Henry Ford Hosp Med Journal Vol 27, No 1, 1979

Arthritis: A Radiologic Overview

Gordon H. Beute, MD*

Fhediagnosisof is estabi ished bythe correlationof faces, alterations in the capsule or pericapsular clinical, laboratory and radiographic data. Some fundamen­ ligaments, and imbalance of action of opposing muscles tal aspects of radiographic evaluation will be reviewed. and tendons. The changes are often bilateral and symmetri­ cal. Secondary degenerative joint is uncommon Baseline radiographic study ofa patient with polyarthralgia except in the and , and when present it usually is should include films of involved and the contralateral not prominent. When the spine is involved, the cervical joints if they are presently asymptomatic. Generally, a region is most commonly affected. A typical finding is screening study for a peripheral arthritis should include a atlanto-axial subluxation. single view of the hands and , not only because these sites are frequently affected during the course of the disease, Juvenile usually involves the knees, but because differential radiographic features are more ankles and wrists. Less often affected are the hands, , apparent here than in other joints. The clinical presentation hips, feet, and cervical spine. Monoarticular may appropriately limit evaluation to a single joint, to the disease is more common in children than in adults. Ra­ appendicular skeleton or the axial skeleton. Serial studies diographic manifestations are similar to those in the adult are useful in assessing progression of the disease and but differ in several respects. Periosteal new bone is fre­ occasionally are helpful in differential diagnosis. quent. Bone length may be altered due to epiphyseal hypervascularity. Erosions and joint space narrowing are Because any single radiographic abnormality may lack seen later in the course of the disease, and occasionally diagnostic specificity, a comprehensive approach to the ankylosis and dislocation of large joints occur. The cervical films isessential. One should search for abnormal ities of soft spine is commonly involved, with a greater tendency for tissue, bone mineralization, cartilage space and malalign­ apophyseal joint ankylosis than in adult-onset disease. ment (Table 1).^

Rheumatoid arthritis in the adult (Figures 1 and 2) has a predilection for the extremities. Any synovial joint can be TABLE I* affected, but those most commonly involved of the upper extremity include metacarpophalangeal, proximal inter­ Soft Tissue Alignment Abnormalities phalangeal, intercarpal, radiocarpal and radioulnar joints. Quantity Flexion The distribution in the feet is analogous,^ though the inter­ Increased Hyperextension Focal or generalized Deviation phalangeal joints are less frequently afflicted. Synovial Decreased Subluxation , followed by pannus formation, results in Focal or generalized Joint Space periarticular soft tissue swelling, subarticular demineraliza- Density Widening tion, marginal and articularerosions and joint space narrow­ Calcification Effusion ing. Later changes include soft tissue atrophy, generalized Bone Mineralization Bone resorption osteoporosis, fibrous or bony ankylosis, and various typesof Decreased Cartilage overgrowth Fibrous deposition alignment abnormalities. Alignment abnormalities can re­ Generalized Focal Narrowing sult from cartilage destruction, resorption of articular sur­ Increased Cartilage loss Periosteal new bone Cysts Endosteal new bone Erosions * Department of Diagnostic Radiology, Henry Ford Hospital Fibrous or bony ankylosis Address reprint requests to Dr. Beute, Departmentof Diagnostic Radiology, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, Ml 48202 * Primarily applicable to hand and films

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Fig. 1. Rheumatoid arthritis (hands and wrists) Marked nodular soft tissue swelling about the wrists is present. Generalized osteoporosis, marked joint space narrowing, and extensive erosions are seen. Parlial carpal bone ankylosis, subchondral cysts in the radii, and mild subluxation of the right index finger (metacarpophalangeal joinl) are also preseni. Findings are symmetrical.

