Bone is metabolically active
throughout life. The remodelling of bone requires the
sequential and coordinated actions of the osteoclasts, to remove
bone (resorption), and the osteblasts to replace
it. After skeletal growth is complete, remodelling of bone
continues and results in an annual turnover of about 10% of the
adult skeleton.
A change in the balance
between bone resorption and bone formation ultimately results in a
net loss or gain of bone tissue. High bone turnover, with increased
bone resorption, can compromise bone strength, leading to a
thinning of the bone structure, resulting in abnormal bone
microarchitecture and reduced bone mineralization. This, in turn,
leads to a greater propensity to fracture.
An increased level of bone
resorption is the primary cause of age-related bone loss often
resulting in osteopenia and is the major cause of osteoporosis.