Exercise: Arthritides

EXERCISE 7-4. ARTHRITIDES

7-12.The frontal pelvis view for Case 7-12 (Figure 7-34) shows all of the following features except

A.         A.loss of articular space.

B.         B.geode formation.

C.         C.juxtaarticular osteopenia.

D.         bony sclerosis.

7-13.The hands of the 45-year-old woman in Case 7-13 (Figure 7-35) show soft-tissue calcifications that are most consistent with a diagnosis of

A.         A.osteoarthritis.

B.         B.scleroderma.

C.         C.systemic lupus erythematosus (SLE).

D.         psoriasis.

7-14.The radiograph of the right hip in Case 7-14 (Figure7-36) is most compatible with

A.         A.osteoarthritis.

B.         B.gout.

C.         C.septic arthritis.

D.         scleroderma.

7-15. The imaging findings for Case 7-15, at the first metatarsal phalangeal joint (Figure 7-37), are most likely due to

A.   scleroderma.

B.   ankylosing spondylitis.

C.   gout.

D.   osteoarthritis.

7-16. The linear ossification connecting the cervical verte-bral bodies in Case 7-16 (Figure 7-38) are called

A.   osteophytes.

B.   erosions.

C.   soft-tissue swelling.

D.   syndesmophytes.

7-17. The “pencil-in-cup” deformity of the interphalangeal joint of the thumb in Case 7-17 (Figure 7-39) is most compatible with a diagnosis of

A.   psoriasis.

B.   gout.

C.   ankylosing spondylitis.

D.   SLE.

Radiologic Findings

7-12. The frontal radiograph of both hips in this case (Fig-ure 7-34) shows articular space narrowing, sclerosis, and subchondral cyst formation (also called geodes) bilaterally. There is no significant juxtaarticular os-teopenia (C is the correct answer to Question 7-12). The findings are most compatible with bilateral os-teoarthritis (OA) of the hips.

7-13. In this case (Figure 7-35), the most prominent fea-ture of this lady’s hand is soft-tissue calcification and

7-16. The lateral view of the cervical spine in Figure 7-38 shows prominent thin vertically oriented connec-tions between the anterior aspects of the vertebral bodies and fusion of the posterior elements of the spine. The thin vertically oriented ossifications are lo-cated anatomically in the outer layers of the annulus fibrosis and represent syndesmophytes that are asso-ciated with ankylosing spondylitis (D is the correct answer to Question 7-16).

7-17. Figure 7-39 shows a distinct “pencil-in-cup” erosion of the interphalangeal joint of the thumb and severe joint space loss of the distal interphalangeal (DIP) joints with bony ankylosis of the second, third, and fifth DIP joints. Fine periostitis is evident around some of the erosions. Theses findings are most com-patible with a diagnosis of psoriasis (A is the correct answer to Question 7-17).

Discussion 

Osteoarthrosis (Osteoarthritis)

The frontal view of the pelvis of Case 7-12 (Figure 7-34) shows the classic findings of osteoarthritis. These include joint space narrowing resulting in cartilage loss, subchondral cysts, and os-teophyte formation. The findings of osteoarthritis are similar inall joints. In the knee, the articular space narrowing typically in-volves the medial compartment initially (Figure 7-40) but may progress to involve the lateral and patellofemoral compart-ments. In the hands, the articular space narrowing typically in-volves the distal interphalangeal joints. Another classic “target area” of osteoarthritis in the hand is the first CMC (car-pometacarpal joint) and the STT (scaphotrapezo-trapezoidal) joint. There is a variant of osteoarthritis called erosive os-teoarthritis. Erosive osteoarthritis usually affects post-menopausal women and can be confused with rheumatoid arthritis. However, erosive arthritis usually affects the distal in-terphalangeal joints and exhibits predominately subchondral or central erosions as opposed to the marginal erosions seen in rheumatoid arthritis. These central or subchondral erosions have the classic “gull wing” appearance as shown at the proxi-mal interphalangeal joint of the third digit (Figure 7-41).

Connective Tissue Diseases and Seronegative Spondyloarthropathies

Generally, in the clinical setting of polyarticular stiffness and pain, conventional radiographs are used as the initial survey of the affected joints. These images target the most common regions of involvement and usually include films of the hands, wrists, pelvis, knee, feet, and ankles. The findings on these studies, coupled with the ESR value and other laboratory tests, should indicate whether a connective-tissue disorder is the cause of the arthropathy. Often patients will be tested for rheumatoid factor (discussed in the next paragraph). If this test is negative and the patient has symptoms involving the peripheral joints and spine, then a “seronegative spondy-loarthropathy” is considered.

