Osteoarthritis is a complicated and mixed condition that affects the whole joints including the bones , cartilage and soft tissues. The incidence of Osteoarthritis increases with advancing age , obesity and joint injuries being the major causes. The most outstanding sign of Osteoarthritis is chronic pain that does not let people function effectively daily. Though the pathogenesis of OA has not been fully elucidated, it is often considered to be an imbalance between catabolic and anabolic processes in articular cartilage. The risk factors that could lead to OA are ageing, genetic predisposition, body mass index, sex race, trauma and co-morbidities such as diabetes and cardiovascular diseases. Diagnosis of OA is confirmed using imaging modalities like MRI, ultrasound and X-rays. This review will focus on the pathogenesis, risk factors and various diagnostic approaches.