collagen vascular disease
Post on 10-Jul-2016
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The collagen vascular diseases (connective tissue diseases) are a group of diseases that have multiple, varied systemic manifestations. Articular symptoms play a minor role in the total clinical picture and usually produce little in the way of radiographic change in the joint. Although each disease has distinct features, there is a tendency toward overlap among the diseases. The diseases to be discussed are systemic lupus erythematosus, scleroderma, dermatomyositis, polyarteritis nodosa, and mixed connective tissue disease.
SYSTEMIC LUPUS ERYTHEMATOSUS
Systemic lupus erythematous (SLE) is the most common of the collagen vascular diseases. In this disease, articular symptoms are present in 75 to 90 percent of patients. The radiographic changes are:
1. Soft tissue swelling2. Juxta-articular osteoporosis3. Subluxations and dislocations4. Absence of erosions5. Absence of joint space loss6. Calcification7. Osteonecrosis8. Bilateral and symmetrical distribution9. Distribution in hand and wrist, hip, knee, and shoulder
The radiographic changes divide into three different categories: (1) deforming nonerosive arthri-tis, (2) osteonecrosis, and (3) calcification of soft tissue.
Deforming Nonerosive Arthritis
A deforming nonerosive arthritis is seen most commonly in the hands and wrists (Fig.20-1). Early in the course of the disease, soft tissue swelling is seen, with eventual soft tissue atrophy. Juxta-articular osteoporosis is present that eventually becomes diffuse osteoporosis. When not distorted by subluxation or dislocation, the joint space appears preserved. Subluxation or dislocation without erosive disease is the hallmark of SLE. The subluxations are usually easily reducible.
Collagen Vascular Diseases (Connective Tissue Diseases)
346 Radiographic Changes Observed in a Specif ic Articular Disease
FIGURE 20-1. Posteroanterior (PA) view of both hands in a patient with SLE. Osteoporosis is present. Severe subluxations of all joints are present. There is no evidence of erosive disease. This is the classical deforming nonerosive arthritis of lupus.
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Deformities may not be detected on the routine PA radiograph in which the technician has carefully positioned the digits for optimum imaging; however, on the Nrgaard view, in which the fingers are not positioned rigidly, the subluxations become apparent (Fig.20-2). A similar deform-ing nonerosive arthritis may involve the knee or the shoulder, but it is more difficult to image radiographically.
FIGURE 20-2. A, PA view of the hand in a patient with SLE. Juxta-articular osteoporosis is present. There is minimal subluxation of the MCP and PIP joints of the index finger. B, View of the same hand in the Nrgaard position. The fingers have not been rigidly positioned by the technician; therefore, severe sublux-ations of the MCP joints become apparent.
348 Radiographic Changes Observed in a Specif ic Articular Disease
Osteonecrosis is said to occur in 6 to 40 percent of patients with SLE. Although most of these patients are on steroids, it is known that SLE causes osteonecrosis even in the absence of steroid treatment. The patient with SLE with a significant vasculitic component who is being treated with steroids is extremely prone to osteonecrosis. The femoral heads, the humeral heads, the femoral con-dyles, the tibial plateaus, and the tali are the most common sites of osteonecrosis in SLE (Fig.20-3); however, it has also been seen in the lunates, the scaphoids, and the metacarpal and metatarsal heads (Fig.20-4). It usually occurs bilaterally and asymmetrically.
FIGURE 20-3. AP view of both knees in a patient with lupus. Osteonecrosis is observed in both lateral femoral condyles.
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FIGURE 20-4. AP view of MTP joints in a patient with lupus. There is osteonecrosis present in the heads of the second and third metatarsals (arrows).
350 Radiographic Changes Observed in a Specif ic Articular Disease
The radiographic findings are those observed in osteonecrosis of any etiology. Dead bone does not change radiographically. The radiographic changes observed are those of repair. The initial bone loss or osteoporosis in the repair process may not be appreciated radiographically. The first radiographic change may be increased smudgy density, which represents either dead bone that appears dense in comparison to the surrounding osteoporosis or reparative bone (Fig.20-5). One may see a combination of osteoporosis and osteosclerosis. Advanced osteonecrosis is present when a subchondral lucency is seen (Fig.20-6). The lucency is created by vacuum introduced between a distracted subchondral frag-ment and the remaining femoral head. It represents impending collapse of the articular segment into the underlying bone, if it has not already occurred. Once the articular surface has been deformed, the actual joint undergoes secondary osteoarthritic changes.
