The fracture healed well, with the deposition of a large mass of provisional callus. The musculo-spiral nerve was united by suture some three months later.
Fig. 53 a.—Diagram of "butterfly' type
Plate VIII. exhibits an oblique fracture of the lower part of the shaft produced by a bullet passing at a low rate of velocity. It does not widely differ from a perforation, and the illustration possesses some further interest as showing the deviation of a bullet likely to occur when a bone lies in its course. Although the velocity with which this bullet was travelling must have been very low, when the bone had been traversed the deviation in its course was slight. A few bony fragments from the compact tissue of the posterior surface of the humerus have been carried into the distal portion of the track.
Fractures of the various prominences of the lower articular extremity were not uncommon, but deviated little from the types with which we are familiar in civil practice; the after results were good, both as to union and movement of the elbow.
Explosive wounds of the soft parts were not infrequent in the arm, and fig. 48, p. 158, exhibits an extreme example. The humerus in respect of depth of covering, however, comes between the femur and the bones of the leg and forearm; hence such injuries were not so easily produced as in the latter segments of the limbs.
In connection with the subject of fractures of this bone, one word must be added as to the occurrence of the most characteristic of its complications, musculo-spiral paralysis. This was frequent in every position of the fracture, and came on either immediately, or, at a subsequent period, as a result of callus irritation or pressure. Its frequency is only what would be expected when the nature of the fracture is considered, but the chief interest of the condition lay in the difficulty of certainly detecting it in the initial stages of the cases; this depended on the fact that in many of them the local shock to the limb was so severe that the function of the whole of the muscles was lowered, or in some cases, although the musculo-spiral was the nerve chiefly affected, the other large trunks had also suffered concussion or contusion. In consequence of this difficulty the actual localised paralysis often only became evident at the end of a week, or even more, when there was difficulty in deciding as to whether the paralysis was primary or due to secondary trouble. In the fracture illustrated by skiagram, plate IV., the nerve suffered complete division, and was united some three months later, improvement in the symptoms being very slow. The latter was a common experience, and although not unusual in civil practice, I think it is more marked in these injuries as a result of the more widespread character of the nerve lesion.
