version, which for all practical purposes is due to the outer branch of the Y ligament. Upon this, in fact, inversion ultimately depends; without its rupture there can be no eversion, and after its laceration the other fibres of the capsule have comparatively little strength. The rupture of the inner branch of the Y lig ament does not materially change the attitude of the limb. The shortening varies with the position of the head of the bone. Sometimes there is little; sometimes it amounts apparently to two inches or more; but, as Malgaigne remarks, it is then complicated by flex ion, and is more apparent than real.1 The accompany FIG. 6.2 ing figures (6 and 7) are intended to illustrate the operation of the Y ligament in limiting the range of the femur, and the consequent amount of shortening. At its lowest point, the head of the bone corresponds to the lower part of 1 The elongation or shortening of a dislocated thigh may, like that of the arm, be real or only apparent. If the head of the bone is luxated downward, the limb should be longer; but flexion or abduction of the shaft approximates the usual points of measurement. To this source of error should be added the tilting of the pelvis in the femoral luxations. 2 Figs. 6 and 7,-dorsal dislocation. These two figures are intended to show the possible range of the dissected femur when limited by the Y ligament alone. (From photographs taken in 1861.) the ischiatic notch, while it may rise upon the dorsum about an inch and a quarter above it. The former position is that most frequently occupied in dorsal luxations, the head of the bone being usually confined to the neighborhood of the socket by the unruptured muscles and by the capsular and Y liga FIG. 7. ments (see Fig. 5). Should the femur have been thrust up ward to a higher point, it might again gravitate to the level of the ischiatic notch unless engaged in the interstices of the small rotators. From examination of eleven specimens of dorsal dislocation, Malgaigne1 infers that the head of the femur generally corresponds to the ischiatic notch, and that the iliac luxation of Cooper is a pure hypothesis, while his plate illustrating it is imaginary. It will be observed that the dorsal dislocations here given in woodcuts from photographs exhibit an inconsiderable shortening. If, then, there be a fixed inversion of the limb with shortening, and the head of the femur is felt upon the dorsum, little desirable information is to be gained by measurement unless in exceptional or doubtful cases, inasmuch as a primary dislocation upon the dorsum practically signifies one and the same thing, whether directly backward behind the acetabulum, or 1 Traité, etc., p. 820. obliquely upward and backward to the full extent of the Y ligament, if this remain unbroken. A more useful indication is the degree of its mobility. The thigh can always be flexed, and then its mobility varies with the extent of the laceration of the capsule and the adjacent tissues which bind the neck of the femur to the pelvis, — an important point, best determined by the extent to which the flexed limb can be abducted. If the bone has escaped by a large aperture in the capsule, perhaps with rupture of the obturator tendon, there will be a comparative freedom of motion and less inversion; while if the laceration is small, the movement will be restricted and the limb comparatively rigid. By flexing and rotating the thigh, the head of the bone may be felt upon the ilium, unless the patient is very fleshy or the parts are greatly swollen; but when this sign is wanting, a differential diagnosis can be based on other indications. Thus, although it is practically needless to distinguish the dorsal dislocation from the one below the tendon, the latter is generally characterized by a more advanced position of the knee, the limb being more inverted, and crossing the sound thigh at a higher point. On the other hand, the other regular dislocations and the fractures exhibit eversion, if we except the fracture of the neck accompanied by inversion,1— an accident so rare that it need hardly be taken into account, and some of the fractures of the pelvis. In the dorsal dislocation, however much the knee may be advanced and the leg inverted, even when the head of the femur is below the tendon, the thigh may be depressed by manipulation until the knees lie almost upon the same plane; and in some cases, where, as in a female, the legs are knockkneed, or where the knee-joint is loosely articulated, or in an 1 See p. 147 of this volume; and also a Practical Treatise on Fractures and Dislocations (p. 354). By Frank Hastings Hamilton, M. D., etc. old dislocation, the foot may seem not to be inverted. But the inversion