Radiographic Evaluation of Arthritis ... · eral shoulder joints). Repetitive intraarticular hemorrhage, asseen with hemophilia, may cause car-tilage destruction and radiographic

Radiographic Evaluation ofArthritis: Degenerative Joint Diseaseand Variations1

Jon A. Jacobson, MDGandikota Girish, MDYebin Jiang, MD, PhDBrian J. Sabb, DO

In the presence of joint space narrowing, it is important todifferentiate inflammatory from degenerative conditions.The presence of osteophytes, bone sclerosis, and subchon-dral cysts and the absence of inflammatory features suchas erosions suggest osteoarthritis. Typical osteoarthritisinvolves specific joints at a particular patient age. Whenosteoarthritis involves an atypical joint, occurs at an earlyage, or has an unusual radiographic appearance, thenother causes for cartilage destruction should be consid-ered, such as trauma, crystal deposition, neuropathicjoint, and hemophilia. There are several types of arthritis,such as juvenile chronic arthritis and gouty arthritis, thatmay have a variable appearance compared with that ofother common inflammatory arthritides.

� RSNA, 2008

1 From the Department of Radiology, University of Michi-gan Medical Center, 1500 E Medical Center Dr,TC-2910L, Ann Arbor, MI 48109-0326. Received Decem-ber 11, 2006; revision requested February 7, 2007; revi-sion received July 25; accepted September 12; final ver-sion accepted November 7; final review by J.A.J. April20, 2008. Address correspondence to J.A.J. (e-mail:[email protected] ).

� RSNA, 2008

REVIEWS

ANDCOM

MENTARY

�REVIEW

FORRESIDENTS

Radiology: Volume 248: Number 3—September 2008 737

Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.

Radiography is commonly used inthe evaluation for arthritis. A ba-sic algorithm based on radio-

graphic findings can be followed toreach a final and usually correct diagno-sis (Fig 1). While it is impossible toinclude all forms of arthritis with theirvariations into one scheme, this algo-rithm can be used as a framework forevaluation, as it encompasses the mostfrequent radiographic features of com-mon arthritides.

The starting point for the algorithmis joint space narrowing. The next stepis to determine if the joint process isinflammatory or degenerative. While aninflammatory condition is suggested byosteopenia and soft-tissue swelling, it isthe presence of bone erosions that is thecharacteristic finding of inflammation.Early erosions will appear as disconti-nuities of the thin, white, subchondralbone plate, commonly involving thejoint margins (Fig 2). Uniform jointspace narrowing may also be present. Incontrast, a degenerative cause of jointspace narrowing is characterized by os-teophytes; bone sclerosis; subchondralcysts, or geodes; asymmetric joint spacenarrowing; and lack of inflammatoryfeatures such as bone erosions (Fig 3).

In part 1 of this review (1), commoninflammatory arthritides were dis-cussed. The present review will first fo-cus on degenerative joint diseases,which include typical osteoarthritis aswell as less typical forms of osteoarthri-tis, as may be seen with trauma, crystaldeposition disease, and hemophilia. Fi-nally, variations from the algorithm willbe discussed, including conditions suchas juvenile chronic arthritis, inflamma-tory osteoarthritis, and gouty arthritis.

Degenerative Joint Disease

A degenerative process is suspectedwhen joint space narrowing, osteophyteformation, bone sclerosis, and subchon-dral cysts are seen in the absence ofinflammatory changes (Fig 3). Whendegenerative joint disease involves a sy-novial articulation, the term osteoar-thritis or osteoarthrosis is used. Com-monly, joint space narrowing from osteoar-thritis is associated with osteophyteformation, especially in the knee (2).With the hips and knees, a weight-bearing radiograph will improve detec-tion of early joint space narrowing. Thefinding of marginal osteophytes is typi-cally used to detect osteoarthritis, whilethe findings of joint space narrowing,bone sclerosis, and subchondral cystsare used to assess severity (2). As thejoint space narrows, the osteophytesbecome larger, bone sclerosis in-creases, and subchondral cyst, or ge-ode, formation may be seen. When os-teoarthritis is identified at radiography,it is important to consider the joint in-volved, the age of the patient, and theradiographic appearance as the nextstep in the algorithm.

