Intra-Articular Apatite Crystal Deposition

Ann Rheum Dis: first published as 10.1136/ard.42.Suppl_1.54 on 1 January 1983. Downloaded from

Ann Rheum Dis (1983), 42, Supplement p 54

Intra-articular apatite crystal deposition

H. RALPH SCHUMACHER,' P. VERGHESE CHERIAN,' ANTONIO J. REGINATO,1 THOMAS BARDIN,2 SUSAN ROTHFUSS1 From the 'University ofPennsylvania School ofMedicine, Philadelphia, USA and 2Clinique Rheumatologique, Hospital Lariboisiere, Paris, France

Introduction and specificity of most technicques have close to the 1 67:1 expected with well not been fully defined. Regiular light crystallised apatite. The role of apatite crystals in calcific microscopy may allow visualiisation of Transmission electron microscopy periarthritis is well recognised.1-5 For larger clumps of apatite crrystals as allows identification of the tiny thin many years, however, intra-articular glossy, slightly irregular globules from 50-250A diameter needles within the apatites were not thought to play any 2-10,um in diameter (Fig. 1). Only a clumps that are typical of apatite.' This part in joint disease. They were few of such aggregaltes are technique may be used on small identified in only a small percentage of birefringent.' Stains for calccium and amounts of fluid and also on either thin menisci examined grossly and by x-ray phosphorus such as Von Koissa's and sections or synovial fluid dried onto diffraction by McCarty et al. in 1966.6 alizarin red stains can hellp further formvar coated grids.11 Used on synovial In 1975-7 we7' and Dieppe et al.' identify these globules.' NWe have fluid the technique detects down using electron microscopy and examined the sensitivity of thie alizarin to at least 0-002 mg/ml of apatite and elemental analysis on joint fluids red stain and find that it ccan detect avoids possible artefacts of chemical found apatite crystals in various 0- 005 ,ug of synthetic apatite in 1 ml of fixation. Examination of thin sections situations including acute otherwise synovial fluid.' The techniqiue is still also allows demonstration of whether by copyright. unexplained arthritis. We review our not totally specific and is used only as a and by which cells crystal clumps are findings since that time. screening test. phagocytised. This may obviously be Scanning electron mic:roscopy important for the phlogistic Methods for crystal identification (SEM) can also identify clunips of the significance of the apatite. Elements same shape1" and allows electron may also be analysed as with SEM. Techniques used to identify apatite probe elemental analysis, whiich shows Electron diffraction patterns can also crystals in synovial fluids have varied not only whether calciium and be made for comparison with known in different series and may affect the phosphorus are present Ibut also standards, but the problems and value importance of the findings. Sensitivity whether their approximate rratios are of this have not yet been worked out. When large amounts of suspected apatite are present x-ray diffraction is http://ard.bmj.com/ generally accepted as the definitive method of analysis, although small E amounts of certain crystals may be missed when mixed with other predominant crystals. A semi- quantitative screening technique for apatite using 14C disodium

etidronate binding is also being on September 28, 2021 by guest. Protected studied.12 Intracellular crystals might be missed with this method. Infrared ,04| 1t spectrophotometry has been used to supplement findings with other .-- w. techniques1" and with the use of Fournier transform may allow ^.$ detection of small amounts of crystals mixed in with other predominant ones. 8.# '. ..F ..:.0 Apatite in joints Apatite has been described in knees, shoulders, hips, wrists, first carpometacarpal joints, meta- Fig. 1 Lightmicroscopical viewof irregularclumpsofapatite crystals (arrows) in carpophalangeal, proximal and synovial fluid. Note erythrocytes (E) and neutrophils (N) for size comparison. distal interphalangeal joints, and Ann Rheum Dis: first published as 10.1136/ard.42.Suppl_1.54 on 1 January 1983. Downloaded from

Intra-articular apatite crystal deposition Suppl p 55 metatarsophalangeal joints including the 1st.5 89 13 We have studied a total of 104 patients in whom apatite was .5.. found by transmission electron microscopy and find a similar distribution of joints containing these crystals. Cases reported have generally been from studies of specific diseases or selected by referral so the incidence of identifiable apatite in the general population remains unclear. Women seem to be affected more often than men,5 and we know of no reports in children except in association with collagen disease. Our '9....0

study included 58 women and 46 men; jwA-A there was a high incidence of elderly R patients because we included 44 patients from a study of osteoarthritis, the youngest patient was 36 years old.

