Osteoarthritis (OA) is a complex disease process with cartilage thinning and fibrillation, subchondral sclerosis, and osteophyte (bone spur) development. This prevalent joint condition causes stiffness of the joints, significant pain, limited or impaired function, and decreased mobility (Petersson & Jacobsson, 2002). OA is a chronic disease affecting over 50% of people over the age of 65 years, and around 10% of men and 18% of women have symptomatic OA.
How is Osteoarthritis Diagnosed?
There is progressive destruction of the articular cartilage in OA patients. Physicians use several methods to diagnose people with this disabling joint disease, and the diagnosis is primarily made according to radiographic findings as well as the presence of certain clinical signs and symptoms. Radiologic evaluation of joint images provides a historical view of the damage that has occurred with OA. There are other alternative methods for diagnosis, such as molecular markers and synovial fluid analysis. These diagnostic techniques can be used not just for diagnosis, but also for prognosis and disease progression monitoring. These various diagnostic methods are important for the development of new disease-modifying treatments (DeGroot, Bank, Tchetverikov, Verzijl, & TeKoppele, 2002).
Synovial Fluid Evaluation
- Viscosity – This has been a primary method of diagnosis used by researchers in the field of rheumatology for many years. Viscosity synovial fluid evaluation is done by assessing the physiochemical properties of the synovial fluid in subjects with OA and comparing it to the synovial fluid of subjects without the disease (Esmonde-White, 2009).
- Inorganic Crystals – Because microscopic inorganic crystals are frequently observed in the synovial fluid of people with OA, basic calcium phosphate (BCP) crystals are diagnostic for the condition. BCP crystals are insoluble at physiological pH. Currently, evaluation of OA patients’ synovial fluid is dependent on light microscopy and staining with Alizarin Red-S. Researchers also used O-cresolphtahalein complexone (OCP), a colorimetric reagent, to quantify calcium from the crystals in synovial fluid and found it to be indicative of BCP presence in the fluid. The scientists found that the average calcium content in those with OA was up to 40% higher than in patients with rheumatoid arthritis. Higher levels of calcium were also detected in 3 out of 12 synovial fluid samples in the OA group, correlating a substantial greater number of BCP crystals. This basic method is based on colorimetry and improves OA diagnosis.
- Raman Spectroscopy – In one recent study, researchers evaluated the synovial fluid of 40 people with clinical OA of the knee, and the severity of the OA was also evaluated by a radiology using Kellgren/Lawrence scores. Ramen spectroscopy was then used to assess the synovial fluid, and the scientists found that Raman bands corresponded to changes in synovial fluid structure in OA patients. This research provided evidence that Raman spectroscopy is suitable for determining the extent of joint damage in patients with knee OA (Esmonde-White et al., 2009).
According to researcher DeGroot and associates (2002), molecular markers are necessary for diagnosis, they reflect actual disease activity, are sensitive to therapy, and predict the disease outcome. Different molecular markers can be used for preclinical studies of OA pathophysiology and for creation of new treatments. Certain genetic markers have been shown to offer essential information on risk factors for the development and progression of OA.