Impact of growth plate senescence on catch-up growth and epiphyseal fusion.

In mammals, longitudinal bone growth occurs rapidly in prenatal and early postnatal life, but then slows and eventually ceases. This deceleration, which reflects a decline in chondrocyte proliferation, was previously attributed to a hormonal or other systemic mechanism. However, new evidence suggests that it is due to a local mechanism within the growth plate. In particular, recent findings suggest that growth plate chondrocytes have a finite proliferative capacity that is gradually exhausted, causing growth to slow and finally stop. This concept has provided insight into clinical phenomena including catch-up growth after transient growth inhibition, catch-down growth after transient estrogen exposure, and epiphyseal fusion.