Calcium pyrophosphate dihydrate crystal deposition disease: Imaging perspectives

Current Problems

Radiolo-

Dimostic Volume

29

in

Number

6 November/December

2000

Calcium Pyrophosphate Dihydrate Crystal Deposition Disease: Imaging Perspectives

Lynne S. Steinbach, MD Professor of Radiology University of California-San Francisco

Donald Resnick, MD Professor of Radiology Department of Veterans Affairs Medical Center University of California-San Diego

TT Calcium Pyrophosphate Dihydrate Crystal Deposition Disease: Imaging Perspectives Foreword

208

Abstract

210

introduction

210

Nomenclature

210

Epidemiology

211

and Classification

Pathophysiology

211

Clinical Manifestations

212

Treatment

212

Imaging Techniques for Detection of CPPD Crystal Deposition Conventional Radiography Computed Tomography and Magnetic Resonance Imaging

Disease

213 213 213

Imaging Characteristics Cartilage Synovium and Capsule Tendons, Ligaments, and Bursae Other Extra-articular Soft Tissues Common Sites of Involvement

215 216 216 217 217 218

Differential

227

Diagnosis

Conclusion

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References

227

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TT Calcium pyrophosphatedihydratecrystal depositiondiseaseis a relativenewcomer in the realm of arthritic diseases.It is a somewhatelusiveentity in that it may be seenas an incidental finding in somepatientsand in othersas a destrnctive, painful process.What is it, why doesit happen,and is it important?These issuesare nicely dealt with in this informative monographby Drs Steinbachand Resnick. Theodore

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E. Keats, MD Editor-in-Chief

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Lynne S. Steinbach, MD, graduated from Stanford University and attended the Medical / !@ College of Pennsylvania in Philadelphia. She did her radiology residency at New York Hospital-Cornell University and a musculoskeletal imaging fellowship at the Hospital for Special Surgery in New York City. Dr Steinbach has spent her professional career at the University of California San Francisco, where she is currently Professor of Radiology and Acting Chief of the Musculoskeletal Imaging section. She has written peer-reviewed articles and edited books on arthritis, musculoskeletal MRI, and imaging of AIDS in the musculoskeletal system.

+dw

!

Donald Resnick, MD, graduated from Hamilton College and attended the Cornell University ‘\B Medical College in New York, where he also completed his radiology residency. Dr Resnick served 2 years in the US Air Force and then spent his professional career at the University of California, San Diego, and Veterans Affairs Medical Center, San Diego, where he is currently a professor of radiology and Chief of Musculoskeletal Imaging. He has written over 790 peer-reviewed articles and 64 book chapters and has written or edited 12 textbooks on musculoskeletal imaging. He has also presented material at many medical meetings and has served as a visiting professor on numerous occasions.

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Calcium Pyrophosphate Dihydrate Crystal Deposition Disease: Imaging Perspectives Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease is widespread in elderly persons and has various clinical presentations that can be confounding to clinicians. It is characterized by acute, subacute, or chronic joint inflammation and deposition of CPPD crystals in hyaline cartilage, Iibrocartilage, and other soft tissue structures. We have learned a great deal about imaging findings of CPPD crystal deposition disease.New facts about the disorder and clues to radiologic diagnosis continue to be revealed. This article will provide a review of imaging characteristics of this disease with emphasis on some recent findings. The nomenclature, epidemiology, classification, and pathophysiology will be explained. A discussion of the clinical manifestations and treatment will be followed by a review of the characteristic imaging features.

Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease is induced by CPPD crystals. It is the most common crystalline arthropathy and is characterized by acute, subacute, or chronic joint inflammation and deposition of CPPD crystals in hyaline cartilage, fibrocartilage, and other soft tissue structures. This disease was first described in 1958 by Zitnan and Sitaj,1,2 who had seen radiographs of 27 patients with articular chondrocalcinosis, 21 of whom were members of five different Hungarian families. They termed the disorder “chondrocalcinosis polyarticularis.” Three years later Revault et al3 discussed 41 cases of this disorder, and the following year, McCarty emphasized the significance of CPPD crystals in synovial fluid and stressed the importance of chondrocalcinosis in this disorder. By that time, McCarty and Hollander had introduced compensated polarized microscopy as a method to identify negatively birefringent m-ate crystals in gout. Within a year, McCarty and coworkers used x-ray diffraction to identify weakly positive birefringent calcium pyrophosphate dihydrate crystals in knee effusions from patients with acute synovitis and chondrocalcinosis. Martel et al4 subsequently described the characteristic radiographic features in a prospective study in 1970. We have learned a great deal about imaging findings in CPPD crystal deposition disease.5 New facts about the disorder and clues to radiologic diagnodoi:10.1067/mdr.2000.107579

210

sis continue to be revealed. This article will provide a review of imaging characteristics of this disease with emphasis on some recent findings. Nomenclature One of the more confusing aspects of CPPD arthropathy is the associated nomenclature. A variety of terms have been used. We use the following guidelines, realizing that not everyone agrees with them. Chondrocalcinosis is a more general term that is reserved for pathologically or radiologically evident cartilage calcification. It can include CPPD, dicalcium phosphate dihydrate, calcium hydroxyapatite crystals, or combinations of the three. CPPD crystal deposition disease is a specific term for a disorder characterized by the exclusive presence of CPPD crystals in or around joints. The termpseudogout is not a radiologic diagnosis; rather, it is reserved for a gout-like clinical syndrome produced by CPPD crystal deposition disease that is characterized by intermittent acute attacks of arthritis. Pyrophosphate arthropathy is a term that describes a particular pattern of structural joint damage that occurs in CPPD crystal deposition disease. This arthropathy is similar to osteoarthritis but has some separate distinct features. Cartilage calcification may be absent on radiographs in patients with pyrophosphate arthropathy.6 Articular and periarticular calcijkation may occur with CPPD crystal deposition disease; however, calcium deposits other than CPPD crystal accumulation also can produce this type of calcification.

