The
Journal of Pathology Vol. 123 No. 1 MIXED CRYSTAL DEPOSITION I N AN OSTEOARTHRITIC JOINT D. V. DOYLE,P. A. DIEPPE,P. R. CROCKER, K. IBE, AND D. A. WILLOUGHBY Department of Experimental Pathology and Rheumatology, St Bartholomew’s Hospital, London E e l ; and Jeol ( U K ) Ltd, Colindale
PLATE I DEPOSITION of calcium pyrophosphate dihydrate in articular cartilage is common. The prevalence in osteoarthritis of chondrocalcinosis, the radiological hallmark of pyrophosphate deposition, is five per cent and is associated with a number of different clinical presentations (McCarty, 1976). Recently hydroxyapatite crystals have been identified in the joints of some patients with osteoarthritis (Dieppe et al, 1976). The two conditions have not been described together. In this paper a patient with osteoarthritis is described, from whose joint a mixture of both pyrophosphate and hydroxyapatite crystals were isolated. CASEHISTORY An otherwise fit 72-yr-old woman was admitted with a 12-yr history of increasing pain in the right shoulder, in the absence of any apparent predisposing cause. Examination revealed gross, painful, concentric restriction of shoulder movements, and X-rays showed advanced osteoarthritic changes with some soft tissue calcification in and around the joint. A total shoulder replacement was carried out, and the excised tissues examined. METHOD Tissue samples were obtained at operation, and prepared for routine histological examination. In addition, analytical electron microscopy was carried out on the samples, using similar techniques t o those described previously (Crocker et al., 1977). The apparatus used was the “ Jeol TEMSCAN ” Analytical System. Confirmation of the nature of the mineral deposits was obtained by examining them in a Perkin-Elmer 577 infra-red spectrophotometer, and comparing spectra with those of known controls. Received 10 Jan. 1977; accepted 6 Feb. 1977. 1. PATH.-VOL.
123 (1977)
1
A
2
DOYLE, DIEPPE, CROCKER, IBE AND WILLOUGHBY
RESULTS Histology. Routine histology showed advanced destruction of articular cartilages, villous hypertrophy, thickening and patchy mononuclear cell infiltration of the synovium and fibrous thickening of the capsule. Discrete deposits of calcified material could be seen with the naked eye, and these were dissected out for analysis from the synovial membrane. Crystal analysis. Viewed in the electron microscope, the calcified areas were found to contain two different types of crystal. Small hexagonal crystals (approximately 0.5 microns long) were analysed and found to have a phosphorus/calcium ratio of 0.41 (fig. 1). Larger monoclinic and triclinic crystals were identified and found to have a phosphorus/calcium ratio of 0.77 (fig. 2). These ratios corresponded well to those of pure crystals of hydroxyapatite and calcium pyrophosphate dihydrate respectively, when examined in identical conditions. The presence of a mixture of two different minerals was confirmed by infrared spectrophotometry. The pattern obtained was identical to that of a mixture of hydroxyapatite and calcium pyrophosphate dihydrate in the ratio 3 : 2 (fig. 3). DISCUSSION In the case presented, a woman with osteoarthritis of the shoulder, analytical elecron microscopy revealed the presence in the joint tissue of two types of calcium phosphate crystal, with different morphology and elemental ratios. Comparison with standard preparations indicated that the crystals were hydroxyapatite and calcium pyrophosphate, and this was supported by the data from infra-red spectrophotometry. The infra-red analysis permitted semi-quantitative estimation of the amounts of the two crystals in this case. It has been thought that the conditions necessary for calcium pyrophosphate dihydrate and hydroxyapatite crystal deposition were mutually exclusive. Howell (1975) has shown that the phosphatase content of cartilage with deposits of calcium pyrophosphate is very low. Conversely, a high level of cartilage alkaline phosphatase favours hydroxyapatite deposition. The occurrence of the two types of crystal has been suspected in patients with radiological chondrocalcinosis and synovial osteochondromatosis. Okazaki et al. (1976), in reviewing 18 patients with calcium pyrophosphate deposits in the menisci of the knee joint, found one patient with associated osteochondromatosis. X-ray diffraction studies on the synovial lesion showed the crystals to be hydroxyapatite. Altman (1976) in an arthroscopic study of nine patients with calcium pyrophosphate deposition disease as defined by McCarty (1972) found that four of the nine had associated osteochondromatosis. Analysis of the synovial crystals was not performed. It cannot be presumed that all synovial osteochondromatosis deposits are made up of hydroxyapatite crystals as Ellman et al. (1975) have shown that in two cases of calcium pyrophosphate deposition with associated radiological osteochondromatosis the synovial deposits were in fact calcium pyrophosphate dihydrate crystals.
