In one peculiar affection (arthritis urica), the cartilage (in other respects but little altered) has a perfectly white, chalky color, which is distributed in the form of spots of varying size. Examination with the microscope shows that the appearance is due to a deposit of crystalline urate of soda in the form of very fine needles, both within the cells and in the intercellular substance. It has already been stated that the consistency of the cartilage is diminished in malacia, which precedes the erosions, and in fibrous degeneration. In the latter condition the consistency as well as the appearance, resembles that of velvet. The deposition of uric acid salts produces an increased hardness of the cartilage, but at the same time a certain amount of brittleness.
<Callout type="important" title="Important">The articular ends of the bones lie exposed to a greater or less extent, according to the quantity of cartilage which has been destroyed. The condition of their surfaces permits a general conclusion to be drawn as to the acute or chronic character of the process.</Callout>
In chronic affections, the surface of the bone appears as a compact but thin layer, so that none of the spongy portion is to be seen, while in acute processes the spongy masses are quite superficial and are usually in a state of disintegration (caries). In the latter case it is usually possible to determine the condition of the bone by the contents of the joint (pus), as extremely small pieces of necrosed bone are found in suspension, and produce a sand-like feel. Their bony character is easily determined by the microscope.
The shape of the articular ends of the bones is very much altered in acute and chronic affections, especially in the latter. The alteration of shape in the former is easily understood to result from the constant superficial detachment of the cancellated tissue of the articular ends; in the latter form the cause of the alteration of shape is by no means so evident.
The color of the surface of the bone in chronic affections, 26 402 DIAGNOSIS IN PATHOLOGICAL ANATOMY. is that of ordinary bone ; in the acute it is sometimes red, especially when granulations are present, sometimes yellowish when suppuration is taking place, and again greenish, (vhen the process is one of an ichorous character. The consistency of the surfaces is soft in proportion to the number of granulations.
<Callout type="risk" title="Risk">Ball-and-socket joints require further attention from the changes which may take place in the socket (acetabulum). The dimensions of the latter may be increased or diminished.</Callout>
The socket may be widened by acute or chronic inflammatory processes, and deepened by the formation of bone at the periphery, or by erosion and ulceration at the bottom, or by both these processes combined; the latter may even result in perforation. A diminution in the size of the socket resulting in its total obliteration, and at the same time accompanied by a conversion of the articular cartilage into fibrous tissue, occurs when the head of the bone is dislocated.
In such cases a new socket, which is more or less perfectly formed and even lined with cartilage, is found near the old one, at the point where the head rests upon the adjoining bone. All of these processes occur principally in the hip-joint (coxitis, malum coxae senile).
<Callout type="tip" title="Tip">Most of the affections of the joints are of an inflammatory character, and all the parts are more or less involved, for when one is affected (synovial membrane, cartilage or bone) the others become so very quickly.</Callout>
Inflammations are divided into the simple serous or fibrino-serous and the purulent form. In both the synovial membrane is either the first or one of the first parts affected. The first group is found in rheumatism, especially, and is characterized by a reddening and swelling of the synovial membrane, especially of its folds, and by a disturbance of its secretion.
<Callout type="warning" title="Warning">When much serous fluid is secreted, it is termed hydarthrus ; an excess of fibrine on the other hand characterizes arthritis rheumatica sicca; if abundant so as to form a membrane covering the bones and cartilage, the condition is spoken of as a fibrinous or croupous arthritis.</Callout>
Besides the synovial membrane, the bones, periosteum, and surrounding connective tissue are involved, being swollen, reddened, etc. The cartilage remains unaffected till the later stages of the trouble, when chondromalacia occurs.
<Callout type="important" title="Important">Ossification of the fibrous adhesions is seldom met with.</Callout>
Chronic rheumatic inflammation may be defined as an affection of the joints, which is characterized on the one hand by a retrograde metamorphosis of the cartilage, even destruction of the articular end of the bone, usually without any excessive secretion; and on the other, by a growth of periosteum around the articular surface (peripheral bone formation), and also of the perichondrium (supracartilaginous exostoses, especially on the vertebral column).
In the early stages the cartilage presents the cell proliferation already described; then fibrous degeneration and softening of the intercellular substance, which gives to the surface a velvety appearance. Later, the articulating surface of the cartilage has disappeared to a greater or less extent, but the edge is surrounded with a projecting ruff of cartilaginous nodules, and the bone becomes eroded, and deformed in the manner already described.
Finally, the synovial membrane also becomes involved, and papillae are formed which may contain fat, cartilage, or bone, and have suggested a resemblance between the membrane and a sheep's skin (Volkman). The increase in the amount of secretion (secondary hydarthrus), which is sometimes met with, is to be attributed to the affection of the synovial membrane.
The villi may become detached in the manner already described and remain as free bodies in the joint; still the detachment of peripheral nodular growths and the consequent formation of loose bony bodies occurs in this affection. The principal seat of this process is in the hip-joint (malum coxae senile), where the socket may be worn away, and spontaneous dislocation with the formation of a new socket may occur.
