Diagnosis and clinical presentation of osteoarthritis.

Osteoarthritis (OA), the commonest arthropathy, targets the knees, hips, finger interphalangeal joints, thumb bases, first metatarsophalangeal joints, and spinal facet joints, and displays marked heterogeneity of clinical presentation. Signs of OA include coarse crepitus, bony enlargement, reduced range of movement, and joint-line tenderness. Muscle wasting and joint deformity occur with severe OA. Painful periarticular disorders often coexist with OA. Inflammation is absent or only modest, although mild-moderate effusions are common at the knee. The diagnosis of OA may be made without recourse to radiographic or laboratory investigations in the at-risk age group with typical symptoms and signs.