line, where the bone is a mere shell, driving the true neck, or the remains of it, farther beneath the trochanters, and sometimes detaching the latter. The firm anterior wall resists impaction, but bends at the line of fracture as a hinge. If this hinge were ver

tical, the shaft would be only everted; while if it were transverse, the neck would be only bent and the leg shortened. But as the hinge stands at an angle of about 45°, shortening and eversion are nearly equal (Figs. 8, 9, 10). Impaction, when slight, is detected by a difficulty of inverting the foot rather than by actual eversion; and the shortening may seem doubtful.

It is needless to say that the rotated

FIG. 10.1

trochanter still sweeps through an arc of which the head of the femur is the centre, and that there is no crepitation.

1 Horizontal section of the same, showing the anterior hinge and the posterior impaction. The dotted line shows the normal position of the head. The patient who furnished the specimen from which these figures were taken was seventy-two years of age. It will be seen that the prolongation of the true neck has disappeared by senile atrophy, leaving only a few radiating lamellæ. The specimen is of exceptional interest as showing this form of impaction with little comminution or other injury of the bone.

Shortening and eversion, however inconsiderable, point directly to this lesion. A large number both of cases and of specimens are referrible to this type, impaction behind, with a hinge in front, each at its respective intertrochanteric line. In some of these specimens the neck is bent down nearly to a right angle with the shaft.

The remaining varieties of fracture of the femoral neck are susceptible of classification, and deserve, for the purpose of comparison, to be mentioned in this connection.

IMPACTED FRACTURE OF THE HEAD OF THE FEMUR.

The impacted fracture of the head of the femur is rare, and I do not believe it possible to distinguish it from that just

66

FIG. 11.1

described, even if it were desirable to do so. In three cases I have known there was the same shortening and eversion, and the same comparative ability to move the limb. A woman who died of the injury was able at all times to get into and out of bed with but little assistance, and the trochanter, when rotated, swept through its arc. There was no union. The small extremity of the cervix was rather "rebated" than impacted with the head of the femur, and the fracture

was within the capsular ligament "2 (Fig. 11).

1 Impacted fracture of the head of the femur. The patient who furnished this specimen died of pneumonia in two weeks.

2 See extracts from the Proceedings of the Society for Medical Improvement; Boston Medical and Surgical Journal, No. 1 (1875), p. 20.

The firmness of the fragments in such a case is chiefly due to the dense central cone of spongy tissue which projects from the head of the bone and impacts itself in the friable cavity of the cervix. If the cylinder of the cervical portion is simultaneously impacted into the head of the femur, around the base of the cone, immobility is doubly insured.

I have elsewhere expressed the opinion that these conditions are essential to the very exceptional occurrence of bony union of the small part of the cervix. In default of anchylosis the neck is doubtless absorbed, presenting after a time the familiar conditions of an old "ununited fracture." So that permanent lameness may result from a fracture which, by simulating impaction of the base, promises, at first, bony union, with comparatively little deformity.

1 Figs. 12 and 13,-impacted fracture of the base with inversion. The anterior view (Fig. 12) shows the neck slipped off its thick hinge, into the cavity of the shaft. To allow this, the whole trochanteric mass must have been detached, as seen in the rear view (Fig. 13).

IMPACTED FRACTURE OF THE WHOLE BASE OF THE CERVIX, WITH INVERSION.

The very rare impacted fracture of the neck with inversion, instead of eversion which is the rule, occurs when the neck in front slips off its hinge into the cavity of the shaft. This is hardly possible, as I have elsewhere shown, unless the whole posterior intertrochanteric mass, including the trochanters, is fairly detached (Figs. 12, 13).

UNIMPACTED FRACTURES.

FRACTURE OF THE SMALL PART OF THE CERVIX OF THE FEMUR.

THE fracture of the small part of the cervix of the femur, which has been usually described as the most common fracture of elderly persons, and erroneously as deriving importance from being within the capsular ligament, is a loose fracture, with no interlocking to maintain the immobility of the small extremities, even were they disposed to bony union. Familiarly characterized by increased motion, great pain and disability, much shortening, marked eversion, and the rotation of the shaft upon its axis instead of through an arc, it is not likely to be mistaken even at first sight. But its relations to the capsular ligament are probably uncertain, owing to differences in the size and insertions of the latter.

COMMINUTED FRACTURE OF THE TROCHANTERS AND SHAFT.

Lastly, when the trochanteric portion of the femur is comminuted, the detached neck and head of the bone may be very variously placed in bony union, both as to angle and as to the part which becomes subsequently attached to the shaft.

In completing the list of injuries to be borne in mind while examining a hip with reference to impacted fracture, we may enumerate dislocation, sprain, crack, the rare separation of the epiphyses, and the fracture of the acetabulum into the pelvis.

TREATMENT.

A few words of a practical character may be added here. Apart from dislocation, the main object of examination is to decide, with reference to treatment, whether a fracture is loose or impacted. I have demonstrated here and elsewhere the following points, illustrating the difficulty of further diagnosis:

1. The common impacted fracture of the base of the neck and the rare one of the head may be indistinguishable from each other.

2. A fracture seemingly impacted and promising bony union may yet result in ligamentous union with corresponding lameness.

3. In loose fractures with great shortening, it may be sometimes difficult to distinguish a fracture of the small part of the neck, which does not promise bony union, from that of the trochanters, which does.

But while an accurate diagnosis of such cases is sometimes absolutely impossible, no embarrassment need be felt in the treatment of these injuries. Their treatment is simple.

If to extend a limb means to draw it down, impacted fracture and whatever resembles it should never be extended, but only steadied by weight or splint. On the other hand, a loose fracture with decided shortening should be first drawn down to something like its normal length. Or, more briefly, treatment consists in immobility, with the previous extension of a loose fracture.