The fragmentation of the missile, through its contact with the bone, indicates the great striking force of a missile which ricocheted from the bone. The general distribution of metallic particles through a wound of this class indicates certainly that the missile was unjacketed, and the destructive forces show that its sectional area was relatively larger, i. e., a shrapnel ball.
The hard metal jacket of a rifle bullet would not give off its particles in contact with the bone unless it were so greatly deformed as to have almost entirely lost its jacket. In this state the energy of a rifle ball must be so greatly reduced, through the violence of ricochet, that it would not retain enough striking force to cause its disintegration on impact with the bone. Besides, some particles of the jacket could be identified, as they are always bent or twisted so that their character is recognized in the shadow.
Plate 128.
Shrapnel—Plate 128.
LOWER EXTREMITY.
Gunshot Wound of the Left Knee,
with Lodgment of the Missile in the Joint.
The slight enlargement and moderate density of the shadow of the projectile indicates a position a short distance from the plate. A slight shadow dependent from the external condyle on the outside of the ball and a metallic marking just outside of the upper contour of the outer tuberosity indicate an injury to the joint and the path of the ball from above the outer tuberosity into the joint capsule.
The probabilities are that the ball lies between the head of the tibia and the patellar notch of the femur, but the absolute certainty of this deduction must be supported by an exposure in a lateral plane, which is shown in [plate 129].
Plate 129.