The synovium is a thin layer of tissue only a few cells thick which lines the joints and tendon sheaths. It controls the environment within the joint and tendon sheath by acting as a membrane to determine what can pass into the joint space and what stays outside. The synovium may become thickened and inflamed, causing pain within the affected joint. This book covers a range of disorders associated with the synovium, discussing both rare and more common conditions. Beginning with an introduction and description of normal synovium, the following chapters examine the pathology and arthroscopic findings of different types of arthritis, tumours and tumour-like lesions and synovial fluid. The final chapter discusses the histology of arthritis, amyloid (protein) related disorders and haemophilia.