Typical OsteoarthritisOsteoarthritis is typically the result ofarticular cartilage damage and wear andtear from repetitive microtrauma thatoccurs throughout life, although ge-netic, hereditary, nutritional, meta-bolic, preexisting articular disease, andbody habitus factors may contribute insome cases. This process tends to in-volve specific joints during specific de-cades of a person’s life and depends inpart on the patient’s body habitus and

level of physical activity. For example,one of the first joints that may demon-strate osteoarthritis is the acromiocla-vicular joint, where minimal osteophyteformation may be seen in the 4th de-cade of life and beyond, owing to thestresses that occur at this joint (Fig 4).Another site of typical osteoarthritis isthe first carpometacarpal joint, oftenbeginning after the 5th decade of life,owing in part to stresses related to con-stant use of opposing thumbs or jointlaxity (Fig 5a) (3). Osteoarthritis alsocharacteristically involves the interpha-langeal joints of the hands after the 4thor 5th decades of life; this is related inpart to degree of use and overuse (Fig5b) (4).

Involvement of the metacarpopha-langeal joints is not infrequently associ-ated with osteoarthritis of the interpha-langeal joints, although this type of in-volvement is usually of lesser severity.Unlike in larger joints, joint space nar-rowing of the interphalangeal and meta-carpophalangeal joints in osteoarthritismay be symmetric. Osteoarthritis of thefirst metatarsophalangeal joint is com-mon beginning in the 5th decade of life(Fig 6) and may be associated with hal-lux valgus deformity.

As a person ages, osteoarthritis isidentified involving the knee joints andhip joints, beginning after the 4th or 5thdecade of life (4). With regard to theknee joints, joint space narrowing istypically asymmetric and most com-monly involves the medial femorotibialcompartment, possibly with the patel-lofemoral compartment (Fig 7) (5).Similarly, hip joint space narrowing isasymmetric, with superior migration ofthe femoral head more common thanmedial migration (Fig 8) (6). Underlyingacetabular dysplasia is associated withsuperolateral migration. With early hiposteoarthrosis, a frog leg view will often

Published online10.1148/radiol.2483062112

Radiology 2008; 248:737–747

Abbreviation:CPPD � calcium pyrophosphate dihydrate

Authors stated no financial relationship to disclose.

Essentials

� With joint space narrowing, it isimportant to differentiate inflam-matory from degenerative causes.

� Typical osteoarthritis involvesspecific joints at a particular pa-tient age.

� Osteoarthritis of an atypical joint,at an early age, or with an atypi-cal appearance suggests other lesscommon causes for cartilage de-struction.

� An atypical appearance of osteo-arthritis can be due to trauma,crystal deposition disease, neuro-pathic joint, and hemophilia.

� Juvenile chronic arthritis andgouty arthritis are two types ofarthritis that have an appearancethat is different from that of othercommon inflammatory arthrit-ides.

REVIEW FOR RESIDENTS: Radiographic Evaluation of Arthritis Jacobson et al

738 Radiology: Volume 248: Number 3—September 2008

reveal a rim or collar of osteophytesthat may be more difficult to visualize onan anteroposterior radiograph.

The sequence of osteoarthritis de-scribed above can be somewhat vari-able. Regardless, when osteoarthritis isidentified, it is important to considerwhich joint is involved, the severity ofthe radiographic changes, the distribu-tion of osteoarthritis, and the age of thepatient to make the distinction betweentypical and atypical osteoarthritis.