CR YSTALS IN OSTEOARTHRlTIS
3
FIG. 3.-Infra-red spectra of pure hydroxyapatite and calcium pyrophosphate dihydrate (top), a mixture of the two salts in the ratio 3 : 2 (middle), and the calcified material from the patient’s synovium (bottom). The patient sample has a spectrum very similar to that of a mixture of the two salts. (Wavenumber 1400-700 CM-1.)
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DOYLE, DIEPPE, CROCKER, IBE A N D WILLOUGHBY
In the case reported the morphological, elemental and chemical analyses confirm that calcium pyrophosphate dihydrate and hydroxyapatite may be deposited in close proximity in the same tissue in a patient with clinical and radiological evidence of osteoarthritis. This patient did not show any evidence of synovial osteochondromatosis. It is well recognised that calcium pyrophosphate deposition is associated with ageing and degenerative joint disease. Similarly, hydroxyapatite deposition is associated with some cases of degenerative arthritis. The occurrence of both crystals together in a case of advanced osteoarthritis would support the hypothesis that crystal deposition may be part of a final common pathway in the development of osteoarthritis. SUMMARY
The case of a 72-yr-old woman with osteoarthritis of the shoulder, is described. A mixture of crystals of hydroxyapatite and calcium pyrophosphate djhydrate was identified in the joint tissues using analytical electron microscopy and infra-red spectroscopy. We are grateful for the financial support of the Arthritis and Rheumatism Council, the European Biological Research Association, the Wellcome Foundation and the Joint Research Board of St Bartholomew’s Hospital. We would like to thank JEOL (UK) Ltd for allowing us to use their electron microscope, and Mr A. W. F. Lettin for allowing us to study this case. REFERENCES ALTMAN, R. 1976. ‘Arthroscopic findings of the knee in patients with pseudogout. Arthritis Rheum., 19, No. 3 (supplement), 286. CROCKER, P., DIEPPE,P. A., TYLER,G., CHAPMAN, s. K., AND WILLOUGHBY, D. A. 1977. The identification of particulate matter is biological tissues and fluids. J. Path., 121, 37. DIEPPE,P. A., HUSKISSON, E. C., CROCKER, P., AND WILLOUGHBY, D. A. 1976. Apatite deposition disease: a new arthropathy. Lancet, 1, 226. ELLMAN,M. H., KRIEGER, M. I., AND BROWN,N. 1975. Pseudogout mimicking synovial chondromatosis. J. Bone and Joint Surgery, 57A,863-865. HOWELL,D. S., MUNIZ,O., PITA,J. C., AND ARSENIS, C. 1976. Preliminary observations on phosphatases in articular cartilages. Arthritis. Rheum., 19, No. 3 (supplement) 495. MCCARTY, D. J . 1972. Pseudogout (articular chondrocalcinosis). In Arthritis and allied conditions, 8th ed., edited by J. L. Hollander and D. J. McCarty, Lea and Febiger, Philadelphia, p. 1146. MCCARTY,D. J. 1976. Calcium pyrophosphate dihydrate crystal deposition disease. Arthritis Rheum., 19, No. 3 (supplement), 275. OKAZAKI, T., SAITO,T., MITOMO, T., AND SIOTA, Y. 1976. Clinical observations and chemical analysis in patients with pseudogout. Arthritis Rheum., 19, No. 3 (supplement), 293.
DOYLE,DIEPPE, CROCKER, IREAND WILLOUCHBY
PLATE I
CRYSTALS IN OSTEOARTHRITIS
FIG.1.-Scanning
electron micrograph of a n area of the synovial membrane showing small hexagonal crystals of hydroxyapatite. x 15,000.
FIG.2.-Scanning electron micrograph from an adjacent area to that shown in fig. 1. Numerous monoclinic and triclinic crystals of calcium pyrophosphate dihydrate can be seen. x 15,000.