CLINICAL PRESENTATIONS Otherwise unexplained acute inflammatory arthritis with joint effusions containing apatite has been

reported by Fam et al., Dieppe et al., by copyright. and our group at knees, wrists, hips, proximal interphalangeal joints, metacarpophalangeal joints, and first metatarsophalangeal joints' 89 and Fig. 2 A clump oftiny crystals proved to be apatite by elemental analysis lie in a may well occasionally occur at any vacuole ofa synovial fluid mononuclear cell. Electron micrograph x20 000 joints where crystals can deposit. (original magnification). Some patients have had multiple attacks and have also occasionally had calcific periarthritis. Attacks may resolve without treatment; some TEM Ali found apatite more often in In patients with clinical progress to chronic erosive arthritis."3 osteoarthritic than other cartilages but osteoarthritis the severity of Synovial fluid leucocyte counts in did not describe incidence.'7 Even in radiographic changes of osteoarthritis http://ard.bmj.com/ clinically acutely inflamed joints have osteoarthritis with 'non-inflammatory' tends to correlate with the incidence of ranged from 1 8-84 x 109/P5 9 joint effusions apatite has been apatite deposition. Neutrophils have ranged from 27%YO to phagocytised by synovial lining cells 90% with a predominance in acute that might release proteases and Apatite associated with other diseases cases. Crystals may be seen to be collagenase and be a major factor in phagocytised by synovial fluid progressive joint damage."3 Apatite crystals have been found in a neutrophils and mononuclear cells high percentage of specimens of (Fig. 2).8 RADIOGRAPHIC FINDINGS synovial fluid or cartilage from on September 28, 2021 by guest. Protected Most recent studies have also Joints with acute or subacute patients known also to have CPPD identified apatite crystals in some joint apatite-associated arthritis may show deposition. 420-22 Either or both effusions without any dramatic calcification in the synovial space (Fig. crystals may be phagocytosed; in our evidence of inflammation.8 9 18 14 15 3).' The linear cartilage or meniscal still limited experience CPPD seems Many such joints have had calcification seen with CPPD is not more often to be intracellular. osteoarthritis, but the real incidence of expected. Some x-ray films show no Other diseases that have been apatite deposition in osteoarthritis and calcification despite later associated with clinically significant how often it occurs early in still grossly demonstration of large amounts of apatite arthritis include scleroderma, normal cartilage is not yet known. We apatite. In fact, only 21 of our 104 dermatomyositis, and systemic lupus found apatite in 44 of 100 patients had obviousx-ray evidence of erythematosus" ; renal failure treated osteoarthritic effusions after calcification. Patients may also have by haemodialysis;l 19 and possibly high examining just one grid on each by periarticular calcifications at the dose vitamin D treatment.26 Apatite transmission EM.'5 Dieppe et al. symptomatic site or elsewhere. also occurs in other joint diseases, found apatite in 9 out of 34 unselected Erosive arthritis may develop'" '8 and presumably as a secondary osteoarthritic fluids with scanning changes of osteoarthritis may be complication. We found apatite in 8 electron microscopy (SEM).6 Using present.'4 out of 32 effusions from joints with Ann Rheum Dis: first published as 10.1136/ard.42.Suppl_1.54 on 1 January 1983. Downloaded from

