Research into risk factors for fracture have found that children who have narrower bones and lower bone mass are more likely to fracture than those with larger bones. Increased bone mass following whole body vibration has been demonstrated in postmenopausal women, young women with low bone mass and children with disabling conditions such as cerebral palsy. However little is known of the acute bone response to WBV in healthy children.
This thesis will determine the range and rate of the acute bone response to WBV in apparently healthy boys and in boys with a history of fracture. Boys were randomised to 10 minutes of WBV on 1, 3, or 5 consecutive days delivered by the Juvent 1000 (low magnitude, high frequency), Galileo Med M (high magnitude, high frequency) platforms or control. Fasted blood samples were collected pre- and post-vibration, on day 8 (and day 12 in the fracture cohort only) for markers of bone turnover, OPG and sclerostin.
P1NP and CTX increased from baseline to day 8 in the boys with no prior fracture by 25.1% and 10.9% respectively, but not in those who have a history of fracture. At day 12 the boys with a history of fracture demonstrated a non-significant decrease in CTX of 5%. No change was observed in either group in sclerostin, with a trend towards an increase in OPG in the boys with no prior fracture only at day 8.
This is a novel finding showing that apparently healthy pre-pubertal boys with a history of fracture do not respond to loading in the same way as those who have not fractured. If reduced responsiveness is present prior to fracture and is related to reduced bone accrual, this could to some extent explain increased fracture susceptibility in some children.