Atypical OsteoarthritisIf radiographic findings of osteoarthritisare identified but the involved joint isnot one commonly affected by osteoar-thritis, the severity of the findings areexcessive or unusual, or the age of thepatient is unusual, then other less com-mon causes for cartilage damage andosteoarthritis should be considered.Possible causes for this atypical appear-ance of osteoarthritis include trauma,crystal deposition disease, neuropathicjoint, and hemophilia. Other possiblecauses include congenital and develop-mental anomalies, such as dysplasia,that disrupt normal biomechanics.

Trauma is the most common causefor atypical osteoarthritis. This may bea sequela of (a) a prior traumatic eventthat causes cartilage damage and accel-erated osteoarthritis or (b) an unusualand excessive repetitive injury, whichmay be seen in an athlete or may beoccupational. For example, a remoteathletic injury may produce an acceler-ated appearance of knee or hip osteoar-throsis. The clue for diagnosis is therelatively young age of the patient, in-volvement of an atypical joint (Fig 9),marked unilateral asymmetry of lowerextremity joint involvement, or unusualseverity. Another example of atypicalosteoarthritis is due to excess occupa-tional stresses and repetitive injury thatis atypical because of patient’s age andinvolvement of an unusual joint, such asthe elbow.

Calcium pyrophosphate dihydrate(CPPD) crystal deposition disease maycause chondrocalcinosis and calcifica-tion of the synovium, joint capsule, ten-dons, and ligaments. In addition, CPPDcrystal deposition disease may cause an

arthropathy that can appear as atypicalosteoarthritis. Although radiographicfindings of CPPD appear somewhat sim-ilar to those of osteoarthritis, they areatypical because of joint distribution,extensive subchondral cyst formation,and associated calcium deposition, in-cluding chondrocalcinosis. For exam-ple, CPPD arthropathy characteristi-

cally involves the radiocarpal joint ofthe wrist and the second and thirdmetacarpophalangeal joints of thehands (Fig 10) (6). Chondrocalcinosisof the triangular fibrocartilage is com-mon, although calcium deposition in theintrinsic carpal ligaments (in particularthe lunotriquetral ligament) and jointcapsules is also seen (7). In the knee,

Figure 1

Figure 1: Flow chart shows approach to radiographic evaluation of arthritis. Algorithm begins with jointspace narrowing and initially uses differentiation between inflammatory and degenerative findings to reach thefinal diagnosis. (Reprinted, with permission, from reference 1.)

Figure 2

Figure 2: Inflammatory arthritis (rheumatoidarthritis). Posteroanterior radiograph shows dis-continuity of bone cortex, representing marginalerosions (arrows).

Figure 3

Figure 3: Osteoarthritis. Posteroanterior radio-graph shows interphalangeal joint space narrow-ing, subchondral sclerosis, and osteophyte forma-tion (arrows).



which is the joint most commonly af-fected by CPPD crystal deposition dis-ease, disproportionate patellofemoraldegenerative change is characteristic(Fig 11) and is associated with chondro-calcinosis, which affects the fibrocarti-lage menisci and hyaline cartilage (8).Calcium deposition in the gastrocne-mius tendon origin is another findingseen with CPPD crystal deposition dis-ease in the knees (Fig 11) (8). Othersites of chondrocalcinosis include thepubic symphysis and the hip labrum (9).

Because the finding of chondrocalci-nosis alone is nonspecific (other causesinclude hemochromatosis and hyper-parathyroidism, among others), it is thecoexistent finding of CPPD arthropathythat suggests CPPD crystal depositiondisease as the cause. It is important toconsider the diagnosis of hemochroma-tosis when the radiographic findings ofCPPD are identified, as there is substan-tial overlap in their radiographic find-ings. In hemochromatosis, more exten-sive involvement of the second throughfifth metacarpophalangeal joints hasbeen described, and metacarpal radialhooklike or drooping osteophytes aremore common (Fig 12) (9).

