completely removed, exposing the bone in an ulcerated condition; and when the system has long borne up under the disease, the greater portion of the head, neck, and even of the trochanter, is destroyed, the extremity of the bone being completely altered in form, and composed of a loose and spongy structure. A similar disorganisation occurs in the acetabulum; the mucous gland is destroyed, the cartilage is often wholly removed, and the margins of the acetabulum absorbed, a large and flat ulcerated depression merely being left for the reception of the diseased femur; in other instances the margins remain unaffected, whilst the ulceration proceeds in the centre, and the cavity is thereby much deepened. Not unfrequently the ulceration proceeds farther, and an aperture is formed in the acetabulum, so that matter accumulates within the pelvis. The opening is sometimes so large that the femur is protruded through it. When matter has formed in the soft parts round the joint, portions of the bones of the pelvis, in contact with the pus, are ulcerated to a greater or less extent, and sometimes these ulcers are surrounded by deposits of new bony matter.
From such changes in the osseous parts of the articulation the limb is shortened, sometimes to a great degree, though no dislocation has occurred. Indeed, dislocation is by no means so frequent a cause of the shortening as is generally believed.
If the head of the femur has been dislocated, and if the disease in the joint has afterwards subsided, the acetabulum is found to be much contracted, with its margins smooth and little elevated, and, if the patient survive for a number of years, it will be almost wholly obliterated. But a portion of the dorsum of the ilium, upward and backward, which is the most frequent dislocation in this disease, is gradually absorbed, so as to form a sort of glenoid cavity for the
reception of the femur, the extremity of which becomes more solid in texture, and more smooth on its articular surface. The remaining neck of the bone is in the sketch here given turned forwards, and must have given rise to great eversion of the toes. I have seen one other specimen of this form of luxation. The limb is generally, however, inverted; and what remains of the head of the bone consequently points backwards. The consecutive luxation occasionally, also, though rarely, takes place upon the pubis. Whilst a depression is thus formed, new bone is sometimes deposited round its margins, whereby the cavity is increased in depth, so as to resemble somewhat the original acetabulum, the new deposit having become smooth and of a regular form.
ON CERTAIN ALTERATIONS OF FORM IN THE HEAD AND NECK OF THE THIGH BONE.
When treating of atrophy of the articular cartilages, it was observed that, in the latter stages of the disease, the subjacent bone was liable to become denuded, and its articular extremity more or less deformed. Now one of the most interesting of these changes occurs in the head of the thigh bone, which becomes polished on its surface, flattened and expanded, with a corresponding alteration in the acetabulum. In other cases the head of the thigh bone is somewhat elongated, and the acetabulum becomes deepened in proportion, by a deposition of new bone around its margin, as shown in the preceding
page, frequently to such an extent as to render the removal of the head of the bone, even after the removal of all the soft parts by maceration, almost impossible without fracture of the edge of the socket. The head of the bone may also become still further misshapen, and anchylosis result; while in some instances the new bony matter presents in the form of nodosities, sometimes projecting towards the cavity of the articulation. This cut represents a section of the upper end of the femur of a labouring man, aged 49, who had fallen on the trochanter ten years before death, and became gradually lame in consequence, with shortening of the limb and anchylosis of the joint, although he had never been confined more than a day or two on account of the injury.