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Epidemiology

and

Classification

CPPD crystal deposition disease occurs with a frequency of 1 in 1000 persons, approaching 50% in patients 80 years of age or older.7*8 CPPD crystal deposition disease is more common in women and is rare in persons under the age of 50 years.7,8 It is practical to accept the diagnosis of CPPD crystal deposition disease when CPPD crystals are demonstrated in microscopic examination of synovial fluid or pathologic examination of articular tissues, tendons, or bursae. The diagnosis is considered probable when punctate and linear cartilage calcifications are found in two or more joints.9 CPPD crystal deposition disease can be classified as sporadic, hereditary, or secondary.rO The sporadic, or idiopathic, form tends to occur in middle-aged and elderly patients without a sexual predominance. 1l-t3 Different hereditary types have been described in families all over the world, although autosomal dominance is usual. The hereditary forms usually have a female predominance, appear at a relatively early age, and are accompanied by more severe arthropathy. CPPD crystal deposition may be seen in association with other diseases (ie, the secondary form of the disease). Because chondrocalcinosis is common in individuals over the age of 60 years, a cause-and-effect relationship with coexistent metabolic disorders is often difficult to prove. l4 Association with the four .H’s-primary hyperparathyroidism, hemochromatosis, hypomagnesemia, and hypophosphatasia-is well documented,15 but there are some doubters. In three series of consecutively studied patients with chondrocalcinosis, hyperparathyroidism was seen in 3% to 6% and hemochromatosis in 0% to 2%.16-18 Hypomagnesemia was found in only 1 of 115 patients studied. A proposed mechanism of secondary CPPD deposition in hyperparathyroidism is the associated hypercalcemia. Inhibition of inorganic pyrophosphatase by ferous iron is seen in hemochromatosis. Hemochromatosis may present radiographic changes similar to sporadic pyrophosphate arthropathy and should always be considered when CPPD crystal deposition disease is found, because iron removal can prevent hepatic cirrhosis. Differentiating features include more widespread metacarpophalangeal involvement, absence of scapholunate dissociation, multiple “ring cysts” in large joints, and subchondral bone fragmentation at the hip. l9 Loss of cofactor for pyrophosphatase may contribute to CPPD crystal deposition in hypomagnesemia. Hypophosphatasia is detected by finding a very low

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serum alkaline phosphatase level and elevated urinary ethanolamine level in a patient having metabolic bone disease. In hypophosphatasia, pyrophosphatase deficiency allows the accumulation of its substrate, inorganic pyrophosphate (PPi).20 Occasionally these patients present as young adults with chondrocalcinosis and fractures. A search for metabolic disease is warranted in the following situations: (1) early-onset arthritis; (2) florid polyarticular arthropathy (rather than pauciarticular); (3) recurrent acute attacks that occur more often than with chronic arthropathy; and (4) the presence of additional clinical or radiographic clues that suggest an associated metabolic disease (ie, bronze diabetes of hemochromatosis). Pathophysiology The pathogenesis of primary CPPD crystal deposition in cartilage is not known. Two mechanisms have been proposed for CPPD deposition in idiopathic disease: (1) overproduction or decreased removal of CPPD crystals from cartilage; (2) abnormality of underlying cartilage collagen. 21 Several factors may influence this deposition; however, the importance of age changes in normal cartilage or local tissue damage related to preexisting joint disease as a cause of crystal deposition has been reported in recent years and is part of the “amplification loop hypothesis.“22 It has been proposed that cartilage damage that occurs with increasing age predisposes to crystal deposition by changing the concentration of proteoglycan and inhibitory factors and increasing inorganic phosphate turnover.23,24 Secondary chondrocalcinosis of the knee meniscus also results from surgical intervention.25 This is attributed to liberation of intracellular pyrophosphates from chondrocytes into the extracellular space during surgery. Histologic, biochemical, and electron microscopic studies of a familial form of CPPD crystal deposition disease suggest that affected patients have a primary abnormality of the cartilaginous matrix with secondary crystal deposition.26 Other mechanisms for CPPD crystal deposition in cartilage have been postulated. A defect in the metabolism or production of PPi may be present because synovial fluid PPi concentration is elevated, especially after a pseudogout attack. 27 An elevated level of PPi in the joint is not specific for this arthropathy, having been demonstrated also in osteoarthritis. Elevated levels of extra-articular calcium-and pyrophosphatase inhibition

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by divalentions suchas iron, calcium, andcopper-have also been implicated. It is postulatedthat divalent ions may acceleratecartilage damage,producing structural joint changesin associationwith CPPD crystal deposition.28The earliest depositsappearin the midzone of hyaline cartilage,where thereis early loss of proteoglycan, andchondrocytecloning is occurring.21>29 Synovitis results when the CPPD crystals undergo phagocytosis by polymorphonuclear leukocytes, releasing chemotactic factors30 The acute exacerbations of the diseaseassociatedwith synovitis may be relatedto sheddingof the crystalswithin thejoint. Such sheddingis seenwith joint lavagewith crystal solubilizers, in patients with decreasedblood calcium concentration, and when there is significant cartilage destruction (as in neuropathic osteoarthropathyand infection). This is further substantiatedby the observation that radiologically evident chondrocalcinosis sometimesdisappearsduring pseudogoutattacks. CPPD crystalsoccasionallycoexistin the samearticular or periarticularsite with other crystalline deposits, including calcium hydroxyapatite and monosodium m-ate.Multiple typesof crystalsarefrequentlypresentin asymptomaticjoints. Urate, hydroxyapatite,and CPPD crystals can producecalcifications in gouty tophi. The significanceof the coexistenceof multiple crystal types in onelocation needsfurther investigation. Clinical

Manifestations

The clinical presentationsof CPPD crystal deposition diseasearehighly variable,ranging from asymptomatic diseaseto severe pain associatedwith a destructive arthropathy.Indeed,this diseasehasbeencalled a “great mimicker” of other arthritides.4Ryan and McCarty31 describedsix patternsof joint involvement.Furthermore, occasionallyseveralof theseclinical patternspresentat different times during the courseof the arthritis. The asymptomatic form of this arthropathyis probably the most common; however,it is difficult to document this because many asymptomatic patients are never seen by a physician. Absence of symptoms occurs in at least 10% to 20% of documentedcasesof CPPD crystal deposition disease. A large percentageof patients with CPPD crystal deposition diseasepresentwith an arthritis that simulates osteoarthritis.An occasional acute inflammatory component is seen in 35% to 60% of such patients. This osteoarthritic form is a chronic and progressive arthritis that is frequently bilateral and symmetric, presenting in the knee, hip, metacarpophalangeal,elbow, 212

ankle, wrist, and glenohumeraljoints. Flexion contracturesare common, especially in the knee and elbow. Patients with CPPD crystal deposition diseasealso may have inflammatory symptoms and signs. For example, attacks of pseudogoutoccur in 10% to 20% of symptomatic patients.The pseudogoutsyndromeis causedby the sheddingof pyrophosphatecrystals into the joint fluid. Although most cases of pseudogout develop spontaneously,situations that trigger acute pseudogoutinclude direct joint trauma, concomitent medical illness such as stroke and myocardial infarction, surgery (especially parathyroidectomy), blood transfusion,parenteralfluid administration, institution of thyroxine replacement therapy, and joint lavage. Hypocalcemia is present in many of these situations and is believed to provoke some attacks of pseudogout.32This producespain, erythema, and tenderness that can be mistaken for other disorderssuch as a gout or a septic joint. The attacks are self-limited and can last from 1 day to severalweeks. They generally are less painful than those of gout and are most common in the knee, but other sites including the hip, glenohumeral, elbow, ankle, wrist, acromioclavicular, talocalcaneal, and metatarsophalangealjoints also are affected. Fever and elevation of the erythrocyte sedimentation rate may accompanypseudogoutattacks. Two percent to 6% of patients with CPPD crystal deposition diseasepresentwith an arthritis that simulates rheumatoid arthritis. These attacksare characterized by morning stiffness,fatigue, synovial thickening, restrictedjoint motion, andan elevatederythrocytesedimentation rate, and they persist from 4 weeks to several months. CPPD crystal deposition diseasealso can have a pseudoneurotrophicpresentationin as many as 2% of patients.33-37Indeed, CPPD crystalline arthropathy should be consideredin the differential diagnosis of rapidly progressivedestructionof largejoints. Other miscellaneousanduncommonclinical presentations of CPPD crystal deposition disease include symptoms suggestiveof rheumatic fever,psychogenic disease,trauma, and ankylosing spondylitis.38-41 Treatment

