Metabolic arthropathies.

In this article, recent advances in the understanding of some of the metabolic arthropathies are reviewed. Among hemoglobinopathies, sickle-cell disease is frequently the source of rheumatic syndromes, as emphasized in recent epidemiologic studies. Avascular necrosis is one of the most common features and may be disabling, leading to total joint replacement of the hip or knee. Joint effusions more rarely are observed and have been associated with subchondral bone infarctions. The clinical and radiologic presentations of the arthropathy of hemochromatosis have been extensively reviewed. Screening for the disease appears important, because it is the only way to prevent progressive worsening of organ involvement and arthropathy in particular. The rheumatic involvement in type IIa and type III hyperlipoproteinemias recently was confirmed in a case-control study. Magnetic resonance imaging appears to be useful in assessing the extent and activity of bone marrow involvement in Gaucher's disease. Replacement therapy is developing. Dialysis-associated amyloidosis remains the target of active research, which recently led to the identification of several newly recognized components, including alpha 2-macroglobulin and hyaluronan. The main component of this amyloid, beta 2-microglobulin, has been shown to be modified by advanced glycosylation products, and these changes appear to confer inflammatory properties on the molecule.

[Rheumatological complications of dialysis]. / Les complications rhumatologiques des dialysés.

The articular complications observed in dialysed chronic renal failure failures, whose incidence increases with the duration of dialysis, are closely correlated with the development of beta 2-microglobulin amyloidosis, responsible for nerve tunnel syndromes, arthralgia and chronic joint swelling with frequently multiple subchondral cysts on x-rays. Microcrystalline pathology is dominated by apatite deposits, which may also be involved in the pathogenesis of destructive arthropathy. Articular complications with destruction of the large joints or involvement of the first carpometacarpal joint interfere with the functional prognosis. Sepsis must be excluded in cases of destructive cervical spondyloarthropathies. The pathogenesis of destructive arthropathies is probably multifactorial, consisting of apatite and amyloid deposits, secondary hyperparathyroidism and aluminium poisoning.

Decrease of tumor-like calcification in uremia despite aggravation of secondary hyperparathyroidism: a case report.

Extraskeletal pseudotumoral calcifications generally develop in uremic patients with a high calcium x phosphorus (Ca x P) product and severe secondary hyperparathyroidism. In the present case report we describe a chronic hemodialysis patient presenting with a massive calcification of the left shoulder region, severe aluminum (Al) intoxication and moderate hyperparathyroidism. Her initial serum Ca x P product was only slightly elevated: 5.01 mmol2/l2. Under deferoxamine treatment during the subsequent 4 months, Al overload decreased. On the other hand, parathyroid overfunction worsened, as reflected by an increase of the serum immunoreactive parathyroid hormone [1-84] level from initially 690 to 1052 pg/ml (normal, 15-60 pg/ml) and an increase of alkaline phosphatase activity, and plasma calcitriol increased from undetectable to a low-normal value. Predialysis serum total Ca levels decreased rapidly from 2.9 to 2.5 mM but serum P concentrations remained elevated: 1.6-2.5 mM. Unexpectedly, the extent of the periarticular calcification diminished considerably during the same time period. The present observation shows that in a subset of uremic patients with Al overload, pseudotumoral calcifications may regress during Al chelation therapy despite progression of hyperparathyroidism. Since Al may predispose collagen to develop dystrophic or metastatic calcification, it is suggested that this process is reversible by correcting Al intoxication.

[Articular inflammation of microcrystalline origin]. / Inflammations articulaires d'origine microcristalline.

Microcrystals of sodium urate, calcium pyrophosphate, hydroxyapatite and corticosteroids may induce acute arthritis by similar mechanisms in which neutrophils play the most important role. Interactions between neutrophils and microcrystals result in the release of several phlogogenic substances, e.g. lysosomal enzymes, chemotactic factor (CCF) or leukotrienes. Various proteins may be adsorbed to the surface of microcrystals, and this protein coating seems to be instrumental in modulating the neutrophil-microcrystal interaction. The Hageman factor and the complement system may also be activated. The mechanisms starting off and resolving articular attacks are discussed.