Dear Yanny

Bone remodeling is a continuous process of bone resorption and formation for the purpose of maintaining normal bone mass. Normal bone mass indicates healthy bones that are strong and free from problems like osteoporosis. This process goes on inside the human body as long as the person is living. Cells that play important roles in it are osteoclasts, which are responsible for bone resorption; osteoblasts, which are vital in the formation of bones; and osteocytes, which send the signals that bones are being exposed to stress or injury.

Constant remodeling allows bones to perform their many functions, including structural support to the whole body and important storage sites of calcium. With bone remodeling, the body is also able to repair small bone fractures that occur from daily physical activities. Old bone is being replaced by new bone during the remodeling cycle. In adults, this occurs at a rate of about 10% each year. This is a natural process to ensure maintenance of normal bone mass as a person ages.

The remodeling cycle usually starts when injury or mechanical stresses occur in bones. Growth hormones stimulate the production of osteoclasts, which then release enzymes capable of dissolving the bone matrix, creating pits in most bone surfaces. Their lifespan is approximately two weeks, and then they die naturally through a programmed process of cell death, or apoptosis.

There is not a specific time for remodeling but in cancellous bone is faster than cortical bone

Remodelling is a continuous process. From clot to collagen to woven to matured bone in case of a defect / gap / fracture / surgery. Matured bone remodels continuously. The failure to remodel or a defective remodeling is the basis of certain pathologies.

There are at least three phases of normal bone remodelling. Primary mineralization takes place in about 5-10d. Secondary mineralization in about 130d in trabecular bone. And the tertiary phase is the slowest, taking place via bone fluids and slowed down if by immobility (details given in a 2009 paper of mine).

Dr. Yanny, I think this question needs to be clarified. Do you mean remodelling after fracture ? You mention "after implantation". What kind of implantation ? Bone grafting for fracture non-union or for filling of a bone defect ? If the latter is the case, then the process of "remodelling" would depend on what kind of grafts were used - allogenous or autogenous, cancellous or cortical, freshly frozen or lyophilized, demineralized or mineral containing ?

3 - 6 months.