Suppl p 56 Annals ofthe Rheumatic Diseases Characteristics of crystals It is impressive that there is tremendous morphological variation among apparent apatites we have found in joints. Crystals may be almost punctate, (Fig. 2), rods or thicker 'boat-like' structures, (Fig. 4) or long needles (Fig. 5); they may be densely or loosely packed, and larger crystals may have the suggestion of an internal structure at high magnification. Crystals may be rare or profuse enough to make the fluid milky. Rare clumps may obviously have different clinical significance than massive amounts. Crystals are frequently phagocytosed (Fig. 6) but seem most often to be ingested by mononuclear cells rather than polymorphonuclear neutrophils. Elemental analysis also shows some variation with some apparent apatite having Ca:P ratios well below the expected 1 67:1, suggesting the presence of some amorphous or poorly crystallised salts. Substitution of chloride and carbonate by copyright. in apatite also varies. As yet we know of no good correlation of elemental analysis findings with crystal morphology. Apatite was most often detected in synovial fluid because of its accessibility and from knees rather than other joints for the same reason. Arms, including finger joints, wrists, Fig. 3 X-ray films ofhand, showing apatite deposits best in the joint space ofthe elbows, and shoulders seemed fifth metacarpophalangeal joint and the capsule ofthe second involved more often than the legs in http://ard.bmj.com/ metacarpophalangeal joint. This patient had a history of recurrent acute arthritis patients with collagen-vascular disease that evolved into erosive arthritis. or those undergoing renal dialysis. Apatite was seen in surgical specimens rheumatoid arthritis; the crystals rather than by the underlying of cartilage either as round clumps correlated with the severity of rheumatoid arthritis. Table 1 shows near to chondrocytes (but not clearly secondary osteoarthritis.27 In certain diagnoses other than osteoarthritis in in matrix vesicles) or as irregular cases acute dramatic inflammation in a our 104 patients with apatite masses on the surface or in the single joint may be induced by deposition. crystals interstitium. Apatite in synovium was on September 28, 2021 by guest. Protected frequently phagocytosed or enfolded Table 1 Associated diseases other than osteoarthritis in 104 patients with by synovial cell processes. intra-articular apatite crystals Diseases Mechanisms involved in apatite No ofpatients deposition disease Dermatomyositis, scleroderma 6 Renal failure on dialysis 10 The ability of apatite to induce acute Oxalate deposition 1 inflammation in joints has been shown Hypothyroidism 3 by intra-articular injection into the Haemochromatosis 3 knees of dogs using the same model as Osteochondromatosis 1 that used for urate and CPPD crystals.8 Acromegaly 2 has also CPPD deposition 22 Apatite produced Gout 5 inflammation at other sites-for Rheumatoid or psoriatic arthritis 10 example, the pleural space and Temporal arteritis with aseptic necrosis I subcutaneous tissue'°-after experimental injection. Apatite is not Ann Rheum Dis: first published as 10.1136/ard.42.Suppl_1.54 on 1 January 1983. Downloaded from

Intra-articular apatite crystal deposition Suppl p 57 possibility that other materials, including fibronectin, osteonectin enzymes, and complement, are present should also be considered. As previously sug- gested with urate crystals,' substances adhering to crystals could encourage I or inhibit inflammation. Effects could even vary depending on other cellular I. .. .;, N 1"4 ".. ... and humoral aspects of the joint. :"g.- ..k' ;t , ..J. Complement may be activated by apatite as well as by other crystals.3' Apatite almost certainly appears in joints by different mehanisms. In some 411V cases (as with CPPD) it is thought to be a result of degenerative changes in cartilage and to deposit first in cartilage.'7 In other examples, especially when associated with migratory calcific periarthritis at other sites, it probably deposits outside cartilage due to the still unknown systemic factors that seem to cause most such calcific periarthritis. Phosphate excess or other features of renal failure and haemodialysis seem to contribute to some cases.'9 Serum and synovial fluid calcium and by copyright. Fig. 4 Rod and 'boat-like' apatite crystals. Some foamy internal strructur canbe phosphate concentrations have been seen at high magnification. Electron micrograph x125 000 (original normal in most cases. Occasionally magnification). apatite is seen to have risen from fragments of bone released into severely destroyed joints. Apatite deposition in articular cartilage occurs spontaneously in aging rabbits or after administration of vitamin D; synovial calcification with apatite can be induced by

