Matrix metalloproteinases (MMPs), responsible
for extracellular matrix remodelling and angiogenesis, might play
a major role in the response of the growth plate to detrimental
loads that lead to overuse injuries in young athletes. In order
to test this hypothesis, human growth plate chondrocytes were subjected
to mechanical forces equal to either physiological loads, near detrimental
or detrimental loads for two hours. In addition, these cells were
exposed to physiological loads for up to 24 hours. Changes in the
expression of MMPs -2, -3 and -13 were investigated. We found that expression of MMPs in cultured human growth plate
chondrocytes increases in a linear manner with increased duration
and intensity of loading. We also showed for the first time that
physiological loads have the same effect on growth plate chondrocytes
over a long period of time as detrimental loads applied for a short
period. These findings confirm the involvement of MMPs in overuse injuries
in children. We suggest that training programmes for immature athletes
should be reconsidered in order to avoid detrimental stresses and
over-expression of MMPs in the growth plate, and especially to avoid
physiological loads becoming detrimental. Cite this article:
Obesity is thought to be an aetiological factor for slipped capital femoral epiphysis (SCFE). We analysed changes in the incidence of SCFE in Scotland over the last two decades. During this period rates of childhood obesity have risen substantially and evidence for a relationship between these changes and the incidence of SCFE was sought. We found that the incidence of SCFE increased from 3.78 per 100 000 children in 1981 to 9.66 per 100 000 in 2000 (R2 = 0.715): a two and a half times increase over two decades. It was seen at a younger age, with a fall in the mean age at diagnosis from 13.4 to 12.6 years for boys (p = 0.007) and 12.2 to 11.6 for girls (p = 0.047). More children under eight years old were seen with SCFE in Scotland in the decade to 2000 than in the previous decade (p = 0.002, R2 = 0.346). A close correlation was observed between rising childhood obesity over the last 20 years in Scotland and an increasing incidence of SCFE.