Another cause for an atypical ap-pearance of osteoarthritis includes anearly neuropathic joint. In this situation,the loss of feedback mechanisms of sen-sation and proprioception leads to jointinstability and degenerative changesduring daily activities. While the char-acteristic findings of a neuropathicjoint—namely sclerosis, fragmentation,and subluxation—are obvious in thelater stages of this process, the earlychanges of a neuropathic joint will oftenappear as atypical osteoarthritis (10).The primary clue to the diagnosis of anearly neuropathic joint is the distribu-tion of radiographic changes, which de-

pends on the cause of the neuropathy.For example, involvement of the mid-foot is characteristic with diabetes mel-litus, where findings of joint space nar-rowing, bone sclerosis, and osteophytesare seen (Fig 13). The findings of coex-isting arterial calcifications further sug-gest the diagnosis of neuropathic joint,and correlation with patient history isimportant. Other causes of neuropathicjoint include syphilis or tabes dorsalis(involving the lower extremity jointsand spine) and syrinx (involving bilat-eral shoulder joints).

Repetitive intraarticular hemorrhage,as seen with hemophilia, may cause car-tilage destruction and radiographic fea-tures of atypical osteoarthritis (Fig 14).Although bone erosions due to second-ary synovial inflammation may be seen,often the osteophytes, bone sclerosis,and subchondral cysts are most appar-ent. The combination of bone erosionsand osteophyte formation creates an ir-regular appearance to the articular sur-face. When one sees these degenerativechanges, it is the possible atypical jointdistribution and young age that are incontrast to characteristics of typical os-teoarthritis (Fig 15). Other features ofhemophilia include somewhat moresymmetric joint space loss, the pres-ence of excessive subchondral cyst for-

Figure 4

Figure 4: Osteoarthritis. Anteroposterior acro-mioclavicular joint radiograph shows joint spacenarrowing, sclerosis, and osteophyte formationinvolving the acromioclavicular joint (arrow).

Figure 5

Figure 5: Osteoarthritis. (a) Posteroanterior and (b) oblique hand radiographs show joint space narrowing,sclerosis, and osteophyte formation of (a) first carpometacarpal (arrow) and (b) interphalangeal and metacar-pophalangeal joints.

Figure 6

Figure 6: Osteoarthritis. Anteroposterior footradiograph shows first metatarsophalangeal jointspace narrowing, sclerosis, and osteophyte for-mation (arrows).



mation, and possible dense effusionfrom hemorrhage. In addition to os-teopenia, epiphyseal overgrowth isseen, due to chronic hyperemia in child-hood (11). In the knees, elongation orsquaring of the patella and widening ofthe intercondylar notch may be seen(Fig 14). Repeated hemorrhage mayproduce a large expansile and destruc-tive abnormality known as hemophiliacpseudotumor, most commonly involving

Figure 7

Figure 7: Osteoarthritis. Anteroposterior kneeradiograph shows joint space narrowing, sclero-sis, and osteophyte formation (arrow) predomi-nately involving the medial compartment.

Figure 8

Figure 8: Osteoarthritis. (a) Anteroposterior and (b) frog-leg hip radiographs show superolateral joint spacenarrowing, sclerosis, subchondral cyst, and osteophyte formation (arrow) with buttressing of the femoral neck.

Figure 9

Figure 9: Atypical osteoarthritis due to trauma.Mortise ankle radiograph shows joint space nar-rowing, sclerosis, subchondral cyst, and osteo-phyte formation (arrow).

Figure 10

Figure 10: CPPD crystal deposition disease inthe hand. Posteroanterior radiograph shows sec-ond and third metacarpophalangeal joint spacenarrowing, sclerosis, subchondral cyst, and os-teophyte formation (arrowheads). Note chondro-calcinosis of the triangular fibrocartilage (arrow),and severe osteoarthritis of the first carpometacar-pal joint.

Figure 11

Figure 11: CPPD crystal deposition disease inthe knee. (a) Anteroposterior and (b) lateral radio-graphs shows chondrocalcinosis involving themenisci (arrowhead) and hyaline cartilage, pre-dominant patellofemoral joint osteoarthritis(straight arrow), and calcification of the gastrocne-mius tendon origin (curved arrow).



the femur and osseous pelvis. There isoften overlap between the radiographicfeatures of hemophilia and those of ju-venile chronic arthritis; however, knee,ankle, and elbow involvement are morecommon in hemophilia. Correlationwith patient history is also important inthe diagnosis of hemophilia.

