BIOMECHANICAL FACTORS IN PATIENT SELECTION FOR RADIOGRAPHY AFTER HEAD-INJURY

In order to assess the predictive value of certain biomechanical param eters for skull fracture after head injury, a prospective analysis was undertaken of a series of 5416 head-injured patients. In each case an assessment was made at presentation as to the velocity of impact and the physical properties of the impacting agent. The incidence of skull vault fracture was then calculated for injuries sustained at differen t velocities and for different types of contact. The incidence of frac ture was also calculated with respect to the presence of post-traumati c amnesia (PTA). The incidences (95 per cent confidence intervals) of skull fracture at low, medium and high speeds were 0. 1 7 (0.042 7-0.4 33), 1.99 (1.47-2.63) and 10.2 (7.41-12.6) per cent respectively. Frac tures tended to occur with greater frequency after impacts against bro ad hard surfaces or small objects rather than against broad soft objec ts. The percentage incidence of fracture in adults suffering more than 5 min of PTA was 17.93 (12.4-23.5) compared with 0.6 74 (0.3 72-1. 1) in those without amnesia. Patient selection for skull radiography aft er an apparently minor head injury can be guided by an assessment of p ost-traumatic amnesia and the biomechanics of the injury.