(22) 'Explosive' Exit Wound of front of Arm. Wound actual size eight days after its infliction. The prominences in the upper and lower parts correspond with the lacerated biceps. The dark crater led down to the fracture. In another week the wound had contracted to half the size. The entry aperture was a normal circular one. The arm a year later was used in the patient's employment as a hammer-man
With regard to the theories of the production of these phenomena, that of the transmission of a part of the force of the bullet to the comminuted fragments, which thus themselves acquire the characters of secondary projectiles, seems quite adequate.[18] Examination of any of the skiagrams in which considerable comminution has taken place, shows that the fragments are carried forward and perforate the tissues distal to the fracture.
Fig. 49.
'Explosive' Wounds of Legs. Large irregular entry (1 ×3/4 in.). First exit (2 in.) roughly circular. Second entry wound, produced by bone fragments driven out of left leg, very large and irregular (5 ×3½ in.). The measurements were taken eight days after infliction of the wounds. The right limb was amputated later for secondary hæmorrhage
Fig. 49, although a poor delineation of the actual condition, shows well the possible action of projected fragments, even after they have been driven from the wound. In this case either a large or a ricochet bullet entered on the outer aspect of the upper third of the left tibia; it produced a severe comminuted fracture, the fragments from which, together with the deformed bullet, then struck and perforated the upper third of the right tibia. A large irregular entry wound 5 inches in transverse diameter was produced in the second limb together with a comminuted fracture of the bone. The right limb had eventually to be amputated for secondary hæmorrhage, but I am unacquainted with the later history of the patient.
The mode of displacement of the lateral fragments when a wide shaft such as that of the femur is struck, throws some light on that of the displacement of soft tissues such as the component parts of a perforated nerve or artery. The bullet, passing through, expends the chief part of its energy in driving before it the fragments produced in its direct course, while a minor part of the energy is expended on displacing the lateral fragments, which are pushed to either side without becoming separated from their periosteal attachment. The appearance, in fact, somewhat suggests what might be expected were a small charge of dynamite introduced into the centre of a small tunnel made across the shaft of the bone. Examination of some of the skiagrams also illustrates another point of interest, viz. that a certain degree of recoil on the part of the bone results from the blow, since in many of them portions of the mantle of the bullet and bone fragments are seen in that portion of the track proximal to the fractured bone.
The importance of 'setting up' of the bullet is at once evident in relation to the production of wounds of an explosive type in connection with fractures of the bones. There can be no doubt that a considerable number of the most severe injuries we saw were produced by the various soft-nosed or expanding forms of bullet, also that others of an equally serious nature were produced by Martini-Henry or large leaden sporting bullets. Allowing for this, however, I think a considerable proportion were the result of deformation from bony impact, or ricochet deformities external to the body acquired by regulation Mauser bullets, and I think these bullets can be quite as formidable as any of the sporting varieties met with. The soft-nose varieties of small calibre may not set up enough to cause severe injury, while the large leaden bullets often flatten out so completely as to lose all penetrating power. As far as my impressions went, the small soft-nosed bullets needed to be travelling at a very considerable rate of velocity to be dangerous. In the form of soft-nose Mauser employed, the soft-nose was too short to allow of as successful a mushrooming of the bullet as often occurred with the regulation projectile, because, as already explained, the mantle acquires increased stability from its closed base.