under similar conditions to be very much diminished in size ; they are not, however, of a pale grayish-red, but of a light or dark brown color (brown atrophy). This condition is found (in teased preparations) to be due to the presence of small, irregular, brown pigment granules, as is the case with the similar change in the heart. There is also 2^. fatty atrophy (atrophy due to fatty degeneration), which corresponds with that occurring in the heart, and is characterized by its pale-yellow color and, when examined microscopically (teased preparations also), by the absence of transverse striations and the presence of glistening fat granules, which are insoluble in dilute caustic alkali. It is usually the result of an inflammatory process, and belongs under the head of parenchymatous myositis. It is supposed to be the cause of the so-called pernicious progressive muscular atrophy. Simple atrophy is by far the most common form, and appears constantly in old age and in all cachectic diseases (phthisis, cancer, etc.). It depends upon a simple diminution in size of the contractile substance, and differs from the 392 DIAGNOSIS IN PATHOLOGICAL ANATOMY. above-mentioned forms of atrophy in being more uniformly diffused.
<Callout type="warning" title="Fatty Atrophy Risks">This form can be a result of severe inflammation or infection, posing significant health risks.</Callout>
Haemorrhages into the muscles are moderate, small, or punctiform. The first form is usually traumatic in its origin, and the others occur in septic diseases, and especially in the vicinity of inflammatory processes, whether the latter are situated within the muscles or in the neighboring parts. When blood is effused, the muscular fibres are separated by the extravasated blood, and if the hemorrhage is extensive, they are so much injured as to become disintegrated, the resulting detritus being mixed with the blood.
The inflammations may be divided into those which involve the muscular tissue proper, and those which involve the interstitial tissue. (rt.) In the former (parenchymatous myositis) the well-known results, cloudy swelling and fatty degeneration, are presented, evident by the disappearance of the transverse striations, and the pale grayish or yellowish-red color and soft consistency of the muscle. This form occurs as a general affection in many infective diseases, the changes occurring in typhoid fever being the most familiar. In this disease the adductors of the thigh are most often affected, and may contain spots of actual softening. Circumscribed (local) forms may occur when the muscular substance takes part in inflammatory processes, for instance, in purulent interstitial inflammation, and especially in embolic affections (pyaemia, ulcerative endocarditis, etc.). A pathological change occurring in typhoid fever with true parenchymatous myositis has been described by Zenker as waxy (hyaline) degeneration, in which the contractile substance is converted into a homogeneous vitreous mass, the transverse striations completely disappearing. Later it becomes broken up transversely into rounded fragments, which are held together merely by the unaltered sarcolemma. These masses do not present the amyloid reaction, neither can they be looked upon as a specific typhoid alteration, as they appear in other diseases also, especially in those which THE MUSCLES OF THE EXTREMITIES. 893 are characterized by great muscular activity, for instance, in acute mania, and they may even be produced artificially.
<Callout type="important" title="Waxy Degeneration">This condition must not be confused with other forms of atrophy or degeneration.</Callout>
- New formations may result from tuberculosis and syphilis, both of which very rarely affect the muscles. Tuberculosis never occurs in the disseminated, miliary form, and very rarely as cheesy nodules or submiliary tubercles. The same may be said of the gummy tumors, which may be met with varying from the size of a hazel-nut to that of a walnut. Both they and the tubercles are found most frequently in the vicinity of similar pathological changes in the bones. Their diagnosis is made according to the rules already given in speaking of these tumors. The most common tumor is the sarcoma, which appears either as a primary growth or (by extension from bone, for instance) as a secondary form, and may become larger than a man's head. It is usually soft and composed of round cells, and is very often combined with other tumors, especially with myxoma (myxosarcoma of the thigh, etc.). The greater number of the muscular fibres at the periphery of the tumor become atrophied and destroyed, although the development of sarcomatous tissue from muscular substance has been described. The origin of these so-called muscular sarcomata is very rarely found in the muscles themselves, but they usually originate from the fasciae, ligaments, etc. Carcinoma never occurs primarily in the muscles, but secondary eruptions, which are in part accessory (filial nodules) and in part metastatic, are at times found; as a rule, they do not attain a very large size. The muscles take no active part in their development, but are frequently very much distorted, having rounded depressions upon their surface, etc. Cancer cells are sometimes found within the sarcolemma, although they have probably entered from without. These conditions may be very well seen even in fresh teased preparations.
All other tumors (fibromata, lipomata, myxomata, etc.) are less frequent, and easily diagnosed. 6. The parasites which occur in the muscles still remain to be considered. The most important of these are the trichinices, and they have already been spoken of in connection with the muscles of the neck and thorax. The Cysticercus cellulosoi is also frequently found in the muscles. It always lies between the separated muscular fibres, surrounded by a fibrous capsule, and is usually of the size of a pea or bean. Several specimens are usually found in different parts of the body, although solitary individuals are sometimes observed. When cysticerci have been found in the brain, they must always be sought for in the muscles. Echinococci are rare.