Therapy for CPPD crystal depositiondiseaseis directed at the relief of symptoms.No methodsto alter crystal deposition or hastencrystal removal have yet been found. Treatmentincludes aspirationof large effusions, non-steroidal anti-inflammatory medication, intraarticular injection or oral dosesof corticosteroids,and Curr Probl

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low doses of colchicine, all of which are helpful if the patient has recurrent episodes of pseudogout. There is no medical treatment for the calcific deposits and polyarticular and progressive degenerative changes that occur in elderly patients with CPPD crystal deposition disease. Successful treatment of associated conditions such as hyperparathroidism and hemochromatosis does not reverse chondrocalcinosis or pyrophosphate arthropathy. Total joint replacement is often performed on knees, hips, and shoulders with degenerative joint disease caused by CPPD crystal deposition. Laminectomies are performed for cervical myelopathy and lumbar stenosis related to CPPD crystal deposition. FIG

Imaging Crystal

Techniques Deposition

Conventional

for Detection Disease

of CPPD

Radiography

Radiographically, chondrocalcinosis usually is apparent in CPPD crystal deposition disease, but the arthropathy can also precede radiographically detectable cartilage calcification, the calcification may not always be dense enough to be visualized on conventional radiographs, or it may be difficult to identify such calcification if the joint is severely deranged.42,43 In one study of 3228 patients undergoing knee arthroscopy, a radiographic diagnosis of chondrocalcinosis was made in only 39.2% of patients with pathologically proved CPPD crystal deposition.25 Computed Resonance

Tomography imaging

and Magnetic

Computed tomography (CT) can accurately demonstrate chondrocalcinosis because of the high soft tissue contrast and tomographic nature of this imaging method (Fig 1). However, CT is rarely used to evaluate the painful joint. Magnetic resonance imaging (MRI) is often the crosssectional imaging procedure performed for painful joints. It is therefore common to encounter CPPD crystal deposition disease in older patients who are being studied with routine MRI. CPPD crystal deposition disease in hyaline cartilage usually is detected with standard MRI techniques@ (Figs 2 and 3). Prominent linear or punctate hypointense areas frequently are demonstrated. A small halo of hyperintense signal intensity surrounding the hypointense areas is occasionally seen, probably related to magnetic susceptibility artifact. Although the low signal intensity calcification can be detected in routine spin echo, fast spin echo, and short tau inversion recovery (STIR) images, the hyaline

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1. Calcification

ligaments

along

is easily the proximal

recognized aspects

in the hyoline of the scaphoid,

cartilage lunate

and and

tri-

quetrum [arrows) on this coronal CT of the wrist in an older patient with avascular necrosis of the proximal scaphoid after a fracture. (From Steinbach LS, Resnick D. Imaging of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. In: Smyth editors, Gout, hyperuricemia and other crystal-associated New

York:

Marcel

Dekker;

1999.

CJ, Holers VM, arthropathies.

By permission.)

cartilage calcification is better seen in gradient echo images in which the difference between the magnetic susceptibility of hyaline cartilage and CPPD crystals is enough to create local .magnetic field inhomogeneity resulting in signal distortion (Figs 2 and 3). In these types of images, the foci of cartilage calcification become larger-the so-called “blooming” effect. Low signal intensity in the hyaline cartilage may be overlooked on MRI if the reader does not include it in a search pattern for chondrocalcinosis. There is also a differential diagnosis for this pattern that includes hemosiderin from trauma, pigmented villonodular synovitis, and hemophilia; gas related to vacuum phenomenon; and magnetic susceptibility artifact around postsurgical intra-articular material such as micrometallic debris. At times, chondrocalcinosis demonstrated at arthroscopy or after total joint replacement has been seen with MRI but not with conventional radiography.44 This can be related to the high soft tissue contrast, magnetic susceptibility, and tomographic nature of MRI. The capability of MRI for early detection of chondrocalcinosis poses the intriguing question about the future use of this method to detect chondrocalcinosis in patients in whom it is not radiographically evident. It remains to be seen whether this is a clinically important role for MRI, but the detection of CPPD crystals may explain patients’ symptoms if radiographs and MRX are otherwise unremarkable.

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FIG 2. A, Hyaline cartilage calcification is demonstrated that parallels the posterior femoral condyles (arrows) on an off-lateral radiograph of the knee. B, Corresponding gradient echo T2* sagittal MRI through the medial compartment of the knee shows the calcification as o region of low signal intensity within the hyaline cartilage (arrow). (From Steinbach LS, Resnick D. Imaging of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. In: Smyth CJ, Holers VM, editors. Gout, hyperuricemia and other crystalussociated arthropathies. New York: Marcel Dekker; 1999. By permission.)

FIG 3. Hyaline cartilage calcification presents OS linear low signal intensity material along the edge of the hyaline cartilage of the posterior patella (arrows) on an axial gradient echo image of the knee. There is also a large intra-articular effusion.

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There are also documented cases of CPPD crystal deposition in which the calcification in the hyaline cartilage or menisci was not seen on MRI.44 This is more common in cases of meniscal calcification in which the short T2 relaxation times of the meniscus and calcification are similar. Occasionally with MRI CPPD crystal deposition disease in a meniscus can mimic a meniscal tear.45 This has important implications and can lead to inappropriate treatment including unnecessary surgery. Gale et a146 reported areas of high signal intensity in regions of meniscal chondrocalcinosis with T2-weighted spin echo MR sequences. This finding may be attributed to the hyperintense halo artifact seen adjacent to calcification of low signal intensity. No reports have described high signal intensity in areas of chondrocalcinosis in Tl-weighted images. Such a finding that would potentially simulate a meniscal tear is theoretically possible given that increased signal inten-

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FIG 4. Anteroposterior (A) and lateral (6) radiographs of the knee show synovial osteochondrosis associated with CPPD arthropathy. A large loose body lies in the suprapatellar bursa (arrow). There is a smaller one in a popliteal cyst (arrowhead). There are degenerative changes in the patellofemoral joint. (From Steinbach LS, Resnick D. Calcium pyrophosphate dihydrate crystal deposition disease revisited. Radiology 1996;200:

l-9.