Perhaps the most common and characteristic connective tissue disease producing arthritis is rheumatoid arthritis (RA). Females (especially middle-aged women) are more commonly affected by this disease than men. RA is thought to be a mal-function of the immune system, and patients with this disorder usually produce a measurable immune complex called rheuma-toid factor (RF). They also characteristically have an elevated ESR. The disease often progresses in a symmetrical fashion. The major initial pathologic process in RA is a synovitis that pro-duces periarticular osteopenia because of the associated hyper-emia. Later in the disease, synovial proliferation with pannus formation may then cause erosions in the juxtaarticular regions (the so-called bare areas). These erosions occur at the margins of the joint where the bony cortex and synovium contact each other without interposition of articular cartilage. The articular cartilage provides some protection from erosion in the early stages of the disease. Subsequently, the disease may progress to secondary degenerative changes and eventually to fibrous or bony ankylosis of the joint. In the wrist, the carpal bones will show osteopenia, carpal crowding, or subluxations. In fact, the ulnar styloid is often one of the first sites of erosions and “pen-ciling.” Juxtaarticular osteopenia is seen in the bones of the hands and wrists. Symmetric swelling at the proximal interpha-langeal joints of the hand is present, and the articular surfaces show erosions, especially at the metacarpophalangeal and prox-imal interphalangeal joints (Figure 7-42).

Systemic lupus erythematosus (SLE) is a connective-tis-sue disorder that can be seen in conjunction with other con-nective tissue diseases (the “overlap syndrome”). Patients with SLE may show profound osteopenia, including resorp-tion of the tufts, but it does not characteristically result in erosions. The typical appearance is of joint instability with multiple subluxations at the wrists and metacarpophalangeal joints. In fact, SLE is the most common cause of a nonerosive subluxing arthropathy (Figure 7-43). Subluxations also occur in RA, but the distinguishing factor is that the subluxations in RA are associated with the “bare area” erosions.

Scleroderma (also called progressive systemic sclerosis or PSS) is a disorder characterized by fibrosis and skin thicken-ing. Soft-tissue calcification is a prominent feature of this disorder. The major effects of this disease are not on the joints per se, but are secondary to the diffuse sclerosis with resultant joint stiffness for which the patient may seek treat-ment initially. About 10% of patients with PSS have synovi-tis that is indistinguishable from RA at presentation, and many of these patients eventually develop Raynaud’s phe-nomenon. The typical imaging findings are periarticular cal-cification and resorption of the terminal phalangeal tufts (acroosteolysis). Scleroderma may also be associated with other connective disorders such as rheumatoid arthritis and SLE in the same individual.

Psoriasis, Reiter’s disease, ankylosing spondylitis, and in-flammatory bowel disease comprise the major seronegative spondyloarthropathies. Psoriasis is a connective tissue disor-der that primarily affects the skin. However, about 15% of pa-tients with psoriasis develop bone and joint changes, and these findings may be the initial manifestations of the disease. Radiographic findings of psoriasis include periosteal reaction(periostitis) and/or focal cortical thickening in the digits. The earliest manifestation of the disease is juxtaarticular osteopenia that is less profound than in RA. The disease may then progress to show erosions at the articular sur-faces. The distribution of these findings in psoriasis is mainly the distal interphalangeal joints, unlike the findings in patients with RA, which are predominately in the proxi-mal interphalangeal joints, metacarpophalangeal joints, and carpus. The “pencil-in-cup” erosion seen in Figure 7-39 is typical of psoriasis. Patients with psoriasis and other seronegative spondyloarthropathies also develop ab-normalities of the spine and sacroiliac joints (hence, the term spondyloarthropathy).

Reiter’s disease is a postinfective disorder of the immune system that is characterized by the triad of non-gonococcal urethritis, conjunctivitis/iritis, and arthritis. Seen most fre-quently in male patients, Reiter’s disease was originally thought to be caused by Chlamydia, but other organisms, in-cluding Escherichia coli and Salmonella organisms, have also been implicated. The imaging findings of Reiter’s disease are often indistinguishable from those of psoriatic arthritis ex-cept that Reiter’s disease most commonly affects the feet and psoriasis most commonly affects the hands. Both diseases show periostitis, erosions, and enthesopathic changes. An en-thesis is an area of attachment of a ligament or tendon to bone by the perforating fibers of Sharpey. An enthesopathy is, therefore, an abnormality at this site and is seen on the radi-ograph as bony excrescences in these areas. A typical example of enthesopathy in Reiter’s disease is the bony excrescence on the inferior aspect of the calcaneus, which develops at the site of attachment of the plantar fascia and the short flexors in the foot (Figure 7-44).

