The detection of calcium pyrophosphate crystals in sequential synovial fluid examinations of patients with osteoarthritis: once positive, always positive

Abstract

The aim of this study was to investigate whether calcium pyrophosphate dihydrate (CPPD) crystals are constantly detectable in sequential synovial fluid (SF) examinations of patients with initially CPPD-positive osteoarthritis (OA). For this purpose, we searched our SF database for CPPD-positive patients, who had two or more SF analyses between 2008 and 2012 to get sequential information. The database contains SF data determined by a standardised procedure. Of 1,878 samples, examined within the defined time period, 60 samples from sequential SF analyses of 23 patients were eligible for this study. The number of examinations ranged from 2 to 7 (median, 2), and the median interval between the first and last arthrocentesis was 12 months (2-43). CPPD crystals were detected in all of the sequentially examined samples according to the defined criterion of positivity. All of the subjects had OA of the knee, with a median Kellgren-Lawrence grade of 3 in the initially performed X-rays, and meniscal calcifications were found in six subjects. In conclusion, our results suggest that CPPD crystals are a regular feature of sequentially examined SF of initially CPPD-positive patients with symptomatic OA of the knee.

The added value of synovial fluid centrifugation for monosodium urate and calcium pyrophosphate crystal detection

“…Based on the limited available evidence, EDTA preservation for several days seems comparable with instantaneous performed polarized light microscopy [14,16,17]. Thirdly, we used a conventional laboratory centrifuge, in contrast to other studies which used cytocentrifuges [6,7,9,10,[23][24][25][26]. Besides some disadvantages, mentioned before, the latter has important advantages: sedimentable particles from liquid suspensions can be directly transferred as a concentrated thin layer of cells onto a microscope slide without additional manual pipetting and it places cells and crystals in the same optical plane [6,7,9].…”

“…We already have shown that all samples that were MSU and CPP positive before centrifugation were also positive after. The centrifugation settings we used were chosen to increase comparability to other studies [6,7,9,10,[24][25][26].…”

Functional Annotation of Rheumatoid Arthritis and Osteoarthritis Associated Genes by Integrative Genome-Wide Gene Expression Profiling Analysis

“…Adequate calcium intake is the basis of osteoblast growth. Observation of the dysregulated expression of calcium related gene may partially explain why calcium pyrophosphate dihydrates accumulate in synovial of OA patients [42], [43]. Endocytosis and autophagy are the major pathways for materials to be transported into the lysosomes in cells.…”