Physis

The physes (singular: physis) or growth plates are found in bones that undergo endochondral ossification.

Radiographic features

The physis appears as a radiolucent line in skeletally-immature patients located between the metaphysis and epiphysis.  It contains zones of mesenchymal cells in various maturation stages (see physeal anatomy illustration).

As the metaphysis and epiphysis mature and fuse, the physis thins, disappears, and endochondral ossification ceases.  A subchondral bone plate forms with horizontally-oriented trabeculae which appears as a radiopaque transverse fusion line (physeal scar).

History and etymology

From the Greek word phýsis for nature and phŷlon meaning race .

Related pathology

Congenital

• osteochondrodysplasia

Trauma

• Salter-Harris fractures 

Metabolic

• rickets: failure of calcification leads to accumulation of cells in the hypertropic cell zone (maturation zone)
• growth recovery lines
• hypophasphatasia

Differential diagnosis

• stress fracture

See also

• diaphysis
• metaphysis
• epiphysis
• apophysis