The biology of fracture repair.

Fracture healing or bone regeneration has been described histologically, histochemically, biochemically, physiologically, biophysically, and biomechanically. However, these various descriptive analyses do not answer the following all-important questions: What is the inductor(s) that incites cells to start forming bone at the fracture site? What are the responding cells that serve as progenitor cells for the osteoblasts and chondroblasts that appear in the interfragmentary gap? Do factors exist that are required to maintain the regenerating process to its conclusion? Until answers to these questions are found in the laboratory, we will not know "how" bone heals or regenerates itself.