee and at bottom right is the ankle. The thinner bone at right of the tibia is the fibula. Such fractures are usually caused by severe force, such as a fall or a car accident. The plate was surgically screwed to the tibia in order to immobilise the bone once the fractured ends had been realigned and to make sure that the break fuses properly. In an adult a weight-bearing bone such as the tibia may take up to six months to knit together completely.