When fracture occurs at the floor of the acetabulum, the floor may be traversed by a single fissure, the line of fracture may run in a semicircular direction, or it may be angular and the bone resolved into its three primitive pieces, which, according to authors, is a very rare fracture. Sir Astley Cooper reports one case, Sanson one, and Neill another; and these cases are referred to by Erichsen, Hamilton, Agnew, and others, because they are rare. Other cases have been reported of the same kind, with either recovery or bony union which has occurred without displacement.

Fracture of the floor of the acetabulum may occur alone or be associated with fracture of the innominate bone. It may take place with or without displacement of the head of the femur.

This subject requires me to consider briefly the structure and the relations of the acetabulum. The anatomist informs us that the thinner parts of the bone, as at the floor and the center of the iliac fossa, are composed entirely of compact tissue.

The cavity may be divided into three component parts. At its deepest part, the bone is so thin that it transmits light; it is so frail that it is strange it should so often escape fracture; but the upper and posterior portion is formed by the thickest and strongest part of the os innominatum, and is capable of bearing great weight and of resisting immense force.

"The acetabulum is partly articular, partly non-articular. The articular portion is of horse-shoe shape. It is altogether deficient at the cotyloid notch, which corresponds with the gap of the horse-shoe.

"The non-articular part extends from the cotyloid notch as a rough recess in the floor of the acetabulum, and corresponds to the area inclosed by the horse-shoe." 1

This is a wise provision in the construction of this cavity, since in this way the thin portion of bone is measurably protected from violence. Were the thin and delicate portion of the acetabulum in apposition with the head of the femur, it would not be possible, without fracture, to resist violence or to

1 Morris, "Anatomy of the Joints," London, 1879, p. 318.

withstand even the weight of the body. By this peculiar and wise anatomical arrangement, the deeper portion of the cavity is protected against friction, while at the same time it is an element of weakness as regards any provision against injury from undue force or pressure. It is easy to conceive how the impact of a violent force, which would drive the head of the femur against the circular and projecting rim of the articular portion of the cavity, may cause fracture of the thinner, without fracture of the thicker portion of the bone.

The ease with which this bone can be fractured may be shown upon the cadaver. Place a piece of sole-leather over the trochanter to protect the soft parts, then strike in an oblique direction upward with a mallet, and you will fracture either the neck of the femur or the floor of the acetabulum. Fracture of the floor of the acetabulum may occur at any age, but it is most likely to occur in the young subject, and then without the application of much force. Take the case of a man who falls, perhaps but a short distance; he strikes upon the trochanter; he lies helpless, or, it may be, is able to rise; he complains of pain, and thinks he may have fractured his hip; the pain is aggravated when any attempt is made to move; he is assisted to bed; he is subjected to repeated examinations without disclosing any injury save slight contusion of the soft parts. There is no shortening, eversion of the limb, or crepitus. The patient occupies his bed for two or three weeks, gets up and walks about the room with the aid of crutches, and in two or three weeks more is able to go about without support. The injury has apparently resulted in nothing, unless it be acetabular coxalgia. There is no deformity. What could have been the nature of an injury causing such persistent pain? Was it possible to ascertain its nature? Was the pain caused by contusion of the soft or hard parts? No. Had he intra- or extra-capsular or mixed fracture? No. It perhaps ought to be suspected that the lesion was a fracture of the floor of the acetabulum without displacement of the head of the femur.

This is a type of cases which fall under the observation of every surgeon, the diagnosis of which is very difficult to make

out. The two following cases-one a case reported by Dr. Sands, the other my own case-illustrate the difficulty experienced in diagnosticating this lesion.

Dr. Sands calls his case a "perforating fracture of the acetabulum."

The patient, aged sixty-six years, had fallen in a dumb-waiter well. When first seen, he was suffering severely. In forty-eight hours after the injury, Dr. Sands noted the facts already observed by Dr. Levings; viz., the limb was not shortened nor everted; the heel could be elevated; the limb was capable of free rotary motion; the trochanter described the arc of a circle; and there was no crepitus. An autopsy revealed the fact that the head of the thigh-bone had penetrated the floor of the acetabulum, and that there was fracture of the pelvis.

My own case is reported by Dr. McBeth, house-surgeon.

Ella Smith, American and unmarried, was brought into the hospital, April 26, 1880. She had been the mother of one or more children. She contracted syphilis in September, 1879. Six hours previous to entering the hospital, she had fallen from a veranda to the pavement, a distance of thirteen feet, striking upon her right hip. Dr. Frederick and myself [Dr. McB.] gave her ether and made an examination, finding slight eversion of the toe and crepiThere was no shortening, each limb measuring thirty inches and a half. We did not consider a diagnosis of intra-capsular fracture positive, but, as relief was afforded by extension, we put on a weight of eight pounds.

tus.

