Osteoporosis is a bone-thinning condition that mainly occurs during later life in humans. As we age, our bone-generating cells — the osteoblasts — work more slowly. The result is an imbalance between bone building and degeneration and a reduction in bone strength. The outer, compact bone ‘shell’ thins, the number of struts that make up the inner, spongy bone reduce in number and the bone gets brittle. For around 3 million people in the UK this process is unusually fast and as a result they suffer from osteoporosis (= porous bone). Even a fall from standing height can cause the fragility fractures from which osteoporosis patients typically suffer. Once a bone is fractured, healing efficiency and speed are greatly reduced in osteoporosis patients.
Osteoporosis particularly affects women after menopause, when blood oestrogen concentrations drop. Oestradiol, the primary oestrogen in humans, prevents bone degeneration by suppressing the enzyme caspase-3. This enzyme normally promotes apoptosis — programmed cell death — in osteoblasts. For some osteoporosis patients, the anti-cancer drug Raloxifene, which also makes osteoblasts more sensitive to oestrogen, is a treatment option (see also BIOLOGICAL SCIENCES REVIEW, Vol. 28, No. 3, pp. 15–19). Another therapy — low magnitude, high frequency vibration (LMHFV) — has shown some positive effects on bone healing and strengthening. LMHFV involves regular bouts of mild, whole body vibration at specific frequencies.
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