Other less common causes for anatypical osteoarthritis appearance in-clude epiphyseal dysplasia, ochronosis,

Figure 12

Figure 12: Hemochromatosis.Posteroanterior hand radiographshows osteoarthritis of metacar-pophalangeal joints, with hooklikeosteophytes (arrowheads).

Figure 13

Figure 13: Neuropathic joint.(a) Anteroposterior and (b) lateralfoot radiographs show joint spacenarrowing, sclerosis, subchondralcyst, and osteophyte formation(arrows). Note plantar navicular tiltand pes planus.

Figure 14

Figure 14: Hemophilia. Anteroposterior kneeradiograph in 20-year-old man shows joint spacenarrowing that is somewhat symmetric, sclerosis,subchondral cyst, and osteophyte formation (ar-rowheads), with widening of intercondylar notch(arrows). Note flattening of distal femoral condylesurfaces.

Figure 15

Figure 15: Hemophilia. Lateral foot radiographshows joint space narrowing, sclerosis, and os-teophyte formation (arrows).



and acromegaly. With epiphyseal dys-plasia, multiple joints will be involved,with irregular articular surfaces and ab-normal shape of the epiphyses. Ochro-

nosis, a term that describes abnormalpigmentation in the disorder alkap-tonuria, is associated with characteris-tic multiple disk calcifications. With ac-

romegaly, other radiographic findingsinclude spade-shaped distal phalanges,initial widening of joint spaces, in-creased heel pad thickness, posteriorvertebral scalloping, and mandibularand sinus enlargement.

Figure 16

Figure 16: Juvenile chronic arthritis: Still disease. (a) Posteroanterior hand radiograph shows joint space narrowing and inflammatory changes at several joints, withepiphyseal overgrowth and other growth disturbances due to early epiphyseal fusion. (b) Bilateral anteroposterior knee radiographs show uniform joint space narrowing(arrows), osteopenia, and epiphyseal overgrowth with widening of the intercondylar notch (arrowheads). Note secondary osteoarthritis.

Figure 17

Figure 17: Early osteoarthritis.Posteroanterior radiograph of thefingers shows proximal and distalinterphalangeal joint space nar-rowing with minimal subchondralsclerosis and relatively few osteo-phytes.

Figure 18

Figure 18: Rheumatoid arthritis. Anteroposte-rior knee radiograph shows diffuse uniform jointspace narrowing.



Variations to Algorithm

In the presented algorithm as an ap-proach to the diagnosis of arthritis onradiographs, joint space narrowingwas used as an arbitrary startingpoint, primarily to emphasize the im-portant distinction between inflamma-tory and degenerative arthritis when

joint space narrowing is seen. How-ever, there are several conditions thatdo not precisely fit into the algorithm;these include juvenile chronic arthri-tis, inflammatory arthritis with sec-ondary osteoarthritis, erosive or in-flammatory osteoarthritis, gout, andsystemic lupus erythematosus. Al-though not discussed here, pigmented

villonodular synovitis and synovial os-teochondromatosis may cause second-ary osteoarthritis with pressure ero-sions, especially if the condition is

Figure 19

Figure 19: Rheumatoid arthritis with secondary early osteoarthritis. Posteroanterior hand radiographshows uniform joint space loss of each metacarpophalangeal joint. Note small erosions (arrowheads) andsmall osteophytes (arrows).

Figure 20

Figure 20: Rheumatoid arthritis with secondary osteoarthritis. Anteroposterior pelvis radiograph showsjoint space narrowing of each hip joint. Note small erosions (arrowheads) and osteophytes (arrows). Sacroil-iac joint involvement is also present with narrowing, irregularity, and sclerosis.

