Differential Diagnosis.—Thst.ocAnoisr. —In dislocations there is abnormal mo tion where there was motion before. In fractures there is motion where there was none before. Moreover, if, in disloca tions the range of motion is increased in one direction, it is usually diminished in the opposite direction, while a fracture usually gives abnormal mobility in all directions. Crepitus is pathognomonic of fracture.
CONTUSION.—Position and pressure for a few days ought to reduce the swell ing of the soft parts sufficiently to permit a satisfactory examination. Contusions of the hip form the exception. If even the X-rays fail to clear up the diagnosis satisfactorily, the only safe treatment is that for fracture.
If every "dislocated wrist" and every "contused hip" were regarded and treated as a fracture, the world would be none the worse for it.
Etiology. — PREDISPOSING CAUSES.— Sex, age, and occupation are remote pre disposing causes of fracture. Men suffer more frequently from fracture than women, for they are much more often exposed to injuries of all sorts. Yet after the age of seventy, women suffer many more fractures than men, chiefly of the neck of the femur. Again, while by far the greater number of fractures occur in the first three decades of life, the propor tion of fractures per capita is at its maxi mum at about the age of sixty. More definite predisposing causes, however, reside in the anatomical and patholog ical condition of the bones and the sys tem in general. Normally, the shape, structure, and functions of various bones expose them more or less to fracture, the liability to which is increased by the changes incident to advancing years. The curves in the long bones and their broad spongy ends, so well adapted to transmit the minimum of danger to more vital organs, render them, for that very reason, more liable to give way under ex cessive violence. Seventy-six per cent.
of all fractures occur in the ribs, clavicle, forearm, hand, and leg, while the upper extremity, the weapon of offense and de fense, receives 51 per cent. of the total. The middle aged and the aged, while less exposed to trauma than the young, re ceive more than their share of fractures, partly because of their decreased agility, the normal stiffening of their muscles, but mainly on account of the normal changes in the osseous system. As age advances, the spongy and the compact tissues of the bones become gradually rarefied, not by any changes in the pro portions of their bony constituents, not by any deposit of lime-salts, but by an actual diminution of the amount of the bone-tissue. Such changes are patho logical only when they occur at an early age. In a few cases an unlimited tend ency to this early bone-rarefaction has been observed. Such fractures usually heal kindly, and refracture through the line of union is the exception, although, in the more pronounced forms, the pa tient may scarcely have convalesced from one fracture before some slight acci dent disables him with another one. A similar bone-fragility may be acquired through prolonged disuse or consequence of lesions of the nervous system.
Rachitis in children and in later days syphilitic bone-lesions, bone-tumors, and inflammations act as predisposing causes of fractures, and notably delay, if they do not entirely prevent, the process of repair. The existence of rheumatism as a predisposition is very doubtful, the pathological connection between the two not having been demonstrated, and the clinical history of "aches and pains" probably a mere coincidence.