intra-articular calciphylaxis.3' In http://ard.bmj.com/ neither of these established types of experimental apatite calcification has acute inflammation occurred. Long term studies are still needed to determine ifosteoarthritis evolves or if various modifications can produce attacks of acute arthritis.

Treatment on September 28, 2021 by guest. Protected Acute inflammation associated with apatite deposition generally seems to

Fig. 5 Long needle-like apatite crystals from joint fluid stained w ith ferritin respond to treatment with conjugated antibody to IgG demonstrating binding of this immuno)globulin indomethacin, other non-steroidal or has labelled by ferritin particles (arrows) to clump. Electron micro graj ph x80 000 agents, colchicine.' Aspirin been ineffective in some cases. (original magnification). Intra-articular depot corticosteroids have also appeared to be helpful.' We always associated with detectable with most clumps of crystals have no personal experience with inflammation (the same is true of urate embedded in synovium or superficial measures to prevent or decrease and CPPD28 29) and the reasons for this cartilage. Prelimina ry immuno- apatite deposition. Disodium require study. electron microscopical studies in our etidronate has been reported to In TEM sections finely granular laboratory show that immuno- decrease calcinosis but with chronic material is generally associated with globulins are at least oine component use may also effect bone the synovial fluid crystals (Fig. 6)8 and of this granular materia (Fig. 5). The mineralisation.32 In patients with Ann Rheum Dis: first published as 10.1136/ard.42.Suppl_1.54 on 1 January 1983. Downloaded from

Suppl p 58 Annals of the Rheumcatic Diseases

our laboratory and appreciate the careful typing of Miss Mary Ellen Maguire.

References 1 Codman E A. The shloul(ler. Boston: Thomas Todd, 1934. ne 2 Pinals R S, Short C L. Calcific %H:n periarthritis involving multiple sites. Arthritis Rheurn 1966; 9: 566-74. 3 McCarty D J, Gatter R A. Recurrent acute inflammation associated with focal apatite crystal deposition.Arthritis Rheum 1966; 9: 804-19. 4 Amor B, Cherot A, Delbarre F. Le rhumatisme a hydroxyapatite. Rev Rhum Mal Osteoartic 1977; 44: 301-8. 5 Fam A G, Pritzker K P H, Stein J L, Houpt J B, Little A H. Apatite associated arthropathy: a clinical study of 14 cases and 2 patients with calcific bursitis. J Rheuramtol 1979; 6: 461-71. 6 McCarty D J, Hogan J M, Gatter R A, Grossman M. Studies or pathological calcifications in human cartilage. 1. Pre- valence and types of crystal deposits in the menisci of 215 cadavera. J Bonie Joinit Surg [Am] 1966; 48: 309-25. 7 Schumacher H R. Pathology of the