Ankylosing spondylitis (AS) is a rheumatic disease causing arthritis of the spine and sacroiliac joints and can cause in-flammation of the eyes, lungs, and heart valve. The typical clin-ical scenario is intermittent back pain that occurs throughout life. The pain may progress to severe chronic disease attacking the spine, peripheral joints, and other organs resulting in marked loss of motion and deformity over time. The cause of AS is not known, but most of the spondyloarthritides share a common genetic marker called the HLA-B27 antigen. The dis-ease usually presents in the adolescent and young adults and is most common in Native Americans.

Figure 7-38 shows the typical features of AS in the cervi-cal spine. The thin vertically oriented ossifications connect-ing the vertebral bodies, syndesmophytes, are anatomically located in the outer layers of the annulus fibrosis. Also typical in this case is the fusion of the posterior elements. In fact, the classic appearance of AS is the “bamboo spine” (Figure 7-45). This appearance is caused by fusion of all the synovial joints of the spine and predisposes the patient to the development of fractures (insufficiency type fractures). This insufficiency fracture (which may lead to a “pseudoarthrosis”) is a well-documented complication of ankylosing spondylitis.

The mainstay of treatment for AS is nonsteroidal anti-inflammatory medication to control pain. However, some patients with severe disease may be given methotrexate.

Septic Arthritis

Septic arthritis is usually blood-borne (hematogenous) and is most commonly monoarticular (that is, involving only one joint at any time). A common cause of septic arthritis in the adult is Staphylococcus aureus, although other infective agents including Streptococcus, Gonococcus, and other gram-negative organisms may also be encountered. Streptococcus and gram-negative organisms are particularly important in the pediatric age group. Also, tuberculosis has been recently encoun-tered with greater frequency, especially in patients who are immunocompromised.

The radiographic examination of the patient in Case 7-14 (Figure 7-36) provides general anatomic information, helps to determine whether further imaging is necessary, and aids in deciding whether further intervention is appropriate. Her physicians were very worried about septic arthritis in this clinical setting of previous renal transplant (ie, relatively im-munocompromised), and a hip aspiration was requested. Twenty milliliters of bloodstained turbid fluid was aspirated and was sent to the microbiology laboratory for Gram’s stain, culture, and sensitivity studies. The cultures grew Staphylo-coccus aureus, a common pathogen in septic arthritis.

Figure 7-36 shows the classic radiographic findings of sep-tic arthritis and osteomyelitis. These include articular space narrowing, erosion of bone on both sides of the joint, and sclerosis. An effusion is typically present and can be identified by ultrasound or MR imaging. In addition, MR imaging can be useful if abscesses are suspected in the adjacent soft tissues. Septic joints will exhibit increased uptake on bone scan be-cause of the marked hyperemia and bony proliferation.

Crystal Deposition Diseases

Gout, a disorder more common in middle-aged men, is an inflammatory arthritis caused by abnormal deposition of urates (called tophi) in the soft tissues and cartilage. These deposits cause episodic joint inflammation and are associ-ated with pain and disability. In the earlier stages of the dis-ease, radiographs of the bone and joints may be normal except for soft-tissue swelling and in some instances soft-tissue calcification. The initial classic clinical presentation of gout is podagra, an acute inflammation of a joint, often the first metatarsal phalangeal joint (Figure 7-37). At presenta-tion, the patient will have severe joint pain, and the overlying soft tissues will be swollen and red. With repeated attacks over years, bony erosions with “overhanging edges” (or over-hanging margins) may develop adjacent to the joint but not within the joint. When the patient is severely incapacitated by pain and not moving the joint, “disuse” osteopenia can be seen at radiography. The typical areas to screen for gout are the first metatarsophalangeal joint, the heel, the back of the elbow joint (olecranon fossa), and the hands and wrists. Screening for elevated serum levels of uric acid and joint as-piration are the best ways to confirm the clinical suspicion of gout after obtaining conventional radiographs. The joint as-pirate will show birefringent uric acid crystals in the synovial fluid on polarized light microscopy.

Calcium pyrophosphate dehydrate crystal deposition (CPPD) disease is another common crystal deposition joint disorders. In CPPD disease, there is calcification in the fibrocartilage and hyaline articular cartilage (so-called chon-drocalcinosis). The most common association with chondro-calcinosis is aging, although it may also be seen in pseudogout (CPPD disease), gout, ochronosis, hemochromatosis, and hy-perparathyroidism. This finding is most commonly seen in the wrist, symphysis pubis, or knee. So, if one suspects a patient of having CPPD, radiographs of the pelvis, wrist, and knees would be a good start at screening for it. The presence of calci-fication alone is not diagnostic of CPPD, however. The clinical syndrome of pain from the presence of abnormal cartilage cal-cification is referred to as the CPPD syndrome, and symptoms may be provoked by various stresses (eg, surgical procedures). Confirmation of the diagnosis may be obtained by identifica-tion of calcium pyrophosphate crystals from synovial fluid ob-tained via percutaneous aspiration of the affected joint.