- THE JOINTS. The examination of the joints begins with that of the exterior, and the condition of the capsule is then to be especially noticed.
<Callout type="tip" title="Joint Capsule Examination">Always check for any alterations in the continuity of the capsule, as perforation may indicate a serious underlying issue.</Callout>
External Examination. The first point to be noticed is the degree of distention of the capsule, which determines at the same time the size of the cavity. This of course depends greatly upon the normal anatomical structure of the joints, since those provided with a loose elastic capsule (knee for instance), may undergo a greater amount of distention than others which have a very tense capsule (hip-joint, metatarsal joints, etc.). Partial or total obliteration of the cavity of the joints may occur as well as their distention; the two articular surfaces are then united by the formation of fibrous or bony tissue. When the latter occurs the term bony anchylosis is applied ; while the former is spoken of as fibrous anchylosis. The resulting immobility of the joint must not be confounded with pseudo-anchylosis, which depends upon a shrinking of the capsule, ligaments, fascias, etc., usually due to chronic inflammation. The form of the capsular ligament may become altered by projections (hernia) which may sometimes occur at certain portions of the wall.
<Callout type="warning" title="Pseudo-Anchylosis">Chronic inflammation can lead to pseudo-anchylosis, a condition that mimics true joint immobility but is reversible.</Callout>
The color of the external surface of the capsule is of but little importance, as it is usually the grayish-white of common fibrous tissue; the consistency, on the other hand, varies greatly, according as the cavity of the joint is filled with fluid (fluctuating) or solid material (firm). It is very important to notice any alterations in the continuity of the capsule. Perforation may be very often suspected when a fistulous opening is observed in the integument, and a probe should then be carefully inserted. Periarthritic abscesses may also occur, and their presence should likewise suggest the possibility of perforation. The cautious employment of the probe in these cases, is of great use.
Traumatic lacerations of the capsule differ from the perforations which result from ulceration. They are almost invariably caused by the protrusion of the articular head of the bone through a rent (dislocation), so that the external appearance of the joint is changed in the manner described in detail in every work on surgery. The term partial dislocation is applied when the two articular surfaces are carried out of their normal relative position while the capsule is intact. Dislocation may also result from the destruction of the capsule by ulceration as well as when it has been torn by violence, if the internal ligaments, or (in case of ball and socket joints, especially the hip) the cotyloid depression is destroyed.
<Callout type="important" title="Dislocation Diagnosis">Partial dislocations can be difficult to diagnose without a thorough examination.</Callout>
Internal Examination. When the external examination has been completed, during which the capsule is not to be cut into even if perforation exists, the capsule is to be opened as freely as possible; the directions for disarticulation are to be followed, and care must be taken to avoid injury to the surface of the joint. The contents are now to be examined.
- The Contents. Normal joints contain merely a few drops of synovia, which is a perfectly clear, viscid, yellow fluid; in the knee-joint, however, about a teaspoonful is usually found. When the contents of the joint are pathological, either a clear, colorless, serous fluid is present, or this fluid is mixed with fibrine or pus; the latter is often of an ichorous character, especially when the cavity of the joint communicates with the external air.
<Callout type="tip" title="Synovial Fluid Analysis">The presence of fibrine or pus in synovial fluid indicates a pathological condition.</Callout>
Loose bodies (corpora libera articulorum, mures articulares) sometimes occur in joints which present no other gross changes. These vary from the size of a millet-grain to that of an almond, are of a flat oval, irregular, or faceted shape, usually of a whitish color, and are either of a soft, cartilaginous, or bony consistency. When sections or teased fragments are examined microscopically, these bodies are found to be composed of fibrous tissue, frequently containing fat cells, or cartilage (hyaline and fibrocartilage), or bone. These tissues may also occur in combination.
The Internal Ligaments. The internal ligaments (ligamentum teres, ligamenta cruciata), which exist in certain joints, are next to be mentioned. It is necessary to cut them through, in order to separate the articular surfaces from each other for the purpose of thorough examination. They become involved in many inflammatory affections of the joints, and may consequently suppurate, become necrosed, or ruptured.
The Synovial Membrane. The synovial membrane, as is well known, is found only on the capsular ligament, and does not cover the articular surfaces. It may be thickened both by simple edematous swelling, and by an increase of its substance. Its color is pale-gray, but may become bright or dark-red from inflammatory distention of the blood-vessels, or from the presence of new-formed vessels. The synovial surface may be covered with pus, or more rarely with fibrinous false membrane; it may be smooth, or transformed into a granulating surface.
<Callout type="risk" title="Synovial Membrane Inflammation">Inflammation of the synovial membrane can lead to severe joint damage and pain.</Callout>
Hemorrhages and small spots from embolism (ulcerative endocarditis), are found within the membrane; also gray submiliary tubercles (secondary forms), which are frequently recognized with difficulty. The villi, which arise from the normal synovial membrane, especially near its attachment to the bones, become unusually prominent (growing papillary growths) in all chronic, inflammatory affections of the joints, and are very important in connection with the origin of loose bodies. They are composed of a soft, vascular, fibrous tissue, rich in cells, and frequently contain small cartilaginous nodules, which may assume a bony hardness from calcification. These villosities must not be confounded with arborescent lipomata (lipoma arborescens), which consist of the projection of papilliform growths of the subsynovial fat tissue into the cavity of the joint. These may also become separated from their attachment, and then form free bodies.
