The explanation of the circumstance why the superior and external part of the capsular liga ment has been found perforated by a large cir cular opening, through which the head of the humerus can pass, appears to be, that the effects of the loss of the tendon of the biceps are such, that the head of the humerus is at once elevated by the deltoid, and kept habitually pressed up against the under surface of the acromion. The coraco-acromial vault now becomes the articular socket for the head of the humerus, more than the original glenoid cavity. The head of the humerus assumes altogether a new form ; its summit is ex panded, and at the same time smoothed by the constant effects of use and friction ; the anatomical neck is encroached upon, and gradually the whole summit, including the, great and lesser tuberosities, becomes articu lar, these latter eminences being, as it were, ground down and covered with a porcelainous deposit (fig. 428.). As the upper portion of the circular groove, called the anatomical neck of the humerus, which norinally gives attachment to the capsular ligament of the joint, has been removed, this attachment of the capsule must be destroyed, and a large opening will be found in it. This occurrence is well illustrated by a case of chronic rheu matic arthritis of the shoulder joint, described by Mr. Hamilton Labatt, who entitles the case, " An excellent specimen of that chronic disease of the shoulder joint which old people are liable to ; as also an example of partial luxation upwards, the result of slow disease."* The history of this case, as of almost all of the same kind published, was unknown. The subject ikas a female aged 60, brought into the College of Surgeons for dissection ; the muscular systein well developed. The com mon integuments had been removed when Mr. Labatt was called to witness the dissec tion, and the deltoid muscle was cut across and thrown back, when the attention of the dissector was attracted by the head of the humerus, which was exposed and firmly sup ported against the under surface of the acro mion process by the lips of a vertical rent in the capsular ligament, which was otherwise healthy, firrnly girding the anatomical neck of the humerus. The articular cartilage of the head of the humerus had been universally eroded. The head of the huinerns had been increased in size by the addition of an osseous margin, which overhung the anatomical neck of the humerus. Several cartilaginous bodies, connected to the surrounding fibrous tissues, projected into the cavity of the joint. The larger were pedunculated and pendulous, while the smaller were attached by broad sur faces. The articular part of the biceps tendon had disappeared. The capsular ligament was thickened ; and the longitudinal aperture al ready mentioned, which existed in the upper part, was sufficiently capacious to allow the head of the bone under certain circumstances to pass with facility from its natural situation upwards, and to come in contact with the under surface of the acromion process. The coraco-acromial articulation of the same side, as well as several of the other articulations in this subject, exhibited unquestionable traces of having been affected with the same dis ease.* When a specimen of chronic rheumatic ar thritis of the shoulder joint, such as the pre ceding, has been met with, by anatomists not familiar with the ordinary anatomical charac ters of the disease, it is usually mistaken for a case of partial displacement of the humerus upwards, the result of accident. We find many such cases and such mistakes recorded. Although the history of Mr. Labatt's case was unknown, the appearances which the head of the humerus presented were sufficiently cha racteristic to clearly designate the true nature of the affection, independently of the condi tion alluded to of the coraco-clavicular and other articulations, so many concurring cir cumstances sufficiently proved that, in the above case, the shoulder had been long affected by the chronic rheumatic arthritis, and that this, and not accident, was the source of the partial luxation upwards which existed. , In April, 1840, Dr. Robert Smith, who is well acquainted with this disease,laid before the Surgical Society of Dublin an account of the post-mortem examination he had made of an aged female, who died of an internal organic disease in the House of Industry. She had been long affected with a partial displacement upwards of the right humerus, which was the result of chronic rheumatic disease. He pre sented a cast of the upper part of the body, taken after death, showing the degree of ele vation of the summit of the humerus on the affected side; and also exhibited a prepare tion of the shoulder joint to the meeting. The post-mortem examination had been made a few weeks previously to Dr. Smith's com munication of this case to the society. " It may be seen," he said, 44 from the cast, that in this case there was a remarkable contrast in the appearance the two shoulder joints pre sented : on one side, the head of the humerus was placed far above the level of the coracoid and acromion processes. Many persons," he added, " in viewing the cast and accompanying preparation, might consider the specimen as one of some unusual form of congenital mal formation, or the result of accident ; but the abnormal appearances were clearly the result of that peculiar affection of the joints, of which so many specimens had been elsewhere brought forward by the president in the chair (Mr. Adams), and which disease he has denominated chronic rheumatic arthritis.' "
Dr. Smith added that his chief reason in bringing forward the case was, that it pre sented some peculiarities he had not observed in other specimens of the same disease, as it affects the shoulder joint : he had often before noticed the elevation of the head of the bone as a symptom of this affection, but had never seen the elevation to the same degree it had amounted to in this case. The head of the hunierus was displaced upwards, even to a point above the level of the clavicle and acro mion process. The capsular ligament was enlarged, and as thin as if the synovial mem brane alone constituted it. Superiorly, this capsule was altogether deficient : a large aper ture was here found, which permitted the head of the humerus to pass upwards, as already mentioned ; the tendon of the biceps was perfect, but was thrown off the head of the bone inwards. The cartilage of the head of the bone was abraded in several places, and osseous depositions had been formed in the vicinity of the bicipital groove, and around the margin of the articular head of the humerus, as is usually the case in exaniples of chronic rheumatic disease. Mr. Smith observed, that the preparation showed a large deficiency in the upper part of the capsular ligament — a fact not before observed by him, until he had seen Mr. Labatt's preparation ; and even then he was disposed to attribute the deficiency to some injury received in removing the parts. He had therefore taken the greatest care in removing the preparation just exhibited to the society, and had found that in dividing the deltoid muscle he had cut at once into tbe cavity of the joint.