By permission.)

sity of calcium deposits has been described in the disks of the lumbar spine47 and the brain.48,49 Imaging

Characteristics

CPPD crystal deposition disease is characterized by calcification in and around joints and structural joint changes termed pyrophosphate arthropathy. This arthropathy resembles osteoarthritis; however, it occurs in articulations not usually affected by osteoarthritis, often affecting non-weight-bearing regions such as the radiocarpal, metacarpophalangeal, and glenohumeral joints, followed in frequency by the hip, glenohumeral joint, and elbow. It usually is bilateral and symmetric and is most common in the knee, wrist, and metacarpophalangeal joints. Furthermore, CPPD crystal deposition disease has an unusual intra-articular distribution in certain joints

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such as the knee and wrist, where patellofemoral and radiocarpal joint space narrowing may be seen. CPPD crystal deposition disease frequently presents on routine radiography with normal mineralization, narrowing of various articulations, and subchondral sclerosis. Osteophytes are common but occur with a frequency less than that of osteoarthritis. Subchondral cysts are among the hallmarks of this arthropathy. The cysts usually are larger, more numerous, and more widespread than those in osteoarthritis. Cysts may form before cartilage loss is evident. Osseous fragmentation and collapse may be related to fracture of these cystic lesions. Intra-articular osteochondral bodies commonly are associated with CPPD crystal deposition disease50 (Fig 4). These may be free in the joint cavity or embedded in cartilage or synovium. 215

FIG 7. Linear and adductor graph. FIG 5. Linear hyaline cartilage calcification (black arrowheads) and triangular fibrocartilage calcification (w/rife arrows) are present on this posteroanterior flexed standing view of the knee.

calcification is present tendons (arrowheads)

in the symphysis pubis on this anteroposterior

(arrows]

radio-

(Fig 5). CPPD crystals are also deposited on the surface of the hyaline cartilage, especially when there is superficial chondral erosion.5 1,52 Hyaline cartilage calcification is most common in the wrist, knee, elbow, and hip. CPPD crystal deposition in fibrocartilage is most commonly observed in the menisci of the knee (Fig 5), triangular fibrocartilage of the wrist (Fig 6), labra of the acetabulum, symphysis pubis (Fig 7), and annulus fibrosus (Fig 8) of the intervertebral disk.36 Other, less-common sites of CPPD crystal deposition in cartilage include the articular disks of the stemoclavicular and acromioclavicular joints (Fig 9) and glenoid labra.53354

Synovium and Capsule

FIG 6. Calcification is present in the triangular fibrocartilage (black arrow), hyaline cartilage (curved black arrowj, and lunotriquetral ligament (white arrowhead) on this posteroanterior radiograph of the wrist.

Cartilage Chondrocalcinosis is usually caused by CPPD crystal deposition. In 5% of cases, however, it can be related to other crystals such as dicalcium phosphate dihydrate and calcium hydroxyapatite. 6 Both hyaline cartilage and fibrocartilage can contain CPPD crystals. The CPPD crystal tends to be deposited in the middle layer of degenerated hyaline cartilage. These deposits are thin and linear and parallel the subjacent subchondral bone

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Synovial calcification is common in CPPD crystal deposition disease.50 Synovial calcification can be so widespread that it appears to fill the entire joint cavity, mimicking synovial osteochondromatosis.50 Synovial deposits are more common in the wrist, knee (Fig lo), metacarpophalangeal, and metatarsophalangeal joints. Calcium hydroxyapatite crystals also are deposited in the synovium, particularly if there are associated severe degenerative changes. The synovial membrane may demonstrate acute and chronic inflammatory changes in association with CPPD crystal deposition disease. It is not known whether the crystals migrate into the synovium from the adjacent cartilage or are deposited directly within the synovium. Capsular calcification may appear as a linear peripheral density and may be difficult to distinguish from early synovial calcification. It is most commonly observed in the elbow, glenohumeral, metatarsophalangeal, and metacarpophalangeal joints.

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FIG 9. Amorphous calcification joint (arrow) on this anteroposterior

FIG 8. Calcification within the annulus els of the lumbar spine (arrows) is noted graph of the lumbar spine.

h-dons,

ligaments,

and

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in the acromioclavicular radiograph.

fibrosus of the disk at all levon this anteroposterior radio-

Bursae

Tendon calcifications are observed with high frequency in patients with CPPD crystal deposition disease.43>55>56 An incidence of 13.5% was reported in such patients in one study.56 Those tendons more frequently involved include the supraspinatus (Fig ll), triceps, quadriceps (Fig 12), gastrocnemius (Figs 12 and 13), and Achilles (Fig 14) tendons. Hip adductor (Fig 7), rectus femoris (Fig 15), and hamstring tendon calcification may also be seen. Tendon calcifications commonly are linear or punctate and usually can be distinguished from the more homogeneous, discrete, and nodular calcifications of calcium hydroxyapatite crystal deposition36 (Fig 16). Calcification often extends far from the tendon attachment. There is a high correlation between the existence of these tendon calcifications and the extent and intensity of calcific deposits in other joints.55 Direct translocation of CPPD crystals from the articular or bursal surfaces may be responsible for some of the tendinous calcification.57

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FIG 10. Faint synovial calcification is present bursa (arrow) on this lateral knee radiograph.

in the suprapatellar

Ligaments can also calcify. Sometimes the calcification is not dense enough to be visualized on conventional radiographs; however, we have recently seen cruciate ligament involvement in a cadaveric case with CPPD crystal deposition disease (Fig 17). The ligamentum flavum (Fig 18) and dura mater can contain calcific deposits. Bursal calcification is most common in the olecranon and subacromial bursae. Other

Extra-articular

Soft Tissues

Soft tissue and vascular calcification may be seen in CPPD crystal deposition disease.43,58-61 In particular, tumor-like masses of CPPD crystals can be seen in the extra-articular soft tissues (Fig 19). This manifestation of

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FIG 1 1. There is linear calcification in the distal supraspinatus tendon (white arrow) and along the hyaline cartilage of the humerus (black arrow). (From Steinbach LS, Resnick D. Imaging of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. In: Smyth CJ, Holers VM, editors. Gout, hyperuricemia and other crystal-associated arthropathies. New York: Marcel Dekker; 1999. By permission.)

