Osteoarthritis (OA) is one of the most prevalent diseases in our society, right behind cardiovascular diseases and is often the reason for disability in the elderly of the Western world. Any joint can be affected, but it most commonly affects the knee, hip, foot, spine, and wrist joints. The knee joint (articulatio genus) is the largest joint in the human body. It connects the lower end of the femur and the upper end of the tibia. Knee structures can be divided into several categories. Menisci (menisci articularis) or connective cartilage plates, triangular in cross section, they ensure the comformity of the articular surfaces of femur and tibia. There are medial and lateral menisci, and they correspond to the shape of the letter C or sickle. The knee is a joint rich with ligaments that strengthen the joint capsule, the most important being two collaterals and two cruciate ligaments. Ligaments, all together are the most important structures that control the stability of the knee. Active knee stabilizers are muscles. Flexion, extension, but also internal and external rotation occur in it. Lateral and cruciate ligaments are very important for the stability and mechanics of the knee joint. OA is a chronic, degenerative, progressive disease of the joints, the main cause of which is the deterioration of the articular cartilage. It is estimated that gonarthrosis occurs above 60 in as many as 90% of people, affecting women more often than men. Primary or idiopathic gonarthrosis includes more than 50% of knee arthrosis, or arthrosis where the occurrence cannot be explained with the known causative factors. Secondary OA is closely related to a known event or disease. Understanding the changes in the early stages of the disease is essential to make it easier to treat. The first sign of gonarthrosis is pain that occurs after rest, and then gradually disappears, also patients describe it as dull or numb. The diagnosis is made on the basis of X-rays and a clinical examination of the knee to determine the degree of damage to the articular cartilage. Treatment of osteoarthritis includes surgical and non-surgical methods of treatment. Nurses must provide best quality health care, and the decisions nurses make must be based on the priorities of a patient. General preoperative preparation can be mental and physical. Education of patients in the preoperative period is important because it reduces the possibility of complications in the postoperative period. In the intraoperative period roles of the nurse are: prepares the patient for surgery, preparation of apparatus and instruments for anesthesia. In the postoperative period, the patient should be explained and told about the importance of conducting breathing and coughing exercises. Osteoarthritis is a disease that attacks the elderly and therefore the recovery phase lasts longer.