| pg < 0.001 | Age groups | ||||
| Under 6 years (n = 243) | 6 - 9 years (n = 259) | 10 - 12 years (n = 250) | 13 years and more (n = 174) | p value | |
| Fall | 65.8% | 52.9% | 46.4% | 39.7% | pt < 0.001 |
| Contact | 21.8% | 25.9% | 26.8% | 21.8% | p = 1.000 |
| Movement | 4.5% | 13.5% | 19.2% | 20.1% | pt < 0.001 |
| Other mechanism | 7.8% | 7.7% | 7.6% | 18.4% | p < 0.001 |