FIG 12. Linear

calcification is deposited in the quadriceps (white and the gastocnemius (b/ad arrow) tendons as well as the posterior capsule of the knee joint (arrowhead) on this lateral knee radiograph.

arrow)

FIG 13. Thick curvilinear calcification outlines the medial mius tendon (black arrow) on this lateral knee radiograph. also calcification of the posterior meniscus (white arrow).

gastrocneThere is

ical locations.62 The patients ranged in age from 3 1 to 86 years, and 6 of them were women. These crystalline masses have been seen near the elbow, finger, jaw, acromioclavicular joint, and hip.63 Lesions are solitary and usually occur in areas of chondroid metaplasia without predisposing metabolic abnormality. Although the mechanism for development of these masses is not known, it has been postulated that hypertrophic metaplastic chondrocytes accumulating proteoglycans intracellularly provide a seeding site for crystal formation. These calcified masses may initially be mistaken for benign or malignant chondroid or other soft-tissue tumors, tophaceous gout, and tumoral calcinosis.63364 Misdiagnosis sometimes leads to unnecessary surgery. The patterns of calcification usually can be differentiated from the lobular pattern of calcification in tumoral calcinosis by their granular and more delicate appearance.65,66 Calcified soft tissue masses related to CPPD crystal deposition are of intermediate to low signal intensity on MR imaging examinations. 67 They can present as the only manifestation of CPPD crystal deposition disease.62 Pressure erosion of adjacent osseous structures may be seen. It is important to identify the CPPD crystals, as these masses have also been mistaken for malignant cartilaginous tumors on histologic evaluation because of the presence of chondroid metaplasia.62>63

Common Sifes of Involvement CPPD crystal deposition disease, known as tophaceous pseudogout, is rare. In one study, 7 cases of massive focal CPPD crystal deposition disease were identified in atyp-

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The joints most frequently involved are the knee, wrist, symphysis pubis, elbow, and hip. Unlike osteoarthritis, the glenohumeral joint and elbow often are involved.

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FIG

15.

Hyaline

cartilaginous

and

fibrocartilage

acetabular

labrum

lar calcification superolateral also an extra-articular linear the site of the rectus cartilage calcification

calcification is associated

in the hip. The fibrowith

a typical

femoris tendon (open arrow). Curvilinear parallels the medial femoral head

heads). (From Steinbach drate crystal deposition

triangu-

to the femoral head (arrow). There calcification lateral to the acetabulum,

LS, Resnick D. Calcium pyrophosphate disease revisited. Radiology 1996;200:

is at

hyaline (arrowdihyl-9.

By permission.)

FIG 14. calcification

Tendon calcification of the Achilles

in CPPD arthropathy. tendon (arrow). There

lage calcification in the ankle joint Resnick D. Calcium pyrophosphate ease

revisited.

Radiology

Extensive was hyaline

(not shown). (From Steinbach dihydrate crystal deposition

1996;200:1-9.

linear cartiLS, dis-

By permission.)

An ideal screening series for detecting chondrocalcinosis includes anteroposterior radiographs of each knee, posteroanterior radiographs of each wrist, and an anteroposterior radiograph of the pelvis. Knee. The knee is the most commonly involved joint in CPPD crystal deposition disease. Pyrophosphate

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arthropathy most commonly involves the medial femorotibial compartment.36 Isolated patellofemoral narrowing is a finding that should suggest underlying CPPD crystal deposition disease in the older patient, even in the absence of joint calcification (Fig 20). Anterior femoral scalloping is occasionally seen proximal to the patella, related to abutment of the patella against the femur. Similar patellofemoral changes may appear in patients with osteoarthritis or in those with primary hyperparathyroidism or renal osteodystrophy without CPPD crystal deposition disease. Wedge-shaped meniscal calcification is more frequent than linear hyaline cartilage calcification,60 and the lateral meniscus is more commonly calcified than the medial meniscus. Chondrocalcinosis is thought to be a result of post-traumatic meniscal changes, degenerative meniscal changes, or both types of changes.25

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FIG neous,

16.

Hydroxyapatite discrete,

and

calcification globular

the triangular fibrocartilage rior wrist radiograph.

than region

(white

arrow)

the punctate (black

arrow)

is more

CPPD

homoge-

calcification

in

on this posteroante-

Posterior hyaline cartilage calcification is more common than anterior hyaline cartilage calcification.57 As previously discussed and illustrated, the synovium, capsule, ligaments, and tendons also may be calcified, and these findings are of aid in diagnosing CPPD crystal deposition disease in joints with advanced cartilage loss where visualization of chondrocalcinosis is difficult. Medial or lateral gastrocnemius tendon calcification was seen in 15 of 37 patients with CPPD crystal deposition disease in a recent study57 and was exclusive to this disorder. The quadriceps tendon can also calcify, although less commonly than the gastrocnemius (Figs 12 and 13). Intra-articular bodies occasionally are seen in association with degenerative changes of the cartilaginous and subchondral regions (Fig 4). Wrist and Hand. In the wrist, the lunotriquetral ligament has been shown in some reports to be a more common site of calcification than the triangular fibrocartilage (TFC)(Figs 1 and 21), although the TFC is frequently calcified6* (Fig 6). Degenerative tears of the TFC and degeneration of the articular cartilage of the lunate have been associated with CPPD crystal deposits. 6g Hyaline car tilage calcification is most frequent between the scaphoid and lunate (Fig 1).

220

FIG

17.

Anterior

and

posterior

cruciate

ligament

calcification

in

CPPD arthropathy. CPPD crystal deposition is demonstrated on a sectional lateral radiograph of a cadaver knee (A)(whife arrow). The linear CPPD crystalline deposits are confirmed on a photograph of the specimen (B)(b/ack arrow). Note of the joint. (Courtesy of Joachim Resnick D. Calcium pyrophosphote ease revisited. Radiology 1996;200:

the subchondrol Brossmann, MD.

cysts From

on both sides Steinbach LS,

dihydrate crystal deposition l-9. By permission.)

dis-

There often is associated radiocarpal joint space narrowing (Fig 22). A scapholunate advanced collapse (SLAC) pattern of arthritis, also seen after wrist trauma, is the most common form of structural joint damage in the wrist in patients with CPPD crystal deposition disease. 4,6g,70 Compromised scapholunate and volar radioscapholunate ligaments subsequently lead to rotary subluxation of the scaphoid and scapholunate dissociation in the SLAC wrist. The capitate then migrates proximally and dorsally into the abnormally large space that exists between the capitate and lunate with eventual degenerative change in the radiocarpal joint. The scaphoid moves proximally and may appear deformed or compressed by the adjacent radius (Fig 22). This results in the “stepladder” appearance. There is often narrowing

Curr Probl

Diagn

Radiol,

November/December

2000

19.