In degenerative joint disease (Figure 3), appendicular in­ and usually represent the site of earliest involvement. Root volvement characteristically includes the distal inter­ joints (hips and shoulders) and knees may also be affected.^ phalangeal joints of the hands, the first carpometacarpal joints of the wrists, first metacarpophalangeal joints of the In the sacroiliac joints, findings are always bilateral and feet, medial compartments of the knees, and the superior typically symmetrical.^ Early abnormalities include hazi­ aspects of the joints. Radiographic features include ness of subchondral bone, erosions, joint space widening nonuniform joint space narrowing, subchondral sclerosis, and reactive sclerosis. As the disease progresses, narrowing osteophytes, subarticular cysts or pseudocysts, normal min­ of the joint space and fibrous or bony ankylosis develop. eralization and sometimes malalignment. Asymmetry is In the spine, early involvement with common, while ankylosis is not. Similar findings occur in occurs at the thoracolumbar or lumbosacral junction. Ante­ the spine. The apophyseal joints can be involved, typically rior vertebral margins become straightened dueto osteitis, in the cervical and lumbar regions. In its primary and with a resulting square appearance of the vertebral body. secondary forms, degenerative joint disease is the most Syndesmophytes (vertical orientation of the reactive new common disorder of movable joints, and the radiographic bone as opposed to the transverse orientation of osteophytes features are usually distinctive. seen in degenerative joint disease) form laterally. Progres­ sive and universal syndesmophyte formation produces the Ankylosing spondylitis (Figures 4 and 5) primarily attacks classic "bamboo spine.Apophyseal joint changes range the axial skeleton. Both cartilaginous and synovial joints are from erosions and sclerosis to bony ankylosis. Less specific affected. The sacroiliac joints are almost always involved findings include osteoporosis, disc space narrowing, sub-

25 Arthritis: A Radiologic Overview

Fig. 3. Degenerative joint disease () Nonuniform medial joinl space narrowing, medial subchondral sclerosis, and subchondral cystic change are present. Nole the hypertrophic spurs al the medial tibial and femoral margins.

Fig. 2. Rheumatoid arthritis (knee) Osteoporosis, uniform joint space narrowing of medial and lateral frequent presence of periosteal new bone formation and compartments, and extensive subchondral cystic change are present. frequent lack of periarticular osteoporosis in Reiter's syn­ Note lack of secondary degenerative, hypertrophic change. drome are useful in differentiating it from rheumatoid arthritis. In the foot, the calcaneus may demonstrate fairly characteristic erosions, spur formation and periosteal new luxation, fractures, interspinous ligament ossification, and bone. With sacroiliac involvement, which can be either bone destruction by granulomas. unilateral or bilateral, the joint spaces are usually not In the root joints, the abnormalities are similar to those of obliterated.^ rheumatoid arthritis except for less osteoporosis and more reactive sclerosis. Occasionally, the end stage is bony In the spine, asymmetrical and nonmarginal syn­ desmophytes are seen. These findings are similarto those of ankylosis. Extraspinal bone-ligament-junction erosions and . bony proliferation produce a "whiskering" pattern ofthe bony cortex, most frequently at the iliac crests and ischial Psoriatic (Figure 6) has a predilection for the tuberosities. handsand, less commonly, the feet. It predominantly affects the distal interphalangeal joints, with asymmetric distribu­ Reiter's syndrome hasa predilection forthe sacroiliac joints tion. Fairly distinctive radiographic findings in the ex­ and the lower extremities, where involvement of heels and tremities include deformed nails, absence of periarticular toes is most common. In the upper extremities, the proximal osteoporosis, distal interphalangeal joint space widening interphalangeal joints are typically involved. The distribu­ due to bone resorption or fibrous deposition, periosteal tion is usually asymmetrical. Spinal involvement is reaction, and "pencil in cup" deformities (Figure 6). Occa­ infrequent. sionally, the radiographic abnormalities, including joint Distinguishing Reiter's syndrome from rheumatoid or disorganization, may be indistinguishable from rheumatoid psoriatic arthritis is sometimes difficult radiographically. The arthritis.

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ill-.

Fig. 4. Ankylosing spondylitis (lumbar spine and sacroiliac joints) Fig. 5. Ankylosing spondylitis (lumbar spine) Ankylosed sacroiliac joints and marginal, lateral syndesmophytes Lateral view illustrates loss of concavity of anterior vertebral body margin, (arrow) are seen. anterior and posterior spinal ligament ossification, disc space narrowing, osteoporosis and bony ankylosis of the apophyseal joints.