Journal of Pathology Vol. 123 No. 1 MIXED CRYSTAL DEPOSITION I N AN OSTEOARTHRITIC JOINT D. V. DOYLE,P. A. DIEPPE,P. R. CROCKER, K. IBE, AND D. A. WILLOUGHBY Department of Experimental Pathology and Rheumatology, St Bartholomew’s Hospital, London E e l ; and Jeol ( U K ) Ltd, Colindale
PLATE I DEPOSITION of calcium pyrophosphate dihydrate in articular cartilage is common. The prevalence in osteoarthritis of chondrocalcinosis, the radiological hallmark of pyrophosphate deposition, is five per cent and is associated with a number of different clinical presentations (McCarty, 1976). Recently hydroxyapatite crystals have been identified in the joints of some patients with osteoarthritis (Dieppe et al, 1976). The two conditions have not been described together. In this paper a patient with osteoarthritis is described, from whose joint a mixture of both pyrophosphate and hydroxyapatite crystals were isolated. CASEHISTORY An otherwise fit 72-yr-old woman was admitted with a 12-yr history of increasing pain in the right shoulder, in the absence of any apparent predisposing cause. Examination revealed gross, painful, concentric restriction of shoulder movements, and X-rays showed advanced osteoarthritic changes with some soft tissue calcification in and around the joint. A total shoulder replacement was carried out, and the excised tissues examined. METHOD Tissue samples were obtained at operation, and prepared for routine histological examination. In addition, analytical electron microscopy was carried out on the samples, using similar techniques t o those described previously (Crocker et al., 1977). The apparatus used was the “ Jeol TEMSCAN ” Analytical System. Confirmation of the nature of the mineral deposits was obtained by examining them in a Perkin-Elmer 577 infra-red spectrophotometer, and comparing spectra with those of known controls. Received 10 Jan. 1977; accepted 6 Feb. 1977. 1. PATH.-VOL.
123 (1977)
1
A
2
DOYLE, DIEPPE, CROCKER, IBE AND WILLOUGHBY
RESULTS Histology. Routine histology showed advanced destruction of articular cartilages, villous hypertrophy, thickening and patchy mononuclear cell infiltration of the synovium and fibrous thickening of the capsule. Discrete deposits of calcified material could be seen with the naked eye, and these were dissected out for analysis from the synovial membrane. Crystal analysis. Viewed in the electron microscope, the calcified areas were found to contain two different types of crystal. Small hexagonal crystals (approximately 0.5 microns long) were analysed and found to have a phosphorus/calcium ratio of 0.41 (fig. 1). Larger monoclinic and triclinic crystals were identified and found to have a phosphorus/calcium ratio of 0.77 (fig. 2). These ratios corresponded well to those of pure crystals of hydroxyapatite and calcium pyrophosphate dihydrate respectively, when examined in identical conditions. The presence of a mixture of two different minerals was confirmed by infrared spectrophotometry. The pattern obtained was identical to that of a mixture of hydroxyapatite and calcium pyrophosphate dihydrate in the ratio 3 : 2 (fig. 3). DISCUSSION In the case presented, a woman with osteoarthritis of the shoulder, analytical elecron microscopy revealed the presence in the joint tissue of two types of calcium phosphate crystal, with different morphology and elemental ratios. Comparison with standard preparations indicated that the crystals were hydroxyapatite and calcium pyrophosphate, and this was supported by the data from infra-red spectrophotometry. The infra-red analysis permitted semi-quantitative estimation of the amounts of the two crystals in this case. It has been thought that the conditions necessary for calcium pyrophosphate dihydrate and hydroxyapatite crystal deposition were mutually exclusive. Howell (1975) has shown that the phosphatase content of cartilage with deposits of calcium pyrophosphate is very low. Conversely, a high level of cartilage alkaline phosphatase favours hydroxyapatite deposition. The occurrence of the two types of crystal has been suspected in patients with radiological chondrocalcinosis and synovial osteochondromatosis. Okazaki et al. (1976), in reviewing 18 patients with calcium pyrophosphate deposits in the menisci of the knee joint, found one patient with associated osteochondromatosis. X-ray diffraction studies on the synovial lesion showed the crystals to be hydroxyapatite. Altman (1976) in an arthroscopic study of nine patients with calcium pyrophosphate deposition disease as defined by McCarty (1972) found that four of the nine had associated osteochondromatosis. Analysis of the synovial crystals was not performed. It cannot be presumed that all synovial osteochondromatosis deposits are made up of hydroxyapatite crystals as Ellman et al. (1975) have shown that in two cases of calcium pyrophosphate deposition with associated radiological osteochondromatosis the synovial deposits were in fact calcium pyrophosphate dihydrate crystals.
