変形性関節症を理解する

The Clinical Basis of Osteoarthritis

はじめに

　変形性関節症（osteoarthritis：OA）は，中高年者の多くが罹患するcommon diseaseであり，特に高齢者では要介護や要支援の主要な原因となることから社会的問題となっている．OAでは関節に対する力学的あるいは生物的な原因によって関節軟骨が変性し，引き続き関節周囲の骨変化および滑膜炎が生じる．OAは関節軟骨の存在する全身の関節に発生する．股，膝，足，肩，肘などの大関節はもちろん，脊椎の椎間関節や指趾の関節でも関節症性変化が多くみられる（図1）．OAに対する治療としてさまざまな保存療法と手術療法がある．これらの中でも運動療法や装具療法は安全で効果的な保存療法である．また，手術療法の周術期においてもリハビリテーション（以下，リハ）の介入は必須であることから，リハ科医にとってOAに対する理解を深めることは重要である．本稿ではOAの疫学，病態，診断，治療について概説する．

Abstract : 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.