FIGURE 20-5. AP view of both hips in a patient with lupus. The right hip is normal. Increased smudgy den-sity is observed in the left femoral head. This is an early radiographic change of osteonecrosis.
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Calcification may be present in the subcutaneous tissue in patients with SLE. It is usually linear and streaky in its appearance. There is no definite association of this calcification with the deforming nonerosive arthritis or with the osteonecrosis. If seen alone, this calcification is difficult to differen-tiate from that of other collagen vascular diseases.
FIGURE 20-6. Specimen radiograph of a femoral head with advanced osteonecrosis. (The specimen was surgically removed from a patient with SLE.) There is a combination of osteoporosis and osteosclerosis present. A large subchondral lucency or vacuum separates the detached subchondral fragment from the underlying collapsed bone.
352 Radiographic Changes Observed in a Specif ic Articular Disease
Forty-six percent of patients with scleroderma have articular symptoms. The radiographic changes appear to be limited to the hands and wrists. The radiographic changes are:
1. Resorption of soft tissue of the fingertip2. Subcutaneous calcification3. Erosion of the distal tuft4. Acrosclerosis
The first visible radiographic change is the resorption of the soft tissue of the fingertip. In the normal finger, the soft tissues distal to the distal tuft usually measure 20 percent of the transverse dimension of the base of the distal phalanx (Fig.20-7). This may or may not be accompanied by amorphous calcification (Fig.20-8). Of the fingers involved, 40 to 80 percent have erosion of the distal tuft (acroosteolysis). It begins on the palmar aspect of the tuft and may progress to resorb the entire distal tuft (Fig.20-9). Erosive disease can be seen in up to 25 percent of patients most com-monly in the interphalangeal (IP) joints or the first carpometacarpal joint (Fig.20-10).
FIGURE 20-7. PA view of normal index finger (A) shows normal soft tissue (short arrow) distal to the distal tuft measuring more than 20 percent of the width of the distal phalanx (long arrow). PA view of index finger in patient with scleroderma (B) shows marked atrophy of distal soft tissues.
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FIGURE 20-8. PA view of three digits in patient with scleroderma. There is amorphous calcification in the soft tissues of the distal phalanges. There are accompanying erosive changes of the distal tuft.
FIGURE 20-9. PA view of three digits in patient with scleroderma. There is amorphous calcification present in the soft tissues. Early resorption of the distal tuft is seen in the middle digit (arrow).
FIGURE 20-10. PA view of the hand in patient with scleroderma. Erosions and joint space loss are seen in the second MCP joint (arrows). There is pancarpal joint space loss with sclerosis and collapse of the lunate sec-ondary to avascular necrosis. There is marked distal soft tissue atrophy of the second and third digits and acro-osteolysis of the thumb distal phalanx.
354 Radiographic Changes Observed in a Specif ic Articular Disease
In patients with dermatomyositis, the radiographic abnormality most commonly observed is soft tissue calcification (Fig.20-11). This is present more often in children than in adults. It is usually identified along intermuscular fascial planes, but it may be present around joints or subcutaneously. If articular symptoms are present, then there are usually no radiographic findings around the joint. Sometimes transient osteoporosis may be seen, and there have been occasional reports of distal tuft resorption similar to that seen in scleroderma.
FIGURE 20-11. AP view of the thigh in dermatomy-ositis. Calcification is seen along intermuscular fascial planes as well as in subcutaneous tissue.
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The only radiographic change reported in polyarteritis nodosa is periosteal new bone forma-tion. This has been limited primarily to the tibia and fibula and has appeared in a symmetrical fashion.
MIXED CONNECTIVE TISSUE DISEASE
Mixed connective tissue disease (MCTD) was originally defined in a patient having a combina-tion of SLE and scleroderma. Today, a patient with MCTD may have features of SLE, sclero-derma, and rheumatoid arthritis. The disease entity is defined serologically. Radiographically, the patient may have features of all three diseases involving primar