Hydroxyapatite deposition in osteoarthritic articular cartilage of the proximal femoral head

Objective. To identify the morphology of a mineral-forming fraction of adult porcine hyaline articular cartilage digest and characterize the mineral it forms.Methods. Electron microscopy, Fourier transform infrared (FTIR) spectroscopy, x-ray microanalysis, compensated polarized light microscopy, and biochemical studies including 14C-labeled UDPG pyrophosphohydrolase radiometric assay.Results. plate cartilage matrix vesicles and formed mineral after only 24 hours in physiologic salt solution containing 1 mM ATP. The mineral contained inorganic pyrophosphate, 95% of which derived from ATP, and phosphate, 93% of which derived from inorganic phosphate in the medium. The FTIR spectrum of this mineral closely resembled the spectrum of standard calcium pyrophosphate dihydrate (CPPD) crystals. Compensated polarized light microscopy showed positively birefringent, rod-shaped crystals morphologically identical to CPPD. Ca:P ratios, defined by energy-dispersive microanalysis, were also consistent with CPPD.Conclusion. The articular cartilage vesicle fraction of porcine hyaline cartilage is capable of generating mineral that strongly resembles CPPD.Calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate crystals occur in articular cartilage and synovial fluid of patients with diverse arthropathies (1-3). Both crystal types may initiate or amplify articular tissue destruction ( 4 3 , but the source of these crystals has not been precisely identified. A sedimentable fraction of adult porcine articular cartilage digest which supports ATP-enhanced calcium deposition under physiologic ionic conditions has been demonstrated (6). We sought to characterize the morphology of this fraction by electron microscopy for comparison with a similar mineralizing fraction of epiphyseal growth plate matrix vesicles (7,8). We then characterized the mineral produced by this fraction, comparing it with crystals observed in human articular diseases. We report that a vesicle-containing fraction of articular cartilage digest produces both calcium phosphate and calcium pyrophosphate mineral in

Section: Methodssupporting

confidence: 62%

Section: Methodsmentioning

confidence: 99%

Articular Cartilage Vesicles Generate Calcium Pyrophosphate Dihydrate‐Like Crystals in Vitro

Derfus

Rachow

Mandel

et al. 1992

“…Characteristically, CPPD is positively but weakly birefringent, brushite is positively but strongly birefringent (30), and HA is too small to impart detectable birefringence. More definitive x-ray or electron diffraction analyses have occasionally disclosed various proportions of brushite (14) or HA (31) in the microcysts. The recent report by Ohira and Ishikawa (31) was based on energy dispersion analysis of x-rays.…”

Section: Resultsmentioning

confidence: 99%

Chondrocalcinosis in surgically resected joints

Sokoloff

Varma

1988

To investigate the association between chondrocalcinosis (CC) and osteoarthritis (OA), 338 joint specimens were examined histologically (55 knees and 84 hips surgically resected because of idiopathic OA, 106 control knees obtained postmortem, and 93 fractured hips). The risk for CC in the OA knees was sixfold that of the ageand sex-adjusted control sections. CC occurred much less frequently in the hip than in the knee; the association with OA was less clear-cut. It was not possible to resolve by statistical analysis which of the two pathological processes was the horse and which was the cart.Many published reports address the coexistence of chondrocalcinosis (CC) and osteoarthritis (OA), but there is much controversy about the frequency and significance of the association (1-8). Determining the relationship between the two processes is complicated by the fact that each lesion occurs with a certain frequency in the absence of the other, and both are related to age. The principal calcinotic deposits found are those of calcium pyrophosphate dihydrate (CPPD) crystals. Various concepts about the association of CC and OA can be resolved into 5 categories, as follows: 1) There is no relationship between CC and OA (2,3,9); 2) CPPD crystal deposi-

“…Most of the previously reported ultrastructural descriptions of CPPD deposition disease did not identify any direct relationship of the CPPD crystals with tissue matrix components such as collagen or matrix vesicles (17,(20)(21)(22)(23)(24)(25)(26). These matrix structures are thought to play a role in hydroxyapatite mineralization (30,3 l), although controversy about the relative roles of these components continues in different reports (32,33).…”

Section: Discussionmentioning

confidence: 99%

Calcium pyrophosphate dihydrate crystal deposition in synovium. relationship to collagen fibers and chondrometaplasia

Beutler

Rothfuss

Clayburne

et al. 1993

Objective. Reasons for apparent primary deposition of calcium pyrophosphate dihydrate (CPPD) crystals in some synovial membranes have not been systematically examined. We undertook the present study to investigate for and compare possible cellular and matrix factors related to the presence of these crystals in synovium and cartilage.Methods. Ten synovial membrane specimens and 6 cartilage specimens were obtained at the time of joint surgery from 10 patients with CPPD crystal deposition disease, for light microscopic (LM) and electron microscopic (EM) studies.Results. In all synovial and cartilage specimens, we found many of the small CPPD crystals aligned on or in parallel to collagen fibers, as seen by EM. In 9 of the Submitted for publication September 9, 1992; accepted in revised form December 1. 1992. 10 crystal-containing synovia, we found foci of chondrometaplasia adjacent to CPPD, by LM. In 7 of the synovia, including the one without LM evidence of chondrometaplasia, we observed the presence of chondrocytelike cells by EM. We did not note any predictable relationship between the crystals and matrix vesicles, either in synovium or in cartilage.Conclusion. Our EM findings provide evidence of the relationship of small CPPD-like crystals, presumably early forms, to collagen fibers both in synovium and in cartilage. By LM and EM, we also demonstrate evidence of a close association between chondrometaplasia and CPPD deposits in synovium. We suggest that chondrometaplasia might be responsible for synovial CPPD formation in predisposed patients. Both the collagen fibers and chondrocyte-like cells seem to be involved in the primary formation of CPPD deposits in the synovium as well as in the cartilage.In calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, crystals appear to deposit virtually only in articular and periarticular connective tissues, mainly fibrocartilage, hyaline cartilage, and synovium, and, less often, in tendons, ligaments, and bursae (1-3). The proposed mechanisms involved in CPPD deposition in cartilage include increased production or impaired removal of calcium and inorganic pyrophosphate (PPJ (1,2,4-6), decreased magnesium concentrations (7,8), and various cellular and matrix factors, which can promote, nucleate, or inhibit crystal deposition (1,2,9).Local tissue factors probably play an important role in CPPD deposition disease and possibly determine the preferential articular localization of crystal deposits. McCarty et a1 described CPPD deposits