The physis is the growth plate near the end of bones, from which the new bone cells develop.
Growth plate fusion
The growth plates fuse in adulthood. Any interference with the growth plates prior to fusion may result in growth anomalies of the limb.
Regenerative Medicine Approaches for the Treatment of Pediatric Physeal Injuries. Shaw N, Erickson C, Bryant SJ, Ferguson VL, Krebs MD, Hadley-Miller N and Payne KA. Tissue Eng Part B Rev. 2018 Apr 1; 24(2): 85–97.