Spectroscopic imaging techniques for detecting calcification in knee joint tissue

Abstract

Osteoarthritis (OA) is the most common form of arthritis that is costly both economically and socially(1). Since OA is irreversible, researchers are constantly seeking the most efficient and reliable method of diagnosing it at an early stage. OA is closely associated with the development of calcifications in soft tissues of the knee joint, such as the meniscus and articular cartilage (AC). These crystal-induced calcifications may represent a potential target for disease-modifying agents in OA treatment. The presence of OA-associated crystals can be also found in the synovial fluid (SF). Among the most common types of crystals found to be associated with OA are basic calcium phosphate (BCP) and calcium phosphate dihydrate (CPPD)(2). Although BCP and CPPD crystals may coexist, their clinical patterns and etiology differ significantly(3). The detection and characterization of OA-related crystals are challenging since they have sub-micron structures, and they can coexist with other crystal deposition disorders like pseudogout or gout. OA-related changes in AC and SF have been extensively studied, in addition, in recent years the meniscus has also been taken into consideration. It has been reported that the meniscus can be calcified even though the AC is not(2). According to these results, meniscal calcification may potentially be a risk factor for cartilage lesions. There are a number of analytical techniques that have been applied to detect and characterize crystals in knee joint tissue, either directly or indirectly. This thesis focuses on different spectroscopic techniques available for detecting calcium crystals in synovial fluid, articular cartilage, and meniscus of the knee joint. Particularly, this thesis aims to systematically review the spectroscopic studies related to the detection of calcification from knee join tissue and presents an experiment that characterizes calcifications in meniscus using Raman spectroscopy.