Certain forms of chronic arthritis are due also to syphilis^ and are especially characterized by the fact that when an erosion occurs in the bone, it is covered by a thin layer of connective tissue which extends through the cartilage into the bone; a sort of scar results, which resembles the syphilitic cicatrices in other localities, owing to its irregular notched shape. Adhesions between the two articular surfaces are also frequent in this form.
Purulent articular inflammation may be acute or chronic. Acute purulent arthritis, unlike the forms already described, is rare, seldom occurring except in those cases where there is a special predisposition; its origin is either rheumatic, of ten traumatic, or is due to conditions present elsewhere, metastatic, in which case, as in the rheumatic form, many joints are affected (the polyarthritis of certain writers).
It originates in the synovial membrane (purulent synovitis), but very soon extends to the cartilage and bone. The pus in the joint may be laudable or not (sanious, ichorous); it is usually ichorous in the metastatic form, and very often so when the disease is of traumatic origin, or has extended from some other point.
Its character in these cases can usually be explained by a communication with the air or with ichorous abscesses, while in the first instance it must be attributed to the infective nature of the material which excites the disease. It is very probable, though rarely demonstrated, that emboli may act as a cause, for they produce purulent inflammation in other localities in the same general processes (ulcerative endocarditis, pyaemia, puerperal fever, etc.) in which the metastatic forms of synovitis occur.
The synovial membrane is much swollen, reddened, and covered with a layer of pus, appearances corresponding with the violence of the inflammation. With the microscope it is found to be completely infiltrated with granulation cells.
Perforations, whether primary or secondary, are of very frequent occurrence, and often of large size; those of secondary origin are situated at the points where the capsule is thinnest. Periarticular abscesses are then found outside of the joints and are frequently of large size. The cartilage always becomes involved in purulent synovitis. In recent cases it is found to be thinned, and may even disappear, the bone being laid bare, especially at the sides where it is normally thinnest, and at the points of greatest friction.
The cause of the disappearance is usually malacia (chondritis and ulceration of the cartilage, according to Rindfleisch and others), less frequently necrosis or separation resulting from osteomyelitis. When the bone becomes involved the arthritis becomes a caries. The superficial layers of spongy tissue assume a yellow color, owing to the formation of pus among the trabeculae, and the cancellated structure is necrosed (molecular necrosis of Volkmann).
When the finger is passed over the surface little sand-like particles are felt, and the pus from the joint imparts the same sensation, as it frequently contains these particles, and little pieces of necrosed cartilage. The surface of the bone becomes more and more eroded, chiefly from friction, as may be recognized from the fact that the friction-lines are present, corresponding to the points of greatest pressure.
This attrition takes place on the articulating ends, and in the sockets of the joints, for instance, in the acetabulum, where it may reach such a degree that dislocation finally occurs, owing to the enlargement of the cavity. The neighboring parts are always involved in these inflammations; osteomyelitis (even with partial necrosis), periostitis, parostitis, etc., occur.
Chronic purulent arthritis may be recognized externally, by the enormous swelling of the entire joint (the knee and tarsus are most frequently affected). When a section is made through the diseased portion only a firm, white fibrous tissue (hence tumor albus) is seen, which is produced by chronic inflammation of the periarticular, intermuscular, and subcutaneous fibrous tissue, and which is often traversed by numerous sinuses lined with thick masses of granulations.
In the joint itself little or no pus may be found, but the synovial membrane is converted into a soft, thick, vascular mass of granulations, which frequently nearly fills the articular cavity. The bone presents similar changes, which, according to Rindfleisch, represent the primary affection. An osteoporosis results from a growth of the marrow, the bony trabeculae become diminished in size and partly necrosed, and the whole bone, the tarsal bones, for instance, becomes consequently so softened that a probe may be passed entirely through it with ease (fungous caries).
The cartilage is also secondarily affected by malacia and necrosis, for the granulations which spring from the bone attack it from below, while its upper surface is covered with granulations which grow from the synovial membrane and erode it from above. In such cases the granulations perforate the cartilage and spread out like a fungus upon the surface.
The cartilage also takes an independent part in the process, as the cartilage cells proliferate, the capsules become enlarged, and finally communicate with one another; a system of canals thus traverses the cartilage, and these canals constantly increase in size, owing to the disappearance of the intercellular substance, until the latter is entirely destroyed. These changes may be examined in suitable fresh preparations, but it is necessary to make vertical sections near the point where a perforation exists.
Tubercles are often found in the granulations arising from the bone, the synovial membrane, and the fistulas, and in consequence of their presence Köster, Rindfleisch, and others have been led to consider this affection as essentially tuberculous; a view which is not shared in by others, Virchow, for instance, as the tubercles are not always present.
One rare form of articular affection, arthritis urica., gout, still remains to be spoken of. The changes which take place in this affection are due to the presence of nodules (tophi) of varying size, composed of brittle, white, chalk-like masses, which are seated in the membrane of the joints, in the neighboring parts, and may protrude externally through the perforated skin.