The axial skeleton is involved in fewer than halfof patients dominant in the cervical spine and can resemble rheu­ with psoriatic arthritis and usually when peripheral joint matoid arthritis. In contrast to ankylosing spondylitis, disease is present. The most prominent radiographic abnor­ "squaring" of vertebral bodies and apophyseal joint fusion mality in the spine is the presence of asymmetrical, non- are usually not seen.^ Sacroiliitis can be unilateral or bilat­ marginal syndesmophytes. Sometimes, the disease is eral, with changes similar to those of ankylosing spondyl itis.

27 Arthritis: A Radiologic Overview

Fig. 6. Psoriatic arthritis (feet) Asymmetrical involvement and predisposition for distal joints are typical. Terminal tuft and phalangeal resorption are seen, and characteristic "pencil in cup" deformity (arrow) is present. Minimal alignment deformity is noted. Periosteal new bone formalion, joint space widening, and bony ankylosis are nol seen.

Thecrystal deposition are and CPPD (calcium hyaline cartilage or fibrocartilage (). It is pyrophosphate dihydrate) deposition disease, the latter seen most often in the knees, wrists, hips, symphysis pubis more commonly known as pseudogout. The radiographic and intervertebral discs.^ Articular calcifications in syn­ findings, however, are quite dissimilar. ovium and the joint capsule may occur, as well as periar­ ticular calcification in tendons and soft tissues. Moreover, In gout (Figure 7), the hands and feet are most commonly the pseudogout syndrome can present radiographically with involved, with a predisposition for the great toe. Elbows, typical degenerative features, but in atypical joints for wrists and knees are also involved. Radiographic abnor­ degenerative joint disease, such as wrists, elbows and malities include asymmetrical softtissue swellingcaused by shoulders. Erosions are infrequent. Correlation between the tophi (subcutaneous accumulations of sodium monourate clinical manifestations and the radiographic abnormalities" crystals) that may calcify, and uniform joint space narrow­ is often poor. ing. Bone mineralization is normal. A particularly distinctive feature is juxtarticular location of erosions, which are most frequently affects the spine. The sacro­ caused by tophi that may stimulate the formation of "over­ il iac, symphysis pubis, sternoclavicular and knee joints are hanging edges."^ The erosion margins are well defined.^ also commonly affected. Organisms usually enter the joint by the hematogenous route or by extension from an os­ The pseudogout syndrome (Figure 8), which is charac­ teomyelitis. Radiologic features include softtissue swelling, terized by the deposition of calcium pyrophosphate dihydr­ cartilage destruction leading to joint space narrowing, and ate crystals, usually involves the knee. The most frequent subchondral bone destruction. Osteoporosis occurs radiographic abnormality is calcium deposition in articular promptly when joint destruction is present,^ followed by

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Fig. 8. CPPD deposition disease (knee) Chondrocalcinosis is present in bolh meniscal and articular cartilage.

space narrowing occurs late because the articular cartilage is spared initially. Neurotrophic arthropathy (Figure 10) results from repeated trauma as a consequence of losing pain sensation. The changes can be seen in numerous disease states, have a Fig. 7. Gout (foot) predilection for certain spinal levels, and correspondingly Note characteristic predilection for the great toe. Sofl tissue swelling and manifest with either upper or lower extremity involvement. intra-articular erosions are preseni. The great loe remains normally Two forms are seen. More common isthe hypertrophic form mineralized. Particularly distinguishing are the juxta-articular erosions, which usually involves the lower extremities. Radiographic with "overhanging edges" (arrow). findings include effusion, normal bone mineralization, joint space narrowing, fragmentation of articular surfaces, bony reactive sclerosis, with either an irregular articular surface or debris in the soft tissues, exuberant reactive marginal bone, bony ankylosis. If osteomyelitis is a component, sequestra­ dislocation, and total joint disorganization. The atrophic tion and periosteal new bone may develop. form is usually seen in the upper extremities and manifests In the spine, the disease originates in the intervertebral disc by effusion, osteoporosis, resorption of articular cartilage space. Early radiographic abnormalities include paraver­ and subchondral bone, and dislocation.^ In the neu­ tebral swelling, disc space narrowing, vertebral body end rotrophic spine, narrowed disc spaces, prominent os­ plate destruction, and collapse of the adjacent vertebral teophytes, fragmentation of vertebral bodies, and paraspinal bodies. Later changes include sclerosis, osteophytes and ossific debris are typical manifestations. ankylosis. Dystrophic paraspinal calcifications can also be Hemophilia (Figure 11) most commonly affects the knees, seen. elbows and ankles. Repeated hemorrhage in the joint results Tuberculous arthritis (Figure 9) also most commonly affects in effusions and chronic synovitis followed by marginal the spine, as well as the knees and hips. Radiologic man­ erosions, cartilage destruction with joint space narrowing, ifestations differ from those of septic arthritis in that os­ and secondary degenerative changes. Subchondral cysts, teoporosis appears early, as do marginal erosions. Joint caused either by degenerative changes or intraosseous

