secondary healing (also known as indirect fracture healing) is the most common form of bone healing. it usually consists of only endochondral ossification. sometimes, intramembranous ossification occurs together with endochondral ossification. intramembranous ossification, mediated by perisoteal layer of bone, occurs without formation of callus. for endochondral ossification, deposition of bone only occurs after the mineralised cartilage this process of healing occurs when the fracture is treated conservatively using orthopaedic cast or immobilisation, external fixation, or internal fixation.