Multiple

wrist

teroanterior

FIG

wrist

study

phate distal

arthropathy: radius that

abnormalities demonstrates

several

(1) a large, well-circumscribed represents a subchondral cyst

(2) a similar radiocarpal

but smaller cyst joint narrowing,

(solid arrow);

urrow); (4) scapholunate

black (5)

in CPPD

This

pos-

of pyrophos-

lytic lesion in the (hollow black arrow);

is seen in the capitate (arrowhead); (3) particularly at the lunate articulation

narrowing dissociation

deposit of CPPD crystals in the soft the distal radioulnar joint, producing of the ulna (white arrows). pyrophosphate dihydrate Radiology 1996;200:1-9.

arthropathy. features

of

the triscaphe joint (diamond); and (6)

tissues around erosion along

(curved tumoral

the distal the radial

(From Steinbach LS, Resnick crystal deposition disease By permission.)

ulna at aspect

D. Calcium revisited.

of the radioscaphoid and capitolunate joint spaces. The radiolunate space generally is spared.71-73 A dorsal intercalated segment instability pattern commonly ensues. The triscaphe joint (located between the scaphoid, trapezium, and trapezoid) also is commonly affected in CPPD crystal deposition disease (Fig 21). Narrowing of the metacarpophalangeal joints (especially the second and third) also is frequent in CPPD crystal deposition disease (Fig 22), with sparing of or only mild changes in the interphalangeal joints. The metacarpophalangeal joint may also reveal sclerosis, cyst formation, and subchondral collapse, particularly of the metacarpal head. Another finding in this disease is that of the so-called “drooping osteophytes,” which are seen along the radial aspects of the metacarpal

FIG 18. The ligamentum flavum and on a sagittal CT reformation addition, there is some calcification of calcium tal-associated

Curr

Probl

pyrophosphate arthropathies.

Diagn

Radiol,

is calcified (black arrows) on this axial CT image (A) obtained in the upper lumbar region with bone windows of the lumbar spine (8) in the same patient. Notice that the annulus fibrosus is also calcified (arrowheads). In of the capsule surrounding a degenerated facet joint (white arrow). (From Steinbach IS, Resnick D. imaging

dihydrate (CPPD) crystal deposition New York: Marcel Dekker; 1999.

November/December

2000

disease. In: Smyth By permission.)

CJ, Holers

VM,

editors.

Gout,

hyperuricemia

and

other

crys-

221

FIG 20. Isolated patellofemoral joint narrowing (arrow) can be seen on this lateral knee radiograph. When this finding is seen in the presence of normal medial and lateral compartment joint width, it is suggestive of CPPD crystal deposition disease, the diagnosis in this patient.

FIG 21. The lunotriquetral ligament (open arrow) and hyaline carfilage (black arrow] along the proximal aspect of the triquetrum are caicified on this posteroanterior wrist radiograph. Also note the narrowing and sclerosis of the triscaphe joint (curved arrow), a finding in CPPD crystal deposition disease.

heads (Fig 22). This feature is more characteristic of hemochromatosis, however (Fig 23). Patients with hemochromatosis often have CPPD crystal deposition disease with specific involvement of the second and

222

FIG 22. SLAC wrist, metacarpophalangeal, and other carpal joint involvement associated with CPPD arthropathy. The radioscaphoid and capitolunate joints are narrowed with subchondral sclerosis typical of scapholunate advanced collapse (arrowheads). There is also involvement of the triscaphe joint (hollow arrow). The degenerative changes of the first carpometacarpal joints are frequent in osteoarthritis; however, the presence of large subchondral lucencies that probably repro sent cysts favors underlying pyrophophate arthropathy in this joint, as well (solid black arrow]. Such cysts are also seen adjacent to the second and third metacarpophalangeal joints, which are narrowed with drooping osteophytes, which is typical for this arthropathy (white arrows). There is a loose body in the radiocarpal joint, and the prestyloid recess is calcified [curved whife arrows). Cartilage and ligament calcification is present at the ulnocarpal articulation. (From Steinbach LS, Resnick D. Calcium pyrophosphate dihydrate crystal deposition disease revisited. Radiology 1996;200:1-9. By permission.)

third metacarpophalangeal joints. The fourth and fifth metacarpophalangeal joints are involved more frequently in patients with hemochromatosis than in those with idiopathic CPPD crystal deposition disease19 (Fig 23). It must be remembered that persons engaged in manual labor may develop similar changes in the metacarpophalangeal joints; this has been termed the Missouri metacarpal syndrome.74 Capsular calcification is occasionally identified in CPPD crystal deposition disease, especially about the metacarpophalangeal joints. Carpal tunnel syndrome is seen in association with synovitis related to CPPD crystal deposition disease. 69175A carpal tunnel view or

Curr Probl

Diagn

Radiol,

November/December

2000

FIG

23.

A patient

with

metacarpophalangeal hand radiograph. of the proximal

hemochromatosis joints

(white

has arrows]

narrowing on

The study was done because diaphysis of the fifth metacarpal

is a drooping osteophyte along the metacarpal head (open black arrow).

FIG 24. Calcification this carpal tunnel view

is present obtained

this

of all of the posteroanterior

of an acute fracture (black arrow]. There

radial

aspect

within the carpal in a patient with

of

the

third

tunnel (arrows) on CPPD crystal depo-

sition disease and acute symptoms of carpal tunnel syndrome. f, Pisiform. (From Steinbach LS, Resnick D. Imaging of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. In: Smyth CJ, Holers VM, editors. Gout, hyperuricemia and other crystal-associated arthropathies. New York: Marcel Dekker; 1999. By permission.)

cross-sectional imaging with CT scanning can demonstrate the calcifications in the carpal tunnel (Fig 24). Elbow. Hyaline cartilage (Fig 25), capsular, and synovial calcification is occasionally visualized in this joint. The extensor, flexor, biceps, and triceps tendons

Curr

Probl

Diagn

Radiol,

November/December

2000

FIG 25. This septic arthritis,

man had acute but it was found

radiographs were reveal calcification bursa surrounding tuberosity on analysis infection.

(arrows).

elbow pain to represent

clinically diagnosed a pseudogout attack

as a once

reviewed. Lateral (A) and oblique (B) radiographs of the hyaline cartilage (arrowheads) and of the the insertion of the biceps tendon at the radial Weakly

of the elbow

positive joint

effusion,

birefringent and

there

crystals was

were

found

no evidence

of

may calcify. CPPD crystal deposition disease is accompanied by joint space narrowing, resorption of the proximal portion of the ulna and radius, subchondral sclerosis and cyst formation, and bone fragmentation. Surrounding bursae including the olecranon and radio-