April 27th. The patient was seen by Dr. Gay, who made an examination and carefully measured the limbs, finding them the same as on the night before. The patient stated to-day that the eversion of the toe was natural, having existed from childhood. There was no crepitus. The dressings by extension were therefore discontinued, thus allowing muscular action to shorten the limb if there were fracture.

May 5th. This is as early as it was deemed advisable to make a further examination, on account of dysmenorrhoea from which 1 Sands, "Perforating Fracture of the Acetabulum," "Medical Record," N. Y., 1877, vol. xii, p. 93.

the patient suffered. She was etherized, and another examination. was made. The injured limb was a trifle longer than the limb on the sound side. There was no more eversion and no crepitus. As the patient was somewhat relieved of pain by slight extension, Dr. Gay advised its continuance with use of the eight-pound weight. For a time after this, she was in a typhoid condition and evidently suffering from septicemia, having chills with fever, and a temperature as high as 105° Fahr. There was tenderness over the caput coli, and the abdomen was tympanitic. She sank gradually, with little pain, and died May 19th. There were rapid post-mortem changes.

Autopsy, May 20th; present, Drs. Gay, Diehl, Peterson, and Frederick. In cutting down upon the hip, we found a large quantity of pus evidently coming from the abdominal cavity, as it could be forced through the opening in the hip by pressure over abdomen. The vagina was filled with pus. There was a fracture of the acetabulum in three directions following the original line of union, involving a fracture of the innominate bone.

There is no sign in either of these reported cases that could possibly suggest the lesion revealed by dissection; and they therefore confirm the correctness of statements made by writers. My house-surgeon thought he detected crepitus when the patient was first examined, but crepitus was not found to exist at the examination made the next morning. It is easier to presume that he was mistaken than to believe that crepitus existed. If crepitus be ever observed, it must be in consequence of co-existent fracture of the innominate bone.

"There are no signs clearly distinctive of this fracture." If fracture of this bone can only be suspected, then diagnosis of this lesion has for the first time to be made.

There is no shortening, no eversion, no crepitus, whether there be displacement of the head of the thigh-bone or not; but there is pain in the hip, which is aggravated by movement of the joint, by pressure upon the trochanter, and by attempts to turn the patient upon the side. I have said that pain is the only sign of this fracture; it exists with a severity equal to 1 Agnew, "Principles and Practice of Surgery," Philadelphia, 1878, vol. i, p. 929.

that which accompanies fracture of the cervix femoris, but without the evidence of fracture which the latter reveals. Therefore, severe and persistent pain, in the absence of positive symptoms of fracture, is a sign of some significance in this lesion. Explorations through the rectum or vagina may assist in determining the nature of the injury.

Prognosis.-Fracture of the acetabulum without displacement of the head of the thigh-bone does not constitute a fatal, or even a dangerous injury, provided the lesion be early suspected and the patient be let alone. Fracture with displacement is not necessarily fatal, as may be shown by the following remarkable case under the care of Charles Hewitt Moore,1 of Middlesex Hospital. This, I suppose, is the case referred to by authors:

James Thomas Horsfield, who died at the age of sixty, was crushed about the pelvis, several years before, by a piece of timber. The left limb was shortened, and its principal motions were abduction and moderate flexion, while circumduction and extension were impossible.

Dissection of the Pelvis.-The left innominate bone was broken in the acetabulum into three pieces, corresponding to its original segments. These pieces were separated by the head of the femur having been driven through them into the cavity of the pelvis, where it rested upon the sacrum, below the promontory. The trochanter had worn a new socket upon the brim of the acetabulum. The right innominate bone was broken just in front of the acetabulum. Both ischio-pubal rami were broken. None of the fractures bad united with ossific matter. Owing to this fact and to the fact that the pubes had been separated from all connection with the main body of the pelvis, the former (pubes) was displaced upward (possibly by muscular action) and backward, thus materially narrowing the pelvis antero-posteriorly. The pubes was also displaced laterally; i. e., somewhat twisted. As the person, in walking, bore most of his weight upon the right thigh, the corresponding ilium, which had now no support from the pubes, became bent toward the spinal column.

'Moore, "An Account of a Case of Fracture and Distortion of the Pelvis," etc., "Medical Times," London, 1851, New Series, vol. ii, p. 484.