Quantitative investigations on newly-built bone and defects. Its time-dependent changes of morphological and
Abstract:
Bone growth in drillholes in sheep tibiae were examined morphologically and biomechanically after 4, 6, 9, and 12 weeks. Selected bone specimens were removed from the defective areas and used to determine the strength and, with the aid of microradiographs, the volume of new bone. Strength as well as volume of new bone increased in the defects within the healing time. However, the strength of the newly-formed bone reached only 20% of the strength of normal cortical bone. This is caused by the random structure of new bone which, despite the repair of the defect and the nearly normal mineralization, is not yet adapted to the adjacent normal cortical bone.
Related Concept Videos
Bone Remodeling
Bone remodeling is a continuous and balanced process of bone resorption by osteoclasts and bone formation by osteoblasts. In adults, it helps maintain bone mass and calcium homeostasis. While mechanical stress can stimulate turnover as part of the normal maintenance and reparative process, several hormones also regulate bone remodeling.
Bone Remodeling and Repair
Osteoclasts are cells responsible for bone resorption and remodeling. They originate from hematopoietic progenitor cells present in the bone marrow. Numerous progenitor cells fuse to form multinucleated cells, each with 10-20 nuclei. A single osteoclast has a diameter of 150 to 200 µM. These cells have ruffled borders that break down the underlying bone tissue and release minerals such as calcium into the blood in bone resorption. Osteoclasts cling to bones with their ruffled edges during bone...