Figure 21

Figure 21: Inflammatory or erosive osteoar-thritis. Posteroanterior finger radiograph showsjoint space narrowing, sclerosis, and osteophyteformation of distal interphalangeal joint withprominent central erosion (arrow).

Figure 22

Figure 22: Gout. Posteroanterior hand radio-graph shows sclerotic erosion (arrow), with soft-tissue swelling and wide joint space.



longstanding and involves a joint ofsmall capacity.

Juvenile Chronic ArthritisThe category of juvenile chronic arthri-tis (or juvenile rheumatoid arthritis)consists of Still disease (or seronegativechronic arthritis), juvenile-onset adult-type rheumatoid arthritis, juvenile-on-set ankylosing spondylitis, psoriatic ar-thritis, arthritis of inflammatory boweldisease, other seronegative spondyloar-thropathies, and miscellaneous arthritis(12). This discussion will primarily fo-cus on Still disease because it is themost common type, accounting for 70%of cases of juvenile chronic arthritis.

Still disease has three subtypes:pauciarticular, polyarticular, and sys-temic. The most common is pauciarticu-lar disease (60% of cases), which in-volves the larger peripheral joints suchas the knees, ankles, elbow, and wristsand affecting one to four joints (13).Another subtype includes polyarticulardisease (20% of cases), commonly af-fecting bilaterally the hands, wrists,knees, ankles, and feet (Fig 16). A thirdsubtype, systemic disease (20% ofcases) may or may not be associatedwith arthritis but is characterized by fe-ver, rash, lymphadenopathy, hepato-splenomegaly, pericarditis, myocardi-tis, and anemia.

Common radiographic features ofarthritis in Still disease include soft-tis-sue swelling and osteopenia; however,there are several distinct differenceswhen compared with adult rheumatoidarthritis. These differences include de-layed joint space narrowing and erosivechanges, possible periostitis, growthdisturbances, and, later, joint fusion(Fig 16). The presence of periostitis isdue to the relatively loosely adherentperiosteum in children compared withthat in adults. Growth disturbances in-clude osseous overgrowth of the epiph-yses due to chronic hyperemia and boneundergrowth due to premature growthplate fusion.

Joint Space Narrowing without Erosionsor OsteophytesIn the presented algorithm, the firststep is to determine if erosions or osteo-

phytes are present in the setting of jointspace narrowing. In the absence of ei-ther erosions or osteophytes, one mustrely on the distribution of joint involve-ment, the characteristics of joint space

narrowing, and secondary signs of in-flammation to arrive at the correct diag-nosis. For example, if joint space nar-rowing involves the distal interphalan-geal joints in a 60-year-old patient

Figure 23

Figure 23: Gout. Anteroposte-rior foot radiograph shows multi-ple punched-out sclerotic ero-sions (arrows), with soft-tissueswelling.

Figure 24

Figure 24: Gout. Posteroanterior finger radio-graph shows substantial destruction centered atdistal interphalangeal joint (arrow).

Figure 25

Figure 25: Gout. Anteroposterior knee radio-graph shows punched-out sclerotic erosion (ar-row) and soft-tissue swelling (arrowheads).



without periarticular osteopenia or soft-tissue swelling, then early osteoarthritis islikely (Fig 17). If joint space narrowinginvolves the knee but symmetrically in-volves the joint with periarticular os-teopenia, then an inflammatory arthritissuch as rheumatoid arthritis is suggested(Fig 18). If joint space narrowing involvesa single joint with soft-tissue swelling andperiarticular osteopenia, then early septicjoint must be considered.

