Cross-Sectional Study of 50 Patients with Calcium Pyrophosphate Dihydrate Crystal Arthropathy

Abstract

Calcium pyrophosphate dihydrate crystal arthropathy (CPPA) is a well known but heterogeneous disease with a variable presentation and course. We present a cross-sectional study undertaken in a Portuguese rheumatology unit with the aim of analysing clinical and radiological patterns of CPPA in our population. The study population included 50 patients, 34 (68%) women and 16 (32%) men. The mean age was 69.8 +/- 8.8 years. The onset features were acute arthritis in 19 (38%) patients and chronic joint complaints in 26 (52%); five (10%) patients were asymptomatic at the time of diagnosis, which was based only on radiological findings. The diagnosis was established in 37 (74%) cases by clinical and radiographic features, in eight (16%) by clinical, X-ray and synovial fluid analysis, and in five (10%) by clinical features and fluid analysis. The disease course was characterised by acute episodic arthritis in 16 (32%) patients and by persistent symptoms (with or without synovitis) in 34 (68%). The pattern of CPPA in 20 (40%) patients was pseudo-osteoarthritis with synovitis, pseudo-osteoarthritis without synovitis in nine (18%), pseudogout in nine (18%), monoarthropathy in eight (16%) and pseudorheumatoid arthritis in four (8%). The phosphocalcium balance was altered in nine (18%) cases: six patients had hypercalciuria two hyperphosphaturia, two hypocalciuria, one hypophosphaturia and one hypercalcemia. Five patients had abnormal thyroid hormone levels, but only one presented with clinical hypothyroidism. Four patients showed increased parathormone levels, but only one presented with clinical hyperparathyroidism. Radiographic findings showed that 43 (86%) patients had meniscus calcifications, 20 (40%) radiocarpal and 16 (32%) calcification of the symphysis pubis. The study confirms the clinical variability of the disease in a population of Portuguese patients. The knee meniscus calcifications were the most sensitive single finding for establishing the diagnosis of CPPA. Almost all our patients had sporadic idiopathic CPPA without associated pathological conditions.

Analysis of meniscal degeneration and meniscal gene expression

“…In the present study, we found that many genes which are involved in biomineral formation such as ENPP1 [23], in phosphate metabolic process such as ITGB2 and in calcium ion transport such as calcium channel, voltage-dependent, L type, alpha 1C subunit ( CACNA1C ) are expressed at an elevated levels in OA meniscal cells compared to normal meniscal cells. These findings are consistent with clinical observations that meniscal calcification is more severe in OA menisci [24,25] and that calcium content in OA menisci is positively correlated with the stage of meniscal degeneration [26]. In addition to the genes listed in Table 3, several other genes that have been previously implicated in pathological calcification were also detected (Table 4).…”

European League Against Rheumatism recommendations for calcium pyrophosphate deposition. Part I: terminology and diagnosis

“…Hospital-based series suggest that OA with CPPD may differ from OA without CPPD in showing more osteophytosis,18–21 different joint involvement22–26 and more inflammatory features (table 3). However, whether OA with CPPD is a distinct OA ‘subset’ remains unclear.…”

“…Compared with isolated OA, OA with CPPD may occur in less typical locations (eg, radiocarpal joints, elbows) and show more patellofemoral compartment involvement 22 26 25. Triangular fibrocartilage CC and calcification of intrinsic carpal ligaments (particularly lunotriquetral) and capsules is also seen;24 calcification of the gastrocnemius tendon origin may also associate with CPPD in knees 25.…”

Comparison of Meniscal Cell-Mediated and Chondrocyte-Mediated Calcification

“…Studies found that 86% of patients with CPPD disease displayed calcified mineral deposits in the meniscus and that calcification increased with age [22, 23]. In a previous study conducted in our laboratory, we showed that OA meniscal cells produced more calcium deposits in culture than normal meniscal cells and displayed elevated expression of several genes involved in biomineralization [24].…”