C. They are often impacted, which means that one fragment is driven into and more or less embedded in the other. This impaction or interlocking of fragments occurs usually in the neck of the femur and the lower end of the radius. In the former locality it is advisable not to interfere with it; in the latter it should always be dislodged in order to restore the fragment to its proper position ([Fig. 276]).
D. As to their nature and location, fractures are referred to as pathological, gunshot, intra-articular, or extra-articular, etc., the latter terms referring to involvement of a joint. If blood can escape from the site of the fracture into a joint cavity, or if synovial fluid can escape from the latter into the former, then the fracture is called intra-articular.
Pathological fractures imply preëxisting disease. This may be constitutional, as in the case of the fragilitas ossium, already described in the chapter on the Bones, or it may be due to some secondary deposit of cancer or a primary sarcoma. In adults, especially those with a cancerous history, any spontaneous fracture, or even one occurring with trifling violence, should lead to suspicion of a metastatic focus in the bone at the site of its yielding. The atrophic changes which notably occur in various bones as old age comes on lead also to a condition which is pathological, i. e., it permits of fracture from what would appear to be a trifling injury.
Gunshot fractures are practically always comminuted, save perhaps some of those inflicted with the modern military weapons. A Mauser bullet will frequently make an almost clean perforation, but the gunshot fractures met with in civil practice are almost invariably comminuted, especially those of the skull ([Fig. 277]).
E. The term compound is applied to any fracture in which there is wound of the soft tissues and so located as to permit access of air to the injured bone. There is a distinction between a compound and a complicated fracture. A fracture of the femur accompanied by a gash or extensive wound, so long as air cannot come in contact with the broken bone, would be described as a fracture of the femur complicated by a lacerated wound. On the other hand, if through the slightest puncture of the skin, even at a distance from the fracture, air can even theoretically enter and come in contact with bone surfaces at the site of the fracture, such an injury constitutes a compound fracture. This distinction is not a trifling one, for upon the exclusion of air, which to a certain extent means the exclusion of germs, depends very much the rapidity and perfection of recovery. Compound fractures are all dangerous in proportion as they permit of infection, and while air infection is not necessarily the most serious of any, it nevertheless is often sufficiently so to set up sepsis and interfere with consolidation, even if it does not prevent it. Fractures are made compound by direct violence from the outside or by indirect violence, as where a bone end perforates soft parts and the skin. Even if a sharp point of bone thus protruded from within is quickly drawn back again it is enough, since both the skin and the air in contact with it are sources of germ activity. Thus it may happen that a slight and apparently trivial injury of this kind is more serious than one which is extensive.
Fig. 277
Skiagram of compound comminuted (gunshot) fracture of elbow, inflicted with a Dumdum bullet. Illustrating the extreme of comminution. (Lexer.)
F. Epiphyseal separations constitute a somewhat distinct form of injury, having at the same time the importance and dignity of fractures in the truer sense of the term. In the chapter on Diseases of the Joints will be found a [table] of the ages at which epiphyses unite. In childhood and youth a fracture near the joint is most likely to partake of this character, and it is of importance that it should be recognized as such when it occurs. Injuries occurring beyond the ages mentioned in the table are not likely to be of this character unless ossification is delayed by some morbid process.
By virtue of their occupations and habits men suffer fractures more frequently than women. Fractures are, moreover, ten times as frequent as are dislocations. The aged, by virtue of their atrophic changes, are more subject to fractures than others. Fracture in the vicinity of certain joints predisposes as well to dislocation of these joints, and it often happens that the treatment for the dislocation is reduction and treatment of the fracture. So far as the external causes of fracture are concerned they are frequently referred to as (a) fracture by external violence, and (b) fracture by muscle activity. The former are easily explained; the latter occur from excessive muscle action, as in violently throwing a ball, or, as in one case with which the writer was conversant, where a colored preacher in the vehemence of his gesticulations fractured his own humerus. Obviously the long or large bones are more liable to fracture than those which are short and irregular. Certain bones, especially the clavicle, are peculiarly exposed.