The Interpretation of Injuries in Road Accidents

C. KEITH SIMPSON

Reader in Forensic Medicine, Guy's Hospital Medical School, University of London, England.

(Th is refiort i s based on a tape recording of Dr. Simpson's remarks. T h e lecture was @rofusely illustrated with colour slides).

Dr. Simpson first said that the same serious-minded approach should be made to the investigation of cases of grievous bodily harm and death when the cause was a motor vehicle, as when it was any other kind of blunt instrument. In particular, he felt that it should be a more common practice for coroners to visit the scenes of road accidents. In the U.S.A. the Medical Examiner system, which combined the roles of coroner and pathologist in one individual, en- couraged that individual to make such visits.

Both barristers and pathologists also tended to take a less serious view of killing by motor vehicle than of other forms of homicide, and this he deplored. In the case of the pathologist, it was not enough in conducting an autopsy simply to determine the cause of death. He should also attempt to relate the injuries found to the supposed circumstances of the accident, so that he could refute or corroborate the circumstantial evidence in the case, and the state- ments of witnesses, who were often very interested parties in the outcome.

While the pathologist rarely saw the scene of an accident, he should see the clothing on the body and scrutinise it for foreign matter which might throw important light on the sequence of events at the time.

Turning to characteristic marks on bodies, Dr. Simpson then showed illus- trations of two cases where the recognition of radiator grille and tyre marks had shown the evidence of the two drivers involved to be untrue.

A number of illustrations of the types of injury to pedestrians, cyclists and motor cyclists resulting from impact with vehicles, were then discussed. As well as the bumper bar, there were a number of other projections on the front of cars such as headlamp hoods, mascots and driving mirrors which could cause injuries, and underneath a car there were also projections which could trap, and possibly carry away, both clothing and tissue.

When frontal impact with a pedestrian occurred, the first injuries were a t about knee or hip level in the case of private cars. With larger vehicles such as lorries, the first impact might be as high up on the body as the head, however.

Secondary injuries could be caused by a further impact either with the ground or the vehicle. In the former case, these generally occurred on knee, hip, hand and side of the face, and they could be in the same place as the injuries due to the first impact. When the secondary injuries were caused by another impact with the vehicle, it was because the first impact had occurred below the victim's centre of gravity, causing his body to be lifted and flung against the vehicle. The exact outcome would depend on the particular factors in each case. Sometimes there might be no further injury, but in other cases it might be very difficult to distinguish the secondary from the initial injuries. Those due to impact with the windscreen pillar were not necessarily easily recognised, and modern toughened glass tended to shatter rather than to cut. Black eyes could result from fractures in the bony socket of the eye and not

only from a blow on the eye itself. Falls on to a coarse stony ground could cause injuries which at first sight might appear to be due to an assault.

Pedestrians were frequently injured by walking into the side of vehicles and the impact might even be of sufficient force to detach part of the vehicle such as a car door handle. At Guy's Hospital Medical School, all victims of road accidents, whether living or dead, were examined for blood and urine alcohol. The value of this practice was shown when a certain pedestrian was killed in this type of accident. He was said to be a strict teetotaler, but was found to have the equivalent of three-quarters of a bottle of gin in his body.

Motor cyclists, when falling after an impact, commonly become entangled with their vehicles, causing complicated injuries. Some deep injuries could be caused by protruding parts digging into the body, and these might be characteristic. Cyclists who were about to turn when struck, might be hit first in the back and subsequently suffer further injuries by being caught up and torn by the vehicle. Such injuries were often impossible to interpret except in a very general way.

The practice of mortuary assistants in cleaning up bodies and removing clothing before the body was examined by a pathologist was unfortunate and might cover up vital evidence, especially in hit-and-run accidents.

Next, Dr. Simpson mentioned some general characteristics of the injuries due to road accidents. Where a body was crushed and ground, the skin on the under surface became heated. I t might then blacken and dry in a few hours. Such grazes were then of quite different colour from ordinary skin grazes and could assist in deciding which way the body had slid. Pinning by the chest impeded the return flow of blood above this level in the body, which rapidly became discoloured. This discolouration could occur from pinning lasting only a minute or two.

The interpretation of injuries was a duty of the pathologist. I t should be done in writing and in such a way that it was useful to the police and the coroner. The injuries should preferably be photographed to scale and the inferences drawn from the injuries should be checked against what was known about the accident from other sources.

Finally, Dr. Simpson asserted that a pathologist should never say anything about the speed of a vehicle which had caused the injuries. This was because he did not know the speed and direction of travel of the injured person, or his stance at the moment of impact.

D.P.