Inflammatory Arthritis with SecondaryOsteoarthritisA patient with chronic and possiblytreated inflammatory arthritis may de-velop secondary changes of osteoarthri-tis. Assessment using the presented algo-rithm becomes difficult in this situation,because a combination of erosions andosteophytes may be present involving thesame joint. There are several radio-graphic features that indicate inflamma-tory arthritis with secondary osteoarthri-tis. Many times, the most obvious feature

is involvement of a joint not typically af-fected by osteoarthritis, such as the meta-carpophalangeal joints. When osteo-phytes are identified in this situation, onemay initially consider causes for atypicalosteoarthritis. However, other findings ofunderlying inflammatory arthritis are of-ten present, such as symmetric jointspace loss and evidence for erosions (Fig19). Healed erosions may demonstrate asmooth or sclerotic margin. The charac-teristic distribution of joint abnormalitieswith inflammatory arthritis may also beseen, such as bilateral, symmetric, prox-imal involvement of the extremities or bi-lateral fifth metatarsophalangeal joint in-volvement, as seen in rheumatoid arthri-tis. The finding of symmetric joint spaceloss with osteophytes also suggests in-flammatory arthritis with secondary os-teoarthritis (Fig 20).

Inflammatory or Erosive OsteoarthritisInflammatory or erosive osteoarthritiscan be viewed as a variation of osteoar-

thritis in that it commonly involves theinterphalangeal joints of the hand, andosteophytes are quite obvious. The addi-tional characteristic feature is a centralerosion that produces two convexities ofthe joint surface, likened to the wings of aseagull (Fig 21). This central erosionshould not be confused with the marginalerosions of rheumatoid arthritis. Prolifer-ative synovitis is present, and consequentinflammation of the involved joint can re-sult in ankylosis (14).

GoutGouty arthritis is caused by monosodiumurate crystals, which display strong nega-tive birefringence at polarized light exam-ination. The radiographic features of goutdo not fit into the presented algorithm, inthat joint space narrowing occurs late(Fig 22). In addition, the erosions arecharacteristic in that they are frequentlynear a joint but not specifically marginaland they have sclerotic margins that pro-duce a punched-out appearance (Fig 23)(15). Periarticular osteopenia is also ab-sent. Another clue to the diagnosis of goutis the presence of marked soft-tissueswelling from gouty tophus deposition.Calcification of such tophi is uncommonin the absence of coexisting renal disease.Marked bone destruction occurs in se-vere cases, with substantial soft-tissueswelling (Fig 24). The most common sitefor gout involvement is the first metatar-sophalangeal joint of the foot. Otherjoints, such as the interphalangeal jointsof the hands and feet are not uncommon,although gout can occur in other joints aswell (Fig 25). Another characteristic sitefor gouty erosions are the tarsal bones.Rounded lucencies about a joint may rep-resent erosions or intraosseous tophi.Gout may also produce soft-tissue swell-ing from bursitis, such as olecranon bur-sitis. Because the radiographic findingsmay at times be confusing and appearquite unusual, it may be helpful to re-member, “When in doubt, think gout.”

Systemic Lupus ErythematosusThe radiographic features of systemiclupus erythematosus (SLE) may not beobvious, in that joint space narrowingand erosions are not frequent. The mostcommon finding with SLE is the pres-

Figure 26

Figure 26: Systemic lupus erythematosus. (a) Posteroanterior and (b) oblique hand radiographs showreducible subluxation and swan-neck deformities at several joints (arrowheads).



ence of reducible metacarpophalangealjoint subluxation without erosions; suchfindings are often identified only onoblique radiographs and are absent onposteroanterior views (Fig 26). Periartic-ular osteopenia and soft-tissue swellingmay be seen.

Conclusion

Once joint space narrowing is recog-nized, the presence of erosions suggestsan inflammatory arthritis, while thepresence of osteophytes indicates a de-generative arthritis. When osteoarthri-tis is suggested, it is important to takeinto account the distribution of joint in-volvement, the severity of disease, andage of the patient to consider less com-mon causes of cartilage damage. Onemust also be familiar with the arthriti-des that do not cleanly fit into the algo-rithm, such as gouty arthritis.

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Radiographic Evaluation of Arthritis ... · eral shoulder joints). Repetitive intraarticular hemorrhage, asseen with hemophilia, may cause car-tilage destruction and radiographic