CR YSTALS IN OSTEOARTHRlTIS
3
FIG. 3.-Infra-red spectra of pure hydroxyapatite and calcium pyrophosphate dihydrate (top), a mixture of the two salts in the ratio 3 : 2 (middle), and the calcified material from the patient’s synovium (bottom). The patient sample has a spectrum very similar to that of a mixture of the two salts. (Wavenumber 1400-700 CM-1.)
4
DOYLE, DIEPPE, CROCKER, IBE A N D WILLOUGHBY
In the case reported the morphological, elemental and chemical analyses confirm that calcium pyrophosphate dihydrate and hydroxyapatite may be deposited in close proximity in the same tissue in a patient with clinical and radiological evidence of osteoarthritis. This patient did not show any evidence of synovial osteochondromatosis. It is well recognised that calcium pyrophosphate deposition is associated with ageing and degenerative joint disease. Similarly, hydroxyapatite deposition is associated with some cases of degenerative arthritis. The occurrence of both crystals together in a case of advanced osteoarthritis would support the hypothesis that crystal deposition may be part of a final common pathway in the development of osteoarthritis. SUMMARY
The case of a 72-yr-old woman with osteoarthritis of the shoulder, is described. A mixture of crystals of hydroxyapatite and calcium pyrophosphate djhydrate was identified in the joint tissues using analytical electron microscopy and infra-red spectroscopy. We are grateful for the financial support of the Arthritis and Rheumatism Council, the European Biological Research Association, the Wellcome Foundation and the Joint Research Board of St Bartholomew’s Hospital. We would like to thank JEOL (UK) Ltd for allowing us to use their electron microscope, and Mr A. W. F. Lettin for allowing us to study this case. REFERENCES ALTMAN, R. 1976. ‘Arthroscopic findings of the knee in patients with pseudogout. Arthritis Rheum., 19, No. 3 (supplement), 286. CROCKER, P., DIEPPE,P. A., TYLER,G., CHAPMAN, s. K., AND WILLOUGHBY, D. A. 1977. The identification of particulate matter is biological tissues and fluids. J. Path., 121, 37. DIEPPE,P. A., HUSKISSON, E. C., CROCKER, P., AND WILLOUGHBY, D. A. 1976. Apatite deposition disease: a new arthropathy. Lancet, 1, 226. ELLMAN,M. H., KRIEGER, M. I., AND BROWN,N. 1975. Pseudogout mimicking synovial chondromatosis. J. Bone and Joint Surgery, 57A,863-865. HOWELL,D. S., MUNIZ,O., PITA,J. C., AND ARSENIS, C. 1976. Preliminary observations on phosphatases in articular cartilages. Arthritis. Rheum., 19, No. 3 (supplement) 495. MCCARTY, D. J . 1972. Pseudogout (articular chondrocalcinosis). In Arthritis and allied conditions, 8th ed., edited by J. L. Hollander and D. J. McCarty, Lea and Febiger, Philadelphia, p. 1146. MCCARTY,D. J. 1976. Calcium pyrophosphate dihydrate crystal deposition disease. Arthritis Rheum., 19, No. 3 (supplement), 275. OKAZAKI, T., SAITO,T., MITOMO, T., AND SIOTA, Y. 1976. Clinical observations and chemical analysis in patients with pseudogout. Arthritis Rheum., 19, No. 3 (supplement), 293.
DOYLE,DIEPPE, CROCKER, IREAND WILLOUCHBY
PLATE I
CRYSTALS IN OSTEOARTHRITIS
FIG.1.-Scanning
electron micrograph of a n area of the synovial membrane showing small hexagonal crystals of hydroxyapatite. x 15,000.
FIG.2.-Scanning electron micrograph from an adjacent area to that shown in fig. 1. Numerous monoclinic and triclinic crystals of calcium pyrophosphate dihydrate can be seen. x 15,000.