223

FIG 26. Calcification is present in the symphysis pubis (open arrow) and left hip hyaline cartilage (arrow) on this anteroposterior radiograph of the hips. (From Steinbach LS, Resnick D. Imaging of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. In: Smyth CJ, Holers VM, editors. Gout, hyperuricemia and other crytal-

bicipital bursa (Fig 25) can contain CPPD crystals. Elbow contractures also develop in association with CPPD crystal deposition disease. Symphysis Pubis. This fibrocartilaginous joint frequently demonstrates calcification (Figs 7 and 26) and occasional severe erosive changes.36 Considerable bone fragmentation is occasionally seen in this region in patients with CPPD crystal deposition disease. Hip. As in the knee, calcification is seen in both fibrocartilage and hyaline cartilage (Fig 15). The calcitied acetabular labrum presents as a small radiodense triangle along the peripheral aspect of the acetabulum superolaterally (Fig 15). Chondrocalcinosis is often apparent in the hyaline cartilage leading to a radiodense curvilinear line that parallels the femoral head (Fig 26). Surrounding tendons, including the rectus femoris (Fig 15), hamstrings, and adductor insertion (Fig 7), may also calcify. Narrowing of the hip joint is commonly superolateral, in a pattern similar to osteoarthritis. Alternatively, the hip joint may reveal concentric narrowing with axial migration, simulating the appearance of an inflammatory arthropathy. A rapidly destructive pattern of osteoarthritis in the hip has been described.76 The cause is not known, but some cases may be related to CPPD crystal deposition disease. Glenohumerd Joint. In the glenohumeral joint, CPPD crystal deposition disease resembles osteoarthritis with subchondral bone formation and cysts and osteophytes (Fig 27). Tendinous, capsular, and bursal deposits are occasionally seen. Rotator cuff tears are common in patients with CPPD crystal deposition disease (Fig 28). The “Milwaukee shoulder syndrome” is a rapidly progressive, destructive arthritis character-

224

FIG 27. The glenohumeral joint is narrowed, with small subchondrai lucencies compatable with cysts and sclerosis, and there is an inferomedial osteophyte (arrow) related to CPPD crystal deposition disease, which is a common cause of degenerative changes in the shoulder. There was no calcification in the shoulder joint; however, the knees of this patient showed chondrocalcinosis. (From Steinbach LS, Resnick D. Imaging of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. In: Smyth CJ, Holers VM, editors. Gout, hyperuricemia and other crystal-associated arthropathies. New York: Marcel Dekker; 1999. By permission.)

ized by recurrent large effusions, rotator cuff tear, and destruction of cartilage and subchondral bone.77-7g It is most common in older women who often relate a history of trauma to the affected shoulder. It probably represents a severe form of mixed CPPD and calcium hydroxyapatite crystal deposition disease,” although some believe that it is purely a manifestation of calcium hydroxyapatite crystal deposition disease. Acromioclavicular Joint. CPPD crystal deposition disease also occurs in the acromioclavicular (AC) joint.53,54so This is a relatively infrequent but clinically important site of involvement. A calcified or cystic mass can present in the region of the AC joint (Fig 9), often just above the articulation. Calcification is most common in the articular disk. In one series, 65% of the AC joints had soft tissue swelling and calcified deposits above the joint. 53 It may be difficult to identify the fibrocartilaginous calcification on conventional radiographs because of the obliquity of the joint. Careful evaluation of radiographs of this joint with a bright light is recommended, especially in elderly patients with acute shoulder pain and no history of trauma, to exclude CPPD crystal deposition disease.

Curr Probl

Diagn

Radiol,

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2000

FIG

29.

Capsular

calcification

is seen

medial

metatarsophalangeal joints (arrows). In addition, erative change of the first metatarsophalangeal hallux valgus, unrelated Steinbach LS, Resnick FIG 28. There is a full-thickness al retraction and muscle atrophy and fat-suppressed patient had CPPD that was humerus.

associated

fast spin echo crystal deposition with

the

supraspinatus tendon tear with on oblique-coronal Tl-weighted

medi-

T2-weighted (B) MR images. disease in the glenohumeral

This joint

chronic

tear

and

resultant

(A)

Diagn

Radiol,

November/December

2000

Marcel

Dekker;

(From dihy-

disease. In: Smyth CJ, Holers VM, ediother crystal-associated arthropathies.

1999.

By permission.)

high-riding

Cooper et a154 discussed the importance of recognizing the presence of underlying CPPD crystal deposition disease when a calcified mass is seen around the acromioclavicular joint, to avoid misdiagnosis and inappropriate surgery. Ankle and Foot. Calcification is not common in the ankle joint in patients with CPPD crystal deposition disease, and arthropathy in this site is unusual. The talonavicular joint may be selectively affected when CPPD crystal deposition disease involves the ankle and hindfoot. In this location, joint space narrowing, subchondral sclerosis, fragmentation, and dorsal soft tissue swelling are seen that resemble the appearance of a neuropathic joint. The adjacent Achilles tendon (Fig 14) and plantar fascia may be calcified.56 Capsular calcification may be seen in the forefoot, especially about the metatarsophalangeal joints (Fig 29). Soft tissue

Curr Probl

York:

second

there is mild degenjoint associated with

to the CPPD crystal deposition disease. D. Imaging of calcium pyrophosphate

drate (CPPD) crystal deposition tors. Gout, hyperuricemia and New

to the first and

swelling and periarticular calcification medial to the first metatarsophalangeal joint can simulate radiographic findings of gout. Spine. CPPD crystal deposition disease of the spine usually is asymptomatic. Many of the patients with CPPD crystal deposition disease are elderly and have unrelated degenerative disease of the spine. CPPD crystal deposition disease can produce severe degenerative disk disease often involving multiple levels, however. The spine may be the only site affected by CPPD crystal deposition disease. 81 Acute and chronic CPPD crystal deposition disease can produce destructive lesions of vertebral bodies and disk spaces that can be confused with infectious diskitis or neuropathic disease. Severe bone sclerosis, intervertebral disk space narrowing, and osteophyte formation in CPPD crystal deposition disease can simulate a neuropathic disorder. A destructive arthropathy that can lead to spondylolisthesis also may be noted in the facet joints. CPPD crys-

225

FIG

31.

(arrow)

FIG

30.

This

patient

was

having

CPPD crystal deposition disease. ligament is well seen on axial images [arrows). The spinal cord ligament

and

surrounding

upper

cord

symptoms

The calcification (A) and reformatted is being compressed

related

to

of the transverse (B) sagittal CT by the calcified

inflammation.

tals can deposit in either the annulus fibrosus (Fig 8) or nucleus pulposus of the disk or in both structures. Calcification usually begins in the outer fibers of the annulus fibrosus. Thin, vertical annular calcification can simulate the syndesmophytes of ankylosing spondylitis. The nucleus pulposus is less commonly calcified in CPPD crystal deposition disease,58 but cal-

226

There on this

is linear

calcification

anteroposterior

in the lower

view

right

sacroiliac

joint

of the sacrum.