Dr. Smith and the writer have lately care fully examined this preparation, and find that the acromion process has been much reduced in thickness ; its under surface is excavated, and denuded of all periosteal covering ; this process is divided into two portions, as if a fracture had traversed the original line of the junction of the epiphysis with the rest of the process : half an inch in extent of the bone is thus separated from the rest, and seems merely retained by a ligamentous connection.
The deltoid and triangular ligament were relaxed :—" The shoulder joint presented a remarkable degree of mobility in this case ; and the head of the humerus of the affected side could be pushed half an inch higher than its fellow." The great peculiarity in this ease Dr. R. Sinith thought consisted in the cir cumstance that the tendon of the biceps was not, as it usually is in cases of this chronic disease, absorbed, but was in a perfect state of integrity as to structure.
This tendon having been thrown off' the bead of the humerus, and displaced inwardly, its normal function to restrain the ascent of the humerus, through the medium of its mus cular connection, was as much annulled as if it had been removed altogether, as it usually is, under the influences of this chronic dis ease.
Questions here naturally arise : Can the tendon of the biceps be dislocated from its groove by accidental violence ? and if so, Shall the consequent diaocation of the head of the humerus be in the direction upwards, exactly as it was in the preceding case, which was evidently an example of the displacement of the tendon froni disease.
Mr. John Soden, junior, of Bath, has pub lished a case, accompanied by some interesting remarks, the objects of which are to prove that the tendon of the biceps may be dislocated by accident, and that a partial displacement of the head of the humerus upwards must im mediately follow.
311' . John Soden': case. — Partial disloca tion upwards. — " Joseph Cooper, aged 59, was admitted into the Bath United Hos pital, November 9, 1839, on account of a compound fracture of the skull. His death afforded an opportunity of examining an old injury of the right shoulder, the symptoms of which had been always involved in great ob scurity, and which occurred in the following manner :— " In the month of May-, 1839, the deceased (six months before his death) was engaged in nailing down a carpet, when, on rising sud denly from his occupation, his foot slipped, and he fell backwards on the floor. In order to break the force of the fall, he involuntarily placed his arm behind hint, and by so doing received the whole weight of the body upon his right elbow ; that joint, the only one struck, received no injury, for the shock was instantly transmitted to the shoulder, and there the whole effects of the accident were sustained. Acute pain was immediately ex perienced, and the man supposed he had either suffered a fracture or a dislocation, but finding that he could raise the arm over his head, he felt reassured, and endeavoured to resume his work. The pain, however, com pelled him to desist, and he went home." " When I saw him," says Mr. Soden, " on the following morning, the joint was greatly swollen, tender to the touch, and painful on very slight motion. There was then no pos sibility of his placing his arm over his head, as he had done immediately after the acci dent. I satisfied myself that there was neis ther fracture nor dislocation of the bones, and not suspecting the existence of a more specific injury than a severe sprain, I set down the case as such, and avoided the un necessary pain of further examination. Un usually active means were necessary to sub due the inflammation, and at the end of three weeks, though the swelling was much reduced, the tenderness in the . front of the joint, and pain on certain motions of the limb, were scarcely less than on the day after the occurrence of the accident.