29 Arthritis: A Radiologic Overview

Fig. 9. Tuberculous spondylitis (thoracic spine) Disc space narrowing, wilh destruction of the adjacent vertebral body end plates and resultant kyphosis are seen. hemorrhage, can occur. A fairly distinctive sign is widening poses special problems. The soft tissues have limited value, ofthe intercondylar notch ofthe femur due to hemorrhage at and biochemical studies can rarely be obtained. In many of the insertion ofthe cruciate ligaments. Epiphyseal enlarge­ the specimens, only the spine, root joints or the pelvis are ment may develop in any affected joint. adequately preserved. Often, because specimens of the hands and feet have decayed, diagnostic specificity is Ochronosis (Figure 12) is the abnormal phenotype of alkap­ limited. An additional diagnostic constraint is imposed by tonuria, a metabolic disease. The spine is generally in­ the lack of serial films. For example, when evaluating an volved, with earliest changes seen in the lumbar region. end-stage arthritis, it is difficult to distinguish between Eventually, the entire spine is affected; the hips, shoulders primary, uncomplicated degenerative joint disease and and knees are less often involved. mixed arthritis. In perplexing situations, the best approach Radiographic findings in the spine include narrowed, cal­ may be to correlate radiographic information with the gross cified intervertebral discs, formation, os­ pathology. Hopefully, new biochemical techniques will be teoporosis and sometimes interspinous ligament able to confirm and supplement diagnostic possibilities calcification. Apophyseal joints are not involved. In the raised by radiographs and gross pathology. peripheral joints, ochronosis can produce effusions, joint Radiographic findings of many common arthritides have space narrowing, osteophytes, subchondral sclerosis, cal­ been discussed. The student of arthritis, ancient or modern, cified loose bodies and ligamentous ossification. Recently, should employ a systematic approach to the radiographs. Lee and Stenn^ have reported that the disc calcifications observed in an Egyptian mummy were the result of ochronosis. Acknowledgment Forthe physical anthropologist and paleopathologist, apply­ 1 thank Dr. William Reynolds for his thoughtful suggestions ing current radiographic knowledge to ancient specimens and J. King for her secretarial work.

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Fig. 10. Neurotrophic arthropathy, or Charcot's joint () Bone mineralization is normal, but joinl is extremely disorganized, wilh bony debris and dislocation as prominent fealures. Syringomyelia, which characteristically affecls the upper extremities, is the etiology.

Fig. 12. Ochronosis (lumbar spine) Lateral view demonstrates calcified intervertebral discs, narrowed disc spaces and eburnalive changes in the vertebral end plates.

References

1. Forrester DM, Brown JC, and Nesson JW: The Radiology of loint Disease, ed 2, Philadelphia, W,B, Saunders, 1978.

2. Greenfield GB: Radiology of Bone Diseases, ed 2. Philadelphia, J.B. Lippincott, 1975,

3. Martei W: The overhanging margin of bone. A roentgenologic man­ ifestation of gout. Radiology 91:755-756, 1968.

4. Resnick D: Calcium pyrophosphate dehydrale deposition disease: The pseudogout syndrome, chondrocalcinosis, and pyrophosphate arthro­ pathy, Princeton, NJ, Biomedia (Weekly Radiology Science Update) 38:1-4, 1977.

Fig. 11. Hemophilia (knee) 5. Lee SL and Stenn FF: Characterization of mummy bone ochronotic Overgrowth of the now-fused epiphyses, and secondary degenerative pigment. yAMA 240:136-139, 1978. changes, includ ing joint space narrowing, irregular articular surfaces, and 6. Murray RO and Jacobson HG:Jhe Radiology of Skeletal Disorders, ed 2. subchondral cystic change, are seen. New York, Churchill Livingstone, 1977.

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