cification of this structure may be seen in patients with a genetic predisposition to CPPD crystal deposition disease.40 Previous disk surgery may predispose to subsequent CPPD crystal deposition.81 CPPD crystals may be deposited in the ligamenturn flavum (Fig 18) and posterior longitudinal ligament, leading to myelopathy, cord compression, and spinal stenosis.81-83 The thoracic and lumbar regions are often affected, especially at the L2-3 disc leve1.84 MRI has demonstrated low signal intensity CPPD crystal deposits in the ligamenturn flavum.85 These deposits may be difficult to distinguish from the low signal intensity of the ligamenturn flavum itself. Discrete subchondral lucencies may be seen in the apophyseal joints-similar to those seen in the appendicular joints. CPPD crystals may accumulate about the odontoid process in the area of the transverse ligament, producing cord compression, bone erosion,* fracture, and atlantoaxial subluxation (Fig 30). CPPD crystal deposition disease should be considered in elderly patients with gradual onset of cervical myelopathy and severe degenerative changes of the upper cervical spine.86 CT can aid in the identification of calcification and the degree of cord compression. MR imaging is preferred in this situation, however, because it allows for a more complete evaluation of the spinal cord. Sacroiliac Joints. Sacroiliac joint abnormalities have been identified in approximately 50% of patients with CPPD crystal deposition disease.43 Abnormalities include subchondral erosions, reactive sclerosis and cyst formation, vacuum phenomena, and articular cartilage calcification (Fig 31). Calcification of the interosseous sacroiliac ligament also has been observed.87 Temporomandibular Joints. CPPD crystal deposi-

Curr Probl

Diagn

Radiol,

November/December

2000

tion disease has been reported in the temporomandibular joints. 88-90 Tumoral CPPD deposits in this area can mimic parotid tumors on clinical examination.62 Differential

Diagnosis

Conditions that can simulate CPPD crystal deposition disease radiographically include osteoarthritis, neuropathic osteoarthropathy, synovial osteochondromatosis, hydroxyapatite crystal deposition disease, septic arthritis, gout, osteonecrosis, ochronosis, and spondyloarthropathies. It is helpful to analyze clinical and laboratory data and to examine the radiographs for the presence of distinctive characteristics of CPPD crystal deposition disease. Radiographic features such as local calcification and chondrocalcinosis, large subchondral cyst-like lucenties, extensive subchondral sclerosis, collapse and fragmentation of joint surfaces, involvement of joints or components of joints that are not commonly affected by osteoarthritis, variable osteophyte formation, lack of erosion, and osseous debris aid in distinction of this disorder from primary osteoarthritis. Calcifications in hydroxyapatite crystal deposition disease (HADD) are more homogeneous or cloudlike, and chondrocalcinosis is rare. Tendinous calcification in HADD differs from the elongated calcification seen in CPPD crystal deposition disease. In the setting of severe structural joint abnormality, osseous density is usually preserved in neuropathic joint disease, whereas this may not be true in CPPD crystal deposition disease. Pain is usually mild or absent in the presence of neuropathic joint disease, unlike the neuropathic form of CPPD crystal deposition disease. The lack of osteopenia and erosion usually allows differentiation of this arthropathy from inflammatory arthritides such as rheumatoid arthritis and septic arthritis. In chronic cases, joint erosion may be severe, simulating rheumatoid arthritis. Radiologic findings of joint or periarticular calcification and distribution of the arthropathy in CPPD crystal deposition disease usually allow differentiation from these arthritides. However, because sepsis may coexist with crystal synovitis in 1% or 2% of cases,‘r Gram stain and culture of joint fluid should be undertaken, even if CPPD crystals are identitied on radiographs or in joint fluid. Distinguishing between CPPD crystal deposition disease and gout may be complicated by the occasional coexistence of these two arthropathies in the same joint or person. 92 The presence of “punched out” or

Curr Probl

Diagn

Radiol,

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2000

juxta-articular osseous erosion is useful for diagnosing gouty arthropathy. Lack of chondrocalcinosis in association with periarticular calcification may suggest other causes such as dystrophic calcification, metastatic calcification, or tumoral calcinosis. Conclusion CPPD crystal deposition disease is widespread in elderly persons and has various clinical presentations that can be confounding to clinicians. Underlying knowledge of the various imaging presentations of CPPD crystal deposition disease aids in a more accurate diagnosis. Further studies that focus on pathophysiology, epidemiology, and the relation of this disease to aging should improve our understanding of the cause of this disorder. REFERENCES 1. Zitnan D, Sitaj S. Mnoh opocetna familiarha kalcifikaaz artikularynch chrupiek. Bratislouske Lakarske Listy 1958; 38217. 2. Zitnan D, Sitaj S. Chondrocalcinosis articularis. Section I: clinical and radiological study. Ann Rheum Dis 1963;22: 142. 3. Revault PP, Vignon G, Lejeune E, et al. Diffuse articular chondrocalcinosis (apropos of six personal cases). J Med Lyon 1961;42:65-98. 4. Martel W, Champion CK, Thompson GR; Carter TL. A roentgenologically distinctive arthropathy in some patients with the pseudogout syndrome. Am J Roentgen01 1970; 109:587-605. 5. Steinbach LS, Resnick D. Calcium pyrophosphate dihydrate crystal deposition disease revisited. Radiology 1996;200: 1-9. 6. McCarty DJ, Hogan JM, Gatter RA, et al. Studies on pathological calcifications in human cartilage. I. Prevalence and types of crystal deposits in the menisci of two hundred-fifteen cadavers. J Bone Joint Surg 1966;48A:309. 7. McCarty DJ. Crystals and arthritis. Dis Mon 1994;40:25399. 8. Rivera-Sanfeliz G, Resnick D, Haghighi P, Wong W, Lanier T. Tophaceous pseudogout. Skeletal Radio1 1996;25:699-701. 9. O’Duffy JD. Calcium pyrophophate deposition disease. New York: 1998. p. 286. 10. Moskowitz RW. Diseases associated with the deposition of calcium pyrophosphate or hydroxyapatite. Philadelphia: 1983. D. 1337-54. 11. MitroGic DR, Stankovic A, Iriarte-Borda 0, et al. The prevalence of chondrocalcinosis in the human knee joint: an autopsy survey. J Rheumatol 1988;15:633. 12. Felson DT, Anderson JJ, Naimark A, et al. The prevalence of chondrocalcinosis in the elderly and its association with knee osteoarthritis: The Framingham study. J Rheumatol 1989;16: 1241. 13. Sanmarti R, Panella D, Brancos MA, et al. Prevalence of articular chondrocalcinosis in elderly subjects in a rural area of Catalonia. Ann Rheum Dis 1993;52:418. 14. Ryan LM, McCarty DJ. Calcium pyrophosphate crystal deposition disease, pseudogout, and articular chondrocalcinosis. Baltimore: 1997. p. 2103-125. 15. Jones AC, Chuck AJ, Arie EA, Green DJ, Doherty M.

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Gerster JC, Baud CA, Lagier R, Boussina I, Fallet GH. Tendon calcifications in chondrocalcinosis. A clinical, radiologic, histologic and crystallographic study. Arthritis Rheum 1977;20:717-22. 57. Foldes K, Lenchik L, Jaovisidha S, Clopton P, Sartoris DJ, Resnick D. Association of gastrocnemius tendon calcification with chondrocalcinosis of the knee. Skeletal Radio1 1996;25:621-4. 58. McCarty DJ, Haskin ME. The roentgenographic aspects of 56.

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2000

59. 60. 61. 62. 63. 64. 65. 66. 67. 68.

69. 70.

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