- The Articular Surfaces. In examining the articular surfaces the condition of the articular cartilage is to be noted, also the possible presence of any bony surface, and the appearance of the articular sockets.
<Callout type="important" title="Articular Cartilage Integrity">The integrity of the articular cartilage is crucial for joint health; its degradation can lead to severe pain and mobility issues.</Callout>
(a.) The articular cartilage is quite singular with respect to alterations in volume. At the point of greatest friction, namely, in the middle, atrophy takes place, while at the periphery the cartilage becomes hypertrophied; and these two changes may take place either singly or in combination. Enlargement appears in the form of excrescences, which sometimes form a continuous projection entirely around the bone. Atrophy may be more or less extreme, even leading to complete destruction of the cartilage. If this is not connected with a separation of portions of the cartilage, it is due to chondromalacia and superficial erosions, or to chondronecrosis with separation of the necrosed portions. These separated portions may then be found as yellowish-white plates floating in the contents (pus) of the joint. Their cartilaginous structure and the constant fatty degeneration of the cartilage cells may still be plainly recognized with the microscope. Granulations often project from the surface of the bone which has been thus uncovered, and form fungous masses spreading over the surface and the surrounding cartilage.
Fibrillation of the intercellular substance gives rise to a velvety appearance of the surface, and to an apparent enlargement of the cartilage. In fresh vertical sections, which may be easily made, the surface of the cartilage is seen to be composed of papillae (fibres) of varying size, and the cells are found to be greatly increased (formation of mother-capsules), but in a state of fatty degeneration. The fatty degenerated cells are set free by the disintegration of the intercellular substance, and may be found floating in the fluid of the joint.
Another pathological change which belongs under the head of atrophy, is the fibrous degeneration which cartilage undergoes in various affections, for instance, in adhesive arthritis, and in the cotyloid cavity after dislocation of the hip, etc., of long duration. An alteration in color accompanies all these changes of volume and shape. The translucent bluish-white appearance of normal cartilage becomes rather grayish-white or yellowish-white, both in fibrous degeneration and in necrosis. When the layer of cartilage is very thin, its color becomes modified by that of the bone beneath.
<Callout type="gear" title="Microscopic Examination">A high-quality microscope is essential for accurate diagnosis of joint pathologies.</Callout>
Key Takeaways
- Fatty atrophy and brown atrophy are common forms of muscular degeneration.
- Hemorrhages in muscles can lead to disintegration of muscle fibers, indicating severe trauma or infection.
- Synovial fluid analysis is crucial for diagnosing joint pathologies.
Practical Tips
- Regularly check the integrity of your joints and surrounding tissues for any signs of inflammation or damage.
- Maintain a healthy diet rich in anti-inflammatory foods to support overall musculoskeletal health.
- Stay physically active within safe limits to prevent atrophy and maintain joint mobility.
Warnings & Risks
- Be cautious when performing self-examinations, as some pathologies may require professional diagnosis.
- Avoid overexertion that could lead to traumatic injuries or exacerbate existing conditions.
- Do not ignore persistent pain or swelling in joints; seek medical attention if symptoms persist.
Modern Application
While the techniques described in this chapter are rooted in historical practices, they still offer valuable insights into diagnosing muscular and joint pathologies. Modern advancements have improved imaging technologies like MRI and CT scans, but understanding the basics of pathological anatomy remains crucial for effective diagnosis and treatment.
Frequently Asked Questions
Q: What is the difference between fatty atrophy and brown atrophy in muscles?
Fatty atrophy involves a pale-yellow color and glistening fat granules due to fatty degeneration, while brown atrophy presents as light or dark brown with small irregular pigment granules. Both are characterized by a reduction in muscle size but differ in their microscopic appearance.
Q: How can one identify the presence of synovial fluid in pathological conditions?
Pathological synovial fluid is typically clear, colorless, or mixed with fibrine and pus. The presence of these components indicates an underlying joint pathology such as inflammation or infection.
Q: What are the signs of pseudo-anchylosis in joints?
Pseudo-anchylosis is characterized by a shrinking of the capsule, ligaments, and fascias due to chronic inflammation. It mimics true joint immobility but can be distinguished through careful examination.
Q: How does chondromalacia affect articular cartilage?
Chondromalacia leads to atrophy of the articular cartilage, particularly in areas of high friction. It results in a velvety surface and can cause granulations and excrescences on the bone.
Q: What are the risks associated with dislocation of joints?
Dislocation can lead to severe pain, damage to surrounding tissues, and long-term joint instability. It may also result in chronic inflammation or pseudo-anchylosis if not properly treated.