Detection of basic calcium phosphate crystals in osteoarthritis

Osteoarthritis (OA) is the most common human joint disorder. Its complex pathogenesis remains poorly understood but appears multifactorial. To date, no specific pharmacological agent has been identified to alter the disease course of OA. Calcification of articular cartilage is a hallmark of OA and evidence suggests it contributes directly to joint degeneration. Calcium crystals are frequently found in OA synovial fluid but their exact role in the disease process is unclear. Basic calcium phosphate (BCP) crystals are the predominant crystal type found in OA and recent data indicate a pathogenic role for these crystals in OA. However, information on the exact frequency and distribution of BCP crystals vary considerably, mainly due to the lack of simple and reliable methods of detection. The purpose of this review is to describe the current available methods for detecting BCP crystals and to highlight their obvious advantages and limitations. Recent developments in the field are also discussed with particular reference to their potential clinical applicability. Improved methods of detection for BCP crystals could potentially aid the diagnosis of OA and the development of novel therapies.