The growth plate
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A-P xray of young child's wrist with growth plates marked by arrows
A-P xray of young child's wrist with growth plates marked by arrows
Microscopy of growth plate.  Growth progresses from the epiphyseal to the metaphyseal side.  Cartilage cells develop, hypertrophy and then transform into bone cells. (Source of image  unknown)
Microscopy of growth plate. Growth progresses from the epiphyseal to the metaphyseal side. Cartilage cells develop, hypertrophy and then transform into bone cells. (Source of image unknown)

Growth plates (orange arrows pointing towards; also known as "physes") are found at the end of long bones in growing children. A layered pattern of cartilage (on the epiphyseal side) is gradually transformed into new bone exiting at the metaphyseal side of the physis.

Injury may disturb this process and create abnormalities of growth. The consequences of this depend on the degree of injury (all or part of the growth plate), the location (medial, central, lateral) and the growth potential of the child (defined by radiographic means as a "skeletal age"). Salter and Harris have classified these injuries. The most common physeal fracture is a Salter II injury (below) with a triangular metaphyseal fragment and no involvement of the epiphysis. Lower grade Salter-Harris fractures (I, II) rarely result in growth disturbance while higher grade injuries (III, IV, V) frequently do.

The Salter-Harris classification of growth plate injuries.
The Salter-Harris classification of growth plate injuries.
Salter II fracture of thumb proximal phalanx.  This has a low probability of growth disturbance.
Salter II fracture of thumb proximal phalanx. This has a low probability of growth disturbance.