These masses are composed of crystalline urate of soda and a very little fibrine. When the crystals are examined with a low power they appear to be acicular, but the use of high powers shows that they are rhombic prisms. The tophi also occur in the cartilage and bone, and may be very easily examined in sections made from the former. They are situated in the cellular cavities and in the intercellular substance.
The crystals appear black with transmitted, and white with reflected light. They disappear upon the addition of hydrochloric acid, and after a time whetstone crystals of pure uric acid are formed.
<Callout type="tip" title="Tip">Dislocations of the individual joints belong to surgery, and detailed information may be found in the text-books on this branch.</Callout>
The anatomical changes, however, which the articular surfaces (especially the head of the femur and the acetabulum) undergo in long-standing dislocations, may be alluded to. The head of the bone presents the changes already described as occurring in chronic arthritis deformans, the old socket disappears and a new one is formed, to which, however, the head of the femur is frequently firmly adherent.
<Callout type="important" title="Important">The examination of the bones has for a long time been confined to those cases in which some disturbance could be recognized from without, or was suspected from the clinical history.</Callout>
In all other cases, unless attention was called to the bones by appearances elsewhere, their examination has been omitted in order to avoid possible mutilation, and also from the difficulty necessarily to be encountered in displaying the marrow. The frequency of different affections of the bones, and especially of the marrow, is therefore greatly underestimated.
At the Pathological Institute in Berlin, for instance, metastatic tumors, especially cancer, disseminated tubercles, gummy osteomyelitis, etc., are not unfrequently found; the simple reason being that in every case of extensive tumor formation, constitutional syphilis, and miliary tuberculosis, the osseous system is always examined.
It is, of course, not possible to examine the whole skeleton, and the examination of one long bone usually suffices, at least in all general diseases, and also when no clinical symptom points elsewhere. The femur can be most conveniently removed, and should be sawed through longitudinally. The removal is best accomplished in the following manner, as it necessitates the least amount of mutilation. A deep incision, extending to the bone, is to be made in the direction of the large femoral vessels (which also frequently need to be examined), from Poupart's ligament to the middle third of the thigh. The ligamentum patellae is then cut through subcutaneously, and the knee-joint isolated by separating the skin from the upper part of the leg and the muscles from the lower part of the thigh. The capsular ligament is next cut through and the attachments to the femur separated from below upwards, till finally the capsular ligament of the hip-joint is stretched over the head of the bone, as is done in disarticulation, and the latter is enucleated.
By means of a vise and saw the bone is usually sawed through in the direction of its neck, and the sawdust removed from the surface by means of a stream of water and sponge. Whenever pathological changes are seen on the exterior of the bone the direction of the cut may, of course, be changed.
In the case of small children a very fine saw must be used, and it is often possible to divide the articular ends, which are frequently the only points of interest (in rickets, syphilis), with a stout cartilage knife. In examining the centre of ossification in the lower epiphysis of the thigh of new-born children, which is very important in medico-legal cases, the knee is to be strongly flexed and the ligamentum patellae cut through transversely. The patella is now
Key Takeaways
- Arthritis urica involves nodules of crystalline urate of soda in the cartilage and bone.
- Chronic arthritis can lead to malacia, fibrous degeneration, and erosion of the articular ends of bones.
- Periarticular abscesses and osteoporosis are common complications in chronic purulent arthritis.
Practical Tips
- Always consider the possibility of syphilis when examining joints for chronic inflammation.
- Regularly check for signs of malacia or necrosis, as these can indicate severe underlying conditions.
- Use microscopic examination to identify crystalline urate deposits in cases of suspected gout.
Warnings & Risks
- Be cautious with dislocations; they can lead to significant bone and joint damage if not treated properly.
- Avoid unnecessary examination of the entire skeleton, as it may cause mutilation.
- Perforations in joints are common but can be dangerous if left untreated.
Modern Application
While many of the techniques described in this chapter pertain to historical medical practices, the principles of diagnosing and treating joint inflammation remain relevant. Understanding these conditions can help modern survivalists prepare for potential injuries or illnesses that could arise during emergencies. The knowledge of identifying specific types of arthritis and their progression is crucial for effective treatment and management.
Frequently Asked Questions
Q: What are the key differences between acute and chronic purulent arthritis?
Acute purulent arthritis is rare, often occurring in cases with a special predisposition. It involves inflammation starting from the synovial membrane and quickly spreading to the cartilage and bone. Chronic purulent arthritis, on the other hand, leads to significant changes such as erosion of bones and formation of granulations, resulting in severe joint damage over time.
Q: How can one identify gout through pathological examination?
Gout can be identified by examining nodules (tophi) composed of crystalline urate of soda. These nodules are found in the membrane of joints, neighboring parts, and may protrude externally. Microscopic examination reveals rhombic prisms under high magnification.
Q: What are the common signs of chronic arthritis deformans?
Chronic arthritis deformans involves changes such as erosion of the articular ends of bones, formation of new sockets, and malacia or necrosis of cartilage. The head of the femur may become unrecognizable due to these processes.