CI1RONIC RHEUMATIC ARTHRITIS OF THE SHOULDER JOINT.—The shoulder joint is some times the seat of this peculiar disease, though by no means so frequently as many of the other articulations. The origin of it we haxe known to be attributed to accident, such as a fall on the shoulder, or to a sprain of the joint. On some occasions the sudden exposure of the person, when overheated, to currents of cold air, has been referred to as its cause ; and in others the chronic disease of the shoulder joint bas been supposed to have originated in the lingering remains of a rheu matic fever. These are, indeed, the ordinary exciting causes of this disease in general, no matter in what particular joint it may show itself.
Symptoms. — The patient complains of feeling pains in the shoulder joint, which, like those of rheuinatism, are variable, and seem to be under the influence of changes in the atmosphere. He states that he feels a stiffness in the joint, and is conscious of a " crackling" sensation in it, particularly when he first moves it in the morning. The muscles around the articulation fall into a state of atrophy, while the bony prominences around the joint ge nerally become conspicuous from their eta. largement.
If only one shoulder joint be affected with the ordinary form of the disease, and we coim. pare it with that of the opposite side, the head of the humerus of the affected side will be observed to be somewhat elevated, ad vanced, and very generally approximated towards the middle line. When we view the articulation in profile (as it were), the amount of the advancement of the head of the hume rus is more readily appreciated. And when we look at the shoulder joint from behind, a very remarkable abnormal depression may be seen, which corresponds to the space or interval which exists between the posterior part of the glenoid cavity and the head of the hume rus. After a time, the voluntary motions of the joint become restricted within very nar row limits. The patient cannot well abduct the elbow from his side, nor elevate it nearly to an horizontal level. The motions Ile is
himself capable of communicating to his arm are chiefly confined to under movements, yet the head of the humerus is in some of these cases susceptible of an abnormal degree of mobility. Although in the ordinary form of this disease the head of the humerus will be found to be placed above its normal level, and is observed to be several lines higher than the coracoid process, still if the arm be grasped by the surgeon it can be drawn down, and the head of the bone will place itself beneath the coracoid process ; the joint will then as sume all the appearances usually assigned as the marks of the case styled by Sir A. Cooper " Partial luxation of the head of the humerus forwards and inwards." In cases of long standing, the capsular ligament becomes wider than natural, and the articular surfaces are so altered that partial dislocation of the head of the humerus occurs in other directions besides those above alluded to; but any observations we have to offer upon this part of our subject it will be more convenient fo defer until we come to speak of the anatomical characters of this disease.
Although the patient inay complain of pain in the middle of the arm, and of spasms of the muscles, of the whole extremity of the affected side, even to the fingers, yet if the surgeon elevate the arm at the elbow, and press the humerus even rudely against the glenoid cavity of the affected articulation, the patient experiences no uneasiness.
lt is very remarkable that this peculiar affection of the shoulder joint has never, as far as we have known, terminated in anchy losis, nor proceeded to suppuration ; nor has its presence excited any sympathetic disturb ance in the constitution of the patient ; yet from year to year the disease slowly but gra dually increases, until the patient is carried off by some other complaint, or dies from the mere effect of age alone.