svnovial membrane in gout. Light and by copyright. electron microscopic studies. Interpretation of crystals in electron micrographs. Arthritis Rheuoti 1975; 18: 771-82. 8 Schumacher H R, Somlvo A P. Tse R L, Fig. 6 Apatite crystals embedded iet electron dense material in a vacuole of a Maurer K. Arthritis associated with synovial fluid mononuclear cell. Electron micrograph x32 000 (original apatite crystals. Anltiterni Med 1 977; tnagnification). 87: 411-6. 9 Paul H, Reginato A J. Schumacher H R. Alizarin red S-staining as a screening abnormal calcium or phosphorus usually in association with CPPD."4 test to detect calcium compounds in metabolism as, for example, occurs in Whitlockite and octacalcium ssnovial fluid. Arthritis Rheuri (in http://ard.bmj.com/ many of those with renal failure, better phosphate may also occur in diseased press). joints along with apatite. {' 1(1 Dieppe P A. Crocker P, Huskissonl E C, control of phosphorus concentrations Willoughby D A. Apatite deposition we have found calcium may decrease apatite deposits. Some Recently, disease. A new athropathy. ILaicet calcinosis in or around joints has also oxalate crystals in synovial effusions in 1976; i: 266-9. been reported to resolve three patients undergoing haemo- 11 Paul H, Reginato A J, Schumacher H R. spontaneously. In one patient of ours dialysis for chronic renal failure.37 In Morphological characteristics of with a scleroderma-like disease apatite one patient x-ray films showed finger monosodium urate: a transmission deposits in finger joints resolved when calcifications similar to those seen with electron microscopic study of intact stitfened with apatite and knee chondrocalcinosis natural and synthetic crystals. Ant on September 28, 2021 by guest. Protected joints gradually Dis like that seen with CPPD deposition. Rheum (in press). progressive skin disease .2 12 Halverson P B, McCarty D J. Indomethacin was thought to decrease Detailed analyses at necropsy revealed Identification of hydroxyapatite crystals para-articular ectopic ossification in massive oxalate deposits and no in synovial fluid.Arthritis Rheutn 1979; three cases after total hip CPPD. The list of crystals identifiable 22: 389-95. arthroplasty.33 Neither this nor other in joints is almost certainly not yet 1 3 Schumacher H R, Miller J L, Ludivico possible ways of decreasing calcinosis complete. We and others have seen C, Jessar R A. Erosive arthritis associ- have been adequately and other unidentified birefringent or ated with apatite crystal deposition. systematically evaluated. electron dense material that is still Arthritis Rheuni 1981; 24: 31-7. under evaluation. 14 Schumacher H R, Gibilisco P, Reginato Other calcium-containing crystals A J, Cherian V, Gordon G V. Supported in part by grants from the Implications of crvstal deposition in Veterans Administration. National osteoarthritis. J Rheuttatol (in press). Other calcium-containing crystals Institutes of Health (1-R21-AG 02815-01), 15 Schumacher H R, Gordon G. Paul H, have been described in intra-articular McCabe Foundation, and Barsumian Fund. Reginato A, Villanueva T, Cherian V, sites. Brushite (CaHPO4 2HlO) has We thank Miss Gilda Clayburne, Miss Gibilisco P. Osteoarthritis, crystal been reported in small amounts of Marie Sieck, and Mrs Susan Rothfuss for deposition and inflammation. Semin uncertain clinical importance and excellent technical help on the work from Arthritis Rheum 1981; 11: 116-9. Ann Rheum Dis: first published as 10.1136/ard.42.Suppl_1.54 on 1 January 1983. Downloaded from

Intra-articular apatite crystal deposition Suppl p 59

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the degenerative arthropathy of 559-60. octacalcium phosphate and tricalcium by copyright. hemochromatosis. Arthritis Rheum (in 29 Schumacher H R. Pathogenesis of phosphate [Abstract]. Clinical Research press). crystal-induced arthritis. Clinics in 1982; 30: 807. 22 Martel W, McCarter D K, Solsky M A, Rheumatic Diseases 1977; 3: 105-31. 37 Hoffmnan G, Schumacher H R, Paul H, et al. Further observations on the 30 Hasselbacher P. C3 activation by et al. Calcium oxalate microcrystalline arthropathy of calcium pyrophosphate monosodium urate monohydrate and associated arthritis in end stage renal crystal deposition disease. Radiology other crystalline material. Arthritis disease. Ann Intern Med 1982; 97: 1981; 141: 1-15. Rheum 1979; 22: 571-8. 36-42. http://ard.bmj.com/ on September 28, 2021 by guest. Protected