of the patella, and especially the degree of resistance in everting the foot, betray the still unreduced luxation, even when the position of the limb has been much improved by efforts at reduction, which, though unsuccessful, have lacerated the capsule and loosened the muscles. This is especially true in the case of a fleshy subject, where the marks are obscure. DORSAL DISLOCATIONS BETWEEN THE ROTATOR MUSCLES. It has been said that the dorsal dislocation is often secondary, the head of the femur having first escaped below the socket. But the head of the bone may also reach the dorsum at once by a backward thrust in the direction of its axis, which is also likely to engage the head in the muscular interstices of the rotators. Autopsies have hitherto failed to show whether in such a high dorsal dislocation the internal obturator, with other inward rotators, is usually ruptured, or whether the head of the bone usually emerges above the internal obturator; but I have expressed the belief that the outward rotators are often ruptured, both by the original injury and by the protracted manipulation accompanying the use of pulleys, and that this lesion is by no means serious. It may, indeed, be difficult to distinguish between the flexion and inversion of a femur engaged above the obturator muscle and those of one in the act of ascending from the position of a luxation near the tuberosity to that below the tendon. But this distinction is practically unimportant, since, by circumduction of the limb, a way can be cleared for the head of the bone from any point of the dorsum within the range of the Y ligament round to the thyroid foramen. The head of the femur has been found between the obturator internus and the pyriformis, which lies above it, and has even passed still higher beneath the pyriformis, emerging between it and the gluteus minimus.1 The bone is then drawn so far backward by the obturator tendon that the outer branch of 1 See an interesting case mentioned by M. Parmentier (Bulletin de la Société Anatomique, 1850, p. 177). The limb was "adducted and shortened three quarters of an inch. The femur was luxated between the pyriformis muscle and the obturator internus, the head reaching to the ischiatic spine. The button-hole thus formed opposed the reduction of the luxation in the dissected specimen." Another interesting and exceptional case has been reported by Dr. Servier. (See Bulletin de la Société de Chirurgie, 1863, p. 485. Report of M. Legouest.) The head of the femur, instead of escaping between the obturator internus and pyriformis muscles, as in the case described by M. Parmentier, was here found above the pyriformis, between this muscle and the gluteus minimus. The signs, so far as can be judged from the account given, were those of the dorsal luxation. The capsule was ruptured posteriorly. It has been remarked that there is great difficulty in producing these luxations in the dissected specimen without rupturing the slender outward rotators; but if the head is made to emerge between them, either by rotation or by a direct backward thrust of the shaft, it is so embraced by the muscles, and also by the capsular orifice, which is then likely to be small, that the movements of the limb are comparatively restricted, and the muscular obstacle to their reduction may be considerable. I do not know how such cases can be identified with certainty during life. If the head of the bone has escaped by rotation of the shaft inwards, it may perhaps be reduced by outward rotation, with previous or subsequent flexion of the thigh, and thus brought to a point below the socket; although the surer way is to take the risk of rupturing all these smaller muscles by outward circumduction of the flexed limb, accompanied with outward rotation, and then to reduce the bone as usual. M. Guersant (Notices sur la Chirurgie des Enfants, Paris, 1864–77), reporting two cases which occurred under his own observation, and referring to a paper of M. Chapplain, proposes a distinction between superficial and deep iliac luxations. Such a difference would be difficult to discover in practice, either in a fleshy or a thin subject, but may have some foundation in the muscular complications just alluded to. Mr. Wormald reports a case of dislocation. originally on the ilium, in which, by the use of pulleys, the bone was "thrown" upon the sciatic notch, whence it "could not be reduced." (Medical Times and Gazette, Aug. 16, 1856, p. 170.) I am at a loss to explain this case, if the facts are accurately given, except upon the hypothesis that muscular button-holes, together with horizontal extension, determined the result. In a case of "Dislocation of the Thigh-Bone upward and backward, |