Cartilage differs from bone in that, the cartilage can increase in size by

The interstitial growth or expansion capability of cartilage, even under pressure leading to its avascularity, precluding ischemia, (cartilage nutrition is provided by perfusing tissue fluids that are not easily obstructed by load pressures), allows for directed prototype cartilage growth. The cartilage template is then replaced by endochondral bone, accounting for indirect bone growth. Intramembranous bone growth, by contrast, is by direct apposition of osseous tissue in osteogenic (periosteal) membranes creating accretional growth, often with great speed, especially over rapidly growing areas, such as the frontal lobes of the brain, or at fracture sites. Ref: Textbook of orthodontics 2nd ed Gurkeerat Singh page no 13