Osteoarthritis (OA) is a non-inflammatory joint disease that is characterized by cartilage degeneration. OA can develop in any joint with synovium and articular cartilage. OA is a very common disease in old age which can cause patients to become housebound or to require nursing care. Epidemiological research in Japan showed that the estimated number of patients with radiographic knee OA was 25 million and those with radiographic lumbar OA was 38 million. OA induces pain, contracture, hydrarthrosis and joint deformity. These in turn lead to gait disturbance in the lower limb and disorders of ADL in the upper limb. On plain radiography, joint space narrowing, osteophyte formation and bone cysts are observed. Several treatment guidelines for OA were published by several academies associated with OA. Various conservative treatments and surgical treatments are often applied to OA. Patient education, exercise and orthoses are effective in improving pain and functional impairment. As a drug therapy, acetaminophen, NSAIDs and opioids are used to reduce pain in OA. Additionally, steroid and hyaluronic intra-articular injection are widely used in the treatment of OA. If the conservative therapies are not effective, surgical therapies are considered. Surgical therapies are categorized into osteotomy, arthroplasty, arthrodesis and replacement arthroplasty. Recently, total knee and hip arthroplasties are becoming very common. Since exercise and orthosis therapy are effective for OA, rehabilitation doctors should have an understanding of the pathology and treatment of OA. In addition, rehabilitation is very important before and after surgery.
