Assessment of the 2D:4D ratio in aggression-related injuries in children attending a paediatric emergency department.
BACKGROUND
The 2D:4D ratio is a sexually dimorphic trait. A lower ratio is correlated with sporting prowess, successful financial trading, risk taking behaviour, aggression, and aggression-related injuries, such as the fifth metacarpal fractures.


OBJECTIVE
We aimed to assess if the ratio correlates to skeletally immature patient aggression.


METHODS
Radiology reports were searched for the terms "5th metacarpal" or "boxer". Of 537 X-rays, 142 had fractures. The mechanism of injury was recorded in 102 patients, differentiating aggressive and non-aggressive injury groups. Bone age and chronological age were recorded.


RESULTS
A clear male preponderance for aggression was identified with only 60% of non-aggressive injuries occurring in males compared to 95% in the aggression group (p < 0.001). Patients with aggression injuries were older chronologically (14.6 vs 12.7, p < 0.001) and by bone age (14.5 vs 13.0, p < 0.001). For male patients, there was no difference in the 2D:4D ratio (p = 0.94); however, for females, the difference was significant (p = 0.04).


CONCLUSIONS
Aggression injuries occur at an older age and are more common in males. In the female cohort, there was a distinct difference in digit ratio.
Children's University Hospital, Temple Street, Dublin 1, Ireland.
D E
DE
O'Briain
Children's University Hospital, Temple Street, Dublin 1, Ireland. peterhughdawson@gmail.com.
P H
PH
Dawson
Children's University Hospital, Temple Street, Dublin 1, Ireland.
J C
JC
Kelly
Children's University Hospital, Temple Street, Dublin 1, Ireland.
P
P
Connolly
D000293:Adolescent; D000374:Aggression; D002648:Child; D004636:Emergency Service, Hospital; D005260:Female; D005383:Finger Injuries / Q000453:epidemiology*; D050723:Fractures, Bone / Q000453:epidemiology*; D006801:Humans; D008297:Male; D011859:Radiography; D012189:Retrospective Studies; D012737:Sex Factors
Aggression; Boxer’s fracture; Digit ratio; Fracture; Hand