ANATOMY

Detailed explanation-1: -The regulation of bone remodeling is both systemic and local. The major systemic regulators include parathyroid hormone (PTH), calcitriol, and other hormones such as growth hormone, glucocorticoids, thyroid hormones, and sex hormones.

Detailed explanation-2: -Bone remodeling is the result of two opposite activities, the production of new bone matrix by osteoblasts and the destruction of old bone by osteoclasts.

Detailed explanation-3: -Bone remodelling relies on the correct function of two principal cells of the bone tissue: the osteoclasts, multinucleated cells that destroy the bone matrix, and the osteoblasts, having osteogenic functions.

Detailed explanation-4: -Bone remodeling takes place in what Frost termed the Basic Multicellular Unit (BMU), which comprises the osteoclasts, osteoblasts, and osteocytes within the bone-remodeling cavity (Fig. 1). In cancellous bone remodeling occurs on the surface of trabeculae and lasts about 200 days in normal bone.